DOC: Move from texinfo to sphinx

author: Martin Schanzenbach <schanzen@gnunet.org> 2022-08-02 17:25:41 +0200
committer: Martin Schanzenbach <schanzen@gnunet.org> 2022-08-02 17:25:41 +0200
commit: 4fe567d9d94b9159254a2f2cce64855a794d9699 (patch)
tree: b286f5a454472ec92ff88376b297e411e64c5843 /doc/handbook/chapters
parent: e8b7707f833739851227d4865e6c6064865f19ec (diff)
download: gnunet-4fe567d9d94b9159254a2f2cce64855a794d9699.tar.gz
gnunet-4fe567d9d94b9159254a2f2cce64855a794d9699.zip
9 files changed, 0 insertions, 16164 deletions
diff --git a/doc/handbook/chapters/configuration.texi b/doc/handbook/chapters/configuration.texi
deleted file mode 100644
index 27efc82e2..000000000
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-@node Configuration Handbook
-@chapter Configuration Handbook
-This chapter has yet to be fully written.  It is intended to be about in-depth
-configuration of GNUnet.
-@menu
-* Config file format::
-@end menu
-@node Config file format
-@section Config file format
-In GNUnet realm, all components obey the same pattern to get configuration
-values.  According to this pattern, once the component has been installed, the
-installation deploys default values in @file{$prefix/share/gnunet/config.d/},
-in @file{.conf} files.  In order to override these defaults, the user can
-write a custom @file{.conf} file and either pass it to the component at
-execution time, or name it @file{gnunet.conf} and place it under
-@file{$HOME/.config/}.
-A config file is a text file containing sections, and each section
-contains its values.  The right format follows:
-@example
-[section1]
-value1 = string
-value2 = 23
-[section2]
-value21 = string
-value22 = /path22
-@end example
-Throughout any configuration file, it is possible to use @code{$}-prefixed
-variables, like @code{$VAR}, especially when they represent filenames in in
-the filesystem.  It is also possible to provide defaults values for those
-variables that are unset, by using the following syntax:
-@example
-$@{VAR:-default@}
-@end example
-@noindent
-However, there are two ways a user can set @code{$}-prefixable variables:
-(a) by defining them under a @code{[paths]} section
-@example
-[paths]
-GNUNET_DEPLOYMENT_SHARED = $@{HOME@}/shared-data
-..
-[section-x]
-path-x = $@{GNUNET_DEPLOYMENT_SHARED@}/x
-@end example
-@noindent
-or (b) by setting them in the environment
-@example
-$ export VAR=/x
-@end example
-@noindent
-The configuration loader will give precedence to variables set under
-@code{[path]}, though.
-The utility @samp{gnunet-config}, which gets installed along with GNUnet,
-serves to get and set configuration values without directly editing the
-@file{.conf} file.  The option @samp{-f} is particularly useful to resolve
-filenames, when they use several levels of @code{$}-expanded variables.
-See @samp{gnunet-config --help}.
-Note that, in this stage of development, the file
-@file{$HOME/.config/gnunet.conf} can contain sections for @strong{all} the
-components.
diff --git a/doc/handbook/chapters/contributing.texi b/doc/handbook/chapters/contributing.texi
deleted file mode 100644
index f3beeef76..000000000
--- a/doc/handbook/chapters/contributing.texi
+++ /dev/null
@@ -1,117 +0,0 @@
-@node GNUnet Contributors Handbook
-@chapter GNUnet Contributors Handbook
-@menu
-* Contributing to GNUnet::
-* Licenses of contributions::
-* Copyright Assignment::
-* Contributing to the Reference Manual::
-* Contributing testcases::
-@end menu
-@node Contributing to GNUnet
-@section Contributing to GNUnet
-@cindex licenses
-@cindex licenses of contributions
-@node Licenses of contributions
-@section Licenses of contributions
-GNUnet is a @uref{https://www.gnu.org/, GNU} package.
-All code contributions must thus be put under the
-@uref{https://www.gnu.org/licenses/agpl.html, GNU Affero Public License (AGPL)}.
-All documentation should be put under FSF approved licenses
-(see @uref{https://www.gnu.org/copyleft/fdl.html, fdl}).
-By submitting documentation, translations, and other content to GNUnet
-you automatically grant the right to publish code under the
-GNU Public License and documentation under either or both the
-GNU Public License or the GNU Free Documentation License.
-When contributing to the GNUnet project, GNU standards and the
-@uref{https://www.gnu.org/philosophy/philosophy.html, GNU philosophy}
-should be adhered to.
-@cindex copyright assignment
-@node Copyright Assignment
-@section Copyright Assignment
-We require a formal copyright assignment for GNUnet contributors
-to GNUnet e.V.; nevertheless, we do allow pseudonymous contributions.
-By signing the copyright agreement and submitting your code (or
-documentation) to us, you agree to share the rights to your code
-with GNUnet e.V.; GNUnet e.V. receives non-exclusive ownership
-rights, and in particular is allowed to dual-license the code. You
-retain non-exclusive rights to your contributions, so you can also
-share your contributions freely with other projects.
-GNUnet e.V. will publish all accepted contributions under the AGPLv3
-or any later version. The association may decide to publish
-contributions under additional licenses (dual-licensing).
-We do not intentionally remove your name from your contributions;
-however, due to extensive editing it is not always trivial to
-attribute contributors properly. If you find that you significantly
-contributed to a file (or the project as a whole) and are not listed
-in the respective authors file or section, please do let us know.
-@node Contributing to the Reference Manual
-@section Contributing to the Reference Manual
-@itemize @bullet
-@item When writing documentation, please use
-@uref{https://en.wikipedia.org/wiki/Singular_they, gender-neutral wording}
-when referring to people, such as singular “they”, “their”, “them”, and so
-forth.
-@item Keep line length below 74 characters, except for URLs.
-URLs break in the PDF output when they contain linebreaks.
-@item Do not use tab characters (see chapter 2.1 texinfo manual)
-@item Write texts in the third person perspective.
-@c FIXME: This is questionable, it feels like bike shed painging to do
-@c this for several k lines. It only helps to jump between sentences in
-@c editors afaik.
-@c @item Use 2 spaces between sentences, so instead of:
-@c @example
-@c We do this and the other thing. This is done by foo.
-@c @end example
-@c Write:
-@c @example
-@c We do this and the other thing.  This is done by foo.
-@c @end example
-@end itemize
-@node Contributing testcases
-@section Contributing testcases
-In the core of gnunet, we restrict new testcases to a small subset
-of languages, in order of preference:
-@enumerate
-@item C
-@item Portable Shell Scripts
-@item Python (3.7 or later)
-@end enumerate
-We welcome efforts to remove our existing python-2.7 scripts to
-replace them either with portable shell scripts or,
-at your choice, python-3.7+.
-If you contribute new python based testcases, we advise you to
-not repeat our past misfortunes and write the tests in a standard
-test framework like for example pytest.
-For writing portable shell scripts, these tools are useful:
-@uref{https://github.com/koalaman/shellcheck, Shellcheck},
-@uref{https://salsa.debian.org/debian/devscripts/blob/master/scripts/checkbashisms.pl, checkbashisms},
-@uref{http://www.etalabs.net/sh_tricks.html},
-@uref{https://wiki.ubuntu.com/DashAsBinSh},
-and @uref{https://mywiki.wooledge.org/Bashism}
-@c You could also run "bin/check_shell_script" (which we still have
-@c to write).
diff --git a/doc/handbook/chapters/developer.texi b/doc/handbook/chapters/developer.texi
deleted file mode 100644
index c8905f2c1..000000000
--- a/doc/handbook/chapters/developer.texi
+++ /dev/null
@@ -1,10154 +0,0 @@
-@c ***********************************************************************
-@node GNUnet Developer Handbook
-@chapter GNUnet Developer Handbook
-This book is intended to be an introduction for programmers that want to
-extend the GNUnet framework. GNUnet is more than a simple peer-to-peer
-application.
-For developers, GNUnet is:
-@itemize @bullet
-@item developed by a community that believes in the GNU philosophy
-@item Free Software (Free as in Freedom), licensed under the
-GNU Affero General Public License
-(@uref{https://www.gnu.org/licenses/licenses.html#AGPL})
-@item A set of standards, including coding conventions and
-architectural rules
-@item A set of layered protocols, both specifying the communication
-between peers as well as the communication between components
-of a single peer
-@item A set of libraries with well-defined APIs suitable for
-writing extensions
-@end itemize
-In particular, the architecture specifies that a peer consists of many
-processes communicating via protocols. Processes can be written in almost
-any language.
-@code{C}, @code{Java} and @code{Guile} APIs exist for accessing existing
-services and for writing extensions.
-It is possible to write extensions in other languages by
-implementing the necessary IPC protocols.
-GNUnet can be extended and improved along many possible dimensions, and
-anyone interested in Free Software and Freedom-enhancing Networking is
-welcome to join the effort. This Developer Handbook attempts to provide
-an initial introduction to some of the key design choices and central
-components of the system.
-This part of the GNUnet documentation is far from complete,
-and we welcome informed contributions, be it in the form of
-new chapters, sections or insightful comments.
-@menu
-* Developer Introduction::
-* Internal dependencies::
-* Code overview::
-* System Architecture::
-* Subsystem stability::
-* Naming conventions and coding style guide::
-* Build-system::
-* Developing extensions for GNUnet using the gnunet-ext template::
-* Writing testcases::
-* Building GNUnet and its dependencies::
-* TESTING library::
-* Performance regression analysis with Gauger::
-* TESTBED Subsystem::
-* libgnunetutil::
-* Automatic Restart Manager (ARM)::
-* TRANSPORT Subsystem::
-* NAT library::
-* Distance-Vector plugin::
-* SMTP plugin::
-* Bluetooth plugin::
-* WLAN plugin::
-* ATS Subsystem::
-* CORE Subsystem::
-* CADET Subsystem::
-* NSE Subsystem::
-* HOSTLIST Subsystem::
-* IDENTITY Subsystem::
-* NAMESTORE Subsystem::
-* PEERINFO Subsystem::
-* PEERSTORE Subsystem::
-* SET Subsystem::
-* SETI Subsystem::
-* SETU Subsystem::
-* STATISTICS Subsystem::
-* Distributed Hash Table (DHT)::
-* GNU Name System (GNS)::
-* GNS Namecache::
-* REVOCATION Subsystem::
-* File-sharing (FS) Subsystem::
-* REGEX Subsystem::
-* REST Subsystem::
-* RPS Subsystem::
-* TRANSPORT-NG Subsystem::
-* MESSENGER Subsystem::
-@end menu
-@node Developer Introduction
-@section Developer Introduction
-This Developer Handbook is intended as first introduction to GNUnet for
-new developers that want to extend the GNUnet framework. After the
-introduction, each of the GNUnet subsystems (directories in the
-@file{src/} tree) is (supposed to be) covered in its own chapter. In
-addition to this documentation, GNUnet developers should be aware of the
-services available on the GNUnet server to them.
-New developers can have a look a the @uref{https://docs.gnunet.org/tutorial/tutorial.html, GNUnet C tutorial}.
-@c ** FIXME: Link to files in source, not online.
-@c ** FIXME: Where is the Java tutorial?
-In addition to the GNUnet Reference Documentation you are reading,
-the GNUnet server at @uref{https://gnunet.org} contains
-various resources for GNUnet developers and those
-who aspire to become regular contributors.
-They are all conveniently reachable via the "Developer"
-entry in the navigation menu. Some additional tools (such as continuous
-integration) require a special developer access to perform certain
-operations. If you want (or require) access, you should contact
-GNUnet's maintainers.
-@c FIXME: A good part of this belongs on the website or should be
-@c extended in subsections explaining usage of this. A simple list
-@c is just taking space people have to read.
-The developer services on the GNUnet project infrastructure are:
-@itemize @bullet
-@item The version control system (git) keeps our code and enables
-distributed development.
-It is publicly accessible at @uref{https://git.gnunet.org/}.
-Only developers with write access can commit code, everyone else is
-encouraged to submit patches to the GNUnet-developers mailinglist:
-@uref{https://lists.gnu.org/mailman/listinfo/gnunet-developers, https://lists.gnu.org/mailman/listinfo/gnunet-developers}
-@item The bugtracking system (Mantis).
-We use it to track feature requests, open bug reports and their
-resolutions.
-It can be accessed at
-@uref{https://bugs.gnunet.org/, https://bugs.gnunet.org/}.
-Anyone can report bugs.
-@item Continuous integration (Buildbot).
-Used to build gnunet and its websites upon new commits.
-It can be accessed at
-@uref{https://buildbot.gnunet.org/, https://buildbot.gnunet.org/}.
-Anyone can see the builds.
-@item Regularly we make use of static analysis tools.
-Note that not everything that is flagged by the
-analysis is a bug, sometimes even good code can be marked as possibly
-problematic. Nevertheless, developers are encouraged to at least be
-aware of all issues in their code that are listed.
-@c @item We use Gauger for automatic performance regression visualization.
-@c FIXME: LINK!
-@c Details on how to use Gauger are here.
-@end itemize
-@c ***********************************************************************
-@menu
-* Project overview::
-@end menu
-@node Project overview
-@subsection Project overview
-The GNUnet project consists at this point of several sub-projects. This
-section is supposed to give an initial overview about the various
-sub-projects. Note that this description also lists projects that are far
-from complete, including even those that have literally not a single line
-of code in them yet.
-GNUnet sub-projects in order of likely relevance are currently:
-@table @asis
-@item @command{gnunet}
-Core of the P2P framework, including file-sharing, VPN and
-chat applications; this is what the Developer Handbook covers mostly
-@item @command{gnunet-gtk}
-Gtk+-based user interfaces, including:
-@itemize @bullet
-@item @command{gnunet-fs-gtk} (file-sharing),
-@item @command{gnunet-statistics-gtk} (statistics over time),
-@item @command{gnunet-peerinfo-gtk}
-(information about current connections and known peers),
-@item @command{gnunet-namestore-gtk} (GNS record editor),
-@item @command{gnunet-conversation-gtk} (voice chat GUI) and
-@item @command{gnunet-setup} (setup tool for "everything")
-@end itemize
-@item @command{gnunet-fuse}
-Mounting directories shared via GNUnet's file-sharing
-on GNU/Linux distributions
-@item @command{gnunet-update}
-Installation and update tool
-@item @command{gnunet-ext}
-Template for starting 'external' GNUnet projects
-@item @command{gnunet-java}
-Java APIs for writing GNUnet services and applications
-@item @command{gnunet-java-ext}
-@item @command{eclectic}
-Code to run GNUnet nodes on testbeds for research, development,
-testing and evaluation
-@c ** FIXME: Solve the status and location of gnunet-qt
-@item @command{gnunet-qt}
-Qt-based GNUnet GUI (is it deprecated?)
-@item @command{gnunet-cocoa}
-cocoa-based GNUnet GUI (is it deprecated?)
-@item @command{gnunet-guile}
-Guile bindings for GNUnet
-@item @command{gnunet-python}
-Python bindings for GNUnet
-@end table
-We are also working on various supporting libraries and tools:
-@c ** FIXME: What about gauger, and what about libmwmodem?
-@table @asis
-@item @command{libextractor}
-GNU libextractor (meta data extraction)
-@item @command{libmicrohttpd}
-GNU libmicrohttpd (embedded HTTP(S) server library)
-@item @command{gauger}
-Tool for performance regression analysis
-@item @command{monkey}
-Tool for automated debugging of distributed systems
-@item @command{libmwmodem}
-Library for accessing satellite connection quality reports
-@item @command{libgnurl}
-gnURL (feature-restricted variant of cURL/libcurl)
-@item @command{www}
-the gnunet.org website (Jinja2 based)
-@item @command{bibliography}
-Our collected bibliography, papers, references, and so forth
-@item @command{gnunet-videos-}
-Videos about and around GNUnet activities
-@end table
-Finally, there are various external projects (see links for a list of
-those that have a public website) which build on top of the GNUnet
-framework.
-@c ***********************************************************************
-@node Internal dependencies
-@section Internal dependencies
-This section tries to give an overview of what processes a typical GNUnet
-peer running a particular application would consist of. All of the
-processes listed here should be automatically started by
-@command{gnunet-arm -s}.
-The list is given as a rough first guide to users for failure diagnostics.
-Ideally, end-users should never have to worry about these internal
-dependencies.
-In terms of internal dependencies, a minimum file-sharing system consists
-of the following GNUnet processes (in order of dependency):
-@itemize @bullet
-@item gnunet-service-arm
-@item gnunet-service-resolver (required by all)
-@item gnunet-service-statistics (required by all)
-@item gnunet-service-peerinfo
-@item gnunet-service-transport (requires peerinfo)
-@item gnunet-service-core (requires transport)
-@item gnunet-daemon-hostlist (requires core)
-@item gnunet-daemon-topology (requires hostlist, peerinfo)
-@item gnunet-service-datastore
-@item gnunet-service-dht (requires core)
-@item gnunet-service-identity
-@item gnunet-service-fs (requires identity, mesh, dht, datastore, core)
-@end itemize
-@noindent
-A minimum VPN system consists of the following GNUnet processes (in
-order of dependency):
-@itemize @bullet
-@item gnunet-service-arm
-@item gnunet-service-resolver (required by all)
-@item gnunet-service-statistics (required by all)
-@item gnunet-service-peerinfo
-@item gnunet-service-transport (requires peerinfo)
-@item gnunet-service-core (requires transport)
-@item gnunet-daemon-hostlist (requires core)
-@item gnunet-service-dht (requires core)
-@item gnunet-service-mesh (requires dht, core)
-@item gnunet-service-dns (requires dht)
-@item gnunet-service-regex (requires dht)
-@item gnunet-service-vpn (requires regex, dns, mesh, dht)
-@end itemize
-@noindent
-A minimum GNS system consists of the following GNUnet processes (in
-order of dependency):
-@itemize @bullet
-@item gnunet-service-arm
-@item gnunet-service-resolver (required by all)
-@item gnunet-service-statistics (required by all)
-@item gnunet-service-peerinfo
-@item gnunet-service-transport (requires peerinfo)
-@item gnunet-service-core (requires transport)
-@item gnunet-daemon-hostlist (requires core)
-@item gnunet-service-dht (requires core)
-@item gnunet-service-mesh (requires dht, core)
-@item gnunet-service-dns (requires dht)
-@item gnunet-service-regex (requires dht)
-@item gnunet-service-vpn (requires regex, dns, mesh, dht)
-@item gnunet-service-identity
-@item gnunet-service-namestore (requires identity)
-@item gnunet-service-gns (requires vpn, dns, dht, namestore, identity)
-@end itemize
-@c ***********************************************************************
-@node Code overview
-@section Code overview
-This section gives a brief overview of the GNUnet source code.
-Specifically, we sketch the function of each of the subdirectories in
-the @file{gnunet/src/} directory. The order given is roughly bottom-up
-(in terms of the layers of the system).
-@table @asis
-@item @file{util/} --- libgnunetutil
-Library with general utility functions, all
-GNUnet binaries link against this library. Anything from memory
-allocation and data structures to cryptography and inter-process
-communication. The goal is to provide an OS-independent interface and
-more 'secure' or convenient implementations of commonly used primitives.
-The API is spread over more than a dozen headers, developers should study
-those closely to avoid duplicating existing functions.
-@pxref{libgnunetutil}.
-@item @file{hello/} --- libgnunethello
-HELLO messages are used to
-describe under which addresses a peer can be reached (for example,
-protocol, IP, port). This library manages parsing and generating of HELLO
-messages.
-@item @file{block/} --- libgnunetblock
-The DHT and other components of GNUnet
-store information in units called 'blocks'. Each block has a type and the
-type defines a particular format and how that binary format is to be
-linked to a hash code (the key for the DHT and for databases). The block
-library is a wrapper around block plugins which provide the necessary
-functions for each block type.
-@item @file{statistics/} --- statistics service
-The statistics service enables associating
-values (of type uint64_t) with a component name and a string. The main
-uses is debugging (counting events), performance tracking and user
-entertainment (what did my peer do today?).
-@item @file{arm/} --- Automatic Restart Manager (ARM)
-The automatic-restart-manager (ARM) service
-is the GNUnet master service. Its role is to start gnunet-services, to
-re-start them when they crashed and finally to shut down the system when
-requested.
-@item @file{peerinfo/} --- peerinfo service
-The peerinfo service keeps track of which peers are known
-to the local peer and also tracks the validated addresses for each peer
-(in the form of a HELLO message) for each of those peers. The peer is not
-necessarily connected to all peers known to the peerinfo service.
-Peerinfo provides persistent storage for peer identities --- peers are
-not forgotten just because of a system restart.
-@item @file{datacache/} --- libgnunetdatacache
-The datacache library provides (temporary) block storage for the DHT.
-Existing plugins can store blocks in Sqlite, Postgres or MySQL databases.
-All data stored in the cache is lost when the peer is stopped or
-restarted (datacache uses temporary tables).
-@item @file{datastore/} --- datastore service
-The datastore service stores file-sharing blocks in
-databases for extended periods of time. In contrast to the datacache, data
-is not lost when peers restart. However, quota restrictions may still
-cause old, expired or low-priority data to be eventually discarded.
-Existing plugins can store blocks in Sqlite, Postgres or MySQL databases.
-@item @file{template/} --- service template
-Template for writing a new service. Does nothing.
-@item @file{ats/} --- Automatic Transport Selection
-The automatic transport selection (ATS) service
-is responsible for deciding which address (i.e.
-which transport plugin) should be used for communication with other peers,
-and at what bandwidth.
-@item @file{nat/} --- libgnunetnat
-Library that provides basic functions for NAT traversal.
-The library supports NAT traversal with
-manual hole-punching by the user, UPnP and ICMP-based autonomous NAT
-traversal. The library also includes an API for testing if the current
-configuration works and the @code{gnunet-nat-server} which provides an
-external service to test the local configuration.
-@item @file{fragmentation/} --- libgnunetfragmentation
-Some transports (UDP and WLAN, mostly) have restrictions on the maximum
-transfer unit (MTU) for packets. The fragmentation library can be used to
-break larger packets into chunks of at most 1k and transmit the resulting
-fragments reliably (with acknowledgment, retransmission, timeouts,
-etc.).
-@item @file{transport/} --- transport service
-The transport service is responsible for managing the
-basic P2P communication. It uses plugins to support P2P communication
-over TCP, UDP, HTTP, HTTPS and other protocols. The transport service
-validates peer addresses, enforces bandwidth restrictions, limits the
-total number of connections and enforces connectivity restrictions (e.g.
-friends-only).
-@item @file{peerinfo-tool/} --- gnunet-peerinfo
-This directory contains the gnunet-peerinfo binary which can be used to
-inspect the peers and HELLOs known to the peerinfo service.
-@item @file{core/}
-The core service is responsible for establishing encrypted, authenticated
-connections with other peers, encrypting and decrypting messages and
-forwarding messages to higher-level services that are interested in them.
-@item @file{testing/} --- libgnunettesting
-The testing library allows starting (and stopping) peers
-for writing testcases.
-It also supports automatic generation of configurations for peers
-ensuring that the ports and paths are disjoint. libgnunettesting is also
-the foundation for the testbed service
-@item @file{testbed/} --- testbed service
-The testbed service is used for creating small or large scale deployments
-of GNUnet peers for evaluation of protocols.
-It facilitates peer deployments on multiple
-hosts (for example, in a cluster) and establishing various network
-topologies (both underlay and overlay).
-@item @file{nse/} --- Network Size Estimation
-The network size estimation (NSE) service
-implements a protocol for (securely) estimating the current size of the
-P2P network.
-@item @file{dht/} --- distributed hash table
-The distributed hash table (DHT) service provides a
-distributed implementation of a hash table to store blocks under hash
-keys in the P2P network.
-@item @file{hostlist/} --- hostlist service
-The hostlist service allows learning about
-other peers in the network by downloading HELLO messages from an HTTP
-server, can be configured to run such an HTTP server and also implements
-a P2P protocol to advertise and automatically learn about other peers
-that offer a public hostlist server.
-@item @file{topology/} --- topology service
-The topology service is responsible for
-maintaining the mesh topology. It tries to maintain connections to friends
-(depending on the configuration) and also tries to ensure that the peer
-has a decent number of active connections at all times. If necessary, new
-connections are added. All peers should run the topology service,
-otherwise they may end up not being connected to any other peer (unless
-some other service ensures that core establishes the required
-connections). The topology service also tells the transport service which
-connections are permitted (for friend-to-friend networking)
-@item @file{fs/} --- file-sharing
-The file-sharing (FS) service implements GNUnet's
-file-sharing application. Both anonymous file-sharing (using gap) and
-non-anonymous file-sharing (using dht) are supported.
-@item @file{cadet/} --- cadet service
-The CADET service provides a general-purpose routing abstraction to create
-end-to-end encrypted tunnels in mesh networks. We wrote a paper
-documenting key aspects of the design.
-@item @file{tun/} --- libgnunettun
-Library for building IPv4, IPv6 packets and creating
-checksums for UDP, TCP and ICMP packets. The header
-defines C structs for common Internet packet formats and in particular
-structs for interacting with TUN (virtual network) interfaces.
-@item @file{mysql/} --- libgnunetmysql
-Library for creating and executing prepared MySQL
-statements and to manage the connection to the MySQL database.
-Essentially a lightweight wrapper for the interaction between GNUnet
-components and libmysqlclient.
-@item @file{dns/}
-Service that allows intercepting and modifying DNS requests of
-the local machine. Currently used for IPv4-IPv6 protocol translation
-(DNS-ALG) as implemented by "pt/" and for the GNUnet naming system. The
-service can also be configured to offer an exit service for DNS traffic.
-@item @file{vpn/} --- VPN service
-The virtual public network (VPN) service provides a virtual
-tunnel interface (VTUN) for IP routing over GNUnet.
-Needs some other peers to run an "exit" service to work.
-Can be activated using the "gnunet-vpn" tool or integrated with DNS using
-the "pt" daemon.
-@item @file{exit/}
-Daemon to allow traffic from the VPN to exit this
-peer to the Internet or to specific IP-based services of the local peer.
-Currently, an exit service can only be restricted to IPv4 or IPv6, not to
-specific ports and or IP address ranges. If this is not acceptable,
-additional firewall rules must be added manually. exit currently only
-works for normal UDP, TCP and ICMP traffic; DNS queries need to leave the
-system via a DNS service.
-@item @file{pt/}
-protocol translation daemon. This daemon enables 4-to-6,
-6-to-4, 4-over-6 or 6-over-4 transitions for the local system. It
-essentially uses "DNS" to intercept DNS replies and then maps results to
-those offered by the VPN, which then sends them using mesh to some daemon
-offering an appropriate exit service.
-@item @file{identity/}
-Management of egos (alter egos) of a user; identities are
-essentially named ECC private keys and used for zones in the GNU name
-system and for namespaces in file-sharing, but might find other uses later
-@item @file{revocation/}
-Key revocation service, can be used to revoke the
-private key of an identity if it has been compromised
-@item @file{namecache/}
-Cache for resolution results for the GNU name system;
-data is encrypted and can be shared among users,
-loss of the data should ideally only result in a
-performance degradation (persistence not required)
-@item @file{namestore/}
-Database for the GNU name system with per-user private information,
-persistence required
-@item @file{gns/}
-GNU name system, a GNU approach to DNS and PKI.
-@item @file{dv/}
-A plugin for distance-vector (DV)-based routing.
-DV consists of a service and a transport plugin to provide peers
-with the illusion of a direct P2P connection for connections
-that use multiple (typically up to 3) hops in the actual underlay network.
-@item @file{regex/}
-Service for the (distributed) evaluation of regular expressions.
-@item @file{scalarproduct/}
-The scalar product service offers an API to perform a secure multiparty
-computation which calculates a scalar product between two peers
-without exposing the private input vectors of the peers to each other.
-@item @file{consensus/}
-The consensus service will allow a set of peers to agree
-on a set of values via a distributed set union computation.
-@item @file{reclaim/}
-A decentralized personal data sharing service used to realize a decentralized
-identity provider. Supports OpenID Connect. See also @uref{https://reclaim.gnunet.org}.
-@item @file{rest/}
-The rest API allows access to GNUnet services using RESTful interaction.
-The services provide plugins that can exposed by the rest server.
-@c FIXME: Where did this disappear to?
-@c @item @file{experimentation/}
-@c The experimentation daemon coordinates distributed
-@c experimentation to evaluate transport and ATS properties.
-@end table
-@c ***********************************************************************
-@node System Architecture
-@section System Architecture
-@c FIXME: For those irritated by the textflow, we are missing images here,
-@c in the short term we should add them back, in the long term this should
-@c work without images or have images with alt-text.
-GNUnet developers like LEGOs. The blocks are indestructible, can be
-stacked together to construct complex buildings and it is generally easy
-to swap one block for a different one that has the same shape. GNUnet's
-architecture is based on LEGOs:
-@image{images/service_lego_block,5in,,picture of a LEGO block stack - 3 APIs upon IPC/network protocol provided by a service}
-This chapter documents the GNUnet LEGO system, also known as GNUnet's
-system architecture.
-The most common GNUnet component is a service. Services offer an API (or
-several, depending on what you count as "an API") which is implemented as
-a library. The library communicates with the main process of the service
-using a service-specific network protocol. The main process of the service
-typically doesn't fully provide everything that is needed --- it has holes
-to be filled by APIs to other services.
-A special kind of component in GNUnet are user interfaces and daemons.
-Like services, they have holes to be filled by APIs of other services.
-Unlike services, daemons do not implement their own network protocol and
-they have no API:
-@image{images/daemon_lego_block,5in,,A daemon in GNUnet is a component that does not offer an API for others to build upon}
-The GNUnet system provides a range of services, daemons and user
-interfaces, which are then combined into a layered GNUnet instance (also
-known as a peer).
-@image{images/service_stack,5in,,A GNUnet peer consists of many layers of services}
-Note that while it is generally possible to swap one service for another
-compatible service, there is often only one implementation. However,
-during development we often have a "new" version of a service in parallel
-with an "old" version. While the "new" version is not working, developers
-working on other parts of the service can continue their development by
-simply using the "old" service. Alternative design ideas can also be
-easily investigated by swapping out individual components. This is
-typically achieved by simply changing the name of the "BINARY" in the
-respective configuration section.
-Key properties of GNUnet services are that they must be separate
-processes and that they must protect themselves by applying tight error
-checking against the network protocol they implement (thereby achieving a
-certain degree of robustness).
-On the other hand, the APIs are implemented to tolerate failures of the
-service, isolating their host process from errors by the service. If the
-service process crashes, other services and daemons around it should not
-also fail, but instead wait for the service process to be restarted by
-ARM.
-@c ***********************************************************************
-@node Subsystem stability
-@section Subsystem stability
-This section documents the current stability of the various GNUnet
-subsystems. Stability here describes the expected degree of compatibility
-with future versions of GNUnet. For each subsystem we distinguish between
-compatibility on the P2P network level (communication protocol between
-peers), the IPC level (communication between the service and the service
-library) and the API level (stability of the API). P2P compatibility is
-relevant in terms of which applications are likely going to be able to
-communicate with future versions of the network. IPC communication is
-relevant for the implementation of language bindings that re-implement the
-IPC messages. Finally, API compatibility is relevant to developers that
-hope to be able to avoid changes to applications build on top of the APIs
-of the framework.
-The following table summarizes our current view of the stability of the
-respective protocols or APIs:
-@multitable @columnfractions .20 .20 .20 .20
-@headitem Subsystem @tab P2P @tab IPC @tab C API
-@item util @tab n/a @tab n/a @tab stable
-@item arm @tab n/a @tab stable @tab stable
-@item ats @tab n/a @tab unstable @tab testing
-@item block @tab n/a @tab n/a @tab stable
-@item cadet @tab testing @tab testing @tab testing
-@item consensus @tab experimental @tab experimental @tab experimental
-@item core @tab stable @tab stable @tab stable
-@item datacache @tab n/a @tab n/a @tab stable
-@item datastore @tab n/a @tab stable @tab stable
-@item dht @tab stable @tab stable @tab stable
-@item dns @tab stable @tab stable @tab stable
-@item dv @tab testing @tab testing @tab n/a
-@item exit @tab testing @tab n/a @tab n/a
-@item fragmentation @tab stable @tab n/a @tab stable
-@item fs @tab stable @tab stable @tab stable
-@item gns @tab stable @tab stable @tab stable
-@item hello @tab n/a @tab n/a @tab testing
-@item hostlist @tab stable @tab stable @tab n/a
-@item identity @tab stable @tab stable @tab n/a
-@item multicast @tab experimental @tab experimental @tab experimental
-@item mysql @tab stable @tab n/a @tab stable
-@item namestore @tab n/a @tab stable @tab stable
-@item nat @tab n/a @tab n/a @tab stable
-@item nse @tab stable @tab stable @tab stable
-@item peerinfo @tab n/a @tab stable @tab stable
-@item psyc @tab experimental @tab experimental @tab experimental
-@item pt @tab n/a @tab n/a @tab n/a
-@item regex @tab stable @tab stable @tab stable
-@item revocation @tab stable @tab stable @tab stable
-@item social @tab experimental @tab experimental @tab experimental
-@item statistics @tab n/a @tab stable @tab stable
-@item testbed @tab n/a @tab testing @tab testing
-@item testing @tab n/a @tab n/a @tab testing
-@item topology @tab n/a @tab n/a @tab n/a
-@item transport @tab experimental @tab experimental @tab experimental
-@item tun @tab n/a @tab n/a @tab stable
-@item vpn @tab testing @tab n/a @tab n/a
-@end multitable
-Here is a rough explanation of the values:
-@table @samp
-@item stable
-No incompatible changes are planned at this time; for IPC/APIs, if
-there are incompatible changes, they will be minor and might only require
-minimal changes to existing code; for P2P, changes will be avoided if at
-all possible for the 0.10.x-series
-@item testing
-No incompatible changes are
-planned at this time, but the code is still known to be in flux; so while
-we have no concrete plans, our expectation is that there will still be
-minor modifications; for P2P, changes will likely be extensions that
-should not break existing code
-@item unstable
-Changes are planned and will happen; however, they
-will not be totally radical and the result should still resemble what is
-there now; nevertheless, anticipated changes will break protocol/API
-compatibility
-@item experimental
-Changes are planned and the result may look nothing like
-what the API/protocol looks like today
-@item unknown
-Someone should think about where this subsystem headed
-@item n/a
-This subsystem does not have an API/IPC-protocol/P2P-protocol
-@end table
-@c ***********************************************************************
-@node Naming conventions and coding style guide
-@section Naming conventions and coding style guide
-Here you can find some rules to help you write code for GNUnet.
-@c ***********************************************************************
-@menu
-* Naming conventions::
-* Coding style::
-* Continuous integration::
-* Commit messages and developer branches::
-@end menu
-@node Naming conventions
-@subsection Naming conventions
-@c ***********************************************************************
-@menu
-* include files::
-* binaries::
-* logging::
-* configuration::
-* exported symbols::
-* private (library-internal) symbols (including structs and macros)::
-* testcases::
-* performance tests::
-* src/ directories::
-@end menu
-@node include files
-@subsubsection include files
-@itemize @bullet
-@item _lib: library without need for a process
-@item _service: library that needs a service process
-@item _plugin: plugin definition
-@item _protocol: structs used in network protocol
-@item exceptions:
-@itemize @bullet
-@item gnunet_config.h --- generated
-@item platform.h --- first included
-@item gnunet_common.h --- fundamental routines
-@item gnunet_directories.h --- generated
-@item gettext.h --- external library
-@end itemize
-@end itemize
-@c ***********************************************************************
-@node binaries
-@subsubsection binaries
-@itemize @bullet
-@item gnunet-service-xxx: service process (has listen socket)
-@item gnunet-daemon-xxx: daemon process (no listen socket)
-@item gnunet-helper-xxx[-yyy]: SUID helper for module xxx
-@item gnunet-yyy: command-line tool for end-users
-@item libgnunet_plugin_xxx_yyy.so: plugin for API xxx
-@item libgnunetxxx.so: library for API xxx
-@end itemize
-@c ***********************************************************************
-@node logging
-@subsubsection logging
-@itemize @bullet
-@item services and daemons use their directory name in
-@code{GNUNET_log_setup} (e.g. 'core') and log using
-plain 'GNUNET_log'.
-@item command-line tools use their full name in
-@code{GNUNET_log_setup} (e.g. 'gnunet-publish') and log using
-plain 'GNUNET_log'.
-@item service access libraries log using
-'@code{GNUNET_log_from}' and use '@code{DIRNAME-api}' for the
-component (e.g. 'core-api')
-@item pure libraries (without associated service) use
-'@code{GNUNET_log_from}' with the component set to their
-library name (without lib or '@file{.so}'),
-which should also be their directory name (e.g. '@file{nat}')
-@item plugins should use '@code{GNUNET_log_from}'
-with the directory name and the plugin name combined to produce
-the component name (e.g. 'transport-tcp').
-@item logging should be unified per-file by defining a
-@code{LOG} macro with the appropriate arguments,
-along these lines:
-@example
-#define LOG(kind,...)
-GNUNET_log_from (kind, "example-api",__VA_ARGS__)
-@end example
-@end itemize
-@c ***********************************************************************
-@node configuration
-@subsubsection configuration
-@itemize @bullet
-@item paths (that are substituted in all filenames) are in PATHS
-(have as few as possible)
-@item all options for a particular module (@file{src/MODULE})
-are under @code{[MODULE]}
-@item options for a plugin of a module
-are under @code{[MODULE-PLUGINNAME]}
-@end itemize
-@c ***********************************************************************
-@node exported symbols
-@subsubsection exported symbols
-@itemize @bullet
-@item must start with @code{GNUNET_modulename_} and be defined in
-@file{modulename.c}
-@item exceptions: those defined in @file{gnunet_common.h}
-@end itemize
-@c ***********************************************************************
-@node private (library-internal) symbols (including structs and macros)
-@subsubsection private (library-internal) symbols (including structs and macros)
-@itemize @bullet
-@item must NOT start with any prefix
-@item must not be exported in a way that linkers could use them or@ other
-libraries might see them via headers; they must be either
-declared/defined in C source files or in headers that are in the
-respective directory under @file{src/modulename/} and NEVER be declared
-in @file{src/include/}.
-@end itemize
-@node testcases
-@subsubsection testcases
-@itemize @bullet
-@item must be called @file{test_module-under-test_case-description.c}
-@item "case-description" maybe omitted if there is only one test
-@end itemize
-@c ***********************************************************************
-@node performance tests
-@subsubsection performance tests
-@itemize @bullet
-@item must be called @file{perf_module-under-test_case-description.c}
-@item "case-description" maybe omitted if there is only one performance
-test
-@item Must only be run if @code{HAVE_BENCHMARKS} is satisfied
-@end itemize
-@c ***********************************************************************
-@node src/ directories
-@subsubsection src/ directories
-@itemize @bullet
-@item gnunet-NAME: end-user applications (like gnunet-search or gnunet-arm)
-@item gnunet-service-NAME: service processes with accessor library (e.g.
-gnunet-service-arm)
-@item libgnunetNAME: accessor library (_service.h-header) or standalone
-library (_lib.h-header)
-@item gnunet-daemon-NAME: daemon process without accessor library (e.g.
-gnunet-daemon-hostlist) and no GNUnet management port
-@item libgnunet_plugin_DIR_NAME: loadable plugins (e.g.
-libgnunet_plugin_transport_tcp)
-@end itemize
-@cindex Coding style
-@node Coding style
-@subsection Coding style
-@c XXX: Adjust examples to GNU Standards!
-@itemize @bullet
-@item We follow the GNU Coding Standards (@pxref{Top, The GNU Coding Standards,, standards, The GNU Coding Standards});
-@item Indentation is done with spaces, two per level, no tabs; specific (incomplete!) indentation rules are provided in an @code{uncrustify} configuration file (in ``contrib/``) and enforced by Git hooks;
-@item C99 struct initialization is fine and generally encouraged (but not required);
-@item As in all good C code, we care about symbol space pollution and thus use @code{static} to limit the scope where possible, even in the compilation unit that contains @code{main};
-@item declare only one variable per line, for example:
-@noindent
-instead of
-@example
-int i,j;
-@end example
-@noindent
-write:
-@example
-int i;
-int j;
-@end example
-@c TODO: include actual example from a file in source
-@noindent
-This helps keep diffs small and forces developers to think precisely about
-the type of every variable.
-Note that @code{char *} is different from @code{const char*} and
-@code{int} is different from @code{unsigned int} or @code{uint32_t}.
-Each variable type should be chosen with care.
-@item While @code{goto} should generally be avoided, having a
-@code{goto} to the end of a function to a block of clean up
-statements (free, close, etc.) can be acceptable.
-@item Conditions should be written with constants on the left (to avoid
-accidental assignment) and with the @code{true} target being either the
-@code{error} case or the significantly simpler continuation. For example:
-@example
-if (0 != stat ("filename,"
-               &sbuf))
-@{
-  error();
-@}
-else
-@{
-  /* handle normal case here */
-@}
-@end example
-@noindent
-instead of
-@example
-if (stat ("filename," &sbuf) == 0) @{
-  /* handle normal case here */
- @} else @{
-  error();
- @}
-@end example
-@noindent
-If possible, the error clause should be terminated with a @code{return} (or
-@code{goto} to some cleanup routine) and in this case, the @code{else} clause
-should be omitted:
-@example
-if (0 != stat ("filename",
-               &sbuf))
-@{
-  error();
-  return;
-@}
-/* handle normal case here */
-@end example
-This serves to avoid deep nesting. The 'constants on the left' rule
-applies to all constants (including. @code{GNUNET_SCHEDULER_NO_TASK}),
-NULL, and enums). With the two above rules (constants on left, errors in
-'true' branch), there is only one way to write most branches correctly.
-@item Combined assignments and tests are allowed if they do not hinder
-code clarity. For example, one can write:
-@example
-if (NULL == (value = lookup_function()))
-@{
-  error();
-  return;
-@}
-@end example
-@item Use @code{break} and @code{continue} wherever possible to avoid
-deep(er) nesting. Thus, we would write:
-@example
-next = head;
-while (NULL != (pos = next))
-@{
-  next = pos->next;
-  if (! should_free (pos))
-    continue;
-  GNUNET_CONTAINER_DLL_remove (head,
-                               tail,
-                               pos);
-  GNUNET_free (pos);
-@}
-@end example
-instead of
-@example
-next = head; while (NULL != (pos = next)) @{
-  next = pos->next;
-  if (should_free (pos)) @{
-    /* unnecessary nesting! */
-    GNUNET_CONTAINER_DLL_remove (head, tail, pos);
-    GNUNET_free (pos);
-   @}
-  @}
-@end example
-@item We primarily use @code{for} and @code{while} loops.
-A @code{while} loop is used if the method for advancing in the loop is
-not a straightforward increment operation. In particular, we use:
-@example
-next = head;
-while (NULL != (pos = next))
-@{
-  next = pos->next;
-  if (! should_free (pos))
-    continue;
-  GNUNET_CONTAINER_DLL_remove (head,
-                               tail,
-                               pos);
-  GNUNET_free (pos);
-@}
-@end example
-to free entries in a list (as the iteration changes the structure of the
-list due to the free; the equivalent @code{for} loop does no longer
-follow the simple @code{for} paradigm of @code{for(INIT;TEST;INC)}).
-However, for loops that do follow the simple @code{for} paradigm we do
-use @code{for}, even if it involves linked lists:
-@example
-/* simple iteration over a linked list */
-for (pos = head;
-     NULL != pos;
-     pos = pos->next)
-@{
-   use (pos);
-@}
-@end example
-@item The first argument to all higher-order functions in GNUnet must be
-declared to be of type @code{void *} and is reserved for a closure. We do
-not use inner functions, as trampolines would conflict with setups that
-use non-executable stacks.
-The first statement in a higher-order function, which unusually should
-be part of the variable declarations, should assign the
-@code{cls} argument to the precise expected type. For example:
-@example
-int
-callback (void *cls,
-          char *args)
-@{
-  struct Foo *foo = cls;
-  int other_variables;
-   /* rest of function */
-@}
-@end example
-@item As shown in the example above, after the return type of a
-function there should be a break.  Each parameter should
-be on a new line.
-@item It is good practice to write complex @code{if} expressions instead
-of using deeply nested @code{if} statements. However, except for addition
-and multiplication, all operators should use parens. This is fine:
-@example
-if ( (1 == foo) ||
-     ( (0 == bar) &&
-       (x != y) ) )
-  return x;
-@end example
-However, this is not:
-@example
-if (1 == foo)
-  return x;
-if (0 == bar && x != y)
-  return x;
-@end example
-@noindent
-Note that splitting the @code{if} statement above is debatable as the
-@code{return x} is a very trivial statement. However, once the logic after
-the branch becomes more complicated (and is still identical), the "or"
-formulation should be used for sure.
-@item There should be two empty lines between the end of the function and
-the comments describing the following function. There should be a single
-empty line after the initial variable declarations of a function. If a
-function has no local variables, there should be no initial empty line. If
-a long function consists of several complex steps, those steps might be
-separated by an empty line (possibly followed by a comment describing the
-following step). The code should not contain empty lines in arbitrary
-places; if in doubt, it is likely better to NOT have an empty line (this
-way, more code will fit on the screen).
-@item When command-line arguments become too long (and would result in
-some particularly ugly @code{uncrustify} wrapping), we start all arguments
-on a new line. As a result, there must never be a new line within an
-argument declaration (i.e. between @code{struct} and the struct's name) or
-between the type and the variable). Example:
-@example
-struct GNUNET_TRANSPORT_CommunicatorHandle *
-GNUNET_TRANSPORT_communicator_connect (
-  const struct GNUNET_CONFIGURATION_Handle *cfg,
-  const char *config_section_name,
-  const char *addr_prefix,
-  ...);
-@end example
-Note that for short function names and arguments, the first argument
-does remain on the same line. Example:
-@example
-void
-fun (short i,
-     short j);
-@end example
-@end itemize
-@cindex Continuous integration
-@node Continuous integration
-@subsection Continuous integration
-The continuous integration buildbot can be found at @uref{https://buildbot.gnunet.org}.
-Repositories need to be enabled by a buildbot admin in order to participate
-in the builds.
-The buildbot can be configured to process scripts in your repository root under @code{.buildbot/}:
-The files @code{build.sh},  @code{install.sh} and @code{test.sh} are executed
-in order if present. If you want a specific worker to behave differently,
-you can provide a worker specific script, e.g. @code{myworker_build.sh}.
-In this case, the generic step will not be executed.
-For the @code{gnunet.git} repository, you may use "!tarball" or "!coverity" in
-your commit messages.
-"!tarball" will trigger a @code{make dist} of the gnunet source and verify that it
-can be compiled. The artifact will then be published to @uref{https://buildbot.gnunet.org/artifacts}.
-This is a good way to create a tarball for a release as it verifies the build
-on another machine.
-The "!coverity" trigger will trigger a coverity build and submit the results
-for analysis to coverity: @uref{https://scan.coverity.com/}.
-Only developers with accounts for the GNUnet project on coverity.com are able to
-see the analysis results.
-@cindex Commit messages and developer branches
-@node Commit messages and developer branches
-@subsection Commit messages and developer branches
-You can find the GNUnet project repositories at @uref{https://git.gnunet.org}.
-For each release, the ChangeLog file is generated from the commit history.
-Hence, commit messages are required to convey what changes were made in
-a self-contained fashion. Commit messages such as "fix" or "cleanup" are
-not acceptable.
-You commit message should ideally start with the subsystem name and be followed
-by a succinct description of the change. Where applicable a reference to
-a bug number in the bugtracker may also be included.
-Example:
-@example
-# <subsystem>: <description>. (#XXXX)
-IDENTITY: Fix wrong key construction for anonymous ECDSA identity. (Fixes #12344)
-@end example
-If you need to commit a minor fix you may prefix the commit message with a
-dash. It will then be ignored when generating the ChangeLog entries:
-@example
-# -<text>
-fix
-@end example
-If you need to modify a commit you can do so using:
-@example
-$ git commit --amend
-@end example
-If you need to modify a number of successive commits you will have to rebase
-and squash.
-Note that most branches are protected. This means that you can only fix commits
-as long as they are not pushed. You can only modify pushed commits in your own
-developer branches.
-A developer branch is a branch which matches a developer-specific prefix.
-As a developer with git access, you should have a git username. If you do not
-know it, please ask an admin.
-A developer branch has the format:
-@example
-dev/<username>/<branchname>
-@end example
-Assuming the developer with username "jdoe" wants to create a new branch for an
-i18n fix, the branch name could be:
-@example
-dev/jdoe/i18n_fx
-@end example
-The developer will be able to force push to and delete branches under his prefix.
-It is highly recommended to work in your own developer branches.
-Code which conforms to the commit message guidelines and coding style, is tested
-and builds may be merged to the master branch.
-Preferably, you would then...
-@itemize
-@item ...squash your commits,
-@item rebase to master and then
-@item merge your branch.
-@item (optional) Delete the branch.
-@end itemize
-In general, you may want to follow the rule "commit often, push tidy":
-You can create smaller, succinct commits with limited meaning on the commit
-messages. In the end and before you push or merge your branch, you
-can then squash the commits or rename them.
-@c ***********************************************************************
-@node Build-system
-@section Build-system
-If you have code that is likely not to compile or build rules you might
-want to not trigger for most developers, use @code{if HAVE_EXPERIMENTAL}
-in your @file{Makefile.am}.
-Then it is OK to (temporarily) add non-compiling (or known-to-not-port)
-code.
-If you want to compile all testcases but NOT run them, run configure with
-the @code{--enable-test-suppression} option.
-If you want to run all testcases, including those that take a while, run
-configure with the @code{--enable-expensive-testcases} option.
-If you want to compile and run benchmarks, run configure with the
-@code{--enable-benchmarks} option.
-If you want to obtain code coverage results, run configure with the
-@code{--enable-coverage} option and run the @file{coverage.sh} script in
-the @file{contrib/} directory.
-@cindex gnunet-ext
-@node Developing extensions for GNUnet using the gnunet-ext template
-@section Developing extensions for GNUnet using the gnunet-ext template
-For developers who want to write extensions for GNUnet we provide the
-gnunet-ext template to provide an easy to use skeleton.
-gnunet-ext contains the build environment and template files for the
-development of GNUnet services, command line tools, APIs and tests.
-First of all you have to obtain gnunet-ext from git:
-@example
-git clone https://git.gnunet.org/gnunet-ext.git
-@end example
-The next step is to bootstrap and configure it. For configure you have to
-provide the path containing GNUnet with
-@code{--with-gnunet=/path/to/gnunet} and the prefix where you want the
-install the extension using @code{--prefix=/path/to/install}:
-@example
-./bootstrap
-./configure --prefix=/path/to/install --with-gnunet=/path/to/gnunet
-@end example
-When your GNUnet installation is not included in the default linker search
-path, you have to add @code{/path/to/gnunet} to the file
-@file{/etc/ld.so.conf} and run @code{ldconfig} or your add it to the
-environmental variable @code{LD_LIBRARY_PATH} by using
-@example
-export LD_LIBRARY_PATH=/path/to/gnunet/lib
-@end example
-@cindex writing testcases
-@node Writing testcases
-@section Writing testcases
-Ideally, any non-trivial GNUnet code should be covered by automated
-testcases. Testcases should reside in the same place as the code that is
-being tested. The name of source files implementing tests should begin
-with @code{test_} followed by the name of the file that contains
-the code that is being tested.
-Testcases in GNUnet should be integrated with the autotools build system.
-This way, developers and anyone building binary packages will be able to
-run all testcases simply by running @code{make check}. The final
-testcases shipped with the distribution should output at most some brief
-progress information and not display debug messages by default. The
-success or failure of a testcase must be indicated by returning zero
-(success) or non-zero (failure) from the main method of the testcase.
-The integration with the autotools is relatively straightforward and only
-requires modifications to the @file{Makefile.am} in the directory
-containing the testcase. For a testcase testing the code in @file{foo.c}
-the @file{Makefile.am} would contain the following lines:
-@example
-check_PROGRAMS = test_foo
-TESTS = $(check_PROGRAMS)
-test_foo_SOURCES = test_foo.c
-test_foo_LDADD = $(top_builddir)/src/util/libgnunetutil.la
-@end example
-Naturally, other libraries used by the testcase may be specified in the
-@code{LDADD} directive as necessary.
-Often testcases depend on additional input files, such as a configuration
-file. These support files have to be listed using the @code{EXTRA_DIST}
-directive in order to ensure that they are included in the distribution.
-Example:
-@example
-EXTRA_DIST = test_foo_data.conf
-@end example
-Executing @code{make check} will run all testcases in the current
-directory and all subdirectories. Testcases can be compiled individually
-by running @code{make test_foo} and then invoked directly using
-@code{./test_foo}. Note that due to the use of plugins in GNUnet, it is
-typically necessary to run @code{make install} before running any
-testcases. Thus the canonical command @code{make check install} has to be
-changed to @code{make install check} for GNUnet.
-@c ***********************************************************************
-@cindex Building GNUnet
-@node Building GNUnet and its dependencies
-@section Building GNUnet and its dependencies
-In the following section we will outline how to build GNUnet and
-some of its dependencies. We will assume a fair amount of knowledge
-for building applications under UNIX-like systems. Furthermore we
-assume that the build environment is sane and that you are aware of
-any implications actions in this process could have.
-Instructions here can be seen as notes for developers (an extension to
-the 'HACKING' section in README) as well as package maintainers.
-@b{Users should rely on the available binary packages.}
-We will use Debian as an example Operating System environment. Substitute
-accordingly with your own Operating System environment.
-For the full list of dependencies, consult the appropriate, up-to-date
-section in the @file{README} file.
-@example
-libgpgerror, libgcrypt, libnettle, libunbound, GnuTLS (with libunbound
-support)
-@end example
-After we have build and installed those packages, we continue with
-packages closer to GNUnet in this step: libgnurl (our libcurl fork),
-GNU libmicrohttpd, and GNU libextractor. Again, if your package manager
-provides one of these packages, use the packages provided from it
-unless you have good reasons (package version too old, conflicts, etc).
-We advise against compiling widely used packages such as GnuTLS
-yourself if your OS provides a variant already unless you take care
-of maintenance of the packages then.
-In the optimistic case, this command will give you all the dependencies
-on Debian, Debian derived systems or any Linux Operating System using
-the apt package manager:
-@example
-sudo apt-get install libgnurl libmicrohttpd libextractor
-@end example
-From experience we know that at the very least libgnurl is not
-available in some environments. You could substitute libgnurl
-with libcurl, but we recommend to install libgnurl, as it gives
-you a predefined libcurl with the small set GNUnet requires.
-libgnurl has been developed to co-exist with libcurl installations,
-installing it will cause no filename or namespace collisions.
-@cindex libgnurl
-@cindex compiling libgnurl
-GNUnet and some of its function depend on a limited subset of cURL/libcurl.
-Rather than trying to enforce a certain configuration on the world, we
-opted to maintain a microfork of it that ensures that we can link
-against the right set of features.
-We called this specialized set of libcurl "libgnurl".
-It is fully ABI compatible with libcurl and currently used by
-GNUnet and some of its dependencies.
-We download libgnurl and its digital signature from the GNU fileserver,
-assuming @env{TMPDIR} exists.
-@quotation
-Note: TMPDIR might be @file{/tmp}, @env{TMPDIR}, @env{TMP} or any other
-location. For consistency we assume @env{TMPDIR} points to @file{/tmp}
-for the remainder of this section.
-@end quotation
-@example
-cd \$TMPDIR
-wget https://ftp.gnu.org/gnu/gnunet/gnurl-7.65.3.tar.Z
-wget https://ftp.gnu.org/gnu/gnunet/gnurl-7.65.3.tar.Z.sig
-@end example
-Next, verify the digital signature of the file:
-@example
-gpg --verify gnurl-7.65.3.tar.Z.sig
-@end example
-If gpg fails, you might try with @command{gpg2} on your OS. If the error
-states that ``the key can not be found'' or it is unknown, you have to
-retrieve the key (A88C8ADD129828D7EAC02E52E22F9BBFEE348588) from a
-keyserver first:
-@example
-gpg --keyserver pgp.mit.edu --recv-keys A88C8ADD129828D7EAC02E52E22F9BBFEE348588
-@end example
-or
-@example
-gpg --keyserver hkps://keys.openpgp.org --recv-keys A88C8ADD129828D7EAC02E52E22F9BBFEE348588
-@end example
-and rerun the verification command.
-libgnurl will require the following packages to be present at runtime:
-GnuTLS (with DANE support / libunbound), libidn, zlib and at compile time:
-libtool, perl, pkg-config, and (for tests) python (2.7, or
-any version of python 3).
-Once you have verified that all the required packages are present on your
-system, we can proceed to compile libgnurl. This assumes you will install
-gnurl in the default location as prefix. To change this, pass --prefix= to
-the configure-gnurl script (which is a simple wrapper around configure).
-@example
-tar -xvf gnurl-7.65.3.tar.Z
-cd gnurl-7.65.3
-sh ./configure-gnurl
-make
-make -C tests test
-sudo make install
-@end example
-After you've compiled and installed libgnurl, we can proceed to building
-GNUnet.
-First, in addition to the GNUnet sources you might require downloading the
-latest version of various dependencies, depending on how recent the
-software versions in your distribution of GNU/Linux are.
-Most distributions do not include sufficiently recent versions of these
-dependencies.
-Thus, a typically installation on a "modern" GNU/Linux distribution
-requires you to install the following dependencies (ideally in this
-order):
-@itemize @bullet
-@item libgpgerror and libgcrypt
-@item libnettle and libunbound (possibly from distribution), GnuTLS
-@item libgnurl (read the README)
-@item GNU libmicrohttpd
-@item GNU libextractor
-@end itemize
-Make sure to first install the various mandatory and optional
-dependencies including development headers from your distribution.
-Other dependencies that you should strongly consider to install is a
-database (MySQL, SQLite3 or Postgres).
-The following instructions will assume that you installed at least
-SQLite3 (commonly distributed as ``sqlite'' or ``sqlite3'').
-For most distributions you should be able to find pre-build packages for
-the database. Again, make sure to install the client libraries @b{and} the
-respective development headers (if they are packaged separately) as well.
-@c TODO: Do these platform specific descriptions still exist? If not,
-@c we should find a way to sync website parts with this texinfo.
-You can find specific, detailed instructions for installing of the
-dependencies (and possibly the rest of the GNUnet installation) in the
-platform-specific descriptions, which can be found in the Index.
-Please consult them now.
-If your distribution is not listed, please study the build
-instructions for Debian stable, carefully as you try to install the
-dependencies for your own distribution.
-Contributing additional instructions for further platforms is always
-appreciated.
-Please take in mind that operating system development tends to move at
-a rather fast speed. Due to this you should be aware that some of
-the instructions could be outdated by the time you are reading this.
-If you find a mistake, please tell us about it (or even better: send
-a patch to the documentation to fix it!).
-Before proceeding further, please double-check the dependency list.
-Note that in addition to satisfying the dependencies, you might have to
-make sure that development headers for the various libraries are also
-installed.
-There maybe files for other distributions, or you might be able to find
-equivalent packages for your distribution.
-While it is possible to build and install GNUnet without having root
-access, we will assume that you have full control over your system in
-these instructions.
-First, you should create a system user @emph{gnunet} and an additional
-group @emph{gnunetdns}. On the GNU/Linux distributions Debian and Ubuntu,
-type:
-@example
-sudo adduser --system --home /var/lib/gnunet --group \
--disabled-password gnunet
-sudo addgroup --system gnunetdns
-@end example
-@noindent
-On other Unix-like systems, this should have the same effect:
-@example
-sudo useradd --system --groups gnunet --home-dir /var/lib/gnunet
-sudo addgroup --system gnunetdns
-@end example
-Now compile and install GNUnet using:
-@example
-tar xvf gnunet-@value{VERSION}.tar.gz
-cd gnunet-@value{VERSION}
-./configure --with-sudo=sudo --with-nssdir=/lib
-make
-sudo make install
-@end example
-If you want to be able to enable DEBUG-level log messages, add
-@code{--enable-logging=verbose} to the end of the
-@command{./configure} command.
-@code{DEBUG}-level log messages are in English only and
-should only be useful for developers (or for filing
-really detailed bug reports).
-@noindent
-Next, edit the file @file{/etc/gnunet.conf} to contain the following:
-@example
-[arm]
-START_SYSTEM_SERVICES = YES
-START_USER_SERVICES = NO
-@end example
-@noindent
-You may need to update your @code{ld.so} cache to include
-files installed in @file{/usr/local/lib}:
-@example
-# ldconfig
-@end example
-@noindent
-Then, switch from user @code{root} to user @code{gnunet} to start
-the peer:
-@example
-# su -s /bin/sh - gnunet
-$ gnunet-arm -c /etc/gnunet.conf -s
-@end example
-You may also want to add the last line in the gnunet user's @file{crontab}
-prefixed with @code{@@reboot} so that it is executed whenever the system
-is booted:
-@example
-@@reboot /usr/local/bin/gnunet-arm -c /etc/gnunet.conf -s
-@end example
-@noindent
-This will only start the system-wide GNUnet services.
-Type @command{exit} to get back your root shell.
-Now, you need to configure the per-user part. For each
-user that should get access to GNUnet on the system, run
-(replace alice with your username):
-@example
-sudo adduser alice gnunet
-@end example
-@noindent
-to allow them to access the system-wide GNUnet services. Then, each
-user should create a configuration file @file{~/.config/gnunet.conf}
-with the lines:
-@example
-[arm]
-START_SYSTEM_SERVICES = NO
-START_USER_SERVICES = YES
-DEFAULTSERVICES = gns
-@end example
-@noindent
-and start the per-user services using
-@example
-$ gnunet-arm -c ~/.config/gnunet.conf -s
-@end example
-@noindent
-Again, adding a @code{crontab} entry to autostart the peer is advised:
-@example
-@@reboot /usr/local/bin/gnunet-arm -c $HOME/.config/gnunet.conf -s
-@end example
-@noindent
-Note that some GNUnet services (such as socks5 proxies) may need a
-system-wide TCP port for each user.
-For those services, systems with more than one user may require each user
-to specify a different port number in their personal configuration file.
-Finally, the user should perform the basic initial setup for the GNU Name
-System (GNS) certificate authority. This is done by running:
-@example
-$ gnunet-gns-proxy-setup-ca
-@end example
-@noindent
-The first generates the default zones, whereas the second setups the GNS
-Certificate Authority with the user's browser. Now, to activate GNS in the
-normal DNS resolution process, you need to edit your
-@file{/etc/nsswitch.conf} where you should find a line like this:
-@example
-hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4
-@end example
-@noindent
-The exact details may differ a bit, which is fine. Add the text
-@emph{"gns [NOTFOUND=return]"} after @emph{"files"}.
-Keep in mind that we included a backslash ("\") here just for
-markup reasons. You should write the text below on @b{one line}
-and @b{without} the "\":
-@example
-hosts: files gns [NOTFOUND=return] mdns4_minimal \
-[NOTFOUND=return] dns mdns4
-@end example
-@c FIXME: Document new behavior.
-You might want to make sure that @file{/lib/libnss_gns.so.2} exists on
-your system, it should have been created during the installation.
-@c **********************************************************************
-@cindex TESTING library
-@node TESTING library
-@section TESTING library
-The TESTING library is used for writing testcases which involve starting a
-single or multiple peers. While peers can also be started by testcases
-using the ARM subsystem, using TESTING library provides an elegant way to
-do this. The configurations of the peers are auto-generated from a given
-template to have non-conflicting port numbers ensuring that peers'
-services do not run into bind errors. This is achieved by testing ports'
-availability by binding a listening socket to them before allocating them
-to services in the generated configurations.
-An another advantage while using TESTING is that it shortens the testcase
-startup time as the hostkeys for peers are copied from a pre-computed set
-of hostkeys instead of generating them at peer startup which may take a
-considerable amount of time when starting multiple peers or on an embedded
-processor.
-TESTING also allows for certain services to be shared among peers. This
-feature is invaluable when testing with multiple peers as it helps to
-reduce the number of services run per each peer and hence the total
-number of processes run per testcase.
-TESTING library only handles creating, starting and stopping peers.
-Features useful for testcases such as connecting peers in a topology are
-not available in TESTING but are available in the TESTBED subsystem.
-Furthermore, TESTING only creates peers on the localhost, however by
-using TESTBED testcases can benefit from creating peers across multiple
-hosts.
-@menu
-* API::
-* Finer control over peer stop::
-* Helper functions::
-* Testing with multiple processes::
-@end menu
-@cindex TESTING API
-@node API
-@subsection API
-TESTING abstracts a group of peers as a TESTING system. All peers in a
-system have common hostname and no two services of these peers have a
-same port or a UNIX domain socket path.
-TESTING system can be created with the function
-@code{GNUNET_TESTING_system_create()} which returns a handle to the
-system. This function takes a directory path which is used for generating
-the configurations of peers, an IP address from which connections to the
-peers' services should be allowed, the hostname to be used in peers'
-configuration, and an array of shared service specifications of type
-@code{struct GNUNET_TESTING_SharedService}.
-The shared service specification must specify the name of the service to
-share, the configuration pertaining to that shared service and the
-maximum number of peers that are allowed to share a single instance of
-the shared service.
-TESTING system created with @code{GNUNET_TESTING_system_create()} chooses
-ports from the default range @code{12000} - @code{56000} while
-auto-generating configurations for peers.
-This range can be customised with the function
-@code{GNUNET_TESTING_system_create_with_portrange()}. This function is
-similar to @code{GNUNET_TESTING_system_create()} except that it take 2
-additional parameters --- the start and end of the port range to use.
-A TESTING system is destroyed with the function
-@code{GNUNET_TESTING_system_destory()}. This function takes the handle of
-the system and a flag to remove the files created in the directory used
-to generate configurations.
-A peer is created with the function
-@code{GNUNET_TESTING_peer_configure()}. This functions takes the system
-handle, a configuration template from which the configuration for the peer
-is auto-generated and the index from where the hostkey for the peer has to
-be copied from. When successful, this function returns a handle to the
-peer which can be used to start and stop it and to obtain the identity of
-the peer. If unsuccessful, a NULL pointer is returned with an error
-message. This function handles the generated configuration to have
-non-conflicting ports and paths.
-Peers can be started and stopped by calling the functions
-@code{GNUNET_TESTING_peer_start()} and @code{GNUNET_TESTING_peer_stop()}
-respectively. A peer can be destroyed by calling the function
-@code{GNUNET_TESTING_peer_destroy}. When a peer is destroyed, the ports
-and paths in allocated in its configuration are reclaimed for usage in new
-peers.
-@c ***********************************************************************
-@node Finer control over peer stop
-@subsection Finer control over peer stop
-Using @code{GNUNET_TESTING_peer_stop()} is normally fine for testcases.
-However, calling this function for each peer is inefficient when trying to
-shutdown multiple peers as this function sends the termination signal to
-the given peer process and waits for it to terminate. It would be faster
-in this case to send the termination signals to the peers first and then
-wait on them. This is accomplished by the functions
-@code{GNUNET_TESTING_peer_kill()} which sends a termination signal to the
-peer, and the function @code{GNUNET_TESTING_peer_wait()} which waits on
-the peer.
-Further finer control can be achieved by choosing to stop a peer
-asynchronously with the function @code{GNUNET_TESTING_peer_stop_async()}.
-This function takes a callback parameter and a closure for it in addition
-to the handle to the peer to stop. The callback function is called with
-the given closure when the peer is stopped. Using this function
-eliminates blocking while waiting for the peer to terminate.
-An asynchronous peer stop can be canceled by calling the function
-@code{GNUNET_TESTING_peer_stop_async_cancel()}. Note that calling this
-function does not prevent the peer from terminating if the termination
-signal has already been sent to it. It does, however, cancels the
-callback to be called when the peer is stopped.
-@c ***********************************************************************
-@node Helper functions
-@subsection Helper functions
-Most of the testcases can benefit from an abstraction which configures a
-peer and starts it. This is provided by the function
-@code{GNUNET_TESTING_peer_run()}. This function takes the testing
-directory pathname, a configuration template, a callback and its closure.
-This function creates a peer in the given testing directory by using the
-configuration template, starts the peer and calls the given callback with
-the given closure.
-The function @code{GNUNET_TESTING_peer_run()} starts the ARM service of
-the peer which starts the rest of the configured services. A similar
-function @code{GNUNET_TESTING_service_run} can be used to just start a
-single service of a peer. In this case, the peer's ARM service is not
-started; instead, only the given service is run.
-@c ***********************************************************************
-@node Testing with multiple processes
-@subsection Testing with multiple processes
-When testing GNUnet, the splitting of the code into a services and clients
-often complicates testing. The solution to this is to have the testcase
-fork @code{gnunet-service-arm}, ask it to start the required server and
-daemon processes and then execute appropriate client actions (to test the
-client APIs or the core module or both). If necessary, multiple ARM
-services can be forked using different ports (!) to simulate a network.
-However, most of the time only one ARM process is needed. Note that on
-exit, the testcase should shutdown ARM with a @code{TERM} signal (to give
-it the chance to cleanly stop its child processes).
-@c TODO: Is this still compiling and working as intended?
-The following code illustrates spawning and killing an ARM process from a
-testcase:
-@example
-static void run (void *cls,
-                 char *const *args,
-                 const char *cfgfile,
-                 const struct GNUNET_CONFIGURATION_Handle *cfg) @{
-  struct GNUNET_OS_Process *arm_pid;
-  arm_pid = GNUNET_OS_start_process (NULL,
-                                     NULL,
-                                     "gnunet-service-arm",
-                                     "gnunet-service-arm",
-                                     "-c",
-                                     cfgname,
-                                     NULL);
-  /* do real test work here */
-  if (0 != GNUNET_OS_process_kill (arm_pid, SIGTERM))
-    GNUNET_log_strerror
-      (GNUNET_ERROR_TYPE_WARNING, "kill");
-  GNUNET_assert (GNUNET_OK == GNUNET_OS_process_wait (arm_pid));
-  GNUNET_OS_process_close (arm_pid); @}
-GNUNET_PROGRAM_run (argc, argv,
-                    "NAME-OF-TEST",
-                    "nohelp",
-                    options,
-                    &run,
-                    cls);
-@end example
-An alternative way that works well to test plugins is to implement a
-mock-version of the environment that the plugin expects and then to
-simply load the plugin directly.
-@c ***********************************************************************
-@node Performance regression analysis with Gauger
-@section Performance regression analysis with Gauger
-To help avoid performance regressions, GNUnet uses Gauger. Gauger is a
-simple logging tool that allows remote hosts to send performance data to
-a central server, where this data can be analyzed and visualized. Gauger
-shows graphs of the repository revisions and the performance data recorded
-for each revision, so sudden performance peaks or drops can be identified
-and linked to a specific revision number.
-In the case of GNUnet, the buildbots log the performance data obtained
-during the tests after each build. The data can be accessed on GNUnet's
-Gauger page.
-The menu on the left allows to select either the results of just one
-build bot (under "Hosts") or review the data from all hosts for a given
-test result (under "Metrics"). In case of very different absolute value
-of the results, for instance arm vs. amd64 machines, the option
-"Normalize" on a metric view can help to get an idea about the
-performance evolution across all hosts.
-Using Gauger in GNUnet and having the performance of a module tracked over
-time is very easy. First of course, the testcase must generate some
-consistent metric, which makes sense to have logged. Highly volatile or
-random dependent metrics probably are not ideal candidates for meaningful
-regression detection.
-To start logging any value, just include @code{gauger.h} in your testcase
-code. Then, use the macro @code{GAUGER()} to make the Buildbots log
-whatever value is of interest for you to @code{gnunet.org}'s Gauger
-server. No setup is necessary as most Buildbots have already everything
-in place and new metrics are created on demand. To delete a metric, you
-need to contact a member of the GNUnet development team (a file will need
-to be removed manually from the respective directory).
-The code in the test should look like this:
-@example
-[other includes]
-#include <gauger.h>
-int main (int argc, char *argv[]) @{
-  [run test, generate data]
-    GAUGER("YOUR_MODULE",
-           "METRIC_NAME",
-           (float)value,
-           "UNIT"); @}
-@end example
-Where:
-@table @asis
-@item @strong{YOUR_MODULE} is a category in the gauger page and should be
-the name of the module or subsystem like "Core" or "DHT"
-@item @strong{METRIC} is
-the name of the metric being collected and should be concise and
-descriptive, like "PUT operations in sqlite-datastore".
-@item @strong{value} is the value
-of the metric that is logged for this run.
-@item @strong{UNIT} is the unit in
-which the value is measured, for instance "kb/s" or "kb of RAM/node".
-@end table
-If you wish to use Gauger for your own project, you can grab a copy of the
-latest stable release or check out Gauger's Subversion repository.
-@cindex TESTBED Subsystem
-@node TESTBED Subsystem
-@section TESTBED Subsystem
-The TESTBED subsystem facilitates testing and measuring of multi-peer
-deployments on a single host or over multiple hosts.
