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-@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 Free software under the GNU General Public License, with a community
-that believes in the GNU philosophy
-@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. C and Java 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 manual is far from complete, and we
-welcome informed contributions, be it in the form of new chapters or
-insightful comments.
-
-However, the website is experiencing a constant onslaught of sophisticated
-link-spam entered manually by exploited workers solving puzzles and
-customizing text. To limit this commercial defacement, we are strictly
-moderating comments and have disallowed "normal" users from posting new
-content. However, this is really only intended to keep the spam at bay. If
-you are a real user or aspiring developer, please drop us a note
-(IRC, e-mail, contact form) with your user profile ID number included.
-We will then relax these restrictions on your account. We're sorry for
-this inconvenience; however, few people would want to read this site
-if 99% of it was advertisements for bogus websites.
-
-
-
-@c ***********************************************************************
-
-
-
-
-
-
-
-
-@menu
-* Developer Introduction::
-* 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::
-* GNUnet's TESTING library::
-* Performance regression analysis with Gauger::
-* GNUnet's TESTBED Subsystem::
-* libgnunetutil::
-* The Automatic Restart Manager (ARM)::
-* GNUnet's TRANSPORT Subsystem::
-* NAT library::
-* Distance-Vector plugin::
-* SMTP plugin::
-* Bluetooth plugin::
-* WLAN plugin::
-* The ATS Subsystem::
-* GNUnet's CORE Subsystem::
-* GNUnet's CADET subsystem::
-* GNUnet's NSE subsystem::
-* GNUnet's HOSTLIST subsystem::
-* GNUnet's IDENTITY subsystem::
-* GNUnet's NAMESTORE Subsystem::
-* GNUnet's PEERINFO subsystem::
-* GNUnet's PEERSTORE subsystem::
-* GNUnet's SET Subsystem::
-* GNUnet's STATISTICS subsystem::
-* GNUnet's Distributed Hash Table (DHT)::
-* The GNU Name System (GNS)::
-* The GNS Namecache::
-* The REVOCATION Subsystem::
-* GNUnet's File-sharing (FS) Subsystem::
-* GNUnet's REGEX 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 GNUnet tutorials for C and java
-available in the @file{src/} directory of the repository or under the
-following links:
-
-@c ** FIXME: Link to files in source, not online.
-@c ** FIXME: Where is the Java tutorial?
-@itemize @bullet
-@item @uref{https://gnunet.org/git/gnunet.git/plain/doc/gnunet-c-tutoria
-l.pdf, GNUnet C tutorial}
-@item GNUnet Java tutorial
-@end itemize
-
-In addition to this book, the GNUnet server contains various resources for
-GNUnet developers. They are all conveniently reachable via the "Developer"
-entry in the navigation menu. Some additional tools (such as static
-analysis reports) require a special developer access to perform certain
-operations. If you feel you need access, you should contact
-@uref{http://grothoff.org/christian/, Christian Grothoff},
-GNUnet's maintainer.
-
-The public subsystems on the GNUnet server that help developers are:
-
-@itemize @bullet
-@item The Version control system keeps our code and enables distributed
-development. Only developers with write access can commit code, everyone
-else is encouraged to submit patches to the
-@uref{https://lists.gnu.org/mailman/listinfo/gnunet-developers,
-GNUnet-developers mailinglist}.
-@item The GNUnet bugtracking system is used to track feature requests,
-open bug reports and their resolutions. Anyone can report bugs, only
-developers can claim to have fixed them.
-@item A buildbot is used to check GNUnet builds automatically on a range
-of platforms. Builds are triggered automatically after 30 minutes of no
-changes to Git.
-@item The current quality of our automated test suite is assessed using
-Code coverage analysis. This analysis is run daily; however the webpage
-is only updated if all automated tests pass at that time. Testcases that
-improve our code coverage are always welcome.
-@item We try to automatically find bugs using a static analysis scan.
-This scan is run daily; however the webpage is only updated if all
-automated tests pass at the time. 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.
-@item We use Gauger for automatic performance regression visualization.
-Details on how to use Gauger are here.
-@item We use @uref{http://junit.org/, junit} to automatically test
-gnunet-java. Automatically generated, current reports on the test suite
-are here.
-@item We use Cobertura to generate test coverage reports for gnunet-java.
-Current reports on test coverage 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 gnunet Core of the P2P framework, including file-sharing, VPN and
-chat applications; this is what the developer handbook covers mostly
-@item gnunet-gtk Gtk+-based user interfaces, including gnunet-fs-gtk
-(file-sharing), gnunet-statistics-gtk (statistics over time),
-gnunet-peerinfo-gtk (information about current connections and known
-peers), gnunet-chat-gtk (chat GUI) and gnunet-setup (setup tool for
-"everything")
-@item gnunet-fuse Mounting directories shared via GNUnet's file-sharing
-on Linux
-@item gnunet-update Installation and update tool
-@item gnunet-ext Template for starting 'external' GNUnet projects
-@item gnunet-java Java APIs for writing GNUnet services and applications
-@c ** FIXME: Point to new website repository once we have it:
-@c ** @item svn/gnunet-www/ Code and media helping drive the GNUnet
-website
-@item 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 gnunet-qt qt-based GNUnet GUI (dead?)
-@item gnunet-cocoa cocoa-based GNUnet GUI (dead?)
-
-@end table
-
-We are also working on various supporting libraries and tools:
-@c ** FIXME: What about gauger, and what about libmwmodem?
-
-@table @asis
-@item libextractor GNU libextractor (meta data extraction)
-@item libmicrohttpd GNU libmicrohttpd (embedded HTTP(S) server library)
-@item gauger Tool for performance regression analysis
-@item monkey Tool for automated debugging of distributed systems
-@item libmwmodem Library for accessing satellite connection quality
-reports
-@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 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 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.
-@item 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 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 wapper around block plugins which provide the necessary
-functions for each block type.
-@item statistics/ The statistics service enables associating
-values (of type uint64_t) with a componenet name and a string. The main
-uses is debugging (counting events), performance tracking and user
-entertainment (what did my peer do today?).
-@item 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 peerinfo/ 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 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 datastore/ 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 template/ Template for writing a new service. Does nothing.
-@item ats/ 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 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 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 reliabily (with acknowledgement, retransmission, timeouts,
-etc.).
-@item transport/ 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 (i.e.
-friends-only).
-@item peerinfo-tool/
-This directory contains the gnunet-peerinfo binary which can be used to
-inspect the peers and HELLOs known to the peerinfo service.
-@item 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 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 testbed/ The testbed service is
-used for creating small or large scale deployments of GNUnet peers for
-evaluation of protocols. It facilitates peer depolyments on multiple
-hosts (for example, in a cluster) and establishing varous network
-topologies (both underlay and overlay).
-@item nse/ The network size estimation (NSE) service
-implements a protocol for (securely) estimating the current size of the
-P2P network.
-@item dht/ 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 hostlist/ 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 topology/ 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 fs/ 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 cadet/ 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 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 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 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 vpn/ 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 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 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 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 revocation/ Key revocation service, can be used to revoke the
-private key of an identity if it has been compromised
-@item 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 namestore/ Database
-for the GNU name system with per-user private information, persistence
-required
-@item gns/ GNU name system, a GNU approach to DNS and PKI.
-@item 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 regex/ Service for the (distributed) evaluation of
-regular expressions.
-@item 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 consensus/ The consensus service will allow a set
-of peers to agree on a set of values via a distributed set union
-computation.
-@item rest/ The rest API allows access to GNUnet services using RESTful
-interaction. The services provide plugins that can exposed by the rest
-server.
-@item experimentation/ The experimentation daemon coordinates distributed
-experimentation to evaluate transport and ats properties
-@end table
-
-@c ***********************************************************************
-@node System Architecture
-@section System Architecture
-
-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:
-
-@c images here
-
-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:
-
-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).
-
-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 page 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 stable @tab stable @tab stable
-@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::
-@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 plibc.h --- external library
-@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 GNUNET_log_setup
-(i.e. 'core') and log using plain 'GNUNET_log'.
-@item command-line tools use their full name in GNUNET_log_setup (i.e.
-'gnunet-publish') and log using plain 'GNUNET_log'.
-@item service access libraries log using 'GNUNET_log_from' and use
-'DIRNAME-api' for the component (i.e. 'core-api')
-@item pure libraries (without associated service) use 'GNUNET_log_from'
-with the component set to their library name (without lib or '.so'),
-which should also be their directory name (i.e. 'nat')
-@item plugins should use 'GNUNET_log_from' with the directory name and the
-plugin name combined to produce the component name (i.e. 'transport-tcp').
-@item logging should be unified per-file by defining a LOG macro with the
-appropriate arguments, along these lines:@ #define LOG(kind,...)
-GNUNET_log_from (kind, "example-api",__VA_ARGS__)
-@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 (src/MODULE) are under [MODULE]
-@item options for a plugin of a module are under [MODULE-PLUGINNAME]
-@end itemize
-
-@c ***********************************************************************
-@node exported symbols
-@subsubsection exported symbols
-
-@itemize @bullet
-@item must start with "GNUNET_modulename_" and be defined in
-"modulename.c"
-@item exceptions: those defined in 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 src/modulename/ and NEVER be@ declared
-in src/include/.
-@end itemize
-
-@node testcases
-@subsubsection testcases
-
-@itemize @bullet
-@item must be called "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 "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 HAVE_BENCHMARKS is satisfied
-@end itemize
-
-@c ***********************************************************************
-@node src/ directories
-@subsubsection src/ directories
-
-@itemize @bullet
-@item gnunet-NAME: end-user applications (i.e., gnunet-search, gnunet-arm)
-@item gnunet-service-NAME: service processes with accessor library (i.e.,
-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 (i.e.,
-gnunet-daemon-hostlist) and no GNUnet management port
-@item libgnunet_plugin_DIR_NAME: loadable plugins (i.e.,
-libgnunet_plugin_transport_tcp)
-@end itemize
-
-@c ***********************************************************************
-@node Coding style
-@subsection Coding style
-
-@itemize @bullet
-@item GNU guidelines generally apply
-@item Indentation is done with spaces, two per level, no tabs
-@item C99 struct initialization is fine
-@item declare only one variable per line, so@
-
-@example
-int i; int j;
-@end example
-
-instead of
-
-@example
-int i,j;
-@end example
-
-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 'true' target being either the
-'error' case or the significantly simpler continuation. For example:
-
-@example
-if (0 != stat ("filename," &sbuf)) @{ error(); @} else @{
-  /* handle normal case here */
-@}
-@end example
-
-instead of
-
-@example
-if (stat ("filename," &sbuf) == 0) @{
-  /* handle normal case here */
-@} else @{ error(); @}
-@end example
-
-If possible, the error clause should be terminated with a 'return' (or
-'goto' to some cleanup routine) and in this case, the '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 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
-
-
-Note that splitting the @code{if} statement above is debateable 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).
-@end itemize
-
-@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 "if HAVE_EXPERIMENTAL" in
-your 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 coverage.sh script in
-@file{contrib/}.