-The architecture of the testbed module is divided into the following:
-@itemize @bullet
-@item Testbed API: An API which is used by the testing driver programs. It
-provides with functions for creating, destroying, starting, stopping
-peers, etc.
-@item Testbed service (controller): A service which is started through the
-Testbed API. This service handles operations to create, destroy, start,
-stop peers, connect them, modify their configurations.
-@item Testbed helper: When a controller has to be started on a host, the
-testbed API starts the testbed helper on that host which in turn starts
-the controller. The testbed helper receives a configuration for the
-controller through its stdin and changes it to ensure the controller
-doesn't run into any port conflict on that host.
-@end itemize
-The testbed service (controller) is different from the other GNUnet
-services in that it is not started by ARM and is not supposed to be run
-as a daemon. It is started by the testbed API through a testbed helper.
-In a typical scenario involving multiple hosts, a controller is started
-on each host. Controllers take up the actual task of creating peers,
-starting and stopping them on the hosts they run.
-While running deployments on a single localhost the testbed API starts the
-testbed helper directly as a child process. When running deployments on
-remote hosts the testbed API starts Testbed Helpers on each remote host
-through remote shell. By default testbed API uses SSH as a remote shell.
-This can be changed by setting the environmental variable
-GNUNET_TESTBED_RSH_CMD to the required remote shell program. This
-variable can also contain parameters which are to be passed to the remote
-shell program. For e.g:
-@example
-export GNUNET_TESTBED_RSH_CMD="ssh -o BatchMode=yes \
-o NoHostAuthenticationForLocalhost=yes %h"
-@end example
-Substitutions are allowed in the command string above,
-this allows for substitutions through placemarks which begin with a `%'.
-At present the following substitutions are supported
-@itemize @bullet
-@item %h: hostname
-@item %u: username
-@item %p: port
-@end itemize
-Note that the substitution placemark is replaced only when the
-corresponding field is available and only once. Specifying
-@example
-%u@@%h
-@end example
-doesn't work either. If you want to user username substitutions for
-@command{SSH}, use the argument @code{-l} before the
-username substitution.
-For example:
-@example
-ssh -l %u -p %p %h
-@end example
-The testbed API and the helper communicate through the helpers stdin and
-stdout. As the helper is started through a remote shell on remote hosts
-any output messages from the remote shell interfere with the communication
-and results in a failure while starting the helper. For this reason, it is
-suggested to use flags to make the remote shells produce no output
-messages and to have password-less logins. The default remote shell, SSH,
-the default options are:
-@example
-o BatchMode=yes -o NoHostBasedAuthenticationForLocalhost=yes"
-@end example
-Password-less logins should be ensured by using SSH keys.
-Since the testbed API executes the remote shell as a non-interactive
-shell, certain scripts like .bashrc, .profiler may not be executed. If
-this is the case testbed API can be forced to execute an interactive
-shell by setting up the environmental variable
-@code{GNUNET_TESTBED_RSH_CMD_SUFFIX} to a shell program.
-An example could be:
-@example
-export GNUNET_TESTBED_RSH_CMD_SUFFIX="sh -lc"
-@end example
-The testbed API will then execute the remote shell program as:
-@example
-$GNUNET_TESTBED_RSH_CMD -p $port $dest $GNUNET_TESTBED_RSH_CMD_SUFFIX \
-gnunet-helper-testbed
-@end example
-On some systems, problems may arise while starting testbed helpers if
-GNUnet is installed into a custom location since the helper may not be
-found in the standard path. This can be addressed by setting the variable
-`@code{HELPER_BINARY_PATH}' to the path of the testbed helper.
-Testbed API will then use this path to start helper binaries both
-locally and remotely.
-Testbed API can accessed by including the
-@file{gnunet_testbed_service.h} file and linking with
-@code{-lgnunettestbed}.
-@c ***********************************************************************
-@menu
-* Supported Topologies::
-* Hosts file format::
-* Topology file format::
-* Testbed Barriers::
-* TESTBED Caveats::
-@end menu
-@node Supported Topologies
-@subsection Supported Topologies
-While testing multi-peer deployments, it is often needed that the peers
-are connected in some topology. This requirement is addressed by the
-function @code{GNUNET_TESTBED_overlay_connect()} which connects any given
-two peers in the testbed.
-The API also provides a helper function
-@code{GNUNET_TESTBED_overlay_configure_topology()} to connect a given set
-of peers in any of the following supported topologies:
-@itemize @bullet
-@item @code{GNUNET_TESTBED_TOPOLOGY_CLIQUE}: All peers are connected with
-each other
-@item @code{GNUNET_TESTBED_TOPOLOGY_LINE}: Peers are connected to form a
-line
-@item @code{GNUNET_TESTBED_TOPOLOGY_RING}: Peers are connected to form a
-ring topology
-@item @code{GNUNET_TESTBED_TOPOLOGY_2D_TORUS}: Peers are connected to
-form a 2 dimensional torus topology. The number of peers may not be a
-perfect square, in that case the resulting torus may not have the uniform
-poloidal and toroidal lengths
-@item @code{GNUNET_TESTBED_TOPOLOGY_ERDOS_RENYI}: Topology is generated
-to form a random graph. The number of links to be present should be given
-@item @code{GNUNET_TESTBED_TOPOLOGY_SMALL_WORLD}: Peers are connected to
-form a 2D Torus with some random links among them. The number of random
-links are to be given
-@item @code{GNUNET_TESTBED_TOPOLOGY_SMALL_WORLD_RING}: Peers are
-connected to form a ring with some random links among them. The number of
-random links are to be given
-@item @code{GNUNET_TESTBED_TOPOLOGY_SCALE_FREE}: Connects peers in a
-topology where peer connectivity follows power law - new peers are
-connected with high probability to well connected peers.
-(See Emergence of Scaling in Random Networks. Science 286,
-509-512, 1999
-(@uref{https://git.gnunet.org/bibliography.git/plain/docs/emergence_of_scaling_in_random_networks__barabasi_albert_science_286__1999.pdf, pdf}))
-@item @code{GNUNET_TESTBED_TOPOLOGY_FROM_FILE}: The topology information
-is loaded from a file. The path to the file has to be given.
-@xref{Topology file format}, for the format of this file.
-@item @code{GNUNET_TESTBED_TOPOLOGY_NONE}: No topology
-@end itemize
-The above supported topologies can be specified respectively by setting
-the variable @code{OVERLAY_TOPOLOGY} to the following values in the
-configuration passed to Testbed API functions
-@code{GNUNET_TESTBED_test_run()} and
-@code{GNUNET_TESTBED_run()}:
-@itemize @bullet
-@item @code{CLIQUE}
-@item @code{RING}
-@item @code{LINE}
-@item @code{2D_TORUS}
-@item @code{RANDOM}
-@item @code{SMALL_WORLD}
-@item @code{SMALL_WORLD_RING}
-@item @code{SCALE_FREE}
-@item @code{FROM_FILE}
-@item @code{NONE}
-@end itemize
-Topologies @code{RANDOM}, @code{SMALL_WORLD} and @code{SMALL_WORLD_RING}
-require the option @code{OVERLAY_RANDOM_LINKS} to be set to the number of
-random links to be generated in the configuration. The option will be
-ignored for the rest of the topologies.
-Topology @code{SCALE_FREE} requires the options
-@code{SCALE_FREE_TOPOLOGY_CAP} to be set to the maximum number of peers
-which can connect to a peer and @code{SCALE_FREE_TOPOLOGY_M} to be set to
-how many peers a peer should be at least connected to.
-Similarly, the topology @code{FROM_FILE} requires the option
-@code{OVERLAY_TOPOLOGY_FILE} to contain the path of the file containing
-the topology information. This option is ignored for the rest of the
-topologies. @xref{Topology file format}, for the format of this file.
-@c ***********************************************************************
-@node Hosts file format
-@subsection Hosts file format
-The testbed API offers the function
-@code{GNUNET_TESTBED_hosts_load_from_file()} to load from a given file
-details about the hosts which testbed can use for deploying peers.
-This function is useful to keep the data about hosts
-separate instead of hard coding them in code.
-Another helper function from testbed API, @code{GNUNET_TESTBED_run()}
-also takes a hosts file name as its parameter. It uses the above
-function to populate the hosts data structures and start controllers to
-deploy peers.
-These functions require the hosts file to be of the following format:
-@itemize @bullet
-@item Each line is interpreted to have details about a host
-@item Host details should include the username to use for logging into the
-host, the hostname of the host and the port number to use for the remote
-shell program. All thee values should be given.
-@item These details should be given in the following format:
-@example
-<username>@@<hostname>:<port>
-@end example
-@end itemize
-Note that having canonical hostnames may cause problems while resolving
-the IP addresses (See this bug). Hence it is advised to provide the hosts'
-IP numerical addresses as hostnames whenever possible.
-@c ***********************************************************************
-@node Topology file format
-@subsection Topology file format
-A topology file describes how peers are to be connected. It should adhere
-to the following format for testbed to parse it correctly.
-Each line should begin with the target peer id. This should be followed by
-a colon(`:') and origin peer ids separated by `|'. All spaces except for
-newline characters are ignored. The API will then try to connect each
-origin peer to the target peer.
-For example, the following file will result in 5 overlay connections:
-[2->1], [3->1],[4->3], [0->3], [2->0]@
-@code{@ 1:2|3@ 3:4| 0@ 0: 2@ }
-@c ***********************************************************************
-@node Testbed Barriers
-@subsection Testbed Barriers
-The testbed subsystem's barriers API facilitates coordination among the
-peers run by the testbed and the experiment driver. The concept is
-similar to the barrier synchronisation mechanism found in parallel
-programming or multi-threading paradigms - a peer waits at a barrier upon
-reaching it until the barrier is reached by a predefined number of peers.
-This predefined number of peers required to cross a barrier is also called
-quorum. We say a peer has reached a barrier if the peer is waiting for the
-barrier to be crossed. Similarly a barrier is said to be reached if the
-required quorum of peers reach the barrier. A barrier which is reached is
-deemed as crossed after all the peers waiting on it are notified.
-The barriers API provides the following functions:
-@itemize @bullet
-@item @strong{@code{GNUNET_TESTBED_barrier_init()}:} function to
-initialize a barrier in the experiment
-@item @strong{@code{GNUNET_TESTBED_barrier_cancel()}:} function to cancel
-a barrier which has been initialized before
-@item @strong{@code{GNUNET_TESTBED_barrier_wait()}:} function to signal
-barrier service that the caller has reached a barrier and is waiting for
-it to be crossed
-@item @strong{@code{GNUNET_TESTBED_barrier_wait_cancel()}:} function to
-stop waiting for a barrier to be crossed
-@end itemize
-Among the above functions, the first two, namely
-@code{GNUNET_TESTBED_barrier_init()} and
-@code{GNUNET_TESTBED_barrier_cancel()} are used by experiment drivers. All
-barriers should be initialised by the experiment driver by calling
-@code{GNUNET_TESTBED_barrier_init()}. This function takes a name to
-identify the barrier, the quorum required for the barrier to be crossed
-and a notification callback for notifying the experiment driver when the
-barrier is crossed. @code{GNUNET_TESTBED_barrier_cancel()} cancels an
-initialised barrier and frees the resources allocated for it. This
-function can be called upon a initialised barrier before it is crossed.
-The remaining two functions @code{GNUNET_TESTBED_barrier_wait()} and
-@code{GNUNET_TESTBED_barrier_wait_cancel()} are used in the peer's
-processes. @code{GNUNET_TESTBED_barrier_wait()} connects to the local
-barrier service running on the same host the peer is running on and
-registers that the caller has reached the barrier and is waiting for the
-barrier to be crossed. Note that this function can only be used by peers
-which are started by testbed as this function tries to access the local
-barrier service which is part of the testbed controller service. Calling
-@code{GNUNET_TESTBED_barrier_wait()} on an uninitialised barrier results
-in failure. @code{GNUNET_TESTBED_barrier_wait_cancel()} cancels the
-notification registered by @code{GNUNET_TESTBED_barrier_wait()}.
-@c ***********************************************************************
-@menu
-* Implementation::
-@end menu
-@node Implementation
-@subsubsection Implementation
-Since barriers involve coordination between experiment driver and peers,
-the barrier service in the testbed controller is split into two
-components. The first component responds to the message generated by the
-barrier API used by the experiment driver (functions
-@code{GNUNET_TESTBED_barrier_init()} and
-@code{GNUNET_TESTBED_barrier_cancel()}) and the second component to the
-messages generated by barrier API used by peers (functions
-@code{GNUNET_TESTBED_barrier_wait()} and
-@code{GNUNET_TESTBED_barrier_wait_cancel()}).
-Calling @code{GNUNET_TESTBED_barrier_init()} sends a
-@code{GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_INIT} message to the master
-controller. The master controller then registers a barrier and calls
-@code{GNUNET_TESTBED_barrier_init()} for each its subcontrollers. In this
-way barrier initialisation is propagated to the controller hierarchy.
-While propagating initialisation, any errors at a subcontroller such as
-timeout during further propagation are reported up the hierarchy back to
-the experiment driver.
-Similar to @code{GNUNET_TESTBED_barrier_init()},
-@code{GNUNET_TESTBED_barrier_cancel()} propagates
-@code{GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_CANCEL} message which causes
-controllers to remove an initialised barrier.
-The second component is implemented as a separate service in the binary
-`gnunet-service-testbed' which already has the testbed controller service.
-Although this deviates from the gnunet process architecture of having one
-service per binary, it is needed in this case as this component needs
-access to barrier data created by the first component. This component
-responds to @code{GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_WAIT} messages from
-local peers when they call @code{GNUNET_TESTBED_barrier_wait()}. Upon
-receiving @code{GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_WAIT} message, the
-service checks if the requested barrier has been initialised before and
-if it was not initialised, an error status is sent through
-@code{GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_STATUS} message to the local
-peer and the connection from the peer is terminated. If the barrier is
-initialised before, the barrier's counter for reached peers is incremented
-and a notification is registered to notify the peer when the barrier is
-reached. The connection from the peer is left open.
-When enough peers required to attain the quorum send
-@code{GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_WAIT} messages, the controller
-sends a @code{GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_STATUS} message to its
-parent informing that the barrier is crossed. If the controller has
-started further subcontrollers, it delays this message until it receives
-a similar notification from each of those subcontrollers. Finally, the
-barriers API at the experiment driver receives the
-@code{GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_STATUS} when the barrier is
-reached at all the controllers.
-The barriers API at the experiment driver responds to the
-@code{GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_STATUS} message by echoing it
-back to the master controller and notifying the experiment controller
-through the notification callback that a barrier has been crossed. The
-echoed @code{GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_STATUS} message is
-propagated by the master controller to the controller hierarchy. This
-propagation triggers the notifications registered by peers at each of the
-controllers in the hierarchy. Note the difference between this downward
-propagation of the @code{GNUNET_MESSAGE_TYPE_TESTBED_BARRIER_STATUS}
-message from its upward propagation --- the upward propagation is needed
-for ensuring that the barrier is reached by all the controllers and the
-downward propagation is for triggering that the barrier is crossed.
-@cindex TESTBED Caveats
-@node TESTBED Caveats
-@subsection TESTBED Caveats
-This section documents a few caveats when using the GNUnet testbed
-subsystem.
-@c ***********************************************************************
-@menu
-* CORE must be started::
-* ATS must want the connections::
-@end menu
-@node CORE must be started
-@subsubsection CORE must be started
-A uncomplicated issue is bug #3993
-(@uref{https://bugs.gnunet.org/view.php?id=3993, https://bugs.gnunet.org/view.php?id=3993}):
-Your configuration MUST somehow ensure that for each peer the
-@code{CORE} service is started when the peer is setup, otherwise
-@code{TESTBED} may fail to connect peers when the topology is initialized,
-as @code{TESTBED} will start some @code{CORE} services but not
-necessarily all (but it relies on all of them running). The easiest way
-is to set
-@example
-[core]
-IMMEDIATE_START = YES
-@end example
-@noindent
-in the configuration file.
-Alternatively, having any service that directly or indirectly depends on
-@code{CORE} being started with @code{IMMEDIATE_START} will also do.
-This issue largely arises if users try to over-optimize by not
-starting any services with @code{IMMEDIATE_START}.
-@c ***********************************************************************
-@node ATS must want the connections
-@subsubsection ATS must want the connections
-When TESTBED sets up connections, it only offers the respective HELLO
-information to the TRANSPORT service. It is then up to the ATS service to
-@strong{decide} to use the connection. The ATS service will typically
-eagerly establish any connection if the number of total connections is
-low (relative to bandwidth). Details may further depend on the
-specific ATS backend that was configured. If ATS decides to NOT establish
-a connection (even though TESTBED provided the required information), then
-that connection will count as failed for TESTBED. Note that you can
-configure TESTBED to tolerate a certain number of connection failures
-(see '-e' option of gnunet-testbed-profiler). This issue largely arises
-for dense overlay topologies, especially if you try to create cliques
-with more than 20 peers.
-@cindex libgnunetutil
-@node libgnunetutil
-@section libgnunetutil
-libgnunetutil is the fundamental library that all GNUnet code builds upon.
-Ideally, this library should contain most of the platform dependent code
-(except for user interfaces and really special needs that only few
-applications have). It is also supposed to offer basic services that most
-if not all GNUnet binaries require. The code of libgnunetutil is in the
-@file{src/util/} directory. The public interface to the library is in the
-gnunet_util.h header. The functions provided by libgnunetutil fall
-roughly into the following categories (in roughly the order of importance
-for new developers):
-@itemize @bullet
-@item logging (common_logging.c)
-@item memory allocation (common_allocation.c)
-@item endianness conversion (common_endian.c)
-@item internationalization (common_gettext.c)
-@item String manipulation (string.c)
-@item file access (disk.c)
-@item buffered disk IO (bio.c)
-@item time manipulation (time.c)
-@item configuration parsing (configuration.c)
-@item command-line handling (getopt*.c)
-@item cryptography (crypto_*.c)
-@item data structures (container_*.c)
-@item CPS-style scheduling (scheduler.c)
-@item Program initialization (program.c)
-@item Networking (network.c, client.c, server*.c, service.c)
-@item message queuing (mq.c)
-@item bandwidth calculations (bandwidth.c)
-@item Other OS-related (os*.c, plugin.c, signal.c)
-@item Pseudonym management (pseudonym.c)
-@end itemize
-It should be noted that only developers that fully understand this entire
-API will be able to write good GNUnet code.
-Ideally, porting GNUnet should only require porting the gnunetutil
-library. More testcases for the gnunetutil APIs are therefore a great
-way to make porting of GNUnet easier.
-@menu
-* Logging::
-* Interprocess communication API (IPC)::
-* Cryptography API::
-* Message Queue API::
-* Service API::
-* Optimizing Memory Consumption of GNUnet's (Multi-) Hash Maps::
-* CONTAINER_MDLL API::
-@end menu
-@cindex Logging
-@cindex log levels
-@node Logging
-@subsection Logging
-GNUnet is able to log its activity, mostly for the purposes of debugging
-the program at various levels.
-@file{gnunet_common.h} defines several @strong{log levels}:
-@table @asis
-@item ERROR for errors
-(really problematic situations, often leading to crashes)
-@item WARNING for warnings
-(troubling situations that might have negative consequences, although
-not fatal)
-@item INFO for various information.
-Used somewhat rarely, as GNUnet statistics is used to hold and display
-most of the information that users might find interesting.
-@item DEBUG for debugging.
-Does not produce much output on normal builds, but when extra logging is
-enabled at compile time, a staggering amount of data is outputted under
-this log level.
-@end table
-Normal builds of GNUnet (configured with @code{--enable-logging[=yes]})
-are supposed to log nothing under DEBUG level. The
-@code{--enable-logging=verbose} configure option can be used to create a
-build with all logging enabled. However, such build will produce large
-amounts of log data, which is inconvenient when one tries to hunt down a
-specific problem.
-To mitigate this problem, GNUnet provides facilities to apply a filter to
-reduce the logs:
-@table @asis
-@item Logging by default When no log levels are configured in any other
-way (see below), GNUnet will default to the WARNING log level. This
-mostly applies to GNUnet command line utilities, services and daemons;
-tests will always set log level to WARNING or, if
-@code{--enable-logging=verbose} was passed to configure, to DEBUG. The
-default level is suggested for normal operation.
-@item The -L option Most GNUnet executables accept an "-L loglevel" or
-"--log=loglevel" option. If used, it makes the process set a global log
-level to "loglevel". Thus it is possible to run some processes
-with -L DEBUG, for example, and others with -L ERROR to enable specific
-settings to diagnose problems with a particular process.
-@item Configuration files.  Because GNUnet
-service and daemon processes are usually launched by gnunet-arm, it is not
-possible to pass different custom command line options directly to every
-one of them. The options passed to @code{gnunet-arm} only affect
-gnunet-arm and not the rest of GNUnet. However, one can specify a
-configuration key "OPTIONS" in the section that corresponds to a service
-or a daemon, and put a value of "-L loglevel" there. This will make the
-respective service or daemon set its log level to "loglevel" (as the
-value of OPTIONS will be passed as a command-line argument).
-To specify the same log level for all services without creating separate
-"OPTIONS" entries in the configuration for each one, the user can specify
-a config key "GLOBAL_POSTFIX" in the [arm] section of the configuration
-file. The value of GLOBAL_POSTFIX will be appended to all command lines
-used by the ARM service to run other services. It can contain any option
-valid for all GNUnet commands, thus in particular the "-L loglevel"
-option. The ARM service itself is, however, unaffected by GLOBAL_POSTFIX;
-to set log level for it, one has to specify "OPTIONS" key in the [arm]
-section.
-@item Environment variables.
-Setting global per-process log levels with "-L loglevel" does not offer
-sufficient log filtering granularity, as one service will call interface
-libraries and supporting libraries of other GNUnet services, potentially
-producing lots of debug log messages from these libraries. Also, changing
-the config file is not always convenient (especially when running the
-GNUnet test suite).@ To fix that, and to allow GNUnet to use different
-log filtering at runtime without re-compiling the whole source tree, the
-log calls were changed to be configurable at run time. To configure them
-one has to define environment variables "GNUNET_FORCE_LOGFILE",
-"GNUNET_LOG" and/or "GNUNET_FORCE_LOG":
-@itemize @bullet
-@item "GNUNET_LOG" only affects the logging when no global log level is
-configured by any other means (that is, the process does not explicitly
-set its own log level, there are no "-L loglevel" options on command line
-or in configuration files), and can be used to override the default
-WARNING log level.
-@item "GNUNET_FORCE_LOG" will completely override any other log
-configuration options given.
-@item "GNUNET_FORCE_LOGFILE" will completely override the location of the
-file to log messages to. It should contain a relative or absolute file
-name. Setting GNUNET_FORCE_LOGFILE is equivalent to passing
-"--log-file=logfile" or "-l logfile" option (see below). It supports "[]"
-format in file names, but not "@{@}" (see below).
-@end itemize
-Because environment variables are inherited by child processes when they
-are launched, starting or re-starting the ARM service with these
-variables will propagate them to all other services.
-"GNUNET_LOG" and "GNUNET_FORCE_LOG" variables must contain a specially
-formatted @strong{logging definition} string, which looks like this:@
-@c FIXME: Can we close this with [/component] instead?
-@example
-[component];[file];[function];[from_line[-to_line]];loglevel[/component...]
-@end example
-That is, a logging definition consists of definition entries, separated by
-slashes ('/'). If only one entry is present, there is no need to add a
-slash to its end (although it is not forbidden either).@ All definition
-fields (component, file, function, lines and loglevel) are mandatory, but
-(except for the loglevel) they can be empty. An empty field means
-"match anything". Note that even if fields are empty, the semicolon (';')
-separators must be present.@ The loglevel field is mandatory, and must
-contain one of the log level names (ERROR, WARNING, INFO or DEBUG).@
-The lines field might contain one non-negative number, in which case it
-matches only one line, or a range "from_line-to_line", in which case it
-matches any line in the interval [from_line;to_line] (that is, including
-both start and end line).@ GNUnet mostly defaults component name to the
-name of the service that is implemented in a process ('transport',
-'core', 'peerinfo', etc), but logging calls can specify custom component
-names using @code{GNUNET_log_from}.@ File name and function name are
-provided by the compiler (__FILE__ and __FUNCTION__ built-ins).
-Component, file and function fields are interpreted as non-extended
-regular expressions (GNU libc regex functions are used). Matching is
-case-sensitive, "^" and "$" will match the beginning and the end of the
-text. If a field is empty, its contents are automatically replaced with
-a ".*" regular expression, which matches anything. Matching is done in
-the default way, which means that the expression matches as long as it's
-contained anywhere in the string. Thus "GNUNET_" will match both
-"GNUNET_foo" and "BAR_GNUNET_BAZ". Use '^' and/or '$' to make sure that
-the expression matches at the start and/or at the end of the string.
-The semicolon (';') can't be escaped, and GNUnet will not use it in
-component names (it can't be used in function names and file names
-anyway).
-@end table
-Every logging call in GNUnet code will be (at run time) matched against
-the log definitions passed to the process. If a log definition fields are
-matching the call arguments, then the call log level is compared to the
-log level of that definition. If the call log level is less or equal to
-the definition log level, the call is allowed to proceed. Otherwise the
-logging call is forbidden, and nothing is logged. If no definitions
-matched at all, GNUnet will use the global log level or (if a global log
-level is not specified) will default to WARNING (that is, it will allow
-the call to proceed, if its level is less or equal to the global log
-level or to WARNING).
-That is, definitions are evaluated from left to right, and the first
-matching definition is used to allow or deny the logging call. Thus it is
-advised to place narrow definitions at the beginning of the logdef
-string, and generic definitions - at the end.
-Whether a call is allowed or not is only decided the first time this
-particular call is made. The evaluation result is then cached, so that
-any attempts to make the same call later will be allowed or disallowed
-right away. Because of that runtime log level evaluation should not
-significantly affect the process performance.
-Log definition parsing is only done once, at the first call to
-@code{GNUNET_log_setup ()} made by the process (which is usually
-done soon after it starts).
-At the moment of writing there is no way to specify logging definitions
-from configuration files, only via environment variables.
-At the moment GNUnet will stop processing a log definition when it
-encounters an error in definition formatting or an error in regular
-expression syntax, and will not report the failure in any way.
-@c ***********************************************************************
-@menu
-* Examples::
-* Log files::
-* Updated behavior of GNUNET_log::
-@end menu
-@node Examples
-@subsubsection Examples
-@table @asis
-@item @code{GNUNET_FORCE_LOG=";;;;DEBUG" gnunet-arm -s} Start GNUnet
-process tree, running all processes with DEBUG level (one should be
-careful with it, as log files will grow at alarming rate!)
-@item @code{GNUNET_FORCE_LOG="core;;;;DEBUG" gnunet-arm -s} Start GNUnet
-process tree, running the core service under DEBUG level (everything else
-will use configured or default level).
-@item Start GNUnet process tree, allowing any logging calls from
-gnunet-service-transport_validation.c (everything else will use
-configured or default level).
-@example
-GNUNET_FORCE_LOG=";gnunet-service-transport_validation.c;;; DEBUG" \
-gnunet-arm -s
-@end example
-@item Start GNUnet process tree, allowing any logging calls from
-gnunet-gnunet-service-fs_push.c (everything else will use configured or
-default level).
-@example
-GNUNET_FORCE_LOG="fs;gnunet-service-fs_push.c;;;DEBUG" gnunet-arm -s
-@end example
-@item Start GNUnet process tree, allowing any logging calls from the
-GNUNET_NETWORK_socket_select function (everything else will use
-configured or default level).
-@example
-GNUNET_FORCE_LOG=";;GNUNET_NETWORK_socket_select;;DEBUG" gnunet-arm -s
-@end example
-@item Start GNUnet process tree, allowing any logging calls from the
-components that have "transport" in their names, and are made from
-function that have "send" in their names. Everything else will be allowed
-to be logged only if it has WARNING level.
-@example
-GNUNET_FORCE_LOG="transport.*;;.*send.*;;DEBUG/;;;;WARNING" gnunet-arm -s
-@end example
-@end table
-On Windows, one can use batch files to run GNUnet processes with special
-environment variables, without affecting the whole system. Such batch
-file will look like this:
-@example
-set GNUNET_FORCE_LOG=;;do_transmit;;DEBUG@ gnunet-arm -s
-@end example
-(note the absence of double quotes in the environment variable definition,
-as opposed to earlier examples, which use the shell).
-Another limitation, on Windows, GNUNET_FORCE_LOGFILE @strong{MUST} be set
-in order to GNUNET_FORCE_LOG to work.
-@cindex Log files
-@node Log files
-@subsubsection Log files
-GNUnet can be told to log everything into a file instead of stderr (which
-is the default) using the "--log-file=logfile" or "-l logfile" option.
-This option can also be passed via command line, or from the "OPTION" and
-"GLOBAL_POSTFIX" configuration keys (see above). The file name passed
-with this option is subject to GNUnet filename expansion. If specified in
-"GLOBAL_POSTFIX", it is also subject to ARM service filename expansion,
-in particular, it may contain "@{@}" (left and right curly brace)
-sequence, which will be replaced by ARM with the name of the service.
-This is used to keep logs from more than one service separate, while only
-specifying one template containing "@{@}" in GLOBAL_POSTFIX.
-As part of a secondary file name expansion, the first occurrence of "[]"
-sequence ("left square brace" followed by "right square brace") in the
-file name will be replaced with a process identifier or the process when
-it initializes its logging subsystem. As a result, all processes will log
-into different files. This is convenient for isolating messages of a
-particular process, and prevents I/O races when multiple processes try to
-write into the file at the same time. This expansion is done
-independently of "@{@}" expansion that ARM service does (see above).
-The log file name that is specified via "-l" can contain format characters
-from the 'strftime' function family. For example, "%Y" will be replaced
-with the current year. Using "basename-%Y-%m-%d.log" would include the
-current year, month and day in the log file. If a GNUnet process runs for
-long enough to need more than one log file, it will eventually clean up
-old log files. Currently, only the last three log files (plus the current
-log file) are preserved. So once the fifth log file goes into use (so
-after 4 days if you use "%Y-%m-%d" as above), the first log file will be
-automatically deleted. Note that if your log file name only contains "%Y",
-then log files would be kept for 4 years and the logs from the first year
-would be deleted once year 5 begins. If you do not use any date-related
-string format codes, logs would never be automatically deleted by GNUnet.
-@c ***********************************************************************
-@node Updated behavior of GNUNET_log
-@subsubsection Updated behavior of GNUNET_log
-It's currently quite common to see constructions like this all over the
-code:
-@example
-#if MESH_DEBUG
-GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "MESH: client disconnected\n");
-#endif
-@end example
-The reason for the #if is not to avoid displaying the message when
-disabled (GNUNET_ERROR_TYPE takes care of that), but to avoid the
-compiler including it in the binary at all, when compiling GNUnet for
-platforms with restricted storage space / memory (MIPS routers,
-ARM plug computers / dev boards, etc).
-This presents several problems: the code gets ugly, hard to write and it
-is very easy to forget to include the #if guards, creating non-consistent
-code. A new change in GNUNET_log aims to solve these problems.
-@strong{This change requires to @file{./configure} with at least
-@code{--enable-logging=verbose} to see debug messages.}
-Here is an example of code with dense debug statements:
-@example
-switch (restrict_topology) @{
-case GNUNET_TESTING_TOPOLOGY_CLIQUE:#if VERBOSE_TESTING
-GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, _("Blacklisting all but clique
-topology\n")); #endif unblacklisted_connections = create_clique (pg,
-&remove_connections, BLACKLIST, GNUNET_NO); break; case
-GNUNET_TESTING_TOPOLOGY_SMALL_WORLD_RING: #if VERBOSE_TESTING GNUNET_log
-(GNUNET_ERROR_TYPE_DEBUG, _("Blacklisting all but small world (ring)
-topology\n")); #endif unblacklisted_connections = create_small_world_ring
-(pg,&remove_connections, BLACKLIST); break;
-@end example
-Pretty hard to follow, huh?
-From now on, it is not necessary to include the #if / #endif statements to
-achieve the same behavior. The @code{GNUNET_log} and @code{GNUNET_log_from}
-macros take care of it for you, depending on the configure option:
-@itemize @bullet
-@item If @code{--enable-logging} is set to @code{no}, the binary will
-contain no log messages at all.
-@item If @code{--enable-logging} is set to @code{yes}, the binary will
-contain no DEBUG messages, and therefore running with @command{-L DEBUG}
-will have
-no effect. Other messages (ERROR, WARNING, INFO, etc) will be included.
-@item If @code{--enable-logging} is set to @code{verbose}, or
-@code{veryverbose} the binary will contain DEBUG messages (still, it will
-be necessary to run with @command{-L DEBUG} or set the DEBUG config option
-to show them).
-@end itemize
-If you are a developer:
-@itemize @bullet
-@item please make sure that you @code{./configure
--enable-logging=@{verbose,veryverbose@}}, so you can see DEBUG messages.
-@item please remove the @code{#if} statements around @code{GNUNET_log
-(GNUNET_ERROR_TYPE_DEBUG, ...)} lines, to improve the readability of your
-code.
-@end itemize
-Since now activating DEBUG automatically makes it VERBOSE and activates
-@strong{all} debug messages by default, you probably want to use the
-@uref{https://docs.gnunet.org/#Logging, https://docs.gnunet.org/#Logging}
-functionality to filter only relevant messages.
-A suitable configuration could be:
-@example
-$ export GNUNET_FORCE_LOG="^YOUR_SUBSYSTEM$;;;;DEBUG/;;;;WARNING"
-@end example
-Which will behave almost like enabling DEBUG in that subsystem before the
-change. Of course you can adapt it to your particular needs, this is only
-a quick example.
-@cindex Interprocess communication API
-@cindex ICP
-@node Interprocess communication API (IPC)
-@subsection Interprocess communication API (IPC)
-In GNUnet a variety of new message types might be defined and used in
-interprocess communication, in this tutorial we use the
-@code{struct AddressLookupMessage} as a example to introduce how to
-construct our own message type in GNUnet and how to implement the message
-communication between service and client.
-(Here, a client uses the @code{struct AddressLookupMessage} as a request
-to ask the server to return the address of any other peer connecting to
-the service.)
-@c ***********************************************************************
-@menu
-* Define new message types::
-* Define message struct::
-* Client - Establish connection::
-* Client - Initialize request message::
-* Client - Send request and receive response::
-* Server - Startup service::
-* Server - Add new handles for specified messages::
-* Server - Process request message::
-* Server - Response to client::
-* Server - Notification of clients::
-* Conversion between Network Byte Order (Big Endian) and Host Byte Order::
-@end menu
-@node Define new message types
-@subsubsection Define new message types
-First of all, you should define the new message type in
-@file{gnunet_protocols.h}:
-@example
- // Request to look addresses of peers in server.
-#define GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_LOOKUP 29
-  // Response to the address lookup request.
-#define GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_REPLY 30
-@end example
-@c ***********************************************************************
-@node Define message struct
-@subsubsection Define message struct
-After the type definition, the specified message structure should also be
-described in the header file, e.g. transport.h in our case.
-@example
-struct AddressLookupMessage @{
-  struct GNUNET_MessageHeader header;
-  int32_t numeric_only GNUNET_PACKED;
-  struct GNUNET_TIME_AbsoluteNBO timeout;
-  uint32_t addrlen GNUNET_PACKED;
-  /* followed by 'addrlen' bytes of the actual address, then
-     followed by the 0-terminated name of the transport */ @};
-GNUNET_NETWORK_STRUCT_END
-@end example
-Please note @code{GNUNET_NETWORK_STRUCT_BEGIN} and @code{GNUNET_PACKED}
-which both ensure correct alignment when sending structs over the network.
-@menu
-@end menu
-@c ***********************************************************************
-@node Client - Establish connection
-@subsubsection Client - Establish connection
-At first, on the client side, the underlying API is employed to create a
-new connection to a service, in our example the transport service would be
-connected.
-@example
-struct GNUNET_CLIENT_Connection *client;
-client = GNUNET_CLIENT_connect ("transport", cfg);
-@end example
-@c ***********************************************************************
-@node Client - Initialize request message
-@subsubsection Client - Initialize request message
-When the connection is ready, we initialize the message. In this step,
-all the fields of the message should be properly initialized, namely the
-size, type, and some extra user-defined data, such as timeout, name of
-transport, address and name of transport.
-@example
-struct AddressLookupMessage *msg;
-size_t len = sizeof (struct AddressLookupMessage)
-  + addressLen
-  + strlen (nameTrans)
-  + 1;
-msg->header->size = htons (len);
-msg->header->type = htons
-(GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_LOOKUP);
-msg->timeout = GNUNET_TIME_absolute_hton (abs_timeout);
-msg->addrlen = htonl (addressLen);
-char *addrbuf = (char *) &msg[1];
-memcpy (addrbuf, address, addressLen);
-char *tbuf = &addrbuf[addressLen];
-memcpy (tbuf, nameTrans, strlen (nameTrans) + 1);
-@end example
-Note that, here the functions @code{htonl}, @code{htons} and
-@code{GNUNET_TIME_absolute_hton} are applied to convert little endian
-into big endian, about the usage of the big/small endian order and the
-corresponding conversion function please refer to Introduction of
-Big Endian and Little Endian.
-@c ***********************************************************************
-@node Client - Send request and receive response
-@subsubsection Client - Send request and receive response
-@b{FIXME: This is very outdated, see the tutorial for the current API!}
-Next, the client would send the constructed message as a request to the
-service and wait for the response from the service. To accomplish this
-goal, there are a number of API calls that can be used. In this example,
-@code{GNUNET_CLIENT_transmit_and_get_response} is chosen as the most
-appropriate function to use.
-@example
-GNUNET_CLIENT_transmit_and_get_response
-(client, msg->header, timeout, GNUNET_YES, &address_response_processor,
-arp_ctx);
-@end example
-the argument @code{address_response_processor} is a function with
-@code{GNUNET_CLIENT_MessageHandler} type, which is used to process the
-reply message from the service.
-@node Server - Startup service
-@subsubsection Server - Startup service
-After receiving the request message, we run a standard GNUnet service
-startup sequence using @code{GNUNET_SERVICE_run}, as follows,
-@example
-int main(int argc, char**argv) @{
-  GNUNET_SERVICE_run(argc, argv, "transport"
-  GNUNET_SERVICE_OPTION_NONE, &run, NULL)); @}
-@end example
-@c ***********************************************************************
-@node Server - Add new handles for specified messages
-@subsubsection Server - Add new handles for specified messages
-in the function above the argument @code{run} is used to initiate
-transport service,and defined like this:
-@example
-static void run (void *cls,
-struct GNUNET_SERVER_Handle *serv,
-const struct GNUNET_CONFIGURATION_Handle *cfg) @{
-  GNUNET_SERVER_add_handlers (serv, handlers); @}
-@end example
-Here, @code{GNUNET_SERVER_add_handlers} must be called in the run
-function to add new handlers in the service. The parameter
-@code{handlers} is a list of @code{struct GNUNET_SERVER_MessageHandler}
-to tell the service which function should be called when a particular
-type of message is received, and should be defined in this way:
-@example
-static struct GNUNET_SERVER_MessageHandler handlers[] = @{
-  @{&handle_start,
-   NULL,
-   GNUNET_MESSAGE_TYPE_TRANSPORT_START,
-   0@},
-  @{&handle_send,
-   NULL,
-   GNUNET_MESSAGE_TYPE_TRANSPORT_SEND,
-   0@},
-  @{&handle_try_connect,
-   NULL,
-   GNUNET_MESSAGE_TYPE_TRANSPORT_TRY_CONNECT,
-   sizeof (struct TryConnectMessage)
-  @},
-  @{&handle_address_lookup,
-   NULL,
-   GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_LOOKUP,
-   0@},
-  @{NULL,
-   NULL,
-   0,
-   0@}
-@};
-@end example
-As shown, the first member of the struct in the first area is a callback
-function, which is called to process the specified message types, given
-as the third member. The second parameter is the closure for the callback
-function, which is set to @code{NULL} in most cases, and the last
-parameter is the expected size of the message of this type, usually we
-set it to 0 to accept variable size, for special cases the exact size of
-the specified message also can be set. In addition, the terminator sign
-depicted as @code{@{NULL, NULL, 0, 0@}} is set in the last area.
-@c ***********************************************************************
-@node Server - Process request message
-@subsubsection Server - Process request message
-After the initialization of transport service, the request message would
-be processed. Before handling the main message data, the validity of this
-message should be checked out, e.g., to check whether the size of message
-is correct.
-@example
-size = ntohs (message->size);
-if (size < sizeof (struct AddressLookupMessage)) @{
-  GNUNET_break_op (0);
-  GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
-  return; @}
-@end example
-Note that, opposite to the construction method of the request message in
-the client, in the server the function @code{nothl} and @code{ntohs}
-should be employed during the extraction of the data from the message, so
-that the data in big endian order can be converted back into little
-endian order. See more in detail please refer to Introduction of
-Big Endian and Little Endian.
-Moreover in this example, the name of the transport stored in the message
-is a 0-terminated string, so we should also check whether the name of the
-transport in the received message is 0-terminated:
-@example
-nameTransport = (const char *) &address[addressLen];
-if (nameTransport[size - sizeof
-                  (struct AddressLookupMessage)
-                  - addressLen - 1] != '\0') @{
-  GNUNET_break_op (0);
-  GNUNET_SERVER_receive_done (client,
-                              GNUNET_SYSERR);
-  return; @}
-@end example
-Here, @code{GNUNET_SERVER_receive_done} should be called to tell the
-service that the request is done and can receive the next message. The
-argument @code{GNUNET_SYSERR} here indicates that the service didn't
-understand the request message, and the processing of this request would
-be terminated.
-In comparison to the aforementioned situation, when the argument is equal
-to @code{GNUNET_OK}, the service would continue to process the request
-message.
-@c ***********************************************************************
-@node Server - Response to client
-@subsubsection Server - Response to client
-Once the processing of current request is done, the server should give the
-response to the client. A new @code{struct AddressLookupMessage} would be
-produced by the server in a similar way as the client did and sent to the
-client, but here the type should be
-@code{GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_REPLY} rather than
-@code{GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_LOOKUP} in client.
-@example
-struct AddressLookupMessage *msg;
-size_t len = sizeof (struct AddressLookupMessage)
-  + addressLen
-  + strlen (nameTrans) + 1;
-msg->header->size = htons (len);
-msg->header->type = htons
-  (GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_REPLY);
-// ...
-struct GNUNET_SERVER_TransmitContext *tc;
-tc = GNUNET_SERVER_transmit_context_create (client);
-GNUNET_SERVER_transmit_context_append_data
-(tc,
- NULL,
- 0,
- GNUNET_MESSAGE_TYPE_TRANSPORT_ADDRESS_REPLY);
-GNUNET_SERVER_transmit_context_run (tc, rtimeout);
-@end example
-Note that, there are also a number of other APIs provided to the service
-to send the message.
-@c ***********************************************************************
-@node Server - Notification of clients
-@subsubsection Server - Notification of clients
-Often a service needs to (repeatedly) transmit notifications to a client
-or a group of clients. In these cases, the client typically has once
-registered for a set of events and then needs to receive a message
-whenever such an event happens (until the client disconnects). The use of
-a notification context can help manage message queues to clients and
-handle disconnects. Notification contexts can be used to send
-individualized messages to a particular client or to broadcast messages
-to a group of clients. An individualized notification might look like
-this:
-@example
-GNUNET_SERVER_notification_context_unicast(nc,
-                                           client,
-                                           msg,
-                                           GNUNET_YES);
-@end example
-Note that after processing the original registration message for
-notifications, the server code still typically needs to call
-@code{GNUNET_SERVER_receive_done} so that the client can transmit further
-messages to the server.
-@c ***********************************************************************
-@node Conversion between Network Byte Order (Big Endian) and Host Byte Order
-@subsubsection Conversion between Network Byte Order (Big Endian) and Host Byte Order
-@c %** subsub? it's a referenced page on the ipc document.
-Here we can simply comprehend big endian and little endian as Network Byte
-Order and Host Byte Order respectively. What is the difference between
-both two?
-Usually in our host computer we store the data byte as Host Byte Order,
-for example, we store a integer in the RAM which might occupies 4 Byte,
-as Host Byte Order the higher Byte would be stored at the lower address
-of RAM, and the lower Byte would be stored at the higher address of RAM.
-However, contrast to this, Network Byte Order just take the totally
-opposite way to store the data, says, it will store the lower Byte at the
-lower address, and the higher Byte will stay at higher address.
-For the current communication of network, we normally exchange the
-information by surveying the data package, every two host wants to
-communicate with each other must send and receive data package through
-network. In order to maintain the identity of data through the
-transmission in the network, the order of the Byte storage must changed
-before sending and after receiving the data.
-There ten convenient functions to realize the conversion of Byte Order in
-GNUnet, as following:
-@table @asis
-@item uint16_t htons(uint16_t hostshort) Convert host byte order to net
-byte order with short int
-@item uint32_t htonl(uint32_t hostlong) Convert host byte
-order to net byte order with long int
-@item uint16_t ntohs(uint16_t netshort)
-Convert net byte order to host byte order with short int
-@item uint32_t
-ntohl(uint32_t netlong) Convert net byte order to host byte order with
-long int
-@item unsigned long long GNUNET_ntohll (unsigned long long netlonglong)
-Convert net byte order to host byte order with long long int
-@item unsigned long long GNUNET_htonll (unsigned long long hostlonglong)
-Convert host byte order to net byte order with long long int
-@item struct GNUNET_TIME_RelativeNBO GNUNET_TIME_relative_hton
-(struct GNUNET_TIME_Relative a) Convert relative time to network byte
-order.
-@item struct GNUNET_TIME_Relative GNUNET_TIME_relative_ntoh
-(struct GNUNET_TIME_RelativeNBO a) Convert relative time from network
-byte order.
-@item struct GNUNET_TIME_AbsoluteNBO GNUNET_TIME_absolute_hton
-(struct GNUNET_TIME_Absolute a) Convert relative time to network byte
-order.
-@item struct GNUNET_TIME_Absolute GNUNET_TIME_absolute_ntoh
-(struct GNUNET_TIME_AbsoluteNBO a) Convert relative time from network
-byte order.
-@end table
-@cindex Cryptography API
-@node Cryptography API
-@subsection Cryptography API
-The gnunetutil APIs provides the cryptographic primitives used in GNUnet.
-GNUnet uses 2048 bit RSA keys for the session key exchange and for signing
-messages by peers and most other public-key operations. Most researchers
-in cryptography consider 2048 bit RSA keys as secure and practically
-unbreakable for a long time. The API provides functions to create a fresh
-key pair, read a private key from a file (or create a new file if the
-file does not exist), encrypt, decrypt, sign, verify and extraction of
-the public key into a format suitable for network transmission.
-For the encryption of files and the actual data exchanged between peers
-GNUnet uses 256-bit AES encryption. Fresh, session keys are negotiated
-for every new connection.@ Again, there is no published technique to
-break this cipher in any realistic amount of time. The API provides
-functions for generation of keys, validation of keys (important for
-checking that decryptions using RSA succeeded), encryption and decryption.
-GNUnet uses SHA-512 for computing one-way hash codes. The API provides
-functions to compute a hash over a block in memory or over a file on disk.
-The crypto API also provides functions for randomizing a block of memory,
-obtaining a single random number and for generating a permutation of the
-numbers 0 to n-1. Random number generation distinguishes between WEAK and
-STRONG random number quality; WEAK random numbers are pseudo-random
-whereas STRONG random numbers use entropy gathered from the operating
-system.
-Finally, the crypto API provides a means to deterministically generate a
-1024-bit RSA key from a hash code. These functions should most likely not
-be used by most applications; most importantly,
-GNUNET_CRYPTO_rsa_key_create_from_hash does not create an RSA-key that
-should be considered secure for traditional applications of RSA.
-@cindex Message Queue API
-@node Message Queue API
-@subsection Message Queue API
-@strong{ Introduction }@
-Often, applications need to queue messages that
-are to be sent to other GNUnet peers, clients or services. As all of
-GNUnet's message-based communication APIs, by design, do not allow
-messages to be queued, it is common to implement custom message queues
-manually when they are needed. However, writing very similar code in
-multiple places is tedious and leads to code duplication.
-MQ (for Message Queue) is an API that provides the functionality to
-implement and use message queues. We intend to eventually replace all of
-the custom message queue implementations in GNUnet with MQ.
-@strong{ Basic Concepts }@
-The two most important entities in MQ are queues and envelopes.
-Every queue is backed by a specific implementation (e.g. for mesh, stream,
-connection, server client, etc.) that will actually deliver the queued
-messages. For convenience,@ some queues also allow to specify a list of
-message handlers. The message queue will then also wait for incoming
-messages and dispatch them appropriately.
-An envelope holds the memory for a message, as well as metadata
-(Where is the envelope queued? What should happen after it has been
-sent?). Any envelope can only be queued in one message queue.
-@strong{ Creating Queues }@
-The following is a list of currently available message queues. Note that
-to avoid layering issues, message queues for higher level APIs are not
-part of @code{libgnunetutil}, but@ the respective API itself provides the
-queue implementation.
-@table @asis
-@item @code{GNUNET_MQ_queue_for_connection_client}
-Transmits queued messages over a @code{GNUNET_CLIENT_Connection} handle.
-Also supports receiving with message handlers.
-@item @code{GNUNET_MQ_queue_for_server_client}
-Transmits queued messages over a @code{GNUNET_SERVER_Client} handle. Does
-not support incoming message handlers.
-@item @code{GNUNET_MESH_mq_create} Transmits queued messages over a
-@code{GNUNET_MESH_Tunnel} handle. Does not support incoming message
-handlers.
-@item @code{GNUNET_MQ_queue_for_callbacks} This is the most general
-implementation. Instead of delivering and receiving messages with one of
-GNUnet's communication APIs, implementation callbacks are called. Refer to
-"Implementing Queues" for a more detailed explanation.
-@end table
-@strong{ Allocating Envelopes }@
-A GNUnet message (as defined by the GNUNET_MessageHeader) has three
-parts: The size, the type, and the body.
-MQ provides macros to allocate an envelope containing a message
-conveniently, automatically setting the size and type fields of the
-message.
-Consider the following simple message, with the body consisting of a
-single number value.
-@c why the empty code function?
-@code{}
-@example
-struct NumberMessage @{
-  /** Type: GNUNET_MESSAGE_TYPE_EXAMPLE_1 */
-  struct GNUNET_MessageHeader header;
-  uint32_t number GNUNET_PACKED;
-@};
-@end example
-An envelope containing an instance of the NumberMessage can be
-constructed like this:
-@example
-struct GNUNET_MQ_Envelope *ev;
-struct NumberMessage *msg;
-ev = GNUNET_MQ_msg (msg, GNUNET_MESSAGE_TYPE_EXAMPLE_1);
-msg->number = htonl (42);
-@end example
-In the above code, @code{GNUNET_MQ_msg} is a macro. The return value is
-the newly allocated envelope. The first argument must be a pointer to some
-@code{struct} containing a @code{struct GNUNET_MessageHeader header}
-field, while the second argument is the desired message type, in host
-byte order.
-The @code{msg} pointer now points to an allocated message, where the
-message type and the message size are already set. The message's size is
-inferred from the type of the @code{msg} pointer: It will be set to
-'sizeof(*msg)', properly converted to network byte order.
-If the message body's size is dynamic, then the macro
-@code{GNUNET_MQ_msg_extra} can be used to allocate an envelope whose
-message has additional space allocated after the @code{msg} structure.
-If no structure has been defined for the message,
-@code{GNUNET_MQ_msg_header_extra} can be used to allocate additional space
-after the message header. The first argument then must be a pointer to a
-@code{GNUNET_MessageHeader}.
-@strong{Envelope Properties}@
-A few functions in MQ allow to set additional properties on envelopes:
-@table @asis
-@item @code{GNUNET_MQ_notify_sent} Allows to specify a function that will
-be called once the envelope's message has been sent irrevocably.
-An envelope can be canceled precisely up to the@ point where the notify
-sent callback has been called.
-@item @code{GNUNET_MQ_disable_corking} No corking will be used when
-sending the message. Not every@ queue supports this flag, per default,
-envelopes are sent with corking.@
-@end table
-@strong{Sending Envelopes}@
-Once an envelope has been constructed, it can be queued for sending with
-@code{GNUNET_MQ_send}.
-Note that in order to avoid memory leaks, an envelope must either be sent
-(the queue will free it) or destroyed explicitly with
-@code{GNUNET_MQ_discard}.
-@strong{Canceling Envelopes}@
-An envelope queued with @code{GNUNET_MQ_send} can be canceled with
-@code{GNUNET_MQ_cancel}. Note that after the notify sent callback has
-been called, canceling a message results in undefined behavior.
-Thus it is unsafe to cancel an envelope that does not have a notify sent
-callback. When canceling an envelope, it is not necessary@ to call
-@code{GNUNET_MQ_discard}, and the envelope can't be sent again.
-@strong{ Implementing Queues }@
-@code{TODO}
-@cindex Service API
-@node Service API
-@subsection Service API
-Most GNUnet code lives in the form of services. Services are processes
-that offer an API for other components of the system to build on. Those
-other components can be command-line tools for users, graphical user
-interfaces or other services. Services provide their API using an IPC
-protocol. For this, each service must listen on either a TCP port or a
-UNIX domain socket; for this, the service implementation uses the server
-API. This use of server is exposed directly to the users of the service
-API. Thus, when using the service API, one is usually also often using
-large parts of the server API. The service API provides various
-convenience functions, such as parsing command-line arguments and the
-configuration file, which are not found in the server API.
-The dual to the service/server API is the client API, which can be used to
-access services.
-The most common way to start a service is to use the
-@code{GNUNET_SERVICE_run} function from the program's main function.
-@code{GNUNET_SERVICE_run} will then parse the command line and
-configuration files and, based on the options found there,
-start the server. It will then give back control to the main
-program, passing the server and the configuration to the
-@code{GNUNET_SERVICE_Main} callback. @code{GNUNET_SERVICE_run}
-will also take care of starting the scheduler loop.
-If this is inappropriate (for example, because the scheduler loop
-is already running), @code{GNUNET_SERVICE_start} and
-related functions provide an alternative to @code{GNUNET_SERVICE_run}.
-When starting a service, the service_name option is used to determine
-which sections in the configuration file should be used to configure the
-service. A typical value here is the name of the @file{src/}
-sub-directory, for example @file{statistics}.
-The same string would also be given to
-@code{GNUNET_CLIENT_connect} to access the service.
-Once a service has been initialized, the program should use the
-@code{GNUNET_SERVICE_Main} callback to register message handlers
-using @code{GNUNET_SERVER_add_handlers}.
-The service will already have registered a handler for the
-"TEST" message.
-@findex GNUNET_SERVICE_Options
-The option bitfield (@code{enum GNUNET_SERVICE_Options})
-determines how a service should behave during shutdown.
-There are three key strategies:
-@table @asis
-@item instant (@code{GNUNET_SERVICE_OPTION_NONE})
-Upon receiving the shutdown
-signal from the scheduler, the service immediately terminates the server,
-closing all existing connections with clients.
-@item manual (@code{GNUNET_SERVICE_OPTION_MANUAL_SHUTDOWN})
-The service does nothing by itself
-during shutdown. The main program will need to take the appropriate
-action by calling GNUNET_SERVER_destroy or GNUNET_SERVICE_stop (depending
-on how the service was initialized) to terminate the service. This method
-is used by gnunet-service-arm and rather uncommon.
-@item soft (@code{GNUNET_SERVICE_OPTION_SOFT_SHUTDOWN})
-Upon receiving the shutdown signal from the scheduler,
-the service immediately tells the server to stop
-listening for incoming clients. Requests from normal existing clients are
-still processed and the server/service terminates once all normal clients
-have disconnected. Clients that are not expected to ever disconnect (such
-as clients that monitor performance values) can be marked as 'monitor'
-clients using GNUNET_SERVER_client_mark_monitor. Those clients will
-continue to be processed until all 'normal' clients have disconnected.
-Then, the server will terminate, closing the monitor connections.
-This mode is for example used by 'statistics', allowing existing 'normal'
-clients to set (possibly persistent) statistic values before terminating.
-@end table
-@c ***********************************************************************
-@node Optimizing Memory Consumption of GNUnet's (Multi-) Hash Maps
-@subsection Optimizing Memory Consumption of GNUnet's (Multi-) Hash Maps
-A commonly used data structure in GNUnet is a (multi-)hash map. It is most
-often used to map a peer identity to some data structure, but also to map
-arbitrary keys to values (for example to track requests in the distributed
-hash table or in file-sharing). As it is commonly used, the DHT is
-actually sometimes responsible for a large share of GNUnet's overall
-memory consumption (for some processes, 30% is not uncommon). The
-following text documents some API quirks (and their implications for
-applications) that were recently introduced to minimize the footprint of
-the hash map.
-@c ***********************************************************************
-@menu
-* Analysis::
-* Solution::
-* Migration::
-* Conclusion::
-* Availability::
-@end menu
-@node Analysis
-@subsubsection Analysis
-The main reason for the "excessive" memory consumption by the hash map is
-that GNUnet uses 512-bit cryptographic hash codes --- and the
-(multi-)hash map also uses the same 512-bit 'struct GNUNET_HashCode'. As
-a result, storing just the keys requires 64 bytes of memory for each key.
-As some applications like to keep a large number of entries in the hash
-map (after all, that's what maps are good for), 64 bytes per hash is
-significant: keeping a pointer to the value and having a linked list for
-collisions consume between 8 and 16 bytes, and 'malloc' may add about the
-same overhead per allocation, putting us in the 16 to 32 byte per entry
-ballpark. Adding a 64-byte key then triples the overall memory
-requirement for the hash map.
-To make things "worse", most of the time storing the key in the hash map
-is not required: it is typically already in memory elsewhere! In most
-cases, the values stored in the hash map are some application-specific
-struct that _also_ contains the hash. Here is a simplified example:
-@example
-struct MyValue @{
-struct GNUNET_HashCode key;
-unsigned int my_data; @};
-// ...
-val = GNUNET_malloc (sizeof (struct MyValue));
-val->key = key;
-val->my_data = 42;
-GNUNET_CONTAINER_multihashmap_put (map, &key, val, ...);
-@end example
-This is a common pattern as later the entries might need to be removed,
-and at that time it is convenient to have the key immediately at hand:
-@example
-GNUNET_CONTAINER_multihashmap_remove (map, &val->key, val);
-@end example
-Note that here we end up with two times 64 bytes for the key, plus maybe
-64 bytes total for the rest of the 'struct MyValue' and the map entry in
-the hash map. The resulting redundant storage of the key increases
-overall memory consumption per entry from the "optimal" 128 bytes to 192
-bytes. This is not just an extreme example: overheads in practice are
-actually sometimes close to those highlighted in this example. This is
-especially true for maps with a significant number of entries, as there
-we tend to really try to keep the entries small.
-@c ***********************************************************************
-@node Solution
-@subsubsection Solution
-The solution that has now been implemented is to @strong{optionally}
-allow the hash map to not make a (deep) copy of the hash but instead have
-a pointer to the hash/key in the entry. This reduces the memory
-consumption for the key from 64 bytes to 4 to 8 bytes. However, it can
-also only work if the key is actually stored in the entry (which is the
-case most of the time) and if the entry does not modify the key (which in
-all of the code I'm aware of has been always the case if there key is
-stored in the entry). Finally, when the client stores an entry in the
-hash map, it @strong{must} provide a pointer to the key within the entry,
-not just a pointer to a transient location of the key. If
-the client code does not meet these requirements, the result is a dangling
-pointer and undefined behavior of the (multi-)hash map API.
-@c ***********************************************************************
-@node Migration
-@subsubsection Migration
-To use the new feature, first check that the values contain the respective
-key (and never modify it). Then, all calls to
-@code{GNUNET_CONTAINER_multihashmap_put} on the respective map must be
-audited and most likely changed to pass a pointer into the value's struct.
-For the initial example, the new code would look like this:
-@example
-struct MyValue @{
-struct GNUNET_HashCode key;
-unsigned int my_data; @};
-// ...
-val = GNUNET_malloc (sizeof (struct MyValue));
-val->key = key; val->my_data = 42;
-GNUNET_CONTAINER_multihashmap_put (map, &val->key, val, ...);
-@end example
-Note that @code{&val} was changed to @code{&val->key} in the argument to
-the @code{put} call. This is critical as often @code{key} is on the stack
-or in some other transient data structure and thus having the hash map
-keep a pointer to @code{key} would not work. Only the key inside of
-@code{val} has the same lifetime as the entry in the map (this must of
-course be checked as well). Naturally, @code{val->key} must be
-initialized before the @code{put} call. Once all @code{put} calls have
-been converted and double-checked, you can change the call to create the
-hash map from
-@example
-map =
-GNUNET_CONTAINER_multihashmap_create (SIZE, GNUNET_NO);
-@end example
-to
-@example
-map = GNUNET_CONTAINER_multihashmap_create (SIZE, GNUNET_YES);
-@end example
-If everything was done correctly, you now use about 60 bytes less memory
-per entry in @code{map}. However, if now (or in the future) any call to
-@code{put} does not ensure that the given key is valid until the entry is
-removed from the map, undefined behavior is likely to be observed.
-@c ***********************************************************************
-@node Conclusion
-@subsubsection Conclusion
-The new optimization can is often applicable and can result in a
-reduction in memory consumption of up to 30% in practice. However, it
-makes the code less robust as additional invariants are imposed on the
-multi hash map client. Thus applications should refrain from enabling the
-new mode unless the resulting performance increase is deemed significant
-enough. In particular, it should generally not be used in new code (wait
-at least until benchmarks exist).
-@c ***********************************************************************
-@node Availability
-@subsubsection Availability
-The new multi hash map code was committed in SVN 24319 (which made its
-way into GNUnet version 0.9.4).
-Various subsystems (transport, core, dht, file-sharing) were
-previously audited and modified to take advantage of the new capability.
-In particular, memory consumption of the file-sharing service is expected
-to drop by 20-30% due to this change.
-@cindex CONTAINER_MDLL API
-@node CONTAINER_MDLL API
-@subsection CONTAINER_MDLL API
-This text documents the GNUNET_CONTAINER_MDLL API. The
-GNUNET_CONTAINER_MDLL API is similar to the GNUNET_CONTAINER_DLL API in
-that it provides operations for the construction and manipulation of
-doubly-linked lists. The key difference to the (simpler) DLL-API is that
-the MDLL-version allows a single element (instance of a "struct") to be
-in multiple linked lists at the same time.
-Like the DLL API, the MDLL API stores (most of) the data structures for
-the doubly-linked list with the respective elements; only the 'head' and
-'tail' pointers are stored "elsewhere" --- and the application needs to
-provide the locations of head and tail to each of the calls in the
-MDLL API. The key difference for the MDLL API is that the "next" and
-"previous" pointers in the struct can no longer be simply called "next"
-and "prev" --- after all, the element may be in multiple doubly-linked
-lists, so we cannot just have one "next" and one "prev" pointer!
-The solution is to have multiple fields that must have a name of the
-format "next_XX" and "prev_XX" where "XX" is the name of one of the
-doubly-linked lists. Here is a simple example:
-@example
-struct MyMultiListElement @{
-  struct MyMultiListElement *next_ALIST;
-  struct MyMultiListElement *prev_ALIST;
-  struct MyMultiListElement *next_BLIST;
-  struct MyMultiListElement *prev_BLIST;
-  void
-  *data;
-@};
-@end example
-Note that by convention, we use all-uppercase letters for the list names.
-In addition, the program needs to have a location for the head and tail
-pointers for both lists, for example:
-@example
-static struct MyMultiListElement *head_ALIST;
-static struct MyMultiListElement *tail_ALIST;
-static struct MyMultiListElement *head_BLIST;
-static struct MyMultiListElement *tail_BLIST;
-@end example
-Using the MDLL-macros, we can now insert an element into the ALIST:
-@example
-GNUNET_CONTAINER_MDLL_insert (ALIST, head_ALIST, tail_ALIST, element);
-@end example
-Passing "ALIST" as the first argument to MDLL specifies which of the
-next/prev fields in the 'struct MyMultiListElement' should be used. The
-extra "ALIST" argument and the "_ALIST" in the names of the
-next/prev-members are the only differences between the MDDL and DLL-API.
-Like the DLL-API, the MDLL-API offers functions for inserting (at head,
-at tail, after a given element) and removing elements from the list.
-Iterating over the list should be done by directly accessing the
-"next_XX" and/or "prev_XX" members.
-@cindex Automatic Restart Manager
-@cindex ARM
-@node Automatic Restart Manager (ARM)
-@section Automatic Restart Manager (ARM)
-GNUnet's Automated Restart Manager (ARM) is the GNUnet service responsible
-for system initialization and service babysitting. ARM starts and halts
-services, detects configuration changes and restarts services impacted by
-the changes as needed. It's also responsible for restarting services in
-case of crashes and is planned to incorporate automatic debugging for
-diagnosing service crashes providing developers insights about crash
-reasons. The purpose of this document is to give GNUnet developer an idea
-about how ARM works and how to interact with it.
-@menu
-* Basic functionality::
-* Key configuration options::
-* ARM - Availability::
-* Reliability::
-@end menu
-@c ***********************************************************************
-@node Basic functionality
-@subsection Basic functionality
-@itemize @bullet
-@item ARM source code can be found under "src/arm".@ Service processes are
-managed by the functions in "gnunet-service-arm.c" which is controlled
-with "gnunet-arm.c" (main function in that file is ARM's entry point).
-@item The functions responsible for communicating with ARM , starting and
-stopping services -including ARM service itself- are provided by the
-ARM API "arm_api.c".@ Function: GNUNET_ARM_connect() returns to the caller
-an ARM handle after setting it to the caller's context (configuration and
-scheduler in use). This handle can be used afterwards by the caller to
-communicate with ARM. Functions GNUNET_ARM_start_service() and
-GNUNET_ARM_stop_service() are used for starting and stopping services
-respectively.
-@item A typical example of using these basic ARM services can be found in
-file test_arm_api.c. The test case connects to ARM, starts it, then uses
-it to start a service "resolver", stops the "resolver" then stops "ARM".
-@end itemize
-@c ***********************************************************************
-@node Key configuration options
-@subsection Key configuration options
-Configurations for ARM and services should be available in a .conf file
-(As an example, see test_arm_api_data.conf). When running ARM, the
-configuration file to use should be passed to the command:
-@example
-$ gnunet-arm -s -c configuration_to_use.conf
-@end example
-If no configuration is passed, the default configuration file will be used
-(see GNUNET_PREFIX/share/gnunet/defaults.conf which is created from
-contrib/defaults.conf).@ Each of the services is having a section starting
-by the service name between square brackets, for example: "[arm]".
-The following options configure how ARM configures or interacts with the
-various services:
-@table @asis
-@item PORT Port number on which the service is listening for incoming TCP
-connections. ARM will start the services should it notice a request at
-this port.
-@item HOSTNAME Specifies on which host the service is deployed. Note
-that ARM can only start services that are running on the local system
-(but will not check that the hostname matches the local machine name).
-This option is used by the @code{gnunet_client_lib.h} implementation to
-determine which system to connect to. The default is "localhost".
-@item BINARY The name of the service binary file.
-@item OPTIONS To be passed to the service.
-@item PREFIX A command to pre-pend to the actual command, for example,
-running a service with "valgrind" or "gdb"
-@item DEBUG Run in debug mode (much verbosity).
-@item START_ON_DEMAND ARM will listen to UNIX domain socket and/or TCP port of
-the service and start the service on-demand.
-@item IMMEDIATE_START ARM will always start this service when the peer
-is started.
-@item ACCEPT_FROM IPv4 addresses the service accepts connections from.
-@item ACCEPT_FROM6 IPv6 addresses the service accepts connections from.
-@end table
-Options that impact the operation of ARM overall are in the "[arm]"
-section. ARM is a normal service and has (except for START_ON_DEMAND) all of the
-options that other services do. In addition, ARM has the
-following options:
-@table @asis
-@item GLOBAL_PREFIX Command to be pre-pended to all services that are
-going to run.
-@item GLOBAL_POSTFIX Global option that will be supplied to all the
-services that are going to run.
-@end table
-@c ***********************************************************************
-@node ARM - Availability
-@subsection ARM - Availability
-As mentioned before, one of the features provided by ARM is starting
-services on demand. Consider the example of one service "client" that
-wants to connect to another service a "server". The "client" will ask ARM
-to run the "server". ARM starts the "server". The "server" starts
-listening to incoming connections. The "client" will establish a
-connection with the "server". And then, they will start to communicate
-together.@ One problem with that scheme is that it's slow!@
-The "client" service wants to communicate with the "server" service at
-once and is not willing wait for it to be started and listening to
-incoming connections before serving its request.@ One solution for that
-problem will be that ARM starts all services as default services. That
-solution will solve the problem, yet, it's not quite practical, for some
-services that are going to be started can never be used or are going to
-be used after a relatively long time.@
-The approach followed by ARM to solve this problem is as follows:
-@itemize @bullet
-@item For each service having a PORT field in the configuration file and
-that is not one of the default services ( a service that accepts incoming
-connections from clients), ARM creates listening sockets for all addresses
-associated with that service.
-@item The "client" will immediately establish a connection with
-the "server".
-@item ARM --- pretending to be the "server" --- will listen on the
-respective port and notice the incoming connection from the "client"
-(but not accept it), instead
-@item Once there is an incoming connection, ARM will start the "server",
-passing on the listen sockets (now, the service is started and can do its
-work).
-@item Other client services now can directly connect directly to the
-"server".
-@end itemize
-@c ***********************************************************************
-@node Reliability
-@subsection Reliability
-One of the features provided by ARM, is the automatic restart of crashed
-services.@ ARM needs to know which of the running services died. Function
-"gnunet-service-arm.c/maint_child_death()" is responsible for that. The
-function is scheduled to run upon receiving a SIGCHLD signal. The
-function, then, iterates ARM's list of services running and monitors
-which service has died (crashed). For all crashing services, ARM restarts
-them.@
-Now, considering the case of a service having a serious problem causing it
-to crash each time it's started by ARM. If ARM keeps blindly restarting
-such a service, we are going to have the pattern:
-start-crash-restart-crash-restart-crash and so forth!! Which is of course
-not practical.@
-For that reason, ARM schedules the service to be restarted after waiting
-for some delay that grows exponentially with each crash/restart of that
-service.@ To clarify the idea, considering the following example:
-@itemize @bullet
-@item Service S crashed.
-@item ARM receives the SIGCHLD and inspects its list of services to find
-the dead one(s).
-@item ARM finds S dead and schedules it for restarting after "backoff"
-time which is initially set to 1ms. ARM will double the backoff time
-correspondent to S (now backoff(S) = 2ms)
-@item Because there is a severe problem with S, it crashed again.
-@item Again ARM receives the SIGCHLD and detects that it's S again that's
-crashed. ARM schedules it for restarting but after its new backoff time
-(which became 2ms), and doubles its backoff time (now backoff(S) = 4).
-@item and so on, until backoff(S) reaches a certain threshold
-(@code{EXPONENTIAL_BACKOFF_THRESHOLD} is set to half an hour),
-after reaching it, backoff(S) will remain half an hour,
-hence ARM won't be busy for a lot of time trying to restart a
-problematic service.
-@end itemize
-@cindex TRANSPORT Subsystem
-@node TRANSPORT Subsystem
-@section TRANSPORT Subsystem
-This chapter documents how the GNUnet transport subsystem works. The
-GNUnet transport subsystem consists of three main components: the
-transport API (the interface used by the rest of the system to access the
-transport service), the transport service itself (most of the interesting
-functions, such as choosing transports, happens here) and the transport
-plugins. A transport plugin is a concrete implementation for how two
-GNUnet peers communicate; many plugins exist, for example for
-communication via TCP, UDP, HTTP, HTTPS and others. Finally, the
-transport subsystem uses supporting code, especially the NAT/UPnP
-library to help with tasks such as NAT traversal.
-Key tasks of the transport service include:
-@itemize @bullet
-@item Create our HELLO message, notify clients and neighbours if our HELLO
-changes (using NAT library as necessary)
-@item Validate HELLOs from other peers (send PING), allow other peers to
-validate our HELLO's addresses (send PONG)
-@item Upon request, establish connections to other peers (using address
-selection from ATS subsystem) and maintain them (again using PINGs and
-PONGs) as long as desired
-@item Accept incoming connections, give ATS service the opportunity to
-switch communication channels
-@item Notify clients about peers that have connected to us or that have
-been disconnected from us
-@item If a (stateful) connection goes down unexpectedly (without explicit
-DISCONNECT), quickly attempt to recover (without notifying clients) but do
-notify clients quickly if reconnecting fails
-@item Send (payload) messages arriving from clients to other peers via
-transport plugins and receive messages from other peers, forwarding
-those to clients
-@item Enforce inbound traffic limits (using flow-control if it is
-applicable); outbound traffic limits are enforced by CORE, not by us (!)