-
-@c ***********************************************************************
-@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:
-
-@code{git clone https://gnunet.org/git/gnunet-ext.git}
-
-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
-
-@code{export LD_LIBRARY_PATH=/path/to/gnunet/lib}
-
-@c ***********************************************************************
-@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 "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 @code{Makefile.am} in the directory
-containing the testcase. For a testcase testing the code in @code{foo.c}
-the @code{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 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 ***********************************************************************
-@node GNUnet's TESTING library
-@section GNUnet's 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
-
-@c ***********************************************************************
-@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 12000 - 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 funciton
-@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 successfull, this function returs 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 cancelled 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).
-
-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 performace 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 accesed 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 dependant 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.
-
-@c ***********************************************************************
-@node GNUnet's TESTBED Subsystem
-@section GNUnet's 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 int the above command string also allows for
-substitions. 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 @code{%u@@%h}
-doesn't work either. If you want to user username substitutions for SSH
-use the argument @code{-l} before the username substitution.
-Ex: @code{ssh -l %u -p %p %h}
-
-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
-`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
-`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 "gnunet_testbed_service.h" file and
-linking with -lgnunettestbed.
-
-
-
-@c ***********************************************************************
-@menu
-* Supported Topologies::
-* Hosts file format::
-* Topology file format::
-* Testbed Barriers::
-* Automatic large-scale deployment of GNUnet in the PlanetLab testbed::
-* 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 probabililty to well connected peers.
-@footnote{See Emergence of Scaling in Random Networks. Science 286,
-509-512, 1999.}
-
-@item @code{GNUNET_TESTBED_TOPOLOGY_FROM_FILE}: The topology information
-is loaded from a file. The path to the file has to be given. See 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 atleast 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. See Topology file format for the format of this file.
-
-@c ***********************************************************************
-@node Hosts file format
-@subsection Hosts file format
-
-The testbed API offers the function 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, 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:
-@code{<username>@@<hostname>:<port>}
-@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 seperated 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
-initialse a barrier in the experiment
-@item @strong{@code{GNUNET_TESTBED_barrier_cancel()}:} function to cancel
-a barrier which has been initialised 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.
-
-@c ***********************************************************************
-@node Automatic large-scale deployment of GNUnet in the PlanetLab testbed
-@subsection Automatic large-scale deployment of GNUnet in the PlanetLab testbed
-
-PlanetLab is as a testbed for computer networking and distributed systems
-research. It was established in 2002 and as of June 2010 was composed of
-1090 nodes at 507 sites worldwide.
-
-To automate the GNUnet we created a set of automation tools to simplify
-the large-scale deployment. We provide you a set of scripts you can use
-to deploy GNUnet on a set of nodes and manage your installation.
-
-Please also check @uref{https://gnunet.org/installation-fedora8-svn} and
-@uref{https://gnunet.org/installation-fedora12-svn} to find detailled
-instructions how to install GNUnet on a PlanetLab node.
-
-
-@c ***********************************************************************
-@menu
-* PlanetLab Automation for Fedora8 nodes::
-* Install buildslave on PlanetLab nodes running fedora core 8::
-* Setup a new PlanetLab testbed using GPLMT::
-* Why do i get an ssh error when using the regex profiler?::
-@end menu
-
-@node PlanetLab Automation for Fedora8 nodes
-@subsubsection PlanetLab Automation for Fedora8 nodes
-
-@c ***********************************************************************
-@node Install buildslave on PlanetLab nodes running fedora core 8
-@subsubsection Install buildslave on PlanetLab nodes running fedora core 8
-@c ** Actually this is a subsubsubsection, but must be fixed differently
-@c ** as subsubsection is the lowest.
-
-Since most of the PlanetLab nodes are running the very old fedora core 8
-image, installing the buildslave software is quite some pain. For our
-PlanetLab testbed we figured out how to install the buildslave software
-best.
-
-@c This is a vvery terrible way to suggest installing software.
-@c FIXME: Is there an official, safer way instead of blind-piping a
-@c script?
-@c FIXME: Use newer pypi URLs below.
-Install Distribute for python:@ @code{@ curl
-http://python-distribute.org/distribute_setup.py | sudo python@ }
-
-Install Distribute for zope.interface <= 3.8.0 (4.0 and 4.0.1 will not
-work):
-
-@example
-wget https://pypi.python.org/packages/source/z/zope.interface/zope.interface-3.8.0.tar.gz
-tar zvfz zope.interface-3.8.0.tar.gz@ cd zope.interface-3.8.0
-sudo python setup.py install
-@end example
-
-Install the buildslave software (0.8.6 was the latest version):
-
-@example
-wget http://buildbot.googlecode.com/files/buildbot-slave-0.8.6p1.tar.gz
-tar xvfz buildbot-slave-0.8.6p1.tar.gz@ cd buildslave-0.8.6p1
-sudo python setup.py install
-@end example
-
-The setup will download the matching twisted package and install it.
-It will also try to install the latest version of zope.interface which
-will fail to install. Buildslave will work anyway since version 3.8.0
-was installed before!
-
-@c ***********************************************************************
-@node Setup a new PlanetLab testbed using GPLMT
-@subsubsection Setup a new PlanetLab testbed using GPLMT
-
-@itemize @bullet
-@item Get a new slice and assign nodes
-Ask your PlanetLab PI to give you a new slice and assign the nodes you
-need
-@item Install a buildmaster
-You can stick to the buildbot documentation:@
-@uref{http://buildbot.net/buildbot/docs/current/manual/installation.html}
-@item Install the buildslave software on all nodes
-To install the buildslave on all nodes assigned to your slice you can use
-the tasklist @code{install_buildslave_fc8.xml} provided with GPLMT:
-
-@example
-./gplmt.py -c contrib/tumple_gnunet.conf -t \
-contrib/tasklists/install_buildslave_fc8.xml -a -p <planetlab password>
-@end example
-
-@item Create the buildmaster configuration and the slave setup commands
-
-The master and the and the slaves have need to have credentials and the
-master has to have all nodes configured. This can be done with the
-@code{create_buildbot_configuration.py} script in the @code{scripts}
-directory
-
-This scripts takes a list of nodes retrieved directly from PlanetLab or
-read from a file and a configuration template and creates:
-
-@itemize @bullet
-@item a tasklist which can be executed with gplmt to setup the slaves
-@item a master.cfg file containing a PlanetLab nodes
-@end itemize
-
-A configuration template is included in the <contrib>, most important is
-that the script replaces the following tags in the template:
-
-%GPLMT_BUILDER_DEFINITION :@ GPLMT_BUILDER_SUMMARY@ GPLMT_SLAVES@
-%GPLMT_SCHEDULER_BUILDERS
-
-Create configuration for all nodes assigned to a slice:@ @code{@
-./create_buildbot_configuration.py -u <planetlab username> -p <planetlab
-password> -s <slice> -m <buildmaster+port> -t <template>@ }@ Create
-configuration for some nodes in a file:@ @code{@
-./create_buildbot_configuration.p -f <node_file> -m <buildmaster+port> -t
-<template>@ }
-
-@item Copy the @code{master.cfg} to the buildmaster and start it
-Use @code{buildbot start <basedir>} to start the server
-@item Setup the buildslaves
-@end itemize
-
-@c ***********************************************************************
-@node Why do i get an ssh error when using the regex profiler?
-@subsubsection Why do i get an ssh error when using the regex profiler?
-
-Why do i get an ssh error "Permission denied (publickey,password)." when
-using the regex profiler although passwordless ssh to localhost works
-using publickey and ssh-agent?
-
-You have to generate a public/private-key pair with no password:@
-@code{ssh-keygen -t rsa -b 4096 -f ~/.ssh/id_localhost}@
-and then add the following to your ~/.ssh/config file:
-
-@code{Host 127.0.0.1@ IdentityFile ~/.ssh/id_localhost}
-
-now make sure your hostsfile looks like@
-
-[USERNAME]@@127.0.0.1:22@
-[USERNAME]@@127.0.0.1:22
-
-You can test your setup by running `ssh 127.0.0.1` in a terminal and then
-in the opened session run it again. If you were not asked for a password
-on either login, then you should be good to go.
-
-@c ***********************************************************************
-@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 simple issue is #3993: Your configuration MUST somehow ensure that for
-each peer the CORE service is started when the peer is setup, otherwise
-TESTBED may fail to connect peers when the topology is initialized, as
-TESTBED will start some CORE services but not necessarily all (but it
-relies on all of them running). The easiest way is to set
-'FORCESTART = YES' in the '[core]' section of the configuration file.
-Alternatively, having any service that directly or indirectly depends on
-CORE being started with FORCESTART will also do. This issue largely arises
-if users try to over-optimize by not starting any services with
-FORCESTART.
-
-@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.
-
-@c ***********************************************************************
-@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 endianess 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 queueing (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::
-* The CONTAINER_MDLL API::
-@end menu
-
-@c ***********************************************************************
-@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 deamon 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:@
-
-@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 the 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
-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.
-
-
-@c ***********************************************************************
-@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 GNUNET_log and 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 -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 neccessary to run with -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 readibility 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
-https://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 subsytem before the
-change. Of course you can adapt it to your particular needs, this is only
-a quick example.
-
-@c ***********************************************************************
-@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
-GNUNET_NETWORK_STRUCT_BEGIN
-
-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
-@c %**end of header
-
-
-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
-@c %**end of header
-
-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 edian 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
-@c %**end of header
-
-@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
-@c %**end of header
-
-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 aera.
-
-@c ***********************************************************************
-@node Server - Process request message
-@subsubsection Server - Process request message
-@c %**end of header
-
-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 requst
-message.
-
-@c ***********************************************************************
-@node Server - Response to client
-@subsubsection Server - Response to client
-@c %**end of header
-
-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
-@c %**end of header
-
-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.
-@c %**end of header
-
-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
-
-@c ***********************************************************************
-
-@node Cryptography API
-@subsection Cryptography API
-@c %**end of header
-
-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 permuation 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.
-
-@c ***********************************************************************
-@node Message Queue API
-@subsection Message Queue API
-@c %**end of header
-
-@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 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 empy 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, the 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}
-
-@c ***********************************************************************
-@node Service API
-@subsection Service API
-@c %**end of header
-
-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 GNUNET_SERVICE_run
-function from the program's main function. 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
-GNUNET_SERVICE_Main callback. 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), GNUNET_SERVICE_start and
-related functions provide an alternative to 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 src/ sub-directory, for
-example "statistics". The same string would also be given to
-GNUNET_CLIENT_connect to access the service.
-
-Once a service has been initialized, the program should use the
-GNUNET_SERVICE_Main callback to register message handlers using
-GNUNET_SERVER_add_handlers. The service will already have registered a
-handler for the "TEST" message.
-
-The option bitfield (enum GNUNET_SERVICE_Options) determines how a service
-should behave during shutdown. There are three key strategies:
-
-@table @asis
-
-@item instant (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
-(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
-(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
-@c %**end of header
-
-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
-@c %**end of header
-
-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
-@c %**end of header
-
-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
-@c %**end of header
-
-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
-intiialized 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
-@c %**end of header
-
-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
-@c %**end of header
-
-The new multi hash map code was committed in SVN 24319 (will be in GNUnet
-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.