-@item Enforce restrictions on P2P connection as specified by the blacklist
-configuration and blacklisting clients
-@end itemize
-Note that the term "clients" in the list above really refers to the
-GNUnet-CORE service, as CORE is typically the only client of the
-transport service.
-@menu
-* Address validation protocol::
-@end menu
-@node Address validation protocol
-@subsection Address validation protocol
-This section documents how the GNUnet transport service validates
-connections with other peers. It is a high-level description of the
-protocol necessary to understand the details of the implementation. It
-should be noted that when we talk about PING and PONG messages in this
-section, we refer to transport-level PING and PONG messages, which are
-different from core-level PING and PONG messages (both in implementation
-and function).
-The goal of transport-level address validation is to minimize the chances
-of a successful man-in-the-middle attack against GNUnet peers on the
-transport level. Such an attack would not allow the adversary to decrypt
-the P2P transmissions, but a successful attacker could at least measure
-traffic volumes and latencies (raising the adversaries capabilities by
-those of a global passive adversary in the worst case). The scenarios we
-are concerned about is an attacker, Mallory, giving a @code{HELLO} to
-Alice that claims to be for Bob, but contains Mallory's IP address
-instead of Bobs (for some transport).
-Mallory would then forward the traffic to Bob (by initiating a
-connection to Bob and claiming to be Alice). As a further
-complication, the scheme has to work even if say Alice is behind a NAT
-without traversal support and hence has no address of her own (and thus
-Alice must always initiate the connection to Bob).
-An additional constraint is that @code{HELLO} messages do not contain a
-cryptographic signature since other peers must be able to edit
-(i.e. remove) addresses from the @code{HELLO} at any time (this was
-not true in GNUnet 0.8.x). A basic @strong{assumption} is that each peer
-knows the set of possible network addresses that it @strong{might}
-be reachable under (so for example, the external IP address of the
-NAT plus the LAN address(es) with the respective ports).
-The solution is the following. If Alice wants to validate that a given
-address for Bob is valid (i.e. is actually established @strong{directly}
-with the intended target), she sends a PING message over that connection
-to Bob. Note that in this case, Alice initiated the connection so only
-Alice knows which address was used for sure (Alice may be behind NAT, so
-whatever address Bob sees may not be an address Alice knows she has).
-Bob checks that the address given in the @code{PING} is actually one
-of Bob's addresses (ie: does not belong to Mallory), and if it is,
-sends back a @code{PONG} (with a signature that says that Bob
-owns/uses the address from the @code{PING}).
-Alice checks the signature and is happy if it is valid and the address
-in the @code{PONG} is the address Alice used.
-This is similar to the 0.8.x protocol where the @code{HELLO} contained a
-signature from Bob for each address used by Bob.
-Here, the purpose code for the signature is
-@code{GNUNET_SIGNATURE_PURPOSE_TRANSPORT_PONG_OWN}. After this, Alice will
-remember Bob's address and consider the address valid for a while (12h in
-the current implementation). Note that after this exchange, Alice only
-considers Bob's address to be valid, the connection itself is not
-considered 'established'. In particular, Alice may have many addresses
-for Bob that Alice considers valid.
-The @code{PONG} message is protected with a nonce/challenge against replay
-attacks (@uref{http://en.wikipedia.org/wiki/Replay_attack, replay})
-and uses an expiration time for the signature (but those are almost
-implementation details).
-@cindex NAT library
-@node NAT library
-@section NAT library
-The goal of the GNUnet NAT library is to provide a general-purpose API for
-NAT traversal @strong{without} third-party support. So protocols that
-involve contacting a third peer to help establish a connection between
-two peers are outside of the scope of this API. That does not mean that
-GNUnet doesn't support involving a third peer (we can do this with the
-distance-vector transport or using application-level protocols), it just
-means that the NAT API is not concerned with this possibility. The API is
-written so that it will work for IPv6-NAT in the future as well as
-current IPv4-NAT. Furthermore, the NAT API is always used, even for peers
-that are not behind NAT --- in that case, the mapping provided is simply
-the identity.
-NAT traversal is initiated by calling @code{GNUNET_NAT_register}. Given a
-set of addresses that the peer has locally bound to (TCP or UDP), the NAT
-library will return (via callback) a (possibly longer) list of addresses
-the peer @strong{might} be reachable under. Internally, depending on the
-configuration, the NAT library will try to punch a hole (using UPnP) or
-just "know" that the NAT was manually punched and generate the respective
-external IP address (the one that should be globally visible) based on
-the given information.
-The NAT library also supports ICMP-based NAT traversal. Here, the other
-peer can request connection-reversal by this peer (in this special case,
-the peer is even allowed to configure a port number of zero). If the NAT
-library detects a connection-reversal request, it returns the respective
-target address to the client as well. It should be noted that
-connection-reversal is currently only intended for TCP, so other plugins
-@strong{must} pass @code{NULL} for the reversal callback. Naturally, the
-NAT library also supports requesting connection reversal from a remote
-peer (@code{GNUNET_NAT_run_client}).
-Once initialized, the NAT handle can be used to test if a given address is
-possibly a valid address for this peer (@code{GNUNET_NAT_test_address}).
-This is used for validating our addresses when generating PONGs.
-Finally, the NAT library contains an API to test if our NAT configuration
-is correct. Using @code{GNUNET_NAT_test_start} @strong{before} binding to
-the respective port, the NAT library can be used to test if the
-configuration works. The test function act as a local client, initialize
-the NAT traversal and then contact a @code{gnunet-nat-server} (running by
-default on @code{gnunet.org}) and ask for a connection to be established.
-This way, it is easy to test if the current NAT configuration is valid.
-@node Distance-Vector plugin
-@section Distance-Vector plugin
-The Distance Vector (DV) transport is a transport mechanism that allows
-peers to act as relays for each other, thereby connecting peers that would
-otherwise be unable to connect. This gives a larger connection set to
-applications that may work better with more peers to choose from (for
-example, File Sharing and/or DHT).
-The Distance Vector transport essentially has two functions. The first is
-"gossiping" connection information about more distant peers to directly
-connected peers. The second is taking messages intended for non-directly
-connected peers and encapsulating them in a DV wrapper that contains the
-required information for routing the message through forwarding peers. Via
-gossiping, optimal routes through the known DV neighborhood are discovered
-and utilized and the message encapsulation provides some benefits in
-addition to simply getting the message from the correct source to the
-proper destination.
-The gossiping function of DV provides an up to date routing table of
-peers that are available up to some number of hops. We call this a
-fisheye view of the network (like a fish, nearby objects are known while
-more distant ones unknown). Gossip messages are sent only to directly
-connected peers, but they are sent about other knowns peers within the
-"fisheye distance". Whenever two peers connect, they immediately gossip
-to each other about their appropriate other neighbors. They also gossip
-about the newly connected peer to previously
-connected neighbors. In order to keep the routing tables up to date,
-disconnect notifications are propagated as gossip as well (because
-disconnects may not be sent/received, timeouts are also used remove
-stagnant routing table entries).
-Routing of messages via DV is straightforward. When the DV transport is
-notified of a message destined for a non-direct neighbor, the appropriate
-forwarding peer is selected, and the base message is encapsulated in a DV
-message which contains information about the initial peer and the intended
-recipient. At each forwarding hop, the initial peer is validated (the
-forwarding peer ensures that it has the initial peer in its neighborhood,
-otherwise the message is dropped). Next the base message is
-re-encapsulated in a new DV message for the next hop in the forwarding
-chain (or delivered to the current peer, if it has arrived at the
-destination).
-Assume a three peer network with peers Alice, Bob and Carol. Assume that
-@example
-Alice <-> Bob and Bob <-> Carol
-@end example
-@noindent
-are direct (e.g. over TCP or UDP transports) connections, but that
-Alice cannot directly connect to Carol.
-This may be the case due to NAT or firewall restrictions, or perhaps
-based on one of the peers respective configurations. If the Distance
-Vector transport is enabled on all three peers, it will automatically
-discover (from the gossip protocol) that Alice and Carol can connect via
-Bob and provide a "virtual" Alice <-> Carol connection. Routing between
-Alice and Carol happens as follows; Alice creates a message destined for
-Carol and notifies the DV transport about it. The DV transport at Alice
-looks up Carol in the routing table and finds that the message must be
-sent through Bob for Carol. The message is encapsulated setting Alice as
-the initiator and Carol as the destination and sent to Bob. Bob receives
-the messages, verifies that both Alice and Carol are known to Bob, and
-re-wraps the message in a new DV message for Carol.
-The DV transport at Carol receives this message, unwraps the original
-message, and delivers it to Carol as though it came directly from Alice.
-@cindex SMTP plugin
-@node SMTP plugin
-@section SMTP plugin
-@c TODO: Update!
-This section describes the new SMTP transport plugin for GNUnet as it
-exists in the 0.7.x and 0.8.x branch. SMTP support is currently not
-available in GNUnet 0.9.x. This page also describes the transport layer
-abstraction (as it existed in 0.7.x and 0.8.x) in more detail and gives
-some benchmarking results. The performance results presented are quite
-old and maybe outdated at this point.
-For the readers in the year 2019, you will notice by the mention of
-version 0.7, 0.8, and 0.9 that this section has to be taken with your
-usual grain of salt and be updated eventually.
-@itemize @bullet
-@item Why use SMTP for a peer-to-peer transport?
-@item SMTPHow does it work?
-@item How do I configure my peer?
-@item How do I test if it works?
-@item How fast is it?
-@item Is there any additional documentation?
-@end itemize
-@menu
-* Why use SMTP for a peer-to-peer transport?::
-* How does it work?::
-* How do I configure my peer?::
-* How do I test if it works?::
-* How fast is it?::
-@end menu
-@node Why use SMTP for a peer-to-peer transport?
-@subsection Why use SMTP for a peer-to-peer transport?
-There are many reasons why one would not want to use SMTP:
-@itemize @bullet
-@item SMTP is using more bandwidth than TCP, UDP or HTTP
-@item SMTP has a much higher latency.
-@item SMTP requires significantly more computation (encoding and decoding
-time) for the peers.
-@item SMTP is significantly more complicated to configure.
-@item SMTP may be abused by tricking GNUnet into sending mail to@
-non-participating third parties.
-@end itemize
-So why would anybody want to use SMTP?
-@itemize @bullet
-@item SMTP can be used to contact peers behind NAT boxes (in virtual
-private networks).
-@item SMTP can be used to circumvent policies that limit or prohibit
-peer-to-peer traffic by masking as "legitimate" traffic.
-@item SMTP uses E-mail addresses which are independent of a specific IP,
-which can be useful to address peers that use dynamic IP addresses.
-@item SMTP can be used to initiate a connection (e.g. initial address
-exchange) and peers can then negotiate the use of a more efficient
-protocol (e.g. TCP) for the actual communication.
-@end itemize
-In summary, SMTP can for example be used to send a message to a peer
-behind a NAT box that has a dynamic IP to tell the peer to establish a
-TCP connection to a peer outside of the private network. Even an
-extraordinary overhead for this first message would be irrelevant in this
-type of situation.
-@node How does it work?
-@subsection How does it work?
-When a GNUnet peer needs to send a message to another GNUnet peer that has
-advertised (only) an SMTP transport address, GNUnet base64-encodes the
-message and sends it in an E-mail to the advertised address. The
-advertisement contains a filter which is placed in the E-mail header,
-such that the receiving host can filter the tagged E-mails and forward it
-to the GNUnet peer process. The filter can be specified individually by
-each peer and be changed over time. This makes it impossible to censor
-GNUnet E-mail messages by searching for a generic filter.
-@node How do I configure my peer?
-@subsection How do I configure my peer?
-First, you need to configure @code{procmail} to filter your inbound E-mail
-for GNUnet traffic. The GNUnet messages must be delivered into a pipe, for
-example @code{/tmp/gnunet.smtp}. You also need to define a filter that is
-used by @command{procmail} to detect GNUnet messages. You are free to
-choose whichever filter you like, but you should make sure that it does
-not occur in your other E-mail. In our example, we will use
-@code{X-mailer: GNUnet}. The @code{~/.procmailrc} configuration file then
-looks like this:
-@example
-:0:
-* ^X-mailer: GNUnet
-/tmp/gnunet.smtp
-# where do you want your other e-mail delivered to
-# (default: /var/spool/mail/)
-:0: /var/spool/mail/
-@end example
-After adding this file, first make sure that your regular E-mail still
-works (e.g. by sending an E-mail to yourself). Then edit the GNUnet
-configuration. In the section @code{SMTP} you need to specify your E-mail
-address under @code{EMAIL}, your mail server (for outgoing mail) under
-@code{SERVER}, the filter (X-mailer: GNUnet in the example) under
-@code{FILTER} and the name of the pipe under @code{PIPE}.@ The completed
-section could then look like this:
-@example
-EMAIL = me@@mail.gnu.org MTU = 65000 SERVER = mail.gnu.org:25 FILTER =
-"X-mailer: GNUnet" PIPE = /tmp/gnunet.smtp
-@end example
-Finally, you need to add @code{smtp} to the list of @code{TRANSPORTS} in
-the @code{GNUNETD} section. GNUnet peers will use the E-mail address that
-you specified to contact your peer until the advertisement times out.
-Thus, if you are not sure if everything works properly or if you are not
-planning to be online for a long time, you may want to configure this
-timeout to be short, e.g. just one hour. For this, set
-@code{HELLOEXPIRES} to @code{1} in the @code{GNUNETD} section.
-This should be it, but you may probably want to test it first.
-@node How do I test if it works?
-@subsection How do I test if it works?
-Any transport can be subjected to some rudimentary tests using the
-@code{gnunet-transport-check} tool. The tool sends a message to the local
-node via the transport and checks that a valid message is received. While
-this test does not involve other peers and can not check if firewalls or
-other network obstacles prohibit proper operation, this is a great
-testcase for the SMTP transport since it tests pretty much nearly all of
-the functionality.
-@code{gnunet-transport-check} should only be used without running
-@code{gnunetd} at the same time. By default, @code{gnunet-transport-check}
-tests all transports that are specified in the configuration file. But
-you can specifically test SMTP by giving the option
-@code{--transport=smtp}.
-Note that this test always checks if a transport can receive and send.
-While you can configure most transports to only receive or only send
-messages, this test will only work if you have configured the transport
-to send and receive messages.
-@node How fast is it?
-@subsection How fast is it?
-We have measured the performance of the UDP, TCP and SMTP transport layer
-directly and when used from an application using the GNUnet core.
-Measuring just the transport layer gives the better view of the actual
-overhead of the protocol, whereas evaluating the transport from the
-application puts the overhead into perspective from a practical point of
-view.
-The loopback measurements of the SMTP transport were performed on three
-different machines spanning a range of modern SMTP configurations. We
-used a PIII-800 running RedHat 7.3 with the Purdue Computer Science
-configuration which includes filters for spam. We also used a Xenon 2 GHZ
-with a vanilla RedHat 8.0 sendmail configuration. Furthermore, we used
-qmail on a PIII-1000 running Sorcerer GNU Linux (SGL). The numbers for
-UDP and TCP are provided using the SGL configuration. The qmail benchmark
-uses qmail's internal filtering whereas the sendmail benchmarks relies on
-procmail to filter and deliver the mail. We used the transport layer to
-send a message of b bytes (excluding transport protocol headers) directly
-to the local machine. This way, network latency and packet loss on the
-wire have no impact on the timings. n messages were sent sequentially over
-the transport layer, sending message i+1 after the i-th message was
-received. All messages were sent over the same connection and the time to
-establish the connection was not taken into account since this overhead is
-minuscule in practice --- as long as a connection is used for a
-significant number of messages.
-@multitable @columnfractions .20 .15 .15 .15 .15 .15
-@headitem Transport @tab UDP @tab TCP @tab SMTP (Purdue sendmail)
-@tab SMTP (RH 8.0) @tab SMTP (SGL qmail)
-@item  11 bytes @tab 31 ms @tab 55 ms @tab  781 s @tab 77 s @tab 24 s
-@item  407 bytes @tab 37 ms @tab 62 ms @tab  789 s @tab 78 s @tab 25 s
-@item 1,221 bytes @tab 46 ms @tab 73 ms @tab  804 s @tab 78 s @tab 25 s
-@end multitable
-The benchmarks show that UDP and TCP are, as expected, both significantly
-faster compared with any of the SMTP services. Among the SMTP
-implementations, there can be significant differences depending on the
-SMTP configuration. Filtering with an external tool like procmail that
-needs to re-parse its configuration for each mail can be very expensive.
-Applying spam filters can also significantly impact the performance of
-the underlying SMTP implementation. The microbenchmark shows that SMTP
-can be a viable solution for initiating peer-to-peer sessions: a couple of
-seconds to connect to a peer are probably not even going to be noticed by
-users. The next benchmark measures the possible throughput for a
-transport. Throughput can be measured by sending multiple messages in
-parallel and measuring packet loss. Note that not only UDP but also the
-TCP transport can actually loose messages since the TCP implementation
-drops messages if the @code{write} to the socket would block. While the
-SMTP protocol never drops messages itself, it is often so
-slow that only a fraction of the messages can be sent and received in the
-given time-bounds. For this benchmark we report the message loss after
-allowing t time for sending m messages. If messages were not sent (or
-received) after an overall timeout of t, they were considered lost. The
-benchmark was performed using two Xeon 2 GHZ machines running RedHat 8.0
-with sendmail. The machines were connected with a direct 100 MBit Ethernet
-connection.@ Figures udp1200, tcp1200 and smtp-MTUs show that the
-throughput for messages of size 1,200 octets is 2,343 kbps, 3,310 kbps
-and 6 kbps for UDP, TCP and SMTP respectively. The high per-message
-overhead of SMTP can be improved by increasing the MTU, for example, an
-MTU of 12,000 octets improves the throughput to 13 kbps as figure
-smtp-MTUs shows. Our research paper) has some more details on the
-benchmarking results.
-@cindex Bluetooth plugin
-@node Bluetooth plugin
-@section Bluetooth plugin
-This page describes the new Bluetooth transport plugin for GNUnet. The
-plugin is still in the testing stage so don't expect it to work
-perfectly. If you have any questions or problems just post them here or
-ask on the IRC channel.
-@itemize @bullet
-@item What do I need to use the Bluetooth plugin transport?
-@item BluetoothHow does it work?
-@item What possible errors should I be aware of?
-@item How do I configure my peer?
-@item How can I test it?
-@end itemize
-@menu
-* What do I need to use the Bluetooth plugin transport?::
-* How does it work2?::
-* What possible errors should I be aware of?::
-* How do I configure my peer2?::
-* How can I test it?::
-* The implementation of the Bluetooth transport plugin::
-@end menu
-@node What do I need to use the Bluetooth plugin transport?
-@subsection What do I need to use the Bluetooth plugin transport?
-If you are a GNU/Linux user and you want to use the Bluetooth
-transport plugin you should install the
-@command{BlueZ} development libraries (if they aren't already
-installed).
-For instructions about how to install the libraries you should
-check out the BlueZ site
-(@uref{http://www.bluez.org/, http://www.bluez.org}). If you don't know if
-you have the necessary libraries, don't worry, just run the GNUnet
-configure script and you will be able to see a notification at the end
-which will warn you if you don't have the necessary libraries.
-@c If you are a Windows user you should have installed the
-@c @emph{MinGW}/@emph{MSys2} with the latest updates (especially the
-@c @emph{ws2bth} header). If this is your first build of GNUnet on Windows
-@c you should check out the SBuild repository. It will semi-automatically
-@c assembles a @emph{MinGW}/@emph{MSys2} installation with a lot of extra
-@c packages which are needed for the GNUnet build. So this will ease your
-@c work!@ Finally you just have to be sure that you have the correct drivers
-@c for your Bluetooth device installed and that your device is on and in a
-@c discoverable mode. The Windows Bluetooth Stack supports only the RFCOMM
-@c protocol so we cannot turn on your device programmatically!
-@c FIXME: Change to unique title
-@node How does it work2?
-@subsection How does it work2?
-The Bluetooth transport plugin uses virtually the same code as the WLAN
-plugin and only the helper binary is different. The helper takes a single
-argument, which represents the interface name and is specified in the
-configuration file. Here are the basic steps that are followed by the
-helper binary used on GNU/Linux:
-@itemize @bullet
-@item it verifies if the name corresponds to a Bluetooth interface name
-@item it verifies if the interface is up (if it is not, it tries to bring
-it up)
-@item it tries to enable the page and inquiry scan in order to make the
-device discoverable and to accept incoming connection requests
-@emph{The above operations require root access so you should start the
-transport plugin with root privileges.}
-@item it finds an available port number and registers a SDP service which
-will be used to find out on which port number is the server listening on
-and switch the socket in listening mode
-@item it sends a HELLO message with its address
-@item finally it forwards traffic from the reading sockets to the STDOUT
-and from the STDIN to the writing socket
-@end itemize
-Once in a while the device will make an inquiry scan to discover the
-nearby devices and it will send them randomly HELLO messages for peer
-discovery.
-@node What possible errors should I be aware of?
-@subsection What possible errors should I be aware of?
-@emph{This section is dedicated for GNU/Linux users}
-Well there are many ways in which things could go wrong but I will try to
-present some tools that you could use to debug and some scenarios.
-@itemize @bullet
-@item @code{bluetoothd -n -d} : use this command to enable logging in the
-foreground and to print the logging messages
-@item @code{hciconfig}: can be used to configure the Bluetooth devices.
-If you run it without any arguments it will print information about the
-state of the interfaces. So if you receive an error that the device
-couldn't be brought up you should try to bring it manually and to see if
-it works (use @code{hciconfig -a hciX up}). If you can't and the
-Bluetooth address has the form 00:00:00:00:00:00 it means that there is
-something wrong with the D-Bus daemon or with the Bluetooth daemon. Use
-@code{bluetoothd} tool to see the logs
-@item @code{sdptool} can be used to control and interrogate SDP servers.
-If you encounter problems regarding the SDP server (like the SDP server is
-down) you should check out if the D-Bus daemon is running correctly and to
-see if the Bluetooth daemon started correctly(use @code{bluetoothd} tool).
-Also, sometimes the SDP service could work but somehow the device couldn't
-register its service. Use @code{sdptool browse [dev-address]} to see if
-the service is registered. There should be a service with the name of the
-interface and GNUnet as provider.
-@item @code{hcitool} : another useful tool which can be used to configure
-the device and to send some particular commands to it.
-@item @code{hcidump} : could be used for low level debugging
-@end itemize
-@c FIXME: A more unique name
-@node How do I configure my peer2?
-@subsection How do I configure my peer2?
-On GNU/Linux, you just have to be sure that the interface name
-corresponds to the one that you want to use.
-Use the @code{hciconfig} tool to check that.
-By default it is set to hci0 but you can change it.
-A basic configuration looks like this:
-@example
-[transport-bluetooth]
-# Name of the interface (typically hciX)
-INTERFACE = hci0
-# Real hardware, no testing
-TESTMODE = 0 TESTING_IGNORE_KEYS = ACCEPT_FROM;
-@end example
-In order to use the Bluetooth transport plugin when the transport service
-is started, you must add the plugin name to the default transport service
-plugins list. For example:
-@example
-[transport] ...  PLUGINS = dns bluetooth ...
-@end example
-If you want to use only the Bluetooth plugin set
-@emph{PLUGINS = bluetooth}
-On Windows, you cannot specify which device to use. The only thing that
-you should do is to add @emph{bluetooth} on the plugins list of the
-transport service.
-@node How can I test it?
-@subsection How can I test it?
-If you have two Bluetooth devices on the same machine and you are using
-GNU/Linux you must:
-@itemize @bullet
-@item create two different file configuration (one which will use the
-first interface (@emph{hci0}) and the other which will use the second
-interface (@emph{hci1})). Let's name them @emph{peer1.conf} and
-@emph{peer2.conf}.
-@item run @emph{gnunet-peerinfo -c peerX.conf -s} in order to generate the
-peers private keys. The @strong{X} must be replace with 1 or 2.
-@item run @emph{gnunet-arm -c peerX.conf -s -i=transport} in order to
-start the transport service. (Make sure that you have "bluetooth" on the
-transport plugins list if the Bluetooth transport service doesn't start.)
-@item run @emph{gnunet-peerinfo -c peer1.conf -s} to get the first peer's
-ID. If you already know your peer ID (you saved it from the first
-command), this can be skipped.
-@item run @emph{gnunet-transport -c peer2.conf -p=PEER1_ID -s} to start
-sending data for benchmarking to the other peer.
-@end itemize
-This scenario will try to connect the second peer to the first one and
-then start sending data for benchmarking.
-@c On Windows you cannot test the plugin functionality using two Bluetooth
-@c devices from the same machine because after you install the drivers there
-@c will occur some conflicts between the Bluetooth stacks. (At least that is
-@c what happened on my machine : I wasn't able to use the Bluesoleil stack and
-@c the WINDCOMM one in the same time).
-If you have two different machines and your configuration files are good
-you can use the same scenario presented on the beginning of this section.
-Another way to test the plugin functionality is to create your own
-application which will use the GNUnet framework with the Bluetooth
-transport service.
-@node The implementation of the Bluetooth transport plugin
-@subsection The implementation of the Bluetooth transport plugin
-This page describes the implementation of the Bluetooth transport plugin.
-First I want to remind you that the Bluetooth transport plugin uses
-virtually the same code as the WLAN plugin and only the helper binary is
-different. Also the scope of the helper binary from the Bluetooth
-transport plugin is the same as the one used for the WLAN transport
-plugin: it accesses the interface and then it forwards traffic in both
-directions between the Bluetooth interface and stdin/stdout of the
-process involved.
-The Bluetooth plugin transport could be used both on GNU/Linux and Windows
-platforms.
-@itemize @bullet
-@item Linux functionality
-@c @item Windows functionality
-@item Pending Features
-@end itemize
-@menu
-* Linux functionality::
-* THE INITIALIZATION::
-* THE LOOP::
-* Details about the broadcast implementation::
-@c * Windows functionality::
-* Pending features::
-@end menu
-@node Linux functionality
-@subsubsection Linux functionality
-In order to implement the plugin functionality on GNU/Linux I
-used the BlueZ stack.
-For the communication with the other devices I used the RFCOMM
-protocol. Also I used the HCI protocol to gain some control over the
-device. The helper binary takes a single argument (the name of the
-Bluetooth interface) and is separated in two stages:
-@c %** 'THE INITIALIZATION' should be in bigger letters or stand out, not
-@c %** starting a new section?
-@node THE INITIALIZATION
-@subsubsection THE INITIALIZATION
-@itemize @bullet
-@item first, it checks if we have root privileges
-(@emph{Remember that we need to have root privileges in order to be able
-to bring the interface up if it is down or to change its state.}).
-@item second, it verifies if the interface with the given name exists.
-@strong{If the interface with that name exists and it is a Bluetooth
-interface:}
-@item it creates a RFCOMM socket which will be used for listening and call
-the @emph{open_device} method
-On the @emph{open_device} method:
-@itemize @bullet
-@item creates a HCI socket used to send control events to the device
-@item searches for the device ID using the interface name
-@item saves the device MAC address
-@item checks if the interface is down and tries to bring it UP
-@item checks if the interface is in discoverable mode and tries to make it
-discoverable
-@item closes the HCI socket and binds the RFCOMM one
-@item switches the RFCOMM socket in listening mode
-@item registers the SDP service (the service will be used by the other
-devices to get the port on which this device is listening on)
-@end itemize
-@item drops the root privileges
-@strong{If the interface is not a Bluetooth interface the helper exits
-with a suitable error}
-@end itemize
-@c %** Same as for @node entry above
-@node THE LOOP
-@subsubsection THE LOOP
-The helper binary uses a list where it saves all the connected neighbour
-devices (@emph{neighbours.devices}) and two buffers (@emph{write_pout} and
-@emph{write_std}). The first message which is send is a control message
-with the device's MAC address in order to announce the peer presence to
-the neighbours. Here are a short description of what happens in the main
-loop:
-@itemize @bullet
-@item Every time when it receives something from the STDIN it processes
-the data and saves the message in the first buffer (@emph{write_pout}).
-When it has something in the buffer, it gets the destination address from
-the buffer, searches the destination address in the list (if there is no
-connection with that device, it creates a new one and saves it to the
-list) and sends the message.
-@item Every time when it receives something on the listening socket it
-accepts the connection and saves the socket on a list with the reading
-sockets. @item Every time when it receives something from a reading
-socket it parses the message, verifies the CRC and saves it in the
-@emph{write_std} buffer in order to be sent later to the STDOUT.
-@end itemize
-So in the main loop we use the select function to wait until one of the
-file descriptor saved in one of the two file descriptors sets used is
-ready to use. The first set (@emph{rfds}) represents the reading set and
-it could contain the list with the reading sockets, the STDIN file
-descriptor or the listening socket. The second set (@emph{wfds}) is the
-writing set and it could contain the sending socket or the STDOUT file
-descriptor. After the select function returns, we check which file
-descriptor is ready to use and we do what is supposed to do on that kind
-of event. @emph{For example:} if it is the listening socket then we
-accept a new connection and save the socket in the reading list; if it is
-the STDOUT file descriptor, then we write to STDOUT the message from the
-@emph{write_std} buffer.
-To find out on which port a device is listening on we connect to the local
-SDP server and search the registered service for that device.
-@emph{You should be aware of the fact that if the device fails to connect
-to another one when trying to send a message it will attempt one more
-time. If it fails again, then it skips the message.}
-@emph{Also you should know that the transport Bluetooth plugin has
-support for @strong{broadcast messages}.}
-@node Details about the broadcast implementation
-@subsubsection Details about the broadcast implementation
-First I want to point out that the broadcast functionality for the CONTROL
-messages is not implemented in a conventional way. Since the inquiry scan
-time is too big and it will take some time to send a message to all the
-discoverable devices I decided to tackle the problem in a different way.
-Here is how I did it:
-@itemize @bullet
-@item If it is the first time when I have to broadcast a message I make an
-inquiry scan and save all the devices' addresses to a vector.
-@item After the inquiry scan ends I take the first address from the list
-and I try to connect to it. If it fails, I try to connect to the next one.
-If it succeeds, I save the socket to a list and send the message to the
-device.
-@item When I have to broadcast another message, first I search on the list
-for a new device which I'm not connected to. If there is no new device on
-the list I go to the beginning of the list and send the message to the
-old devices. After 5 cycles I make a new inquiry scan to check out if
-there are new discoverable devices and save them to the list. If there
-are no new discoverable devices I reset the cycling counter and go again
-through the old list and send messages to the devices saved in it.
-@end itemize
-@strong{Therefore}:
-@itemize @bullet
-@item every time when I have a broadcast message I look up on the list
-for a new device and send the message to it
-@item if I reached the end of the list for 5 times and I'm connected to
-all the devices from the list I make a new inquiry scan.
-@emph{The number of the list's cycles after an inquiry scan could be
-increased by redefining the MAX_LOOPS variable}
-@item when there are no new devices I send messages to the old ones.
-@end itemize
-Doing so, the broadcast control messages will reach the devices but with
-delay.
-@emph{NOTICE:} When I have to send a message to a certain device first I
-check on the broadcast list to see if we are connected to that device. If
-not we try to connect to it and in case of success we save the address and
-the socket on the list. If we are already connected to that device we
-simply use the socket.
-@c @node Windows functionality
-@c @subsubsection Windows functionality
-@c For Windows I decided to use the Microsoft Bluetooth stack which has the
-@c advantage of coming standard from Windows XP SP2. The main disadvantage is
-@c that it only supports the RFCOMM protocol so we will not be able to have
-@c a low level control over the Bluetooth device. Therefore it is the user
-@c responsibility to check if the device is up and in the discoverable mode.
-@c Also there are no tools which could be used for debugging in order to read
-@c the data coming from and going to a Bluetooth device, which obviously
-@c hindered my work. Another thing that slowed down the implementation of the
-@c plugin (besides that I wasn't too accommodated with the win32 API) was that
-@c there were some bugs on MinGW regarding the Bluetooth. Now they are solved
-@c but you should keep in mind that you should have the latest updates
-@c (especially the @emph{ws2bth} header).
-@c Besides the fact that it uses the Windows Sockets, the Windows
-@c implementation follows the same principles as the GNU/Linux one:
-@c @itemize @bullet
-@c @item It has a initialization part where it initializes the
-@c Windows Sockets, creates a RFCOMM socket which will be binded and switched
-@c to the listening mode and registers a SDP service. In the Microsoft
-@c Bluetooth API there are two ways to work with the SDP:
-@c @itemize @bullet
-@c @item an easy way which works with very simple service records
-@c @item a hard way which is useful when you need to update or to delete the
-@c record
-@c @end itemize
-@c @end itemize
-@c Since I only needed the SDP service to find out on which port the device
-@c is listening on and that did not change, I decided to use the easy way.
-@c In order to register the service I used the @emph{WSASetService} function
-@c and I generated the @emph{Universally Unique Identifier} with the
-@c @emph{guidgen.exe} Windows's tool.
-@c In the loop section the only difference from the GNU/Linux implementation
-@c is that I used the @code{GNUNET_NETWORK} library for
-@c functions like @emph{accept}, @emph{bind}, @emph{connect} or
-@c @emph{select}. I decided to use the
-@c @code{GNUNET_NETWORK} library because I also needed to interact
-@c with the STDIN and STDOUT handles and on Windows
-@c the select function is only defined for sockets,
-@c and it will not work for arbitrary file handles.
-@c Another difference between GNU/Linux and Windows implementation is that in
-@c GNU/Linux, the Bluetooth address is represented in 48 bits
-@c while in Windows is represented in 64 bits.
-@c Therefore I had to do some changes on @emph{plugin_transport_wlan} header.
-@c Also, currently on Windows the Bluetooth plugin doesn't have support for
-@c broadcast messages. When it receives a broadcast message it will skip it.
-@node Pending features
-@subsubsection Pending features
-@itemize @bullet
-@c @item Implement the broadcast functionality on Windows @emph{(currently
-@c working on)}
-@item Implement a testcase for the helper :@ @emph{The testcase
-consists of a program which emulates the plugin and uses the helper. It
-will simulate connections, disconnections and data transfers.}
-@end itemize
-If you have a new idea about a feature of the plugin or suggestions about
-how I could improve the implementation you are welcome to comment or to
-contact me.
-@node WLAN plugin
-@section WLAN plugin
-This section documents how the wlan transport plugin works. Parts which
-are not implemented yet or could be better implemented are described at
-the end.
-@cindex ATS Subsystem
-@node ATS Subsystem
-@section ATS Subsystem
-ATS stands for "automatic transport selection", and the function of ATS in
-GNUnet is to decide on which address (and thus transport plugin) should
-be used for two peers to communicate, and what bandwidth limits should be
-imposed on such an individual connection. To help ATS make an informed
-decision, higher-level services inform the ATS service about their
-requirements and the quality of the service rendered. The ATS service
-also interacts with the transport service to be appraised of working
-addresses and to communicate its resource allocation decisions. Finally,
-the ATS service's operation can be observed using a monitoring API.
-The main logic of the ATS service only collects the available addresses,
-their performance characteristics and the applications requirements, but
-does not make the actual allocation decision. This last critical step is
-left to an ATS plugin, as we have implemented (currently three) different
-allocation strategies which differ significantly in their performance and
-maturity, and it is still unclear if any particular plugin is generally
-superior.
-@cindex CORE Subsystem
-@node CORE Subsystem
-@section CORE Subsystem
-The CORE subsystem in GNUnet is responsible for securing link-layer
-communications between nodes in the GNUnet overlay network. CORE builds
-on the TRANSPORT subsystem which provides for the actual, insecure,
-unreliable link-layer communication (for example, via UDP or WLAN), and
-then adds fundamental security to the connections:
-@itemize @bullet
-@item confidentiality with so-called perfect forward secrecy; we use
-ECDHE
-(@uref{http://en.wikipedia.org/wiki/Elliptic_curve_Diffie%E2%80%93Hellman, Elliptic-curve Diffie---Hellman})
-powered by Curve25519
-(@uref{http://cr.yp.to/ecdh.html, Curve25519}) for the key
-exchange and then use symmetric encryption, encrypting with both AES-256
-(@uref{http://en.wikipedia.org/wiki/Rijndael, AES-256}) and
-Twofish (@uref{http://en.wikipedia.org/wiki/Twofish, Twofish})
-@item @uref{http://en.wikipedia.org/wiki/Authentication, authentication}
-is achieved by signing the ephemeral keys using Ed25519
-(@uref{http://ed25519.cr.yp.to/, Ed25519}), a deterministic
-variant of ECDSA
-(@uref{http://en.wikipedia.org/wiki/ECDSA, ECDSA})
-@item integrity protection (using SHA-512
-(@uref{http://en.wikipedia.org/wiki/SHA-2, SHA-512}) to do
-encrypt-then-MAC
-(@uref{http://en.wikipedia.org/wiki/Authenticated_encryption, encrypt-then-MAC}))
-@item Replay
-(@uref{http://en.wikipedia.org/wiki/Replay_attack, replay})
-protection (using nonces, timestamps, challenge-response,
-message counters and ephemeral keys)
-@item liveness (keep-alive messages, timeout)
-@end itemize
-@menu
-* Limitations::
-* When is a peer "connected"?::
-* libgnunetcore::
-* The CORE Client-Service Protocol::
-* The CORE Peer-to-Peer Protocol::
-@end menu
-@cindex core subsystem limitations
-@node Limitations
-@subsection Limitations
-CORE does not perform
-@uref{http://en.wikipedia.org/wiki/Routing, routing}; using CORE it is
-only possible to communicate with peers that happen to already be
-"directly" connected with each other. CORE also does not have an
-API to allow applications to establish such "direct" connections --- for
-this, applications can ask TRANSPORT, but TRANSPORT might not be able to
-establish a "direct" connection. The TOPOLOGY subsystem is responsible for
-trying to keep a few "direct" connections open at all times. Applications
-that need to talk to particular peers should use the CADET subsystem, as
-it can establish arbitrary "indirect" connections.
-Because CORE does not perform routing, CORE must only be used directly by
-applications that either perform their own routing logic (such as
-anonymous file-sharing) or that do not require routing, for example
-because they are based on flooding the network. CORE communication is
-unreliable and delivery is possibly out-of-order. Applications that
-require reliable communication should use the CADET service. Each
-application can only queue one message per target peer with the CORE
-service at any time; messages cannot be larger than approximately
-63 kilobytes. If messages are small, CORE may group multiple messages
-(possibly from different applications) prior to encryption. If permitted
-by the application (using the @uref{http://baus.net/on-tcp_cork/, cork}
-option), CORE may delay transmissions to facilitate grouping of multiple
-small messages. If cork is not enabled, CORE will transmit the message as
-soon as TRANSPORT allows it (TRANSPORT is responsible for limiting
-bandwidth and congestion control). CORE does not allow flow control;
-applications are expected to process messages at line-speed. If flow
-control is needed, applications should use the CADET service.
-@cindex when is a peer connected
-@node When is a peer "connected"?
-@subsection When is a peer "connected"?
-In addition to the security features mentioned above, CORE also provides
-one additional key feature to applications using it, and that is a
-limited form of protocol-compatibility checking. CORE distinguishes
-between TRANSPORT-level connections (which enable communication with other
-peers) and application-level connections. Applications using the CORE API
-will (typically) learn about application-level connections from CORE, and
-not about TRANSPORT-level connections. When a typical application uses
-CORE, it will specify a set of message types
-(from @code{gnunet_protocols.h}) that it understands. CORE will then
-notify the application about connections it has with other peers if and
-only if those applications registered an intersecting set of message
-types with their CORE service. Thus, it is quite possible that CORE only
-exposes a subset of the established direct connections to a particular
-application --- and different applications running above CORE might see
-different sets of connections at the same time.
-A special case are applications that do not register a handler for any
-message type.
-CORE assumes that these applications merely want to monitor connections
-(or "all" messages via other callbacks) and will notify those applications
-about all connections. This is used, for example, by the
-@code{gnunet-core} command-line tool to display the active connections.
-Note that it is also possible that the TRANSPORT service has more active
-connections than the CORE service, as the CORE service first has to
-perform a key exchange with connecting peers before exchanging information
-about supported message types and notifying applications about the new
-connection.
-@cindex libgnunetcore
-@node libgnunetcore
-@subsection libgnunetcore
-The CORE API (defined in @file{gnunet_core_service.h}) is the basic
-messaging API used by P2P applications built using GNUnet. It provides
-applications the ability to send and receive encrypted messages to the
-peer's "directly" connected neighbours.
-As CORE connections are generally "direct" connections,@ applications must
-not assume that they can connect to arbitrary peers this way, as "direct"
-connections may not always be possible. Applications using CORE are
-notified about which peers are connected. Creating new "direct"
-connections must be done using the TRANSPORT API.
-The CORE API provides unreliable, out-of-order delivery. While the
-implementation tries to ensure timely, in-order delivery, both message
-losses and reordering are not detected and must be tolerated by the
-application. Most important, the core will NOT perform retransmission if
-messages could not be delivered.
-Note that CORE allows applications to queue one message per connected
-peer. The rate at which each connection operates is influenced by the
-preferences expressed by local application as well as restrictions
-imposed by the other peer. Local applications can express their
-preferences for particular connections using the "performance" API of the
-ATS service.
-Applications that require more sophisticated transmission capabilities
-such as TCP-like behavior, or if you intend to send messages to arbitrary
-remote peers, should use the CADET API.
-The typical use of the CORE API is to connect to the CORE service using
-@code{GNUNET_CORE_connect}, process events from the CORE service (such as
-peers connecting, peers disconnecting and incoming messages) and send
-messages to connected peers using
-@code{GNUNET_CORE_notify_transmit_ready}. Note that applications must
-cancel pending transmission requests if they receive a disconnect event
-for a peer that had a transmission pending; furthermore, queuing more
-than one transmission request per peer per application using the
-service is not permitted.
-The CORE API also allows applications to monitor all communications of the
-peer prior to encryption (for outgoing messages) or after decryption (for
-incoming messages). This can be useful for debugging, diagnostics or to
-establish the presence of cover traffic (for anonymity). As monitoring
-applications are often not interested in the payload, the monitoring
-callbacks can be configured to only provide the message headers (including
-the message type and size) instead of copying the full data stream to the
-monitoring client.
-The init callback of the @code{GNUNET_CORE_connect} function is called
-with the hash of the public key of the peer. This public key is used to
-identify the peer globally in the GNUnet network. Applications are
-encouraged to check that the provided hash matches the hash that they are
-using (as theoretically the application may be using a different
-configuration file with a different private key, which would result in
-hard to find bugs).
-As with most service APIs, the CORE API isolates applications from crashes
-of the CORE service. If the CORE service crashes, the application will see
-disconnect events for all existing connections. Once the connections are
-re-established, the applications will be receive matching connect events.
-@cindex core clinet-service protocol
-@node The CORE Client-Service Protocol
-@subsection The CORE Client-Service Protocol
-This section describes the protocol between an application using the CORE
-service (the client) and the CORE service process itself.
-@menu
-* Setup2::
-* Notifications::
-* Sending::
-@end menu
-@node Setup2
-@subsubsection Setup2
-When a client connects to the CORE service, it first sends a
-@code{InitMessage} which specifies options for the connection and a set of
-message type values which are supported by the application. The options
-bitmask specifies which events the client would like to be notified about.
-The options include:
-@table @asis
-@item GNUNET_CORE_OPTION_NOTHING No notifications
-@item GNUNET_CORE_OPTION_STATUS_CHANGE Peers connecting and disconnecting
-@item GNUNET_CORE_OPTION_FULL_INBOUND All inbound messages (after
-decryption) with full payload
-@item GNUNET_CORE_OPTION_HDR_INBOUND Just the @code{MessageHeader}
-of all inbound messages
-@item GNUNET_CORE_OPTION_FULL_OUTBOUND All outbound
-messages (prior to encryption) with full payload
-@item GNUNET_CORE_OPTION_HDR_OUTBOUND Just the @code{MessageHeader} of all
-outbound messages
-@end table
-Typical applications will only monitor for connection status changes.
-The CORE service responds to the @code{InitMessage} with an
-@code{InitReplyMessage} which contains the peer's identity. Afterwards,
-both CORE and the client can send messages.
-@node Notifications
-@subsubsection Notifications
-The CORE will send @code{ConnectNotifyMessage}s and
-@code{DisconnectNotifyMessage}s whenever peers connect or disconnect from
-the CORE (assuming their type maps overlap with the message types
-registered by the client). When the CORE receives a message that matches
-the set of message types specified during the @code{InitMessage} (or if
-monitoring is enabled in for inbound messages in the options), it sends a
-@code{NotifyTrafficMessage} with the peer identity of the sender and the
-decrypted payload. The same message format (except with
-@code{GNUNET_MESSAGE_TYPE_CORE_NOTIFY_OUTBOUND} for the message type) is
-used to notify clients monitoring outbound messages; here, the peer
-identity given is that of the receiver.
-@node Sending
-@subsubsection Sending
-When a client wants to transmit a message, it first requests a
-transmission slot by sending a @code{SendMessageRequest} which specifies
-the priority, deadline and size of the message. Note that these values
-may be ignored by CORE. When CORE is ready for the message, it answers
-with a @code{SendMessageReady} response. The client can then transmit the
-payload with a @code{SendMessage} message. Note that the actual message
-size in the @code{SendMessage} is allowed to be smaller than the size in
-the original request. A client may at any time send a fresh
-@code{SendMessageRequest}, which then superceeds the previous
-@code{SendMessageRequest}, which is then no longer valid. The client can
-tell which @code{SendMessageRequest} the CORE service's
-@code{SendMessageReady} message is for as all of these messages contain a
-"unique" request ID (based on a counter incremented by the client
-for each request).
-@cindex CORE Peer-to-Peer Protocol
-@node The CORE Peer-to-Peer Protocol
-@subsection The CORE Peer-to-Peer Protocol
-@menu
-* Creating the EphemeralKeyMessage::
-* Establishing a connection::
-* Encryption and Decryption::
-* Type maps::
-@end menu
-@cindex EphemeralKeyMessage creation
-@node Creating the EphemeralKeyMessage
-@subsubsection Creating the EphemeralKeyMessage
-When the CORE service starts, each peer creates a fresh ephemeral (ECC)
-public-private key pair and signs the corresponding
-@code{EphemeralKeyMessage} with its long-term key (which we usually call
-the peer's identity; the hash of the public long term key is what results
-in a @code{struct GNUNET_PeerIdentity} in all GNUnet APIs. The ephemeral
-key is ONLY used for an ECDHE
-(@uref{http://en.wikipedia.org/wiki/Elliptic_curve_Diffie%E2%80%93Hellman, Elliptic-curve Diffie---Hellman})
-exchange by the CORE service to establish symmetric session keys. A peer
-will use the same @code{EphemeralKeyMessage} for all peers for
-@code{REKEY_FREQUENCY}, which is usually 12 hours. After that time, it
-will create a fresh ephemeral key (forgetting the old one) and broadcast
-the new @code{EphemeralKeyMessage} to all connected peers, resulting in
-fresh symmetric session keys. Note that peers independently decide on
-when to discard ephemeral keys; it is not a protocol violation to discard
-keys more often. Ephemeral keys are also never stored to disk; restarting
-a peer will thus always create a fresh ephemeral key. The use of ephemeral
-keys is what provides @uref{http://en.wikipedia.org/wiki/Forward_secrecy, forward secrecy}.
-Just before transmission, the @code{EphemeralKeyMessage} is patched to
-reflect the current sender_status, which specifies the current state of
-the connection from the point of view of the sender. The possible values
-are:
-@itemize @bullet
-@item @code{KX_STATE_DOWN} Initial value, never used on the network
-@item @code{KX_STATE_KEY_SENT} We sent our ephemeral key, do not know the
-key of the other peer
-@item @code{KX_STATE_KEY_RECEIVED} This peer has received a valid
-ephemeral key of the other peer, but we are waiting for the other peer to
-confirm it's authenticity (ability to decode) via challenge-response.
-@item @code{KX_STATE_UP} The connection is fully up from the point of
-view of the sender (now performing keep-alive)
-@item @code{KX_STATE_REKEY_SENT} The sender has initiated a rekeying
-operation; the other peer has so far failed to confirm a working
-connection using the new ephemeral key
-@end itemize
-@node Establishing a connection
-@subsubsection Establishing a connection
-Peers begin their interaction by sending a @code{EphemeralKeyMessage} to
-the other peer once the TRANSPORT service notifies the CORE service about
-the connection.
-A peer receiving an @code{EphemeralKeyMessage} with a status
-indicating that the sender does not have the receiver's ephemeral key, the
-receiver's @code{EphemeralKeyMessage} is sent in response.
-Additionally, if the receiver has not yet confirmed the authenticity of
-the sender, it also sends an (encrypted)@code{PingMessage} with a
-challenge (and the identity of the target) to the other peer. Peers
-receiving a @code{PingMessage} respond with an (encrypted)
-@code{PongMessage} which includes the challenge. Peers receiving a
-@code{PongMessage} check the challenge, and if it matches set the
-connection to @code{KX_STATE_UP}.
-@node Encryption and Decryption
-@subsubsection Encryption and Decryption
-All functions related to the key exchange and encryption/decryption of
-messages can be found in @file{gnunet-service-core_kx.c} (except for the
-cryptographic primitives, which are in @file{util/crypto*.c}).
-Given the key material from ECDHE, a Key derivation function
-(@uref{https://en.wikipedia.org/wiki/Key_derivation_function, Key derivation function})
-is used to derive two pairs of encryption and decryption keys for AES-256
-and TwoFish, as well as initialization vectors and authentication keys
-(for HMAC
-(@uref{https://en.wikipedia.org/wiki/HMAC, HMAC})).
-The HMAC is computed over the encrypted payload.
-Encrypted messages include an iv_seed and the HMAC in the header.
-Each encrypted message in the CORE service includes a sequence number and
-a timestamp in the encrypted payload. The CORE service remembers the
-largest observed sequence number and a bit-mask which represents which of
-the previous 32 sequence numbers were already used.
-Messages with sequence numbers lower than the largest observed sequence
-number minus 32 are discarded. Messages with a timestamp that is less
-than @code{REKEY_TOLERANCE} off (5 minutes) are also discarded. This of
-course means that system clocks need to be reasonably synchronized for
-peers to be able to communicate. Additionally, as the ephemeral key
-changes every 12 hours, a peer would not even be able to decrypt messages
-older than 12 hours.
-@node Type maps
-@subsubsection Type maps
-Once an encrypted connection has been established, peers begin to exchange
-type maps. Type maps are used to allow the CORE service to determine which
-(encrypted) connections should be shown to which applications. A type map
-is an array of 65536 bits representing the different types of messages
-understood by applications using the CORE service. Each CORE service
-maintains this map, simply by setting the respective bit for each message
-type supported by any of the applications using the CORE service. Note
-that bits for message types embedded in higher-level protocols (such as
-MESH) will not be included in these type maps.
-Typically, the type map of a peer will be sparse. Thus, the CORE service
-attempts to compress its type map using @code{gzip}-style compression
-("deflate") prior to transmission. However, if the compression fails to
-compact the map, the map may also be transmitted without compression
-(resulting in @code{GNUNET_MESSAGE_TYPE_CORE_COMPRESSED_TYPE_MAP} or
-@code{GNUNET_MESSAGE_TYPE_CORE_BINARY_TYPE_MAP} messages respectively).
-Upon receiving a type map, the respective CORE service notifies
-applications about the connection to the other peer if they support any
-message type indicated in the type map (or no message type at all).
-If the CORE service experience a connect or disconnect event from an
-application, it updates its type map (setting or unsetting the respective
-bits) and notifies its neighbours about the change.
-The CORE services of the neighbours then in turn generate connect and
-disconnect events for the peer that sent the type map for their respective
-applications. As CORE messages may be lost, the CORE service confirms
-receiving a type map by sending back a
-@code{GNUNET_MESSAGE_TYPE_CORE_CONFIRM_TYPE_MAP}. If such a confirmation
-(with the correct hash of the type map) is not received, the sender will
-retransmit the type map (with exponential back-off).
-@cindex CADET Subsystem
-@cindex CADET
-@cindex cadet
-@node CADET Subsystem
-@section CADET Subsystem
-The CADET subsystem in GNUnet is responsible for secure end-to-end
-communications between nodes in the GNUnet overlay network. CADET builds
-on the CORE subsystem which provides for the link-layer communication and
-then adds routing, forwarding and additional security to the connections.
-CADET offers the same cryptographic services as CORE, but on an
-end-to-end level. This is done so peers retransmitting traffic on behalf
-of other peers cannot access the payload data.
-@itemize @bullet
-@item CADET provides confidentiality with so-called perfect forward
-secrecy; we use ECDHE powered by Curve25519 for the key exchange and then
-use symmetric encryption, encrypting with both AES-256 and Twofish
-@item authentication is achieved by signing the ephemeral keys using
-Ed25519, a deterministic variant of ECDSA
-@item integrity protection (using SHA-512 to do encrypt-then-MAC, although
-only 256 bits are sent to reduce overhead)
-@item replay protection (using nonces, timestamps, challenge-response,
-message counters and ephemeral keys)
-@item liveness (keep-alive messages, timeout)
-@end itemize
-Additional to the CORE-like security benefits, CADET offers other
-properties that make it a more universal service than CORE.
-@itemize @bullet
-@item CADET can establish channels to arbitrary peers in GNUnet. If a
-peer is not immediately reachable, CADET will find a path through the
-network and ask other peers to retransmit the traffic on its behalf.
-@item CADET offers (optional) reliability mechanisms. In a reliable
-channel traffic is guaranteed to arrive complete, unchanged and in-order.
-@item CADET takes care of flow and congestion control mechanisms, not
-allowing the sender to send more traffic than the receiver or the network
-are able to process.
-@end itemize
-@menu
-* libgnunetcadet::
-@end menu
-@cindex libgnunetcadet
-@node libgnunetcadet
-@subsection libgnunetcadet
-The CADET API (defined in @file{gnunet_cadet_service.h}) is the
-messaging API used by P2P applications built using GNUnet.
-It provides applications the ability to send and receive encrypted
-messages to any peer participating in GNUnet.
-The API is heavily base on the CORE API.
-CADET delivers messages to other peers in "channels".
-A channel is a permanent connection defined by a destination peer
-(identified by its public key) and a port number.
-Internally, CADET tunnels all channels towards a destination peer
-using one session key and relays the data on multiple "connections",
-independent from the channels.
-Each channel has optional parameters, the most important being the
-reliability flag.
-Should a message get lost on TRANSPORT/CORE level, if a channel is
-created with as reliable, CADET will retransmit the lost message and
-deliver it in order to the destination application.
-@pindex GNUNET_CADET_connect
-To communicate with other peers using CADET, it is necessary to first
-connect to the service using @code{GNUNET_CADET_connect}.
-This function takes several parameters in form of callbacks, to allow the
-client to react to various events, like incoming channels or channels that
-terminate, as well as specify a list of ports the client wishes to listen
-to (at the moment it is not possible to start listening on further ports
-once connected, but nothing prevents a client to connect several times to
-CADET, even do one connection per listening port).
-The function returns a handle which has to be used for any further
-interaction with the service.
-@pindex GNUNET_CADET_channel_create
-To connect to a remote peer, a client has to call the
-@code{GNUNET_CADET_channel_create} function. The most important parameters
-given are the remote peer's identity (it public key) and a port, which
-specifies which application on the remote peer to connect to, similar to
-TCP/UDP ports. CADET will then find the peer in the GNUnet network and
-establish the proper low-level connections and do the necessary key
-exchanges to assure and authenticated, secure and verified communication.
-Similar to @code{GNUNET_CADET_connect},@code{GNUNET_CADET_create_channel}
-returns a handle to interact with the created channel.
-@pindex GNUNET_CADET_notify_transmit_ready
-For every message the client wants to send to the remote application,
-@code{GNUNET_CADET_notify_transmit_ready} must be called, indicating the
-channel on which the message should be sent and the size of the message
-(but not the message itself!). Once CADET is ready to send the message,
-the provided callback will fire, and the message contents are provided to
-this callback.
-Please note the CADET does not provide an explicit notification of when a
-channel is connected. In loosely connected networks, like big wireless
-mesh networks, this can take several seconds, even minutes in the worst
-case. To be alerted when a channel is online, a client can call
-@code{GNUNET_CADET_notify_transmit_ready} immediately after
-@code{GNUNET_CADET_create_channel}. When the callback is activated, it
-means that the channel is online. The callback can give 0 bytes to CADET
-if no message is to be sent, this is OK.
-@pindex GNUNET_CADET_notify_transmit_cancel
-If a transmission was requested but before the callback fires it is no
-longer needed, it can be canceled with
-@code{GNUNET_CADET_notify_transmit_ready_cancel}, which uses the handle
-given back by @code{GNUNET_CADET_notify_transmit_ready}.
-As in the case of CORE, only one message can be requested at a time: a
-client must not call @code{GNUNET_CADET_notify_transmit_ready} again until
-the callback is called or the request is canceled.
-@pindex GNUNET_CADET_channel_destroy
-When a channel is no longer needed, a client can call
-@code{GNUNET_CADET_channel_destroy} to get rid of it.
-Note that CADET will try to transmit all pending traffic before notifying
-the remote peer of the destruction of the channel, including
-retransmitting lost messages if the channel was reliable.
-Incoming channels, channels being closed by the remote peer, and traffic
-on any incoming or outgoing channels are given to the client when CADET
-executes the callbacks given to it at the time of
-@code{GNUNET_CADET_connect}.
-@pindex GNUNET_CADET_disconnect
-Finally, when an application no longer wants to use CADET, it should call
-@code{GNUNET_CADET_disconnect}, but first all channels and pending
-transmissions must be closed (otherwise CADET will complain).
-@cindex NSE Subsystem
-@node NSE Subsystem
-@section NSE Subsystem
-NSE stands for @dfn{Network Size Estimation}. The NSE subsystem provides
-other subsystems and users with a rough estimate of the number of peers
-currently participating in the GNUnet overlay.
-The computed value is not a precise number as producing a precise number
-in a decentralized, efficient and secure way is impossible.
-While NSE's estimate is inherently imprecise, NSE also gives the expected
-range. For a peer that has been running in a stable network for a
-while, the real network size will typically (99.7% of the time) be in the
-range of [2/3 estimate, 3/2 estimate]. We will now give an overview of the
-algorithm used to calculate the estimate;
-all of the details can be found in this technical report.
-@c FIXME: link to the report.
-@menu
-* Motivation::
-* Principle::
-* libgnunetnse::
-* The NSE Client-Service Protocol::
-* The NSE Peer-to-Peer Protocol::
-@end menu
-@node Motivation
-@subsection Motivation
-Some subsystems, like DHT, need to know the size of the GNUnet network to
-optimize some parameters of their own protocol. The decentralized nature
-of GNUnet makes efficient and securely counting the exact number of peers
-infeasible. Although there are several decentralized algorithms to count
-the number of peers in a system, so far there is none to do so securely.
-Other protocols may allow any malicious peer to manipulate the final
-result or to take advantage of the system to perform
-@dfn{Denial of Service} (DoS) attacks against the network.
-GNUnet's NSE protocol avoids these drawbacks.
-@menu
-* Security::
-@end menu
-@cindex NSE security
-@cindex nse security
-@node Security
-@subsubsection Security
-The NSE subsystem is designed to be resilient against these attacks.
-It uses @uref{http://en.wikipedia.org/wiki/Proof-of-work_system, proofs of work}
-to prevent one peer from impersonating a large number of participants,
-which would otherwise allow an adversary to artificially inflate the
-estimate.
-The DoS protection comes from the time-based nature of the protocol:
-the estimates are calculated periodically and out-of-time traffic is
-either ignored or stored for later retransmission by benign peers.
-In particular, peers cannot trigger global network communication at will.
-@cindex NSE principle
-@cindex nse principle
-@node Principle
-@subsection Principle
-The algorithm calculates the estimate by finding the globally closest
-peer ID to a random, time-based value.
-The idea is that the closer the ID is to the random value, the more
-"densely packed" the ID space is, and therefore, more peers are in the
-network.
-@menu
-* Example::
-* Algorithm::
-* Target value::
-* Timing::
-* Controlled Flooding::
-* Calculating the estimate::
-@end menu
-@node Example
-@subsubsection Example
-Suppose all peers have IDs between 0 and 100 (our ID space), and the
-random value is 42.
-If the closest peer has the ID 70 we can imagine that the average
-"distance" between peers is around 30 and therefore the are around 3
-peers in the whole ID space. On the other hand, if the closest peer has
-the ID 44, we can imagine that the space is rather packed with peers,
-maybe as much as 50 of them.
-Naturally, we could have been rather unlucky, and there is only one peer
-and happens to have the ID 44. Thus, the current estimate is calculated
-as the average over multiple rounds, and not just a single sample.
-@node Algorithm
-@subsubsection Algorithm
-Given that example, one can imagine that the job of the subsystem is to
-efficiently communicate the ID of the closest peer to the target value
-to all the other peers, who will calculate the estimate from it.
-@node Target value
-@subsubsection Target value
-The target value itself is generated by hashing the current time, rounded
-down to an agreed value. If the rounding amount is 1h (default) and the
-time is 12:34:56, the time to hash would be 12:00:00. The process is
-repeated each rounding amount (in this example would be every hour).
-Every repetition is called a round.
-@node Timing
-@subsubsection Timing
-The NSE subsystem has some timing control to avoid everybody broadcasting
-its ID all at one. Once each peer has the target random value, it
-compares its own ID to the target and calculates the hypothetical size of
-the network if that peer were to be the closest.
-Then it compares the hypothetical size with the estimate from the previous
-rounds. For each value there is an associated point in the period,
-let's call it "broadcast time". If its own hypothetical estimate
-is the same as the previous global estimate, its "broadcast time" will be
-in the middle of the round. If its bigger it will be earlier and if its
-smaller (the most likely case) it will be later. This ensures that the
-peers closest to the target value start broadcasting their ID the first.
-@node Controlled Flooding
-@subsubsection Controlled Flooding
-When a peer receives a value, first it verifies that it is closer than the
-closest value it had so far, otherwise it answers the incoming message
-with a message containing the better value. Then it checks a proof of
-work that must be included in the incoming message, to ensure that the
-other peer's ID is not made up (otherwise a malicious peer could claim to
-have an ID of exactly the target value every round). Once validated, it
-compares the broadcast time of the received value with the current time
-and if it's not too early, sends the received value to its neighbors.
-Otherwise it stores the value until the correct broadcast time comes.
-This prevents unnecessary traffic of sub-optimal values, since a better
-value can come before the broadcast time, rendering the previous one
-obsolete and saving the traffic that would have been used to broadcast it
-to the neighbors.
-@node Calculating the estimate
-@subsubsection Calculating the estimate
-Once the closest ID has been spread across the network each peer gets the
-exact distance between this ID and the target value of the round and
-calculates the estimate with a mathematical formula described in the tech
-report. The estimate generated with this method for a single round is not
-very precise. Remember the case of the example, where the only peer is the
-ID 44 and we happen to generate the target value 42, thinking there are
-50 peers in the network. Therefore, the NSE subsystem remembers the last
-64 estimates and calculates an average over them, giving a result of which
-usually has one bit of uncertainty (the real size could be half of the
-estimate or twice as much). Note that the actual network size is
-calculated in powers of two of the raw input, thus one bit of uncertainty
-means a factor of two in the size estimate.
-@cindex libgnunetnse
-@node libgnunetnse
-@subsection libgnunetnse
-The NSE subsystem has the simplest API of all services, with only two
-calls: @code{GNUNET_NSE_connect} and @code{GNUNET_NSE_disconnect}.
-The connect call gets a callback function as a parameter and this function
-is called each time the network agrees on an estimate. This usually is
-once per round, with some exceptions: if the closest peer has a late
-local clock and starts spreading its ID after everyone else agreed on a
-value, the callback might be activated twice in a round, the second value
-being always bigger than the first. The default round time is set to
-1 hour.
-The disconnect call disconnects from the NSE subsystem and the callback
-is no longer called with new estimates.
-@menu
-* Results::
-* libgnunetnse - Examples::
-@end menu
-@node Results
-@subsubsection Results
-The callback provides two values: the average and the
-@uref{http://en.wikipedia.org/wiki/Standard_deviation, standard deviation}
-of the last 64 rounds. The values provided by the callback function are
-logarithmic, this means that the real estimate numbers can be obtained by
-calculating 2 to the power of the given value (2average). From a
-statistics point of view this means that:
-@itemize @bullet
-@item 68% of the time the real size is included in the interval
-[(2average-stddev), 2]
-@item 95% of the time the real size is included in the interval
-[(2average-2*stddev, 2^average+2*stddev]
-@item 99.7% of the time the real size is included in the interval
-[(2average-3*stddev, 2average+3*stddev]
-@end itemize
-The expected standard variation for 64 rounds in a network of stable size
-is 0.2. Thus, we can say that normally:
-@itemize @bullet
-@item 68% of the time the real size is in the range [-13%, +15%]
-@item 95% of the time the real size is in the range [-24%, +32%]
-@item 99.7% of the time the real size is in the range [-34%, +52%]
-@end itemize
-As said in the introduction, we can be quite sure that usually the real
-size is between one third and three times the estimate. This can of
-course vary with network conditions.
-Thus, applications may want to also consider the provided standard
-deviation value, not only the average (in particular, if the standard
-variation is very high, the average maybe meaningless: the network size is
-changing rapidly).
-@node libgnunetnse - Examples
-@subsubsection libgnunetnse -Examples
-Let's close with a couple examples.
-@table @asis
-@item Average: 10, std dev: 1 Here the estimate would be
-2^10 = 1024 peers. (The range in which we can be 95% sure is:
-[2^8, 2^12] = [256, 4096]. We can be very (>99.7%) sure that the network
-is not a hundred peers and absolutely sure that it is not a million peers,
-but somewhere around a thousand.)
-@item Average 22, std dev: 0.2 Here the estimate would be
-2^22 = 4 Million peers. (The range in which we can be 99.7% sure
-is: [2^21.4, 2^22.6] = [2.8M, 6.3M]. We can be sure that the network size
-is around four million, with absolutely way of it being 1 million.)
-@end table
-To put this in perspective, if someone remembers the LHC Higgs boson
-results, were announced with "5 sigma" and "6 sigma" certainties. In this
-case a 5 sigma minimum would be 2 million and a 6 sigma minimum,
-1.8 million.
-@node The NSE Client-Service Protocol
-@subsection The NSE Client-Service Protocol
-As with the API, the client-service protocol is very simple, only has 2
-different messages, defined in @code{src/nse/nse.h}:
-@itemize @bullet
-@item @code{GNUNET_MESSAGE_TYPE_NSE_START}@ This message has no parameters
-and is sent from the client to the service upon connection.
-@item @code{GNUNET_MESSAGE_TYPE_NSE_ESTIMATE}@ This message is sent from
-the service to the client for every new estimate and upon connection.
-Contains a timestamp for the estimate, the average and the standard
-deviation for the respective round.
-@end itemize
-When the @code{GNUNET_NSE_disconnect} API call is executed, the client
-simply disconnects from the service, with no message involved.
-@cindex NSE Peer-to-Peer Protocol
-@node The NSE Peer-to-Peer Protocol
-@subsection The NSE Peer-to-Peer Protocol
-@pindex GNUNET_MESSAGE_TYPE_NSE_P2P_FLOOD
-The NSE subsystem only has one message in the P2P protocol, the
-@code{GNUNET_MESSAGE_TYPE_NSE_P2P_FLOOD} message.
-This message key contents are the timestamp to identify the round
-(differences in system clocks may cause some peers to send messages way
-too early or way too late, so the timestamp allows other peers to
-identify such messages easily), the
-@uref{http://en.wikipedia.org/wiki/Proof-of-work_system, proof of work}
-used to make it difficult to mount a
-@uref{http://en.wikipedia.org/wiki/Sybil_attack, Sybil attack}, and the
-public key, which is used to verify the signature on the message.
-Every peer stores a message for the previous, current and next round. The
-messages for the previous and current round are given to peers that
-connect to us. The message for the next round is simply stored until our
-system clock advances to the next round. The message for the current round
-is what we are flooding the network with right now.
-At the beginning of each round the peer does the following:
-@itemize @bullet
-@item calculates its own distance to the target value
-@item creates, signs and stores the message for the current round (unless
-it has a better message in the "next round" slot which came early in the
-previous round)
-@item calculates, based on the stored round message (own or received) when
-to start flooding it to its neighbors
-@end itemize
-Upon receiving a message the peer checks the validity of the message
-(round, proof of work, signature). The next action depends on the
-contents of the incoming message:
-@itemize @bullet
-@item if the message is worse than the current stored message, the peer
-sends the current message back immediately, to stop the other peer from
-spreading suboptimal results
-@item if the message is better than the current stored message, the peer
-stores the new message and calculates the new target time to start
-spreading it to its neighbors (excluding the one the message came from)
-@item if the message is for the previous round, it is compared to the
-message stored in the "previous round slot", which may then be updated
-@item if the message is for the next round, it is compared to the message
-stored in the "next round slot", which again may then be updated
-@end itemize
-Finally, when it comes to send the stored message for the current round to
-the neighbors there is a random delay added for each neighbor, to avoid
-traffic spikes and minimize cross-messages.
-@cindex HOSTLIST Subsystem
-@node HOSTLIST Subsystem
-@section HOSTLIST Subsystem
-Peers in the GNUnet overlay network need address information so that they
-can connect with other peers. GNUnet uses so called HELLO messages to
-store and exchange peer addresses.
-GNUnet provides several methods for peers to obtain this information:
-@itemize @bullet
-@item out-of-band exchange of HELLO messages (manually, using for example
-gnunet-peerinfo)
-@item HELLO messages shipped with GNUnet (automatic with distribution)
-@item UDP neighbor discovery in LAN (IPv4 broadcast, IPv6 multicast)
-@item topology gossiping (learning from other peers we already connected
-to), and
-@item the HOSTLIST daemon covered in this section, which is particularly
-relevant for bootstrapping new peers.
-@end itemize
-New peers have no existing connections (and thus cannot learn from gossip
-among peers), may not have other peers in their LAN and might be started
-with an outdated set of HELLO messages from the distribution.
-In this case, getting new peers to connect to the network requires either
-manual effort or the use of a HOSTLIST to obtain HELLOs.
-@menu
-* HELLOs::
-* Overview for the HOSTLIST subsystem::
-* Interacting with the HOSTLIST daemon::
-* Hostlist security address validation::
-* The HOSTLIST daemon::
-* The HOSTLIST server::
-* The HOSTLIST client::
-* Usage::
-@end menu
-@node HELLOs
-@subsection HELLOs
-The basic information peers require to connect to other peers are
-contained in so called HELLO messages you can think of as a business card.
-Besides the identity of the peer (based on the cryptographic public key) a
-HELLO message may contain address information that specifies ways to
-contact a peer. By obtaining HELLO messages, a peer can learn how to
-contact other peers.
-@node Overview for the HOSTLIST subsystem
-@subsection Overview for the HOSTLIST subsystem
-The HOSTLIST subsystem provides a way to distribute and obtain contact
-information to connect to other peers using a simple HTTP GET request.
-It's implementation is split in three parts, the main file for the daemon
-itself (@file{gnunet-daemon-hostlist.c}), the HTTP client used to download
-peer information (@file{hostlist-client.c}) and the server component used
-to provide this information to other peers (@file{hostlist-server.c}).
-The server is basically a small HTTP web server (based on GNU
-libmicrohttpd) which provides a list of HELLOs known to the local peer for
-download. The client component is basically a HTTP client
-(based on libcurl) which can download hostlists from one or more websites.
-The hostlist format is a binary blob containing a sequence of HELLO
-messages. Note that any HTTP server can theoretically serve a hostlist,
-the built-in hostlist server makes it simply convenient to offer this
-service.
-@menu
-* Features::
-* HOSTLIST - Limitations::
-@end menu
-@node Features
-@subsubsection Features
-The HOSTLIST daemon can:
-@itemize @bullet
-@item provide HELLO messages with validated addresses obtained from
-PEERINFO to download for other peers
-@item download HELLO messages and forward these message to the TRANSPORT
-subsystem for validation
-@item advertises the URL of this peer's hostlist address to other peers
-via gossip
-@item automatically learn about hostlist servers from the gossip of other
-peers
-@end itemize
-@node HOSTLIST - Limitations
-@subsubsection HOSTLIST - Limitations
-The HOSTLIST daemon does not:
-@itemize @bullet
-@item verify the cryptographic information in the HELLO messages
-@item verify the address information in the HELLO messages
-@end itemize
-@node Interacting with the HOSTLIST daemon
-@subsection Interacting with the HOSTLIST daemon
-The HOSTLIST subsystem is currently implemented as a daemon, so there is
-no need for the user to interact with it and therefore there is no
-command line tool and no API to communicate with the daemon. In the
-future, we can envision changing this to allow users to manually trigger
-the download of a hostlist.