-
-@c ***********************************************************************
-@node The CONTAINER_MDLL API
-@subsection The CONTAINER_MDLL API
-@c %**end of header
-
-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.
-
-@c ***********************************************************************
-@node The Automatic Restart Manager (ARM)
-@section The Automatic Restart Manager (ARM)
-@c %**end of header
-
-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::
-* Availability2::
-* Reliability::
-@end menu
-
-@c ***********************************************************************
-@node Basic functionality
-@subsection Basic functionality
-@c %**end of header
-
-@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
-@c %**end of header
-
-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:@
-@code{@ $ gnunet-arm -s -c configuration_to_use.conf@ }@
-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 AUTOSTART ARM will listen to UNIX domain socket and/or TCP port of
-the service and start the service on-demand.
-
-@item FORCESTART 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 AUTOSTART) 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 Availability2
-@subsection Availability2
-@c %**end of header
-
-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
-(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
-
-@c ***********************************************************************
-@node GNUnet's TRANSPORT Subsystem
-@section GNUnet's TRANSPORT Subsystem
-@c %**end of header
-
-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
-@c %**end of header
-
-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 capablities by
-those of a global passive adversary in the worst case). The scenarios we
-are concerned about is an attacker, Mallory, giving a 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 HELLO messages do not contain a
-cryptographic signature since other peers must be able to edit
-(i.e. remove) addresses from the 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), it sends a PING message over that connection
-to Bob. Note that in this case, Alice initiated the connection so only
-she knows which address was used for sure (Alice maybe behind NAT, so
-whatever address Bob sees may not be an address Alice knows she has). Bob
-checks that the address given in the PING is actually one of his addresses
-(does not belong to Mallory), and if it is, sends back a PONG (with a
-signature that says that Bob owns/uses the address from the PING). Alice
-checks the signature and is happy if it is valid and the address in the
-PONG is the address she used. This is similar to the 0.8.x protocol where
-the 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 she considers valid.
-
-The PONG message is protected with a nonce/challenge against replay
-attacks and uses an expiration time for the signature (but those are
-almost implementation details).
-
-@node NAT library
-@section NAT library
-@c %**end of header
-
-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
-@c %**end of header
-
-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 propogated 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
-Alice <-> Bob and Bob <-> Carol 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 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.
-
-@node SMTP plugin
-@section SMTP plugin
-@c %**end of header
-
-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.
-
-@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?
-@c %**end of header
-
-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?
-@c %**end of header
-
-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?
-@c %**end of header
-
-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?
-@c %**end of header
-
-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?
-@c %**end of header
-
-We have measured the performance of the UDP, TCP and SMTP transport layer
-directly and when used from an application using the GNUnet core.
-Measureing 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
-miniscule 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 octects 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.
-
-@node Bluetooth plugin
-@section Bluetooth plugin
-@c %**end of header
-
-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?
-@c %**end of header
-
-If you are a Linux user and you want to use the Bluetooth transport plugin
-you should install the 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 necesarry 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.
-
-If you are a Windows user you should have installed the
-@emph{MinGW}/@emph{MSys2} with the latest updates (especially the
-@emph{ws2bth} header). If this is your first build of GNUnet on Windows
-you should check out the SBuild repository. It will semi-automatically
-assembles a @emph{MinGW}/@emph{MSys2} installation with a lot of extra
-packages which are needed for the GNUnet build. So this will ease your
-work!@ Finally you just have to be sure that you have the correct drivers
-for your Bluetooth device installed and that your device is on and in a
-discoverable mode. The Windows Bluetooth Stack supports only the RFCOMM
-protocol so we cannot turn on your device programatically!
-
-@c FIXME: Change to unique title
-@node How does it work2?
-@subsection How does it work2?
-@c %**end of header
-
-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 Linux:
-
-@itemize @bullet
-@item it verifies if the name corresponds to a Bluetooth interface name
-@item it verifies if the iterface 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?
-@c %**end of header
-
-@emph{This section is dedicated for 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 interogate 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 his 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?
-@c %**end of header
-
-On 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?
-@c %**end of header
-
-If you have two Bluetooth devices on the same machine which use 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.
-
-On Windows you cannot test the plugin functionality using two Bluetooth
-devices from the same machine because after you install the drivers there
-will occur some conflicts between the Bluetooth stacks. (At least that is
-what happend on my machine : I wasn't able to use the Bluesoleil stack and
-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 begining 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
-@c %**end of header
-
-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 acceses 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 Linux and Windows
-platforms.
-
-@itemize @bullet
-@item Linux functionality
-@item Windows functionality
-@item Pending Features
-@end itemize
-
-
-
-@menu
-* Linux functionality::
-* THE INITIALIZATION::
-* THE LOOP::
-* Details about the broadcast implementation::
-* Windows functionality::
-* Pending features::
-@end menu
-
-@node Linux functionality
-@subsubsection Linux functionality
-@c %**end of header
-
-In order to implement the plugin functionality on 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 privilegies
-(@emph{Remember that we need to have root privilegies 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 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 privilegies
-
-@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 searche 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
-@c %**end of header
-
-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.
-
-@node Windows functionality
-@subsubsection Windows functionality
-@c %**end of header
-
-For Windows I decided to use the Microsoft Bluetooth stack which has the
-advantage of coming standard from Windows XP SP2. The main disadvantage is
-that it only supports the RFCOMM protocol so we will not be able to have
-a low level control over the Bluetooth device. Therefore it is the user
-responsability to check if the device is up and in the discoverable mode.
-Also there are no tools which could be used for debugging in order to read
-the data coming from and going to a Bluetooth device, which obviously
-hindered my work. Another thing that slowed down the implementation of the
-plugin (besides that I wasn't too accomodated with the win32 API) was that
-there were some bugs on MinGW regarding the Bluetooth. Now they are solved
-but you should keep in mind that you should have the latest updates
-(especially the @emph{ws2bth} header).
-
-Besides the fact that it uses the Windows Sockets, the Windows
-implemenation follows the same principles as the Linux one:
-
-@itemize @bullet
-@item It has a initalization part where it initializes the
-Windows Sockets, creates a RFCOMM socket which will be binded and switched
-to the listening mode and registers a SDP service. In the Microsoft
-Bluetooth API there are two ways to work with the SDP:
-@itemize @bullet
-@item an easy way which works with very simple service records
-@item a hard way which is useful when you need to update or to delete the
-record
-@end itemize
-@end itemize
-
-Since I only needed the SDP service to find out on which port the device
-is listening on and that did not change, I decided to use the easy way.
-In order to register the service I used the @emph{WSASetService} function
-and I generated the @emph{Universally Unique Identifier} with the
-@emph{guidgen.exe} Windows's tool.
-
-In the loop section the only difference from the Linux implementation is
-that I used the GNUNET_NETWORK library for functions like @emph{accept},
-@emph{bind}, @emph{connect} or @emph{select}. I decided to use the
-GNUNET_NETWORK library because I also needed to interact with the STDIN
-and STDOUT handles and on Windows the select function is only defined for
-sockets, and it will not work for arbitrary file handles.
-
-Another difference between Linux and Windows implementation is that in
-Linux, the Bluetooth address is represented in 48 bits while in Windows is
-represented in 64 bits. Therefore I had to do some changes on
-@emph{plugin_transport_wlan} header.
-
-Also, currently on Windows the Bluetooth plugin doesn't have support for
-broadcast messages. When it receives a broadcast message it will skip it.
-
-@node Pending features
-@subsubsection Pending features
-@c %**end of header
-
-@itemize @bullet
-@item Implement the broadcast functionality on Windows @emph{(currently
-working on)}
-@item Implement a testcase for the helper :@ @emph{The testcase
-consists of a program which emaluates 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
-@c %**end of header
-
-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 The ATS Subsystem
-@section The ATS Subsystem
-@c %**end of header
-
-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
-@cindex CORE subsystem
-@node GNUnet's CORE Subsystem
-@section GNUnet's CORE Subsystem
-@c %**end of header
-
-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@footnote{@uref{http://en.wikipedia.org/wiki/Elliptic_curve_
-Diffie%E2%80%93Hellman, Elliptic-curve Diffie---Hellman}}
-powered by Curve25519
-@footnote{@uref{http://cr.yp.to/ecdh.html, Curve25519}} for the key
-exchange and then use symmetric encryption, encrypting with both AES-256
-@footnote{@uref{http://en.wikipedia.org/wiki/Rijndael, AES-256}} and
-Twofish @footnote{@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
-@footnote{@uref{http://ed25519.cr.yp.to/, Ed25519}}, a deterministic
-variant of ECDSA
-@footnote{@uref{http://en.wikipedia.org/wiki/ECDSA, ECDSA}}
-@item integrity protection (using SHA-512
-@footnote{@uref{http://en.wikipedia.org/wiki/SHA-2, SHA-512}} to do
-encrypt-then-MAC
-@footnote{@uref{http://en.wikipedia.org/wiki/Authenticated_encryption,
-encrypt-then-MAC}})
-@item Replay
-@footnote{@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
-@c %**end of header
-
-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"?
-@c %**end of header
-
-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
-@c %**end of header
-
-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, queueing 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
-@c %**end of header
-
-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
-@c %**end of header
-
-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
-@c %**end of header
-
-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
-@c %**end of header
-
-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).
-
-@node The CORE Peer-to-Peer Protocol
-@subsection The CORE Peer-to-Peer Protocol
-@c %**end of header
-
-
-@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
-@c %**end of header
-
-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@footnote{@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-alives)
-@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
-@c %**end of header
-
-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
-@c %**end of header
-
-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
-@footnote{@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@footnote{@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
-@c %**end of header
-
-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
-@node GNUnet's CADET subsystem
-@section GNUnet's 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 destiantion peer
-using one session key and relays the data on multiple "connections",
-independent from the channels.
-
-Each channel has optional paramenters, 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.
-
-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.
-
-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.
-
-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.
-
-If a transmission was requested but before the callback fires it is no
-longer needed, it can be cancelled 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 cancelled.
-
-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}.
-
-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
-@cindex NSE
-@node GNUnet's NSE subsystem
-@section GNUnet's 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 subsytems, 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
-infeasable. 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 artifically
-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
-
-@c %**end of header
-
-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 rouning amount (in this example would be every hour).
-Every repetition is called a round.
-
-@node Timing
-@subsubsection Timing
-@c %**end of header
-
-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 assiciated 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 closests to the target value start broadcasting their ID the first.
-
-@node Controlled Flooding
-@subsubsection Controlled Flooding
-
-@c %**end of header
-
-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 brodcast 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
-
-@c %**end of header
-
-Once the closest ID has been spread across the network each peer gets the
-exact distance betweed 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
-
-@c %**end of header
-
-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 his 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::
-* Examples2::
-@end menu
-
-@node Results
-@subsubsection Results
-
-@c %**end of header
-
-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
-veriation is very high, the average maybe meaningless: the network size is
-changing rapidly).
-
-@node Examples2
-@subsubsection Examples2
-
-@c %**end of header
-
-Let's close with a couple examples.