-Since there is no command line interface to interact with HOSTLIST, the
-only way to interact with the hostlist is to use STATISTICS to obtain or
-modify information about the status of HOSTLIST:
-@example
-$ gnunet-statistics -s hostlist
-@end example
-@noindent
-In particular, HOSTLIST includes a @strong{persistent} value in statistics
-that specifies when the hostlist server might be queried next. As this
-value is exponentially increasing during runtime, developers may want to
-reset or manually adjust it. Note that HOSTLIST (but not STATISTICS) needs
-to be shutdown if changes to this value are to have any effect on the
-daemon (as HOSTLIST does not monitor STATISTICS for changes to the
-download frequency).
-@node Hostlist security address validation
-@subsection Hostlist security address validation
-Since information obtained from other parties cannot be trusted without
-validation, we have to distinguish between @emph{validated} and
-@emph{not validated} addresses. Before using (and so trusting)
-information from other parties, this information has to be double-checked
-(validated). Address validation is not done by HOSTLIST but by the
-TRANSPORT service.
-The HOSTLIST component is functionally located between the PEERINFO and
-the TRANSPORT subsystem. When acting as a server, the daemon obtains valid
-(@emph{validated}) peer information (HELLO messages) from the PEERINFO
-service and provides it to other peers. When acting as a client, it
-contacts the HOSTLIST servers specified in the configuration, downloads
-the (unvalidated) list of HELLO messages and forwards these information
-to the TRANSPORT server to validate the addresses.
-@cindex HOSTLIST daemon
-@node The HOSTLIST daemon
-@subsection The HOSTLIST daemon
-The hostlist daemon is the main component of the HOSTLIST subsystem. It is
-started by the ARM service and (if configured) starts the HOSTLIST client
-and server components.
-@pindex GNUNET_MESSAGE_TYPE_HOSTLIST_ADVERTISEMENT
-If the daemon provides a hostlist itself it can advertise it's own
-hostlist to other peers. To do so it sends a
-@code{GNUNET_MESSAGE_TYPE_HOSTLIST_ADVERTISEMENT} message to other peers
-when they connect to this peer on the CORE level. This hostlist
-advertisement message contains the URL to access the HOSTLIST HTTP
-server of the sender. The daemon may also subscribe to this type of
-message from CORE service, and then forward these kind of message to the
-HOSTLIST client. The client then uses all available URLs to download peer
-information when necessary.
-When starting, the HOSTLIST daemon first connects to the CORE subsystem
-and if hostlist learning is enabled, registers a CORE handler to receive
-this kind of messages. Next it starts (if configured) the client and
-server. It passes pointers to CORE connect and disconnect and receive
-handlers where the client and server store their functions, so the daemon
-can notify them about CORE events.
-To clean up on shutdown, the daemon has a cleaning task, shutting down all
-subsystems and disconnecting from CORE.
-@cindex HOSTLIST server
-@node The HOSTLIST server
-@subsection The HOSTLIST server
-The server provides a way for other peers to obtain HELLOs. Basically it
-is a small web server other peers can connect to and download a list of
-HELLOs using standard HTTP; it may also advertise the URL of the hostlist
-to other peers connecting on CORE level.
-@menu
-* The HTTP Server::
-* Advertising the URL::
-@end menu
-@node The HTTP Server
-@subsubsection The HTTP Server
-During startup, the server starts a web server listening on the port
-specified with the HTTPPORT value (default 8080). In addition it connects
-to the PEERINFO service to obtain peer information. The HOSTLIST server
-uses the GNUNET_PEERINFO_iterate function to request HELLO information for
-all peers and adds their information to a new hostlist if they are
-suitable (expired addresses and HELLOs without addresses are both not
-suitable) and the maximum size for a hostlist is not exceeded
-(MAX_BYTES_PER_HOSTLISTS = 500000).
-When PEERINFO finishes (with a last NULL callback), the server destroys
-the previous hostlist response available for download on the web server
-and replaces it with the updated hostlist. The hostlist format is
-basically a sequence of HELLO messages (as obtained from PEERINFO) without
-any special tokenization. Since each HELLO message contains a size field,
-the response can easily be split into separate HELLO messages by the
-client.
-A HOSTLIST client connecting to the HOSTLIST server will receive the
-hostlist as an HTTP response and the server will terminate the
-connection with the result code @code{HTTP 200 OK}.
-The connection will be closed immediately if no hostlist is available.
-@node Advertising the URL
-@subsubsection Advertising the URL
-The server also advertises the URL to download the hostlist to other peers
-if hostlist advertisement is enabled.
-When a new peer connects and has hostlist learning enabled, the server
-sends a @code{GNUNET_MESSAGE_TYPE_HOSTLIST_ADVERTISEMENT} message to this
-peer using the CORE service.
-@cindex HOSTLIST client
-@node The HOSTLIST client
-@subsection The HOSTLIST client
-The client provides the functionality to download the list of HELLOs from
-a set of URLs.
-It performs a standard HTTP request to the URLs configured and learned
-from advertisement messages received from other peers. When a HELLO is
-downloaded, the HOSTLIST client forwards the HELLO to the TRANSPORT
-service for validation.
-The client supports two modes of operation:
-@itemize @bullet
-@item download of HELLOs (bootstrapping)
-@item learning of URLs
-@end itemize
-@menu
-* Bootstrapping::
-* Learning::
-@end menu
-@node Bootstrapping
-@subsubsection Bootstrapping
-For bootstrapping, it schedules a task to download the hostlist from the
-set of known URLs.
-The downloads are only performed if the number of current
-connections is smaller than a minimum number of connections
-(at the moment 4).
-The interval between downloads increases exponentially; however, the
-exponential growth is limited if it becomes longer than an hour.
-At that point, the frequency growth is capped at
-(#number of connections * 1h).
-Once the decision has been taken to download HELLOs, the daemon chooses a
-random URL from the list of known URLs. URLs can be configured in the
-configuration or be learned from advertisement messages.
-The client uses a HTTP client library (libcurl) to initiate the download
-using the libcurl multi interface.
-Libcurl passes the data to the callback_download function which
-stores the data in a buffer if space is available and the maximum size for
-a hostlist download is not exceeded (MAX_BYTES_PER_HOSTLISTS = 500000).
-When a full HELLO was downloaded, the HOSTLIST client offers this
-HELLO message to the TRANSPORT service for validation.
-When the download is finished or failed, statistical information about the
-quality of this URL is updated.
-@cindex HOSTLIST learning
-@node Learning
-@subsubsection Learning
-The client also manages hostlist advertisements from other peers. The
-HOSTLIST daemon forwards @code{GNUNET_MESSAGE_TYPE_HOSTLIST_ADVERTISEMENT}
-messages to the client subsystem, which extracts the URL from the message.
-Next, a test of the newly obtained URL is performed by triggering a
-download from the new URL. If the URL works correctly, it is added to the
-list of working URLs.
-The size of the list of URLs is restricted, so if an additional server is
-added and the list is full, the URL with the worst quality ranking
-(determined through successful downloads and number of HELLOs e.g.) is
-discarded. During shutdown the list of URLs is saved to a file for
-persistence and loaded on startup. URLs from the configuration file are
-never discarded.
-@node Usage
-@subsection Usage
-To start HOSTLIST by default, it has to be added to the DEFAULTSERVICES
-section for the ARM services. This is done in the default configuration.
-For more information on how to configure the HOSTLIST subsystem see the
-installation handbook:@
-Configuring the hostlist to bootstrap@
-Configuring your peer to provide a hostlist
-@cindex IDENTITY Subsystem
-@node IDENTITY Subsystem
-@section IDENTITY Subsystem
-Identities of "users" in GNUnet are called egos.
-Egos can be used as pseudonyms ("fake names") or be tied to an
-organization (for example, "GNU") or even the actual identity of a human.
-GNUnet users are expected to have many egos. They might have one tied to
-their real identity, some for organizations they manage, and more for
-different domains where they want to operate under a pseudonym.
-The IDENTITY service allows users to manage their egos. The identity
-service manages the private keys egos of the local user; it does not
-manage identities of other users (public keys). Public keys for other
-users need names to become manageable. GNUnet uses the
-@dfn{GNU Name System} (GNS) to give names to other users and manage their
-public keys securely. This chapter is about the IDENTITY service,
-which is about the management of private keys.
-On the network, an ego corresponds to an ECDSA key (over Curve25519,
-using RFC 6979, as required by GNS). Thus, users can perform actions
-under a particular ego by using (signing with) a particular private key.
-Other users can then confirm that the action was really performed by that
-ego by checking the signature against the respective public key.
-The IDENTITY service allows users to associate a human-readable name with
-each ego. This way, users can use names that will remind them of the
-purpose of a particular ego.
-The IDENTITY service will store the respective private keys and
-allows applications to access key information by name.
-Users can change the name that is locally (!) associated with an ego.
-Egos can also be deleted, which means that the private key will be removed
-and it thus will not be possible to perform actions with that ego in the
-future.
-Additionally, the IDENTITY subsystem can associate service functions with
-egos.
-For example, GNS requires the ego that should be used for the shorten
-zone. GNS will ask IDENTITY for an ego for the "gns-short" service.
-The IDENTITY service has a mapping of such service strings to the name of
-the ego that the user wants to use for this service, for example
-"my-short-zone-ego".
-Finally, the IDENTITY API provides access to a special ego, the
-anonymous ego. The anonymous ego is special in that its private key is not
-really private, but fixed and known to everyone.
-Thus, anyone can perform actions as anonymous. This can be useful as with
-this trick, code does not have to contain a special case to distinguish
-between anonymous and pseudonymous egos.
-@menu
-* libgnunetidentity::
-* The IDENTITY Client-Service Protocol::
-@end menu
-@cindex libgnunetidentity
-@node libgnunetidentity
-@subsection libgnunetidentity
-@menu
-* Connecting to the service::
-* Operations on Egos::
-* The anonymous Ego::
-* Convenience API to lookup a single ego::
-* Associating egos with service functions::
-@end menu
-@node Connecting to the service
-@subsubsection Connecting to the service
-First, typical clients connect to the identity service using
-@code{GNUNET_IDENTITY_connect}. This function takes a callback as a
-parameter.
-If the given callback parameter is non-null, it will be invoked to notify
-the application about the current state of the identities in the system.
-@itemize @bullet
-@item First, it will be invoked on all known egos at the time of the
-connection. For each ego, a handle to the ego and the user's name for the
-ego will be passed to the callback. Furthermore, a @code{void **} context
-argument will be provided which gives the client the opportunity to
-associate some state with the ego.
-@item Second, the callback will be invoked with NULL for the ego, the name
-and the context. This signals that the (initial) iteration over all egos
-has completed.
-@item Then, the callback will be invoked whenever something changes about
-an ego.
-If an ego is renamed, the callback is invoked with the ego handle of the
-ego that was renamed, and the new name. If an ego is deleted, the callback
-is invoked with the ego handle and a name of NULL. In the deletion case,
-the application should also release resources stored in the context.
-@item When the application destroys the connection to the identity service
-using @code{GNUNET_IDENTITY_disconnect}, the callback is again invoked
-with the ego and a name of NULL (equivalent to deletion of the egos).
-This should again be used to clean up the per-ego context.
-@end itemize
-The ego handle passed to the callback remains valid until the callback is
-invoked with a name of NULL, so it is safe to store a reference to the
-ego's handle.
-@node Operations on Egos
-@subsubsection Operations on Egos
-Given an ego handle, the main operations are to get its associated private
-key using @code{GNUNET_IDENTITY_ego_get_private_key} or its associated
-public key using @code{GNUNET_IDENTITY_ego_get_public_key}.
-The other operations on egos are pretty straightforward.
-Using @code{GNUNET_IDENTITY_create}, an application can request the
-creation of an ego by specifying the desired name.
-The operation will fail if that name is
-already in use. Using @code{GNUNET_IDENTITY_rename} the name of an
-existing ego can be changed. Finally, egos can be deleted using
-@code{GNUNET_IDENTITY_delete}. All of these operations will trigger
-updates to the callback given to the @code{GNUNET_IDENTITY_connect}
-function of all applications that are connected with the identity service
-at the time. @code{GNUNET_IDENTITY_cancel} can be used to cancel the
-operations before the respective continuations would be called.
-It is not guaranteed that the operation will not be completed anyway,
-only the continuation will no longer be called.
-@node The anonymous Ego
-@subsubsection The anonymous Ego
-A special way to obtain an ego handle is to call
-@code{GNUNET_IDENTITY_ego_get_anonymous}, which returns an ego for the
-"anonymous" user --- anyone knows and can get the private key for this
-user, so it is suitable for operations that are supposed to be anonymous
-but require signatures (for example, to avoid a special path in the code).
-The anonymous ego is always valid and accessing it does not require a
-connection to the identity service.
-@node Convenience API to lookup a single ego
-@subsubsection Convenience API to lookup a single ego
-As applications commonly simply have to lookup a single ego, there is a
-convenience API to do just that. Use @code{GNUNET_IDENTITY_ego_lookup} to
-lookup a single ego by name. Note that this is the user's name for the
-ego, not the service function. The resulting ego will be returned via a
-callback and will only be valid during that callback. The operation can
-be canceled via @code{GNUNET_IDENTITY_ego_lookup_cancel}
-(cancellation is only legal before the callback is invoked).
-@node Associating egos with service functions
-@subsubsection Associating egos with service functions
-The @code{GNUNET_IDENTITY_set} function is used to associate a particular
-ego with a service function. The name used by the service and the ego are
-given as arguments.
-Afterwards, the service can use its name to lookup the associated ego
-using @code{GNUNET_IDENTITY_get}.
-@node The IDENTITY Client-Service Protocol
-@subsection The IDENTITY Client-Service Protocol
-A client connecting to the identity service first sends a message with
-type
-@code{GNUNET_MESSAGE_TYPE_IDENTITY_START} to the service. After that, the
-client will receive information about changes to the egos by receiving
-messages of type @code{GNUNET_MESSAGE_TYPE_IDENTITY_UPDATE}.
-Those messages contain the private key of the ego and the user's name of
-the ego (or zero bytes for the name to indicate that the ego was deleted).
-A special bit @code{end_of_list} is used to indicate the end of the
-initial iteration over the identity service's egos.
-The client can trigger changes to the egos by sending @code{CREATE},
-@code{RENAME} or @code{DELETE} messages.
-The CREATE message contains the private key and the desired name.@
-The RENAME message contains the old name and the new name.@
-The DELETE message only needs to include the name of the ego to delete.@
-The service responds to each of these messages with a @code{RESULT_CODE}
-message which indicates success or error of the operation, and possibly
-a human-readable error message.
-Finally, the client can bind the name of a service function to an ego by
-sending a @code{SET_DEFAULT} message with the name of the service function
-and the private key of the ego.
-Such bindings can then be resolved using a @code{GET_DEFAULT} message,
-which includes the name of the service function. The identity service
-will respond to a GET_DEFAULT request with a SET_DEFAULT message
-containing the respective information, or with a RESULT_CODE to
-indicate an error.
-@cindex NAMESTORE Subsystem
-@node NAMESTORE Subsystem
-@section NAMESTORE Subsystem
-The NAMESTORE subsystem provides persistent storage for local GNS zone
-information. All local GNS zone information are managed by NAMESTORE. It
-provides both the functionality to administer local GNS information (e.g.
-delete and add records) as well as to retrieve GNS information (e.g to
-list name information in a client).
-NAMESTORE does only manage the persistent storage of zone information
-belonging to the user running the service: GNS information from other
-users obtained from the DHT are stored by the NAMECACHE subsystem.
-NAMESTORE uses a plugin-based database backend to store GNS information
-with good performance. Here sqlite, MySQL and PostgreSQL are supported
-database backends.
-NAMESTORE clients interact with the IDENTITY subsystem to obtain
-cryptographic information about zones based on egos as described with the
-IDENTITY subsystem, but internally NAMESTORE refers to zones using the
-ECDSA private key.
-In addition, it collaborates with the NAMECACHE subsystem and
-stores zone information when local information are modified in the
-GNS cache to increase look-up performance for local information.
-NAMESTORE provides functionality to look-up and store records, to iterate
-over a specific or all zones and to monitor zones for changes. NAMESTORE
-functionality can be accessed using the NAMESTORE api or the NAMESTORE
-command line tool.
-@menu
-* libgnunetnamestore::
-@end menu
-@cindex libgnunetnamestore
-@node libgnunetnamestore
-@subsection libgnunetnamestore
-To interact with NAMESTORE clients first connect to the NAMESTORE service
-using the @code{GNUNET_NAMESTORE_connect} passing a configuration handle.
-As a result they obtain a NAMESTORE handle, they can use for operations,
-or NULL is returned if the connection failed.
-To disconnect from NAMESTORE, clients use
-@code{GNUNET_NAMESTORE_disconnect} and specify the handle to disconnect.
-NAMESTORE internally uses the ECDSA private key to refer to zones. These
-private keys can be obtained from the IDENTITY subsystem.
-Here @emph{egos} @emph{can be used to refer to zones or the default ego
-assigned to the GNS subsystem can be used to obtained the master zone's
-private key.}
-@menu
-* Editing Zone Information::
-* Iterating Zone Information::
-* Monitoring Zone Information::
-@end menu
-@node Editing Zone Information
-@subsubsection Editing Zone Information
-NAMESTORE provides functions to lookup records stored under a label in a
-zone and to store records under a label in a zone.
-To store (and delete) records, the client uses the
-@code{GNUNET_NAMESTORE_records_store} function and has to provide
-namestore handle to use, the private key of the zone, the label to store
-the records under, the records and number of records plus an callback
-function.
-After the operation is performed NAMESTORE will call the provided
-callback function with the result GNUNET_SYSERR on failure
-(including timeout/queue drop/failure to validate), GNUNET_NO if content
-was already there or not found GNUNET_YES (or other positive value) on
-success plus an additional error message.
-Records are deleted by using the store command with 0 records to store.
-It is important to note, that records are not merged when records exist
-with the label.
-So a client has first to retrieve records, merge with existing records
-and then store the result.
-To perform a lookup operation, the client uses the
-@code{GNUNET_NAMESTORE_records_store} function. Here it has to pass the
-namestore handle, the private key of the zone and the label. It also has
-to provide a callback function which will be called with the result of
-the lookup operation:
-the zone for the records, the label, and the records including the
-number of records included.
-A special operation is used to set the preferred nickname for a zone.
-This nickname is stored with the zone and is automatically merged with
-all labels and records stored in a zone. Here the client uses the
-@code{GNUNET_NAMESTORE_set_nick} function and passes the private key of
-the zone, the nickname as string plus a the callback with the result of
-the operation.
-@node Iterating Zone Information
-@subsubsection Iterating Zone Information
-A client can iterate over all information in a zone or all zones managed
-by NAMESTORE.
-Here a client uses the @code{GNUNET_NAMESTORE_zone_iteration_start}
-function and passes the namestore handle, the zone to iterate over and a
-callback function to call with the result.
-To iterate over all the zones, it is possible to pass NULL for the zone.
-A @code{GNUNET_NAMESTORE_ZoneIterator} handle is returned to be used to
-continue iteration.
-NAMESTORE calls the callback for every result and expects the client to
-call @code{GNUNET_NAMESTORE_zone_iterator_next} to continue to iterate or
-@code{GNUNET_NAMESTORE_zone_iterator_stop} to interrupt the iteration.
-When NAMESTORE reached the last item it will call the callback with a
-NULL value to indicate.
-@node Monitoring Zone Information
-@subsubsection Monitoring Zone Information
-Clients can also monitor zones to be notified about changes. Here the
-clients uses the @code{GNUNET_NAMESTORE_zone_monitor_start} function and
-passes the private key of the zone and and a callback function to call
-with updates for a zone.
-The client can specify to obtain zone information first by iterating over
-the zone and specify a synchronization callback to be called when the
-client and the namestore are synced.
-On an update, NAMESTORE will call the callback with the private key of the
-zone, the label and the records and their number.
-To stop monitoring, the client calls
-@code{GNUNET_NAMESTORE_zone_monitor_stop} and passes the handle obtained
-from the function to start the monitoring.
-@cindex PEERINFO Subsystem
-@node PEERINFO Subsystem
-@section PEERINFO Subsystem
-The PEERINFO subsystem is used to store verified (validated) information
-about known peers in a persistent way. It obtains these addresses for
-example from TRANSPORT service which is in charge of address validation.
-Validation means that the information in the HELLO message are checked by
-connecting to the addresses and performing a cryptographic handshake to
-authenticate the peer instance stating to be reachable with these
-addresses.
-Peerinfo does not validate the HELLO messages itself but only stores them
-and gives them to interested clients.
-As future work, we think about moving from storing just HELLO messages to
-providing a generic persistent per-peer information store.
-More and more subsystems tend to need to store per-peer information in
-persistent way.
-To not duplicate this functionality we plan to provide a PEERSTORE
-service providing this functionality.
-@menu
-* PEERINFO - Features::
-* PEERINFO - Limitations::
-* DeveloperPeer Information::
-* Startup::
-* Managing Information::
-* Obtaining Information::
-* The PEERINFO Client-Service Protocol::
-* libgnunetpeerinfo::
-@end menu
-@node PEERINFO - Features
-@subsection PEERINFO - Features
-@itemize @bullet
-@item Persistent storage
-@item Client notification mechanism on update
-@item Periodic clean up for expired information
-@item Differentiation between public and friend-only HELLO
-@end itemize
-@node PEERINFO - Limitations
-@subsection PEERINFO - Limitations
-@itemize @bullet
-@item Does not perform HELLO validation
-@end itemize
-@node DeveloperPeer Information
-@subsection DeveloperPeer Information
-The PEERINFO subsystem stores these information in the form of HELLO
-messages you can think of as business cards.
-These HELLO messages contain the public key of a peer and the addresses
-a peer can be reached under.
-The addresses include an expiration date describing how long they are
-valid. This information is updated regularly by the TRANSPORT service by
-revalidating the address.
-If an address is expired and not renewed, it can be removed from the
-HELLO message.
-Some peer do not want to have their HELLO messages distributed to other
-peers, especially when GNUnet's friend-to-friend modus is enabled.
-To prevent this undesired distribution. PEERINFO distinguishes between
-@emph{public} and @emph{friend-only} HELLO messages.
-Public HELLO messages can be freely distributed to other (possibly
-unknown) peers (for example using the hostlist, gossiping, broadcasting),
-whereas friend-only HELLO messages may not be distributed to other peers.
-Friend-only HELLO messages have an additional flag @code{friend_only} set
-internally. For public HELLO message this flag is not set.
-PEERINFO does and cannot not check if a client is allowed to obtain a
-specific HELLO type.
-The HELLO messages can be managed using the GNUnet HELLO library.
-Other GNUnet systems can obtain these information from PEERINFO and use
-it for their purposes.
-Clients are for example the HOSTLIST component providing these
-information to other peers in form of a hostlist or the TRANSPORT
-subsystem using these information to maintain connections to other peers.
-@node Startup
-@subsection Startup
-During startup the PEERINFO services loads persistent HELLOs from disk.
-First PEERINFO parses the directory configured in the HOSTS value of the
-@code{PEERINFO} configuration section to store PEERINFO information.
-For all files found in this directory valid HELLO messages are extracted.
-In addition it loads HELLO messages shipped with the GNUnet distribution.
-These HELLOs are used to simplify network bootstrapping by providing
-valid peer information with the distribution.
-The use of these HELLOs can be prevented by setting the
-@code{USE_INCLUDED_HELLOS} in the @code{PEERINFO} configuration section to
-@code{NO}. Files containing invalid information are removed.
-@node Managing Information
-@subsection Managing Information
-The PEERINFO services stores information about known PEERS and a single
-HELLO message for every peer.
-A peer does not need to have a HELLO if no information are available.
-HELLO information from different sources, for example a HELLO obtained
-from a remote HOSTLIST and a second HELLO stored on disk, are combined
-and merged into one single HELLO message per peer which will be given to
-clients. During this merge process the HELLO is immediately written to
-disk to ensure persistence.
-PEERINFO in addition periodically scans the directory where information
-are stored for empty HELLO messages with expired TRANSPORT addresses.
-This periodic task scans all files in the directory and recreates the
-HELLO messages it finds.
-Expired TRANSPORT addresses are removed from the HELLO and if the
-HELLO does not contain any valid addresses, it is discarded and removed
-from the disk.
-@node Obtaining Information
-@subsection Obtaining Information
-When a client requests information from PEERINFO, PEERINFO performs a
-lookup for the respective peer or all peers if desired and transmits this
-information to the client.
-The client can specify if friend-only HELLOs have to be included or not
-and PEERINFO filters the respective HELLO messages before transmitting
-information.
-To notify clients about changes to PEERINFO information, PEERINFO
-maintains a list of clients interested in this notifications.
-Such a notification occurs if a HELLO for a peer was updated (due to a
-merge for example) or a new peer was added.
-@node The PEERINFO Client-Service Protocol
-@subsection The PEERINFO Client-Service Protocol
-To connect and disconnect to and from the PEERINFO Service PEERINFO
-utilizes the util client/server infrastructure, so no special messages
-types are used here.
-To add information for a peer, the plain HELLO message is transmitted to
-the service without any wrapping. All pieces of information required are
-stored within the HELLO message.
-The PEERINFO service provides a message handler accepting and processing
-these HELLO messages.
-When obtaining PEERINFO information using the iterate functionality
-specific messages are used. To obtain information for all peers, a
-@code{struct ListAllPeersMessage} with message type
-@code{GNUNET_MESSAGE_TYPE_PEERINFO_GET_ALL} and a flag
-include_friend_only to indicate if friend-only HELLO messages should be
-included are transmitted. If information for a specific peer is required
-a @code{struct ListAllPeersMessage} with
-@code{GNUNET_MESSAGE_TYPE_PEERINFO_GET} containing the peer identity is
-used.
-For both variants the PEERINFO service replies for each HELLO message it
-wants to transmit with a @code{struct ListAllPeersMessage} with type
-@code{GNUNET_MESSAGE_TYPE_PEERINFO_INFO} containing the plain HELLO.
-The final message is @code{struct GNUNET_MessageHeader} with type
-@code{GNUNET_MESSAGE_TYPE_PEERINFO_INFO}. If the client receives this
-message, it can proceed with the next request if any is pending.
-@node libgnunetpeerinfo
-@subsection libgnunetpeerinfo
-The PEERINFO API consists mainly of three different functionalities:
-@itemize @bullet
-@item maintaining a connection to the service
-@item adding new information to the PEERINFO service
-@item retrieving information from the PEERINFO service
-@end itemize
-@menu
-* Connecting to the PEERINFO Service::
-* Adding Information to the PEERINFO Service::
-* Obtaining Information from the PEERINFO Service::
-@end menu
-@node Connecting to the PEERINFO Service
-@subsubsection Connecting to the PEERINFO Service
-To connect to the PEERINFO service the function
-@code{GNUNET_PEERINFO_connect} is used, taking a configuration handle as
-an argument, and to disconnect from PEERINFO the function
-@code{GNUNET_PEERINFO_disconnect}, taking the PEERINFO
-handle returned from the connect function has to be called.
-@node Adding Information to the PEERINFO Service
-@subsubsection Adding Information to the PEERINFO Service
-@code{GNUNET_PEERINFO_add_peer} adds a new peer to the PEERINFO subsystem
-storage. This function takes the PEERINFO handle as an argument, the HELLO
-message to store and a continuation with a closure to be called with the
-result of the operation.
-The @code{GNUNET_PEERINFO_add_peer} returns a handle to this operation
-allowing to cancel the operation with the respective cancel function
-@code{GNUNET_PEERINFO_add_peer_cancel}. To retrieve information from
-PEERINFO you can iterate over all information stored with PEERINFO or you
-can tell PEERINFO to notify if new peer information are available.
-@node Obtaining Information from the PEERINFO Service
-@subsubsection Obtaining Information from the PEERINFO Service
-To iterate over information in PEERINFO you use
-@code{GNUNET_PEERINFO_iterate}.
-This function expects the PEERINFO handle, a flag if HELLO messages
-intended for friend only mode should be included, a timeout how long the
-operation should take and a callback with a callback closure to be called
-for the results.
-If you want to obtain information for a specific peer, you can specify
-the peer identity, if this identity is NULL, information for all peers are
-returned. The function returns a handle to allow to cancel the operation
-using @code{GNUNET_PEERINFO_iterate_cancel}.
-To get notified when peer information changes, you can use
-@code{GNUNET_PEERINFO_notify}.
-This function expects a configuration handle and a flag if friend-only
-HELLO messages should be included. The PEERINFO service will notify you
-about every change and the callback function will be called to notify you
-about changes. The function returns a handle to cancel notifications
-with @code{GNUNET_PEERINFO_notify_cancel}.
-@cindex PEERSTORE Subsystem
-@node PEERSTORE Subsystem
-@section PEERSTORE Subsystem
-GNUnet's PEERSTORE subsystem offers persistent per-peer storage for other
-GNUnet subsystems. GNUnet subsystems can use PEERSTORE to persistently
-store and retrieve arbitrary data.
-Each data record stored with PEERSTORE contains the following fields:
-@itemize @bullet
-@item subsystem: Name of the subsystem responsible for the record.
-@item peerid: Identity of the peer this record is related to.
-@item key: a key string identifying the record.
-@item value: binary record value.
-@item expiry: record expiry date.
-@end itemize
-@menu
-* Functionality::
-* Architecture::
-* libgnunetpeerstore::
-@end menu
-@node Functionality
-@subsection Functionality
-Subsystems can store any type of value under a (subsystem, peerid, key)
-combination. A "replace" flag set during store operations forces the
-PEERSTORE to replace any old values stored under the same
-(subsystem, peerid, key) combination with the new value.
-Additionally, an expiry date is set after which the record is *possibly*
-deleted by PEERSTORE.
-Subsystems can iterate over all values stored under any of the following
-combination of fields:
-@itemize @bullet
-@item (subsystem)
-@item (subsystem, peerid)
-@item (subsystem, key)
-@item (subsystem, peerid, key)
-@end itemize
-Subsystems can also request to be notified about any new values stored
-under a (subsystem, peerid, key) combination by sending a "watch"
-request to PEERSTORE.
-@node Architecture
-@subsection Architecture
-PEERSTORE implements the following components:
-@itemize @bullet
-@item PEERSTORE service: Handles store, iterate and watch operations.
-@item PEERSTORE API: API to be used by other subsystems to communicate and
-issue commands to the PEERSTORE service.
-@item PEERSTORE plugins: Handles the persistent storage. At the moment,
-only an "sqlite" plugin is implemented.
-@end itemize
-@cindex libgnunetpeerstore
-@node libgnunetpeerstore
-@subsection libgnunetpeerstore
-libgnunetpeerstore is the library containing the PEERSTORE API. Subsystems
-wishing to communicate with the PEERSTORE service use this API to open a
-connection to PEERSTORE. This is done by calling
-@code{GNUNET_PEERSTORE_connect} which returns a handle to the newly
-created connection.
-This handle has to be used with any further calls to the API.
-To store a new record, the function @code{GNUNET_PEERSTORE_store} is to
-be used which requires the record fields and a continuation function that
-will be called by the API after the STORE request is sent to the
-PEERSTORE service.
-Note that calling the continuation function does not mean that the record
-is successfully stored, only that the STORE request has been successfully
-sent to the PEERSTORE service.
-@code{GNUNET_PEERSTORE_store_cancel} can be called to cancel the STORE
-request only before the continuation function has been called.
-To iterate over stored records, the function
-@code{GNUNET_PEERSTORE_iterate} is
-to be used. @emph{peerid} and @emph{key} can be set to NULL. An iterator
-callback function will be called with each matching record found and a
-NULL record at the end to signal the end of result set.
-@code{GNUNET_PEERSTORE_iterate_cancel} can be used to cancel the ITERATE
-request before the iterator callback is called with a NULL record.
-To be notified with new values stored under a (subsystem, peerid, key)
-combination, the function @code{GNUNET_PEERSTORE_watch} is to be used.
-This will register the watcher with the PEERSTORE service, any new
-records matching the given combination will trigger the callback
-function passed to @code{GNUNET_PEERSTORE_watch}. This continues until
-@code{GNUNET_PEERSTORE_watch_cancel} is called or the connection to the
-service is destroyed.
-After the connection is no longer needed, the function
-@code{GNUNET_PEERSTORE_disconnect} can be called to disconnect from the
-PEERSTORE service.
-Any pending ITERATE or WATCH requests will be destroyed.
-If the @code{sync_first} flag is set to @code{GNUNET_YES}, the API will
-delay the disconnection until all pending STORE requests are sent to
-the PEERSTORE service, otherwise, the pending STORE requests will be
-destroyed as well.
-@cindex SET Subsystem
-@node SET Subsystem
-@section SET Subsystem
-The SET subsystem is in process of being replaced by the SETU and
-SETI subsystems, which provide basically the same functionality,
-just using two different subsystems.  SETI and SETU should be used
-for new code.
-The SET service implements efficient set operations between two peers
-over a CADET tunnel.
-Currently, set union and set intersection are the only supported
-operations. Elements of a set consist of an @emph{element type} and
-arbitrary binary @emph{data}.
-The size of an element's data is limited to around 62 KB.
-@menu
-* Local Sets::
-* Set Modifications::
-* Set Operations::
-* Result Elements::
-* libgnunetset::
-* The SET Client-Service Protocol::
-* The SET Intersection Peer-to-Peer Protocol::
-* The SET Union Peer-to-Peer Protocol::
-@end menu
-@node Local Sets
-@subsection Local Sets
-Sets created by a local client can be modified and reused for multiple
-operations. As each set operation requires potentially expensive special
-auxiliary data to be computed for each element of a set, a set can only
-participate in one type of set operation (either union or intersection).
-The type of a set is determined upon its creation.
-If a the elements of a set are needed for an operation of a different
-type, all of the set's element must be copied to a new set of appropriate
-type.
-@node Set Modifications
-@subsection Set Modifications
-Even when set operations are active, one can add to and remove elements
-from a set.
-However, these changes will only be visible to operations that have been
-created after the changes have taken place. That is, every set operation
-only sees a snapshot of the set from the time the operation was started.
-This mechanism is @emph{not} implemented by copying the whole set, but by
-attaching @emph{generation information} to each element and operation.
-@node Set Operations
-@subsection Set Operations
-Set operations can be started in two ways: Either by accepting an
-operation request from a remote peer, or by requesting a set operation
-from a remote peer.
-Set operations are uniquely identified by the involved @emph{peers}, an
-@emph{application id} and the @emph{operation type}.
-The client is notified of incoming set operations by @emph{set listeners}.
-A set listener listens for incoming operations of a specific operation
-type and application id.
-Once notified of an incoming set request, the client can accept the set
-request (providing a local set for the operation) or reject it.
-@node Result Elements
-@subsection Result Elements
-The SET service has three @emph{result modes} that determine how an
-operation's result set is delivered to the client:
-@itemize @bullet
-@item @strong{Full Result Set.} All elements of set resulting from the set
-operation are returned to the client.
-@item @strong{Added Elements.} Only elements that result from the
-operation and are not already in the local peer's set are returned.
-Note that for some operations (like set intersection) this result mode
-will never return any elements.
-This can be useful if only the remove peer is actually interested in
-the result of the set operation.
-@item @strong{Removed Elements.} Only elements that are in the local
-peer's initial set but not in the operation's result set are returned.
-Note that for some operations (like set union) this result mode will
-never return any elements. This can be useful if only the remove peer is
-actually interested in the result of the set operation.
-@end itemize
-@cindex libgnunetset
-@node libgnunetset
-@subsection libgnunetset
-@menu
-* Sets::
-* Listeners::
-* Operations::
-* Supplying a Set::
-* The Result Callback::
-@end menu
-@node Sets
-@subsubsection Sets
-New sets are created with @code{GNUNET_SET_create}. Both the local peer's
-configuration (as each set has its own client connection) and the
-operation type must be specified.
-The set exists until either the client calls @code{GNUNET_SET_destroy} or
-the client's connection to the service is disrupted.
-In the latter case, the client is notified by the return value of
-functions dealing with sets. This return value must always be checked.
-Elements are added and removed with @code{GNUNET_SET_add_element} and
-@code{GNUNET_SET_remove_element}.
-@node Listeners
-@subsubsection Listeners
-Listeners are created with @code{GNUNET_SET_listen}. Each time time a
-remote peer suggests a set operation with an application id and operation
-type matching a listener, the listener's callback is invoked.
-The client then must synchronously call either @code{GNUNET_SET_accept}
-or @code{GNUNET_SET_reject}. Note that the operation will not be started
-until the client calls @code{GNUNET_SET_commit}
-(see Section "Supplying a Set").
-@node Operations
-@subsubsection Operations
-Operations to be initiated by the local peer are created with
-@code{GNUNET_SET_prepare}. Note that the operation will not be started
-until the client calls @code{GNUNET_SET_commit}
-(see Section "Supplying a Set").
-@node Supplying a Set
-@subsubsection Supplying a Set
-To create symmetry between the two ways of starting a set operation
-(accepting and initiating it), the operation handles returned by
-@code{GNUNET_SET_accept} and @code{GNUNET_SET_prepare} do not yet have a
-set to operate on, thus they can not do any work yet.
-The client must call @code{GNUNET_SET_commit} to specify a set to use for
-an operation. @code{GNUNET_SET_commit} may only be called once per set
-operation.
-@node The Result Callback
-@subsubsection The Result Callback
-Clients must specify both a result mode and a result callback with
-@code{GNUNET_SET_accept} and @code{GNUNET_SET_prepare}. The result
-callback with a status indicating either that an element was received, or
-the operation failed or succeeded.
-The interpretation of the received element depends on the result mode.
-The callback needs to know which result mode it is used in, as the
-arguments do not indicate if an element is part of the full result set,
-or if it is in the difference between the original set and the final set.
-@node The SET Client-Service Protocol
-@subsection The SET Client-Service Protocol
-@menu
-* Creating Sets::
-* Listeners2::
-* Initiating Operations::
-* Modifying Sets::
-* Results and Operation Status::
-* Iterating Sets::
-@end menu
-@node Creating Sets
-@subsubsection Creating Sets
-For each set of a client, there exists a client connection to the service.
-Sets are created by sending the @code{GNUNET_SERVICE_SET_CREATE} message
-over a new client connection. Multiple operations for one set are
-multiplexed over one client connection, using a request id supplied by
-the client.
-@node Listeners2
-@subsubsection Listeners2
-Each listener also requires a separate client connection. By sending the
-@code{GNUNET_SERVICE_SET_LISTEN} message, the client notifies the service
-of the application id and operation type it is interested in. A client
-rejects an incoming request by sending @code{GNUNET_SERVICE_SET_REJECT}
-on the listener's client connection.
-In contrast, when accepting an incoming request, a
-@code{GNUNET_SERVICE_SET_ACCEPT} message must be sent over the@ set that
-is supplied for the set operation.
-@node Initiating Operations
-@subsubsection Initiating Operations
-Operations with remote peers are initiated by sending a
-@code{GNUNET_SERVICE_SET_EVALUATE} message to the service. The@ client
-connection that this message is sent by determines the set to use.
-@node Modifying Sets
-@subsubsection Modifying Sets
-Sets are modified with the @code{GNUNET_SERVICE_SET_ADD} and
-@code{GNUNET_SERVICE_SET_REMOVE} messages.
-@c %@menu
-@c %* Results and Operation Status::
-@c %* Iterating Sets::
-@c %@end menu
-@node Results and Operation Status
-@subsubsection Results and Operation Status
-The service notifies the client of result elements and success/failure of
-a set operation with the @code{GNUNET_SERVICE_SET_RESULT} message.
-@node Iterating Sets
-@subsubsection Iterating Sets
-All elements of a set can be requested by sending
-@code{GNUNET_SERVICE_SET_ITER_REQUEST}. The server responds with
-@code{GNUNET_SERVICE_SET_ITER_ELEMENT} and eventually terminates the
-iteration with @code{GNUNET_SERVICE_SET_ITER_DONE}.
-After each received element, the client
-must send @code{GNUNET_SERVICE_SET_ITER_ACK}. Note that only one set
-iteration may be active for a set at any given time.
-@node The SET Intersection Peer-to-Peer Protocol
-@subsection The SET Intersection Peer-to-Peer Protocol
-The intersection protocol operates over CADET and starts with a
-GNUNET_MESSAGE_TYPE_SET_P2P_OPERATION_REQUEST being sent by the peer
-initiating the operation to the peer listening for inbound requests.
-It includes the number of elements of the initiating peer, which is used
-to decide which side will send a Bloom filter first.
-The listening peer checks if the operation type and application
-identifier are acceptable for its current state.
-If not, it responds with a GNUNET_MESSAGE_TYPE_SET_RESULT and a status of
-GNUNET_SET_STATUS_FAILURE (and terminates the CADET channel).
-If the application accepts the request, the listener sends back a
-@code{GNUNET_MESSAGE_TYPE_SET_INTERSECTION_P2P_ELEMENT_INFO} if it has
-more elements in the set than the client.
-Otherwise, it immediately starts with the Bloom filter exchange.
-If the initiator receives a
-@code{GNUNET_MESSAGE_TYPE_SET_INTERSECTION_P2P_ELEMENT_INFO} response,
-it beings the Bloom filter exchange, unless the set size is indicated to
-be zero, in which case the intersection is considered finished after
-just the initial handshake.
-@menu
-* The Bloom filter exchange::
-* Salt::
-@end menu
-@node The Bloom filter exchange
-@subsubsection The Bloom filter exchange
-In this phase, each peer transmits a Bloom filter over the remaining
-keys of the local set to the other peer using a
-@code{GNUNET_MESSAGE_TYPE_SET_INTERSECTION_P2P_BF} message. This
-message additionally includes the number of elements left in the sender's
-set, as well as the XOR over all of the keys in that set.
-The number of bits 'k' set per element in the Bloom filter is calculated
-based on the relative size of the two sets.
-Furthermore, the size of the Bloom filter is calculated based on 'k' and
-the number of elements in the set to maximize the amount of data filtered
-per byte transmitted on the wire (while avoiding an excessively high
-number of iterations).
-The receiver of the message removes all elements from its local set that
-do not pass the Bloom filter test.
-It then checks if the set size of the sender and the XOR over the keys
-match what is left of its own set. If they do, it sends a
-@code{GNUNET_MESSAGE_TYPE_SET_INTERSECTION_P2P_DONE} back to indicate
-that the latest set is the final result.
-Otherwise, the receiver starts another Bloom filter exchange, except
-this time as the sender.
-@node Salt
-@subsubsection Salt
-Bloomfilter operations are probabilistic: With some non-zero probability
-the test may incorrectly say an element is in the set, even though it is
-not.
-To mitigate this problem, the intersection protocol iterates exchanging
-Bloom filters using a different random 32-bit salt in each iteration (the
-salt is also included in the message).
-With different salts, set operations may fail for different elements.
-Merging the results from the executions, the probability of failure drops
-to zero.
-The iterations terminate once both peers have established that they have
-sets of the same size, and where the XOR over all keys computes the same
-512-bit value (leaving a failure probability of 2-511).
-@node The SET Union Peer-to-Peer Protocol
-@subsection The SET Union Peer-to-Peer Protocol
-The SET union protocol is based on Eppstein's efficient set reconciliation
-without prior context. You should read this paper first if you want to
-understand the protocol.
-The union protocol operates over CADET and starts with a
-GNUNET_MESSAGE_TYPE_SET_P2P_OPERATION_REQUEST being sent by the peer
-initiating the operation to the peer listening for inbound requests.
-It includes the number of elements of the initiating peer, which is
-currently not used.
-The listening peer checks if the operation type and application
-identifier are acceptable for its current state. If not, it responds with
-a @code{GNUNET_MESSAGE_TYPE_SET_RESULT} and a status of
-@code{GNUNET_SET_STATUS_FAILURE} (and terminates the CADET channel).
-If the application accepts the request, it sends back a strata estimator
-using a message of type GNUNET_MESSAGE_TYPE_SET_UNION_P2P_SE. The
-initiator evaluates the strata estimator and initiates the exchange of
-invertible Bloom filters, sending a GNUNET_MESSAGE_TYPE_SET_UNION_P2P_IBF.
-During the IBF exchange, if the receiver cannot invert the Bloom filter or
-detects a cycle, it sends a larger IBF in response (up to a defined
-maximum limit; if that limit is reached, the operation fails).
-Elements decoded while processing the IBF are transmitted to the other
-peer using GNUNET_MESSAGE_TYPE_SET_P2P_ELEMENTS, or requested from the
-other peer using GNUNET_MESSAGE_TYPE_SET_P2P_ELEMENT_REQUESTS messages,
-depending on the sign observed during decoding of the IBF.
-Peers respond to a GNUNET_MESSAGE_TYPE_SET_P2P_ELEMENT_REQUESTS message
-with the respective element in a GNUNET_MESSAGE_TYPE_SET_P2P_ELEMENTS
-message. If the IBF fully decodes, the peer responds with a
-GNUNET_MESSAGE_TYPE_SET_UNION_P2P_DONE message instead of another
-GNUNET_MESSAGE_TYPE_SET_UNION_P2P_IBF.
-All Bloom filter operations use a salt to mingle keys before hashing them
-into buckets, such that future iterations have a fresh chance of
-succeeding if they failed due to collisions before.
-@cindex SETI Subsystem
-@node SETI Subsystem
-@section SETI Subsystem
-The SET service implements efficient set intersection between two peers
-over a CADET tunnel.
-Elements of a set consist of an @emph{element type} and
-arbitrary binary @emph{data}.
-The size of an element's data is limited to around 62 KB.
-@menu
-* Intersection Sets::
-* Set Intersection Modifications::
-* Set Intersection Operations::
-* Intersection Result Elements::
-* libgnunetseti::
-* The SETI Client-Service Protocol::
-* The SETI Intersection Peer-to-Peer Protocol::
-@end menu
-@node Intersection Sets
-@subsection Intersection Sets
-Sets created by a local client can be modified (by adding additional elements)
-and reused for multiple operations.  If elements are to be removed, a fresh
-set must be created by the client.
-@node Set Intersection Modifications
-@subsection Set Intersection Modifications
-Even when set operations are active, one can add elements
-to a set.
-However, these changes will only be visible to operations that have been
-created after the changes have taken place. That is, every set operation
-only sees a snapshot of the set from the time the operation was started.
-This mechanism is @emph{not} implemented by copying the whole set, but by
-attaching @emph{generation information} to each element and operation.
-@node Set Intersection Operations
-@subsection Set Intersection Operations
-Set operations can be started in two ways: Either by accepting an
-operation request from a remote peer, or by requesting a set operation
-from a remote peer.
-Set operations are uniquely identified by the involved @emph{peers}, an
-@emph{application id} and the @emph{operation type}.
-The client is notified of incoming set operations by @emph{set listeners}.
-A set listener listens for incoming operations of a specific operation
-type and application id.
-Once notified of an incoming set request, the client can accept the set
-request (providing a local set for the operation) or reject it.
-@node Intersection Result Elements
-@subsection Intersection Result Elements
-The SET service has two @emph{result modes} that determine how an
-operation's result set is delivered to the client:
-@itemize @bullet
-@item @strong{Return intersection.} All elements of set resulting from the set
-intersection are returned to the client.
-@item @strong{Removed Elements.} Only elements that are in the local
-peer's initial set but not in the intersection are returned.
-@end itemize
-@cindex libgnunetseti
-@node libgnunetseti
-@subsection libgnunetseti
-@menu
-* Intersection Set API::
-* Intersection Listeners::
-* Intersection Operations::
-* Supplying a Set for Intersection::
-* The Intersection Result Callback::
-@end menu
-@node Intersection Set API
-@subsubsection Intersection Set API
-New sets are created with @code{GNUNET_SETI_create}. Only the local peer's
-configuration (as each set has its own client connection) must be provided.
-The set exists until either the client calls @code{GNUNET_SET_destroy} or
-the client's connection to the service is disrupted.
-In the latter case, the client is notified by the return value of
-functions dealing with sets. This return value must always be checked.
-Elements are added with @code{GNUNET_SET_add_element}.
-@node Intersection Listeners
-@subsubsection Intersection Listeners
-Listeners are created with @code{GNUNET_SET_listen}. Each time time a
-remote peer suggests a set operation with an application id and operation
-type matching a listener, the listener's callback is invoked.
-The client then must synchronously call either @code{GNUNET_SET_accept}
-or @code{GNUNET_SET_reject}. Note that the operation will not be started
-until the client calls @code{GNUNET_SET_commit}
-(see Section "Supplying a Set").
-@node Intersection Operations
-@subsubsection Intersection Operations
-Operations to be initiated by the local peer are created with
-@code{GNUNET_SET_prepare}. Note that the operation will not be started
-until the client calls @code{GNUNET_SET_commit}
-(see Section "Supplying a Set").
-@node Supplying a Set for  Intersection
-@subsubsection Supplying a Set for Intersection
-To create symmetry between the two ways of starting a set operation
-(accepting and initiating it), the operation handles returned by
-@code{GNUNET_SET_accept} and @code{GNUNET_SET_prepare} do not yet have a
-set to operate on, thus they can not do any work yet.
-The client must call @code{GNUNET_SET_commit} to specify a set to use for
-an operation. @code{GNUNET_SET_commit} may only be called once per set
-operation.
-@node The Intersection Result Callback
-@subsubsection The Intersection Result Callback
-Clients must specify both a result mode and a result callback with
-@code{GNUNET_SET_accept} and @code{GNUNET_SET_prepare}. The result
-callback with a status indicating either that an element was received, or
-the operation failed or succeeded.
-The interpretation of the received element depends on the result mode.
-The callback needs to know which result mode it is used in, as the
-arguments do not indicate if an element is part of the full result set,
-or if it is in the difference between the original set and the final set.
-@node The SETI Client-Service Protocol
-@subsection The SETI Client-Service Protocol
-@menu
-* Creating Intersection Sets::
-* Listeners for Intersection::
-* Initiating Intersection Operations::
-* Modifying Intersection Sets::
-* Intersection Results and Operation Status::
-@end menu
-@node Creating Intersection Sets
-@subsubsection Creating Intersection Sets
-For each set of a client, there exists a client connection to the service.
-Sets are created by sending the @code{GNUNET_SERVICE_SETI_CREATE} message
-over a new client connection. Multiple operations for one set are
-multiplexed over one client connection, using a request id supplied by
-the client.
-@node Listeners for Intersection
-@subsubsection Listeners for Intersection
-Each listener also requires a separate client connection. By sending the
-@code{GNUNET_SERVICE_SETI_LISTEN} message, the client notifies the service
-of the application id and operation type it is interested in. A client
-rejects an incoming request by sending @code{GNUNET_SERVICE_SETI_REJECT}
-on the listener's client connection.
-In contrast, when accepting an incoming request, a
-@code{GNUNET_SERVICE_SETI_ACCEPT} message must be sent over the@ set that
-is supplied for the set operation.
-@node Initiating Intersection Operations
-@subsubsection Initiating Intersection Operations
-Operations with remote peers are initiated by sending a
-@code{GNUNET_SERVICE_SETI_EVALUATE} message to the service. The@ client
-connection that this message is sent by determines the set to use.
-@node Modifying Intersection Sets
-@subsubsection Modifying Intersection Sets
-Sets are modified with the @code{GNUNET_SERVICE_SETI_ADD} message.
-@c %@menu
-@c %* Results and Operation Status::
-@c %* Iterating Sets::
-@c %@end menu
-@node Intersection Results and Operation Status
-@subsubsection Intersection Results and Operation Status
-The service notifies the client of result elements and success/failure of
-a set operation with the @code{GNUNET_SERVICE_SETI_RESULT} message.
-@node The SETI Intersection Peer-to-Peer Protocol
-@subsection The SETI Intersection Peer-to-Peer Protocol
-The intersection protocol operates over CADET and starts with a
-GNUNET_MESSAGE_TYPE_SETI_P2P_OPERATION_REQUEST being sent by the peer
-initiating the operation to the peer listening for inbound requests.
-It includes the number of elements of the initiating peer, which is used
-to decide which side will send a Bloom filter first.
-The listening peer checks if the operation type and application
-identifier are acceptable for its current state.
-If not, it responds with a GNUNET_MESSAGE_TYPE_SETI_RESULT and a status of
-GNUNET_SETI_STATUS_FAILURE (and terminates the CADET channel).
-If the application accepts the request, the listener sends back a
-@code{GNUNET_MESSAGE_TYPE_SETI_P2P_ELEMENT_INFO} if it has
-more elements in the set than the client.
-Otherwise, it immediately starts with the Bloom filter exchange.
-If the initiator receives a
-@code{GNUNET_MESSAGE_TYPE_SETI_P2P_ELEMENT_INFO} response,
-it beings the Bloom filter exchange, unless the set size is indicated to
-be zero, in which case the intersection is considered finished after
-just the initial handshake.
-@menu
-* The Bloom filter exchange in SETI::
-* Intersection Salt::
-@end menu
-@node The Bloom filter exchange in SETI
-@subsubsection The Bloom filter exchange in SETI
-In this phase, each peer transmits a Bloom filter over the remaining
-keys of the local set to the other peer using a
-@code{GNUNET_MESSAGE_TYPE_SETI_P2P_BF} message. This
-message additionally includes the number of elements left in the sender's
-set, as well as the XOR over all of the keys in that set.
-The number of bits 'k' set per element in the Bloom filter is calculated
-based on the relative size of the two sets.
-Furthermore, the size of the Bloom filter is calculated based on 'k' and
-the number of elements in the set to maximize the amount of data filtered
-per byte transmitted on the wire (while avoiding an excessively high
-number of iterations).
-The receiver of the message removes all elements from its local set that
-do not pass the Bloom filter test.
-It then checks if the set size of the sender and the XOR over the keys
-match what is left of its own set. If they do, it sends a
-@code{GNUNET_MESSAGE_TYPE_SETI_P2P_DONE} back to indicate
-that the latest set is the final result.
-Otherwise, the receiver starts another Bloom filter exchange, except
-this time as the sender.
-@node Intersection Salt
-@subsubsection Intersection Salt
-Bloom filter operations are probabilistic: With some non-zero probability
-the test may incorrectly say an element is in the set, even though it is
-not.
-To mitigate this problem, the intersection protocol iterates exchanging
-Bloom filters using a different random 32-bit salt in each iteration (the
-salt is also included in the message).
-With different salts, set operations may fail for different elements.
-Merging the results from the executions, the probability of failure drops
-to zero.
-The iterations terminate once both peers have established that they have
-sets of the same size, and where the XOR over all keys computes the same
-512-bit value (leaving a failure probability of 2-511).
-@cindex SETU Subsystem
-@node SETU Subsystem
-@section SETU Subsystem
-The SETU service implements efficient set union operations between two peers
-over a CADET tunnel.  Elements of a set consist of an @emph{element type} and
-arbitrary binary @emph{data}.  The size of an element's data is limited to
-around 62 KB.
-@menu
-* Union Sets::
-* Set Union Modifications::
-* Set Union Operations::
-* Union Result Elements::
-* libgnunetsetu::
-* The SETU Client-Service Protocol::
-* The SETU Union Peer-to-Peer Protocol::
-@end menu
-@node Union Sets
-@subsection Union Sets
-Sets created by a local client can be modified (by adding additional elements)
-and reused for multiple operations.  If elements are to be removed, a fresh
-set must be created by the client.
-@node Set Union Modifications
-@subsection Set Union Modifications
-Even when set operations are active, one can add elements
-to a set.
-However, these changes will only be visible to operations that have been
-created after the changes have taken place. That is, every set operation
-only sees a snapshot of the set from the time the operation was started.
-This mechanism is @emph{not} implemented by copying the whole set, but by
-attaching @emph{generation information} to each element and operation.
-@node Set Union Operations
-@subsection Set Union Operations
-Set operations can be started in two ways: Either by accepting an
-operation request from a remote peer, or by requesting a set operation
-from a remote peer.
-Set operations are uniquely identified by the involved @emph{peers}, an
-@emph{application id} and the @emph{operation type}.
-The client is notified of incoming set operations by @emph{set listeners}.
-A set listener listens for incoming operations of a specific operation
-type and application id.
-Once notified of an incoming set request, the client can accept the set
-request (providing a local set for the operation) or reject it.
-@node Union Result Elements
-@subsection Union Result Elements
-The SET service has three @emph{result modes} that determine how an
-operation's result set is delivered to the client:
-@itemize @bullet
-@item @strong{Locally added Elements.} Elements that are in the union
-but not already in the local peer's set are returned.
-@item @strong{Remote added Elements.} Additionally, notify the client
-if the remote peer lacked some elements and thus also return to the
-local client those elements that we are sending to the remote peer to
-be added to its union.  Obtaining these elements requires setting
-the @code{GNUNET_SETU_OPTION_SYMMETRIC} option.
-@end itemize
-@cindex libgnunetsetu
-@node libgnunetsetu
-@subsection libgnunetsetu
-@menu
-* Union Set API::
-* Union Listeners::
-* Union Operations::
-* Supplying a Set for Union::
-* The Union Result Callback::
-@end menu
-@node Union Set API
-@subsubsection Union Set API
-New sets are created with @code{GNUNET_SETU_create}. Only the local peer's
-configuration (as each set has its own client connection) must be provided.
-The set exists until either the client calls @code{GNUNET_SETU_destroy} or
-the client's connection to the service is disrupted.
-In the latter case, the client is notified by the return value of
-functions dealing with sets. This return value must always be checked.
-Elements are added with @code{GNUNET_SETU_add_element}.
-@node Union Listeners
-@subsubsection Union Listeners
-Listeners are created with @code{GNUNET_SETU_listen}. Each time time a
-remote peer suggests a set operation with an application id and operation
-type matching a listener, the listener's callback is invoked.
-The client then must synchronously call either @code{GNUNET_SETU_accept}
-or @code{GNUNET_SETU_reject}. Note that the operation will not be started
-until the client calls @code{GNUNET_SETU_commit}
-(see Section "Supplying a Set").
-@node Union Operations
-@subsubsection Union Operations
-Operations to be initiated by the local peer are created with
-@code{GNUNET_SETU_prepare}. Note that the operation will not be started
-until the client calls @code{GNUNET_SETU_commit}
-(see Section "Supplying a Set").
-@node Supplying a Set for Union
-@subsubsection Supplying a Set for Union
-To create symmetry between the two ways of starting a set operation
-(accepting and initiating it), the operation handles returned by
-@code{GNUNET_SETU_accept} and @code{GNUNET_SETU_prepare} do not yet have a
-set to operate on, thus they can not do any work yet.
-The client must call @code{GNUNET_SETU_commit} to specify a set to use for
-an operation. @code{GNUNET_SETU_commit} may only be called once per set
-operation.
-@node The Union Result Callback
-@subsubsection The Union Result Callback
-Clients must specify both a result mode and a result callback with
-@code{GNUNET_SETU_accept} and @code{GNUNET_SETU_prepare}. The result
-callback with a status indicating either that an element was received,
-transmitted to the other peer (if this information was requested), or
-if the operation failed or ultimately succeeded.
-@node The SETU Client-Service Protocol
-@subsection The SETU Client-Service Protocol
-@menu
-* Creating Union Sets::
-* Listeners for Union::
-* Initiating Union Operations::
-* Modifying Union Sets::
-* Union Results and Operation Status::
-@end menu
-@node Creating Union Sets
-@subsubsection Creating Union Sets
-For each set of a client, there exists a client connection to the service.
-Sets are created by sending the @code{GNUNET_SERVICE_SETU_CREATE} message
-over a new client connection. Multiple operations for one set are
-multiplexed over one client connection, using a request id supplied by
-the client.
-@node Listeners for Union
-@subsubsection Listeners for Union
-Each listener also requires a separate client connection. By sending the
-@code{GNUNET_SERVICE_SETU_LISTEN} message, the client notifies the service
-of the application id and operation type it is interested in. A client
-rejects an incoming request by sending @code{GNUNET_SERVICE_SETU_REJECT}
-on the listener's client connection.
-In contrast, when accepting an incoming request, a
-@code{GNUNET_SERVICE_SETU_ACCEPT} message must be sent over the@ set that
-is supplied for the set operation.
-@node Initiating Union Operations
-@subsubsection Initiating Union Operations
-Operations with remote peers are initiated by sending a
-@code{GNUNET_SERVICE_SETU_EVALUATE} message to the service. The@ client
-connection that this message is sent by determines the set to use.
-@node Modifying Union Sets
-@subsubsection Modifying Union Sets
-Sets are modified with the @code{GNUNET_SERVICE_SETU_ADD} message.
-@c %@menu
-@c %* Results and Operation Status::
-@c %* Iterating Sets::
-@c %@end menu
-@node Union Results and Operation Status
-@subsubsection Union Results and Operation Status
-The service notifies the client of result elements and success/failure of
-a set operation with the @code{GNUNET_SERVICE_SETU_RESULT} message.
-@node The SETU Union Peer-to-Peer Protocol
-@subsection The SETU Union Peer-to-Peer Protocol
-The SET union protocol is based on Eppstein's efficient set reconciliation
-without prior context. You should read this paper first if you want to
-understand the protocol.
-The union protocol operates over CADET and starts with a
-GNUNET_MESSAGE_TYPE_SETU_P2P_OPERATION_REQUEST being sent by the peer
-initiating the operation to the peer listening for inbound requests.
-It includes the number of elements of the initiating peer, which is
-currently not used.
-The listening peer checks if the operation type and application
-identifier are acceptable for its current state. If not, it responds with
-a @code{GNUNET_MESSAGE_TYPE_SETU_RESULT} and a status of
-@code{GNUNET_SETU_STATUS_FAILURE} (and terminates the CADET channel).
-If the application accepts the request, it sends back a strata estimator
-using a message of type GNUNET_MESSAGE_TYPE_SETU_P2P_SE. The
-initiator evaluates the strata estimator and initiates the exchange of
-invertible Bloom filters, sending a GNUNET_MESSAGE_TYPE_SETU_P2P_IBF.
-During the IBF exchange, if the receiver cannot invert the Bloom filter or
-detects a cycle, it sends a larger IBF in response (up to a defined
-maximum limit; if that limit is reached, the operation fails).
-Elements decoded while processing the IBF are transmitted to the other
-peer using GNUNET_MESSAGE_TYPE_SETU_P2P_ELEMENTS, or requested from the
-other peer using GNUNET_MESSAGE_TYPE_SETU_P2P_ELEMENT_REQUESTS messages,
-depending on the sign observed during decoding of the IBF.
-Peers respond to a GNUNET_MESSAGE_TYPE_SETU_P2P_ELEMENT_REQUESTS message
-with the respective element in a GNUNET_MESSAGE_TYPE_SETU_P2P_ELEMENTS
-message. If the IBF fully decodes, the peer responds with a
-GNUNET_MESSAGE_TYPE_SETU_P2P_DONE message instead of another
-GNUNET_MESSAGE_TYPE_SETU_P2P_IBF.
-All Bloom filter operations use a salt to mingle keys before hashing them
-into buckets, such that future iterations have a fresh chance of
-succeeding if they failed due to collisions before.
-@cindex STATISTICS Subsystem
-@node STATISTICS Subsystem
-@section STATISTICS Subsystem
-In GNUnet, the STATISTICS subsystem offers a central place for all
-subsystems to publish unsigned 64-bit integer run-time statistics.
-Keeping this information centrally means that there is a unified way for
-the user to obtain data on all subsystems, and individual subsystems do
-not have to always include a custom data export method for performance
-metrics and other statistics. For example, the TRANSPORT system uses
-STATISTICS to update information about the number of directly connected
-peers and the bandwidth that has been consumed by the various plugins.
-This information is valuable for diagnosing connectivity and performance
-issues.
-Following the GNUnet service architecture, the STATISTICS subsystem is
-divided into an API which is exposed through the header
-@strong{gnunet_statistics_service.h} and the STATISTICS service
-@strong{gnunet-service-statistics}. The @strong{gnunet-statistics}
-command-line tool can be used to obtain (and change) information about
-the values stored by the STATISTICS service. The STATISTICS service does
-not communicate with other peers.
-Data is stored in the STATISTICS service in the form of tuples
-@strong{(subsystem, name, value, persistence)}. The subsystem determines
-to which other GNUnet's subsystem the data belongs. name is the name
-through which value is associated. It uniquely identifies the record
-from among other records belonging to the same subsystem.
-In some parts of the code, the pair @strong{(subsystem, name)} is called
-a @strong{statistic} as it identifies the values stored in the STATISTCS
-service.The persistence flag determines if the record has to be preserved
-across service restarts. A record is said to be persistent if this flag
-is set for it; if not, the record is treated as a non-persistent record
-and it is lost after service restart. Persistent records are written to
-and read from the file @strong{statistics.data} before shutdown
-and upon startup. The file is located in the HOME directory of the peer.
-An anomaly of the STATISTICS service is that it does not terminate
-immediately upon receiving a shutdown signal if it has any clients
-connected to it. It waits for all the clients that are not monitors to
-close their connections before terminating itself.
-This is to prevent the loss of data during peer shutdown --- delaying the
-STATISTICS service shutdown helps other services to store important data
-to STATISTICS during shutdown.
-@menu
-* libgnunetstatistics::
-* The STATISTICS Client-Service Protocol::
-@end menu
-@cindex libgnunetstatistics
-@node libgnunetstatistics
-@subsection libgnunetstatistics
-@strong{libgnunetstatistics} is the library containing the API for the
-STATISTICS subsystem. Any process requiring to use STATISTICS should use
-this API by to open a connection to the STATISTICS service.
-This is done by calling the function @code{GNUNET_STATISTICS_create()}.
-This function takes the subsystem's name which is trying to use STATISTICS
-and a configuration.
-All values written to STATISTICS with this connection will be placed in
-the section corresponding to the given subsystem's name.
-The connection to STATISTICS can be destroyed with the function
-@code{GNUNET_STATISTICS_destroy()}. This function allows for the
-connection to be destroyed immediately or upon transferring all
-pending write requests to the service.
-Note: STATISTICS subsystem can be disabled by setting @code{DISABLE = YES}
-under the @code{[STATISTICS]} section in the configuration. With such a
-configuration all calls to @code{GNUNET_STATISTICS_create()} return
-@code{NULL} as the STATISTICS subsystem is unavailable and no other
-functions from the API can be used.
-@menu
-* Statistics retrieval::
-* Setting statistics and updating them::
-* Watches::
-@end menu
-@node Statistics retrieval
-@subsubsection Statistics retrieval
-Once a connection to the statistics service is obtained, information
-about any other system which uses statistics can be retrieved with the
-function GNUNET_STATISTICS_get().
-This function takes the connection handle, the name of the subsystem
-whose information we are interested in (a @code{NULL} value will
-retrieve information of all available subsystems using STATISTICS), the
-name of the statistic we are interested in (a @code{NULL} value will
-retrieve all available statistics), a continuation callback which is
-called when all of requested information is retrieved, an iterator
-callback which is called for each parameter in the retrieved information
-and a closure for the aforementioned callbacks. The library then invokes
-the iterator callback for each value matching the request.
-Call to @code{GNUNET_STATISTICS_get()} is asynchronous and can be
-canceled with the function @code{GNUNET_STATISTICS_get_cancel()}.
-This is helpful when retrieving statistics takes too long and especially
-when we want to shutdown and cleanup everything.
-@node Setting statistics and updating them
-@subsubsection Setting statistics and updating them
-So far we have seen how to retrieve statistics, here we will learn how we
-can set statistics and update them so that other subsystems can retrieve
-them.
-A new statistic can be set using the function
-@code{GNUNET_STATISTICS_set()}.
-This function takes the name of the statistic and its value and a flag to
-make the statistic persistent.
-The value of the statistic should be of the type @code{uint64_t}.
-The function does not take the name of the subsystem; it is determined
-from the previous @code{GNUNET_STATISTICS_create()} invocation. If
-the given statistic is already present, its value is overwritten.
-An existing statistics can be updated, i.e its value can be increased or
-decreased by an amount with the function
-@code{GNUNET_STATISTICS_update()}.
-The parameters to this function are similar to
-@code{GNUNET_STATISTICS_set()}, except that it takes the amount to be
-changed as a type @code{int64_t} instead of the value.
-The library will combine multiple set or update operations into one
-message if the client performs requests at a rate that is faster than the
-available IPC with the STATISTICS service. Thus, the client does not have
-to worry about sending requests too quickly.
-@node Watches
-@subsubsection Watches
-As interesting feature of STATISTICS lies in serving notifications
-whenever a statistic of our interest is modified.
-This is achieved by registering a watch through the function
-@code{GNUNET_STATISTICS_watch()}.
-The parameters of this function are similar to those of
-@code{GNUNET_STATISTICS_get()}.
-Changes to the respective statistic's value will then cause the given
-iterator callback to be called.
-Note: A watch can only be registered for a specific statistic. Hence
-the subsystem name and the parameter name cannot be @code{NULL} in a
-call to @code{GNUNET_STATISTICS_watch()}.
-A registered watch will keep notifying any value changes until
-@code{GNUNET_STATISTICS_watch_cancel()} is called with the same
-parameters that are used for registering the watch.
-@node The STATISTICS Client-Service Protocol
-@subsection The STATISTICS Client-Service Protocol
-@menu
-* Statistics retrieval2::
-* Setting and updating statistics::
-* Watching for updates::
-@end menu
-@node Statistics retrieval2
-@subsubsection Statistics retrieval2
-To retrieve statistics, the client transmits a message of type
-@code{GNUNET_MESSAGE_TYPE_STATISTICS_GET} containing the given subsystem
-name and statistic parameter to the STATISTICS service.
-The service responds with a message of type
-@code{GNUNET_MESSAGE_TYPE_STATISTICS_VALUE} for each of the statistics
-parameters that match the client request for the client. The end of
-information retrieved is signaled by the service by sending a message of
-type @code{GNUNET_MESSAGE_TYPE_STATISTICS_END}.
-@node Setting and updating statistics
-@subsubsection Setting and updating statistics
-The subsystem name, parameter name, its value and the persistence flag are
-communicated to the service through the message
-@code{GNUNET_MESSAGE_TYPE_STATISTICS_SET}.
-When the service receives a message of type
-@code{GNUNET_MESSAGE_TYPE_STATISTICS_SET}, it retrieves the subsystem
-name and checks for a statistic parameter with matching the name given in
-the message.
-If a statistic parameter is found, the value is overwritten by the new
-value from the message; if not found then a new statistic parameter is
-created with the given name and value.
-In addition to just setting an absolute value, it is possible to perform a
-relative update by sending a message of type
-@code{GNUNET_MESSAGE_TYPE_STATISTICS_SET} with an update flag
-(@code{GNUNET_STATISTICS_SETFLAG_RELATIVE}) signifying that the value in
-the message should be treated as an update value.
-@node Watching for updates
-@subsubsection Watching for updates
-The function registers the watch at the service by sending a message of
-type @code{GNUNET_MESSAGE_TYPE_STATISTICS_WATCH}. The service then sends
-notifications through messages of type
-@code{GNUNET_MESSAGE_TYPE_STATISTICS_WATCH_VALUE} whenever the statistic
-parameter's value is changed.
-@cindex DHT
-@cindex Distributed Hash Table
-@node Distributed Hash Table (DHT)
-@section Distributed Hash Table (DHT)
-GNUnet includes a generic distributed hash table that can be used by
-developers building P2P applications in the framework.
-This section documents high-level features and how developers are
-expected to use the DHT.
-We have a research paper detailing how the DHT works.
-Also, Nate's thesis includes a detailed description and performance
-analysis (in chapter 6).
-Key features of GNUnet's DHT include:
-@itemize @bullet
-@item stores key-value pairs with values up to (approximately) 63k in size
-@item works with many underlay network topologies (small-world, random
-graph), underlay does not need to be a full mesh / clique
-@item support for extended queries (more than just a simple 'key'),
-filtering duplicate replies within the network (bloomfilter) and content
-validation (for details, please read the subsection on the block library)
-@item can (optionally) return paths taken by the PUT and GET operations
-to the application
-@item provides content replication to handle churn
-@end itemize
-GNUnet's DHT is randomized and unreliable. Unreliable means that there is
-no strict guarantee that a value stored in the DHT is always
-found --- values are only found with high probability.
-While this is somewhat true in all P2P DHTs, GNUnet developers should be
-particularly wary of this fact (this will help you write secure,
-fault-tolerant code). Thus, when writing any application using the DHT,
-you should always consider the possibility that a value stored in the
-DHT by you or some other peer might simply not be returned, or returned
-with a significant delay.
-Your application logic must be written to tolerate this (naturally, some
-loss of performance or quality of service is expected in this case).
-@menu
-* Block library and plugins::
-* libgnunetdht::
-* The DHT Client-Service Protocol::
-* The DHT Peer-to-Peer Protocol::
-@end menu
-@node Block library and plugins
-@subsection Block library and plugins
-@menu
-* What is a Block?::
-* The API of libgnunetblock::
-* Queries::
-* Sample Code::
-* Conclusion2::
-@end menu
-@node What is a Block?
-@subsubsection What is a Block?
-Blocks are small (< 63k) pieces of data stored under a key (struct
-GNUNET_HashCode). Blocks have a type (enum GNUNET_BlockType) which defines
-their data format. Blocks are used in GNUnet as units of static data
-exchanged between peers and stored (or cached) locally.