-
-@table @asis
-
-@item Average: 10, std dev: 1 Here the estimate would be
-2^10 = 1024 peers. @footnote{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. @footnote{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
-
-@c %**end of header
-
-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.
-
-@node The NSE Peer-to-Peer Protocol
-@subsection The NSE Peer-to-Peer Protocol
-
-@c %**end of header
-
-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 his 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 stard 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
-@cindex hostlist subsystem
-@node GNUnet's HOSTLIST subsystem
-@section GNUnet's HOSTLIST subsystem
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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 build-in hostlist server makes it simply convenient to offer this
-service.
-
-
-@menu
-* Features::
-* Limitations2::
-@end menu
-
-@node Features
-@subsubsection Features
-
-@c %**end of header
-
-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 Limitations2
-@subsubsection Limitations2
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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.
-
-@node The HOSTLIST daemon
-@subsection The HOSTLIST daemon
-
-@c %**end of header
-
-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.
-
-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.
-
-@node The HOSTLIST server
-@subsection The HOSTLIST server
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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 a HTTP response and the 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
-
-@c %**end of header
-
-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.
-
-@node The HOSTLIST client
-@subsection The HOSTLIST client
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-persistance and loaded on startup. URLs from the configuration file are
-never discarded.
-
-@node Usage
-@subsection Usage
-
-@c %**end of header
-
-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
-@cindex identity subsystem
-@node GNUnet's IDENTITY subsystem
-@section GNUnet's IDENTITY subsystem
-
-@c %**end of header
-
-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
-@c %**end of header
-
-
-@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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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 cancelled 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
-
-@c %**end of header
-
-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
-@cindex namestore subsystem
-@node GNUnet's NAMESTORE Subsystem
-@section GNUnet's 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 subsytem.
-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
-
-@c %**end of header
-
-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 he has to pass the
-namestore handle, the private key of the zone and the label. He 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
-
-@c %**end of header
-
-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.
-If the client wants to iterate over all the, he passes 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
-
-@c %**end of header
-
-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
-@cindex peerinfo subsystem
-@node GNUnet's PEERINFO subsystem
-@section GNUnet's PEERINFO subsystem
-
-@c %**end of header
-
-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
-* Features2::
-* Limitations3::
-* DeveloperPeer Information::
-* Startup::
-* Managing Information::
-* Obtaining Information::
-* The PEERINFO Client-Service Protocol::
-* libgnunetpeerinfo::
-@end menu
-
-@node Features2
-@subsection Features2
-
-@c %**end of header
-
-@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 Limitations3
-@subsection Limitations3
-
-
-@itemize @bullet
-@item Does not perform HELLO validation
-@end itemize
-
-@node DeveloperPeer Information
-@subsection DeveloperPeer Information
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-disk.
-
-@node Obtaining Information
-@subsection Obtaining Information
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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. Alle 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 he 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,
-he can proceed with the next request if any is pending
-
-@node libgnunetpeerinfo
-@subsection libgnunetpeerinfo
-
-@c %**end of header
-
-The PEERINFO API consists mainly of three different functionalities:
-maintaining a connection to the service, adding new information and retrieving
-information form the PEERINFO service.
-
-
-@menu
-* Connecting to the Service::
-* Adding Information::
-* Obtaining Information2::
-@end menu
-
-@node Connecting to the Service
-@subsubsection Connecting to the Service
-
-@c %**end of header
-
-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
-@subsubsection Adding Information
-
-@c %**end of header
-
-@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 Information2
-@subsubsection Obtaining Information2
-
-@c %**end of header
-
-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}.
-
-
-@node GNUnet's PEERSTORE subsystem
-@section GNUnet's PEERSTORE subsystem
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@node libgnunetpeerstore
-@subsection libgnunetpeerstore
-
-@c %**end of header
-
-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.
-
-@node GNUnet's SET Subsystem
-@section GNUnet's SET Subsystem
-
-@c %**end of header
-
-The SET service implements efficient set operations between two peers over a
-mesh 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
-
-@c %**end of header
-
-Sets created by a local client can be modified and reused for multiple
-operations. As each set operation requires potentially expensive special
-auxilliary data to be computed for each element of a set, a set can only
-participate in one type of set operation (i.e. 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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@node libgnunetset
-@subsection libgnunetset
-
-@c %**end of header
-
-@menu
-* Sets::
-* Listeners::
-* Operations::
-* Supplying a Set::
-* The Result Callback::
-@end menu
-
-@node Sets
-@subsubsection Sets
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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 callack 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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-To create symmetry between the two ways of starting a set operation (accepting
-and nitiating 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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-@menu
-* Creating Sets::
-* Listeners2::
-* Initiating Operations::
-* Modifying Sets::
-* Results and Operation Status::
-* Iterating Sets::
-@end menu
-
-@node Creating Sets
-@subsubsection Creating Sets
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-Each listener also requires a seperate 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 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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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@
-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
-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
-
-@c %**end of header
-
-In this phase, each peer transmits a Bloom filter over the remaining keys of
-the local set to the other peer using a
-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 his own set. If they do, he sends
-a@ GNUNET_MESSAGE_TYPE_SET_INTERSECTION_P2P_DONE back to indicate that the
-latest set is the final result. Otherwise, the receiver starts another Bloom
-fitler exchange, except this time as the sender.
-
-@node Salt
-@subsubsection Salt
-
-@c %**end of header
-
-Bloomfilter operations are probablistic: 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
-
-@c %**end of header
-
-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
-GNUNET_MESSAGE_TYPE_SET_RESULT and a status of 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 hasing them into
-buckets, such that future iterations have a fresh chance of succeeding if they
-failed due to collisions before.
-
-@node GNUnet's STATISTICS subsystem
-@section GNUnet's STATISTICS subsystem
-
-@c %**end of header
-
-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
-
-@node libgnunetstatistics
-@subsection libgnunetstatistics
-
-@c %**end of header
-
-@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 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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-@c %**end of header
-
-
-@menu
-* Statistics retrieval2::
-* Setting and updating statistics::
-* Watching for updates::
-@end menu
-
-@node Statistics retrieval2
-@subsubsection Statistics retrieval2
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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.
-
-@node GNUnet's Distributed Hash Table (DHT)
-@section GNUnet's Distributed Hash Table (DHT)
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-@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?
-
-@c %**end of header
-
-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.
-
-@node The API of libgnunetblock
-@subsubsection The API of libgnunetblock
-
-@c %**end of header
-
-The block library requires for each (family of) block type(s) a block plugin
-(implementing 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
-@c %**end of header
-
-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 parameterizes 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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-"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.
-
-@node libgnunetdht
-@subsection libgnunetdht
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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 %**end of header
-
-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
-
-@c %**end of header
-
-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 usefu only 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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-@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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-send after the original request, it is conceivalbe 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
-
-@c %**end of header
-
-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
-@c %**end of header
-
-
-@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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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 again
-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.
-Whenver 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.
-
-@node The GNU Name System (GNS)
-@section The GNU Name System (GNS)
-
-@c %**end of header
-
-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 ".gnu"
-or ".zkey".
-
-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.
-
-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::
-* Serving DNS lookups via GNS on W32::
-@end menu
-
-@node libgnunetgns
-@subsection libgnunetgns
-
-@c %**end of header
-
-The GNS API itself is extremely simple. Clients first connec 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
-
-@c %**end of header
-
-@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 (the ".gnu" zone). Note that a key must be provided, even if the
-name ends in ".zkey". This should typically be the public key of the
-master-zone of the user.
-@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 (possilby 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 cancelled.
-@item proc_cls The closure for proc.
-@end table
-
-@node Accessing the records
-@subsubsection Accessing the records
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-@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
-
-@c %**end of header
-
-@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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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 chaper 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: A query to
-an address ending in ".gnu" or ".zkey" is hijacked by @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
-
-@c %**end of header
-
-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 $VIRTUALDNS table2
-@end example
-
-Line 1 makes sure that all packets coming from a port our application opened
-beforehand (@code{$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.
-
-@node Serving DNS lookups via GNS on W32
-@subsection Serving DNS lookups via GNS on W32
-
-@c %**end of header
-
-This section documents how the libw32nsp (and gnunet-gns-helper-service-w32) do
-DNS resolutions of DNS queries on the local system. This only applies to GNUnet
-running on W32.
-
-W32 has a concept of "Namespaces" and "Namespace providers". These are used to
-present various name systems to applications in a generic way. Namespaces
-include DNS, mDNS, NLA and others. For each namespace any number of providers
-could be registered, and they are queried in an order of priority (which is
-adjustable).
-
-Applications can resolve names by using WSALookupService*() family of
-functions.
-
-However, these are WSA-only facilities. Common BSD socket functions for
-namespace resolutions are gethostbyname and getaddrinfo (among others). These
-functions are implemented internally (by default - by mswsock, which also
-implements the default DNS provider) as wrappers around WSALookupService*()
-functions (see "Sample Code for a Service Provider" on MSDN).
-
-On W32 GNUnet builds a libw32nsp - a namespace provider, which can then be
-installed into the system by using w32nsp-install (and uninstalled by
-w32nsp-uninstall), as described in "Installation Handbook".
-
-libw32nsp is very simple and has almost no dependencies. As a response to
-NSPLookupServiceBegin(), it only checks that the provider GUID passed to it by
-the caller matches GNUnet DNS Provider GUID, checks that name being resolved
-ends in ".gnu" or ".zkey", then connects to gnunet-gns-helper-service-w32 at
-127.0.0.1:5353 (hardcoded) and sends the name resolution request there,
-returning the connected socket to the caller.
-
-When the caller invokes NSPLookupServiceNext(), libw32nsp reads a completely
-formed reply from that socket, unmarshalls it, then gives it back to the
-caller.
-
-At the moment gnunet-gns-helper-service-w32 is implemented to ever give only
-one reply, and subsequent calls to NSPLookupServiceNext() will fail with
-WSA_NODATA (first call to NSPLookupServiceNext() might also fail if GNS failed
-to find the name, or there was an error connecting to it).
-
-gnunet-gns-helper-service-w32 does most of the processing:
-
-@itemize @bullet
-@item Maintains a connection to GNS.
-@item Reads GNS config and loads appropriate keys.
-@item Checks service GUID and decides on the type of record to look up,
-refusing to make a lookup outright when unsupported service GUID is passed.
-@item Launches the lookup
-@end itemize
-
-When lookup result arrives, gnunet-gns-helper-service-w32 forms a complete
-reply (including filling a WSAQUERYSETW structure and, possibly, a binary blob
-with a hostent structure for gethostbyname() client), marshalls it, and sends
-it back to libw32nsp. If no records were found, it sends an empty header.
-
-This works for most normal applications that use gethostbyname() or
-getaddrinfo() to resolve names, but fails to do anything with applications that
-use alternative means of resolving names (such as sending queries to a DNS
-server directly by themselves). This includes some of well known utilities,
-like "ping" and "nslookup".
-
-@node The GNS Namecache
-@section The GNS Namecache
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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 cancelled using
-@code{GNUNET_NAMECACHE_cancel}. Note that cancelling 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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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.
-
-@node The REVOCATION Subsystem
-@section The REVOCATION Subsystem
-@c %**end of header
-
-The REVOCATION subsystem is responsible for key revocation of Egos. If a user
-learns that his private key has been compromised or has lost it, he can use the
-REVOCATION system to inform all of the other users that this 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
-
-@c %**end of header
-
-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 his 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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-@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 cancelled using @code{GNUNET_REVOCATION_query_cancel} on the
-return value.
-
-@node Preparing revocations
-@subsubsection Preparing revocations
-
-@c %**end of header
-
-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 (i.e. proof of work incorrect), or otherwise
-indicates that the revocation has been processed successfully.
-
-@node The REVOCATION Peer-to-Peer Protocol
-@subsection The REVOCATION Peer-to-Peer Protocol
-
-@c %**end of header
-
-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.
-
-@node GNUnet's File-sharing (FS) Subsystem
-@section GNUnet's File-sharing (FS) Subsystem
-
-@c %**end of header
-
-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
-
-@node Encoding for Censorship-Resistant Sharing (ECRS)
-@subsection Encoding for Censorship-Resistant Sharing (ECRS)
-
-@c %**end of header
-
-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 %**end of header
-@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 provder'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
-
-@c %**end of header
-
-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.
-
-@table @asis
-@item Attachment Size
-@item  ecrs.pdf 270.68 KB
-@item https://gnunet.org/sites/default/files/ecrs.pdf
-@end table
-
-@node File-sharing persistence directory structure
-@subsection File-sharing persistence directory structure
-
-@c %**end of header
-
-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
-@cindex regex subsystem
-@node GNUnet's REGEX Subsystem
-@section GNUnet's REGEX Subsystem
-
-@c %**end of header
-
-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
-
-@c %**end of header
-
-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://gnunet.org/szengel2012ms, 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.
-Generally you can refer to the
-@file{contrib/regex_profiler_infiniband.conf} file in the sourcecode
-of GNUnet for an example configuration.
-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 AUTOSTART set of ARM:
-
-@example
-[regexprofiler]
-AUTOSTART = 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.
diff --git a/doc/chapters/installation.texi b/doc/chapters/installation.texi
deleted file mode 100644
index 63ab98e6d..000000000
--- a/doc/chapters/installation.texi
+++ /dev/null
@@ -1,3826 +0,0 @@
-@node GNUnet Installation Handbook
-@chapter GNUnet Installation Handbook
-
-This handbook describes how to install (build setup, compilation) and
-setup (configuration, start) GNUnet 0.10.x. After following these
-instructions you should be able to install and then start user-interfaces
-to interact with the network.
-
-This manual is far from complete, and we welcome informed contributions,
-be it in the form of new chapters or insightful comments.
-
-@menu
-* Dependencies::
-* Pre-installation notes::
-* Generic installation instructions::
-* Build instructions for Ubuntu 12.04 using Git::
-* Build Instructions for Microsoft Windows Platforms::
-* Build instructions for Debian 7.5::
-* Installing GNUnet from Git on Ubuntu 14.4::
-* Build instructions for Debian 8::
-* Outdated build instructions for previous revisions::
-* Portable GNUnet::
-* The graphical configuration interface::
-* How to start and stop a GNUnet peer::
-@end menu
-
-@node Dependencies
-@section Dependencies
-@c %**end of header
-
-This section lists the various known dependencies for
-GNUnet @value{EDITION}.
-Suggestions for missing dependencies or wrong version numbers are welcome.
-
-@menu
-* External dependencies::
-* Fixing libgnurl build issues::
-* Optional dependencies::
-* Internal dependencies::
-@end menu
-
-@node External dependencies
-@subsection External dependencies
-@c %**end of header
-
-These packages must be installed before a typical GNUnet installation
-can be performed:
-
-@itemize @bullet
-@item autoconf
-@item automake
-@item pkg-config
-@item libltdl
-@item gstreamer
-@item gst-plugins-base
-@item perl
-@item python (only 2.7 supported)@footnote{tests and gnunet-qr}
-@item jansson
-@item nss
-@item glib
-@item gmp
-@item bluez
-@item miniupnpc
-@item gettext
-@item which
-@item texinfo
-@item GNU libmicrohttpd @geq{} 0.9.30 @footnote{We recommend to build it
-with a GnuTLS version that was configured with libunbound ("DANE support")}
-@item GNU libextractor @geq{} 1.0
-@item GNU libtool @geq{} 2.2
-@item GNU libunistring @geq{} 0.9.1.1
-@item GNU libidn @geq{} 1.0.0
-@item @uref{https://gnupg.org/software/libgcrypt/, GNU libgcrypt} @geq{}
-@uref{https://gnupg.org/ftp/gcrypt/libgcrypt/, 1.6.0}
-@item @uref{https://gnutls.org/, GnuTLS} @geq{} 3.2.7
-@footnote{We recommend to compile with libunbound for DANE support;
-GnuTLS also requires GNU nettle 2.7 (update: GnuTLS 3.2.7 appears NOT
-to work against GNU nettle > 2.7, due to some API updatings done by
-nettle. Thus it should be compiled against nettle 2.7
-and, in case you get some error on the reference to `rpl_strerror' being
-undefined, follow the instructions on
-@uref{http://lists.gnupg.org/pipermail/gnutls-devel/2013-November/006588.html, this}
-post (and the link inside it)).}
-@item @uref{https://gnunet.org/gnurl, gnURL} libgnurl @geq{} 7.34.0
-@footnote{must be compiled after @code{GnuTLS}}
-@item libglpk @geq{} 4.45
-@item @uref{http://www.openssl.org/, OpenSSL} @geq{} 1.0
-@item TeX Live @geq{} 2012, optional (for gnunet-bcd)
-@item Texinfo @geq{} 5.2 (for documentation)
-@item libsqlite @geq{} 3.8.0 @footnote{(note that the code will
-compile and often work with lower version numbers, but you may get subtle
-bugs with respect to quota management in certain rare cases);
-alternatively, MySQL or Postgres can also be installed, but those
-databases will require more complex configurations (not
-recommended for first-time users)}
-@item zlib
-@end itemize
-
-@node Fixing libgnurl build issues
-@subsection Fixing libgnurl build issues
-
-If you have to compile libgnurl from source since the version included in
-your distribution is to old you perhaps get an error message while
-running the @file{configure} script:
-
-@example
-$ configure
-...
-checking for 64-bit curl_off_t data type... unknown
-checking for 32-bit curl_off_t data type... unknown
-checking for 16-bit curl_off_t data type... unknown
-configure: error: cannot find data type for curl_off_t.
-@end example
-
-@noindent
-Solution:
-
-Before running the configure script, set:
-
-@example
-CFLAGS="-I. -I$BUILD_ROOT/include"
-@end example
-
-@node Optional dependencies
-@subsection Optional dependencies
-
-These applications must be installed for various experimental or otherwise
-optional features such as @code{gnunet-conversation}, @code{gnunet-gtk}.
-
-@itemize @bullet
-@item libpulse 2.0 or higher, optional (for gnunet-conversation)
-@item libopus 1.0.1 or higher, optional (for gnunet-conversation)
-@item libogg 1.3.0 or higher, optional (for gnunet-conversation)
-@item certool (binary) optional @footnote{for convenient installation of
-the GNS proxy (available as part of Debian's libnss3-tools)}
-@item python-zbar 0.10 or higher, optional (for gnunet-qr)
-@item Gtk+ 3.0 or higher, optional (for gnunet-gtk)
-@item libgladeui must match Gtk+ version, optional (for gnunet-gtk)
-@item libqrencode 3.0 or higher, optional (for gnunet-namestore-gtk)
-@end itemize
-
-@node Internal dependencies
-@subsection 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 @code{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
-
-
-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
-
-
-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
-
-@node Pre-installation notes
-@section Pre-installation notes
-
-Please note that in the code instructions for the installation,
-@emph{#} indicates commands run as privileged root user and
-@emph{$} shows commands run as unprivileged ("normal") system user.
-
-
-@node Generic installation instructions
-@section Generic installation instructions
-
-First, in addition to the GNUnet sources you must download the latest version
-of various dependencies. 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, sqlite or Postgres). The following instructions will assume
-that you installed at least sqlite. For most distributions you should be able
-to find pre-build packages for the database. Again, make sure to install the
-client libraries and the respective development headers (if they are
-packaged separately) as well.
-
-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 are linked from the bottom of this page. Please consult
-them now. If your distribution is not listed, please study the 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.
-
-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 Debian and Ubuntu GNU/Linux, type:
-
-@example
-# adduser --system --home /var/lib/gnunet --group \
---disabled-password gnunet
-# addgroup --system gnunetdns
-@end example
-
-On other Unixes, this should have the same effect:
-
-@example
-# useradd --system --groups gnunet --home-dir /var/lib/gnunet
-# addgroup --system gnunetdns
-@end example
-
-Now compile and install GNUnet using:
-
-@example
-$ tar xvf gnunet-0.10.?.tar.gz
-$ cd gnunet-0.10.?
-$ ./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 @code{./configure} command.
-DEBUG-level log messages are in English-only and should only be useful for
-developers (or for filing really detailed bug reports). 
-
-Finally, you probably want to compile @code{gnunet-gtk}, which
-includes gnunet-setup (graphical tool for configuration)
-and @code{gnunet-fs-gtk} (graphical tool for file-sharing):
-
-@example
-$ tar xvf gnunet-gtk-0.10.?.tar.gz
-$ cd gnunet-gtk-0.10.?
-$ ./configure --with-gnunet=/usr/local/
-$ make
-$ sudo make install
-$ cd ..
-$ sudo ldconfig # just to be safe
-@end example
-
-Next, edit the file @file{/etc/gnunet.conf} to contain the following:
-
-@example
-[arm]
-SYSTEM_ONLY = YES
-USER_ONLY = NO
-@end example
-
-You may need to update your ld.so cache to include files installed in
-@file{/usr/local/lib}: @code{ # ldconfig }.
-
-Then, switch from user root to user 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 users @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
-
-This will only start the system-wide GNUnet services. Type exit to get back
-your root shell. Now, you need to configure the per-user part. For each
-$USER on the system, run: @code{ # adduser $USER gnunet }.
-
-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]
-SYSTEM_ONLY = NO
-USER_ONLY = YES
-DEFAULTSERVICES = gns
-@end example
-
-and start the per-user services using
-
-@code{@
- $ gnunet-arm -c ~/.config/gnunet.conf -s@
-}@
-
-Again, adding a @code{crontab} entry to autostart the peer is advised:@
-@code{@
-@@reboot /usr/local/bin/gnunet-arm -c $HOME/.config/gnunet.conf -s@
-}@
-
-Note that some GNUnet services (such as SOCKS5 proxies) may need a system-wide
-TCP port for each user. For those services, systems with more than one user may
-require each user to specify a different port number in their personal
-configuration file.