-Uses of blocks include file-sharing (the files are broken up into blocks),
-the VPN (DNS information is stored in blocks) and the DHT (all
-information in the DHT and meta-information for the maintenance of the
-DHT are both stored using blocks).
-The block subsystem provides a few common functions that must be
-available for any type of block.
-@cindex libgnunetblock API
-@node The API of libgnunetblock
-@subsubsection The API of libgnunetblock
-The block library requires for each (family of) block type(s) a block
-plugin (implementing @file{gnunet_block_plugin.h}) that provides basic
-functions that are needed by the DHT (and possibly other subsystems) to
-manage the block.
-These block plugins are typically implemented within their respective
-subsystems.
-The main block library is then used to locate, load and query the
-appropriate block plugin.
-Which plugin is appropriate is determined by the block type (which is
-just a 32-bit integer). Block plugins contain code that specifies which
-block types are supported by a given plugin. The block library loads all
-block plugins that are installed at the local peer and forwards the
-application request to the respective plugin.
-The central functions of the block APIs (plugin and main library) are to
-allow the mapping of blocks to their respective key (if possible) and the
-ability to check that a block is well-formed and matches a given
-request (again, if possible).
-This way, GNUnet can avoid storing invalid blocks, storing blocks under
-the wrong key and forwarding blocks in response to a query that they do
-not answer.
-One key function of block plugins is that it allows GNUnet to detect
-duplicate replies (via the Bloom filter). All plugins MUST support
-detecting duplicate replies (by adding the current response to the
-Bloom filter and rejecting it if it is encountered again).
-If a plugin fails to do this, responses may loop in the network.
-@node Queries
-@subsubsection Queries
-The query format for any block in GNUnet consists of four main components.
-First, the type of the desired block must be specified. Second, the query
-must contain a hash code. The hash code is used for lookups in hash
-tables and databases and must not be unique for the block (however, if
-possible a unique hash should be used as this would be best for
-performance).
-Third, an optional Bloom filter can be specified to exclude known results;
-replies that hash to the bits set in the Bloom filter are considered
-invalid. False-positives can be eliminated by sending the same query
-again with a different Bloom filter mutator value, which parametrizes
-the hash function that is used.
-Finally, an optional application-specific "eXtended query" (xquery) can
-be specified to further constrain the results. It is entirely up to
-the type-specific plugin to determine whether or not a given block
-matches a query (type, hash, Bloom filter, and xquery).
-Naturally, not all xquery's are valid and some types of blocks may not
-support Bloom filters either, so the plugin also needs to check if the
-query is valid in the first place.
-Depending on the results from the plugin, the DHT will then discard the
-(invalid) query, forward the query, discard the (invalid) reply, cache the
-(valid) reply, and/or forward the (valid and non-duplicate) reply.
-@node Sample Code
-@subsubsection Sample Code
-The source code in @strong{plugin_block_test.c} is a good starting point
-for new block plugins --- it does the minimal work by implementing a
-plugin that performs no validation at all.
-The respective @strong{Makefile.am} shows how to build and install a
-block plugin.
-@node Conclusion2
-@subsubsection Conclusion2
-In conclusion, GNUnet subsystems that want to use the DHT need to define a
-block format and write a plugin to match queries and replies. For testing,
-the @code{GNUNET_BLOCK_TYPE_TEST} block type can be used; it accepts
-any query as valid and any reply as matching any query.
-This type is also used for the DHT command line tools.
-However, it should NOT be used for normal applications due to the lack
-of error checking that results from this primitive implementation.
-@cindex libgnunetdht
-@node libgnunetdht
-@subsection libgnunetdht
-The DHT API itself is pretty simple and offers the usual GET and PUT
-functions that work as expected. The specified block type refers to the
-block library which allows the DHT to run application-specific logic for
-data stored in the network.
-@menu
-* GET::
-* PUT::
-* MONITOR::
-* DHT Routing Options::
-@end menu
-@node GET
-@subsubsection GET
-When using GET, the main consideration for developers (other than the
-block library) should be that after issuing a GET, the DHT will
-continuously cause (small amounts of) network traffic until the operation
-is explicitly canceled.
-So GET does not simply send out a single network request once; instead,
-the DHT will continue to search for data. This is needed to achieve good
-success rates and also handles the case where the respective PUT
-operation happens after the GET operation was started.
-Developers should not cancel an existing GET operation and then
-explicitly re-start it to trigger a new round of network requests;
-this is simply inefficient, especially as the internal automated version
-can be more efficient, for example by filtering results in the network
-that have already been returned.
-If an application that performs a GET request has a set of replies that it
-already knows and would like to filter, it can call@
-@code{GNUNET_DHT_get_filter_known_results} with an array of hashes over
-the respective blocks to tell the DHT that these results are not
-desired (any more).
-This way, the DHT will filter the respective blocks using the block
-library in the network, which may result in a significant reduction in
-bandwidth consumption.
-@node PUT
-@subsubsection PUT
-@c inconsistent use of ``must'' above it's written ``MUST''
-In contrast to GET operations, developers @strong{must} manually re-run
-PUT operations periodically (if they intend the content to continue to be
-available). Content stored in the DHT expires or might be lost due to
-churn.
-Furthermore, GNUnet's DHT typically requires multiple rounds of PUT
-operations before a key-value pair is consistently available to all
-peers (the DHT randomizes paths and thus storage locations, and only
-after multiple rounds of PUTs there will be a sufficient number of
-replicas in large DHTs). An explicit PUT operation using the DHT API will
-only cause network traffic once, so in order to ensure basic availability
-and resistance to churn (and adversaries), PUTs must be repeated.
-While the exact frequency depends on the application, a rule of thumb is
-that there should be at least a dozen PUT operations within the content
-lifetime. Content in the DHT typically expires after one day, so
-DHT PUT operations should be repeated at least every 1-2 hours.
-@node MONITOR
-@subsubsection MONITOR
-The DHT API also allows applications to monitor messages crossing the
-local DHT service.
-The types of messages used by the DHT are GET, PUT and RESULT messages.
-Using the monitoring API, applications can choose to monitor these
-requests, possibly limiting themselves to requests for a particular block
-type.
-The monitoring API is not only useful for diagnostics, it can also be
-used to trigger application operations based on PUT operations.
-For example, an application may use PUTs to distribute work requests to
-other peers.
-The workers would then monitor for PUTs that give them work, instead of
-looking for work using GET operations.
-This can be beneficial, especially if the workers have no good way to
-guess the keys under which work would be stored.
-Naturally, additional protocols might be needed to ensure that the desired
-number of workers will process the distributed workload.
-@node DHT Routing Options
-@subsubsection DHT Routing Options
-There are two important options for GET and PUT requests:
-@table @asis
-@item GNUNET_DHT_RO_DEMULITPLEX_EVERYWHERE This option means that all
-peers should process the request, even if their peer ID is not closest to
-the key. For a PUT request, this means that all peers that a request
-traverses may make a copy of the data.
-Similarly for a GET request, all peers will check their local database
-for a result. Setting this option can thus significantly improve caching
-and reduce bandwidth consumption --- at the expense of a larger DHT
-database. If in doubt, we recommend that this option should be used.
-@item GNUNET_DHT_RO_RECORD_ROUTE This option instructs the DHT to record
-the path that a GET or a PUT request is taking through the overlay
-network. The resulting paths are then returned to the application with
-the respective result. This allows the receiver of a result to construct
-a path to the originator of the data, which might then be used for
-routing. Naturally, setting this option requires additional bandwidth
-and disk space, so applications should only set this if the paths are
-needed by the application logic.
-@item GNUNET_DHT_RO_FIND_PEER This option is an internal option used by
-the DHT's peer discovery mechanism and should not be used by applications.
-@item GNUNET_DHT_RO_BART This option is currently not implemented. It may
-in the future offer performance improvements for clique topologies.
-@end table
-@node The DHT Client-Service Protocol
-@subsection The DHT Client-Service Protocol
-@menu
-* PUTting data into the DHT::
-* GETting data from the DHT::
-* Monitoring the DHT::
-@end menu
-@node PUTting data into the DHT
-@subsubsection PUTting data into the DHT
-To store (PUT) data into the DHT, the client sends a
-@code{struct GNUNET_DHT_ClientPutMessage} to the service.
-This message specifies the block type, routing options, the desired
-replication level, the expiration time, key,
-value and a 64-bit unique ID for the operation. The service responds with
-a @code{struct GNUNET_DHT_ClientPutConfirmationMessage} with the same
-64-bit unique ID. Note that the service sends the confirmation as soon as
-it has locally processed the PUT request. The PUT may still be
-propagating through the network at this time.
-In the future, we may want to change this to provide (limited) feedback
-to the client, for example if we detect that the PUT operation had no
-effect because the same key-value pair was already stored in the DHT.
-However, changing this would also require additional state and messages
-in the P2P interaction.
-@node GETting data from the DHT
-@subsubsection GETting data from the DHT
-To retrieve (GET) data from the DHT, the client sends a
-@code{struct GNUNET_DHT_ClientGetMessage} to the service. The message
-specifies routing options, a replication level (for replicating the GET,
-not the content), the desired block type, the key, the (optional)
-extended query and unique 64-bit request ID.
-Additionally, the client may send any number of
-@code{struct GNUNET_DHT_ClientGetResultSeenMessage}s to notify the
-service about results that the client is already aware of.
-These messages consist of the key, the unique 64-bit ID of the request,
-and an arbitrary number of hash codes over the blocks that the client is
-already aware of. As messages are restricted to 64k, a client that
-already knows more than about a thousand blocks may need to send
-several of these messages. Naturally, the client should transmit these
-messages as quickly as possible after the original GET request such that
-the DHT can filter those results in the network early on. Naturally, as
-these messages are sent after the original request, it is conceivable
-that the DHT service may return blocks that match those already known
-to the client anyway.
-In response to a GET request, the service will send @code{struct
-GNUNET_DHT_ClientResultMessage}s to the client. These messages contain the
-block type, expiration, key, unique ID of the request and of course the
-value (a block). Depending on the options set for the respective
-operations, the replies may also contain the path the GET and/or the PUT
-took through the network.
-A client can stop receiving replies either by disconnecting or by sending
-a @code{struct GNUNET_DHT_ClientGetStopMessage} which must contain the
-key and the 64-bit unique ID of the original request. Using an
-explicit "stop" message is more common as this allows a client to run
-many concurrent GET operations over the same connection with the DHT
-service --- and to stop them individually.
-@node Monitoring the DHT
-@subsubsection Monitoring the DHT
-To begin monitoring, the client sends a
-@code{struct GNUNET_DHT_MonitorStartStop} message to the DHT service.
-In this message, flags can be set to enable (or disable) monitoring of
-GET, PUT and RESULT messages that pass through a peer. The message can
-also restrict monitoring to a particular block type or a particular key.
-Once monitoring is enabled, the DHT service will notify the client about
-any matching event using @code{struct GNUNET_DHT_MonitorGetMessage}s for
-GET events, @code{struct GNUNET_DHT_MonitorPutMessage} for PUT events
-and @code{struct GNUNET_DHT_MonitorGetRespMessage} for RESULTs. Each of
-these messages contains all of the information about the event.
-@node The DHT Peer-to-Peer Protocol
-@subsection The DHT Peer-to-Peer Protocol
-@menu
-* Routing GETs or PUTs::
-* PUTting data into the DHT2::
-* GETting data from the DHT2::
-@end menu
-@node Routing GETs or PUTs
-@subsubsection Routing GETs or PUTs
-When routing GETs or PUTs, the DHT service selects a suitable subset of
-neighbours for forwarding. The exact number of neighbours can be zero or
-more and depends on the hop counter of the query (initially zero) in
-relation to the (log of) the network size estimate, the desired
-replication level and the peer's connectivity.
-Depending on the hop counter and our network size estimate, the selection
-of the peers maybe randomized or by proximity to the key.
-Furthermore, requests include a set of peers that a request has already
-traversed; those peers are also excluded from the selection.
-@node PUTting data into the DHT2
-@subsubsection PUTting data into the DHT2
-To PUT data into the DHT, the service sends a @code{struct PeerPutMessage}
-of type @code{GNUNET_MESSAGE_TYPE_DHT_P2P_PUT} to the respective
-neighbour.
-In addition to the usual information about the content (type, routing
-options, desired replication level for the content, expiration time, key
-and value), the message contains a fixed-size Bloom filter with
-information about which peers (may) have already seen this request.
-This Bloom filter is used to ensure that DHT messages never loop back to
-a peer that has already processed the request.
-Additionally, the message includes the current hop counter and, depending
-on the routing options, the message may include the full path that the
-message has taken so far.
-The Bloom filter should already contain the identity of the previous hop;
-however, the path should not include the identity of the previous hop and
-the receiver should append the identity of the sender to the path, not
-its own identity (this is done to reduce bandwidth).
-@node GETting data from the DHT2
-@subsubsection GETting data from the DHT2
-A peer can search the DHT by sending @code{struct PeerGetMessage}s of type
-@code{GNUNET_MESSAGE_TYPE_DHT_P2P_GET} to other peers. In addition to the
-usual information about the request (type, routing options, desired
-replication level for the request, the key and the extended query), a GET
-request also contains a hop counter, a Bloom filter over the peers
-that have processed the request already and depending on the routing
-options the full path traversed by the GET.
-Finally, a GET request includes a variable-size second Bloom filter and a
-so-called Bloom filter mutator value which together indicate which
-replies the sender has already seen. During the lookup, each block that
-matches they block type, key and extended query is additionally subjected
-to a test against this Bloom filter.
-The block plugin is expected to take the hash of the block and combine it
-with the mutator value and check if the result is not yet in the Bloom
-filter. The originator of the query will from time to time modify the
-mutator to (eventually) allow false-positives filtered by the Bloom filter
-to be returned.
-Peers that receive a GET request perform a local lookup (depending on
-their proximity to the key and the query options) and forward the request
-to other peers.
-They then remember the request (including the Bloom filter for blocking
-duplicate results) and when they obtain a matching, non-filtered response
-a @code{struct PeerResultMessage} of type
-@code{GNUNET_MESSAGE_TYPE_DHT_P2P_RESULT} is forwarded to the previous
-hop.
-Whenever a result is forwarded, the block plugin is used to update the
-Bloom filter accordingly, to ensure that the same result is never
-forwarded more than once.
-The DHT service may also cache forwarded results locally if the
-"CACHE_RESULTS" option is set to "YES" in the configuration.
-@cindex GNS
-@cindex GNU Name System
-@node GNU Name System (GNS)
-@section GNU Name System (GNS)
-The GNU Name System (GNS) is a decentralized database that enables users
-to securely resolve names to values.
-Names can be used to identify other users (for example, in social
-networking), or network services (for example, VPN services running at a
-peer in GNUnet, or purely IP-based services on the Internet).
-Users interact with GNS by typing in a hostname that ends in a
-top-level domain that is configured in the ``GNS'' section, matches
-an identity of the user or ends in a Base32-encoded public key.
-Videos giving an overview of most of the GNS and the motivations behind
-it is available here and here.
-The remainder of this chapter targets developers that are familiar with
-high level concepts of GNS as presented in these talks.
-@c TODO: Add links to here and here and to these.
-GNS-aware applications should use the GNS resolver to obtain the
-respective records that are stored under that name in GNS.
-Each record consists of a type, value, expiration time and flags.
-The type specifies the format of the value. Types below 65536 correspond
-to DNS record types, larger values are used for GNS-specific records.
-Applications can define new GNS record types by reserving a number and
-implementing a plugin (which mostly needs to convert the binary value
-representation to a human-readable text format and vice-versa).
-The expiration time specifies how long the record is to be valid.
-The GNS API ensures that applications are only given non-expired values.
-The flags are typically irrelevant for applications, as GNS uses them
-internally to control visibility and validity of records.
-Records are stored along with a signature.
-The signature is generated using the private key of the authoritative
-zone. This allows any GNS resolver to verify the correctness of a
-name-value mapping.
-Internally, GNS uses the NAMECACHE to cache information obtained from
-other users, the NAMESTORE to store information specific to the local
-users, and the DHT to exchange data between users.
-A plugin API is used to enable applications to define new GNS
-record types.
-@menu
-* libgnunetgns::
-* libgnunetgnsrecord::
-* GNS plugins::
-* The GNS Client-Service Protocol::
-* Hijacking the DNS-Traffic using gnunet-service-dns::
-@c * Serving DNS lookups via GNS on W32::
-* Importing DNS Zones into GNS::
-* Registering names using the FCFS daemon::
-@end menu
-@node libgnunetgns
-@subsection libgnunetgns
-The GNS API itself is extremely simple. Clients first connect to the
-GNS service using @code{GNUNET_GNS_connect}.
-They can then perform lookups using @code{GNUNET_GNS_lookup} or cancel
-pending lookups using @code{GNUNET_GNS_lookup_cancel}.
-Once finished, clients disconnect using @code{GNUNET_GNS_disconnect}.
-@menu
-* Looking up records::
-* Accessing the records::
-* Creating records::
-* Future work::
-@end menu
-@node Looking up records
-@subsubsection Looking up records
-@code{GNUNET_GNS_lookup} takes a number of arguments:
-@table @asis
-@item handle This is simply the GNS connection handle from
-@code{GNUNET_GNS_connect}.
-@item name The client needs to specify the name to
-be resolved. This can be any valid DNS or GNS hostname.
-@item zone The client
-needs to specify the public key of the GNS zone against which the
-resolution should be done.
-Note that a key must be provided, the client should
-look up plausible values using its configuration,
-the identity service and by attempting to interpret the
-TLD as a base32-encoded public key.
-@item type This is the desired GNS or DNS record type
-to look for. While all records for the given name will be returned, this
-can be important if the client wants to resolve record types that
-themselves delegate resolution, such as CNAME, PKEY or GNS2DNS.
-Resolving a record of any of these types will only work if the respective
-record type is specified in the request, as the GNS resolver will
-otherwise follow the delegation and return the records from the
-respective destination, instead of the delegating record.
-@item only_cached This argument should typically be set to
-@code{GNUNET_NO}. Setting it to @code{GNUNET_YES} disables resolution via
-the overlay network.
-@item shorten_zone_key If GNS encounters new names during resolution,
-their respective zones can automatically be learned and added to the
-"shorten zone". If this is desired, clients must pass the private key of
-the shorten zone. If NULL is passed, shortening is disabled.
-@item proc This argument identifies
-the function to call with the result. It is given proc_cls, the number of
-records found (possibly zero) and the array of the records as arguments.
-proc will only be called once. After proc,> has been called, the lookup
-must no longer be canceled.
-@item proc_cls The closure for proc.
-@end table
-@node Accessing the records
-@subsubsection Accessing the records
-The @code{libgnunetgnsrecord} library provides an API to manipulate the
-GNS record array that is given to proc. In particular, it offers
-functions such as converting record values to human-readable
-strings (and back). However, most @code{libgnunetgnsrecord} functions are
-not interesting to GNS client applications.
-For DNS records, the @code{libgnunetdnsparser} library provides
-functions for parsing (and serializing) common types of DNS records.
-@node Creating records
-@subsubsection Creating records
-Creating GNS records is typically done by building the respective record
-information (possibly with the help of @code{libgnunetgnsrecord} and
-@code{libgnunetdnsparser}) and then using the @code{libgnunetnamestore} to
-publish the information. The GNS API is not involved in this
-operation.
-@node Future work
-@subsubsection Future work
-In the future, we want to expand @code{libgnunetgns} to allow
-applications to observe shortening operations performed during GNS
-resolution, for example so that users can receive visual feedback when
-this happens.
-@node libgnunetgnsrecord
-@subsection libgnunetgnsrecord
-The @code{libgnunetgnsrecord} library is used to manipulate GNS
-records (in plaintext or in their encrypted format).
-Applications mostly interact with @code{libgnunetgnsrecord} by using the
-functions to convert GNS record values to strings or vice-versa, or to
-lookup a GNS record type number by name (or vice-versa).
-The library also provides various other functions that are mostly
-used internally within GNS, such as converting keys to names, checking for
-expiration, encrypting GNS records to GNS blocks, verifying GNS block
-signatures and decrypting GNS records from GNS blocks.
-We will now discuss the four commonly used functions of the API.@
-@code{libgnunetgnsrecord} does not perform these operations itself,
-but instead uses plugins to perform the operation.
-GNUnet includes plugins to support common DNS record types as well as
-standard GNS record types.
-@menu
-* Value handling::
-* Type handling::
-@end menu
-@node Value handling
-@subsubsection Value handling
-@code{GNUNET_GNSRECORD_value_to_string} can be used to convert
-the (binary) representation of a GNS record value to a human readable,
-0-terminated UTF-8 string.
-NULL is returned if the specified record type is not supported by any
-available plugin.
-@code{GNUNET_GNSRECORD_string_to_value} can be used to try to convert a
-human readable string to the respective (binary) representation of
-a GNS record value.
-@node Type handling
-@subsubsection Type handling
-@code{GNUNET_GNSRECORD_typename_to_number} can be used to obtain the
-numeric value associated with a given typename. For example, given the
-typename "A" (for DNS A reocrds), the function will return the number 1.
-A list of common DNS record types is
-@uref{http://en.wikipedia.org/wiki/List_of_DNS_record_types, here}.
-Note that not all DNS record types are supported by GNUnet GNSRECORD
-plugins at this time.
-@code{GNUNET_GNSRECORD_number_to_typename} can be used to obtain the
-typename associated with a given numeric value.
-For example, given the type number 1, the function will return the
-typename "A".
-@node GNS plugins
-@subsection GNS plugins
-Adding a new GNS record type typically involves writing (or extending) a
-GNSRECORD plugin. The plugin needs to implement the
-@code{gnunet_gnsrecord_plugin.h} API which provides basic functions that
-are needed by GNSRECORD to convert typenames and values of the respective
-record type to strings (and back).
-These gnsrecord plugins are typically implemented within their respective
-subsystems.
-Examples for such plugins can be found in the GNSRECORD, GNS and
-CONVERSATION subsystems.
-The @code{libgnunetgnsrecord} library is then used to locate, load and
-query the appropriate gnsrecord plugin.
-Which plugin is appropriate is determined by the record type (which is
-just a 32-bit integer). The @code{libgnunetgnsrecord} library loads all
-block plugins that are installed at the local peer and forwards the
-application request to the plugins. If the record type is not
-supported by the plugin, it should simply return an error code.
-The central functions of the block APIs (plugin and main library) are the
-same four functions for converting between values and strings, and
-typenames and numbers documented in the previous subsection.
-@node The GNS Client-Service Protocol
-@subsection The GNS Client-Service Protocol
-The GNS client-service protocol consists of two simple messages, the
-@code{LOOKUP} message and the @code{LOOKUP_RESULT}. Each @code{LOOKUP}
-message contains a unique 32-bit identifier, which will be included in the
-corresponding response. Thus, clients can send many lookup requests in
-parallel and receive responses out-of-order.
-A @code{LOOKUP} request also includes the public key of the GNS zone,
-the desired record type and fields specifying whether shortening is
-enabled or networking is disabled. Finally, the @code{LOOKUP} message
-includes the name to be resolved.
-The response includes the number of records and the records themselves
-in the format created by @code{GNUNET_GNSRECORD_records_serialize}.
-They can thus be deserialized using
-@code{GNUNET_GNSRECORD_records_deserialize}.
-@node Hijacking the DNS-Traffic using gnunet-service-dns
-@subsection Hijacking the DNS-Traffic using gnunet-service-dns
-This section documents how the gnunet-service-dns (and the
-gnunet-helper-dns) intercepts DNS queries from the local system.
-This is merely one method for how we can obtain GNS queries.
-It is also possible to change @code{resolv.conf} to point to a machine
-running @code{gnunet-dns2gns} or to modify libc's name system switch
-(NSS) configuration to include a GNS resolution plugin.
-The method described in this chapter is more of a last-ditch catch-all
-approach.
-@code{gnunet-service-dns} enables intercepting DNS traffic using policy
-based routing.
-We MARK every outgoing DNS-packet if it was not sent by our application.
-Using a second routing table in the Linux kernel these marked packets are
-then routed through our virtual network interface and can thus be
-captured unchanged.
-Our application then reads the query and decides how to handle it.
-If the query can be addressed via GNS, it is passed to
-@code{gnunet-service-gns} and resolved internally using GNS.
-In the future, a reverse query for an address of the configured virtual
-network could be answered with records kept about previous forward
-queries.
-Queries that are not hijacked by some application using the DNS service
-will be sent to the original recipient.
-The answer to the query will always be sent back through the virtual
-interface with the original nameserver as source address.
-@menu
-* Network Setup Details::
-@end menu
-@node Network Setup Details
-@subsubsection Network Setup Details
-The DNS interceptor adds the following rules to the Linux kernel:
-@example
-iptables -t mangle -I OUTPUT 1 -p udp --sport $LOCALPORT --dport 53 \
-j ACCEPT iptables -t mangle -I OUTPUT 2 -p udp --dport 53 -j MARK \
--set-mark 3 ip rule add fwmark 3 table2 ip route add default via \
-$VIRTUALDNS table2
-@end example
-@c FIXME: Rewrite to reflect display which is no longer content by line
-@c FIXME: due to the < 74 characters limit.
-Line 1 makes sure that all packets coming from a port our application
-opened beforehand (@code{$LOCALPORT}) will be routed normally.
-Line 2 marks every other packet to a DNS-Server with mark 3 (chosen
-arbitrarily). The third line adds a routing policy based on this mark
-3 via the routing table.
-@c @node Serving DNS lookups via GNS on W32
-@c @subsection Serving DNS lookups via GNS on W32
-@c This section documents how the libw32nsp (and
-@c gnunet-gns-helper-service-w32) do DNS resolutions of DNS queries on the
-@c local system. This only applies to GNUnet running on W32.
-@c W32 has a concept of "Namespaces" and "Namespace providers".
-@c These are used to present various name systems to applications in a
-@c generic way.
-@c Namespaces include DNS, mDNS, NLA and others. For each namespace any
-@c number of providers could be registered, and they are queried in an order
-@c of priority (which is adjustable).
-@c Applications can resolve names by using WSALookupService*() family of
-@c functions.
-@c However, these are WSA-only facilities. Common BSD socket functions for
-@c namespace resolutions are gethostbyname and getaddrinfo (among others).
-@c These functions are implemented internally (by default - by mswsock,
-@c which also implements the default DNS provider) as wrappers around
-@c WSALookupService*() functions (see "Sample Code for a Service Provider"
-@c on MSDN).
-@c On W32 GNUnet builds a libw32nsp - a namespace provider, which can then be
-@c installed into the system by using w32nsp-install (and uninstalled by
-@c w32nsp-uninstall), as described in "Installation Handbook".
-@c libw32nsp is very simple and has almost no dependencies. As a response to
-@c NSPLookupServiceBegin(), it only checks that the provider GUID passed to
-@c it by the caller matches GNUnet DNS Provider GUID,
-@c then connects to
-@c gnunet-gns-helper-service-w32 at 127.0.0.1:5353 (hardcoded) and sends the
-@c name resolution request there, returning the connected socket to the
-@c caller.
-@c When the caller invokes NSPLookupServiceNext(), libw32nsp reads a
-@c completely formed reply from that socket, unmarshalls it, then gives
-@c it back to the caller.
-@c At the moment gnunet-gns-helper-service-w32 is implemented to ever give
-@c only one reply, and subsequent calls to NSPLookupServiceNext() will fail
-@c with WSA_NODATA (first call to NSPLookupServiceNext() might also fail if
-@c GNS failed to find the name, or there was an error connecting to it).
-@c gnunet-gns-helper-service-w32 does most of the processing:
-@c @itemize @bullet
-@c @item Maintains a connection to GNS.
-@c @item Reads GNS config and loads appropriate keys.
-@c @item Checks service GUID and decides on the type of record to look up,
-@c refusing to make a lookup outright when unsupported service GUID is
-@c passed.
-@c @item Launches the lookup
-@c @end itemize
-@c When lookup result arrives, gnunet-gns-helper-service-w32 forms a complete
-@c reply (including filling a WSAQUERYSETW structure and, possibly, a binary
-@c blob with a hostent structure for gethostbyname() client), marshalls it,
-@c and sends it back to libw32nsp. If no records were found, it sends an
-@c empty header.
-@c This works for most normal applications that use gethostbyname() or
-@c getaddrinfo() to resolve names, but fails to do anything with
-@c applications that use alternative means of resolving names (such as
-@c sending queries to a DNS server directly by themselves).
-@c This includes some of well known utilities, like "ping" and "nslookup".
-@node Importing DNS Zones into GNS
-@subsection Importing DNS Zones into GNS
-This section discusses the challenges and problems faced when writing the
-Ascension tool. It also takes a look at possible improvements in the
-future.
-Consider the following diagram that shows the workflow of Ascension:
-@image{images/ascension_ssd,6in,,Ascensions workflow}
-Further the interaction between components of GNUnet are shown in the diagram
-below:
-@center @image{images/ascension_interaction,,6in,Ascensions workflow}
-@menu
-* Conversions between DNS and GNS::
-* DNS Zone Size::
-* Performance::
-@end menu
-@cindex DNS Conversion
-@node Conversions between DNS and GNS
-@subsubsection Conversions between DNS and GNS
-The differences between the two name systems lies in the details and is not
-always transparent.  For instance an SRV record is converted to a BOX record
-which is unique to GNS.
-This is done by converting to a BOX record from an existing SRV record:
-@example
-# SRV
-# _service._proto.name. TTL class SRV priority weight port target
-_sip._tcp.example.com. 14000 IN SRV     0 0 5060 www.example.com.
-# BOX
-# TTL BOX flags port protocol recordtype priority weight port target
-14000 BOX n 5060 6 33 0 0 5060 www.example.com
-@end example
-Other records that need to undergo such transformation is the MX record type,
-as well as the SOA record type.
-Transformation of a SOA record into GNS works as described in the
-following example. Very important to note are the rname and mname keys.
-@example
-# BIND syntax for a clean SOA record
-@   IN SOA master.example.com. hostmaster.example.com. (
-    2017030300 ; serial
-    3600       ; refresh
-    1800       ; retry
-    604800     ; expire
-    600 )      ; ttl
-# Recordline for adding the record
-$ gnunet-namestore -z example.com -a -n @ -t SOA -V \
-    rname=master.example.com mname=hostmaster.example.com  \
-    2017030300,3600,1800,604800,600 -e 7200s
-@end example
-The transformation of MX records is done in a simple way.
-@example
-# mail.example.com. 3600 IN MX 10 mail.example.com.
-$ gnunet-namestore -z example.com -n mail -R 3600 MX n 10,mail
-@end example
-Finally, one of the biggest struggling points were the NS records that are
-found in top level domain zones. The intended behaviour for those is to add
-GNS2DNS records for those so that gnunet-gns can resolve records for those
-domains on its own. Those require the values from DNS GLUE records, provided
-they are within the same zone.
-The following two examples show one record with a GLUE record and the other one
-does not have a GLUE record. This takes place in the 'com' TLD.
-@example
-# ns1.example.com 86400 IN A 127.0.0.1
-# example.com 86400 IN NS ns1.example.com.
-$ gnunet-namestore -z com -n example -R 86400 GNS2DNS n \
-    example.com@@127.0.0.1
-# example.com 86400 IN NS ns1.example.org.
-$ gnunet-namestore -z com -n example -R 86400 GNS2DNS n \
-    example.com@@ns1.example.org
-@end example
-As you can see, one of the GNS2DNS records has an IP address listed and the
-other one a DNS name. For the first one there is a GLUE record to do the
-translation directly and the second one will issue another DNS query to figure
-out the IP of ns1.example.org.
-A solution was found by creating a hierarchical zone structure in GNS and linking
-the zones using PKEY records to one another. This allows the resolution of the
-name servers to work within GNS while not taking control over unwanted zones.
-Currently the following record types are supported:
-@itemize @bullet
-@item A
-@item AAAA
-@item CNAME
-@item MX
-@item NS
-@item SRV
-@item TXT
-@end itemize
-This is not due to technical limitations but rather a practical ones. The
-problem occurs with DNSSEC enabled DNS zones. As records within those zones are
-signed periodically, and every new signature is an update to the zone, there are
-many revisions of zones. This results in a problem with bigger zones as there
-are lots of records that have been signed again but no major changes.  Also
-trying to add records that are unknown that require a different format take time
-as they cause a CLI call of the namestore.  Furthermore certain record types
-need transformation into a GNS compatible format which, depending on the record
-type, takes more time.
-Further a blacklist was added to drop for instance DNSSEC related records. Also
-if a record type is neither in the white list nor the blacklist it is considered
-as a loss of data and a message is shown to the user. This helps with
-transparency and also with contributing, as the not supported record types can
-then be added accordingly.
-@node DNS Zone Size
-@subsubsection DNS Zone Size
-Another very big problem exists with very large zones. When migrating a small
-zone the delay between adding of records and their expiry is negligible. However
-when working with big zones that easily have more than a few million records
-this delay becomes a problem.
-Records will start to expire well before the zone has finished migrating. This
-is usually not a problem but can cause a high CPU load when a peer is restarted
-and the records have expired.
-A good solution has not been found yet. One of the idea that floated around was
-that the records should be added with the s (shadow) flag to keep the records
-resolvable even if they expired. However this would introduce the problem of how
-to detect if a record has been removed from the zone and would require deletion
-of said record(s).
-Another problem that still persists is how to refresh records. Expired records
-are still displayed when calling gnunet-namestore but do not resolve with
-gnunet-gns. Zonemaster will sign the expired records again and make sure that
-the records are still valid. With a recent change this was fixed as gnunet-gns
-to improve the suffix lookup which allows for a fast lookup even with thousands
-of local egos.
-Currently the pace of adding records in general is around 10 records per second.
-Crypto is the upper limit for adding of records. The performance of your machine
-can be tested with the perf_crypto_* tools. There is still a big discrepancy
-between the pace of Ascension and the theoretical limit.
-A performance metric for measuring improvements has not yet been implemented in
-Ascension.
-@node Performance
-@subsubsection Performance
-The performance when migrating a zone using the Ascension tool is limited by a
-handful of factors. First of all ascension is written in Python3 and calls the
-CLI tools of GNUnet. This is comparable to a fork and exec call which costs a
-few CPU cycles. Furthermore all the records that are added to the same
-label are signed using the zones private key. This signing operation is very
-resource heavy and was optimized during development by adding the '-R'
-(Recordline) option to gnunet-namestore which allows to specify multiple records
-using the CLI tool. Assuming that in a TLD zone every domain has at least two
-name servers this halves the amount of signatures needed.
-Another improvement that could be made is with the addition of multiple threads
-or using asynchronous subprocesses when opening the GNUnet CLI tools. This could
-be implemented by simply creating more workers in the program but performance
-improvements were not tested.
-Ascension was tested using different hardware and database backends. Performance
-differences between SQLite and postgresql are marginal and almost non existent.
-What did make a huge impact on record adding performance was the storage medium.
-On a traditional mechanical hard drive adding of records were slow compared to a
-solid state disk.
-In conclusion there are many bottlenecks still around in the program, namely the
-single threaded implementation and inefficient, sequential calls of
-gnunet-namestore. In the future a solution that uses the C API would be cleaner
-and better.
-@node Registering names using the FCFS daemon
-@subsection Registering names using the FCFS daemon
-This section describes FCFSD, a daemon used to associate names with PKEY
-records following a ``First Come, First Served'' policy.  This policy means
-that a certain name can not be registered again if someone registered it
-already.
-The daemon can be started by using @code{gnunet-namestore-fcfsd}, which will
-start a simple HTTP server on localhost, using a port specified by the
-@code{HTTPORT} value in its configuration.
-Communication is performed by sending GET or POST requests to specific paths
-(``endpoints''), as described in the following sections.
-The daemon will always respond with data structured using the JSON format.
-The fields to be expected will be listed for each endpoint.
-The only exceptions are for the ``root'' endpoint (i.e. @code{/}) which will
-return a HTML document, and two other HTML documents which will be served when
-certain errors are encountered, like when requesting an unknown endpoint.
-@menu
-* Obtaining information from the daemon::
-* Submitting data to the daemon::
-* Customizing the HTML output::
-@end menu
-@cindex FCFSD GET requests
-@node Obtaining information from the daemon
-@subsubsection Obtaining information from the daemon
-To query the daemon, a GET request must be sent to these endpoints, placing
-parameters in the address as per the HTTP specification, like so:
-@example
-GET /endpoint?param1=value&param2=value
-@end example
-Each endpoint will be described using its name (@code{/endpoint} in the
-example above), followed by the name of each parameter (like @code{param1} and
-@code{param2}.)
-@deffn Endpoint /search name
-This endpoint is used to query about the state of @var{name}, that is, whether
-it is available for registration or not.
-The response JSON will contain two fields:
-@itemize @bullet
-@item error
-@item free
-@end itemize
-@code{error} can be either the string @code{"true"} or the string
-@code{"false"}: when @code{"true"}, it means there was an error within the
-daemon and the name could not be searched at all.
-@code{free} can be either the string @code{"true"} or the string
-@code{"false"}: when @code{"true"}, the requested name can be registered.
-@end deffn
-@cindex FCFSD POST requests
-@node Submitting data to the daemon
-@subsubsection Submitting data to the daemon
-To send data to the daemon, a POST request must be sent to these endpoints,
-placing the data to submit in the body of the request, structured using the
-JSON format, like so:
-@example
-POST /endpoint
-Content-Type: application/json
-...
-@{"param1": value1, "param2": value2, ...@}
-@end example
-Each endpoint will be described using its name (@code{/endpoint} in the
-example above), followed by the name of each JSON field (like @code{param1}
-and @code{param2}.)
-@deffn Endpoint /register name key
-This endpoint is used to register a new association between @var{name} and
-@var{key}.
-For this operation to succeed, both @var{NAME} and @var{KEY} @strong{must not}
-be registered already.
-The response JSON will contain two fields:
-@itemize @bullet
-@item error
-@item message
-@end itemize
-@code{error} can be either the string @code{"true"} or the string
-@code{"false"}: when @code{"true"}, it means the name could not be registered.
-Clients can get the reason of the failure from the HTTP response code or from
-the @code{message} field.
-@code{message} is a string which can be used by clients to let users know the
-result of the operation.  It might be localized to the daemon operator's
-locale.
-@end deffn
-@node Customizing the HTML output
-@subsubsection Customizing the HTML output
-In some situations, the daemon will serve HTML documents instead of JSON
-values.  It is possible to configure the daemon to serve custom documents
-instead of the ones provided with GNUnet, by setting the @code{HTMLDIR} value
-in its configuration to a directory path.
-Within the provided path, the daemon will search for these three files:
-@itemize @bullet
-@item fcfsd-index.html
-@item fcfsd-notfound.html
-@item fcfsd-forbidden.html
-@end itemize
-The @file{fcfsd-index.html} file is the daemon's ``homepage'': operators might
-want to provide information about the service here, or provide a form with
-which it is possible to register a name.
-The @file{fcfsd-notfound.html} file is used primarily to let users know they
-tried to access an unknown endpoint.
-The @file{fcfsd-forbidden.html} file is served to users when they try to
-access an endpoint they should not access.  For example, sending an invalid
-request might result in this page being served.
-@cindex GNS Namecache
-@node GNS Namecache
-@section GNS Namecache
-The NAMECACHE subsystem is responsible for caching (encrypted) resolution
-results of the GNU Name System (GNS). GNS makes zone information available
-to other users via the DHT. However, as accessing the DHT for every
-lookup is expensive (and as the DHT's local cache is lost whenever the
-peer is restarted), GNS uses the NAMECACHE as a more persistent cache for
-DHT lookups.
-Thus, instead of always looking up every name in the DHT, GNS first
-checks if the result is already available locally in the NAMECACHE.
-Only if there is no result in the NAMECACHE, GNS queries the DHT.
-The NAMECACHE stores data in the same (encrypted) format as the DHT.
-It thus makes no sense to iterate over all items in the
-NAMECACHE --- the NAMECACHE does not have a way to provide the keys
-required to decrypt the entries.
-Blocks in the NAMECACHE share the same expiration mechanism as blocks in
-the DHT --- the block expires wheneever any of the records in
-the (encrypted) block expires.
-The expiration time of the block is the only information stored in
-plaintext. The NAMECACHE service internally performs all of the required
-work to expire blocks, clients do not have to worry about this.
-Also, given that NAMECACHE stores only GNS blocks that local users
-requested, there is no configuration option to limit the size of the
-NAMECACHE. It is assumed to be always small enough (a few MB) to fit on
-the drive.
-The NAMECACHE supports the use of different database backends via a
-plugin API.
-@menu
-* libgnunetnamecache::
-* The NAMECACHE Client-Service Protocol::
-* The NAMECACHE Plugin API::
-@end menu
-@node libgnunetnamecache
-@subsection libgnunetnamecache
-The NAMECACHE API consists of five simple functions. First, there is
-@code{GNUNET_NAMECACHE_connect} to connect to the NAMECACHE service.
-This returns the handle required for all other operations on the
-NAMECACHE. Using @code{GNUNET_NAMECACHE_block_cache} clients can insert a
-block into the cache.
-@code{GNUNET_NAMECACHE_lookup_block} can be used to lookup blocks that
-were stored in the NAMECACHE. Both operations can be canceled using
-@code{GNUNET_NAMECACHE_cancel}. Note that canceling a
-@code{GNUNET_NAMECACHE_block_cache} operation can result in the block
-being stored in the NAMECACHE --- or not. Cancellation primarily ensures
-that the continuation function with the result of the operation will no
-longer be invoked.
-Finally, @code{GNUNET_NAMECACHE_disconnect} closes the connection to the
-NAMECACHE.
-The maximum size of a block that can be stored in the NAMECACHE is
-@code{GNUNET_NAMECACHE_MAX_VALUE_SIZE}, which is defined to be 63 kB.
-@node The NAMECACHE Client-Service Protocol
-@subsection The NAMECACHE Client-Service Protocol
-All messages in the NAMECACHE IPC protocol start with the
-@code{struct GNUNET_NAMECACHE_Header} which adds a request
-ID (32-bit integer) to the standard message header.
-The request ID is used to match requests with the
-respective responses from the NAMECACHE, as they are allowed to happen
-out-of-order.
-@menu
-* Lookup::
-* Store::
-@end menu
-@node Lookup
-@subsubsection Lookup
-The @code{struct LookupBlockMessage} is used to lookup a block stored in
-the cache.
-It contains the query hash. The NAMECACHE always responds with a
-@code{struct LookupBlockResponseMessage}. If the NAMECACHE has no
-response, it sets the expiration time in the response to zero.
-Otherwise, the response is expected to contain the expiration time, the
-ECDSA signature, the derived key and the (variable-size) encrypted data
-of the block.
-@node Store
-@subsubsection Store
-The @code{struct BlockCacheMessage} is used to cache a block in the
-NAMECACHE.
-It has the same structure as the @code{struct LookupBlockResponseMessage}.
-The service responds with a @code{struct BlockCacheResponseMessage} which
-contains the result of the operation (success or failure).
-In the future, we might want to make it possible to provide an error
-message as well.
-@node The NAMECACHE Plugin API
-@subsection The NAMECACHE Plugin API
-The NAMECACHE plugin API consists of two functions, @code{cache_block} to
-store a block in the database, and @code{lookup_block} to lookup a block
-in the database.
-@menu
-* Lookup2::
-* Store2::
-@end menu
-@node Lookup2
-@subsubsection Lookup2
-The @code{lookup_block} function is expected to return at most one block
-to the iterator, and return @code{GNUNET_NO} if there were no non-expired
-results.
-If there are multiple non-expired results in the cache, the lookup is
-supposed to return the result with the largest expiration time.
-@node Store2
-@subsubsection Store2
-The @code{cache_block} function is expected to try to store the block in
-the database, and return @code{GNUNET_SYSERR} if this was not possible
-for any reason.
-Furthermore, @code{cache_block} is expected to implicitly perform cache
-maintenance and purge blocks from the cache that have expired. Note that
-@code{cache_block} might encounter the case where the database already has
-another block stored under the same key. In this case, the plugin must
-ensure that the block with the larger expiration time is preserved.
-Obviously, this can done either by simply adding new blocks and selecting
-for the most recent expiration time during lookup, or by checking which
-block is more recent during the store operation.
-@cindex REVOCATION Subsystem
-@node REVOCATION Subsystem
-@section REVOCATION Subsystem
-The REVOCATION subsystem is responsible for key revocation of Egos.
-If a user learns that their private key has been compromised or has lost
-it, they can use the REVOCATION system to inform all of the other users
-that their private key is no longer valid.
-The subsystem thus includes ways to query for the validity of keys and to
-propagate revocation messages.
-@menu
-* Dissemination::
-* Revocation Message Design Requirements::
-* libgnunetrevocation::
-* The REVOCATION Client-Service Protocol::
-* The REVOCATION Peer-to-Peer Protocol::
-@end menu
-@node Dissemination
-@subsection Dissemination
-When a revocation is performed, the revocation is first of all
-disseminated by flooding the overlay network.
-The goal is to reach every peer, so that when a peer needs to check if a
-key has been revoked, this will be purely a local operation where the
-peer looks at its local revocation list. Flooding the network is also the
-most robust form of key revocation --- an adversary would have to control
-a separator of the overlay graph to restrict the propagation of the
-revocation message. Flooding is also very easy to implement --- peers that
-receive a revocation message for a key that they have never seen before
-simply pass the message to all of their neighbours.
-Flooding can only distribute the revocation message to peers that are
-online.
-In order to notify peers that join the network later, the revocation
-service performs efficient set reconciliation over the sets of known
-revocation messages whenever two peers (that both support REVOCATION
-dissemination) connect.
-The SET service is used to perform this operation efficiently.
-@node Revocation Message Design Requirements
-@subsection Revocation Message Design Requirements
-However, flooding is also quite costly, creating O(|E|) messages on a
-network with |E| edges.
-Thus, revocation messages are required to contain a proof-of-work, the
-result of an expensive computation (which, however, is cheap to verify).
-Only peers that have expended the CPU time necessary to provide
-this proof will be able to flood the network with the revocation message.
-This ensures that an attacker cannot simply flood the network with
-millions of revocation messages. The proof-of-work required by GNUnet is
-set to take days on a typical PC to compute; if the ability to quickly
-revoke a key is needed, users have the option to pre-compute revocation
-messages to store off-line and use instantly after their key has expired.
-Revocation messages must also be signed by the private key that is being
-revoked. Thus, they can only be created while the private key is in the
-possession of the respective user. This is another reason to create a
-revocation message ahead of time and store it in a secure location.
-@node libgnunetrevocation
-@subsection libgnunetrevocation
-The REVOCATION API consists of two parts, to query and to issue
-revocations.
-@menu
-* Querying for revoked keys::
-* Preparing revocations::
-* Issuing revocations::
-@end menu
-@node Querying for revoked keys
-@subsubsection Querying for revoked keys
-@code{GNUNET_REVOCATION_query} is used to check if a given ECDSA public
-key has been revoked.
-The given callback will be invoked with the result of the check.
-The query can be canceled using @code{GNUNET_REVOCATION_query_cancel} on
-the return value.
-@node Preparing revocations
-@subsubsection Preparing revocations
-It is often desirable to create a revocation record ahead-of-time and
-store it in an off-line location to be used later in an emergency.
-This is particularly true for GNUnet revocations, where performing the
-revocation operation itself is computationally expensive and thus is
-likely to take some time.
-Thus, if users want the ability to perform revocations quickly in an
-emergency, they must pre-compute the revocation message.
-The revocation API enables this with two functions that are used to
-compute the revocation message, but not trigger the actual revocation
-operation.
-@code{GNUNET_REVOCATION_check_pow} should be used to calculate the
-proof-of-work required in the revocation message. This function takes the
-public key, the required number of bits for the proof of work (which in
-GNUnet is a network-wide constant) and finally a proof-of-work number as
-arguments.
-The function then checks if the given proof-of-work number is a valid
-proof of work for the given public key. Clients preparing a revocation
-are expected to call this function repeatedly (typically with a
-monotonically increasing sequence of numbers of the proof-of-work number)
-until a given number satisfies the check.
-That number should then be saved for later use in the revocation
-operation.
-@code{GNUNET_REVOCATION_sign_revocation} is used to generate the
-signature that is required in a revocation message.
-It takes the private key that (possibly in the future) is to be revoked
-and returns the signature.
-The signature can again be saved to disk for later use, which will then
-allow performing a revocation even without access to the private key.
-@node Issuing revocations
-@subsubsection Issuing revocations
-Given a ECDSA public key, the signature from @code{GNUNET_REVOCATION_sign}
-and the proof-of-work,
-@code{GNUNET_REVOCATION_revoke} can be used to perform the
-actual revocation. The given callback is called upon completion of the
-operation. @code{GNUNET_REVOCATION_revoke_cancel} can be used to stop the
-library from calling the continuation; however, in that case it is
-undefined whether or not the revocation operation will be executed.
-@node The REVOCATION Client-Service Protocol
-@subsection The REVOCATION Client-Service Protocol
-The REVOCATION protocol consists of four simple messages.
-A @code{QueryMessage} containing a public ECDSA key is used to check if a
-particular key has been revoked. The service responds with a
-@code{QueryResponseMessage} which simply contains a bit that says if the
-given public key is still valid, or if it has been revoked.
-The second possible interaction is for a client to revoke a key by passing a
-@code{RevokeMessage} to the service. The @code{RevokeMessage} contains the
-ECDSA public key to be revoked, a signature by the corresponding private key
-and the proof-of-work. The service responds with a
-@code{RevocationResponseMessage} which can be used to indicate that the
-@code{RevokeMessage} was invalid (e.g. the proof of work is incorrect), or
-otherwise to indicate that the revocation has been processed successfully.
-@node The REVOCATION Peer-to-Peer Protocol
-@subsection The REVOCATION Peer-to-Peer Protocol
-Revocation uses two disjoint ways to spread revocation information among
-peers.
-First of all, P2P gossip exchanged via CORE-level neighbours is used to
-quickly spread revocations to all connected peers.
-Second, whenever two peers (that both support revocations) connect,
-the SET service is used to compute the union of the respective revocation
-sets.
-In both cases, the exchanged messages are @code{RevokeMessage}s which
-contain the public key that is being revoked, a matching ECDSA signature,
-and a proof-of-work.
-Whenever a peer learns about a new revocation this way, it first
-validates the signature and the proof-of-work, then stores it to disk
-(typically to a file $GNUNET_DATA_HOME/revocation.dat) and finally
-spreads the information to all directly connected neighbours.
-For computing the union using the SET service, the peer with the smaller
-hashed peer identity will connect (as a "client" in the two-party set
-protocol) to the other peer after one second (to reduce traffic spikes
-on connect) and initiate the computation of the set union.
-All revocation services use a common hash to identify the SET operation
-over revocation sets.
-The current implementation accepts revocation set union operations from
-all peers at any time; however, well-behaved peers should only initiate
-this operation once after establishing a connection to a peer with a
-larger hashed peer identity.
-@cindex FS
-@cindex FS Subsystem
-@node File-sharing (FS) Subsystem
-@section File-sharing (FS) Subsystem
-This chapter describes the details of how the file-sharing service works.
-As with all services, it is split into an API (libgnunetfs), the service
-process (gnunet-service-fs) and user interface(s).
-The file-sharing service uses the datastore service to store blocks and
-the DHT (and indirectly datacache) for lookups for non-anonymous
-file-sharing.
-Furthermore, the file-sharing service uses the block library (and the
-block fs plugin) for validation of DHT operations.
-In contrast to many other services, libgnunetfs is rather complex since
-the client library includes a large number of high-level abstractions;
-this is necessary since the Fs service itself largely only operates on
-the block level.
-The FS library is responsible for providing a file-based abstraction to
-applications, including directories, meta data, keyword search,
-verification, and so on.
-The method used by GNUnet to break large files into blocks and to use
-keyword search is called the
-"Encoding for Censorship Resistant Sharing" (ECRS).
-ECRS is largely implemented in the fs library; block validation is also
-reflected in the block FS plugin and the FS service.
-ECRS on-demand encoding is implemented in the FS service.
-NOTE: The documentation in this chapter is quite incomplete.
-@menu
-* Encoding for Censorship-Resistant Sharing (ECRS)::
-* File-sharing persistence directory structure::
-@end menu
-@cindex ECRS
-@cindex Encoding for Censorship-Resistant Sharing
-@node Encoding for Censorship-Resistant Sharing (ECRS)
-@subsection Encoding for Censorship-Resistant Sharing (ECRS)
-When GNUnet shares files, it uses a content encoding that is called ECRS,
-the Encoding for Censorship-Resistant Sharing.
-Most of ECRS is described in the (so far unpublished) research paper
-attached to this page. ECRS obsoletes the previous ESED and ESED II
-encodings which were used in GNUnet before version 0.7.0.
-The rest of this page assumes that the reader is familiar with the
-attached paper. What follows is a description of some minor extensions
-that GNUnet makes over what is described in the paper.
-The reason why these extensions are not in the paper is that we felt
-that they were obvious or trivial extensions to the original scheme and
-thus did not warrant space in the research report.
-@menu
-* Namespace Advertisements::
-* KSBlocks::
-@end menu
-@node Namespace Advertisements
-@subsubsection Namespace Advertisements
-@c %**FIXME: all zeroses -> ?
-An @code{SBlock} with identifier all zeros is a signed
-advertisement for a namespace. This special @code{SBlock} contains
-metadata describing the content of the namespace.
-Instead of the name of the identifier for a potential update, it contains
-the identifier for the root of the namespace.
-The URI should always be empty. The @code{SBlock} is signed with the
-content provider's RSA private key (just like any other SBlock). Peers
-can search for @code{SBlock}s in order to find out more about a namespace.
-@node KSBlocks
-@subsubsection KSBlocks
-GNUnet implements @code{KSBlocks} which are @code{KBlocks} that, instead
-of encrypting a CHK and metadata, encrypt an @code{SBlock} instead.
-In other words, @code{KSBlocks} enable GNUnet to find @code{SBlocks}
-using the global keyword search.
-Usually the encrypted @code{SBlock} is a namespace advertisement.
-The rationale behind @code{KSBlock}s and @code{SBlock}s is to enable
-peers to discover namespaces via keyword searches, and, to associate
-useful information with namespaces. When GNUnet finds @code{KSBlocks}
-during a normal keyword search, it adds the information to an internal
-list of discovered namespaces. Users looking for interesting namespaces
-can then inspect this list, reducing the need for out-of-band discovery
-of namespaces.
-Naturally, namespaces (or more specifically, namespace advertisements) can
-also be referenced from directories, but @code{KSBlock}s should make it
-easier to advertise namespaces for the owner of the pseudonym since they
-eliminate the need to first create a directory.
-Collections are also advertised using @code{KSBlock}s.
-@c https://old.gnunet.org/sites/default/files/ecrs.pdf
-@node File-sharing persistence directory structure
-@subsection File-sharing persistence directory structure
-This section documents how the file-sharing library implements
-persistence of file-sharing operations and specifically the resulting
-directory structure.
-This code is only active if the @code{GNUNET_FS_FLAGS_PERSISTENCE} flag
-was set when calling @code{GNUNET_FS_start}.
-In this case, the file-sharing library will try hard to ensure that all
-major operations (searching, downloading, publishing, unindexing) are
-persistent, that is, can live longer than the process itself.
-More specifically, an operation is supposed to live until it is
-explicitly stopped.
-If @code{GNUNET_FS_stop} is called before an operation has been stopped, a
-@code{SUSPEND} event is generated and then when the process calls
-@code{GNUNET_FS_start} next time, a @code{RESUME} event is generated.
-Additionally, even if an application crashes (segfault, SIGKILL, system
-crash) and hence @code{GNUNET_FS_stop} is never called and no
-@code{SUSPEND} events are generated, operations are still resumed (with
-@code{RESUME} events).
-This is implemented by constantly writing the current state of the
-file-sharing operations to disk.
-Specifically, the current state is always written to disk whenever
-anything significant changes (the exception are block-wise progress in
-publishing and unindexing, since those operations would be slowed down
-significantly and can be resumed cheaply even without detailed
-accounting).
-Note that if the process crashes (or is killed) during a serialization
-operation, FS does not guarantee that this specific operation is
-recoverable (no strict transactional semantics, again for performance
-reasons). However, all other unrelated operations should resume nicely.
-Since we need to serialize the state continuously and want to recover as
-much as possible even after crashing during a serialization operation,
-we do not use one large file for serialization.
-Instead, several directories are used for the various operations.
-When @code{GNUNET_FS_start} executes, the master directories are scanned
-for files describing operations to resume.
-Sometimes, these operations can refer to related operations in child
-directories which may also be resumed at this point.
-Note that corrupted files are cleaned up automatically.
-However, dangling files in child directories (those that are not
-referenced by files from the master directories) are not automatically
-removed.
-Persistence data is kept in a directory that begins with the "STATE_DIR"
-prefix from the configuration file
-(by default, "$SERVICEHOME/persistence/") followed by the name of the
-client as given to @code{GNUNET_FS_start} (for example, "gnunet-gtk")
-followed by the actual name of the master or child directory.
-The names for the master directories follow the names of the operations:
-@itemize @bullet
-@item "search"
-@item "download"
-@item "publish"
-@item "unindex"
-@end itemize
-Each of the master directories contains names (chosen at random) for each
-active top-level (master) operation.
-Note that a download that is associated with a search result is not a
-top-level operation.
-In contrast to the master directories, the child directories are only
-consulted when another operation refers to them.
-For each search, a subdirectory (named after the master search
-synchronization file) contains the search results.
-Search results can have an associated download, which is then stored in
-the general "download-child" directory.
-Downloads can be recursive, in which case children are stored in
-subdirectories mirroring the structure of the recursive download
-(either starting in the master "download" directory or in the
-"download-child" directory depending on how the download was initiated).
-For publishing operations, the "publish-file" directory contains
-information about the individual files and directories that are part of
-the publication.
-However, this directory structure is flat and does not mirror the
-structure of the publishing operation.
-Note that unindex operations cannot have associated child operations.
-@cindex REGEX subsystem
-@node REGEX Subsystem
-@section REGEX Subsystem
-Using the REGEX subsystem, you can discover peers that offer a particular
-service using regular expressions.
-The peers that offer a service specify it using a regular expressions.
-Peers that want to patronize a service search using a string.
-The REGEX subsystem will then use the DHT to return a set of matching
-offerers to the patrons.
-For the technical details, we have Max's defense talk and Max's Master's
-thesis.
-@c An additional publication is under preparation and available to
-@c team members (in Git).
-@c FIXME: Where is the file? Point to it. Assuming that it's szengel2012ms
-@menu
-* How to run the regex profiler::
-@end menu
-@node How to run the regex profiler
-@subsection How to run the regex profiler
-The gnunet-regex-profiler can be used to profile the usage of mesh/regex
-for a given set of regular expressions and strings.
-Mesh/regex allows you to announce your peer ID under a certain regex and
-search for peers matching a particular regex using a string.
-See @uref{https://bib.gnunet.org/full/date.html#2012_5f2, szengel2012ms} for a full
-introduction.
-First of all, the regex profiler uses GNUnet testbed, thus all the
-implications for testbed also apply to the regex profiler
-(for example you need password-less ssh login to the machines listed in
-your hosts file).
-@strong{Configuration}
-Moreover, an appropriate configuration file is needed.
-In the following paragraph the important details are highlighted.
-Announcing of the regular expressions is done by the
-gnunet-daemon-regexprofiler, therefore you have to make sure it is
-started, by adding it to the START_ON_DEMAND set of ARM:
-@example
-[regexprofiler]
-START_ON_DEMAND = YES
-@end example
-@noindent
-Furthermore you have to specify the location of the binary:
-@example
-[regexprofiler]
-# Location of the gnunet-daemon-regexprofiler binary.
-BINARY = /home/szengel/gnunet/src/mesh/.libs/gnunet-daemon-regexprofiler
-# Regex prefix that will be applied to all regular expressions and
-# search string.
-REGEX_PREFIX = "GNVPN-0001-PAD"
-@end example
-@noindent
-When running the profiler with a large scale deployment, you probably
-want to reduce the workload of each peer.
-Use the following options to do this.
-@example
-[dht]
-# Force network size estimation
-FORCE_NSE = 1
-[dhtcache]
-DATABASE = heap
-# Disable RC-file for Bloom filter? (for benchmarking with limited IO
-# availability)
-DISABLE_BF_RC = YES
-# Disable Bloom filter entirely
-DISABLE_BF = YES
-[nse]
-# Minimize proof-of-work CPU consumption by NSE
-WORKBITS = 1
-@end example
-@noindent
-@strong{Options}
-To finally run the profiler some options and the input data need to be
-specified on the command line.
-@example
-gnunet-regex-profiler -c config-file -d log-file -n num-links \
-p path-compression-length -s search-delay -t matching-timeout \
-a num-search-strings hosts-file policy-dir search-strings-file
-@end example
-@noindent
-Where...
-@itemize @bullet
-@item ... @code{config-file} means the configuration file created earlier.
-@item ... @code{log-file} is the file where to write statistics output.
-@item ... @code{num-links} indicates the number of random links between
-started peers.
-@item ... @code{path-compression-length} is the maximum path compression
-length in the DFA.
-@item ... @code{search-delay} time to wait between peers finished linking
-and starting to match strings.
-@item ... @code{matching-timeout} timeout after which to cancel the
-searching.
-@item ... @code{num-search-strings} number of strings in the
-search-strings-file.
-@item ... the @code{hosts-file} should contain a list of hosts for the
-testbed, one per line in the following format:
-@itemize @bullet
-@item @code{user@@host_ip:port}
-@end itemize
-@item ... the @code{policy-dir} is a folder containing text files
-containing one or more regular expressions. A peer is started for each
-file in that folder and the regular expressions in the corresponding file
-are announced by this peer.
-@item ... the @code{search-strings-file} is a text file containing search
-strings, one in each line.
-@end itemize
-@noindent
-You can create regular expressions and search strings for every AS in the
-Internet using the attached scripts. You need one of the
-@uref{http://data.caida.org/datasets/routing/routeviews-prefix2as/, CAIDA routeviews prefix2as}
-data files for this. Run
-@example
-create_regex.py <filename> <output path>
-@end example
-@noindent
-to create the regular expressions and
-@example
-create_strings.py <input path> <outfile>
-@end example
-@noindent
-to create a search strings file from the previously created
-regular expressions.
-@cindex REST subsystem
-@node REST Subsystem
-@section REST Subsystem
-Using the REST subsystem, you can expose REST-based APIs or services.
-The REST service is designed as a pluggable architecture.
-To create a new REST endpoint, simply add a library in the form
-``plugin_rest_*''.
-The REST service will automatically load all REST plugins on startup.
-@strong{Configuration}
-The REST service can be configured in various ways.
-The reference config file can be found in
-@file{src/rest/rest.conf}:
-@example
-[rest]
-REST_PORT=7776
-REST_ALLOW_HEADERS=Authorization,Accept,Content-Type
-REST_ALLOW_ORIGIN=*
-REST_ALLOW_CREDENTIALS=true
-@end example
-The port as well as
-@deffn{cross-origin resource sharing} (CORS)
-@end deffn
-headers that are supposed to be advertised by the rest service are
-configurable.
-@menu
-* Namespace considerations::
-* Endpoint documentation::
-@end menu
-@node Namespace considerations
-@subsection Namespace considerations
-The @command{gnunet-rest-service} will load all plugins that are installed.
-As such it is important that the endpoint namespaces do not clash.
-For example, plugin X might expose the endpoint ``/xxx'' while plugin Y
-exposes endpoint ``/xxx/yyy''.
-This is a problem if plugin X is also supposed to handle a call
-to ``/xxx/yyy''.
-Currently the REST service will not complain or warn about such clashes,
-so please make sure that endpoints are unambiguous.
-@node Endpoint documentation
-@subsection Endpoint documentation
-This is WIP. Endpoints should be documented appropriately.
-Preferably using annotations.
-@cindex RPS Subsystem
-@node RPS Subsystem
-@section RPS Subsystem
-In literature, Random Peer Sampling (RPS) refers to the problem of
-reliably@footnote{"Reliable" in this context means having no bias,
-neither spatial, nor temporal, nor through malicious activity.} drawing
-random samples from an unstructured p2p network.
-Doing so in a reliable manner is not only hard because of inherent
-problems but also because of possible malicious peers that could try to
-bias the selection.
-It is useful for all kind of gossip protocols that require the selection
-of random peers in the whole network like gathering statistics,
-spreading and aggregating information in the network, load balancing and
-overlay topology management.
-The approach chosen in the RPS service implementation in GNUnet follows
-the @uref{https://bib.gnunet.org/full/date.html\#2009_5f0, Brahms}
-design.
-The current state is "work in progress". There are a lot of things that
-need to be done, primarily finishing the experimental evaluation and a
-re-design of the API.
-The abstract idea is to subscribe to connect to/start the RPS service
-and request random peers that will be returned when they represent a
-random selection from the whole network with high probability.
-An additional feature to the original Brahms-design is the selection of
-sub-groups: The GNUnet implementation of RPS enables clients to ask for
-random peers from a group that is defined by a common shared secret.
-(The secret could of course also be public, depending on the use-case.)
-Another addition to the original protocol was made: The sampler
-mechanism that was introduced in Brahms was slightly adapted and used to
-actually sample the peers and returned to the client.
-This is necessary as the original design only keeps peers connected to
-random other peers in the network. In order to return random peers to
-client requests independently random, they cannot be drawn from the
-connected peers.
-The adapted sampler makes sure that each request for random peers is
-independent from the others.
-@menu
-* Brahms::
-@end menu
-@node Brahms
-@subsection Brahms
-The high-level concept of Brahms is two-fold: Combining push-pull gossip
-with locally fixing a assumed bias using cryptographic min-wise
-permutations.
-The central data structure is the view - a peer's current local sample.
-This view is used to select peers to push to and pull from.
-This simple mechanism can be biased easily. For this reason Brahms
-'fixes' the bias by using the so-called sampler. A data structure that
-takes a list of elements as input and outputs a random one of them
-independently of the frequency in the input set. Both an element that
-was put into the sampler a single time and an element that was put into
-it a million times have the same probability of being the output.
-This is achieved with exploiting min-wise independent
-permutations.
-In the RPS service we use HMACs: On the initialisation of a sampler
-element, a key is chosen at random. On each input the HMAC with the
-random key is computed. The sampler element keeps the element with the
-minimal HMAC.
-In order to fix the bias in the view, a fraction of the elements in the
-view are sampled through the sampler from the random stream of peer IDs.
-According to the theoretical analysis of Bortnikov et al. this suffices
-to keep the network connected and having random peers in the view.
-@cindex TRANSPORT-NG Subsystem
-@node TRANSPORT-NG Subsystem
-@section TRANSPORT-NG Subsystem
-The current GNUnet TRANSPORT architecture is rooted in the GNUnet 0.4 design
-of using plugins for the actual transmission operations and the ATS subsystem
-to select a plugin and allocate bandwidth. The following key issues have been
-identified with this design:
-@itemize @bullet
-@item Bugs in one plugin can affect the TRANSPORT service and other plugins.
-      There is at least one open bug that affects sockets, where the origin is
-      difficult to pinpoint due to the large code base.
-@item Relevant operating system default configurations often impose a limit of
-      1024 file descriptors per process. Thus, one plugin may impact other
-      plugin's connectivity choices.
-@item Plugins are required to offer bi-directional connectivity. However,
-      firewalls (incl. NAT boxes) and physical environments sometimes only
-      allow uni-directional connectivity, which then currently cannot be
-      utilized at all.
-@item Distance vector routing was implemented in 209 but shortly afterwards
-      broken and due to the complexity of implementing it as a plugin and
-      dealing with the resource allocation consequences was never useful.
-@item Most existing plugins communicate completely using cleartext, exposing
-      metad data (message size) and making it easy to fingerprint and
-      possibly block GNUnet traffic.
-@item Various NAT traversal methods are not supported.
-@item The service logic is cluttered with "manipulation" support code for
-      TESTBED to enable faking network characteristics like lossy connections
-      or firewewalls.
-@item Bandwidth allocation is done in ATS, requiring the duplication of state
-      and resulting in much delayed allocation decisions. As a result,
-      often available bandwidth goes unused. Users are expected to manually
-      configure bandwidth limits, instead of TRANSPORT using congestion control
-      to adapt automatically.
-@item TRANSPORT is difficult to test and has bad test coverage.
-@item HELLOs include an absolute expiration time. Nodes with unsynchronized
-      clocks cannot connect.
-@item Displaying the contents of a HELLO requires the respective plugin as the
-      plugin-specific data is encoded in binary. This also complicates logging.
-@end itemize
-@menu
-* Design goals of TNG::
-* HELLO-NG::
-* Priorities and preferences::
-* Communicators::
-@end menu
-@node Design goals of TNG
-@subsection Design goals of TNG
-In order to address the above issues, we want to:
-@itemize @bullet
-@item Move plugins into separate processes which we shall call
-      @emph{communicators}. Communicators connect as clients to the transport
-      service.
-@item TRANSPORT should be able to utilize any number of communcators to the
-      same peer at the same time.
-@item TRANSPORT should be responsible for fragmentation, retransmission,
-      flow- and congestion-control. Users should no longer have to configure
-      bandwidth limits: TRANSPORT should detect what is available and use it.
-@item Commnunicators should be allowed to be uni-directional and unreliable.
-      TRANSPORT shall create bi-directional channels from this whenever
-      possible.
-@item DV should no longer be a plugin, but part of TRANSPORT.
-@item TRANSPORT should provide communicators help communicating, for example
-      in the case of uni-directional communicators or the need for out-of-band
-      signalling for NAT traversal. We call this functionality
-      @emph{backchannels}.
-@item Transport manipulation should be signalled to CORE on a per-message basis
-      instead of an approximate bandwidth.
-@item CORE should signal performance requirements (reliability, latency, etc.)
-      on a per-message basis to TRANSPORT. If possible, TRANSPORT should
-      consider those options when scheduling messages for transmission.
-@item HELLOs should be in a humman-readable format with monotonic time
-      expirations.
-@end itemize
-The new architecture is planned as follows:
-@image{images/tng,5in,,TNG architecture.}
-TRANSPORT's main objective is to establish bi-directional virtual links using a
-variety of possibly uni-directional communicators. Links undergo the following
-steps:
-@enumerate
-@item Communicator informs TRANSPORT A that a queue (direct neighbour) is
-      available, or equivalently TRANSPORT A discovers a (DV) path to a target
-      B.
-@item TRANSPORT A sends a challenge to the target peer, trying to confirm that
-      the peer can receive. FIXME: This is not implemented properly for DV.
-      Here we should really take a validated DVH and send a challenge exactly
-      down that path!
-@item The other TRANSPORT, TRANSPORT B, receives the challenge, and sends back
-      a response, possibly using a dierent path. If TRANSPORT B does not yet
-      have a virtual link to A, it must try to establish a virtual link.
-@item Upon receiving the response, TRANSPORT A creates the virtual link. If the
-      response included a challenge, TRANSPORT A must respond to this challenge
-      as well, eectively re-creating the TCP 3-way handshake (just with longer
-      challenge values).
-@end enumerate
-@node HELLO-NG
-@subsection HELLO-NG
-HELLOs change in three ways. First of all, communicators encode the respective
-addresses in a human-readable URL-like string. This way, we do no longer
-require the communicator to print the contents of a HELLO.
-Second, HELLOs no longer contain an expiration time, only a creation time.
-The receiver must only compare the respective absolute values. So given a HELLO
-from the same sender with a larger creation time, then the old one is no longer
-valid. This also obsoletes the need for the gnunet-hello binary to set HELLO
-expiration times to never.
-Third, a peer no longer generates one big HELLO that always contains all of the
-addresses. Instead, each address is signed individually and shared only over
-the address scopes where it makes sense to share the address. In particular,
-care should be taken to not share MACs across the Internet and confine their
-use to the LAN.
-As each address is signed separately, having multiple addresses valid at the
-same time (given the new creation time expiration logic) requires that those
-addresses must have exactly the same creation time.
-Whenever that monotonic time is increased, all addresses must be re-signed and
-re-distributed.
-@node Priorities and preferences
-@subsection Priorities and preferences
-In the new design, TRANSPORT adopts a feature (which was previously already
-available in CORE) of the MQ API to allow applications to specify priorities and
-preferences per message (or rather, per MQ envelope).
-The (updated) MQ API allows applications to specify one of four priority levels
-as well as desired preferences for transmission by setting options on an
-envelope. These preferences currently are:
-@itemize @bullet
-@item GNUNET_MQ_PREF_UNRELIABLE: Disables TRANSPORT waiting for ACKS on
-      unreliable channels like UDP. Now it is fire and forget. These messages
-      then cannot be used for RTT estimates either.
-@item GNUNET_MQ_PREF_LOW_LATENCY: Directs TRANSPORT to select the
-      lowest-latency transmission choices possible.
-@item GNUNET_MQ_PREF_CORK_ALLOWED: Allows TRANSPORT to delay transmission to
-      group the message with other messages into a larger batch to reduce the
-      number of packets sent.