-
-Finally, the user should perform the basic initial setup for the GNU Name
-System. This is done by running two commands:@
-
-@example
-$ gnunet-gns-import.sh@
-$ gnunet-gns-proxy-setup-ca@
-@end example
-
-The first generates the default zones, wheras the second setups the GNS
-Certificate Authority with the user's browser. Now, to actiave 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
-
-
-The exact details may differ a bit, which is fine. Add the text
-@emph{"gns [NOTFOUND=return]"} after @emph{"files"}:
-
-@example
-hosts: files gns [NOTFOUND=return] mdns4_minimal [NOTFOUND=return] dns mdns4
-@end example
-
-
-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. 
-
-
-
-@node Build instructions for Ubuntu 12.04 using Git
-@section Build instructions for Ubuntu 12.04 using Git
-
-
-@menu
-* Install the required build tools::
-* Install libgcrypt 1.6 and libgpg-error::
-* Install gnutls with DANE support::
-* Install libgnurl::
-* Install libmicrohttpd from Git::
-* Install libextractor from Git::
-* Install GNUnet dependencies::
-* Build GNUnet::
-* Install the GNUnet-gtk user interface from Git::
-@end menu
-
-@node  Install the required build tools
-@subsection  Install the required build tools
-
-First, make sure Git is installed on your system:
-
-@example
-$ sudo apt-get install git
-@end example
-
-Install the essential buildtools:
-
-@example
-$ sudo apt-get install automake autopoint autoconf libtool
-@end example
-
-@node Install libgcrypt 1.6 and libgpg-error
-@subsection Install libgcrypt 1.6 and libgpg-error
-
-@example
-$ wget ftp://ftp.gnupg.org/gcrypt/libgpg-error/libgpg-error-1.12.tar.bz2
-$ tar xf libgpg-error-1.12.tar.bz2
-$ cd libgpg-error-1.12
-$ ./configure
-$ sudo make install ; cd ..
-@end example
-
-@node Install gnutls with DANE support
-@subsection Install gnutls with DANE support
-
-@example
-$ wget http://www.lysator.liu.se/~nisse/archive/nettle-2.7.1.tar.gz
-$ tar xf nettle-2.7.1.tar.gz
-$ cd nettle-2.7.1
-$ ./configure
-$ sudo make install ; cd ..
-@end example
-
-@example
-$ wget https://www.nlnetlabs.nl/downloads/ldns/ldns-1.6.16.tar.gz
-$ tar xf ldns-1.6.16.tar.gz
-$ cd ldns-1.6.16
-$ ./configure
-$ sudo make install ; cd ..
-@end example
-
-@example
-$ wget https://unbound.net/downloads/unbound-1.4.21.tar.gz
-$ tar xf unbound-1.4.21.tar.gz
-$ cd unbound-1.4.21
-$ ./configure
-$ sudo make install ; cd ..
-@end example
-
-@example
-$ wget ftp://ftp.gnutls.org/gcrypt/gnutls/v3.1/gnutls-3.1.17.tar.xz
-$ tar xf gnutls-3.1.17.tar.xz
-$ cd gnutls-3.1.17
-$ ./configure
-$ sudo make install ; cd ..
-@end example
-
-@example
-$ wget ftp://ftp.gnupg.org/gcrypt/libgcrypt/libgcrypt-1.6.0.tar.bz2
-$ tar xf libgcrypt-1.6.0.tar.bz2
-$ cd libgcrypt-1.6.0
-$ ./configure
-$ sudo make install ; cd ..
-@end example
-
-@node Install libgnurl
-@subsection Install libgnurl
-
-@example
-$ wget https://gnunet.org/sites/default/files/gnurl-7.34.0.tar.bz2
-$ tar xf gnurl-7.34.0.tar.bz2
-$ cd gnurl-7.34.0
-$ ./configure --enable-ipv6 --with-gnutls --without-libssh2 \
-  --without-libmetalink --without-winidn --without-librtmp \
-  --without-nghttp2 --without-nss --without-cyassl \
-  --without-polarssl --without-ssl --without-winssl \
-  --without-darwinssl --disable-sspi --disable-ntlm-wb \
-  --disable-ldap --disable-rtsp --disable-dict --disable-telnet \
-  --disable-tftp --disable-pop3 --disable-imap --disable-smtp \
-  --disable-gopher --disable-file --disable-ftp
-$ sudo make install ; cd ..
-@end example
-
-@node Install libmicrohttpd from Git
-@subsection Install libmicrohttpd from Git
-
-@example
-$ git clone https://gnunet.org/git/libmicrohttpd
-$ cd libmicrohttpd/
-$ ./bootstrap
-$ ./configure
-$ sudo make install ; cd ..
-@end example
-
-@node  Install libextractor from Git
-@subsection  Install libextractor from Git
-
-Install libextractor dependencies:
-
-@example
-$ sudo apt-get install zlib1g-dev libgsf-1-dev libmpeg2-4-dev \
- libpoppler-dev libvorbis-dev libexiv2-dev libjpeg-dev \
- libtiff-dev libgif-dev libvorbis-dev libflac-dev libsmf-dev \
- g++
-@end example
-
-Build libextractor:
-
-@example
-$ git clone https://gnunet.org/git/libextractor
-$ cd libextractor
-$ ./bootstrap
-$ ./configure
-$ sudo make install ; cd ..
-@end example
-
-@node Install GNUnet dependencies
-@subsection Install GNUnet dependencies
-
-@example
-$ sudo apt-get install libidn11-dev libunistring-dev libglpk-dev \
- libpulse-dev libbluetooth-dev libsqlite-dev
-@end example
-
-Install libopus:
-
-@example
-$ wget http://downloads.xiph.org/releases/opus/opus-1.1.tar.gz
-$ tar xf opus-1.1.tar.gz
-$ cd opus-1.1/
-$ ./configure
-$ sudo make install ; cd ..
-@end example
-
-Choose one or more database backends:
-
-SQLite3:
-@example
-$ sudo apt-get install libsqlite3-dev
-@end example
-MySQL:
-@example
-$ sudo apt-get install libmysqlclient-dev
-@end example
-PostgreSQL:
-@example
-$ sudo apt-get install libpq-dev postgresql
-@end example
-
-
-
-@node Build GNUnet
-@subsection Build GNUnet
-
-
-
-@menu
-* Configuring the installation path::
-* Configuring the system::
-* Installing components requiring sudo permission::
-* Build::
-@end menu
-
-@node Configuring the installation path
-@subsubsection Configuring the installation path
-
-You can specify the location of the GNUnet installation by setting the prefix
-when calling the configure script with @code{--prefix=DIRECTORY}
-
-@example
-$ export PATH=$PATH:DIRECTORY/bin
-@end example
-
-@node Configuring the system
-@subsubsection Configuring the system
-
-Please make sure NOW that you have created a user and group 'gnunet'
-and additionally a group 'gnunetdns':
-
-@example
-$ sudo addgroup gnunet
-$ sudo addgroup gnunetdns
-$ sudo adduser gnunet
-@end example
-
-Each GNUnet user should be added to the 'gnunet' group (may
-require fresh login to come into effect):
-
-@example
-$ sudo useradd -G  gnunet
-@end example
-
-@node Installing components requiring sudo permission
-@subsubsection Installing components requiring sudo permission
-
-Some components, like the nss plugin required for GNS, may require root
-permissions. To allow these few components to be installed use:
-
-@example
-$ ./configure --with-sudo
-@end example
-
-@node Build
-@subsubsection Build
-
-@example
-$ git clone https://gnunet.org/git/gnunet/
-$ cd gnunet/
-$ ./bootstrap
-@end example
-
-Use the required configure call including the optional installation prefix
-PREFIX or the sudo permissions:
-
-@example
-$ ./configure [ --with-sudo | --with-prefix=PREFIX ]
-@end example
-
-@example
-$ make; sudo make install
-@end example
-
-After installing it, you need to create an empty configuration file:
-
-@example
-mkdir ~/.gnunet; touch ~/.gnunet/gnunet.conf
-@end example
-
-And finally you can start GNUnet with @code{$ gnunet-arm -s}.
-
-@node Install the GNUnet-gtk user interface from Git
-@subsection Install the GNUnet-gtk user interface from Git
-
-
-Install depencies:
-
-@example
-$ sudo apt-get install libgtk-3-dev libunique-3.0-dev libgladeui-dev \
-libqrencode-dev
-@end example
-
-To build GNUnet (with an optional prefix)and execute:
-
-@example
-$ git clone https://gnunet.org/git/gnunet-gtk/
-$ cd gnunet-gtk/
-$ ./bootstrap
-$ ./configure [--prefix=PREFIX] --with-gnunet=DIRECTORY
-$ make; sudo make install
-@end example
-
-@node Build Instructions for Microsoft Windows Platforms
-@section Build Instructions for Microsoft Windows Platforms
-
-@menu
-* Introduction to building on MS Windows::
-* Requirements::
-* Dependencies & Initial Setup::
-* GNUnet Installation::
-* Adjusting Windows for running and testing GNUnet::
-* Building the GNUnet Installer::
-* Using GNUnet with Netbeans on Windows::
-@end menu
-
-@node Introduction to building on MS Windows
-@subsection Introduction to building on MS Windows
-
-
-This document is a guide to building GNUnet and its dependencies on Windows
-platforms. GNUnet development is mostly done under Linux and especially SVN
-checkouts may not build out of the box. We regret any inconvenience, and
-if you have problems, please report them.
-
-@node Requirements
-@subsection Requirements
-
-The Howto is based upon a @strong{Windows Server 2008 32bit@strong{
-Installation, @strong{sbuild} and thus a @uref{http://www.mingw.org/wiki/MSYS,
-MSYS+MinGW} (W32-GCC-Compiler-Suite + Unix-like Userland) installation. sbuild
-is a convenient set of scripts which creates a working msys/mingw installation
-and installs most dependencies required for GNUnet. }}
-
-As of the point of the creation of this Howto, GNUnet @strong{requires} a
-Windows @strong{Server} 2003 or newer for full feature support. Windows Vista
-and later will also work, but
-@strong{non-server version can not run a VPN-Exit-Node} as the NAT features
-have been removed as of Windows Vista.
-
-@node Dependencies & Initial Setup
-@subsection Dependencies & Initial Setup
-
-
-@itemize @bullet
-
-@item
-Install a fresh version of @strong{Python 2.x}, even if you are using a x64-OS,
-install a 32-bit version for use with sbuild. Python 3.0 currently is
-incompatible.
-
-@item
-Install your favorite @uref{http://code.google.com/p/tortoisegit/, GIT} &
-@uref{http://tortoisesvn.net/, SVN}-clients.
-
-@item
-You will also need some archive-manager like @uref{http://www.7-zip.org/, 7zip}.
-
-@item
-Pull a copy of sbuild to a directory of your choice, which will be used in the
-remainder of this guide. For now, we will use @file{c:\gnunet\sbuild\}
-
-@item
-in @file{sbuild\src\mingw\mingw32-buildall.sh}, comment out the packages
-@strong{gnunet-svn} and @strong{gnunet-gtk-svn}, as we don't want sbuild to
-compile/install those for us.
-
-@item
-Follow LRN's sbuild installation instructions.-
-@end itemize
-
-Please note that sbuild may (or will most likely) fail during installation,
-thus you really HAVE to @strong{check the logfiles} created during the
-installation process. Certain packages may fail to build initially due to
-missing dependencies, thus you may have to
-@strong{substitute those with binary-versions initially}. Later on once
-dependencies are satisfied you can re-build the newer package versions.
-
-@strong{It is normal that you may have to repeat this step multiple times and
-there is no uniform way to fix all compile-time issues, as the build-process
-of many of the dependencies installed are rather unstable on win32 and certain
-releases may not even compile at all.}
-
-Most dependencies for GNUnet have been set up by sbuild, thus we now should add
-the @file{bin/} directories in your new msys and mingw installations to PATH.
-You will want to create a backup of your finished msys-environment by now.
-
-@node GNUnet Installation
-@subsection GNUnet Installation
-
-First, we need to launch our msys-shell, you can do this via
-
-@file{C:\gnunet\sbuild\msys\msys.bat}
-
-You might wish to take a look at this file and adjust some login-parameters to
-your msys environment.
-
-Also, sbuild added two pointpoints to your msys-environment, though those
-might remain invisible:
-
-@itemize @bullet
-
-@item
-/mingw, which will mount your mingw-directory from sbuild/mingw and the other one is
-
-@item
-/src which contains all the installation sources sbuild just compiled.
-@end itemize
-
-Check out the current gnunet-sources (svn-head) from the gnunet-repository,
-we will do this in your home directory:
-
-@code{svn checkout https://gnunet.org/svn/gnunet/ ~/gnunet}
-
-Now, we will first need to bootstrap the checked out installation and then
-configure it accordingly.
-
-@example
-cd ~/gnunet
-./bootstrap
-STRIP=true CPPFLAGS="-DUSE_IPV6=1 -DW32_VEH" CFLAGS="$CFLAGS -g -O2" \
-./configure --prefix=/ --docdir=/share/doc/gnunet \
---with-libiconv-prefix=/mingw --with-libintl-prefix=/mingw \
---with-libcurl=/mingw --with-extractor=/mingw --with-sqlite=/mingw \
---with-microhttpd=/mingw --with-plibc=/mingw --enable-benchmarks \
---enable-expensivetests --enable-experimental --with-qrencode=/mingw \
---enable-silent-rules --enable-experimental 2>&1 | tee -a ./configure.log
-@end example
-
-The parameters above will configure for a reasonable gnunet installation to the
-your msys-root directory. Depending on which features your would like to build
-or you may need to specify additional dependencies. Sbuild installed most libs
-into the /mingw subdirectory, so remember to prefix library locations with
-this path.
-
-Like on a unixoid system, you might want to use your home directory as prefix
-for your own gnunet installation for development, without tainting the
-buildenvironment. Just change the "prefix" parameter to point towards
-~/ in this case.
-
-Now it's time to compile gnunet as usual. Though this will take some time, so
-you may fetch yourself a coffee or some Mate now...
-
-@example
-make ; make install
-@end example
-
-@node Adjusting Windows for running and testing GNUnet
-@subsection Adjusting Windows for running and testing GNUnet
-
-Assuming the build succeeded and you
-@strong{added the bin directory of your gnunet to PATH}, you can now use your
-gnunet-installation as usual. Remember that UAC or the windows firewall may
-popup initially, blocking further execution of gnunet until you acknowledge
-them (duh!).
-
-You will also have to take the usual steps to get p2p software running properly
-(port forwarding, ...), and gnunet will require administrative permissions as
-it may even install a device-driver (in case you are using gnunet-vpn and/or
-gnunet-exit).
-
-@node Building the GNUnet Installer
-@subsection Building the GNUnet Installer
-
-The GNUnet installer is made with @uref{http://nsis.sourceforge.net/, NSIS}
-The installer script is located in @file{contrib\win} in the
-GNUnet source tree.
-
-@node Using GNUnet with Netbeans on Windows
-@subsection Using GNUnet with Netbeans on Windows
-
-TODO
-
-@node Build instructions for Debian 7.5
-@section Build instructions for Debian 7.5
-
-
-These are the installation instructions for Debian 7.5. They were tested using
-a minimal, fresh Debian 7.5 AMD64 installation without non-free software
-(no contrib or non-free). By "minimal", we mean that during installation, we
-did not select any desktop environment, servers or system utilities during the
-"tasksel" step. Note that the packages and the dependencies that we will
-install during this chapter take about 1.5 GB of disk space. Combined with
-GNUnet and space for objects during compilation, you should not even attempt
-this unless you have about 2.5 GB free after the minimal Debian installation.
-Using these instructions to build a VM image is likely to require a minimum of
-4-5 GB for the VM (as you will likely also want a desktop manager).
-
-GNUnet's security model assumes that your @file{/home} directory is encrypted.
-Thus, if possible, you should encrypt your home partition
-(or per-user home directory).
-
-Naturally, the exact details of the starting state for your installation
-should not matter much. For example, if you selected any of those installation
-groups you might simply already have some of the necessary packages installed.
-We did this for testing, as this way we are less likely to forget to mention a
-required package. Note that we will not install a desktop environment, but of
-course you will need to install one to use GNUnet's graphical user interfaces.
-Thus, it is suggested that you simply install the desktop environment of your
-choice before beginning with the instructions.
-
-
-
-@menu
-* Update::
-* Stable? Hah!::
-* Update again::
-* Installing packages::
-* Installing dependencies from source::
-* Installing GNUnet from source::
-* But wait there is more!::
-@end menu
-
-@node Update
-@subsection Update
-
-After any installation, you should begin by running
-
-@example
-# apt-get update ; apt-get upgrade
-@end example
-
-to ensure that all of your packages are up-to-date. Note that the "#" is used
-to indicate that you need to type in this command as "root"
-(or prefix with "sudo"), whereas "$" is used to indicate typing in a command
-as a normal user.
-
-@node Stable? Hah!
-@subsection Stable? Hah!
-
-Yes, we said we start with a Debian 7.5 "stable" system. However, to reduce the
-amount of compilation by hand, we will begin by allowing the installation of
-packages from the testing and unstable distributions as well. We will stick to
-"stable" packages where possible, but some packages will be taken from the
-other distributions. Start by modifying @file{/etc/apt/sources.list} to contain
-the following (possibly adjusted to point to your mirror of choice):
-@example
-# These were there before:
-deb http://ftp.de.debian.org/debian/ wheezy main
-deb-src http://ftp.de.debian.org/debian/ wheezy main
-deb http://security.debian.org/ wheezy/updates main
-deb-src http://security.debian.org/ wheezy/updates main
-deb http://ftp.de.debian.org/debian/ wheezy-updates main
-deb-src http://ftp.de.debian.org/debian/ wheezy-updates main
-
-# Add these lines (feel free to adjust the mirror):
-deb http://ftp.de.debian.org/debian/ testing main
-deb http://ftp.de.debian.org/debian/ unstable main
-@end example
-
-The next step is to create/edit your @file{/etc/apt/preferences} file to look
-like this:
-
-@example
-Package: *
-Pin: release a=stable,n=wheezy
-Pin-Priority: 700
-
-Package: *
-Pin: release o=Debian,a=testing
-Pin-Priority: 650
-
-Package: *
-Pin: release o=Debian,a=unstable
-Pin-Priority: 600
-@end example
-
-You can read more about Apt Preferences here and here. Note that other pinnings
-are likely to also work for GNUnet, the key thing is that you need some
-packages from unstable (as shown below). However, as unstable is unlikely to
-be comprehensive (missing packages) or might be problematic (crashing packages),
-you probably want others from stable and/or testing.
-
-@node Update again
-@subsection Update again
-
-Now, run again@
-
-@example
-# apt-get update@
-# apt-get upgrade@
-@end example
-
-to ensure that all your new distribution indices are downloaded, and that your
-pinning is correct: the upgrade step should cause no changes at all.
-
-@node Installing packages
-@subsection Installing packages
-
-We begin by installing a few Debian packages from stable:@
-
-@example
-# apt-get install gcc make python-zbar libltdl-dev libsqlite3-dev \
-  libunistring-dev libopus-dev libpulse-dev openssl libglpk-dev \
-  texlive libidn11-dev libmysqlclient-dev libpq-dev libarchive-dev \
-  libbz2-dev libexiv2-dev libflac-dev libgif-dev libglib2.0-dev \
-  libgtk-3-dev libmagic-dev libjpeg8-dev libmpeg2-4-dev libmp4v2-dev \
-  librpm-dev libsmf-dev libtidy-dev libtiff5-dev libvorbis-dev \
-  libogg-dev zlib1g-dev g++ gettext libgsf-1-dev libunbound-dev \
-  libqrencode-dev libgladeui-dev nasm texlive-latex-extra \
-  libunique-3.0-dev gawk miniupnpc libfuse-dev libbluetooth-dev
-@end example
-
-After that, we install a few more packages from unstable:@
-
-@example
-# apt-get install -t unstable nettle-dev libgstreamer1.0-dev \
-  gstreamer1.0-plugins-base gstreamer1.0-plugins-good \
-  libgstreamer-plugins-base1.0-dev
-@end example
-
-@node Installing dependencies from source
-@subsection Installing dependencies from source
-
-Next, we need to install a few dependencies from source. You might want to do
-this as a "normal" user and only run the @code{make install} steps as root
-(hence the @code{sudo} in the commands below). Also, you do this from any
-directory. We begin by downloading all dependencies, then extracting the
-sources, and finally compiling and installing the libraries:@
-
-@example
-$ wget https://libav.org/releases/libav-9.10.tar.xz
-$ wget http://ftp.gnu.org/gnu/libextractor/libextractor-1.3.tar.gz
-$ wget ftp://ftp.gnupg.org/gcrypt/libgpg-error/libgpg-error-1.12.tar.bz2
-$ wget ftp://ftp.gnupg.org/gcrypt/libgcrypt/libgcrypt-1.6.0.tar.bz2
-$ wget ftp://ftp.gnutls.org/gcrypt/gnutls/v3.2/gnutls-3.2.7.tar.xz
-$ wget http://ftp.gnu.org/gnu/libmicrohttpd/libmicrohttpd-0.9.33.tar.gz
-$ wget https://gnunet.org/sites/default/files/gnurl-7.34.0.tar.bz2
-$ tar xvf libextractor-1.3.tar.gz
-$ tar xvf libgpg-error-1.12.tar.bz2
-$ tar xvf libgcrypt-1.6.0.tar.bz2
-$ tar xvf gnutls-3.2.7.tar.xz
-$ tar xvf libmicrohttpd-0.9.33.tar.gz
-$ tar xvf gnurl-7.34.0.tar.bz2
-$ cd libav-0.9 ; ./configure --enable-shared;
-$ make; sudo make install; cd ..
-$ cd libextractor-1.3 ; ./configure;
-$ make ; sudo make install; cd ..
-$ cd libgpg-error-1.12; ./configure;
-$ make ; sudo make install; cd ..
-$ cd libgcrypt-1.6.0; ./configure --with-gpg-error-prefix=/usr/local;
-$ make ; sudo make install ; cd ..