-@item GNUNET_MQ_PREF_GOODPUT: Directs TRANSPORT to select the highest goodput
-      channel available.
-@item GNUNET_MQ_PREF_OUT_OF_ORDER: Allows TRANSPORT to reorder the messages as
-      it sees fit, otherwise TRANSPORT should attempt to preserve transmission
-      order.
-@end itemize
-Each MQ envelope is always able to store those options (and the priority), and
-in the future this uniform API will be used by TRANSPORT, CORE, CADET and
-possibly other subsystems that send messages (like LAKE).
-When CORE sets preferences and priorities, it is supposed to respect the
-preferences and priorities it is given from higher layers. Similarly, CADET also
-simply passes on the preferences and priorities of the layer above CADET. When a
-layer combines multiple smaller messages into one larger transmission, the
-@code{GNUNET_MQ_env_combine_options()} should be used to calculate options for
-the combined message. We note that the exact semantics of the options may differ
-by layer. For example, CADET will always strictly implement reliable and
-in-order delivery of messages, while the same options are only advisory for
-TRANSPORT and CORE: they should try (using ACKs on unreliable communicators,
-not changing the message order themselves), but if messages are lost anyway
-(e.g. because a TCP is dropped in the middle), or if messages are reordered
-(e.g. because they took different paths over the network and arrived in a
-different order) TRANSPORT and CORE do not have to correct this. Whether a
-preference is strict or loose is thus dened by the respective layer.
-@node Communicators
-@subsection Communicators
-The API for communicators is defined in
-@code{gnunet_transport_communication_service.h}.
-Each communicator must specify its (global) communication characteristics, which
-for now only say whether the communication is reliable (e.g. TCP, HTTPS) or
-unreliable (e.g. UDP, WLAN). Each communicator must specify a unique address
-prex, or NULL if the communicator cannot establish outgoing connections
-(for example because it is only acting as a TCP server).
-A communicator must tell TRANSPORT which addresses it is reachable under.
-Addresses may be added or removed at any time. A communicator may have zero
-addresses (transmission only).
-Addresses do not have to match the address prefix.
-TRANSPORT may ask a communicator to try to connect to another address.
-TRANSPORT will only ask for connections where the address matches the
-communicator's address prefix that was provided when the connection was
-established. Communicators should then attempt to establish a connection.
-No response is provided to TRANSPORT service on failure. The TRANSPORT service
-has to ask the communicator explicitly to retry.
-If a communicator succeeds in establishing an outgoing connection for
-transmission, or if a communicator receives an incoming bi-directional
-connection, the communicator must inform the TRANSPORT service that a message
-queue (MQ) for transmission is now available. For that MQ, the communicator must
-provide the peer identity claimed by the other end, a human-readable address
-(for debugging) and a maximum transfer unit (MTU). A MTU of zero means sending
-is not supported, SIZE_MAX should be used for no MTU. The communicator should
-also tell TRANSPORT what network type is used for the queue. The communicator
-may tell TRANSPORT anytime that the queue was deleted and is no longer
-available.
-The communicator API also provides for flow control. First, communicators
-exhibit back-pressure on TRANSPORT: the number of messages TRANSPORT may add to
-a queue for transmission will be limited. So by not draining the transmission
-queue, back-pressure is provided to TRANSPORT. In the other direction,
-communicators may allow TRANSPORT to give back-pressure towards the
-communicator by providing a non-NULL
-@code{GNUNET_TRANSPORT_MessageCompletedCallback}
-argument to the @code{GNUNET_TRANSPORT_communicator_receive} function. In this
-case, TRANSPORT will only invoke this function once it has processed the message
-and is ready to receive more. Communicators should then limit how much traffic
-they receive based on this backpressure. Note that communicators do not have to
-provide a @code{GNUNET_TRANSPORT_MessageCompletedCallback};
-for example, UDP cannot support back-pressure due to the nature of the UDP
-protocol. In this case, TRANSPORT will implement its own TRANSPORT-to-TRANSPORT
-flow control to reduce the sender's data rate to acceptable levels.
-TRANSPORT may notify a communicator about backchannel messages TRANSPORT
-received from other peers for this communicator. Similarly, communicators can
-ask TRANSPORT to try to send a backchannel message to other communicators of
-other peers. The semantics of the backchannel message are up to the
-communicators which use them.
-TRANSPORT may fail transmitting backchannel messages, and TRANSPORT will not
-attempt to retransmit them.
-@cindex MESSENGER Subsystem
-@cindex MESSENGER
-@cindex messenger
-@node MESSENGER Subsystem
-@section MESSENGER Subsystem
-The MESSENGER subsystem is responsible for secure end-to-end communication in
-groups of nodes in the GNUnet overlay network. MESSENGER builds on the CADET
-subsystem which provides a reliable and secure end-to-end communication between
-the nodes inside of these groups.
-Additionally to the CADET security benefits, MESSENGER provides following
-properties designed for application level usage:
-@itemize @bullet
-@item MESSENGER provides integrity by signing the messages with the users
-      provided ego
-@item MESSENGER adds (optional) forward secrecy by replacing the key pair of the
-      used ego and signing the propagation of the new one with old one (chaining
-      egos)
-@item MESSENGER provides verification of a original sender by checking against
-      all used egos from a member which are currently in active use (active use
-      depends on the state of a member session)
-@item MESSENGER offsers (optional) decentralized message forwarding between all
-      nodes in a group to improve availability and prevent MITM-attacks
-@item MESSENGER handles new connections and disconnections from nodes in the
-      group by reconnecting them preserving an efficient structure for message
-      distribution (ensuring availability and accountablity)
-@item MESSENGER provides replay protection (messages can be uniquely identified
-      via SHA-512, include a timestamp and the hash of the last message)
-@item MESSENGER allows detection for dropped messages by chaining them (messages
-      refer to the last message by their hash) improving accountability
-@item MESSENGER allows requesting messages from other peers explicitly to ensure
-      availability
-@item MESSENGER provides confidentiality by padding messages to few different
-      sizes (512 bytes, 4096 bytes, 32768 bytes and maximal message size from
-      CADET)
-@item MESSENGER adds (optional) confidentiality with ECDHE to exchange and use
-      symmetric encryption, encrypting with both AES-256 and Twofish but
-      allowing only selected members to decrypt (using the receivers ego for
-      ECDHE)
-@end itemize
-Also MESSENGER provides multiple features with privacy in mind:
-@itemize @bullet
-@item MESSENGER allows deleting messages from all peers in the group by the
-      original sender (uses the MESSENGER provided verification)
-@item MESSENGER allows using the publicly known anonymous ego instead of any
-      unique identifying ego
-@item MESSENGER allows your node to decide between acting as relay of the used
-      messaging room (sharing your peer's identity with all nodes in the group)
-      or acting as guest (sharing your peer's identity only with the nodes you
-      explicitly open a connection to)
-@item MESSENGER handles members independently of the peer's identity making
-      forwarded messages indistinguishable from directly received ones (
-      complicating the tracking of messages and identifying its origin)
-@item MESSENGER allows names of members being not unique (also names are
-      optional)
-@item MESSENGER does not include information about the selected receiver of an
-      explicitly encrypted message in its header, complicating it for other
-      members to draw conclusions from communication partners
-@end itemize
-@menu
-* libgnunetmessenger::
-* Member sessions::
-@end menu
-@node libgnunetmessenger
-@subsection libgnunetmessenger
-The MESSENGER API (defined in @file{gnunet_messenger_service.h}) allows P2P
-applications built using GNUnet to communicate with specified kinds of messages
-in a group. It provides applications the ability to send and receive encrypted
-messages to any group of peers participating in GNUnet in a decentralized way (
-without even knowing all peers's identities).
-MESSENGER delivers messages to other peers in "rooms". A room uses a variable
-amount of CADET "channels" which will all be used for message distribution. Each
-channel can represent an outgoing connection opened by entering a room with
-@code{GNUNET_MESSENGER_enter_room} or an incoming connection if the room was
-opened before via @code{GNUNET_MESSENGER_open_room}.
-@image{images/messenger_room,6in,,Room structure}
-To enter a room you have to specify the "door" (peer's identity of a peer which
-has opened the room) and the key of the room (which is identical to a CADET
-"port"). To open a room you have to specify only the key to use. When opening a
-room you automatically distribute a PEER-message sharing your peer's identity in
-the room.
-Entering or opening a room can also be combined in any order. In any case you
-will automatically get a unique member ID and send a JOIN-message notifying
-others about your entry and your public key from your selected ego.
-The ego can be selected by name with the initial @code{GNUNET_MESSENGER_connect}
-besides setting a (identity-)callback for each change/confirmation of the used
-ego and a (message-)callback which gets called every time a message gets sent or
-received in the room. Once the identity-callback got called you can check your
-used ego with @code{GNUNET_MESSENGER_get_key} providing only its public key. The
-function returns NULL if the anonymous ego is used. If the ego should be
-replaced with a newly generated one, you can use @code{GNUNET_MESSENGER_update}
-to ensure proper chaining of used egos.
-Also once the identity-callback got called you can check your used name with
-@code{GNUNET_MESSENGER_get_name} and potentially change or set a name via
-@code{GNUNET_MESSENGER_set_name}. A name is for example required to create a new
-ego with @code{GNUNET_MESSENGER_update}. Also any change in ego or name will
-automatically be distributed in the room with a NAME- or KEY-message
-respectively.
-To send a message a message inside of a room you can use
-@code{GNUNET_MESSENGER_send_message}. If you specify a selected contact as
-receiver, the message gets encrypted automatically and will be sent as PRIVATE-
-message instead.
-To request a potentially missed message or to get a specific message after its
-original call of the message-callback, you can use
-@code{GNUNET_MESSENGER_get_message}. Additionally once a message was distributed
-to application level and the message-callback got called, you can get the
-contact respresenting a message's sender respectively with
-@code{GNUNET_MESSENGER_get_sender}. This allows getting name and the public key
-of any sender currently in use with @code{GNUNET_MESSENGER_contact_get_name}
-and @code{GNUNET_MESSENGER_contact_get_key}. It is also possible to iterate
-through all current members of a room with
-@code{GNUNET_MESSENGER_iterate_members} using a callback.
-To leave a room you can use @code{GNUNET_MESSENGER_close_room} which will also
-close the rooms connections once all applications on the same peer have left
-the room. Leaving a room will also send a LEAVE-message closing a member session
-on all connected peers before any connection will be closed. Leaving a room is
-however not required for any application to keep your member session open
-between multiple sessions of the actual application.
-Finally, when an application no longer wants to use CADET, it should call
-@code{GNUNET_MESSENGER_disconnect}. You don't have to explicitly close the used
-rooms or leave them.
-Here is a little summary to the kinds of messages you can send manually:
-@menu
-* MERGE-message::
-* INVITE-message::
-* TEXT-message::
-* FILE-message::
-* DELETE-message::
-@end menu
-@node MERGE-message
-@subsubsection MERGE-message
-MERGE-messages will generally be sent automatically to reduce the amount of
-parallel chained messages. This is necessary to close a member session for
-example. You can also send MERGE-messages manually if required to merge two
-chains of messages.
-@node INVITE-message
-@subsubsection INVITE-message
-INVITE-messages can be used to invite other members in a room to a different
-room, sharing one potential door and the required key to enter the room. This
-kind of message is typically sent as encrypted PRIVATE-message to selected
-members because it doesn't make much sense to invite all members from one room
-to another considering a rooms key doesn't specify its usage.
-@node TEXT-message
-@subsubsection TEXT-message
-TEXT-messages can be used to send simple text-based messages and should be
-considered as being in readable form without complex decoding. The text has to
-end with a NULL-terminator character and should be in UTF-8 encoding for most
-compatibility.
-@node FILE-message
-@subsubsection FILE-message
-FILE-messages can be used to share files inside of a room. They do not contain
-the actual file being shared but its original hash, filename, URI to download
-the file and a symmetric key to decrypt the downloaded file.
-It is recommended to use the FS subsystem and the FILE-messages in combination.
-@node DELETE-message
-@subsubsection DELETE-message
-DELETE-messages can be used to delete messages selected with its hash. You can
-also select any custom delay relative to the time of sending the DELETE-message.
-Deletion will only be processed on each peer in a room if the sender is
-authorized.
-The only information of a deleted message which being kept will be the chained
-hashes connecting the message graph for potential traversion. For example the
-check for completion of a member session requires this information.
-@node Member sessions
-@subsection Member sessions
-A member session is a triple of the room key, the member ID and the public key
-of the member's ego. Member sessions allow that a member can change their ID or
-their ego once at a time without losing the ability to delete old messages or
-identifying the original sender of a message. On every change of ID or EGO a
-session will be marked as closed. So every session chain will only contain one
-open session with the current ID and public key.
-If a session is marked as closed the MESSENGER service will check from the first
-message opening a session to its last one closing the session for completion. If
-a the service can confirm that there is no message still missing which was sent
-from the closed member session, it will be marked as completed.
-A completed member session is not able to verify any incoming message to ensure
-forward secrecy preventing others from using old stolen egos.
diff --git a/doc/handbook/chapters/installation.texi b/doc/handbook/chapters/installation.texi
deleted file mode 100644
index f93645114..000000000
--- a/doc/handbook/chapters/installation.texi
+++ /dev/null
@@ -1,2497 +0,0 @@
-@node Installing GNUnet
-@chapter Installing GNUnet
-This guide is intended for those who want to install Gnunet from
-source. For instructions on how to install GNUnet as a binary package
-please refer to the official documentation of your operating system or
-package manager.
-For understanding this guide properly it is important to know that
-there are two different ways of running GNUnet:
-@itemize @bullet
-@item the @emph{single-user setup}
-@item the @emph{multi-user setup}
-@end itemize
-The latter variant has a better security model and requires extra
-preparation before running @code{make install} and a different
-configuration. Beginners who want to quickly try out GNUnet can
-use the @emph{single-user setup}.
-@menu
-* Installing dependencies::
-* Getting the Source Code::
-* Create user and groups for the system services::
-* Preparing and Compiling the Source Code::
-* Installation::
-* Minimal configuration::
-* Checking the Installation::
-* The graphical configuration interface::
-* Config Leftovers::
-@end menu
-@c -----------------------------------------------------------------------
-@node Installing dependencies
-@section Installing dependencies
-GNUnet needs few libraries and applications for being able to run and
-another few optional ones for using certain features. Preferably they
-should be installed with a package manager.
-The mandatory libraries and applications are
-@itemize @bullet
-@item autoconf 2.59 or above (when building from git)
-@item automake 1.11.1 or above (when building from git)
-@item recutils 1.0 or above (when building from git)
-@item gettext
-@item glibc (read below, other libcs work)
-@item GnuTLS 3.2.12 or above, recommended to be linked against libunbound
-@item GNU make 4.0 or higher (other make implementations do work)
-@item iptables (on Linux systems)
-@item libtool 2.2 or above
-@item libltdl (part of libtool)
-@item libgcrypt 1.6 or above
-@item libidn2 or libidn
-@item libmicrohttpd 0.9.63 or above
-@item libunistring
-@item libjansson
-@item libgmp
-@item libgnurl or libcurl (libcurl has to be linked to GnuTLS) 7.35.0 or above
-@item Texinfo 5.2 or above (for building the documentation)
-@item Texlive 2012 or above (for building the documentation, and for gnunet-bcd)
-@item makeinfo 4.8 or above
-@item pkgconf (or pkg-config)
-@item zlib
-@end itemize
-Glibc is required for certain NSS features:
-@example
-One mechanism of integrating GNS with legacy applications via NSS is
-not available if this is disabled. But applications that don't use the
-glibc for NS resolution won't work anyway with this, so little is lost
-on *BSD systems.
-GNS via direct use or via the HTTP or DNS proxies is unaffected.
-@end example
-Other libcs should work, the resulting builds just don't include the
-glibc NSS specific code. One example is the build against NetBSD's libc
-as detailed in @uref{https://bugs.gnunet.org/view.php?id=5605}.
-In addition GNUnet needs at least one of these three databases
-(at the minimum sqlite3)
-@itemize @bullet
-@item sqlite + libsqlite 3.8 or above (the default, requires no further configuration)
-@item postgres + libpq
-@item mysql + libmysqlclient
-@end itemize
-These are the dependencies only required for certain features
-@itemize @bullet
-@item miniupnpc (for traversing NAT boxes more reliably)
-@item libnss
-@item libopus (for running the GNUnet conversation telephony application)
-@item libogg (for running the GNUnet conversation telephony application)
-@item gstreamer OR libpulse (for running the GNUnet conversation telephony application)
-@item bluez (for bluetooth support)
-@item libextractor (optional but highly recommended, read below)
-@item libpbc
-(for attribute-based encryption and the identity provider subsystem)
-@item libgabe
-(for attribute-based encryption and the identity provider subsystem)
-@item texi2mdoc (for automatic mdoc generation)
-@item perl5 for some utilities (which are not installed)
-@end itemize
-About libextractor being optional:
-@example
-While libextractor ("LE") is optional, it is recommended to build gnunet
-against it. If you install it later, you won't benefit from libextractor.
-If you are a distributor, we recommend to split LE into basis + plugins
-rather than making LE an option as an afterthought by the user.  LE
-itself is very small, but its dependency chain on first, second, third
-etc level can be big.  There is a small effect on privacy if your LE
-build differs from one which includes all plugins (plugins are build as
-shared objects): if users publish a directory with a mixture of file
-types (for example mpeg, jpeg, png, gif) the configuration of LE could
-leak which plugins are installed for which filetypes are not providing
-more details.  However, this leak is just a minor concern.
-@end example
-These are the test-suite requirements:
-@itemize @bullet
-@item python3.6 or higher
-@item gnunet (installation first)
-@item some core-utils: which(1), bc(1), curl(1), sed(1), awk(1), etc.
-@item a shell (very few Bash scripts, the majority are POSIX sh scripts)
-@end itemize
-These are runtime requirements:
-@itemize @bullet
-@item nss (the certutil binary, for gnunet-gns-proxy-setup-ca)
-@item openssl (openssl binary, for gnunet-gns-proxy-setup-ca)
-@end itemize
-@c -----------------------------------------------------------------------
-@node Getting the Source Code
-@section Getting the Source Code
-You can either download the source code using git (you obviously need
-git installed) or as an archive.
-Using git type
-@example
-git clone https://git.gnunet.org/gnunet.git
-@end example
-The archive can be found at
-@uref{https://ftpmirror.gnu.org/gnu/gnunet/}. Extract it using a graphical
-archive tool or @code{tar}:
-@example
-tar xzvf gnunet-@value{VERSION}.tar.gz
-@end example
-In the next chapter we will assume that the source code is available
-in the home directory at @code{~/gnunet}.
-@c -----------------------------------------------------------------------
-@node Create user and groups for the system services
-@section Create user and groups for the system services
-@cartouche
-For the single-user setup this section can be skipped.
-@end cartouche
-The multi-user setup means that there are @emph{system services}, which are
-run once per machine as a dedicated system user (called @code{gnunet}) and
-@emph{user services} which can be started by every user who wants to use
-GNUnet applications. The user services communicate with the system services
-over unix domain sockets. To gain permissions to read and write those sockets
-the users running GNUnet applications will need to be in the @code{gnunet}
-group. In addition the group @code{gnunetdns} may be needed (see below).
-Create user @code{gnunet} who is member of the group @code{gnunet}
-(automatically created) and specify a home directory where the GNUnet
-services will store persistent data such as information about peers.
-@example
-$ sudo useradd --system --home-dir /var/lib/gnunet --create-home gnunet
-@end example
-Now add your own user to the @code{gnunet} group.
-@example
-$ sudo usermod -aG gnunet alice
-@end example
-Create a group @code{gnunetdns}. This allows using @code{setgid} in a way
-that only the DNS service can run the @code{gnunet-helper-dns} binary. This
-is only needed if @emph{system-wide DNS interception} will be used. For more
-information see @xref{Configuring system-wide DNS interception}.
-@example
-$ sudo groupadd gnunetdns
-@end example
-@c -----------------------------------------------------------------------
-@node Preparing and Compiling the Source Code
-@section Preparing and Compiling the Source Code
-For preparing the source code for compilation a bootstrap script and
-@code{configure} has to be run from the source code directory. When
-running @code{configure} the following options can be specified to
-customize the compilation and installation process:
-@itemize @bullet
-@item @code{--disable-documentation} - don't build the documentation
-@item @code{--enable-logging=[LOGLEVEL]} - choose a loglevel (@code{debug}, @code{info}, @code{warning} or @code{error})
-@item @code{--prefix=[PATH]} - the directory where the GNUnet libraries and binaries will be installed
-@item @code{--with-extractor=[PATH]} - the path to libextractor
-@item @code{--with-libidn=[PATH]} - the path to libidn
-@item @code{--with-libidn2=[PATH]} - the path to libidn2 (takes priority over libidn if both are found)
-@item @code{--with-microhttpd=[PATH]} - the path to libmicrohttpd
-@item @code{--with-sqlite=[PATH]} - the path to libsqlite
-@item @code{--with-zlib=[PATH]} - the path to zlib
-@end itemize
-Note that the list above is not always up to date and you
-should check the output of @code{./configure --help}, read
-the @file{configure.ac} or send an email asking for assistance
-if you are in doubt of any configure options or require fixes
-for your operating system.
-The following example configures the installation prefix
-@code{/usr/local} and disables building the documentation
-@example
-$ cd ~/gnunet
-$ ./bootstrap
-$ configure --prefix=/usr/local --disable-documentation
-@end example
-After running the bootstrap script and @code{configure} successfully
-the source code can be compiled with make. Here @code{-j5} specifies
-that 5 threads should be used.
-@example
-$ make -j5
-@end example
-@c -----------------------------------------------------------------------
-@node Installation
-@section Installation
-The compiled binaries can be installed using @code{make install}. It
-needs to be run as root (or with sudo) because some binaries need the
-@code{suid} bit set. Without that some features (e.g. the VPN service,
-system-wide DNS interception, NAT traversal using ICMP) will not work.
-@example
-$ sudo make install
-@end example
-@menu
-* NSS plugin (Optional)::
-* Installing the GNS Certificate Authority (Optional)::
-@end menu
-@node NSS plugin (Optional)
-@subsection NSS plugin (Optional)
-@cartouche
-The installation of the NSS plugin is only necessary if GNS
-resolution shall be used with legacy applications (that only
-support DNS).
-@end cartouche
-One important library is the GNS plugin for NSS (the name services
-switch) which allows using GNS (the GNU name system) in the normal DNS
-resolution process. Unfortunately NSS expects it in a specific
-location (probably @code{/lib}) which may differ from the installation
-prefix (see @code{--prefix} option in the previous section). This is
-why the plugin has to be installed manually.
-Find the directory where nss plugins are installed on your system, e.g.
-@example
-$ ls -l /lib/libnss_*
-/lib/libnss_mymachines.so.2
-/lib/libnss_resolve.so.2
-/lib/libnss_myhostname.so.2
-/lib/libnss_systemd.so.2
-@end example
-Copy the GNS NSS plugin to that directory:
-@example
-cp ~/gnunet/src/gns/nss/.libs/libnss_gns.so.2 /lib
-@end example
-Now, to activate the plugin, you need to edit your
-@code{/etc/nsswitch.conf} where you should find a line like this:
-@example
-hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4
-@end example
-The exact details may differ a bit, which is fine. Add the text
-@code{"gns [NOTFOUND=return]"} after @code{"files"}.
-@example
-hosts: files gns [NOTFOUND=return] mdns4_minimal [NOTFOUND=return] dns mdns4
-@end example
-@node Installing the GNS Certificate Authority (Optional)
-@subsection Installing the GNS Certificate Authority (Optional)
-@cartouche
-Installing the GNS certificate authority is only necessary if GNS shall
-be used in a browser.
-@end cartouche
-The GNS Certificate authority can provide TLS certificates for GNS names while
-downloading webpages from legacy webservers. This allows browsers to use HTTPS
-in combinations with GNS name resolution.
-To install it execute the GNS CA-setup script. So far Firefox and Chromium are
-supported.
-@example
-$ gnunet-gns-proxy-setup-ca
-@end example
-A local proxy server, that takes care of the name resolution and provides
-certificates on-the-fly needs to be started:
-@example
-$ /usr/lib/gnunet/libexec/gnunet-gns-proxy
-@end example
-Now GNS should work in browsers that are configured to use a SOCKS proxy on
-@code{localhost:7777}.
-@node Minimal configuration
-@section Minimal configuration
-GNUnet needs a configuration file to start (@pxref{Config file format}).
-For the @emph{single-user setup} an empty file is sufficient:
-@example
-$ touch ~/.config/gnunet.conf
-@end example
-For the @emph{multi-user setup} we need an extra config file for the system
-services. The default location is @code{/etc/gnunet.conf}. The minimal
-content of that file which activates the system services roll is:
-@example
-[arm]
-START_SYSTEM_SERVICES = YES
-START_USER_SERVICES = NO
-@end example
-The config file for the user services (@code{~/.config/gnunet.conf}) needs
-the opposite configuration to activate the user services roll:
-@example
-[arm]
-START_SYSTEM_SERVICES = NO
-START_USER_SERVICES = YES
-@end example
-@node Checking the Installation
-@section Checking the Installation
-This section describes a quick, casual way to check if your GNUnet
-installation works. However, if it does not, we do not cover
-steps for recovery --- for this, please study the instructions
-provided in the developer handbook as well as the system-specific
-instruction in the source code repository.
-Please note that the system specific instructions are not provided
-as part of this handbook!
-@menu
-* Starting GNUnet::
-* gnunet-gtk::
-* Statistics::
-* Peer Information::
-@end menu
-@cindex Starting GNUnet
-@cindex GNUnet GTK
-@cindex GTK
-@cindex GTK user interface
-@node Starting GNUnet
-@subsection Starting GNUnet
-The GNUnet services are started and stopped by the ARM service (Automatic
-Restart Manager). For the @emph{single-user setup} a simple
-@example
-$ gnunet-arm -s
-@end example
-starts a default set of services. Later GNUnet applications can request more
-services to start without additional user interaction. GNUnet can be stopped
-again using the @code{-e} option:
-@example
-$ gnunet-arm -e
-@end example
-The list of running services can be displayed using the @code{-I} option.
-It should look similar to this example:
-@example
-$ gnunet-arm -I
-Running services:
-topology (gnunet-daemon-topology)
-nat (gnunet-service-nat)
-vpn (gnunet-service-vpn)
-gns (gnunet-service-gns)
-cadet (gnunet-service-cadet)
-namecache (gnunet-service-namecache)
-hostlist (gnunet-daemon-hostlist)
-revocation (gnunet-service-revocation)
-ats (gnunet-service-ats)
-peerinfo (gnunet-service-peerinfo)
-zonemaster (gnunet-service-zonemaster)
-zonemaster-monitor (gnunet-service-zonemaster-monitor)
-dht (gnunet-service-dht)
-namestore (gnunet-service-namestore)
-set (gnunet-service-set)
-statistics (gnunet-service-statistics)
-nse (gnunet-service-nse)
-fs (gnunet-service-fs)
-peerstore (gnunet-service-peerstore)
-core (gnunet-service-core)
-rest (gnunet-rest-server)
-transport (gnunet-service-transport)
-datastore (gnunet-service-datastore)
-@end example
-For the @emph{multi-user setup} first the system services need to be started
-as the system user, i.e. the user @code{gnunet} needs to execute
-@code{gnunet-arm -s}. This should be done by the system's init system.
-Then the user who wants to start GNUnet applications has to run
-@code{gnunet-arm -s} too. It is recommended to automate this, e.g. using
-the user's crontab.
-@node gnunet-gtk
-@subsection gnunet-gtk
-The @command{gnunet-gtk} package contains several graphical
-user interfaces for the respective GNUnet applications.
-Currently these interfaces cover:
-@itemize @bullet
-@item Statistics
-@item Peer Information
-@item GNU Name System
-@item File Sharing
-@item Conversation
-@item Setup
-@end itemize
-Previously, many of these interfaces were combined into one application
-called @command{gnunet-gtk}, with different tabs for each interface. This
-combined application has been removed in version 0.11.0, but each of the
-interfaces is still available as a standalone application
-(@command{gnunet-statistics-gtk} for statistics, @command{gnunet-fs-gtk}
-for filesharing, etc).
-@node Statistics
-@subsection Statistics
-We assume that you have started gnunet via @code{gnunet-arm} or via your
-system-provided method for starting services.
-First, you should launch GNUnet's graphical statistics interface.
-You can do this from the command-line by typing
-@example
-gnunet-statistics-gtk
-@end example
-If your peer is running correctly, you should see a bunch
-of lines, all of which should be ``significantly'' above zero (at
-least if your peer has been running for more than a few seconds). The
-lines indicate how many other peers your peer is connected to (via
-different mechanisms) and how large the entire overlay network is
-currently estimated to be. The X-axis represents time (in seconds
-since the start of @command{gnunet-statistics-gtk}).
-You can click on "Traffic" to see information about the amount of
-bandwidth your peer has consumed, and on "Storage" to check the amount
-of storage available and used by your peer. Note that "Traffic" is
-plotted cumulatively, so you should see a strict upwards trend in the
-traffic.
-The term ``peer'' is a common word used in
-federated and distributed networks to describe a participating device
-which is connected to the network. Thus, your Personal Computer or
-whatever it is you are looking at the Gtk+ interface describes a
-``Peer'' or a ``Node''.
-@node Peer Information
-@subsection Peer Information
-First, you should launch the peer information graphical user interface.
-You can do this from the command-line by typing
-@example
-$ gnunet-peerinfo-gtk
-@end example
-Once you have done this, you will see a list of known peers (by the
-first four characters of their public key), their friend status (all
-should be marked as not-friends initially), their connectivity (green
-is connected, red is disconnected), assigned bandwidth, country of
-origin (if determined) and address information. If hardly any peers
-are listed and/or if there are very few peers with a green light for
-connectivity, there is likely a problem with your network
-configuration.
-@c NOTE: Inserted from Installation Handbook in original ``order'':
-@c FIXME: Move this to User Handbook.
-@node The graphical configuration interface
-@section The graphical configuration interface
-If you also would like to use @command{gnunet-gtk} and
-@command{gnunet-setup} (highly recommended for beginners), do:
-@menu
-* Configuring your peer::
-* Configuring the Friend-to-Friend (F2F) mode::
-* Configuring the hostlist to bootstrap::
-* Configuration of the HOSTLIST proxy settings::
-* Configuring your peer to provide a hostlist ::
-* Configuring the datastore::
-* Configuring the MySQL database::
-* Reasons for using MySQL::
-* Reasons for not using MySQL::
-* Setup Instructions::
-* Testing::
-* Performance Tuning::
-* Setup for running Testcases::
-* Configuring the Postgres database::
-* Reasons to use Postgres::
-* Reasons not to use Postgres::
-* Manual setup instructions::
-* Testing the setup manually::
-* Configuring the datacache::
-* Configuring the file-sharing service::
-* Configuring logging::
-* Configuring the transport service and plugins::
-* Configuring the WLAN transport plugin::
-* Configuring HTTP(S) reverse proxy functionality using Apache or nginx::
-* Blacklisting peers::
-* Configuration of the HTTP and HTTPS transport plugins::
-* Configuring the GNU Name System::
-* Configuring the GNUnet VPN::
-* Bandwidth Configuration::
-* Configuring NAT::
-* Peer configuration for distributors (e.g. Operating Systems)::
-@end menu
-@node Configuring your peer
-@subsection Configuring your peer
-This chapter will describe the various configuration options in GNUnet.
-The easiest way to configure your peer is to use the
-@command{gnunet-setup} tool.
-@command{gnunet-setup} is part of the @command{gnunet-gtk}
-package. You might have to install it separately.
-Many of the specific sections from this chapter actually are linked from
-within @command{gnunet-setup} to help you while using the setup tool.
-While you can also configure your peer by editing the configuration
-file by hand, this is not recommended for anyone except for developers
-as it requires a more in-depth understanding of the configuration files
-and internal dependencies of GNUnet.
-@node Configuring the Friend-to-Friend (F2F) mode
-@subsection Configuring the Friend-to-Friend (F2F) mode
-GNUnet knows three basic modes of operation:
-@itemize @bullet
-@item In standard "peer-to-peer" mode,
-your peer will connect to any peer.
-@item In the pure "friend-to-friend"
-mode, your peer will ONLY connect to peers from a list of friends
-specified in the configuration.
-@item Finally, in mixed mode,
-GNUnet will only connect to arbitrary peers if it
-has at least a specified number of connections to friends.
-@end itemize
-When configuring any of the F2F ("friend-to-friend") modes,
-you first need to create a file with the peer identities
-of your friends. Ask your friends to run
-@example
-$ gnunet-peerinfo -sq
-@end example
-@noindent
-The resulting output of this command needs to be added to your
-@file{friends} file, which is simply a plain text file with one line
-per friend with the output from the above command.
-You then specify the location of your @file{friends} file in the
-@code{FRIENDS} option of the "topology" section.
-Once you have created the @file{friends} file, you can tell GNUnet to only
-connect to your friends by setting the @code{FRIENDS-ONLY} option
-(again in the "topology" section) to YES.
-If you want to run in mixed-mode, set "FRIENDS-ONLY" to NO and configure a
-minimum number of friends to have (before connecting to arbitrary peers)
-under the "MINIMUM-FRIENDS" option.
-If you want to operate in normal P2P-only mode, simply set
-@code{MINIMUM-FRIENDS} to zero and @code{FRIENDS_ONLY} to NO.
-This is the default.
-@node Configuring the hostlist to bootstrap
-@subsection Configuring the hostlist to bootstrap
-After installing the software you need to get connected to the GNUnet
-network. The configuration file included in your download is already
-configured to connect you to the GNUnet network.
-In this section the relevant configuration settings are explained.
-To get an initial connection to the GNUnet network and to get to know
-peers already connected to the network you can use the so called
-"bootstrap servers".
-These servers can give you a list of peers connected to the network.
-To use these bootstrap servers you have to configure the hostlist daemon
-to activate bootstrapping.
-To activate bootstrapping, edit the @code{[hostlist]}-section in your
-configuration file. You have to set the argument @command{-b} in the
-options line:
-@example
-[hostlist]
-OPTIONS = -b
-@end example
-Additionally you have to specify which server you want to use.
-The default bootstrapping server is
-"@uref{http://v10.gnunet.org/hostlist, http://v10.gnunet.org/hostlist}".
-[^] To set the server you have to edit the line "SERVERS" in the hostlist
-section. To use the default server you should set the lines to
-@example
-SERVERS = http://v10.gnunet.org/hostlist [^]
-@end example
-@noindent
-To use bootstrapping your configuration file should include these lines:
-@example
-[hostlist]
-OPTIONS = -b
-SERVERS = http://v10.gnunet.org/hostlist [^]
-@end example
-@noindent
-Besides using bootstrap servers you can configure your GNUnet peer to
-receive hostlist advertisements.
-Peers offering hostlists to other peers can send advertisement messages
-to peers that connect to them. If you configure your peer to receive these
-messages, your peer can download these lists and connect to the peers
-included. These lists are persistent, which means that they are saved to
-your hard disk regularly and are loaded during startup.
-To activate hostlist learning you have to add the @command{-e}
-switch to the @code{OPTIONS} line in the hostlist section:
-@example
-[hostlist]
-OPTIONS = -b -e
-@end example
-@noindent
-Furthermore you can specify in which file the lists are saved.
-To save the lists in the file @file{hostlists.file} just add the line:
-@example
-HOSTLISTFILE = hostlists.file
-@end example
-@noindent
-Best practice is to activate both bootstrapping and hostlist learning.
-So your configuration file should include these lines:
-@example
-[hostlist]
-OPTIONS = -b -e
-HTTPPORT = 8080
-SERVERS = http://v10.gnunet.org/hostlist [^]
-HOSTLISTFILE = $SERVICEHOME/hostlists.file
-@end example
-@node Configuration of the HOSTLIST proxy settings
-@subsection Configuration of the HOSTLIST proxy settings
-The hostlist client can be configured to use a proxy to connect to the
-hostlist server.
-This functionality can be configured in the configuration file directly
-or using the @command{gnunet-setup} tool.
-The hostlist client supports the following proxy types at the moment:
-@itemize @bullet
-@item HTTP and HTTP 1.0 only proxy
-@item SOCKS 4/4a/5/5 with hostname
-@end itemize
-In addition authentication at the proxy with username and password can be
-configured.
-To configure proxy support for the hostlist client in the
-@command{gnunet-setup} tool, select the "hostlist" tab and select
-the appropriate proxy type.
-The hostname or IP address (including port if required) has to be entered
-in the "Proxy hostname" textbox. If required, enter username and password
-in the "Proxy username" and "Proxy password" boxes.
-Be aware that this information will be stored in the configuration in
-plain text (TODO: Add explanation and generalize the part in Chapter 3.6
-about the encrypted home).
-To provide these options directly in the configuration, you can
-enter the following settings in the @code{[hostlist]} section of
-the configuration:
-@example
-# Type of proxy server,
-# Valid values: HTTP, HTTP_1_0, SOCKS4, SOCKS5, SOCKS4A, SOCKS5_HOSTNAME
-# Default: HTTP
-# PROXY_TYPE = HTTP
-# Hostname or IP of proxy server
-# PROXY =
-# User name for proxy server
-# PROXY_USERNAME =
-# User password for proxy server
-# PROXY_PASSWORD =
-@end example
-@node Configuring your peer to provide a hostlist
-@subsection Configuring your peer to provide a hostlist
-If you operate a peer permanently connected to GNUnet you can configure
-your peer to act as a hostlist server, providing other peers the list of
-peers known to him.
-Your server can act as a bootstrap server and peers needing to obtain a
-list of peers can contact it to download this list.
-To download this hostlist the peer uses HTTP.
-For this reason you have to build your peer with libgnurl (or libcurl)
-and microhttpd support.
-To configure your peer to act as a bootstrap server you have to add the
-@command{-p} option to @code{OPTIONS} in the @code{[hostlist]} section
-of your configuration file.
-Besides that you have to specify a port number for the http server.
-In conclusion you have to add the following lines:
-@example
-[hostlist]
-HTTPPORT = 12980
-OPTIONS = -p
-@end example
-@noindent
-If your peer acts as a bootstrap server other peers should know about
-that. You can advertise the hostlist your are providing to other peers.
-Peers connecting to your peer will get a message containing an
-advertisement for your hostlist and the URL where it can be downloaded.
-If this peer is in learning mode, it will test the hostlist and, in the
-case it can obtain the list successfully, it will save it for
-bootstrapping.
-To activate hostlist advertisement on your peer, you have to set the
-following lines in your configuration file:
-@example
-[hostlist]
-EXTERNAL_DNS_NAME = example.org
-HTTPPORT = 12981
-OPTIONS = -p -a
-@end example
-@noindent
-With this configuration your peer will a act as a bootstrap server and
-advertise this hostlist to other peers connecting to it.
-The URL used to download the list will be
-@code{@uref{http://example.org:12981/, http://example.org:12981/}}.
-Please notice:
-@itemize @bullet
-@item The hostlist is @b{not} human readable, so you should not try to
-download it using your webbrowser. Just point your GNUnet peer to the
-address!
-@item Advertising without providing a hostlist does not make sense and
-will not work.
-@end itemize
-@node Configuring the datastore
-@subsection Configuring the datastore
-The datastore is what GNUnet uses for long-term storage of file-sharing
-data. Note that long-term does not mean 'forever' since content does have
-an expiration date, and of course storage space is finite (and hence
-sometimes content may have to be discarded).
-Use the @code{QUOTA} option to specify how many bytes of storage space
-you are willing to dedicate to GNUnet.
-In addition to specifying the maximum space GNUnet is allowed to use for
-the datastore, you need to specify which database GNUnet should use to do
-so. Currently, you have the choice between sqLite, MySQL and Postgres.
-@node Configuring the MySQL database
-@subsection Configuring the MySQL database
-This section describes how to setup the MySQL database for GNUnet.
-Note that the mysql plugin does NOT work with mysql before 4.1 since we
-need prepared statements.
-We are generally testing the code against MySQL 5.1 at this point.
-@node Reasons for using MySQL
-@subsection Reasons for using MySQL
-@itemize @bullet
-@item On up-to-date hardware where
-mysql can be used comfortably, this module
-will have better performance than the other database choices (according
-to our tests).
-@item Its often possible to recover the mysql database from internal
-inconsistencies. Some of the other databases do not support repair.
-@end itemize
-@node Reasons for not using MySQL
-@subsection Reasons for not using MySQL
-@itemize @bullet
-@item Memory usage (likely not an issue if you have more than 1 GB)
-@item Complex manual setup
-@end itemize
-@node Setup Instructions
-@subsection Setup Instructions
-@itemize @bullet
-@item In @file{gnunet.conf} set in section @code{DATASTORE} the value for
-@code{DATABASE} to @code{mysql}.
-@item Access mysql as root:
-@example
-$ mysql -u root -p
-@end example
-@noindent
-and issue the following commands, replacing $USER with the username
-that will be running @command{gnunet-arm} (so typically "gnunet"):
-@example
-CREATE DATABASE gnunet;
-GRANT select,insert,update,delete,create,alter,drop,create \
-temporary tables ON gnunet.* TO $USER@@localhost;
-SET PASSWORD FOR $USER@@localhost=PASSWORD('$the_password_you_like');
-FLUSH PRIVILEGES;
-@end example
-@item
-In the $HOME directory of $USER, create a @file{.my.cnf} file with the
-following lines
-@example
-[client]
-user=$USER
-password=$the_password_you_like
-@end example
-@end itemize
-That's it. Note that @file{.my.cnf} file is a slight security risk unless
-its on a safe partition. The @file{$HOME/.my.cnf} can of course be
-a symbolic link.
-Luckily $USER has only privileges to mess up GNUnet's tables,
-which should be pretty harmless.
-@node Testing
-@subsection Testing
-You should briefly try if the database connection works. First, login
-as $USER. Then use:
-@example
-$ mysql -u $USER
-mysql> use gnunet;
-@end example
-@noindent
-If you get the message
-@example
-Database changed
-@end example
-@noindent
-it probably works.
-If you get
-@example
-ERROR 2002: Can't connect to local MySQL server
-through socket '/tmp/mysql.sock' (2)
-@end example
-@noindent
-it may be resolvable by
-@example
-ln -s /var/run/mysqld/mysqld.sock /tmp/mysql.sock
-@end example
-@noindent
-so there may be some additional trouble depending on your mysql setup.
-@node Performance Tuning
-@subsection Performance Tuning
-For GNUnet, you probably want to set the option
-@example
-innodb_flush_log_at_trx_commit = 0
-@end example
-@noindent
-for a rather dramatic boost in MySQL performance. However, this reduces
-the "safety" of your database as with this options you may loose
-transactions during a power outage.
-While this is totally harmless for GNUnet, the option applies to all
-applications using MySQL. So you should set it if (and only if) GNUnet is
-the only application on your system using MySQL.
-@node Setup for running Testcases
-@subsection Setup for running Testcases
-If you want to run the testcases, you must create a second database
-"gnunetcheck" with the same username and password. This database will
-then be used for testing (@command{make check}).
-@node Configuring the Postgres database
-@subsection Configuring the Postgres database
-This text describes how to setup the Postgres database for GNUnet.
-This Postgres plugin was developed for Postgres 8.3 but might work for
-earlier versions as well.
-@node Reasons to use Postgres
-@subsection Reasons to use Postgres
-@itemize @bullet
-@item Easier to setup than MySQL
-@item Real database
-@end itemize
-@node Reasons not to use Postgres
-@subsection Reasons not to use Postgres
-@itemize @bullet
-@item Quite slow
-@item Still some manual setup required
-@end itemize
-@node Manual setup instructions
-@subsection Manual setup instructions
-@itemize @bullet
-@item In @file{gnunet.conf} set in section @code{DATASTORE} the value for
-@code{DATABASE} to @code{postgres}.
-@item Access Postgres to create a user:
-@table @asis
-@item with Postgres 8.x, use:
-@example
-# su - postgres
-$ createuser
-@end example
-@noindent
-and enter the name of the user running GNUnet for the role interactively.
-Then, when prompted, do not set it to superuser, allow the creation of
-databases, and do not allow the creation of new roles.
-@item with Postgres 9.x, use:
-@example
-# su - postgres
-$ createuser -d $GNUNET_USER
-@end example
-@noindent
-where $GNUNET_USER is the name of the user running GNUnet.
-@end table
-@item
-As that user (so typically as user "gnunet"), create a database (or two):
-@example
-$ createdb gnunet
-# this way you can run "make check"
-$ createdb gnunetcheck
-@end example
-@end itemize
-Now you should be able to start @code{gnunet-arm}.
-@node Testing the setup manually
-@subsection Testing the setup manually
-You may want to try if the database connection works. First, again login
-as the user who will run @command{gnunet-arm}. Then use:
-@example
-$ psql gnunet # or gnunetcheck
-gnunet=> \dt
-@end example
-@noindent
-If, after you have started @command{gnunet-arm} at least once, you get
-a @code{gn090} table here, it probably works.
-@node Configuring the datacache
-@subsection Configuring the datacache
-The datacache is what GNUnet uses for storing temporary data. This data is
-expected to be wiped completely each time GNUnet is restarted (or the
-system is rebooted).
-You need to specify how many bytes GNUnet is allowed to use for the
-datacache using the @code{QUOTA} option in the section @code{[dhtcache]}.
-Furthermore, you need to specify which database backend should be used to
-store the data. Currently, you have the choice between
-sqLite, MySQL and Postgres.
-@node Configuring the file-sharing service
-@subsection Configuring the file-sharing service
-In order to use GNUnet for file-sharing, you first need to make sure
-that the file-sharing service is loaded.
-This is done by setting the @code{START_ON_DEMAND} option in
-section @code{[fs]} to "YES". Alternatively, you can run
-@example
-$ gnunet-arm -i fs
-@end example
-@noindent
-to start the file-sharing service by hand.
-Except for configuring the database and the datacache the only important
-option for file-sharing is content migration.
-Content migration allows your peer to cache content from other peers as
-well as send out content stored on your system without explicit requests.
-This content replication has positive and negative impacts on both system
-performance and privacy.
-FIXME: discuss the trade-offs. Here is some older text about it...
-Setting this option to YES allows gnunetd to migrate data to the local
-machine. Setting this option to YES is highly recommended for efficiency.
-Its also the default. If you set this value to YES, GNUnet will store
-content on your machine that you cannot decrypt.
-While this may protect you from liability if the judge is sane, it may
-not (IANAL). If you put illegal content on your machine yourself, setting
-this option to YES will probably increase your chances to get away with it
-since you can plausibly deny that you inserted the content.
-Note that in either case, your anonymity would have to be broken first
-(which may be possible depending on the size of the GNUnet network and the
-strength of the adversary).
-@node Configuring logging
-@subsection Configuring logging
-Since version 0.9.0, logging in GNUnet is controlled via the
-@code{-L} and @code{-l} options.
-Using @code{-L}, a log level can be specified. With log level
-@code{ERROR} only serious errors are logged.
-The default log level is @code{WARNING} which causes anything of
-concern to be logged.
-Log level @code{INFO} can be used to log anything that might be
-interesting information whereas
-@code{DEBUG} can be used by developers to log debugging messages
-(but you need to run @code{./configure} with
-@code{--enable-logging=verbose} to get them compiled).
-The @code{-l} option is used to specify the log file.
-Since most GNUnet services are managed by @code{gnunet-arm}, using the
-@code{-l} or @code{-L} options directly is not possible.
-Instead, they can be specified using the @code{OPTIONS} configuration
-value in the respective section for the respective service.
-In order to enable logging globally without editing the @code{OPTIONS}
-values for each service, @command{gnunet-arm} supports a
-@code{GLOBAL_POSTFIX} option.
-The value specified here is given as an extra option to all services for
-which the configuration does contain a service-specific @code{OPTIONS}
-field.
-@code{GLOBAL_POSTFIX} can contain the special sequence "@{@}" which
-is replaced by the name of the service that is being started.
-Furthermore, @code{GLOBAL_POSTFIX} is special in that sequences
-starting with "$" anywhere in the string are expanded (according
-to options in @code{PATHS}); this expansion otherwise is
-only happening for filenames and then the "$" must be the
-first character in the option. Both of these restrictions do
-not apply to @code{GLOBAL_POSTFIX}.
-Note that specifying @code{%} anywhere in the @code{GLOBAL_POSTFIX}
-disables both of these features.
-In summary, in order to get all services to log at level
-@code{INFO} to log-files called @code{SERVICENAME-logs}, the
-following global prefix should be used:
-@example
-GLOBAL_POSTFIX = -l $SERVICEHOME/@{@}-logs -L INFO
-@end example
-@node Configuring the transport service and plugins
-@subsection Configuring the transport service and plugins
-The transport service in GNUnet is responsible to maintain basic
-connectivity to other peers.
-Besides initiating and keeping connections alive it is also responsible
-for address validation.
-The GNUnet transport supports more than one transport protocol.
-These protocols are configured together with the transport service.
-The configuration section for the transport service itself is quite
-similar to all the other services
-@example
-START_ON_DEMAND = YES
-@@UNIXONLY@@ PORT = 2091
-HOSTNAME = localhost
-HOME = $SERVICEHOME
-CONFIG = $DEFAULTCONFIG
-BINARY = gnunet-service-transport
-#PREFIX = valgrind
-NEIGHBOUR_LIMIT = 50
-ACCEPT_FROM = 127.0.0.1;
-ACCEPT_FROM6 = ::1;
-PLUGINS = tcp udp
-UNIXPATH = /tmp/gnunet-service-transport.sock
-@end example
-Different are the settings for the plugins to load @code{PLUGINS}.
-The first setting specifies which transport plugins to load.
-@itemize @bullet
-@item transport-unix
-A plugin for local only communication with UNIX domain sockets. Used for
-testing and available on unix systems only. Just set the port
-@example
-[transport-unix]
-PORT = 22086
-TESTING_IGNORE_KEYS = ACCEPT_FROM;
-@end example
-@item transport-tcp
-A plugin for communication with TCP. Set port to 0 for client mode with
-outbound only connections
-@example
-[transport-tcp]
-# Use 0 to ONLY advertise as a peer behind NAT (no port binding)
-PORT = 2086
-ADVERTISED_PORT = 2086
-TESTING_IGNORE_KEYS = ACCEPT_FROM;
-# Maximum number of open TCP connections allowed
-MAX_CONNECTIONS = 128
-@end example
-@item transport-udp
-A plugin for communication with UDP. Supports peer discovery using
-broadcasts.
-@example
-[transport-udp]
-PORT = 2086
-BROADCAST = YES
-BROADCAST_INTERVAL = 30 s
-MAX_BPS = 1000000
-TESTING_IGNORE_KEYS = ACCEPT_FROM;
-@end example
-@item transport-http
-HTTP and HTTPS support is split in two part: a client plugin initiating
-outbound connections and a server part accepting connections from the
-client. The client plugin just takes the maximum number of connections as
-an argument.
-@example
-[transport-http_client]
-MAX_CONNECTIONS = 128
-TESTING_IGNORE_KEYS = ACCEPT_FROM;
-@end example
-@example
-[transport-https_client]
-MAX_CONNECTIONS = 128
-TESTING_IGNORE_KEYS = ACCEPT_FROM;
-@end example
-@noindent
-The server has a port configured and the maximum number of connections.
-The HTTPS part has two files with the certificate key and the certificate
-file.
-The server plugin supports reverse proxies, so a external hostname can be
-set using the @code{EXTERNAL_HOSTNAME} setting.
-The webserver under this address should forward the request to the peer
-and the configure port.
-@example
-[transport-http_server]
-EXTERNAL_HOSTNAME = fulcrum.net.in.tum.de/gnunet
-PORT = 1080
-MAX_CONNECTIONS = 128
-TESTING_IGNORE_KEYS = ACCEPT_FROM;
-@end example
-@example
-[transport-https_server]
-PORT = 4433
-CRYPTO_INIT = NORMAL
-KEY_FILE = https.key
-CERT_FILE = https.cert
-MAX_CONNECTIONS = 128
-TESTING_IGNORE_KEYS = ACCEPT_FROM;
-@end example
-@item transport-wlan
-The next section describes how to setup the WLAN plugin,
-so here only the settings. Just specify the interface to use:
-@example
-[transport-wlan]
-# Name of the interface in monitor mode (typically monX)
-INTERFACE = mon0
-# Real hardware, no testing
-TESTMODE = 0
-TESTING_IGNORE_KEYS = ACCEPT_FROM;
-@end example
-@end itemize
-@node Configuring the WLAN transport plugin
-@subsection Configuring the WLAN transport plugin
-The wlan transport plugin enables GNUnet to send and to receive data on a
-wlan interface.
-It has not to be connected to a wlan network as long as sender and
-receiver are on the same channel. This enables you to get connection to
-GNUnet where no internet access is possible, for example during
-catastrophes or when censorship cuts you off from the internet.
-@menu
-* Requirements for the WLAN plugin::
-* Configuration::
-* Before starting GNUnet::
-* Limitations and known bugs::
-@end menu
-@node Requirements for the WLAN plugin
-@subsubsection Requirements for the WLAN plugin
-@itemize @bullet
-@item wlan network card with monitor support and packet injection
-(see @uref{http://www.aircrack-ng.org/, aircrack-ng.org})
-@item Linux kernel with mac80211 stack, introduced in 2.6.22, tested with
-2.6.35 and 2.6.38
-@item Wlantools to create the a monitor interface, tested with airmon-ng
-of the aircrack-ng package
-@end itemize
-@node Configuration
-@subsubsection Configuration
-There are the following options for the wlan plugin (they should be like
-this in your default config file, you only need to adjust them if the
-values are incorrect for your system)
-@example
-# section for the wlan transport plugin
-[transport-wlan]
-# interface to use, more information in the
-# "Before starting GNUnet" section of the handbook.
-INTERFACE = mon0
-# testmode for developers:
-# 0 use wlan interface,
-#1 or 2 use loopback driver for tests 1 = server, 2 = client
-TESTMODE = 0
-@end example
-@node Before starting GNUnet
-@subsubsection Before starting GNUnet
-Before starting GNUnet, you have to make sure that your wlan interface is
-in monitor mode.
-One way to put the wlan interface into monitor mode (if your interface
-name is wlan0) is by executing:
-@example
-sudo airmon-ng start wlan0
-@end example
-@noindent
-Here is an example what the result should look like:
-@example
-Interface Chipset Driver
-wlan0 Intel 4965 a/b/g/n iwl4965 - [phy0]
-(monitor mode enabled on mon0)
-@end example
-@noindent
-The monitor interface is mon0 is the one that you have to put into the
-configuration file.
-@node Limitations and known bugs
-@subsubsection Limitations and known bugs
-Wlan speed is at the maximum of 1 Mbit/s because support for choosing the
-wlan speed with packet injection was removed in newer kernels.
-Please pester the kernel developers about fixing this.
-The interface channel depends on the wlan network that the card is
-connected to. If no connection has been made since the start of the
-computer, it is usually the first channel of the card.
-Peers will only find each other and communicate if they are on the same
-channel. Channels must be set manually, e.g. by using:
-@example
-iwconfig wlan0 channel 1
-@end example
-@node Configuring HTTP(S) reverse proxy functionality using Apache or nginx
-@subsection Configuring HTTP(S) reverse proxy functionality using Apache or nginx
-The HTTP plugin supports data transfer using reverse proxies. A reverse
-proxy forwards the HTTP request he receives with a certain URL to another
-webserver, here a GNUnet peer.
-So if you have a running Apache or nginx webserver you can configure it to
-be a GNUnet reverse proxy. Especially if you have a well-known website
-this improves censorship resistance since it looks as normal surfing
-behaviour.
-To do so, you have to do two things:
-@itemize @bullet
-@item Configure your webserver to forward the GNUnet HTTP traffic
-@item Configure your GNUnet peer to announce the respective address
-@end itemize
-As an example we want to use GNUnet peer running:
-@itemize @bullet
-@item HTTP server plugin on @code{gnunet.foo.org:1080}
-@item HTTPS server plugin on @code{gnunet.foo.org:4433}
-@item A apache or nginx webserver on
-@uref{http://www.foo.org/, http://www.foo.org:80/}
-@item A apache or nginx webserver on https://www.foo.org:443/
-@end itemize
-And we want the webserver to accept GNUnet traffic under
-@code{http://www.foo.org/bar/}. The required steps are described here:
-@menu
-* Reverse Proxy - Configure your Apache2 HTTP webserver::
-* Reverse Proxy - Configure your Apache2 HTTPS webserver::
-* Reverse Proxy - Configure your nginx HTTPS webserver::
-* Reverse Proxy - Configure your nginx HTTP webserver::
-* Reverse Proxy - Configure your GNUnet peer::
-@end menu
-@node Reverse Proxy - Configure your Apache2 HTTP webserver
-@subsubsection Reverse Proxy - Configure your Apache2 HTTP webserver
-First of all you need mod_proxy installed.
-Edit your webserver configuration. Edit
-@code{/etc/apache2/apache2.conf} or the site-specific configuration file.
-In the respective @code{server config},@code{virtual host} or
-@code{directory} section add the following lines:
-@example
-ProxyTimeout 300
-ProxyRequests Off
-<Location /bar/ >
-ProxyPass http://gnunet.foo.org:1080/
-ProxyPassReverse http://gnunet.foo.org:1080/
-</Location>
-@end example
-@node Reverse Proxy - Configure your Apache2 HTTPS webserver
-@subsubsection Reverse Proxy - Configure your Apache2 HTTPS webserver
-We assume that you already have an HTTPS server running, if not please
-check how to configure a HTTPS host. An uncomplicated to use example
-is the example configuration file for Apache2/HTTPD provided in
-@file{apache2/sites-available/default-ssl}.
-In the respective HTTPS @code{server config},@code{virtual host} or
-@code{directory} section add the following lines:
-@example
-SSLProxyEngine On
-ProxyTimeout 300
-ProxyRequests Off
-<Location /bar/ >
-ProxyPass https://gnunet.foo.org:4433/
-ProxyPassReverse https://gnunet.foo.org:4433/
-</Location>
-@end example
-@noindent
-More information about the apache mod_proxy configuration can be found
-in the
-@uref{http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#proxypass, Apache documentation}.
-@node Reverse Proxy - Configure your nginx HTTPS webserver
-@subsubsection Reverse Proxy - Configure your nginx HTTPS webserver
-Since nginx does not support chunked encoding, you first of all have to
-install the @code{chunkin}
-@uref{http://wiki.nginx.org/HttpChunkinModule, module}.
-To enable chunkin add:
-@example
-chunkin on;
-error_page 411 = @@my_411_error;
-location @@my_411_error @{
-chunkin_resume;
-@}
-@end example
-@noindent
-Edit your webserver configuration. Edit @file{/etc/nginx/nginx.conf} or
-the site-specific configuration file.
-In the @code{server} section add:
-@example
-location /bar/ @{
-proxy_pass http://gnunet.foo.org:1080/;
-proxy_buffering off;
-proxy_connect_timeout 5; # more than http_server
-proxy_read_timeout 350; # 60 default, 300s is GNUnet's idle timeout
-proxy_http_version 1.1; # 1.0 default
-proxy_next_upstream error timeout invalid_header http_500 http_503 http_502 http_504;
-@}
-@end example
-@node Reverse Proxy - Configure your nginx HTTP webserver
-@subsubsection Reverse Proxy - Configure your nginx HTTP webserver
-Edit your webserver configuration. Edit @file{/etc/nginx/nginx.conf} or
-the site-specific configuration file.
-In the @code{server} section add:
-@example
-ssl_session_timeout 6m;
-location /bar/
-@{
-proxy_pass https://gnunet.foo.org:4433/;
-proxy_buffering off;
-proxy_connect_timeout 5; # more than http_server
-proxy_read_timeout 350; # 60 default, 300s is GNUnet's idle timeout
-proxy_http_version 1.1; # 1.0 default
-proxy_next_upstream error timeout invalid_header http_500 http_503 http_502 http_504;
-@}
-@end example
-@node Reverse Proxy - Configure your GNUnet peer
-@subsubsection Reverse Proxy - Configure your GNUnet peer
-To have your GNUnet peer announce the address, you have to specify the
-@code{EXTERNAL_HOSTNAME} option in the @code{[transport-http_server]}
-section:
-@example
-[transport-http_server]
-EXTERNAL_HOSTNAME = http://www.foo.org/bar/
-@end example
-@noindent
-and/or @code{[transport-https_server]} section:
-@example
-[transport-https_server]
-EXTERNAL_HOSTNAME = https://www.foo.org/bar/
-@end example
-@noindent
-Now restart your webserver and your peer...
-@node Blacklisting peers
-@subsection Blacklisting peers
-Transport service supports to deny connecting to a specific peer of to a
-specific peer with a specific transport plugin using the blacklisting
-component of transport service. With@ blacklisting it is possible to deny
-connections to specific peers of@ to use a specific plugin to a specific
-peer. Peers can be blacklisted using@ the configuration or a blacklist
-client can be asked.
-To blacklist peers using the configuration you have to add a section to
-your configuration containing the peer id of the peer to blacklist and
-the plugin@ if required.
-Examples:
-To blacklist connections to P565... on peer AG2P... using tcp add:
-@c FIXME: This is too long and produces errors in the pdf.
-@example
-[transport-blacklist AG2PHES1BARB9IJCPAMJTFPVJ5V3A72S3F2A8SBUB8DAQ2V0O3V8G6G2JU56FHGFOHMQVKBSQFV98TCGTC3RJ1NINP82G0RC00N1520]
-P565723JO1C2HSN6J29TAQ22MN6CI8HTMUU55T0FUQG4CMDGGEQ8UCNBKUMB94GC8R9G4FB2SF9LDOBAJ6AMINBP4JHHDD6L7VD801G = tcp
-@end example
-To blacklist connections to P565... on peer AG2P... using all plugins add:
-@example
-[transport-blacklist-AG2PHES1BARB9IJCPAMJTFPVJ5V3A72S3F2A8SBUB8DAQ2V0O3V8G6G2JU56FHGFOHMQVKBSQFV98TCGTC3RJ1NINP82G0RC00N1520]
-P565723JO1C2HSN6J29TAQ22MN6CI8HTMUU55T0FUQG4CMDGGEQ8UCNBKUMB94GC8R9G4FB2SF9LDOBAJ6AMINBP4JHHDD6L7VD801G =
-@end example
-You can also add a blacklist client using the blacklist API. On a
-blacklist check, blacklisting first checks internally if the peer is
-blacklisted and if not, it asks the blacklisting clients. Clients are
-asked if it is OK to connect to a peer ID, the plugin is omitted.
-On blacklist check for (peer, plugin)
-@itemize @bullet
-@item Do we have a local blacklist entry for this peer and this plugin?
-@item YES: disallow connection
-@item Do we have a local blacklist entry for this peer and all plugins?
-@item YES: disallow connection
-@item Does one of the clients disallow?
-@item YES: disallow connection
-@end itemize
-@node Configuration of the HTTP and HTTPS transport plugins
-@subsection Configuration of the HTTP and HTTPS transport plugins
-The client parts of the http and https transport plugins can be configured
-to use a proxy to connect to the hostlist server. This functionality can
-be configured in the configuration file directly or using the
-gnunet-setup tool.
-Both the HTTP and HTTPS clients support the following proxy types at
-the moment:
-@itemize @bullet
-@item HTTP 1.1 proxy
-@item SOCKS 4/4a/5/5 with hostname
-@end itemize
-In addition authentication at the proxy with username and password can be
-configured.
-To configure proxy support for the clients in the gnunet-setup tool,
-select the "transport" tab and activate the respective plugin. Now you
-can select the appropriate proxy type. The hostname or IP address
-(including port if required) has to be entered in the "Proxy hostname"
-textbox. If required, enter username and password in the "Proxy username"
-and "Proxy password" boxes. Be aware that these information will be stored
-in the configuration in plain text.
-To configure these options directly in the configuration, you can
-configure the following settings in the @code{[transport-http_client]}
-and @code{[transport-https_client]} section of the configuration:
-@example
-# Type of proxy server,
-# Valid values: HTTP, SOCKS4, SOCKS5, SOCKS4A, SOCKS5_HOSTNAME
-# Default: HTTP
-# PROXY_TYPE = HTTP
-# Hostname or IP of proxy server
-# PROXY =
-# User name for proxy server
-# PROXY_USERNAME =
-# User password for proxy server
-# PROXY_PASSWORD =
-@end example
-@node Configuring the GNU Name System
-@subsection Configuring the GNU Name System
-@menu
-* Configuring system-wide DNS interception::
-* Configuring the GNS nsswitch plugin::
-@c * Configuring GNS on W32::
-* GNS Proxy Setup::
-* Setup of the GNS CA::
-* Testing the GNS setup::
-* Migrating existing DNS zones into GNS::
-@end menu
-@node Configuring system-wide DNS interception
-@subsubsection Configuring system-wide DNS interception
-Before you install GNUnet, make sure you have a user and group 'gnunet'
-as well as an empty group 'gnunetdns'.
-When using GNUnet with system-wide DNS interception, it is absolutely
-necessary for all GNUnet service processes to be started by
-@code{gnunet-service-arm} as user and group 'gnunet'. You also need to be
-sure to run @code{make install} as root (or use the @code{sudo} option to
-configure) to grant GNUnet sufficient privileges.
-With this setup, all that is required for enabling system-wide DNS
-interception is for some GNUnet component (VPN or GNS) to request it.
-The @code{gnunet-service-dns} will then start helper programs that will
-make the necessary changes to your firewall (@code{iptables}) rules.
-Note that this will NOT work if your system sends out DNS traffic to a
-link-local IPv6 address, as in this case GNUnet can intercept the traffic,
-but not inject the responses from the link-local IPv6 address. Hence you
-cannot use system-wide DNS interception in conjunction with link-local
-IPv6-based DNS servers. If such a DNS server is used, it will bypass
-GNUnet's DNS traffic interception.
-Using the GNU Name System (GNS) requires two different configuration
-steps.
-First of all, GNS needs to be integrated with the operating system. Most
-of this section is about the operating system level integration.
-The remainder of this chapter will detail the various methods for
-configuring the use of GNS with your operating system.
-At this point in time you have different options depending on your OS:
-@itemize @bullet
-@item Use the gnunet-gns-proxy@*
-This approach works for all operating systems and is likely the
-easiest. However, it enables GNS only for browsers, not for other
-applications that might be using DNS, such as SSH.  Still, using the
-proxy is required for using HTTP with GNS and is thus recommended for
-all users. To do this, you simply have to run the
-@code{gnunet-gns-proxy-setup-ca} script as the user who will run the
-browser (this will create a GNS certificate authority (CA) on your
-system and import its key into your browser), then start
-@code{gnunet-gns-proxy} and inform your browser to use the Socks5
-proxy which @code{gnunet-gns-proxy} makes available by default on port
-7777.
-@item Use a nsswitch plugin (recommended on GNU systems)@*
-This approach has the advantage of offering fully personalized
-resolution even on multi-user systems. A potential disadvantage is
-that some applications might be able to bypass GNS.
-@item Use a W32 resolver plugin (recommended on W32)@*
-This is currently the only option on W32 systems.
-@item Use system-wide DNS packet interception@*
-This approach is recommended for the GNUnet VPN. It can be used to
-handle GNS at the same time; however, if you only use this method, you
-will only get one root zone per machine (not so great for multi-user
-systems).
-@end itemize
-You can combine system-wide DNS packet interception with the nsswitch
-plugin.
-The setup of the system-wide DNS interception is described here. All of
-the other GNS-specific configuration steps are described in the following
-sections.
-@node Configuring the GNS nsswitch plugin
-@subsubsection Configuring the GNS nsswitch plugin
-The Name Service Switch (NSS) is a facility in Unix-like operating systems
-(in most cases provided by the GNU C Library)
-that provides a variety of sources for common configuration databases and
-name resolution mechanisms.
-A superuser (system administrator) usually configures the
-operating system's name services using the file
-@file{/etc/nsswitch.conf}.
-GNS provides a NSS plugin to integrate GNS name resolution with the
-operating system's name resolution process.
-To use the GNS NSS plugin you have to either
-@itemize @bullet
-@item install GNUnet as root or
-@item compile GNUnet with the @code{--with-sudo=yes} switch.
-@end itemize
-Name resolution is controlled by the @emph{hosts} section in the NSS
-configuration. By default this section first performs a lookup in the
-@file{/etc/hosts} file and then in DNS.
-The nsswitch file should contain a line similar to:
-@example
-hosts: files dns [NOTFOUND=return] mdns4_minimal mdns4
-@end example
-@noindent
-Here the GNS NSS plugin can be added to perform a GNS lookup before
-performing a DNS lookup.
-The GNS NSS plugin has to be added to the "hosts" section in
-@file{/etc/nsswitch.conf} file before DNS related plugins:
-@example
-...
-hosts: files gns [NOTFOUND=return] dns mdns4_minimal mdns4
-...
-@end example
-@noindent
-The @code{NOTFOUND=return} will ensure that if a @code{.gnu} name is not
-found in GNS it will not be queried in DNS.
-@c @node Configuring GNS on W32
-@c @subsubsection Configuring GNS on W32
-@c This document is a guide to configuring GNU Name System on W32-compatible
-@c platforms.
-@c After GNUnet is installed, run the w32nsp-install tool:
-@c @example
-@c w32nsp-install.exe libw32nsp-0.dll
-@c @end example
-@c @noindent
-@c ('0' is the library version of W32 NSP; it might increase in the future,
-@c change the invocation accordingly).
-@c This will install GNS namespace provider into the system and allow other
-@c applications to resolve names that end in '@strong{gnu}'
-@c and '@strong{zkey}'. Note that namespace provider requires
-@c gnunet-gns-helper-service-w32 to be running, as well as gns service
-@c itself (and its usual dependencies).
-@c Namespace provider is hardcoded to connect to @strong{127.0.0.1:5353},
-@c and this is where gnunet-gns-helper-service-w32 should be listening to
-@c (and is configured to listen to by default).
-@c To uninstall the provider, run:
-@c @example
-@c w32nsp-uninstall.exe
-@c @end example
-@c @noindent
-@c (uses provider GUID to uninstall it, does not need a dll name).
-@c Note that while MSDN claims that other applications will only be able to
-@c use the new namespace provider after re-starting, in reality they might
-@c stat to use it without that. Conversely, they might stop using the
-@c provider after it's been uninstalled, even if they were not re-started.
-@c W32 will not permit namespace provider library to be deleted or
-@c overwritten while the provider is installed, and while there is at least
-@c one process still using it (even after it was uninstalled).
-@node GNS Proxy Setup
-@subsubsection GNS Proxy Setup
-When using the GNU Name System (GNS) to browse the WWW, there are several
-issues that can be solved by adding the GNS Proxy to your setup:
-@itemize @bullet
-@item If the target website does not support GNS, it might assume that it
-is operating under some name in the legacy DNS system (such as
-example.com). It may then attempt to set cookies for that domain, and the
-web server might expect a @code{Host: example.com} header in the request
-from your browser.
-However, your browser might be using @code{example.gnu} for the
-@code{Host} header and might only accept (and send) cookies for
-@code{example.gnu}. The GNS Proxy will perform the necessary translations
-of the hostnames for cookies and HTTP headers (using the LEHO record for
-the target domain as the desired substitute).
-@item If using HTTPS, the target site might include an SSL certificate
-which is either only valid for the LEHO domain or might match a TLSA
-record in GNS. However, your browser would expect a valid certificate for
-@code{example.gnu}, not for some legacy domain name. The proxy will
-validate the certificate (either against LEHO or TLSA) and then
-on-the-fly produce a valid certificate for the exchange, signed by your
-own CA. Assuming you installed the CA of your proxy in your browser's
-certificate authority list, your browser will then trust the
-HTTPS/SSL/TLS connection, as the hostname mismatch is hidden by the proxy.
-@item Finally, the proxy will in the future indicate to the server that it
-speaks GNS, which will enable server operators to deliver GNS-enabled web
-sites to your browser (and continue to deliver legacy links to legacy
-browsers)
-@end itemize
-@node Setup of the GNS CA
-@subsubsection Setup of the GNS CA
-First you need to create a CA certificate that the proxy can use.
-To do so use the provided script gnunet-gns-proxy-ca:
-@example
-$ gnunet-gns-proxy-setup-ca
-@end example
-@noindent
-This will create a personal certification authority for you and add this
-authority to the firefox and chrome database. The proxy will use the this
-CA certificate to generate @code{*.gnu} client certificates on the fly.
-Note that the proxy uses libcurl. Make sure your version of libcurl uses
-GnuTLS and NOT OpenSSL. The proxy will @b{not} work with libcurl compiled
-against OpenSSL.
-You can check the configuration your libcurl was build with by
-running:
-@example
-curl --version
-@end example
-the output will look like this (without the linebreaks):
-@example
-gnurl --version
-curl 7.56.0 (x86_64-unknown-linux-gnu) libcurl/7.56.0 \
-GnuTLS/3.5.13 zlib/1.2.11 libidn2/2.0.4
-Release-Date: 2017-10-08
-Protocols: http https
-Features: AsynchDNS IDN IPv6 Largefile NTLM SSL libz \
-TLS-SRP UnixSockets HTTPS-proxy
-@end example
-@node Testing the GNS setup
-@subsubsection Testing the GNS setup
-Now for testing purposes we can create some records in our zone to test
-the SSL functionality of the proxy:
-@example
-$ gnunet-identity -C test
-$ gnunet-namestore -a -e "1 d" -n "homepage" \
-  -t A -V 131.159.74.67 -z test
-$ gnunet-namestore -a -e "1 d" -n "homepage" \
-  -t LEHO -V "gnunet.org" -z test
-@end example
-@noindent
-At this point we can start the proxy. Simply execute
-@example
-$ gnunet-arm -i gns-proxy
-@end example
-To run the proxy at all times in the future, you should
-change your configuration as follows:
-@example
-$ gnunet-config -s gns-proxy -o AUTOSTART -V YES
-@end example
-@noindent
-Configure your browser to use this SOCKSv5 proxy using
-@code{localhost} on port 7777.
-If you use @command{Firefox} (or one of its derivatives/forks such as
-Icecat) you also have to go to @code{about:config} and set the key
-@code{network.proxy.socks_remote_dns} to @code{true}.
-When you visit @code{https://homepage.test/}, you should get to the
-@code{https://gnunet.org/} frontpage and the browser (with the correctly
-configured proxy) should give you a valid SSL certificate for
-@code{homepage.gnu} and no warnings. It should look like this:
-@c FIXME: Image does not exist, create it or save it from Drupal?
-@c @image{images/gnunethpgns.png,5in,, picture of homepage.gnu in Webbrowser}
-@node Migrating existing DNS zones into GNS
-@subsubsection Migrating existing DNS zones into GNS
-To migrate an existing zone into GNS use the Ascension tool.
-Ascension transfers entire zones into GNS by doing incremental zone transfers
-and then adding the records to GNS.
-Compared to the gnunet-zoneimport tool it strictly uses AXFR or IXFR depending
-on whether or not there exists a SOA record for the zone. If that is the case it
-will take the serial as a reference point and request the zone. The server will
-either answer the IXFR request with a correct incremental zone or with the
-entire zone, which depends on the server configuration.
-You can find the source code here: @code{https://git.gnunet.org/ascension.git/}
-The software can be installed into a Python virtual environment like this:
-@example
-$ python3 -m venv .venv
-$ source .venv/bin/activate
-$ python3 setup.py install
-@end example
-Or installed globally like this:
-@example
-$ sudo python3 setup.py install
-@end example
-Pip will then install all the necessary requirements that are needed to run
-Ascension. For development purposes a virtual environment should suffice.
-Keeping a virtual environment helps with keeping things tidy and prevents
-breaking of Ascension through a future Python update.
-The advantage of using a virtual environment is, that all the dependencies can
-be installed separately in different versions without touching your systems
-Python installation and its dependencies.
-Another way to install Ascension on Debian is to install the python3-ascension
-package. It can be found within the above mentioned Ascension git repository.
-This also adds a system user called ascension and runs a GNUnet peer in the
-background. Please note: This only works if a recent version of GNUnet is
-installed on your system. The version number of Ascension is chosen according
-to the required feature level of GNUnet: Ascension 0.11.5 is only
-compatible with GNUnet 0.11.5 or later and so on.
-As Debian's packages for GNUnet are outdated even in experimental,
-you will need to install GNUnet manually
-@xref{Installing GNUnet}.
-Please check @xref{Migrating an existing DNS zone into GNS}, for usage manual
-of the tool.
-@node Configuring the GNUnet VPN
-@subsection Configuring the GNUnet VPN
-@menu
-* IPv4 address for interface::
-* IPv6 address for interface::
-* Configuring the GNUnet VPN DNS::
-* Configuring the GNUnet VPN Exit Service::
-* IP Address of external DNS resolver::
-* IPv4 address for Exit interface::
-* IPv6 address for Exit interface::
-@end menu
-Before configuring the GNUnet VPN, please make sure that system-wide DNS
-interception is configured properly as described in the section on the
-GNUnet DNS setup. @pxref{Configuring the GNU Name System},
-if you haven't done so already.
-The default options for the GNUnet VPN are usually sufficient to use
-GNUnet as a Layer 2 for your Internet connection.
-However, what you always have to specify is which IP protocol you want
-to tunnel: IPv4, IPv6 or both.
-Furthermore, if you tunnel both, you most likely should also tunnel
-all of your DNS requests.
-You theoretically can tunnel "only" your DNS traffic, but that usually
-makes little sense.
-The other options as shown on the gnunet-setup tool are:
-@node IPv4 address for interface
-@subsubsection IPv4 address for interface
-This is the IPv4 address the VPN interface will get. You should pick a
-'private' IPv4 network that is not yet in use for you system. For example,
-if you use @code{10.0.0.1/255.255.0.0} already, you might use
-@code{10.1.0.1/255.255.0.0}.
-If you use @code{10.0.0.1/255.0.0.0} already, then you might use
-@code{192.168.0.1/255.255.0.0}.
-If your system is not in a private IP-network, using any of the above will
-work fine.
-You should try to make the mask of the address big enough
-(@code{255.255.0.0} or, even better, @code{255.0.0.0}) to allow more
-mappings of remote IP Addresses into this range.
-However, even a @code{255.255.255.0} mask will suffice for most users.
-@node IPv6 address for interface
-@subsubsection IPv6 address for interface
-The IPv6 address the VPN interface will get. Here you can specify any
-non-link-local address (the address should not begin with @code{fe80:}).
-A subnet Unique Local Unicast (@code{fd00::/8} prefix) that you are
-currently not using would be a good choice.
-@node Configuring the GNUnet VPN DNS
-@subsubsection Configuring the GNUnet VPN DNS
-To resolve names for remote nodes, activate the DNS exit option.
-@node Configuring the GNUnet VPN Exit Service
-@subsubsection Configuring the GNUnet VPN Exit Service
-If you want to allow other users to share your Internet connection (yes,
-this may be dangerous, just as running a Tor exit node) or want to
-provide access to services on your host (this should be less dangerous,
-as long as those services are secure), you have to enable the GNUnet exit
-daemon.
-You then get to specify which exit functions you want to provide. By
-enabling the exit daemon, you will always automatically provide exit
-functions for manually configured local services (this component of the
-system is under
-development and not documented further at this time). As for those
-services you explicitly specify the target IP address and port, there is
-no significant security risk in doing so.
-Furthermore, you can serve as a DNS, IPv4 or IPv6 exit to the Internet.
-Being a DNS exit is usually pretty harmless. However, enabling IPv4 or
-IPv6-exit without further precautions may enable adversaries to access
-your local network, send spam, attack other systems from your Internet
-connection and do other mischiefs that will appear to come from your
-machine. This may or may not get you into legal trouble.
-If you want to allow IPv4 or IPv6-exit functionality, you should strongly
-consider adding additional firewall rules manually to protect your local
-network and to restrict outgoing TCP traffic (e.g. by not allowing access
-to port 25). While we plan to improve exit-filtering in the future,
-you're currently on your own here.
-Essentially, be prepared for any kind of IP-traffic to exit the respective
-TUN interface (and GNUnet will enable IP-forwarding and NAT for the
-interface automatically).
-Additional configuration options of the exit as shown by the gnunet-setup
-tool are:
-@node IP Address of external DNS resolver
-@subsubsection IP Address of external DNS resolver
-If DNS traffic is to exit your machine, it will be send to this DNS
-resolver. You can specify an IPv4 or IPv6 address.
-@node IPv4 address for Exit interface
-@subsubsection IPv4 address for Exit interface
-This is the IPv4 address the Interface will get. Make the mask of the
-address big enough (255.255.0.0 or, even better, 255.0.0.0) to allow more
-mappings of IP addresses into this range. As for the VPN interface, any
-unused, private IPv4 address range will do.
-@node IPv6 address for Exit interface
-@subsubsection IPv6 address for Exit interface
-The public IPv6 address the interface will get. If your kernel is not a
-very recent kernel and you are willing to manually enable IPv6-NAT, the
-IPv6 address you specify here must be a globally routed IPv6 address of
-your host.
-Suppose your host has the address @code{2001:4ca0::1234/64}, then
-using @code{2001:4ca0::1:0/112} would be fine (keep the first 64 bits,
-then change at least one bit in the range before the bitmask, in the
-example above we changed bit 111 from 0 to 1).
-You may also have to configure your router to route traffic for the entire
-subnet (@code{2001:4ca0::1:0/112} for example) through your computer (this
-should be automatic with IPv6, but obviously anything can be
-disabled).
-@node Bandwidth Configuration
-@subsection Bandwidth Configuration
-You can specify how many bandwidth GNUnet is allowed to use to receive
-and send data. This is important for users with limited bandwidth or
-traffic volume.
-@node Configuring NAT
-@subsection Configuring NAT
-Most hosts today do not have a normal global IP address but instead are
-behind a router performing Network Address Translation (NAT) which assigns
-each host in the local network a private IP address.
-As a result, these machines cannot trivially receive inbound connections
-from the Internet. GNUnet supports NAT traversal to enable these machines
-to receive incoming connections from other peers despite their
-limitations.
-In an ideal world, you can press the "Attempt automatic configuration"
-button in gnunet-setup to automatically configure your peer correctly.
-Alternatively, your distribution might have already triggered this
-automatic configuration during the installation process.
-However, automatic configuration can fail to determine the optimal
-settings, resulting in your peer either not receiving as many connections
-as possible, or in the worst case it not connecting to the network at all.
-To manually configure the peer, you need to know a few things about your
-network setup. First, determine if you are behind a NAT in the first
-place.
-This is always the case if your IP address starts with "10.*" or
-"192.168.*". Next, if you have control over your NAT router, you may
-choose to manually configure it to allow GNUnet traffic to your host.
-If you have configured your NAT to forward traffic on ports 2086 (and
-possibly 1080) to your host, you can check the "NAT ports have been opened
-manually" option, which corresponds to the "PUNCHED_NAT" option in the
-configuration file. If you did not punch your NAT box, it may still be
-configured to support UPnP, which allows GNUnet to automatically
-configure it. In that case, you need to install the "upnpc" command,
-enable UPnP (or PMP) on your NAT box and set the "Enable NAT traversal
-via UPnP or PMP" option (corresponding to "ENABLE_UPNP" in the
-configuration file).
-Some NAT boxes can be traversed using the autonomous NAT traversal method.
-This requires certain GNUnet components to be installed with "SUID"
-privileges on your system (so if you're installing on a system you do
-not have administrative rights to, this will not work).
-If you installed as 'root', you can enable autonomous NAT traversal by
-checking the "Enable NAT traversal using ICMP method".
-The ICMP method requires a way to determine your NAT's external (global)
-IP address. This can be done using either UPnP, DynDNS, or by manual
-configuration. If you have a DynDNS name or know your external IP address,
-you should enter that name under "External (public) IPv4 address" (which
-corresponds to the "EXTERNAL_ADDRESS" option in the configuration file).
-If you leave the option empty, GNUnet will try to determine your external
-IP address automatically (which may fail, in which case autonomous
-NAT traversal will then not work).
-Finally, if you yourself are not behind NAT but want to be able to
-connect to NATed peers using autonomous NAT traversal, you need to check
-the "Enable connecting to NATed peers using ICMP method" box.
-@node Peer configuration for distributors (e.g. Operating Systems)
-@subsection Peer configuration for distributors (e.g. Operating Systems)
-The "GNUNET_DATA_HOME" in "[PATHS]" in @file{/etc/gnunet.conf} should be
-manually set to "/var/lib/gnunet/data/" as the default
-"~/.local/share/gnunet/" is probably not that appropriate in this case.
-Similarly, distributors may consider pointing "GNUNET_RUNTIME_DIR" to
-"/var/run/gnunet/" and "GNUNET_HOME" to "/var/lib/gnunet/". Also, should a
-distributor decide to override system defaults, all of these changes
-should be done in a custom @file{/etc/gnunet.conf} and not in the files
-in the @file{config.d/} directory.
-Given the proposed access permissions, the "gnunet-setup" tool must be
-run as use "gnunet" (and with option "-c /etc/gnunet.conf" so that it
-modifies the system configuration). As always, gnunet-setup should be run
-after the GNUnet peer was stopped using "gnunet-arm -e". Distributors
-might want to include a wrapper for gnunet-setup that allows the
-desktop-user to "sudo" (e.g. using gtksudo) to the "gnunet" user account
-and then runs "gnunet-arm -e", "gnunet-setup" and "gnunet-arm -s" in
-sequence.
-@node Config Leftovers
-@section Config Leftovers
-This section describes how to start a GNUnet peer. It assumes that you
-have already compiled and installed GNUnet and its' dependencies.
-Before you start a GNUnet peer, you may want to create a configuration
-file using gnunet-setup (but you do not have to).
-Sane defaults should exist in your
-@file{$GNUNET_PREFIX/share/gnunet/config.d/} directory, so in practice
-you could simply start without any configuration. If you want to
-configure your peer later, you need to stop it before invoking the
-@code{gnunet-setup} tool to customize further and to test your
-configuration (@code{gnunet-setup} has built-in test functions).
-The most important option you might have to still set by hand is in
-[PATHS]. Here, you use the option "GNUNET_HOME" to specify the path where
-GNUnet should store its data.
-It defaults to @code{$HOME/}, which again should work for most users.
-Make sure that the directory specified as GNUNET_HOME is writable to
-the user that you will use to run GNUnet (note that you can run frontends
-using other users, GNUNET_HOME must only be accessible to the user used to
-run the background processes).
-You will also need to make one central decision: should all of GNUnet be
-run under your normal UID, or do you want distinguish between system-wide
-(user-independent) GNUnet services and personal GNUnet services. The
-multi-user setup is slightly more complicated, but also more secure and
-generally recommended.
-@menu
-* The Single-User Setup::
-* The Multi-User Setup::
-* Killing GNUnet services::
-* Access Control for GNUnet::
-@end menu
-@node The Single-User Setup
-@subsection The Single-User Setup
-For the single-user setup, you do not need to do anything special and can
-just start the GNUnet background processes using @code{gnunet-arm}.
-By default, GNUnet looks in @file{~/.config/gnunet.conf} for a
-configuration (or @code{$XDG_CONFIG_HOME/gnunet.conf} if@
-@code{$XDG_CONFIG_HOME} is defined). If your configuration lives
-elsewhere, you need to pass the @code{-c FILENAME} option to all GNUnet
-commands.
-Assuming the configuration file is called @file{~/.config/gnunet.conf},
-you start your peer using the @code{gnunet-arm} command (say as user
-@code{gnunet}) using:
-@example
-gnunet-arm -c ~/.config/gnunet.conf -s
-@end example
-@noindent
-The "-s" option here is for "start". The command should return almost
-instantly. If you want to stop GNUnet, you can use:
-@example
-gnunet-arm -c ~/.config/gnunet.conf -e
-@end example
-@noindent
-The "-e" option here is for "end".
-Note that this will only start the basic peer, no actual applications
-will be available.
-If you want to start the file-sharing service, use (after starting
-GNUnet):
-@example
-gnunet-arm -c ~/.config/gnunet.conf -i fs
-@end example
-@noindent
-The "-i fs" option here is for "initialize" the "fs" (file-sharing)
-application. You can also selectively kill only file-sharing support using
-@example
-gnunet-arm -c ~/.config/gnunet.conf -k fs
-@end example
-@noindent
-Assuming that you want certain services (like file-sharing) to be always
-automatically started whenever you start GNUnet, you can activate them by
-setting "IMMEDIATE_START=YES" in the respective section of the configuration
-file (for example, "[fs]"). Then GNUnet with file-sharing support would
-be started whenever you@ enter:
-@example
-gnunet-arm -c ~/.config/gnunet.conf -s
-@end example
-@noindent
-Alternatively, you can combine the two options:
-@example
-gnunet-arm -c ~/.config/gnunet.conf -s -i fs
-@end example
-@noindent
-Using @code{gnunet-arm} is also the preferred method for initializing
-GNUnet from @code{init}.
-Finally, you should edit your @code{crontab} (using the @code{crontab}
-command) and insert a line@
-@example
-@@reboot gnunet-arm -c ~/.config/gnunet.conf -s
-@end example
-to automatically start your peer whenever your system boots.
-@node The Multi-User Setup
-@subsection The Multi-User Setup
-This requires you to create a user @code{gnunet} and an additional group
-@code{gnunetdns}, prior to running @code{make install} during
-installation.
-Then, you create a configuration file @file{/etc/gnunet.conf} which should
-contain the lines:@
-@example
-[arm]
-START_SYSTEM_SERVICES = YES
-START_USER_SERVICES = NO
-@end example
-@noindent
-Then, perform the same steps to run GNUnet as in the per-user
-configuration, except as user @code{gnunet} (including the
-@code{crontab} installation).
-You may also want to run @code{gnunet-setup} to configure your peer
-(databases, etc.).
-Make sure to pass @code{-c /etc/gnunet.conf} to all commands. If you
-run @code{gnunet-setup} as user @code{gnunet}, you might need to change
-permissions on @file{/etc/gnunet.conf} so that the @code{gnunet} user can
-write to the file (during setup).
-Afterwards, you need to perform another setup step for each normal user
-account from which you want to access GNUnet. First, grant the normal user
-(@code{$USER}) permission to the group gnunet:
-@example
-# adduser $USER gnunet
-@end example
-@noindent
-Then, create a configuration file in @file{~/.config/gnunet.conf} for the
-$USER with the lines:
-@example
-[arm]
-START_SYSTEM_SERVICES = NO
-START_USER_SERVICES = YES
-@end example
-@noindent
-This will ensure that @code{gnunet-arm} when started by the normal user
-will only run services that are per-user, and otherwise rely on the
-system-wide services.
-Note that the normal user may run gnunet-setup, but the
-configuration would be ineffective as the system-wide services will use
-@file{/etc/gnunet.conf} and ignore options set by individual users.
-Again, each user should then start the peer using
-@file{gnunet-arm -s} --- and strongly consider adding logic to start
-the peer automatically to their crontab.
-Afterwards, you should see two (or more, if you have more than one USER)
-@code{gnunet-service-arm} processes running in your system.
-@node Killing GNUnet services
-@subsection Killing GNUnet services
-It is not necessary to stop GNUnet services explicitly when shutting
-down your computer.
-It should be noted that manually killing "most" of the
-@code{gnunet-service} processes is generally not a successful method for
-stopping a peer (since @code{gnunet-service-arm} will instantly restart
-them). The best way to explicitly stop a peer is using
-@code{gnunet-arm -e}; note that the per-user services may need to be
-terminated before the system-wide services will terminate normally.
-@node Access Control for GNUnet
-@subsection Access Control for GNUnet
-This chapter documents how we plan to make access control work within the
-GNUnet system for a typical peer. It should be read as a best-practice
-installation guide for advanced users and builders of binary
-distributions. The recommendations in this guide apply to POSIX-systems
-with full support for UNIX domain sockets only.
-Note that this is an advanced topic. The discussion presumes a very good
-understanding of users, groups and file permissions. Normal users on
-hosts with just a single user can just install GNUnet under their own
-account (and possibly allow the installer to use SUDO to grant additional
-permissions for special GNUnet tools that need additional rights).
-The discussion below largely applies to installations where multiple users
-share a system and to installations where the best possible security is
-paramount.
-A typical GNUnet system consists of components that fall into four
-categories:
-@table @asis
-@item User interfaces
-User interfaces are not security sensitive and are supposed to be run and
-used by normal system users.
-The GTK GUIs and most command-line programs fall into this category.
-Some command-line tools (like gnunet-transport) should be excluded as they
-offer low-level access that normal users should not need.
-@item System services and support tools
-System services should always run and offer services that can then be
-accessed by the normal users.
-System services do not require special permissions, but as they are not
-specific to a particular user, they probably should not run as a
-particular user. Also, there should typically only be one GNUnet peer per
-host. System services include the gnunet-service and gnunet-daemon
-programs; support tools include command-line programs such as gnunet-arm.
-@item Privileged helpers
-Some GNUnet components require root rights to open raw sockets or perform
-other special operations. These gnunet-helper binaries are typically
-installed SUID and run from services or daemons.
-@item Critical services
-Some GNUnet services (such as the DNS service) can manipulate the service
-in deep and possibly highly security sensitive ways. For example, the DNS
-service can be used to intercept and alter any DNS query originating from
-the local machine. Access to the APIs of these critical services and their
-privileged helpers must be tightly controlled.
-@end table
-@c FIXME: The titles of these chapters are too long in the index.
-@menu
-* Recommendation - Disable access to services via TCP::
-* Recommendation - Run most services as system user "gnunet"::
-* Recommendation - Control access to services using group "gnunet"::
-* Recommendation - Limit access to certain SUID binaries by group "gnunet"::
-* Recommendation - Limit access to critical gnunet-helper-dns to group "gnunetdns"::
-* Differences between "make install" and these recommendations::
-@end menu
-@node Recommendation - Disable access to services via TCP
-@subsubsection Recommendation - Disable access to services via TCP
-GNUnet services allow two types of access: via TCP socket or via UNIX
-domain socket.
-If the service is available via TCP, access control can only be
-implemented by restricting connections to a particular range of IP
-addresses.
-This is acceptable for non-critical services that are supposed to be
-available to all users on the local system or local network.
-However, as TCP is generally less efficient and it is rarely the case
-that a single GNUnet peer is supposed to serve an entire local network,
-the default configuration should disable TCP access to all GNUnet
-services on systems with support for UNIX domain sockets.
-Since GNUnet 0.9.2, configuration files with TCP access disabled should be
-generated by default. Users can re-enable TCP access to particular
-services simply by specifying a non-zero port number in the section of
-the respective service.
-@node Recommendation - Run most services as system user "gnunet"
-@subsubsection Recommendation - Run most services as system user "gnunet"
-GNUnet's main services should be run as a separate user "gnunet" in a
-special group "gnunet".
-The user "gnunet" should start the peer using "gnunet-arm -s" during
-system startup. The home directory for this user should be
-@file{/var/lib/gnunet} and the configuration file should be
-@file{/etc/gnunet.conf}.
-Only the @code{gnunet} user should have the right to access
-@file{/var/lib/gnunet} (@emph{mode: 700}).
-@node Recommendation - Control access to services using group "gnunet"
-@subsubsection Recommendation - Control access to services using group "gnunet"
-Users that should be allowed to use the GNUnet peer should be added to the
-group "gnunet". Using GNUnet's access control mechanism for UNIX domain
-sockets, those services that are considered useful to ordinary users
-should be made available by setting "UNIX_MATCH_GID=YES" for those
-services.
-Again, as shipped, GNUnet provides reasonable defaults.
-Permissions to access the transport and core subsystems might additionally
-be granted without necessarily causing security concerns.
-Some services, such as DNS, must NOT be made accessible to the "gnunet"
-group (and should thus only be accessible to the "gnunet" user and
-services running with this UID).
-@node Recommendation - Limit access to certain SUID binaries by group "gnunet"
-@subsubsection Recommendation - Limit access to certain SUID binaries by group "gnunet"
-Most of GNUnet's SUID binaries should be safe even if executed by normal
-users. However, it is possible to reduce the risk a little bit more by
-making these binaries owned by the group "gnunet" and restricting their
-execution to user of the group "gnunet" as well (4750).
-@node Recommendation - Limit access to critical gnunet-helper-dns to group "gnunetdns"
-@subsubsection Recommendation - Limit access to critical gnunet-helper-dns to group "gnunetdns"
-A special group "gnunetdns" should be created for controlling access to
-the "gnunet-helper-dns".
-The binary should then be owned by root and be in group "gnunetdns" and
-be installed SUID and only be group-executable (2750).
-@b{Note that the group "gnunetdns" should have no users in it at all,
-ever.}
-The "gnunet-service-dns" program should be executed by user "gnunet" (via
-gnunet-service-arm) with the binary owned by the user "root" and the group
-"gnunetdns" and be SGID (2700). This way, @strong{only}
-"gnunet-service-dns" can change its group to "gnunetdns" and execute the
-helper, and the helper can then run as root (as per SUID).
-Access to the API offered by "gnunet-service-dns" is in turn restricted
-to the user "gnunet" (not the group!), which means that only
-"benign" services can manipulate DNS queries using "gnunet-service-dns".
-@node Differences between "make install" and these recommendations
-@subsubsection Differences between "make install" and these recommendations
-The current build system does not set all permissions automatically based
-on the recommendations above. In particular, it does not use the group
-"gnunet" at all (so setting gnunet-helpers other than the
-gnunet-helper-dns to be owned by group "gnunet" must be done manually).
-Furthermore, 'make install' will silently fail to set the DNS binaries to
-be owned by group "gnunetdns" unless that group already exists (!).
-An alternative name for the "gnunetdns" group can be specified using the
-@code{--with-gnunetdns=GRPNAME} configure option.
diff --git a/doc/handbook/chapters/keyconcepts.texi b/doc/handbook/chapters/keyconcepts.texi
deleted file mode 100644
index c8dd1599b..000000000
--- a/doc/handbook/chapters/keyconcepts.texi
+++ /dev/null
@@ -1,350 +0,0 @@
-@cindex Key Concepts
-@node Key Concepts
-@chapter Key Concepts
-In this section, the fundamental concepts of GNUnet are explained.
-@c FIXME: Use @uref{https://docs.gnunet.org/bib/, research papers}
-@c once we have the new bibliography + subdomain setup.
-Most of them are also described in our research papers.
-First, some of the concepts used in the GNUnet framework are detailed.
-The second part describes concepts specific to anonymous file-sharing.
-@menu
-* Authentication::
-* Accounting to Encourage Resource Sharing::
-* Confidentiality::
-* Anonymity::
-* Deniability::
-* Peer Identities::
-* Zones in the GNU Name System (GNS Zones)::
-* Egos::
-@end menu
-@cindex Authentication
-@node Authentication
-@section Authentication
-Almost all peer-to-peer communications in GNUnet are between mutually
-authenticated peers. The authentication works by using ECDHE, that is a
-DH (Diffie---Hellman) key exchange using ephemeral elliptic curve
-cryptography. The ephemeral ECC (Elliptic Curve Cryptography) keys are
-signed using ECDSA (@uref{http://en.wikipedia.org/wiki/ECDSA, ECDSA}).
-The shared secret from ECDHE is used to create a pair of session keys
-@c FIXME: Long word for HKDF. More FIXMEs: Explain MITM etc.
-(using HKDF) which are then used to encrypt the communication between the
-two peers using both 256-bit AES (Advanced Encryption Standard)
-and 256-bit Twofish (with independently derived secret keys).
-As only the two participating hosts know the shared secret, this
-authenticates each packet
-without requiring signatures each time. GNUnet uses SHA-512
-(Secure Hash Algorithm) hash codes to verify the integrity of messages.
-@c FIXME: A while back I got the feedback that I should try and integrate
-@c explanation boxes in the long-run. So we could explain
-@c "man-in-the-middle" and "man-in-the-middle attacks" and other words
-@c which are not common knowledge. MITM is not common knowledge. To be
-@c selfcontained, we should be able to explain words and concepts used in
-@c a chapter or paragraph without hinting at Wikipedia and other online
-@c sources which might not be available or accessible to everyone.
-@c On the other hand we could write an introductionary chapter or book
-@c that we could then reference in each chapter, which sound like it
-@c could be more reusable.
-In GNUnet, the identity of a host is its public key. For that reason,
-man-in-the-middle attacks will not break the authentication or accounting
-goals. Essentially, for GNUnet, the IP of the host has nothing to do with
-the identity of the host. As the public key is the only thing that truly
-matters, faking an IP, a port or any other property of the underlying
-transport protocol is irrelevant. In fact, GNUnet peers can use
-multiple IPs (IPv4 and IPv6) on multiple ports --- or even not use the
-IP protocol at all (by running directly on layer 2).
-@c FIXME: "IP protocol" feels wrong, but could be what people expect, as
-@c IP is "the number" and "IP protocol" the protocol itself in general
-@c knowledge?
-@c NOTE: For consistency we will use @code{HELLO}s throughout this Manual.
-GNUnet uses a special type of message to communicate a binding between
-public (ECC) keys to their current network address. These messages are
-commonly called @code{HELLO}s or @code{peer advertisements}.
-They contain the public key of the peer and its current network
-addresses for various transport services.
-A transport service is a special kind of shared library that
-provides (possibly unreliable, out-of-order) message delivery between
-peers.
-For the UDP and TCP transport services, a network address is an IP and a
-port.
-GNUnet can also use other transports (HTTP, HTTPS, WLAN, etc.) which use
-various other forms of addresses. Note that any node can have many
-different active transport services at the same time,
-and each of these can have a different addresses.
-Binding messages expire after at most a week (the timeout can be
-shorter if the user configures the node appropriately).
-This expiration ensures that the network will eventually get rid of
-outdated advertisements.
-For more information, refer to the following paper:
-Ronaldo A. Ferreira, Christian Grothoff, and Paul Ruth.
-A Transport Layer Abstraction for Peer-to-Peer Networks
-Proceedings of the 3rd International Symposium on Cluster Computing
-and the Grid (GRID 2003), 2003.
-(@uref{https://git.gnunet.org/bibliography.git/plain/docs/transport.pdf, https://git.gnunet.org/bibliography.git/plain/docs/transport.pdf})
-@cindex Accounting to Encourage Resource Sharing
-@node Accounting to Encourage Resource Sharing
-@section Accounting to Encourage Resource Sharing
-Most distributed P2P networks suffer from a lack of defenses or
-precautions against attacks in the form of freeloading.
-While the intentions of an attacker and a freeloader are different, their
-effect on the network is the same; they both render it useless.
-Most simple attacks on networks such as @command{Gnutella}
-involve flooding the network with traffic, particularly
-with queries that are, in the worst case, multiplied by the network.
-In order to ensure that freeloaders or attackers have a minimal impact
-on the network, GNUnet's file-sharing implementation (@code{FS}) tries
-to distinguish good (contributing) nodes from malicious (freeloading)
-nodes. In GNUnet, every file-sharing node keeps track of the behavior
-of every other node it has been in contact with. Many requests
-(depending on the application) are transmitted with a priority (or
-importance) level.  That priority is used to establish how important
-the sender believes this request is. If a peer responds to an
-important request, the recipient will increase its trust in the
-responder: the responder contributed resources.  If a peer is too busy
-to answer all requests, it needs to prioritize.  For that, peers do
-not take the priorities of the requests received at face value.
-First, they check how much they trust the sender, and depending on
-that amount of trust they assign the request a (possibly lower)
-effective priority. Then, they drop the requests with the lowest
-effective priority to satisfy their resource constraints. This way,
-GNUnet's economic model ensures that nodes that are not currently
-considered to have a surplus in contributions will not be served if
-the network load is high.
-For more information, refer to the following paper:
-Christian Grothoff. An Excess-Based Economic Model for Resource
-Allocation in Peer-to-Peer Networks. Wirtschaftsinformatik, June 2003.
-(@uref{https://git.gnunet.org/bibliography.git/plain/docs/ebe.pdf, https://git.gnunet.org/bibliography.git/plain/docs/ebe.pdf})
-@cindex Confidentiality
-@node Confidentiality
-@section Confidentiality
-Adversaries (malicious, bad actors) outside of GNUnet are not supposed
-to know what kind of actions a peer is involved in. Only the specific
-neighbor of a peer that is the corresponding sender or recipient of a
-message may know its contents, and even then application protocols may
-place further restrictions on that knowledge.  In order to ensure
-confidentiality, GNUnet uses link encryption, that is each message
-exchanged between two peers is encrypted using a pair of keys only
-known to these two peers.  Encrypting traffic like this makes any kind
-of traffic analysis much harder. Naturally, for some applications, it
-may still be desirable if even neighbors cannot determine the concrete
-contents of a message.  In GNUnet, this problem is addressed by the
-specific application-level protocols. See for example the following
-sections @pxref{Anonymity}, @pxref{How file-sharing achieves Anonymity},
-and @pxref{Deniability}.
-@cindex Anonymity
-@node Anonymity
-@section Anonymity
-@menu
-* How file-sharing achieves Anonymity::
-* How messaging provides Anonymity::
-@end menu
-Providing anonymity for users is the central goal for the anonymous
-file-sharing application. Many other design decisions follow in the
-footsteps of this requirement.
-Anonymity is never absolute. While there are various
-scientific metrics
-(Claudia Díaz, Stefaan Seys, Joris Claessens,
-and Bart Preneel. Towards measuring anonymity.
-2002.
-(@uref{https://git.gnunet.org/bibliography.git/plain/docs/article-89.pdf, https://git.gnunet.org/bibliography.git/plain/docs/article-89.pdf}))
-that can help quantify the level of anonymity that a given mechanism
-provides, there is no such thing as "complete anonymity".
-GNUnet's file-sharing implementation allows users to select for each
-operation (publish, search, download) the desired level of anonymity.
-The metric used is based on the amount of cover traffic needed to hide
-the request.
-While there is no clear way to relate the amount of available cover
-traffic to traditional scientific metrics such as the anonymity set or
-information leakage, it is probably the best metric available to a
-peer with a purely local view of the world, in that it does not rely
-on unreliable external information or a particular adversary model.
-The default anonymity level is @code{1}, which uses anonymous routing
-but imposes no minimal requirements on cover traffic. It is possible
-to forego anonymity when this is not required. The anonymity level of
-@code{0} allows GNUnet to use more efficient, non-anonymous routing.
-@cindex How file-sharing achieves Anonymity
-@node How file-sharing achieves Anonymity
-@subsection How file-sharing achieves Anonymity
-Contrary to other designs, we do not believe that users achieve strong
-anonymity just because their requests are obfuscated by a couple of
-indirections. This is not sufficient if the adversary uses traffic
-analysis.
-The threat model used for anonymous file sharing in GNUnet assumes that
-the adversary is quite powerful.
-In particular, we assume that the adversary can see all the traffic on
-the Internet. And while we assume that the adversary
-can not break our encryption, we assume that the adversary has many
-participating nodes in the network and that it can thus see many of the
-node-to-node interactions since it controls some of the nodes.
-The system tries to achieve anonymity based on the idea that users can be
-anonymous if they can hide their actions in the traffic created by other
-users.
-Hiding actions in the traffic of other users requires participating in the
-traffic, bringing back the traditional technique of using indirection and
-source rewriting. Source rewriting is required to gain anonymity since
-otherwise an adversary could tell if a message originated from a host by
-looking at the source address. If all packets look like they originate
-from one node, the adversary can not tell which ones originate from that
-node and which ones were routed.
-Note that in this mindset, any node can decide to break the
-source-rewriting paradigm without violating the protocol, as this
-only reduces the amount of traffic that a node can hide its own traffic
-in.
-If we want to hide our actions in the traffic of other nodes, we must make
-our traffic indistinguishable from the traffic that we route for others.
-As our queries must have us as the receiver of the reply
-(otherwise they would be useless), we must put ourselves as the receiver
-of replies that actually go to other hosts; in other words, we must
-indirect replies.
-Unlike other systems, in anonymous file-sharing as implemented on top of
-GNUnet we do not have to indirect the replies if we don't think we need
-more traffic to hide our own actions.
-This increases the efficiency of the network as we can indirect less under
-higher load.
-Refer to the following paper for more:
-Krista Bennett and Christian Grothoff.
-GAP --- practical anonymous networking. In Proceedings of
-Designing Privacy Enhancing Technologies, 2003.
-(@uref{https://git.gnunet.org/bibliography.git/plain/docs/aff.pdf, https://git.gnunet.org/bibliography.git/plain/docs/aff.pdf})
-@cindex How messaging provides Anonymity
-@node How messaging provides Anonymity
-@subsection How messaging provides Anonymity
-While the file-sharing tries to achieve anonymity through hiding actions in 
-other traffic, the messaging service provides a weaker form of protection 
-against identification.
-The messaging service allows the use of an anonymous ego for the signing and
-verification process of messages instead of a unique ego. This anonymous ego is
-a publicly known key pair which is shared between all peers in GNUnet.
-Using this ego only ensures that individual messages alone can't identify its 
-sender inside of a messenger room. It should be clarified that the route of 
-the traffic for each message can still be tracked to identify the senders peer 
-inside of a messenger room if the threat agent controls certain peers hosting
-the room.
-Also opening a room in the messenger service will potentially match your peer 
-identity with the internal member identity from the messenger service. So
-despite using the anonymous ego you can reveal your peer identity. This means
-to decrease the chance of being identified, it is recommended to enter rooms but 
-you should not open them for others.
-@cindex Deniability
-@node Deniability
-@section Deniability
-Even if the user that downloads data and the server that provides data are
-anonymous, the intermediaries may still be targets. In particular, if the
-intermediaries can find out which queries or which content they are
-processing, a strong adversary could try to force them to censor
-certain materials.
-With the file-encoding used by GNUnet's anonymous file-sharing, this
-problem does not arise.
-The reason is that queries and replies are transmitted in
-an encrypted format such that intermediaries cannot tell what the query
-is for or what the content is about.  Mind that this is not the same
-encryption as the link-encryption between the nodes.  GNUnet has
-encryption on the network layer (link encryption, confidentiality,
-authentication) and again on the application layer (provided
-by @command{gnunet-publish}, @command{gnunet-download},
-@command{gnunet-search} and @command{gnunet-fs-gtk}).
-Refer to the following paper for more:
-Christian Grothoff, Krista Grothoff, Tzvetan Horozov,
-and Jussi T. Lindgren.
-An Encoding for Censorship-Resistant Sharing.
-2009.
-(@uref{https://git.gnunet.org/bibliography.git/plain/docs/ecrs.pdf, https://git.gnunet.org/bibliography.git/plain/docs/ecrs.pdf})
-@cindex Peer Identities
-@node Peer Identities
-@section Peer Identities
-Peer identities are used to identify peers in the network and are unique
-for each peer. The identity for a peer is simply its public key, which is
-generated along with a private key when the peer is started for the first
-time. While the identity is binary data, it is often expressed as an ASCII
-string. For example, the following is a peer identity as you might see it
-in various places:
-@example
-UAT1S6PMPITLBKSJ2DGV341JI6KF7B66AC4JVCN9811NNEGQLUN0
-@end example
-@noindent
-You can find your peer identity by running @command{gnunet-peerinfo -s}.
-@cindex Zones in the GNU Name System (GNS Zones)
-@node Zones in the GNU Name System (GNS Zones)
-@section Zones in the GNU Name System (GNS Zones)
-@c FIXME: Explain or link to an explanation of the concept of public keys
-@c and private keys.
-@c FIXME: Rewrite for the latest GNS changes.
-GNS zones are similar to those of DNS zones, but instead of a hierarchy of
-authorities to governing their use, GNS zones are controlled by a private
-key.
-When you create a record in a DNS zone, that information is stored in your
-nameserver. Anyone trying to resolve your domain then gets pointed
-(hopefully) by the centralised authority to your nameserver.
-Whereas GNS, being fully decentralized by design, stores that information
-in DHT. The validity of the records is assured cryptographically, by
-signing them with the private key of the respective zone.
-Anyone trying to resolve records in a zone of your domain can then verify
-the signature of the records they get from the DHT and be assured that
-they are indeed from the respective zone.
-To make this work, there is a 1:1 correspondence between zones and
-their public-private key pairs.
-So when we talk about the owner of a GNS zone, that's really the owner of
-the private key.
-And a user accessing a zone needs to somehow specify the corresponding
-public key first.
-For more information, refer to the following paper:
-Matthias Wachs, Martin Schanzenbach, and Christian Grothoff.
-A Censorship-Resistant, Privacy-Enhancing and Fully Decentralized Name
-System. In proceedings of 13th International Conference on Cryptology and
-Network Security (CANS 2014). 2014.
-@uref{https://git.gnunet.org/bibliography.git/plain/docs/gns2014wachs.pdf, https://git.gnunet.org/bibliography.git/plain/docs/gns2014wachs.pdf}
-@cindex Egos
-@node Egos
-@section Egos
-@c what is the difference between peer identity and egos? It seems
-@c like both are linked to public-private key pair.
-Egos are your "identities" in GNUnet. Any user can assume multiple
-identities, for example to separate their activities online. Egos can
-correspond to "pseudonyms" or "real-world identities". Technically an
-ego is first of all a key pair of a public- and private-key.
diff --git a/doc/handbook/chapters/philosophy.texi b/doc/handbook/chapters/philosophy.texi
deleted file mode 100644
index 180589829..000000000
--- a/doc/handbook/chapters/philosophy.texi
+++ /dev/null
@@ -1,82 +0,0 @@
-@cindex Philosophy
-@node Philosophy
-@chapter Philosophy
-@c NOTE: We should probably re-use some of the images lynX created
-@c for secushare, showing some of the relations and functionalities
-@c of GNUnet.
-The primary goal of the GNUnet project is to provide a reliable, open,
-non-discriminating and censorship-resistant system for information
-exchange.
-We value free speech above state interests and intellectual
-monopoly. GNUnet's long-term goal is to serve as a development
-platform for the next generation of Internet protocols.
-Participants are encouraged to
-contribute at least as much resources (storage, bandwidth) to the network
-as they consume, so that their participation does not have a negative
-impact on other users.
-@menu
-* Design Principles::
-* Privacy and Anonymity::
-* Practicality::
-@end menu
-@cindex Design Principles
-@node Design Principles
-@section Design Principles
-These are the GNUnet design principles, in order of importance:
-@itemize
-@item GNUnet must be implemented as
-@uref{https://www.gnu.org/philosophy/free-sw.html, Free Software} ---
-This means that you have the four essential freedoms: to run
-the program, to study and change the program in source code form,
-to redistribute exact copies, and to distribute modified versions.
-(@uref{https://www.gnu.org/philosophy/free-sw.html}).
-@item GNUnet must minimize the amount of personally identifiable information exposed.
-@item GNUnet must be fully distributed and resilient to external attacks and rogue participants.
-@item GNUnet must be self-organizing and not depend on administrators or centralized infrastructure.
-@item GNUnet must inform the user which other participants have to be trusted when establishing private communications.
-@item GNUnet must be open and permit new peers to join.
-@item GNUnet must support a diverse range of applications and devices.
-@item GNUnet must use compartmentalization to protect sensitive information.
-@item The GNUnet architecture must be resource efficient.
-@item GNUnet must provide incentives for peers to contribute more resources than they consume.
-@end itemize
-@cindex Privacy and Anonymity
-@node Privacy and Anonymity
-@section Privacy and Anonymity
-The GNUnet protocols minimize the leakage of personally identifiable
-information of participants and do not allow adversaries to control,
-track, monitor or censor users activities. The GNUnet protocols also
-make it as hard as possible to disrupt operations by participating in
-the network with malicious intent.
-Analyzing participant's activities becomes more difficult as the
-number of peers and applications that generate traffic on the network
-grows, even if the additional traffic generated is not related to
-anonymous communication. This is one of the reasons why GNUnet is
-developed as a peer-to-peer framework where many applications share
-the lower layers of an increasingly complex protocol stack. The GNUnet
-architecture encourages many different forms of peer-to-peer
-applications.
-@cindex Practicality
-@node Practicality
-@section Practicality
-Wherever possible GNUnet allows the peer to adjust its operations and
-functionalities to specific use cases. A GNUnet peer running on a
-mobile device with limited battery for example might choose not to
-relay traffic for other participants.
-For certain applications like file-sharing GNUnet allows participants
-to trade degrees of anonymity in exchange for increased
-efficiency. However, it is not possible for any user's efficiency
-requirements to compromise the anonymity of any other user.
diff --git a/doc/handbook/chapters/preface.texi b/doc/handbook/chapters/preface.texi
deleted file mode 100644
index 961ec0737..000000000
--- a/doc/handbook/chapters/preface.texi
+++ /dev/null
@@ -1,212 +0,0 @@
-@node Preface
-@chapter Preface
-@c FIXME: Do we have to mention that this is Free Software?
-@c FIXME: where did 'Free Software' in this sentence fit before
-@c FIXME: we changed it?
-This collection of manuals describes GNUnet, a framework
-for secure peer-to-peer networking with the high-level goal to provide
-a strong foundation for a global, distributed network
-that provides security and privacy.
-GNUnet in that sense aims to replace the current Internet protocol stack.
-Along with an application for secure publication of files, it has grown to
-include all kinds of basic applications for the foundation of a new
-Internet.
-@menu
-* About this book::
-* Contributing to this book::
-* Introduction::
-* Project governance::
-* Typography::
-@end menu
-@node About this book
-@section About this book
-The books (described as ``book'' or ``books'' in the following)
-bundled as the ``GNUnet Reference Manual'' are based on the historic
-work of all contributors to previous documentation of GNUnet.
-It is our hope
-that the content is described in a way that does not require any
-academic background, although some concepts will require further
-reading.
-Our (long-term) goal with these books is to keep them
-self-contained. If you see references to Wikipedia and other external
-sources (except for our academic papers) it means that we are working
-on a solution to describe the explanations found there which fits our
-use-case and licensing.
-Previously the documentation was contained in Drupal books, on the
-old website. This format was considered unmaintainable for the future, so
-Texinfo was chosen. You might find old and very old sections in
-here in addition to more recent content. It took a long time to
-finish the move to Texinfo (from Drupal to LaTeX to wrong Texinfo
-output dump to good Texinfo) and only recently (late 2018, early
-2019) content checking started. We apologize to the reader for
-any inconvenience and hope you apply logic where bad advice from
-10 years ago can be found (pipe to sudo to install software is
-one example). Patches (contributions) to this documentation are more
-than welcome!
-The first chapter (``Preface'') as well as the second chapter
-(``Philosophy'') give an introduction to GNUnet as a project, what
-GNUnet tries to achieve. ``Key Concepts'' explains the key concepts
-in GNUnet.
-These three chapters are the most complete in the documentation.
-They are followed by chapters which explain specific parts of
-GNUnet (and need more work):
-``Installing GNUnet'', ``GNUnet Contributors Handbook'' and
-``GNUnet Developer Handbook''.
-@node Contributing to this book
-@section Contributing to this book
-@c FIXME: There's a good amount of repetition here, we should
-@c FIXME: fix this.
-The GNUnet Reference Manual is a collective work produced by various
-people throughout the years.
-The version you are reading is derived
-from many individual efforts hosted on one of our old websites.
-In the end it was considered to be impractical to read by
-those who required the information.
-With the conversion to Texinfo --- the version you are reading
-right now --- we hope to address this in the longterm.
-Texinfo is the documentation language of the GNU project.
-While it can be intimidating at first and look scary or complicated,
-it is just another way to express text format instructions.
-We encourage you to take this opportunity and learn about Texinfo,
-learn about GNUnet, and one word at a time we will arrive at a
-book which explains GNUnet in the least complicated way to you.
-Even when you don't want to or can't learn Texinfo, you can contribute.
-Send us an Email or join our IRC chat room on freenode and talk with
-us about the documentation (the preferred way to reach out is the
-mailinglist, since you can communicate with us without waiting on
-someone in the chatroom).
-One way or another you can help shape the understanding of GNUnet
-without the ability to read and understand its sourcecode.
-@node Introduction
-@section Introduction
-GNUnet in its current version is the result of almost 20 years of work
-from many contributors.  So far, most contributions were made by
-volunteers or people paid to do fundamental research.  At this stage,
-GNUnet remains an experimental system where
-significant parts of the software lack a reasonable degree of
-professionalism in its implementation.  Furthermore, we are aware of a
-significant number of existing bugs and critical design flaws, as some
-unfortunate early design decisions remain to be rectified.  There are
-still known open problems; GNUnet remains an active research project.
-The project was started in 2001 when some initial ideas for improving
-Freenet's file-sharing turned out to be too radical to be easily
-realized within the scope of the existing Freenet project.  We lost
-our first contributor on 11.9.2001 as the contributor realized that
-privacy may help terrorists.  The rest of the team concluded that it
-was now even more important to fight for civil liberties.  The first
-release was called ``GNet'' -- already with the name GNUnet in mind,
-but without the blessing of GNU we did not dare to call it GNUnet
-immediately.  A few months after the first release we contacted the
-GNU project, happily agreed to their governance model and became an
-official GNU package.
-Within the first year, we created
-@uref{https://gnu.org/s/libextractor, GNU libextractor}, a helper library
-for meta data extraction which has been used by a few other projects
-as well.  2003 saw the emergence of pluggable transports, the ability
-for GNUnet to use different mechanisms for communication, starting
-with TCP, UDP and SMTP (support for the latter was later dropped due
-to a lack of maintenance).  In 2005, the project first started to
-evolve beyond the original file-sharing application with a first
-simple P2P chat.  In 2007, we created
-@uref{https://gnu.org/s/libmicrohttpd, GNU libmicrohttpd}
-to support a pluggable transport based on HTTP.  In 2009, the
-architecture was radically modularized into the multi-process system
-that exists today.  Coincidentally, the first version of the ARM
-service (ARM: Automatic Restart Manager)
-was implemented a day before systemd was announced.  From 2009
-to 2014 work progressed rapidly thanks to a significant research grant
-from the Deutsche Forschungsgesellschaft.  This resulted in particular
-in the creation of the R5N DHT, CADET, ATS and the GNU Name System.
-In 2010, GNUnet was selected as the basis for the
-@uref{https://secushare.org, secushare} online
-social network, resulting in a significant growth of the core team.
-In 2013, we launched @uref{https://taler.net, GNU Taler} to address
-the challenge of convenient
-and privacy-preserving online payments.  In 2015, the
-@c XXX: It is not correct to refer to pEp as pEp stylistic,
-@c XXX: but the correct version would lead to problems with
-@c XXX: some of our outputs and/or older versions of texinfo
-@c XXX: and devices that display versions on consoles etc.
-@c XXX: This is why we keep the pEp until proven that p(triple bar)p
-@c XXX: does not create broken outputs.
-@uref{https://pep.foundation/, pretty Easy privacy} (pEp) project
-announced that they will use GNUnet as the technology for their
-meta-data protection layer, ultimately resulting in GNUnet e.V.
-entering into a formal long-term collaboration with the pEp
-Foundation.  In 2016, Taler Systems SA, a first startup using GNUnet
-technology, was founded with support from the community.
-GNUnet is not merely a technical project, but also a political
-mission: like the GNU project as a whole, we are writing software to
-achieve political goals with a focus on the human right of
-informational self-determination.  Putting users in control of their
-computing has been the core driver of the GNU project. With GNUnet we
-are focusing on informational self-determination for collaborative
-computing and communication over networks.
-The Internet is shaped as much by code and protocols as it is by its
-associated political processes (IETF, ICANN, IEEE, etc.).
-Similarly its flaws are not limited to the protocol design.  Thus,
-technical excellence by itself will not suffice to create a better
-network. We also need to build a community that is wise, humble and
-has a sense of humor to achieve our goal to create a technical
-foundation for a society we would like to live in.
-@node Project governance
-@section Project governance
-GNUnet, like the GNU project and many other free software projects,
-follows the governance model of a benevolent dictator.  This means
-that ultimately, the GNU project appoints the GNU maintainer and can
-overrule decisions made by the GNUnet maintainer. Similarly, the
-GNUnet maintainer can overrule any decisions made by individual
-developers.  Still, in practice neither has happened in the last 20
-years for GNUnet, and we hope to keep it that way.
-The current maintainers of GNUnet are:
-@itemize @bullet
-@item @uref{https://grothoff.org/christian/, Christian Grothoff}
-@item @uref{https://schanzen.eu, Martin Schanzenbach}
-@end itemize
-The GNUnet project is supported by GNUnet e.V., a German association
-where any developer can become a member.  GNUnet e.V. serves as a
-legal entity to hold the copyrights to GNUnet.  GNUnet e.V. may also
-choose to pay for project resources, and can collect donations as
-well as choose to adjust the license of the
-software (with the constraint that it has to remain free software).
-In 2018 we switched from GPL3 to AGPL3, in practice these changes do
-not happen very often.
-@node Typography
-@section Typography
-When giving examples for commands, shell prompts are used to show if the
-command should/can be issued as root, or if "normal" user privileges are
-sufficient. We use a @code{#} for root's shell prompt, a
-@code{%} for users' shell prompt, assuming they use the C-shell or tcsh
-and a @code{$} for bourne shell and derivatives.
-@c TODO: Really? Why the different prompts? Do we already have c-shell
-@c TODO: examples?
diff --git a/doc/handbook/chapters/user.texi b/doc/handbook/chapters/user.texi
deleted file mode 100644
index 714336228..000000000
--- a/doc/handbook/chapters/user.texi
+++ /dev/null
@@ -1,2603 +0,0 @@
-@node Using GNUnet
-@chapter Using GNUnet
-This tutorial is supposed to give a first introduction for users
-trying to do something real with GNUnet. Installation and
-configuration are specifically outside of the scope of this tutorial.
-Instead, we start by briefly checking that the installation works, and
-then dive into uncomplicated, concrete practical things that can be done
-with the framework provided by GNUnet.
-In short, this chapter of the ``GNUnet Reference Documentation'' will
-show you how to use the various peer-to-peer applications of the
-GNUnet system.
-As GNUnet evolves, we will add new sections for the various
-applications that are being created.
-Comments on the content of this chapter, and extensions of it are
-always welcome.
-@menu
-* Start and stop GNUnet::
-* First steps - Using the GNU Name System::
-* First steps - Using GNUnet Conversation::
-* First steps - Using the GNUnet VPN::
-* File-sharing::
-* The GNU Name System::
-* reclaimID Identity Provider::
-* Using the Virtual Public Network::
-* Using the GNUnet Messenger::
-@end menu
-@node Start and stop GNUnet
-@section Start and stop GNUnet
-Prior to using any GNUnet-based application, one has to start a node:
-@example
-$ gnunet-arm -s -l gnunet.log
-@end example
-To stop GNUnet:
-@example
-$ gnunet-arm -e
-@end example
-@node First steps - Using the GNU Name System
-@section First steps - Using the GNU Name System
-@menu
-* Preliminaries::
-* Managing Egos::
-* The GNS Tab::
-* Creating a Record::
-* Resolving GNS records::
-* Integration with Browsers (DNS2GNS service)::
-* Integration with Browsers (SOCKS proxy)::
-* Creating a Business Card::
-* Be Social::
-* Backup of Identities and Egos::
-* Revocation::
-* What's Next?::
-@end menu
-@node Preliminaries
-@subsection Preliminaries
-In the default configuration, there are two zones defined and shipped with
-GNUnet:
-The first is ``gnunet.org'', which points to the authoritate zone of the
-GNUnet project. It can be used to resolve, for example, ``www.gnunet.org''.
-``.pin'' is another default zone which points to a special zone also  managed
-by gnunet.org. Users may register submodomains on a first-come first-served-basis
-at @url{https://fcfs.gnunet.org}.
-Use @code{gnunet-config -s gns} to view the GNS configuration, including
-all configured zones that are operated by other users.  The respective
-configuration entry names start with a ``.'', e.g. ``.pin''.
-You can configure any number of top-level domains, and point them to
-the respective zones of your friends!  For this, simply obtain the
-respective public key (you will learn how below) and extend the
-configuration:
-@example
-$ gnunet-config -s gns -o .myfriend -V PUBLIC_KEY
-@end example
-@node Managing Egos
-@subsection Managing Egos
-In GNUnet, identity management is about managing egos.  Egos can
-correspond to pseudonyms or real-world identities.  If you value your
-privacy, you are encouraged to use separate egos for separate
-activities.
-Technically, an ego is first of all a public-private key pair, and
-thus egos also always correspond to a GNS zone.  Egos are managed by
-the IDENTITY service.  Note that this service has nothing to do with
-the peer identity.  The IDENTITY service essentially stores the
-private keys under human-readable names, and keeps a mapping of which
-private key should be used for particular important system functions.
-The existing identities can be listed using the command
-@command{gnunet-identity --display}
-@example
-gnu - JTDVJC69NHU6GQS4B5721MV8VM7J6G2DVRGJV0ONIT6QH7OI6D50
-rules - GO0T87F9BPMF8NKD5A54L2AH1T0GRML539TPFSRMCEA98182QD30
-@end example
-@node The GNS Tab
-@subsection The GNS Tab
-Maintaining your zones is through the NAMESTORE service and is discussed
-here.  You can manage your zone using @command{gnunet-identity} and
-@command{gnunet-namestore}, or most conveniently using
-@command{gnunet-namestore-gtk}.
-We will use the GTK+ interface in this introduction.  Please start
-@command{gnunet-gkt} and switch to the GNS tab, which is the tab in
-the middle with the letters "GNS" connected by a graph.
-Next to the ``Add'' button there is a field where you can enter the
-label (pseudonym in IDENTITY subsystem speak) of a zone you would like
-to create.  Pushing the ``Add'' button will create the zone.
-Afterwards, you can change the label in the combo box below at any
-time.  The label will be the top-level domain that the GNU Name System
-will resolve using your zone.  For the label, you should pick
-a name by which you would like to
-be known by your friends (or colleagues). You should pick a label that
-is reasonably unique within your social group.  Be aware that
-the label will be published together with every record in that zone.
-Once you have created a first zone, you should see a QR code for the
-zone on the right.  Next to it is a "Copy" button to copy the public
-key string to the clipboard. You can also save the QR code image to
-disk.
-Furthermore, you now can see the bottom part of the dialog.  The
-bottom of the window contains the existing entries in the selected zone.
-@node Creating a Record
-@subsection Creating a Record
-We will begin by creating a simple record in your master zone.
-To do this, click on the text "<new name>" in the table. The field is
-editable, allowing you to enter a fresh label. Labels are restricted
-to 63 characters and must not contain dots. For now, simply enter
-"test", then press ENTER to confirm. This will create a new (empty)
-record group under the label "test". Now click on "<new record>" next
-to the new label "test". In the drop-down menu, select "A" and push
-ENTER to confirm. Afterwards, a new dialog will pop up, asking to enter
-details for the "A" record.
-"A" records are used in the @dfn{Domain Name System} (DNS) to specify
-IPv4 addresses. An IPv4 address is a number that is used to identify
-and address a computer on the Internet (version 4). Please enter
-"217.92.15.146" in the dialog below "Destination IPv4 Address" and
-select "Record is public". Do not change any of the other options.
-Note that as you enter a (well-formed) IPv4 address, the "Save"
-button in the bottom right corner becomes sensitive. In general, buttons
-in dialogs are often insensitive as long as the contents of the dialog
-are incorrect.
-Once finished, press the "Save" button. Back in the main dialog, select
-the tiny triangle left of the "test" label. By doing so, you get to see
-all of the records under "test". Note that you can right-click a record
-to edit it later.
-@node Resolving GNS records
-@subsection Resolving GNS records
-Next, you should try resolving your own GNS records.  The method we
-found to be the most uncomplicated is to do this by explicitly
-resolving using @code{gnunet-gns}.  For this exercise, we will assume
-that you used the string ``gnu'' for the pseudonym (or label) of your
-GNS zone.  If you used something else, replace ``.gnu'' with your real
-pseudonym in the examples below.
-In the shell, type:
-@example
-$ gnunet-gns -u test.gnu # what follows is the reply
-test.gnu:
-Got `A' record: 217.92.15.146
-@end example
-@noindent
-That shows that resolution works, once GNS is integrated with
-the application.
-@node Integration with Browsers (DNS2GNS service)
-@subsection Integration with Browsers (DNS2GNS service)
-Most OSes allow you to either modify your @code{/etc/resolv.conf} directly or
-through @code{resolvectl}.
-We are going to configure the @code{dns2gns} service in order to translate DNS name
-queries by applications to GNS name queries where applicable and else fall back
-to DNS.
-Optionally, you may want to configure your @code{dns2gns} service to run on a
-non-priviledged port like 5353.
-But, in case you are going to edit @code{/etc/resolv.conf} directly, the
-@code{dns2gns} service MUST run on port 53 as you cannot specify the port number.
-A $FALLBACK_DNS variable should be a DNS server you trust such as your local router:
-@example
-$ gnunet-config -s dns2gns -o OPTIONS -V "-d $FALLBACK_DNS -p 5252"
-$ gnunet-arm -i dns2gns # Make sure the service is started
-@end example
-If you edit your resolv.conf directly, it should contain and entry like this:
-@example
-nameserver 127.0.0.1
-@end example
-In any case, it is very likely that the method of modification of your
-resolver is OS specific.
-Recently, the combination of NetworkManager and systemd-resolved is becoming
-increasingly popular.
-If you use resolvectl and systemd-resolved you can temporarily
-set the nameserver like this:
-@example
-$ resolvectl $INTERFACE 127.0.0.1:5353
-@end example
-Where @code{$INTERFACE} is your network interface such as ``eth0''.
-In order to automatically set the DNS2GNS server if it is running already you
-can use NetworkManager-dispatcher. First, enable it:
-@example
-$ sudo systemctl enable NetworkManager-dispatcher.service
-$ sudo systemctl start NetworkManager-dispatcher.service
-@end example
-Then, create a script /etc/NetworkManager/dispatch.h/10-dns2-gns.sh:
-@example
-#!/bin/sh
-interface=$1
-status=$2
-if [ "$interface" = "eth0" ]; then
-  case $status in
-    up)
-      if nc -u -z 127.0.0.1 5353; then
-      resolvectl dns $interface 127.0.0.1:5353
-    fi
-    ;;
-    down)
-    ;;
-  esac
-fi
-@end example
-Make sure the script is owned by root and executable:
-@example
-$ sudo root:root /etc/NetworkManager/dispatch.d/10-dns2gns.sh
-$ sudo +x /etc/NetworkManager/dispatch.d/10-dns2gns.sh
-@end example
-You can test accessing this website using your browser or curl:
-@example
-$ curl www.gnunet.org
-@end example
-Note that ``gnunet.org'' is a domain that also exists in DNS and for which the
-GNUnet project webservers can provide trusted TLS certificates.
-When using non-DNS names with GNS or aliases, this may result in issues
-when accessing HTTPS websites with browsers.
-In order learn how to provide relief for this issue, read on.
-@node Integration with Browsers (SOCKS proxy)
-@subsection Integration with Browsers (SOCKS proxy)
-While we recommend integrating GNS using the DNS2GNS service or the
-NSSwitch plugin, you can also
-integrate GNS directly with your browser via the @code{gnunet-gns-proxy}.
-This method can have the advantage that the proxy can validate
-TLS/X.509 records and thus strengthen web security; however, the proxy
-is still a bit brittle, so expect subtle failures. We have had reasonable
-success with Chromium, and various frustrations with Firefox in this area
-recently.
-The first step is to start the proxy. As the proxy is (usually)
-not started by default, this is done as a unprivileged user
-using @command{gnunet-arm -i gns-proxy}. Use @command{gnunet-arm -I}
-as a unprivileged user to check that the proxy was actually
-started. (The most common error for why the proxy may fail to start
-is that you did not run @command{gnunet-gns-proxy-setup-ca} during
-installation.) The proxy is a SOCKS5 proxy running (by default)
-on port 7777. Thus, you need to now configure your browser to use
-this proxy. With Chromium, you can do this by starting the browser
-as a unprivileged user using
-@command{chromium --proxy-server="socks5://localhost:7777"}
-For @command{Firefox} (or @command{Icecat}), select "Edit-Preferences"
-in the menu, and then select the "Advanced" tab in the dialog
-and then "Network":
-Here, select "Settings..." to open the proxy settings dialog.
-Select "Manual proxy configuration" and enter @code{localhost}
-with port 7777 under SOCKS Host.  Furthermore, set the
-checkbox ``Proxy DNS when using SOCKS v5'' at the bottom of
-the dialog.  Finally, push "OK".
-You must also go to about:config and change the
-@code{browser.fixup.alternate.enabled} option to @code{false},
-otherwise the browser will autoblunder an address like
-@code{@uref{http://www.gnu/, www.gnu}} to
-@code{@uref{http://www.gnu.com/, www.gnu.com}}.  If you want
-to resolve @@ in your own TLDs, you must additionally
-set @code{browser.fixup.dns_first_use_for_single_words} to @code{true}.
-After configuring your browser, you might want to first confirm that it
-continues to work as before. (The proxy is still experimental and if you
-experience "odd" failures with some webpages, you might want to disable
-it again temporarily.) Next, test if things work by typing
-"@uref{http://test.gnu/}" into the URL bar of your browser.
-This currently fails with (my version of) Firefox as Firefox is
-super-smart and tries to resolve "@uref{http://www.test.gnu/}" instead of
-"@uref{test.gnu}". Chromium can be convinced to comply if you explicitly
-include the "http://" prefix --- otherwise a Google search might be
-attempted, which is not what you want. If successful, you should
-see a simple website.
-Note that while you can use GNS to access ordinary websites, this is
-more an experimental feature and not really our primary goal at this
-time. Still, it is a possible use-case and we welcome help with testing
-and development.
-@pindex gnunet-bcd
-@node Creating a Business Card
-@subsection Creating a Business Card
-@c FIXME: Which parts of texlive are needed? Some systems offer a modular
-@c texlive (smaller size).
-Before we can really use GNS, you should create a business card.
-Note that this requires having @command{LaTeX} installed on your system.
-If you are using a Debian GNU/Linux based operating system, the
-following command should install the required components.
-Keep in mind that this @b{requires 3GB} of downloaded data and possibly
-@b{even more} when unpacked. On a GNU Guix based system texlive 2017 has
-returns a DAG size of 5032.4 MiB.
-The packages which are confirmed to be required are:
-@itemize @bullet
-@item texlive-units
-@item texlive-labels
-@item texlive-pst-barcode
-@item texlive-luatex85
-@item texlive-preview
-@item texlive-pdfcrop
-@item texlive-koma-script
-@end itemize
-@b{We welcome any help in identifying the required components of the
-TexLive Distribution. This way we could just state the required components
-without pulling in the full distribution of TexLive.}
-@example
-apt-get install texlive-full
-@end example
-@noindent
-Start creating a business card by clicking the "Copy" button
-in @command{gnunet-namestore-gtk}. Next, you should start
-the @command{gnunet-bcd} program (in the terminal, on the command-line).
-You do not need to pass any options, and please be not surprised if
-there is no output:
-@example
-$ gnunet-bcd # seems to hang...
-@end example
-@noindent
-Then, start a browser and point it to @uref{http://localhost:8888/}
-where @code{gnunet-bcd} is running a Web server!
-First, you might want to fill in the "GNS Public Key" field by
-right-clicking and selecting "Paste", filling in the public key
-from the copy you made in @command{gnunet-namestore-gtk}.
-Then, fill in all of the other fields, including your @b{GNS NICKname}.
-Adding a GPG fingerprint is optional.
-Once finished, click "Submit Query".
-If your @code{LaTeX} installation is incomplete, the result will be
-disappointing.
-Otherwise, you should get a PDF containing fancy 5x2 double-sided
-translated business cards with a QR code containing your public key
-and a GNUnet logo.
-We'll explain how to use those a bit later.
-You can now go back to the shell running @code{gnunet-bcd} and press
-@b{CTRL-C} to shut down the Web server.
-@node Be Social
-@subsection Be Social
-Next, you should print out your business card and be social.
-Find a friend, help them install GNUnet and exchange business cards with
-them. Or, if you're a desperate loner, you might try the next step with
-your own card. Still, it'll be hard to have a conversation with
-yourself later, so it would be better if you could find a friend.
-You might also want a camera attached to your computer, so
-you might need a trip to the store together.
-Before we get started, we need to tell @code{gnunet-qr} which zone
-it should import new records into.  For this, run:
-@pindex gnunet-identity
-@example
-$ gnunet-identity -s namestore -e NAME
-@end example
-where NAME is the name of the zone you want to import records
-into.  In our running example, this would be ``gnu''.
-@pindex gnunet-qr
-Henceforth, for every business card you collect, simply run:
-@example
-$ gnunet-qr
-@end example
-@noindent
-to open a window showing whatever your camera points at.
-Hold up your friend's business card and tilt it until
-the QR code is recognized. At that point, the window should
-automatically close. At that point, your friend's NICKname and their
-public key should have been automatically imported into your zone.
-Assuming both of your peers are properly integrated in the
-GNUnet network at this time, you should thus be able to
-resolve your friends names. Suppose your friend's nickname
-is "Bob". Then, type
-@pindex gnunet-gns
-@example
-$ gnunet-gns -u test.bob.gnu
-@end example
-@noindent
-to check if your friend was as good at following instructions
-as you were.
-@node Backup of Identities and Egos
-@subsection Backup of Identities and Egos
-One should always backup their files, especially in these SSD days (our
-team has suffered 3 SSD crashes over a span of 2 weeks). Backing up peer
-identity and zones is achieved by copying the following files:
-The peer identity file can be found
-in @file{~/.local/share/gnunet/private_key.ecc}
-The private keys of your egos are stored in the
-directory @file{~/.local/share/gnunet/identity/egos/}.
-They are stored in files whose filenames correspond to the zones'
-ego names.  These are probably the most important files you want
-to backup from a GNUnet installation.
-Note: All these files contain cryptographic keys and they are
-stored without any encryption.  So it is advisable to backup
-encrypted copies of them.
-@node Revocation
-@subsection Revocation
-Now, in the situation of an attacker gaining access to the private key of
-one of your egos, the attacker can create records in the respective
-GNS zone
-and publish them as if you published them.  Anyone resolving your
-domain will get these new records and when they verify they seem
-authentic because the attacker has signed them with your key.
-To address this potential security issue, you can pre-compute
-a revocation certificate corresponding to your ego.  This certificate,
-when published on the P2P network, flags your private key as invalid,
-and all further resolutions or other checks involving the key will fail.
-@pindex gnunet-revocation
-A revocation certificate is thus a useful tool when things go out of
-control, but at the same time it should be stored securely.
-Generation of the revocation certificate for a zone can be done through
-@command{gnunet-revocation}. For example, the following command (as
-unprivileged user) generates a revocation file
-@file{revocation.dat} for the zone @code{zone1}:
-@command{gnunet-revocation -f revocation.dat -R zone1}
-The above command only pre-computes a revocation certificate.  It does
-not revoke the given zone.  Pre-computing a revocation certificate
-involves computing a proof-of-work and hence may take up to 4 to 5 days
-on a modern processor.  Note that you can abort and resume the
-calculation at any time. Also, even if you did not finish the
-calculation, the resulting file will contain the signature, which is
-sufficient to complete the revocation process even without access to
-the private key.  So instead of waiting for a few days, you can just
-abort with CTRL-C, backup the revocation certificate and run the
-calculation only if your key actually was compromised. This has the
-disadvantage of revocation taking longer after the incident, but
-the advantage of saving a significant amount of energy.  So unless
-you believe that a key compromise will need a rapid response, we
-urge you to wait with generating the revocation certificate.
-Also, the calculation is deliberately expensive, to deter people from
-doing this just for fun (as the actual revocation operation is expensive
-for the network, not for the peer performing the revocation).
-@c FIXME: The Manual should give away the command using an example that is
-@c very likely to never exist.
-To avoid TL;DR ones from accidentally revocating their zones, we are not
-giving away the command, but it is uncomplicated: the actual revocation is
-performed by using the @command{-p} option of @command{gnunet-revocation}.
-@node What's Next?
-@subsection What's Next?
-This may seem not like much of an application yet, but you have
-just been one of the first to perform a decentralized secure name
-lookup (where nobody could have altered the value supplied by your
-friend) in a privacy-preserving manner (your query on the network
-and the corresponding response were always encrypted). So what
-can you really do with this? Well, to start with, you can publish your
-GnuPG fingerprint in GNS as a "CERT" record and replace the public
-web-of-trust with its complicated trust model with explicit names
-and privacy-preserving resolution. Also, you should read the next
-chapter of the tutorial and learn how to use GNS to have a
-private conversation with your friend. Finally, help us
-with the next GNUnet release for even more applications
-using this new public key infrastructure.
-@pindex gnunet-conservation-gtk
-@node First steps - Using GNUnet Conversation
-@section First steps - Using GNUnet Conversation
-First, you should launch the graphical user interface.  You can do
-this from the command-line by typing
-@example
-$ gnunet-conversation-gtk
-@end example
-@menu
-* Testing your Audio Equipment::
-* GNS Zones::
-@end menu
-@node Testing your Audio Equipment
-@subsection Testing your Audio Equipment
-First, you should use @code{gnunet-conversation-test} to check that your
-microphone and speaker are working correctly. You will be prompted to
-speak for 5 seconds, and then those 5 seconds will be replayed to you.
-The network is not involved in this test. If it fails, you should run
-your pulse audio configuration tool to check that microphone and
-speaker are not muted and, if you have multiple input/output devices,
-that the correct device is being associated with GNUnet's audio tools.
-@node GNS Zones
-@subsection GNS Zones
-@code{gnunet-conversation} uses GNS for addressing. This means that
-you need to have a GNS zone created before using it. Information
-about how to create GNS zones can be found here.
-@menu
-* Picking an Identity::
-* Calling somebody::
-@end menu
-@node Picking an Identity
-@subsubsection Picking an Identity
-To make a call with @code{gnunet-conversation}, you first
-need to choose an identity. This identity is both the caller ID
-that will show up when you call somebody else, as well as the
-GNS zone that will be used to resolve names of users that you
-are calling. Run
-@pindex gnunet-conversation
-@example
-gnunet-conversation -e zone-name
-@end example
-@noindent
-to start the command-line tool. You will see a message saying
-that your phone is now "active on line 0". You can connect
-multiple phones on different lines at the same peer. For the
-first phone, the line zero is of course a fine choice.
-Next, you should type in @command{/help} for a list of
-available commands. We will explain the important ones
-during this tutorial. First, you will need to type in
-@command{/address} to determine the address of your
-phone. The result should look something like this:
-@example
-/address
-0-PD67SGHF3E0447TU9HADIVU9OM7V4QHTOG0EBU69TFRI2LG63DR0
-@end example
-@noindent
-Here, the "0" is your phone line, and what follows
-after the hyphen is your peer's identity. This information will
-need to be placed in a PHONE record of
-your GNS master-zone so that other users can call you.
-Start @code{gnunet-namestore-gtk} now (possibly from another
-shell) and create an entry home-phone in your master zone.
-For the record type, select PHONE. You should then see the
-PHONE dialog:
-@image{images/gnunet-namestore-gtk-phone,5in,,Dialog to publish a PHONE record}
-Note: Do not choose the expiry time to be 'Never'. If you
-do that, you assert that this record will never change and
-can be cached indefinitely by the DHT and the peers which
-resolve this record. A reasonable period is 1 year.
-Enter your peer identity under Peer and leave the line
-at zero. Select the first option to make the record public.
-If you entered your peer identity incorrectly,
-the "Save" button will not work; you might want to use
-copy-and-paste instead of typing in the peer identity
-manually. Save the record.
-@node Calling somebody
-@subsubsection Calling somebody
-Now you can call a buddy. Obviously, your buddy will have to have GNUnet
-installed and must have performed the same steps. Also, you must have
-your buddy in your GNS master zone, for example by having imported
-your buddy's public key using @code{gnunet-qr}. Suppose your buddy
-is in your zone as @code{buddy.mytld} and they also created their
-phone using a label "home-phone". Then you can initiate a call using:
-@example
-/call home-phone.buddy.mytld
-@end example
-It may take some time for GNUnet to resolve the name and to establish
-a link. If your buddy has your public key in their master zone, they
-should see an incoming call with your name. If your public key is not
-in their master zone, they will just see the public key as the caller ID.
-Your buddy then can answer the call using the "/accept" command. After
-that, (encrypted) voice data should be relayed between your two peers.
-Either of you can end the call using @command{/cancel}. You can exit
-@code{gnunet-conversation} using @command{/quit}.
-@node First steps - Using the GNUnet VPN
-@section First steps - Using the GNUnet VPN
-@menu
-* VPN Preliminaries::
-* GNUnet-Exit configuration::
-* GNS configuration::
-* Accessing the service::
-* Using a Browser::
-@end menu
-@node VPN Preliminaries
-@subsection VPN Preliminaries
-To test the GNUnet VPN, we should first run a web server.
-The easiest way to do this is to just start @code{gnunet-bcd},
-which will run a webserver on port @code{8888} by default.
-Naturally, you can run some other HTTP server for our little tutorial.
-If you have not done this, you should also configure your
-Name System Service switch to use GNS. In your @code{/etc/nsswitch.conf}
-you should fine a line like this:
-@example
-hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4
-@end example
-@noindent
-The exact details may differ a bit, which is fine. Add the text
-@code{gns [NOTFOUND=return]} after @code{files}:
-@example
-hosts: files gns [NOTFOUND=return] mdns4_minimal [NOTFOUND=return] dns mdns4
-@end example
-@c TODO: outdated section, we no longer install this as part of the
-@c TODO: standard installation procedure and should point out the manual
-@c TODO: steps required to make it useful.
-@noindent
-You might want to make sure that @code{/lib/libnss_gns.so.2} exists on
-your system, it should have been created during the installation.
-If not, re-run
-@example
-$ configure --with-nssdir=/lib
-$ cd src/gns/nss; sudo make install
-@end example
-@noindent
-to install the NSS plugins in the proper location.
-@node GNUnet-Exit configuration
-@subsection GNUnet-Exit configuration
-Stop your peer (as user @code{gnunet}, run @command{gnunet-arm -e}) and
-run @command{gnunet-setup}. In @command{gnunet-setup}, make sure to
-activate the @strong{EXIT} and @strong{GNS} services in the General tab.
-Then select the Exit tab. Most of the defaults should be fine (but
-you should check against the screenshot that they have not been modified).
-In the bottom area, enter @code{bcd} under Identifier and change the
-Destination to @code{169.254.86.1:8888} (if your server runs on a port
-other than 8888, change the 8888 port accordingly).
-Now exit @command{gnunet-setup} and restart your peer
-(@command{gnunet-arm -s}).
-@node GNS configuration
-@subsection GNS configuration
-Now, using your normal user (not the @code{gnunet} system user), run
-@command{gnunet-namestore-gtk}. Add a new label www in your
-master zone. For the record type, select @code{VPN}. You should then
-see the VPN dialog:
-@image{images/gnunet-namestore-gtk-vpn,5in,,Dialog to publish a VPN record}
-Under peer, you need to supply the peer identity of your own peer. You can
-obtain the respective string by running @command{gnunet-peerinfo -sq}
-as the @code{gnunet} user. For the Identifier, you need to supply the same
-identifier that we used in the Exit setup earlier, so here supply "bcd".
-If you want others to be able to use the service, you should probably make
-the record public. For non-public services, you should use a passphrase
-instead of the string "bcd". Save the record and
-exit @command{gnunet-namestore-gtk}.
-@node Accessing the service
-@subsection Accessing the service
-You should now be able to access your webserver. Type in:
-@example
-$ wget http://www.gnu/
-@end example
-@noindent
-The request will resolve to the VPN record, telling the GNS resolver
-to route it via the GNUnet VPN. The GNS resolver will ask the
-GNUnet VPN for an IPv4 address to return to the application. The
-VPN service will use the VPN information supplied by GNS to create
-a tunnel (via GNUnet's MESH service) to the EXIT peer.
-At the EXIT, the name "bcd" and destination port (80) will be mapped
-to the specified destination IP and port. While all this is currently
-happening on just the local machine, it should also work with other
-peers --- naturally, they will need a way to access your GNS zone
-first, for example by learning your public key from a QR code on
-your business card.
-@node Using a Browser
-@subsection Using a Browser
-Sadly, modern browsers tend to bypass the Name Services Switch and
-attempt DNS resolution directly. You can either run
-a @code{gnunet-dns2gns} DNS proxy, or point the browsers to an
-HTTP proxy. When we tried it, Iceweasel did not like to connect to
-the socks proxy for @code{.gnu} TLDs, even if we disabled its
-autoblunder of changing @code{.gnu} to ".gnu.com". Still,
-using the HTTP proxy with Chrome does work.
-@node File-sharing
-@section File-sharing
-This chapter documents the GNUnet file-sharing application. The original
-file-sharing implementation for GNUnet was designed to provide
-@strong{anonymous} file-sharing. However, over time, we have also added
-support for non-anonymous file-sharing (which can provide better
-performance). Anonymous and non-anonymous file-sharing are quite
-integrated in GNUnet and, except for routing, share most of the concepts
-and implementation. There are three primary file-sharing operations:
-publishing, searching and downloading. For each of these operations,
-the user specifies an @strong{anonymity level}. If both the publisher and
-the searcher/downloader specify "no anonymity", non-anonymous
-file-sharing is used. If either user specifies some desired degree
-of anonymity, anonymous file-sharing will be used.
-After a short introduction, we will first look at the various concepts
-in GNUnet's file-sharing implementation. Then, we will discuss
-specifics as to how they impact users that publish, search or download
-files.
-@menu
-* fs-Searching::
-* fs-Downloading::
-* fs-Publishing::
-* fs-Concepts::
-* Namespace Management::
-* File-Sharing URIs::
-* GTK User Interface::
-@end menu
-@node fs-Searching
-@subsection Searching
-The command @command{gnunet-search} can be used to search
-for content on GNUnet. The format is:
-@example
-$ gnunet-search [-t TIMEOUT] KEYWORD
-@end example
-@noindent
-The @command{-t} option specifies that the query should timeout after
-approximately TIMEOUT seconds. A value of zero (``0'') is interpreted
-as @emph{no timeout}, which is the default. In this case,
-@command{gnunet-search} will never terminate (unless you press
-@command{CTRL-C}).
-If multiple words are passed as keywords, they will all be
-considered optional. Prefix keywords with a "+" to make them mandatory.
-Note that searching using
-@example
-$ gnunet-search Das Kapital
-@end example
-@noindent
-is not the same as searching for
-@example
-$ gnunet-search "Das Kapital"
-@end example
-@noindent
-as the first will match files shared under the keywords
-"Das" or "Kapital" whereas the second will match files
-shared under the keyword "Das Kapital".
-Search results are printed by @command{gnunet-search} like this:
-@c it will be better the avoid the ellipsis altogether because I don't
-@c understand the explanation below that
-@c ng0: who is ``I'' and what was the complete sentence?
-@example
-#15:
-gnunet-download -o "COPYING" gnunet://fs/chk/PGK8M...3EK130.75446
-@end example
-@noindent
-The whole line is the command you would have to enter to download
-the file. The first argument passed to @code{-o} is the suggested
-filename (you may change it to whatever you like).
-It is followed by the key for decrypting the file, the query for
-searching the file, a checksum (in hexadecimal) finally the size of
-the file in bytes.
-@node fs-Downloading
-@subsection Downloading
-In order to download a file, you need the whole line returned by
-@command{gnunet-search}.
-You can then use the tool @command{gnunet-download} to obtain the file:
-@example
-$ gnunet-download -o <FILENAME> <GNUNET-URL>
-@end example
-@noindent
-FILENAME specifies the name of the file where GNUnet is supposed
-to write the result. Existing files are overwritten. If the
-existing file contains blocks that are identical to the
-desired download, those blocks will not be downloaded again
-(automatic resume).
-If you want to download the GPL from the previous example,
-you do the following:
-@example
-$ gnunet-download -o "COPYING" gnunet://fs/chk/PGK8M...3EK130.75446
-@end example
-@noindent
-If you ever have to abort a download, you can continue it at any time by
-re-issuing @command{gnunet-download} with the same filename.
-In that case, GNUnet will @strong{not} download blocks again that are
-already present.
-GNUnet's file-encoding mechanism will ensure file integrity, even if the
-existing file was not downloaded from GNUnet in the first place.
-You may want to use the @command{-V} switch to turn on verbose
-reporting. In this case, @command{gnunet-download} will print the
-current number of bytes downloaded whenever new data was received.
-@node fs-Publishing
-@subsection Publishing
-The command @command{gnunet-publish} can be used to add content
-to the network. The basic format of the command is
-@example
-$ gnunet-publish [-n] [-k KEYWORDS]* [-m TYPE:VALUE] FILENAME
-@end example
-For example
-@example
-$ gnunet-publish -m "description:GNU License" -k gpl -k test -m "mimetype:text/plain" COPYING
-@end example
-@menu
-* Important command-line options::
-* Indexing vs. Inserting::
-@end menu
-@node Important command-line options
-@subsubsection Important command-line options
-The option @code{-k} is used to specify keywords for the file that
-should be inserted. You can supply any number of keywords,
-and each of the keywords will be sufficient to locate and
-retrieve the file. Please note that you must use the @code{-k} option
-more than once -- one for each expression you use as a keyword for
-the filename.
-The -m option is used to specify meta-data, such as descriptions.
-You can use -m multiple times. The TYPE passed must be from the
-list of meta-data types known to libextractor. You can obtain this
-list by running @command{extract -L}. Use quotes around the entire
-meta-data argument if the value contains spaces. The meta-data
-is displayed to other users when they select which files to
-download. The meta-data and the keywords are optional and
-may be inferred using @code{GNU libextractor}.
-@command{gnunet-publish} has a few additional options to handle
-namespaces and directories. Refer to the man-page for details:
-@example
-man gnunet-publish
-@end example
-@node Indexing vs. Inserting
-@subsubsection Indexing vs Inserting
-By default, GNUnet indexes a file instead of making a full copy.
-This is much more efficient, but requires the file to stay unaltered
-at the location where it was when it was indexed. If you intend to move,
-delete or alter a file, consider using the option @code{-n} which will
-force GNUnet to make a copy of the file in the database.
-Since it is much less efficient, this is strongly discouraged for large
-files. When GNUnet indexes a file (default), GNUnet does @strong{not}
-create an additional encrypted copy of the file but just computes a
-summary (or index) of the file. That summary is approximately two percent
-of the size of the original file and is stored in GNUnet's database.
-Whenever a request for a part of an indexed file reaches GNUnet,
-this part is encrypted on-demand and send out. This way, there is no
-need for an additional encrypted copy of the file to stay anywhere
-on the drive. This is different from other systems, such as Freenet,
-where each file that is put online must be in Freenet's database in
-encrypted format, doubling the space requirements if the user wants
-to preserve a directly accessible copy in plaintext.
-Thus indexing should be used for all files where the user will keep
-using this file (at the location given to gnunet-publish) and does
-not want to retrieve it back from GNUnet each time. If you want to
-remove a file that you have indexed from the local peer, use the tool
-@command{gnunet-unindex} to un-index the file.
-The option @code{-n} may be used if the user fears that the file might
-be found on their drive (assuming the computer comes under the control
-of an adversary). When used with the @code{-n} flag, the user has a
-much better chance of denying knowledge of the existence of the file,
-even if it is still (encrypted) on the drive and the adversary is
-able to crack the encryption (e.g. by guessing the keyword.
-@node fs-Concepts
-@subsection Concepts
-For better results with filesharing it is useful to understand the
-following concepts.
-In addition to anonymous routing GNUnet attempts to give users a better
-experience in searching for content. GNUnet uses cryptography to safely
-break content into smaller pieces that can be obtained from different
-sources without allowing participants to corrupt files. GNUnet makes it
-difficult for an adversary to send back bogus search results. GNUnet
-enables content providers to group related content and to establish a
-reputation. Furthermore, GNUnet allows updates to certain content to be
-made available. This section is supposed to introduce users to the
-concepts that are used to achieve these goals.
-@menu
-* Files::
-* Keywords::
-* Directories::
-* Egos and File-Sharing::
-* Namespaces::
-* Advertisements::
-* Anonymity level::
-* Content Priority::
-* Replication::
-@end menu
-@node Files
-@subsubsection Files
-A file in GNUnet is just a sequence of bytes. Any file-format is allowed
-and the maximum file size is theoretically @math{2^64 - 1} bytes, except
-that it would take an impractical amount of time to share such a file.
-GNUnet itself never interprets the contents of shared files, except when
-using GNU libextractor to obtain keywords.
-@node Keywords
-@subsubsection Keywords
-Keywords are the most simple mechanism to find files on GNUnet.
-Keywords are @strong{case-sensitive} and the search string
-must always match @strong{exactly} the keyword used by the
-person providing the file. Keywords are never transmitted in
-plaintext. The only way for an adversary to determine the keyword
-that you used to search is to guess it (which then allows the
-adversary to produce the same search request). Since providing
-keywords by hand for each shared file is tedious, GNUnet uses
-GNU libextractor to help automate this process. Starting a
-keyword search on a slow machine can take a little while since
-the keyword search involves computing a fresh RSA key to formulate the
-request.
-@node Directories
-@subsubsection Directories
-A directory in GNUnet is a list of file identifiers with meta data.
-The file identifiers provide sufficient information about the files
-to allow downloading the contents. Once a directory has been created,
-it cannot be changed since it is treated just like an ordinary file
-by the network. Small files (of a few kilobytes) can be inlined in
-the directory, so that a separate download becomes unnecessary.
-Directories are shared just like ordinary files. If you download a
-directory with @command{gnunet-download}, you can use
-@command{gnunet-directory} to list its contents. The canonical
-extension for GNUnet directories when stored as files in your
-local file-system is ".gnd". The contents of a directory are URIs and
-meta data.
-The URIs contain all the information required by
-@command{gnunet-download} to retrieve the file. The meta data
-typically includes the mime-type, description, a filename and
-other meta information, and possibly even the full original file
-(if it was small).
-@node Egos and File-Sharing
-@subsubsection Egos and File-Sharing
-When sharing files, it is sometimes desirable to build a reputation as
-a source for quality information.  With egos, publishers can
-(cryptographically) sign files, thereby demonstrating that various
-files were published by the same entity.  An ego thus allows users to
-link different publication events, thereby deliberately reducing
-anonymity to pseudonymity.
-Egos used in GNUnet's file-sharing for such pseudonymous publishing
-also correspond to the egos used to identify and sign zones in the
-GNU Name System.  However, if the same ego is used for file-sharing
-and for a GNS zone, this will weaken the privacy assurances provided
-by the anonymous file-sharing protocol.
-Note that an ego is NOT bound to a GNUnet peer. There can be multiple
-egos for a single user, and users could (theoretically) share
-the private keys of an ego by copying the respective private keys.
-@node Namespaces
-@subsubsection Namespaces
-A namespace is a set of files that were signed by the same ego.
-Today, namespaces are implemented independently of GNS zones, but
-in the future we plan to merge the two such that a GNS zone can
-basically contain files using a file-sharing specific record type.
-Files (or directories) that have been signed and placed into a
-namespace can be updated. Updates are identified as authentic if the
-same secret key was used to sign the update.
-@node Advertisements
-@subsubsection Advertisements
-Advertisements are used to notify other users about the existence of a
-namespace. Advertisements are propagated using the normal keyword
-search.  When an advertisement is received (in response to a search),
-the namespace is added to the list of namespaces available in the
-namespace-search dialogs of gnunet-fs-gtk and printed by
-@code{gnunet-identity}. Whenever a namespace is created, an
-appropriate advertisement can be generated.  The default keyword for
-the advertising of namespaces is "namespace".
-@node Anonymity level
-@subsubsection Anonymity level
-The anonymity level determines how hard it should be for an adversary to
-determine the identity of the publisher or the searcher/downloader. An
-anonymity level of zero means that anonymity is not required. The default
-anonymity level of "1" means that anonymous routing is desired, but no
-particular amount of cover traffic is necessary. A powerful adversary
-might thus still be able to deduce the origin of the traffic using
-traffic analysis. Specifying higher anonymity levels increases the
-amount of cover traffic required.
-The specific numeric value (for anonymity levels above 1) is simple:
-Given an anonymity level L (above 1), each request FS makes on your
-behalf must be hidden in L-1 equivalent requests of cover traffic
-(traffic your peer routes for others) in the same time-period.  The
-time-period is twice the average delay by which GNUnet artificially
-delays traffic.
-While higher anonymity levels may offer better privacy, they can also
-significantly hurt performance.
-@node Content Priority
-@subsubsection Content Priority
-Depending on the peer's configuration, GNUnet peers migrate content
-between peers. Content in this sense are individual blocks of a file,
-not necessarily entire files. When peers run out of space (due to
-local publishing operations or due to migration of content from other
-peers), blocks sometimes need to be discarded. GNUnet first always
-discards expired blocks (typically, blocks are published with an
-expiration of about two years in the future; this is another option).
-If there is still not enough space, GNUnet discards the blocks with the
-lowest priority. The priority of a block is decided by its popularity
-(in terms of requests from peers we trust) and, in case of blocks
-published locally, the base-priority that was specified by the user
-when the block was published initially.
-@node Replication
-@subsubsection Replication
-When peers migrate content to other systems, the replication level
-of a block is used to decide which blocks need to be migrated most
-urgently. GNUnet will always push the block with the highest
-replication level into the network, and then decrement the replication
-level by one. If all blocks reach replication level zero, the
-selection is simply random.
-@node Namespace Management
-@subsection Namespace Management
-The @code{gnunet-identity} tool can be used to create egos.
-By default, @code{gnunet-identity --display} simply
-lists all locally available egos.
-@menu
-* Creating Egos::
-* Deleting Egos::
-@end menu
-@node Creating Egos
-@subsubsection Creating Egos
-With the @command{--create=NICK} option it can also be used to create a new
-ego. An ego is the virtual identity of the entity in control of a
-namespace or GNS zone. Anyone can create any number of egos.  The
-provided NICK name automatically corresponds to a GNU Name System
-domain name.  Thus, henceforth name resolution for any name ending in
-``.NICK'' will use the NICK's zone.  You should avoid using NICKs that
-collide with well-known DNS names.
-Currently, the IDENTITY subsystem supports two types of identity keys:
-ECDSA and EdDSA. By default, ECDSA identities are creates with ECDSA keys.
-In order to create an identity with EdDSA keys, you can use the
-@command{--eddsa} flag.
-@node Deleting Egos
-@subsubsection Deleting Egos
-With the @command{-D NICK} option egos can be deleted.  Once the ego
-has been deleted it is impossible to add content to the corresponding
-namespace or zone. However, the existing GNS zone data is currently
-not dropped. This may change in the future.
-Deleting the pseudonym does not make the namespace or any content in
-it unavailable.
-@node File-Sharing URIs
-@subsection File-Sharing URIs
-GNUnet (currently) uses four different types of URIs for
-file-sharing. They all begin with "gnunet://fs/".
-This section describes the four different URI types in detail.
-For FS URIs empty KEYWORDs are not allowed. Quotes are allowed to
-denote whitespace between words. Keywords must contain a balanced
-number of double quotes. Doubles quotes can not be used in the actual
-keywords. This means that the string '""foo bar""' will be turned
-into two OR-ed keywords 'foo' and 'bar', not into '"foo bar"'.
-@menu
-* Encoding of hash values in URIs::
-* Content Hash Key (chk)::
-* Location identifiers (loc)::
-* Keyword queries (ksk)::
-* Namespace content (sks)::
-@end menu
-@node Encoding of hash values in URIs
-@subsubsection Encoding of hash values in URIs
-Most URIs include some hash values. Hashes are encoded using
-base32hex (RFC 2938).
-@cindex chk-uri
-@node Content Hash Key (chk)
-@subsubsection Content Hash Key (chk)
-A chk-URI is used to (uniquely) identify a file or directory
-and to allow peers to download the file. Files are stored in
-GNUnet as a tree of encrypted blocks.
-The chk-URI thus contains the information to download and decrypt
-those blocks. A chk-URI has the format
-"gnunet://fs/chk/KEYHASH.QUERYHASH.SIZE". Here, "SIZE"
-is the size of the file (which allows a peer to determine the
-shape of the tree), KEYHASH is the key used to decrypt the file
-(also the hash of the plaintext of the top block) and QUERYHASH
-is the query used to request the top-level block (also the hash
-of the encrypted block).
-@cindex loc-uri
-@node Location identifiers (loc)
-@subsubsection Location identifiers (loc)
-For non-anonymous file-sharing, loc-URIs are used to specify which
-peer is offering the data (in addition to specifying all of the
-data from a chk-URI). Location identifiers include a digital
-signature of the peer to affirm that the peer is truly the
-origin of the data. The format is
-"gnunet://fs/loc/KEYHASH.QUERYHASH.SIZE.PEER.SIG.EXPTIME".
-Here, "PEER" is the public key of the peer (in GNUnet format in
-base32hex), SIG is the RSA signature (in GNUnet format in
-base32hex) and EXPTIME specifies when the signature expires
-(in milliseconds after 1970).
-@cindex ksk-uri
-@node Keyword queries (ksk)
-@subsubsection Keyword queries (ksk)
-A keyword-URI is used to specify that the desired operation
-is the search using a particular keyword. The format is simply
-"gnunet://fs/ksk/KEYWORD". Non-ASCII characters can be specified
-using the typical URI-encoding (using hex values) from HTTP.
-"+" can be used to specify multiple keywords (which are then
-logically "OR"-ed in the search, results matching both keywords
-are given a higher rank): "gnunet://fs/ksk/KEYWORD1+KEYWORD2".
-ksk-URIs must not begin or end with the plus ('+') character.
-Furthermore they must not contain '++'.
-@cindex sks-uri
-@node Namespace content (sks)
-@subsubsection Namespace content (sks)
-@b{Please note that the text in this subsection is outdated and needs}
-@b{to be rewritten for version 0.10!}
-@b{This especially concerns the terminology of Pseudonym/Ego/Identity.}
-Namespaces are sets of files that have been approved by some (usually
-pseudonymous) user --- typically by that user publishing all of the
-files together. A file can be in many namespaces. A file is in a
-namespace if the owner of the ego (aka the namespace's private key)
-signs the CHK of the file cryptographically. An SKS-URI is used to
-search a namespace. The result is a block containing meta data,
-the CHK and the namespace owner's signature. The format of a sks-URI
-is "gnunet://fs/sks/NAMESPACE/IDENTIFIER". Here, "NAMESPACE"
-is the public key for the namespace. "IDENTIFIER" is a freely
-chosen keyword (or password!). A commonly used identifier is
-"root" which by convention refers to some kind of index or other
-entry point into the namespace.
-@node GTK User Interface
-@subsection GTK User Interface
-This chapter describes first steps for file-sharing with GNUnet.
-To start, you should launch @command{gnunet-fs-gtk}.
-As we want to be sure that the network contains the data that we are
-looking for for testing, we need to begin by publishing a file.
-@menu
-* gtk-Publishing::
-* gtk-Searching::
-* gtk-Downloading::
-@end menu
-@node gtk-Publishing
-@subsubsection Publishing
-To publish a file, select "File Sharing" in the menu bar just below the
-"Statistics" icon, and then select "Publish" from the menu.
-Afterwards, the following publishing dialog will appear:
-@image{images/gnunet-gtk-0-10-fs-publish,5in,,The gnunet-fs-gtk publishing dialog}
-In this dialog, select the "Add File" button. This will open a
-file selection dialog:
-@image{images/gnunet-gtk-0-10-fs-publish-select,5in,,Dialog to select the file to publish (looks may differ for other Gtk+ versions)}
-Now, you should select a file from your computer to be published on
-GNUnet. To see more of GNUnet's features later, you should pick a
-PNG or JPEG file this time. You can leave all of the other options
-in the dialog unchanged. Confirm your selection by pressing the "OK"
-button in the bottom right corner. Now, you will briefly see a
-"Messages..." dialog pop up, but most likely it will be too short for
-you to really read anything. That dialog is showing you progress
-information as GNUnet takes a first look at the selected file(s).
-For a normal image, this is virtually instant, but if you later
-import a larger directory you might be interested in the progress dialog
-and potential errors that might be encountered during processing.
-After the progress dialog automatically disappears, your file
-should now appear in the publishing dialog:
-@image{images/gnunet-gtk-0-10-fs-publish-with-file,5in,,Publishing dialog with file added}
-Now, select the file (by clicking on the file name) and then click
-the "Edit" button. This will open the editing dialog:
-@image{images/gnunet-gtk-0-10-fs-publish-editing,5in,,Editing meta data of a file to be published}
-In this dialog, you can see many details about your file. In the
-top left area, you can see meta data extracted about the file,
-such as the original filename, the mimetype and the size of the image.
-In the top right, you should see a preview for the image
-(if GNU libextractor was installed correctly with the
-respective plugins). Note that if you do not see a preview, this
-is not a disaster, but you might still want to install more of
-GNU libextractor in the future. In the bottom left, the dialog contains
-a list of keywords. These are the keywords under which the file will be
-made available. The initial list will be based on the extracted meta data.
-Additional publishing options are in the right bottom corner. We will
-now add an additional keyword to the list of keywords. This is done by
-entering the keyword above the keyword list between the label "Keyword"
-and the "Add keyword" button. Enter "test" and select "Add keyword".
-Note that the keyword will appear at the bottom of the existing keyword
-list, so you might have to scroll down to see it. Afterwards, push the
-"OK" button at the bottom right of the dialog.
-You should now be back at the "Publish content on GNUnet" dialog. Select
-"Execute" in the bottom right to close the dialog and publish your file
-on GNUnet! Afterwards, you should see the main dialog with a new area
-showing the list of published files (or ongoing publishing operations
-with progress indicators).
-@node gtk-Searching
-@subsubsection Searching
-Below the menu bar, there are four entry widges labeled "Namespace",
-"Keywords", "Anonymity" and "Mime-type" (from left to right). These
-widgets are used to control searching for files in GNUnet. Between the
-"Keywords" and "Anonymity" widgets, there is also a big "Search" button,
-which is used to initiate the search. We will ignore the "Namespace",
-"Anonymity" and "Mime-type" options in this tutorial, please leave them
-empty. Instead, simply enter "test" under "Keywords" and press "Search".
-Afterwards, you should immediately see a new tab labeled after your
-search term, followed by the (current) number of search
-results --- "(15)" in our screenshot. Note that your results may
-vary depending on what other users may have shared and how your
-peer is connected.
-You can now select one of the search results. Once you do this,
-additional information about the result should be displayed on the
-right. If available, a preview image should appear on the top right.
-Meta data describing the file will be listed at the bottom right.
-Once a file is selected, at the bottom of the search result list
-a little area for downloading appears.
-@node gtk-Downloading
-@subsubsection Downloading
-In the downloading area, you can select the target directory (default is
-"Downloads") and specify the desired filename (by default the filename it
-taken from the meta data of the published file). Additionally, you can
-specify if the download should be anonymous and (for directories) if
-the download should be recursive. In most cases, you can simply start
-the download with the "Download!" button.
-Once you selected download, the progress of the download will be
-displayed with the search result. You may need to resize the result
-list or scroll to the right. The "Status" column shows the current
-status of the download, and "Progress" how much has been completed.
-When you close the search tab (by clicking on the "X" button next to
-the "test" label), ongoing and completed downloads are not aborted
-but moved to a special "*" tab.
-You can remove completed downloads from the "*" tab by clicking the
-cleanup button next to the "*". You can also abort downloads by right
-clicking on the respective download and selecting "Abort download"
-from the menu.
-That's it, you now know the basics for file-sharing with GNUnet!
-@node The GNU Name System
-@section The GNU Name System
-The GNU Name System (GNS) is secure and decentralized naming system.
-It allows its users to register names as @dfn{top-level domains} (TLDs) and
-resolve other namespaces within their TLDs.
-GNS is designed to provide:
-@itemize @bullet
-@item Censorship resistance
-@item Query privacy
-@item Secure name resolution
-@item Compatibility with DNS
-@end itemize
-For the initial configuration and population of your
-GNS installation, please follow the GNS setup instructions.
-The remainder of this chapter will provide some background on GNS
-and then describe how to use GNS in more detail.
-Unlike DNS, GNS does not rely on central root zones or authorities.
-Instead any user administers their own root and can can create arbitrary
-name value mappings. Furthermore users can delegate resolution to other
-users' zones just like DNS NS records do. Zones are uniquely identified
-via public keys and resource records are signed using the corresponding
-public key. Delegation to another user's zone is done using special PKEY
-records and petnames. A petname is a name that can be freely chosen by
-the user. This results in non-unique name-value mappings as
-@code{@uref{http://www.bob.gnu/, www.bob.gnu}} to one user might be
-@code{@uref{http://www.friend.gnu/, www.friend.gnu}} for someone else.
-@menu
-* Creating a Zone::
-* Maintaining your own Zones::
-* Obtaining your Zone Key::
-* Adding Links to Other Zones::
-* Using Public Keys as Top Level Domains::
-* Resource Records in GNS::
-* Synchronizing with legacy DNS::
-* Migrating an existing DNS zone into GNS::
-@end menu
-@node Creating a Zone
-@subsection Creating a Zone
-To use GNS, you probably should create at least one zone of your own.
-You can create any number of zones using the gnunet-identity tool
-using:
-@example
-$ gnunet-identity --create="myzone"
-@end example
-Henceforth, on your system you control the TLD ``myzone''.
-All of your zones can be listed (displayed) using the
-@command{gnunet-identity} command line tool as well:
-@example
-$ gnunet-identity --display
-@end example
-@node Maintaining your own Zones
-@subsection Maintaining your own Zones
-@noindent
-Now you can add (or edit, or remove) records in your GNS zone using the
-@command{gnunet-namestore-gtk} GUI or using the @command{gnunet-namestore}
-command-line tool.
-In either case, your records will be stored in an SQL database under
-control of the @command{gnunet-service-namestore}.
-Note that if multiple users use one peer, the namestore database will
-include the combined records of all users.
-However, users will not be able to see each other's records
-if they are marked as private.
-To provide a short example for editing your own zone, suppose you
-have your own web server with the IP @code{1.2.3.4}. Then you can put an
-@code{A} record (@code{A} records in DNS are for IPv4 IP addresses)
-into your local zone ``myzone'' using the command:
-@example
-$ gnunet-namestore -z myzone -a -n www -t A -V 1.2.3.4 -e never
-@end example
-@noindent
-Afterwards, you will be able to access your webpage under "www.myzone"
-(assuming your webserver does not use virtual hosting, if it does,
-please read up on setting up the GNS proxy).
-Similar commands will work for other types of DNS and GNS records,
-the syntax largely depending on the type of the record.
-Naturally, most users may find editing the zones using the
-@command{gnunet-namestore-gtk} GUI to be easier.
-@node Obtaining your Zone Key
-@subsection Obtaining your Zone Key
-Each zone in GNS has a public-private key. Usually, gnunet-namestore and
-gnunet-setup will access your private key as necessary, so you do not
-have to worry about those. What is important is your public key
-(or rather, the hash of your public key), as you will likely want to
-give it to others so that they can securely link to you.
-You can usually get the hash of your public key using
-@example
-$ gnunet-identity -d $options | grep myzone | awk '@{print $3@}'
-@end example
-@noindent
-For example, the output might be something like:
-@example
-DC3SEECJORPHQNVRH965A6N74B1M37S721IG4RBQ15PJLLPJKUE0
-@end example
-@noindent
-Alternatively, you can obtain a QR code with your zone key AND your
-pseudonym from gnunet-namestore-gtk. The QR code is displayed in the
-main window and can be stored to disk using the ``Save as'' button
-next to the image.
-@node Adding Links to Other Zones
-@subsection Adding Links to Other Zones
-A central operation in GNS is the ability to securely delegate to
-other zones. Basically, by adding a delegation you make all of the
-names from the other zone available to yourself. This section
-describes how to create delegations.
-Suppose you have a friend who you call 'bob' who also uses GNS.
-You can then delegate resolution of names to Bob's zone by adding
-a PKEY record to their local zone:
-@example
-$ gnunet-namestore -a -n bob --type PKEY -V XXXX -e never -Z myzone
-@end example
-@noindent
-Note that ``XXXX'' in the command above must be replaced with the hash
-of Bob's public key (the output your friend obtained using the
-@command{gnunet-identity} command from the previous section and told
-you, for example by giving you a business card containing this
-information as a QR code).
-Assuming Bob has an ``A'' record for their website under the name of
-``www'' in his zone, you can then access Bob's website under
-``www.bob.myzone'' --- as well as any (public) GNS record that Bob has
-in their zone by replacing www with the respective name of the
-record in Bob's zone.
-@c themselves? themself?
-Furthermore, if Bob has themselves a (public) delegation to Carol's
-zone under "carol", you can access Carol's records under
-``NAME.carol.bob.myzone'' (where ``NAME'' is the name of Carol's
-record you want to access).
-@node Using Public Keys as Top Level Domains
-@subsection Using Public Keys as Top Level Domains
-GNS also assumes responsibility for any name that uses in a
-well-formed public key for the TLD.  Names ending this way are then
-resolved by querying the respective zone. Such public key TLDs are
-expected to be used under rare circumstances where globally unique
-names are required, and for integration with legacy systems.
-@node Resource Records in GNS
-@subsection Resource Records in GNS
-GNS supports the majority of the DNS records as defined in
-@uref{http://www.ietf.org/rfc/rfc1035.txt, RFC 1035}. Additionally,
-GNS defines some new record types the are unique to the GNS system.
-For example, GNS-specific resource records are used to give petnames
-for zone delegation, revoke zone keys and provide some compatibility
-features.
-For some DNS records, GNS does extended processing to increase their
-usefulness in GNS. In particular, GNS introduces special names
-referred to as "zone relative names". Zone relative names are allowed
-in some resource record types (for example, in NS and CNAME records)
-and can also be used in links on webpages. Zone relative names end
-in ".+" which indicates that the name needs to be resolved relative
-to the current authoritative zone. The extended processing of those
-names will expand the ".+" with the correct delegation chain to the
-authoritative zone (replacing ".+" with the name of the location
-where the name was encountered) and hence generate a
-valid GNS name.
-The GNS currently supports the record types as defined in
-@uref{https://git.gnunet.org/gana.git/tree/gnu-name-system-record-types/registry.rec, GANA}.
-In addition, GNS supports DNS record types, such as A, AAAA or TXT.
-For a complete description of the records, please refer to the specification
-at @uref{https://lsd.gnunet.org/lsd0001, LSD0001}.
-In the following, we discuss GNS records with specific behaviour or special
-handling of DNS records.
-@menu
-* NICK::
-* PKEY::
-* BOX::
-* LEHO::
-* VPN::
-* REDIRECT::
-* GNS2DNS::
-* TOMBSTONE::
-* SOA SRV PTR and MX::
-@end menu
-@node NICK
-@subsubsection NICK
-A NICK record is used to give a zone a name. With a NICK record, you
-can essentially specify how you would like to be called. GNS expects
-this record under the empty label ``@@'' in the zone's database
-(NAMESTORE); however, it will then automatically be copied into each
-record set, so that clients never need to do a separate lookup to
-discover the NICK record.  Also, users do not usually have to worry
-about setting the NICK record: it is automatically set to the local
-name of the TLD.
-@b{Example}@
-@example
-Name: @@; RRType: NICK; Value: bob
-@end example
-@noindent
-This record in Bob's zone will tell other users that this zone wants
-to be referred to as 'bob'. Note that nobody is obliged to call Bob's
-zone 'bob' in their own zones. It can be seen as a
-recommendation ("Please call this zone 'bob'").
-@node PKEY
-@subsubsection PKEY
-PKEY records are used to add delegation to other users' zones and
-give those zones a petname.
-@b{Example}@
-Let Bob's zone be identified by the hash "ABC012". Bob is your friend
-so you want to give them the petname "friend". Then you add the
-following record to your zone:
-@example
-Name: friend; RRType: PKEY; Value: ABC012;
-@end example
-@noindent
-This will allow you to resolve records in bob's zone
-under "*.friend.gnu".
-@node BOX
-@subsubsection BOX
-BOX records are there to integrate information from TLSA or
-SRV records under the main label. In DNS, TLSA and SRV records
-use special names of the form @code{_port._proto.(label.)*tld} to
-indicate the port number and protocol (like TCP or UDP) for which
-the TLSA or SRV record is valid. This causes various problems, and
-is elegantly solved in GNS by integrating the protocol and port
-numbers together with the respective value into a "BOX" record.
-Note that in the GUI, you do not get to edit BOX records directly
-right now --- the GUI will provide the illusion of directly
-editing the TLSA and SRV records, even though they internally
-are BOXed up.
-@node LEHO
-@subsubsection LEHO
-The LEgacy HOstname of a server. Some webservers expect a specific
-hostname to provide a service (virtual hosting). Also SSL
-certificates usually contain DNS names. To provide the expected
-legacy DNS name for a server, the LEHO record can be used.
-To mitigate the just mentioned issues the GNS proxy has to be used.
-The GNS proxy will use the LEHO information to apply the necessary
-transformations.
-@node VPN
-@subsubsection VPN
-GNS allows easy access to services provided by the GNUnet Virtual Public
-Network. When the GNS resolver encounters a VPN record it will contact
-the VPN service to try and allocate an IPv4/v6 address (if the queries
-record type is an IP address) that can be used to contact the service.
-@b{Example}@
-I want to provide access to the VPN service "web.gnu." on port 80 on peer
-ABC012:@
-Name: www; RRType: VPN; Value: 80 ABC012 web.gnu.
-The peer ABC012 is configured to provide an exit point for the service
-"web.gnu." on port 80 to it's server running locally on port 8080 by
-having the following lines in the @file{gnunet.conf} configuration file:
-@example
-[web.gnunet.]
-TCP_REDIRECTS = 80:localhost4:8080
-@end example
-@node REDIRECT
-@subsubsection REDIRECT
-As specified in LSD0001 whenever a REDIRECT is encountered the query
-needs to be restarted with the specified name. A REDIRECT
-can either be:
-@itemize @bullet
-@item A zone relative name,
-@item A zkey name or
-@item A DNS name (in which case resolution will continue outside
-of GNS with the systems DNS resolver)
-@end itemize
-@node GNS2DNS
-@subsubsection GNS2DNS
-GNS can delegate authority to a legacy DNS zone. For this, the
-name of the DNS nameserver and the name of the DNS zone are
-specified in a GNS2DNS record.
-@b{Example}
-@example
-Name: pet; RRType: GNS2DNS; Value: gnunet.org@@a.ns.joker.com
-@end example
-@noindent
-Any query to @code{pet.gnu} will then be delegated to the DNS server at
-@code{a.ns.joker.com}. For example,
-@code{@uref{http://www.pet.gnu/, www.pet.gnu}} will result in a DNS query
-for @code{@uref{http://www.gnunet.org/, www.gnunet.org}} to the server
-at @code{a.ns.joker.com}. Delegation to DNS via NS records in GNS can
-be useful if you do not want to start resolution in the DNS root zone
-(due to issues such as censorship or availability).
-Note that you would typically want to use a relative name for the
-nameserver, like so:
-@example
-Name: pet; RRType: GNS2DNS; Value: gnunet.org@@ns-joker.+@
-Name: ns-joker; RRType: A; Value: 184.172.157.218
-@end example
-@noindent
-This way, you can avoid involving the DNS hierarchy in the resolution of
-@code{a.ns.joker.com}. In the example above, the problem may not be
-obvious as the nameserver for "gnunet.org" is in the ".com" zone.
-However, imagine the nameserver was "ns.gnunet.org". In this case,
-delegating to "ns.gnunet.org" would mean that despite using GNS,
-censorship in the DNS ".org" zone would still be effective.
-@node TOMBSTONE
-@subsubsection TOMBSTONE
-The GNUnet GNS implementation uses the TOMBSTONE record to ensure
-ciphertext indistinguishability for published records.
-It must be ensured that when relative expiration times are decreased, the
-expiration time of the next record block MUST be after the last published block.
-A similar issue arises if the record set under a label is deleted and reused
-later.
-The creation and maintenance of the TOMBSTONE record is done automatically.
-You do not need to mind it yourself and can safely ignore any TOMBSTONE
-blocks you may see when investigating your zone(s).
-TOMBSTONE records are always private and will never be published.
-@node SOA SRV PTR and MX
-@subsubsection SOA SRV PTR and MX
-The domain names in those records can, again, be either
-@itemize @bullet
-@item A zone relative name,
-@item A zkey name or
-@item A DNS name
-@end itemize
-The resolver will expand the zone relative name if possible.
-Note that when using MX records within GNS, the target mail
-server might still refuse to accept e-mails to the resulting
-domain as the name might not match. GNS-enabled mail clients
-should use the ZKEY zone as the destination hostname and
-GNS-enabled mail servers should be configured to accept
-e-mails to the ZKEY-zones of all local users.
-To add a SOA record via the gnunet-namestore command line
-tool use the following syntax for the value option. Choose
-the other options according to your preference, however in
-this example we will use a relative expiry, add the record
-under the label @ and add the records to the zone bar
-which already exists:
-@example
-$ gnunet-namestore -a -n @ -t SOA -z bar -e 3600s -V \
->    "rname=$PRIMARY_NS \
->    mname=$CONTACT_MAIL \
->    $SERIAL,$REFRESH,$RETRY,$EXPIRY,$MINIMUM_TTL"
-@end example
-The above command filled in with values looks like this:
-@example
-$ gnunet-namestore -a -n @ -t SOA -z bar -e 3600s -V \
->    "rname=ns1.bar \
->    mname=root.bar \
->    2019081701,3600,1800,86400,7200"
-@end example
-MX records use a similar syntax which is outlined in the
-example below. $SERVER is a domain name as mentioned above.
-@example
-$ gnunet-namestore -a -n mail -t MX -z bar -e 3600s -V \
->    "$PRIORITY,$SERVER"
-@end example
-With the values substituted this is an example of a working
-command:
-@example
-$ gnunet-namestore -a -n mail -t MX -z bar -e 3600s -V \
->    "10,mail.bar"
-@end example
-@node Synchronizing with legacy DNS
-@subsection Synchronizing with legacy DNS
-If you want to support GNS but the master database for a zone
-is only available and maintained in DNS, GNUnet includes the
-@command{gnunet-zoneimport} tool to monitor a DNS zone and
-automatically import records into GNS.  Today, the tool does
-not yet support DNS AF(X)R, as we initially used it on the
-``.fr'' zone which does not allow us to perform a DNS zone
-transfer.  Instead, @command{gnunet-zoneimport} reads a list
-of DNS domain names from @code{stdin}, issues DNS queries for
-each, converts the obtained records (if possible) and stores
-the result in the namestore.
-@image{images/gns,6in,, picture of DNS-GNS data flow}
-The zonemaster service then takes the records from the namestore,
-publishes them into the DHT which makes the result available to the
-GNS resolver.  In the GNS configuration, non-local zones can be
-configured to be intercepted by specifying ``.tld = PUBLICKEY'' in the
-configuration file in the ``[gns]'' section.
-Note that the namestore by default also populates the namecache.
-This pre-population is cryptographically expensive. Thus, on
-systems that only serve to import a large (millions of records)
-DNS zone and that do not have a local gns service in use, it
-is thus advisable to disable the namecache by setting the
-option ``DISABLE'' to ``YES'' in section ``[namecache]''.
-@node Migrating an existing DNS zone into GNS
-@subsection Migrating an existing DNS zone into GNS
-Ascension is a tool to migrate existing DNS zones into GNS.
-@xref{Migrating existing DNS zones into GNS}, for installation instructions and
-further information about Ascension.
-Compared to the gnunet-zoneimport tool it strictly uses AXFR or IXFR depending
-on whether or not there exists a SOA record for the zone. If that is the case it
-will take the serial as a reference point and request the zone. The server will
-either answer the IXFR request with a correct incremental zone or with the
-entire zone, which depends on the server configuration.
-After installing the tool according to the README file you have the following
-options:
-@example
-Ascension
-Usage:
-    ascension <domain> [-d] [-p] [-s] [--minimum-ttl=<ttl>] \
-        [--dry-run]
-    ascension <domain> <port> [-d] [-p] [-s] \
-        [--minimum-ttl=<ttl>] [--dry-run]
-    ascension <domain> -n <transferns> [-d] [-p] \
-        [-s] [--minimum-ttl=<ttl>] [--dry-run]
-    ascension <domain> -n <transferns> <port> [-d] \
-        [-p] [-s] [--minimum-ttl=<ttl>] [--dry-run]
-    ascension -p | --public
-    ascension -d | --debug
-    ascension -s | --standalone
-    ascension -h | --help
-    ascension -v | --version
-Options:
-    <domain>              Domain to migrate
-    <port>                Port for zone transfer
-    <transferns>          DNS Server that does the zone transfer
-    --minimum-ttl=<ttl>   Minimum TTL for records to migrate \
-        [default: 3600]
-    --dry-run             Only try if a zone transfer is allowed
-    -p --public           Make records public on the DHT
-    -s --standalone       Run ascension once
-    -d --debug            Enable debugging
-    -h --help         Show this screen.
-    -v --version      Show version.
-@end example
-Before you can migrate any zone though, you need to start a local GNUnet peer:
-@example
-$ gnunet-arm -s
-@end example
-To migrate the Syrian top level domain - one of the few top level domains that
-support zone transfers - into GNS use the following command:
-@example
-$ ascension sy. -n ns1.tld.sy. -p
-@end example
-The -p flag will tell GNS to put these records on the DHT so that other users
-may resolve these records by using the public key of the zone.
-Once the zone is migrated, Ascension will output a message telling you, that it
-will refresh the zone after the time has elapsed.  You can resolve the names in
-the zone directly using GNS or if you want to use it with your browser, check
-out the GNS manual section. @ref{Configuring the GNU Name System}. To resolve
-the records from another system you need the respective zones PKEY. To get the
-zones public key, you can run the following command:
-@example
-$ gnunet-identity -dqe sy
-@end example
-Where "sy" is the name of the zone you want to migrate.
-You can share the PKEY of the zone with your friends. They can then resolve
-records in the zone by doing a lookup replacing the zone label with your PKEY:
-@example
-$ gnunet-gns -t SOA -u "$PKEY"
-@end example
-The program will continue to run as a daemon and update once the refresh time
-specified in the zones SOA record has elapsed.
-DNSCurve style records are supported in the latest release and they are added
-as a PKEY record to be referred to the respective GNS public key. Key
-distribution is still a problem but provided someone else has a public key
-under a given label it can be looked up.
-There is an unofficial Debian package called python3-ascension that adds a
-system user ascension and runs a GNUnet peer in the background.
-Ascension-bind is also an unofficial Debian package that on installation checks
-for running DNS zones and whether or not they are transferable using DNS zone
-transfer (AXFR). It asks the administrator which zones to migrate into GNS and
-installs a systemd unit file to keep the zone up to date.  If you want to
-migrate different zones you might want to check the unit file from the package
-as a guide.
-@node reclaimID Identity Provider
-@section reclaimID Identity Provider
-The re:claimID Identity Provider (IdP) is a decentralized IdP service.
-It allows its users to manage and authorize third parties to access
-their identity attributes such as email or shipping addresses.
-It basically mimics the concepts of centralized IdPs, such as those
-offered by Google or Facebook.
-Like other IdPs, reclaimID features an (optional) OpenID Connect
-1.0-compliant protocol layer that can be used for websites to
-integrate reclaimID as an Identity Provider with little effort.
-@menu
-* Managing Attributes::
-* Managing Credentials::
-* Sharing Attributes with Third Parties::
-* Revoking Authorizations of Third Parties::
-* OpenID Connect::
-* Providing Third Party Attestation::
-@end menu
-@node Managing Attributes
-@subsection Managing Attributes
-Before adding attributes to an identity, you must first create an ego:
-@example
-$ gnunet-identity --create="user"
-@end example
-Henceforth, you can manage a new user profile of the user ``user''.
-To add an email address to your user profile, simply use the @command{gnunet-reclaim} command line tool::
-@example
-$ gnunet-reclaim -e "user" -a "email" -V "username@@example.gnunet"
-@end example
-All of your attributes can be listed using the @command{gnunet-reclaim}
-command line tool as well:
-@example
-$ gnunet-reclaim -e "user" -D
-@end example
-Currently, and by default, attribute values are interpreted as plain text.
-In the future there might be more value types such as X.509 certificate credentials.
-@node Managing Credentials
-@subsection Managing Credentials
-Attribute values may reference a claim in a third party attested credential.
-Such a credential can have a variety of formats such as JSON-Web-Tokens or
-X.509 certificates.
-Currently, reclaimID only supports JSON-Web-Token credentials.
-To add a credential to your user profile, invoke the @command{gnunet-reclaim} command line tool as follows:
-@example
-$ gnunet-reclaim -e "user"\
-                 --credential-name="email"\
-                 --credential-type="JWT"\
-                 --value="ey..."
-@end example
-All of your credentials can be listed using the @command{gnunet-reclaim}
-command line tool as well:
-@example
-$ gnunet-reclaim -e "user" --credentials
-@end example
-In order to add an attribe backed by a credential, specify the attribute
-value as the claim name in the credential to reference along with the credential
-ID:
-@example
-$ gnunet-reclaim -e "user"\
-                 --add="email"\
-                 --value="verified_email"\
-                 --credential-id="<CREDENTIAL_ID>"
-@end example
-@node Sharing Attributes with Third Parties
-@subsection Sharing Attributes with Third Parties
-If you want to allow a third party such as a website or friend to access to your attributes (or a subset thereof) execute:
-@example
-$ TICKET=$(gnunet-reclaim -e "user"\
-                          -r "$RP_KEY"\
-                          -i "attribute1,attribute2,...")
-@end example
-The command will return a "ticket" string.
-You must give $TICKET to the requesting third party.
-$RP_KEY is the public key of the third party and "attribute1,attribute2,..." is a comma-separated list of attribute names, such as "email,name,...", that you want to share.
-The third party may retrieve the key in string format for use in the above
-call using "gnunet-identity":
-@example
-$ RP_KEY=$(gnunet-identity -d | grep "relyingparty" | awk '@{print $3@}')
-@end example
-The third party can then retrieve your shared identity attributes using:
-@example
-$ gnunet-reclaim -e "relyingparty" -C "ticket"
-@end example
-Where "relyingparty" is the name for the identity behind $RP_KEY that the
-requesting party is using.
-This will retrieve and list the shared identity attributes.
-The above command will also work if the user is currently offline since the attributes are retrieved from GNS.
-Further, $TICKET can be re-used later to retrieve up-to-date attributes in case "friend" has changed the value(s). For instance, because his email address changed.
-To list all given authorizations (tickets) you can execute:
-@example
-$ gnunet-reclaim -e "user" -T
-@end example
-@node Revoking Authorizations of Third Parties
-@subsection Revoking Authorizations of Third Parties
-If you want to revoke the access of a third party to your attributes you can execute:
-@example
-$ gnunet-reclaim -e "user" -R $TICKET
-@end example
-This will prevent the third party from accessing the attribute in the future.
-Please note that if the third party has previously accessed the attribute, there is not way in which the system could have prevented the thiry party from storing the data.
-As such, only access to updated data in the future can be revoked.
-This behaviour is _exactly the same_ as with other IdPs.
-@node OpenID Connect
-@subsection OpenID Connect
-There is an @uref{OpenID Connect, https://openid.net/specs/openid-connect-core-1_0.html} API for use with re:claimID.
-However, its use is quite complicated to setup.
-@example
-https://api.reclaim/openid/authorize
-http://localhost:7776/openid/token
-http://localhost:7776/openid/userinfo
-http://localhost:7776/openid/login
-@end example
-The token endpoint is protected using HTTP basic authentication.
-You can authenticate using any username and the password configured under:
-@example
-$ gnunet-config -s reclaim-rest-plugin -o OIDC_CLIENT_SECRET
-@end example
-The authorize endpoint is protected using a Cookie which can be obtained through
-a request against the login endpoint.
-This functionality is meant to be used in the context of the OpenID Connect authorization
-flow to collect user consent interactively.
-Without a Cookie, the authorize endpoint redirects to a URI configured under:
-@example
-$ gnunet-config -s reclaim-rest-plugin -o ADDRESS
-@end example
-The token endpoint is protected using OAuth2 and expects the grant
-which is retrieved from the authorization endpoint according to the standard.
-The userinfo endpoint is protected using OAuth2 and expects a bearer access
-token which is retrieved from a token request.
-In order to make use of OpenID Connect flows as a user, you need to install
-the browser plugin:
-@itemize @bullet
-@item @uref{https://addons.mozilla.org/addon/reclaimid/, Firefox Add-on}
-@item @uref{https://chrome.google.com/webstore/detail/reclaimid/jiogompmdejcnacmlnjhnaicgkefcfll, Chrome Web Store}
-@end itemize
-In order to create and register an OpenID Connect client as a relying party,
-you need to execute the following steps:
-@example
-$ gnunet-identity -C <client_name>
-$ gnunet-namestore -z <client_name> -a -n "@@" -t RECLAIM_OIDC_REDIRECT -V <redirect_uri> -e 1d -p
-$ gnunet-namestore -z <client_name> -a -n "@@" -t RECLAIM_OIDC_CLIENT -V "My OIDC Client" -e 1d -p
-@end example
-The "client_id" for use in OpenID Connect is the public key of the client as
-displayed using:
-@example
-$ gnunet-identity -d grep "relyingparty" | awk '@{print $3@}'
-@end example
-The RECLAIM_OIDC_REDIRECT record contains your website redirect URI.
-You may use any globally unique DNS or GNS URI.
-The RECLAIM_OIDC_CLIENT record represents the client description which whill
-be displayed to users in an authorization request.
-Any website or relying party must use the authorization endpoint
-@uref{https://api.reclaim/openid/authorize} in its authorization redirects, e.g.
-@example
-<a href="https://api.reclaim/openid/authorize?client_id=<PKEY>\
-                                             &scope=openid email\
-                                             &redirect_uri=<redirect_uri>\
-                                             &nonce=<random>">Login</a>
-@end example
-This will direct the user's browser onto his local reclaimID instance.
-After giving consent, you will be provided with the OpenID Connect authorization
-code according to the specifications at your provided redirect URI.
-The ID Tokens issues by the token endpoints are signed using HS512 with the
-shared secret configured under:
-@example
-$ gnunet-config -s reclaim-rest-plugin -o JWT_SECRET
-@end example
-The authorization code flow optionally supports @uref{https://tools.ietf.org/html/rfc7636, Proof Key for Code Exchange}.
-If PKCE is used, the client does not need to authenticate against the token
-endpoint.
-@node Providing Third Party Attestation
-@subsection Providing Third Party Attestation
-If you are running an identity provider (IdP) service you may be able to
-support providing credentials for re:claimID users.
-IdPs can issue JWT credentials as long as they support OpenID Connect and
-@uref{https://openid.net/specs/openid-connect-discovery-1_0.html,OpenID Connect Discovery}.
-In order to allow users to import attributes through the re:claimID user interface,
-you need to register the following public OAuth2/OIDC client:
-@itemize @bullet
-@item client_id: reclaimid
-@item client_secret: none
-@item redirect_uri: https://ui.reclaim (The URI of the re:claimID webextension)
-@item grant_type: authorization_code with PKCE (@uref{https://tools.ietf.org/html/rfc7636, RFC7636})
-@item scopes: all you want to offer.
-@item id_token: JWT
-@end itemize
-When your users add an attribute with name "email" which supports webfinger
-discovery they will be prompted with the option to retrieve the OpenID Connect
-ID Token through the user interface.
-@node Using the Virtual Public Network
-@section Using the Virtual Public Network
-@menu
-* Setting up an Exit node::
-* Fedora and the Firewall::
-* Setting up VPN node for protocol translation and tunneling::
-@end menu
-Using the GNUnet Virtual Public Network (VPN) application you can
-tunnel IP traffic over GNUnet. Moreover, the VPN comes
-with built-in protocol translation and DNS-ALG support, enabling
-IPv4-to-IPv6 protocol translation (in both directions).
-This chapter documents how to use the GNUnet VPN.
-The first thing to note about the GNUnet VPN is that it is a public
-network. All participating peers can participate and there is no
-secret key to control access. So unlike common virtual private
-networks, the GNUnet VPN is not useful as a means to provide a
-"private" network abstraction over the Internet. The GNUnet VPN
-is a virtual network in the sense that it is an overlay over the
-Internet, using its own routing mechanisms and can also use an
-internal addressing scheme. The GNUnet VPN is an Internet
-underlay --- TCP/IP applications run on top of it.
-The VPN is currently only supported on GNU/Linux systems.
-Support for operating systems that support TUN (such as FreeBSD)
-should be easy to add (or might not even require any coding at
-all --- we just did not test this so far). Support for other
-operating systems would require re-writing the code to create virtual
-network interfaces and to intercept DNS requests.
-The VPN does not provide good anonymity. While requests are routed
-over the GNUnet network, other peers can directly see the source
-and destination of each (encapsulated) IP packet. Finally, if you
-use the VPN to access Internet services, the peer sending the
-request to the Internet will be able to observe and even alter
-the IP traffic. We will discuss additional security implications
-of using the VPN later in this chapter.
-@node Setting up an Exit node
-@subsection Setting up an Exit node
-Any useful operation with the VPN requires the existence of an exit
-node in the GNUnet Peer-to-Peer network. Exit functionality can only
-be enabled on peers that have regular Internet access. If you want
-to play around with the VPN or support the network, we encourage
-you to setup exit nodes. This chapter documents how to setup an
-exit node.
-There are four types of exit functions an exit node can provide,
-and using the GNUnet VPN to access the Internet will only work
-nicely if the first three types are provided somewhere in
-the network. The four exit functions are:
-@itemize @bullet
-@item DNS: allow other peers to use your DNS resolver
-@item IPv4: allow other peers to access your IPv4 Internet connection
-@item IPv6: allow other peers to access your IPv6 Internet connection
-@item Local service: allow other peers to access a specific TCP or
-UDP service your peer is providing
-@end itemize
-By enabling "exit" in gnunet-setup and checking the respective boxes
-in the "exit" tab, you can easily choose which of the above exit
-functions you want to support.
-Note, however, that by supporting the first three functions you will
-allow arbitrary other GNUnet users to access the Internet via your
-system. This is somewhat similar to running a Tor exit node. The
-Torproject has a nice article about what to consider if you want
-to do this here. We believe that generally running a DNS exit node
-is completely harmless.
-The exit node configuration does currently not allow you to restrict the
-Internet traffic that leaves your system. In particular, you cannot
-exclude SMTP traffic (or block port 25) or limit to HTTP traffic using
-the GNUnet configuration. However, you can use your host firewall to
-restrict outbound connections from the virtual tunnel interface. This
-is highly recommended. In the future, we plan to offer a wider range
-of configuration options for exit nodes.
-Note that by running an exit node GNUnet will configure your kernel
-to perform IP-forwarding (for IPv6) and NAT (for IPv4) so that the
-traffic from the virtual interface can be routed to the Internet.
-In order to provide an IPv6-exit, you need to have a subnet routed
-to your host's external network interface and assign a subrange of
-that subnet to the GNUnet exit's TUN interface.
-When running a local service, you should make sure that the local
-service is (also) bound to the IP address of your EXIT interface
-(e.g. 169.254.86.1). It will NOT work if your local service is
-just bound to loopback. You may also want to create a "VPN" record
-in your zone of the GNU Name System to make it easy for others to
-access your service via a name instead of just the full service
-descriptor. Note that the identifier you assign the service can
-serve as a passphrase or shared secret, clients connecting to the
-service must somehow learn the service's name. VPN records in the
-GNU Name System can make this easier.
-@node Fedora and the Firewall
-@subsection Fedora and the Firewall
-When using an exit node on Fedora 15, the standard firewall can
-create trouble even when not really exiting the local system!
-For IPv4, the standard rules seem fine. However, for IPv6 the
-standard rules prohibit traffic from the network range of the
-virtual interface created by the exit daemon to the local IPv6
-address of the same interface (which is essentially loopback
-traffic, so you might suspect that a standard firewall would
-leave this traffic alone). However, as somehow for IPv6 the
-traffic is not recognized as originating from the local
-system (and as the connection is not already "established"),
-the firewall drops the traffic. You should still get ICMPv6
-packets back, but that's obviously not very useful.
-Possible ways to fix this include disabling the firewall (do you
-have a good reason for having it on?) or disabling the firewall
-at least for the GNUnet exit interface (or the respective
-IPv4/IPv6 address range). The best way to diagnose these kinds
-of problems in general involves setting the firewall to REJECT
-instead of DROP and to watch the traffic using wireshark
-(or tcpdump) to see if ICMP messages are generated when running
-some tests that should work.
-@node Setting up VPN node for protocol translation and tunneling
-@subsection Setting up VPN node for protocol translation and tunneling
-The GNUnet VPN/PT subsystem enables you to tunnel IP traffic over the
-VPN to an exit node, from where it can then be forwarded to the
-Internet. This section documents how to setup VPN/PT on a node.
-Note that you can enable both the VPN and an exit on the same peer.
-In this case, IP traffic from your system may enter your peer's VPN
-and leave your peer's exit. This can be useful as a means to do
-protocol translation. For example, you might have an application that
-supports only IPv4 but needs to access an IPv6-only site. In this case,
-GNUnet would perform 4to6 protocol translation between the VPN (IPv4)
-and the Exit (IPv6). Similarly, 6to4 protocol translation is also
-possible. However, the primary use for GNUnet would be to access
-an Internet service running with an IP version that is not supported
-by your ISP. In this case, your IP traffic would be routed via GNUnet
-to a peer that has access to the Internet with the desired IP version.
-Setting up an entry node into the GNUnet VPN primarily requires you
-to enable the "VPN/PT" option in "gnunet-setup". This will launch the
-"gnunet-service-vpn", "gnunet-service-dns" and "gnunet-daemon-pt"
-processes. The "gnunet-service-vpn" will create a virtual interface
-which will be used as the target for your IP traffic that enters the
-VPN. Additionally, a second virtual interface will be created by
-the "gnunet-service-dns" for your DNS traffic. You will then need to
-specify which traffic you want to tunnel over GNUnet. If your ISP only
-provides you with IPv4 or IPv6-access, you may choose to tunnel the
-other IP protocol over the GNUnet VPN. If you do not have an ISP
-(and are connected to other GNUnet peers via WLAN), you can also
-choose to tunnel all IP traffic over GNUnet. This might also provide
-you with some anonymity. After you enable the respective options
-and restart your peer, your Internet traffic should be tunneled
-over the GNUnet VPN.
-The GNUnet VPN uses DNS-ALG to hijack your IP traffic. Whenever an
-application resolves a hostname (like 'gnunet.org'), the
-"gnunet-daemon-pt" will instruct the "gnunet-service-dns" to intercept
-the request (possibly route it over GNUnet as well) and replace the
-normal answer with an IP in the range of the VPN's interface.
-"gnunet-daemon-pt" will then tell "gnunet-service-vpn" to forward all
-traffic it receives on the TUN interface via the VPN to the original
-destination.
-For applications that do not use DNS, you can also manually create
-such a mapping using the gnunet-vpn command-line tool. Here, you
-specify the desired address family of the result (e.g. "-4"), and the
-intended target IP on the Internet (e.g. "-i 131.159.74.67") and
-"gnunet-vpn" will tell you which IP address in the range of your
-VPN tunnel was mapped.
-@command{gnunet-vpn} can also be used to access "internal" services
-offered by GNUnet nodes. So if you happen to know a peer and a
-service offered by that peer, you can create an IP tunnel to
-that peer by specifying the peer's identity, service name and
-protocol (--tcp or --udp) and you will again receive an IP address
-that will terminate at the respective peer's service.
-@node Using the GNUnet Messenger
-@section Using the GNUnet Messenger
-The GNUnet Messenger subsystem allows decentralized message-based 
-communication inside of so called rooms. Each room can be relayed by
-a variable amount of peers. Every member of a room has the possibility
-to relay the room on its own peer. A peer allows any amount of members 
-to join a room. The amount of members in a room is not restricted.
-Messages in a room will be distributed between all peers relaying the 
-room or being internally (in context of the messenger service) connected 
-to a relaying peer. All received or sent messages will be stored on any 
-peer locally which is relaying the respective room or is internally
-connected to such a relaying peer.
-The Messenger service is built on the CADET subsystem to make internal 
-connections between peers using a reliable and encrypted transmission. 
-Additionally the service uses a discrete padding to few different sizes. 
-So kinds of messages and potential content can't be identified by the 
-size of traffic from any attacker being unable to break the encryption 
-of the transmission layer.
-Another feature is additional end-to-end encryption for selected messages
-which uses the public key of another member (the receiver) to encrypt 
-the message. Therefore it is ensured that only the selected member can
-read its content. This will also use additional padding.
-@menu
-* Current state::
-* Entering a room::
-* Opening a room::
-* Messaging in a room::
-* Private messaging::
-@end menu
-@node Current state
-@subsection Current state
-Currently there is only a simplistic CLI application available to use the
-messenger service. You can use this application with the 
-@command{gnunet-messenger} command.
-This application was designed for testing purposes and it does not provide
-full functionality in the current state. It is planned to replace this CLI
-application in later stages with a fully featured one using a client-side
-library designed for messenger applications.
-@node Entering a room
-@subsection Entering a room
-You can enter any room by its ROOMKEY and any PEERIDENTITY of a relaying 
-peer. Optionally you can provide any IDENTITY which can represent a local 
-ego by its name.
-@example
-$ gnunet-messenger [-e IDENTITY] -d PEERIDENTITY -r ROOMKEY
-@end example
-A PEERIDENTITY gets entered in encoded form. You can get your own peer ID by
-using the @command{gnunet-peerinfo} command:
-@example
-$ gnunet-peerinfo -s
-@end example
-A ROOMKEY gets entered in readable text form. The service will then hash the 
-entered ROOMKEY and use the result as shared secret for transmission through 
-the CADET submodule. You can also optionally leave out the '-r' parameter and 
-the ROOMKEY to use the zeroed hash instead.
-If no IDENTITY is provided you will not send any name to others, you will be 
-referred as "anonymous" instead and use the anonymous ego. If you provide any 
-IDENTITY a matching ego will be used to sign your messages. If there is no 
-matching ego you will use the anonymous ego instead. The provided IDENTITY will
-be distributed as your name for the service in any case.
-@node Opening a room
-@subsection Opening a room
-You can open any room in a similar way to entering it. You just have to leave
-out the '-d' parameter and the PEERIDENTITY of the relaying peer.
-@example
-$ gnunet-messenger [-e IDENTITY] -r ROOMKEY
-@end example
-Providing ROOMKEY and IDENTITY is identical to entering a room. Opening a room
-will also make your peer to a relay of this room. So others can enter the room
-through your peer if they have the required ROOMKEY and your peer ID.
-If you want to use the zeroed hash as shared secret key for the room you can
-also leave it out as well:
-@example
-$ gnunet-messenger
-@end example
-@node Messaging in a room
-@subsection Messaging in a room
-Once joined a room by entering it or opening it you can write text-based 
-messages which will be distributed between all internally conntected peers. All 
-sent messages will be displayed in the same way as received messages.
-This relates to the internal handling of sent and received messages being mostly
-identical on application layer. Every handled message will be represented
-visually depending on its kind, content and sender. A sender can usually be 
-identified by the encoded member ID or their name.
-@example
-[17X37K] * 'anonymous' says: "hey"
-@end example
-@node Private messaging
-@subsection Private messaging
-As referred in the introduction the service allows sending private messages with
-additional end-to-end encryption. These messages will be visually represented
-by messages of the kind 'PRIVATE' in case they can't be decrypted with your used
-ego. Members who can't decrypt the message can potentially only identify its 
-sender but they can't identify its receiver.
-@example
-[17X37K] ~ message: PRIVATE
-@end example
-If they can be decrypted they will appear as their secret message instead
-but marked visually.
-@example
-[17X37K] ** 'anonymous' says: "hey"
-@end example
-Currently you can only activate sending such encrypted text messages instead of 
-usual text messages by adding the '-p' parameter:
-@example
-$ gnunet-messenger [-e IDENTITY] -d PEERIDENTITY -r ROOMKEY -p
-@end example
-Notice that you can only send such encrypted messages to members who use an ego
-which is not publicly known as the anonymous ego to ensure transparency. If 
-any user could decrypt these messages they would not be private. So as receiver
-of such messages the IDENTITY is required and it has to match a local ego.
diff --git a/doc/handbook/chapters/vocabulary.texi b/doc/handbook/chapters/vocabulary.texi
deleted file mode 100644
index 0ee472b95..000000000
--- a/doc/handbook/chapters/vocabulary.texi
+++ /dev/null
@@ -1,72 +0,0 @@
-@node Vocabulary
-@chapter Vocabulary
-@menu
-* Definitions abbreviations and acronyms::
-* Words and characters::
-* Technical Assumptions::
-@end menu
-Throughout this Reference Manual we will use certain words and characters
-which are listed in this introductionary chapter.
-@node Definitions abbreviations and acronyms
-@section Definitions abbreviations and acronyms
-@menu
-* Definitions::
-@end menu
-@node Definitions
-@subsection Definitions
-Throughout this Reference Manual, the following terms and definitions
-apply.
-@node Words and characters
-@section Words and characters
-@enumerate
-@item
-In chapter Installation Handbook,
-``@command{#}'' in example code blocks describes commands executed as root
-@example
-# echo "I am root"
-I am root
-@end example
-@item
-However, in the chapter GNUnet C Tutorial
-``@command{#}'' in example code blocks describes commands, ie comments.
-@example
-# Do the foobar thing:
-$ make foobar
-@end example
-@item
-Dollarsign ``@command{$}'' in example code blocks describes commands you
-execute as unprivileged users.
-@example
-$ cd foo; ./configure --example-switch
-@end example
-@item
-Backslash ``@command{\}'' describes linebreaks.
-@example
-./configure --foo --bar --baz \
- --short-loop
-@end example
-...expands to @code{./configure --foo --bar --baz --short-loop}
-@end enumerate
-@node Technical Assumptions
-@section Technical Assumptions
-@c Is it really assuming Bash (ie Bash extensions of POSIX being used)?
-The shell on GNU systems is assumed to be Bash.
author	Martin Schanzenbach <schanzen@gnunet.org>	2022-08-02 17:25:41 +0200
committer	Martin Schanzenbach <schanzen@gnunet.org>	2022-08-02 17:25:41 +0200
commit	4fe567d9d94b9159254a2f2cce64855a794d9699 (patch)
tree	b286f5a454472ec92ff88376b297e411e64c5843 /doc/handbook/chapters
parent	e8b7707f833739851227d4865e6c6064865f19ec (diff)
download	gnunet-4fe567d9d94b9159254a2f2cce64855a794d9699.tar.gz gnunet-4fe567d9d94b9159254a2f2cce64855a794d9699.zip