-$ cd gnutls-3.2.7 ; ./configure;
-$ make ; sudo make install ; cd ..
-$ cd libmicrohttpd-0.9.33; ./configure;
-$ make ; sudo make install ; cd ..
-$ cd gnurl-7.34.0
-$ ./configure --enable-ipv6 --with-gnutls=/usr/local --without-libssh2 \
- --without-libmetalink --without-winidn --without-librtmp --without-nghttp2 \
- --without-nss --without-cyassl --without-polarssl --without-ssl \
- --without-winssl --without-darwinssl --disable-sspi --disable-ntlm-wb \
- --disable-ldap --disable-rtsp --disable-dict --disable-telnet --disable-tftp \
- --disable-pop3 --disable-imap --disable-smtp --disable-gopher --disable-file \
- --disable-ftp
-$ make ; sudo make install; cd ..
-@end example
-
-@node Installing GNUnet from source
-@subsection Installing GNUnet from source
-
-
-For this, simply follow the generic installation instructions from
-here.
-
-@node But wait there is more!
-@subsection But wait there is more!
-
-So far, we installed all of the packages and dependencies required to ensure
-that all of GNUnet would be built. However, while for example the plugins to
-interact with the MySQL or Postgres databases have been created, we did not
-actually install or configure those databases. Thus, you will need to install
-and configure those databases or stick with the default Sqlite database.
-Sqlite is usually fine for most applications, but MySQL can offer better
-performance and Postgres better resillience.
-
-
-@node Installing GNUnet from Git on Ubuntu 14.4
-@section Installing GNUnet from Git on Ubuntu 14.4
-
-@strong{Install the required build tools:}
-@code{ $ sudo apt-get install git automake autopoint autoconf }
-
-@strong{Install the required dependencies}
-@example
-$ sudo apt-get install libltdl-dev libgpg-error-dev libidn11-dev \
- libunistring-dev libglpk-dev libbluetooth-dev libextractor-dev \
- libmicrohttpd-dev libgnutls28-dev
-@end example
-
-@strong{Choose one or more database backends}
-
-SQLite3:
-@example
-$ sudo apt-get install libsqlite3-dev
-@end example
-MySQL:
-@example
-$ sudo apt-get install libmysqlclient-dev
-@end example
-PostgreSQL:
-@example
-$ sudo apt-get install libpq-dev postgresql
-@end example
-
-@strong{Install the optional dependencies for gnunet-conversation:}
-
-@example
-$ sudo apt-get install gstreamer1.0 libpulse-dev libopus-dev
-@end example
-
-@strong{Install the libgrypt 1.6.1:}
-For Ubuntu 14.04:
-@example
-$ sudo apt-get install libgcrypt20-dev
-@end example
-For Ubuntu older 14.04:
-@example
-$ wget ftp://ftp.gnupg.org/gcrypt/libgcrypt/libgcrypt-1.6.1.tar.bz2
-$ tar xf libgcrypt-1.6.1.tar.bz2
-$ cd libgcrypt-1.6.1
-$ ./configure
-$ sudo make install
-$ cd ..
-@end example
-@strong{Install libgnurl}
-@example
-$ wget https://gnunet.org/sites/default/files/gnurl-7.35.0.tar.bz2
-$ tar xf gnurl-7.35.0.tar.bz2
-$ cd gnurl-7.35.0
-$ ./configure --enable-ipv6 --with-gnutls --without-libssh2 \
- --without-libmetalink --without-winidn --without-librtmp --without-nghttp2 \
- --without-nss --without-cyassl --without-polarssl --without-ssl \
- --without-winssl --without-darwinssl --disable-sspi --disable-ntlm-wb \
- --disable-ldap --disable-rtsp --disable-dict --disable-telnet --disable-tftp \
- --disable-pop3 --disable-imap --disable-smtp --disable-gopher --disable-file \
- --disable-ftp
-$ sudo make install
-$ cd ..
-@end example
-
-@strong{Install GNUnet}
-@example
-$ git clone https://gnunet.org/git/gnunet/
-$ cd gnunet/
-$ ./bootstrap
-@end example
-
-If you want to:
-@itemize @bullet
-
-
-@item
-Install to a different directory:@
- --prefix=PREFIX
-
-@item
-Have sudo permission, but do not want to compile as root:@
- --with-sudo
-
-@item
-Want debug message enabled:@
- -- enable-logging=verbose
-@end itemize
-
-
-@code{@
- $ ./configure [ --with-sudo | --prefix=PREFIX | --- enable-logging=verbose]@
- $ make; sudo make install@
-}
-
-After installing it, you need to create an empty configuration file:@
-@code{touch ~/.config/gnunet.conf}
-
-And finally you can start GNUnet with@
-@code{$ gnunet-arm -s}
-
-@node Build instructions for Debian 8
-@section Build instructions for Debian 8
-
-These are the installation instructions for Debian 8. They were tested using a
-fresh Debian 8 AMD64 installation without non-free software (no contrib or
-non-free). During installation, I only selected "lxde" for the desktop
-environment. Note that the packages and the dependencies that we will install
-during this chapter take about 1.5 GB of disk space. Combined with GNUnet and
-space for objects during compilation, you should not even attempt this unless
-you have about 2.5 GB free after the Debian installation. Using these
-instructions to build a VM image is likely to require a minimum of 4-5 GB for
-the VM (as you will likely also want a desktop manager).
-
-GNUnet's security model assumes that your @code{/home} directory is encrypted.
-Thus, if possible, you should encrypt your entire disk, or at least just your
-home partition (or per-user home directory).
-
-Naturally, the exact details of the starting state for your installation should
-not matter much. For example, if you selected any of those installation groups
-you might simply already have some of the necessary packages installed. Thus,
-it is suggested that you simply install the desktop environment of your choice
-before beginning with the instructions.
-
-
-@menu
-* Update Debian::
-* Installing Debian Packages::
-* Installing Dependencies from Source2::
-* Installing GNUnet from Source2::
-* But wait (again) there is more!::
-@end menu
-
-@node Update Debian
-@subsection Update Debian
-
-After any installation, you should begin by running@
-@code{@
- # apt-get update@
- # apt-get upgrade@
-}@
-to ensure that all of your packages are up-to-date. Note that the "#" is used
-to indicate that you need to type in this command as "root" (or prefix with
-"sudo"), whereas "$" is used to indicate typing in a command as a normal
-user.
-
-@node Installing Debian Packages
-@subsection Installing Debian Packages
-
-We begin by installing a few Debian packages from stable:@
-@example
- # apt-get install gcc make python-zbar libltdl-dev libsqlite3-dev \ 
-  libunistring-dev libopus-dev libpulse-dev openssl libglpk-dev texlive \
-  libidn11-dev libmysqlclient-dev libpq-dev libarchive-dev libbz2-dev \
-  libflac-dev libgif-dev libglib2.0-dev libgtk-3-dev libmpeg2-4-dev \
-  libtidy-dev libvorbis-dev libogg-dev zlib1g-dev g++ gettext libgsf-1-dev \
-  libunbound-dev libqrencode-dev libgladeui-dev nasm texlive-latex-extra \
-  libunique-3.0-dev gawk miniupnpc libfuse-dev libbluetooth-dev \
-  gstreamer1.0-plugins-base gstreamer1.0-plugins-good \
-  libgstreamer-plugins-base1.0-dev nettle-dev libextractor-dev libgcrypt20-dev \
-  libmicrohttpd-dev
-@end example
-
-@node Installing Dependencies from Source2
-@subsection Installing Dependencies from Source2
-
-Yes, we said we start with a Debian 8 "stable" system, but because Debian
-linked GnuTLS without support for DANE, we need to compile a few things, in
-addition to GNUnet, still by hand. Yes, you can run GNUnet using the respective
-Debian packages, but then you will not get DANE support.
-
-Next, we need to install a few dependencies from source. You might want to do
-this as a "normal" user and only run the @code{make install} steps as root
-(hence the @code{sudo} in the commands below). Also, you do this from any
-directory. We begin by downloading all dependencies, then extracting the
-sources, and finally compiling and installing the libraries:@
-
-@code{@
- $ wget ftp://ftp.gnutls.org/gcrypt/gnutls/v3.3/gnutls-3.3.12.tar.xz@
- $ wget https://gnunet.org/sites/default/files/gnurl-7.40.0.tar.bz2@
- $ tar xvf gnutls-3.3.12.tar.xz@
- $ tar xvf gnurl-7.40.0.tar.bz2@
- $ cd gnutls-3.3.12 ; ./configure ; make ; sudo make install ; cd ..@
- $ cd gnurl-7.40.0@
- $ ./configure --enable-ipv6 --with-gnutls=/usr/local --without-libssh2 \
- --without-libmetalink --without-winidn --without-librtmp --without-nghttp2 \
- --without-nss --without-cyassl --without-polarssl --without-ssl \
- --without-winssl --without-darwinssl --disable-sspi --disable-ntlm-wb \
- --disable-ldap --disable-rtsp --disable-dict --disable-telnet --disable-tftp \
- --disable-pop3 --disable-imap --disable-smtp --disable-gopher --disable-file \
- --disable-ftp --disable-smb
- $ make ; sudo make install; cd ..@
-}
-
-@node Installing GNUnet from Source2
-@subsection Installing GNUnet from Source2
-
-For this, simply follow the generic installation instructions from@
-here.
-
-@node But wait (again) there is more!
-@subsection But wait (again) there is more!
-
-So far, we installed all of the packages and dependencies required to ensure
-that all of GNUnet would be built. However, while for example the plugins to
-interact with the MySQL or Postgres databases have been created, we did not
-actually install or configure those databases. Thus, you will need to install
-and configure those databases or stick with the default Sqlite database. Sqlite
-is usually fine for most applications, but MySQL can offer better performance
-and Postgres better resillience.
-
-@node Outdated build instructions for previous revisions
-@section Outdated build instructions for previous revisions
-
-This chapter contains a collection of outdated, older installation guides. They
-are mostly intended to serve as a starting point for writing up-to-date
-instructions and should not be expected to work for GNUnet 0.10.x.
-A set of older installation instructions can also be found in the
-@file{doc/outdated-and-old-installation-instructions.txt} in the source
-of GNUnet. This file covers old instructions which no longer receive
-security updates or any kind of support.
-
-
-@menu
-* Installing GNUnet 0.10.1 on Ubuntu 14.04::
-* Building GLPK for MinGW::
-* GUI build instructions for Ubuntu 12.04 using Subversion::
-* Installation with gnunet-update::
-* Instructions for Microsoft Windows Platforms (Old)::
-@end menu
-
-
-@node Installing GNUnet 0.10.1 on Ubuntu 14.04
-@subsection Installing GNUnet 0.10.1 on Ubuntu 14.04
-
-Install the required dependencies@
-
-@example
-$ sudo apt-get install libltdl-dev libgpg-error-dev libidn11-dev \
-  libunistring-dev libglpk-dev libbluetooth-dev libextractor-dev \
-  libmicrohttpd-dev libgnutls28-dev
-@end example
-
-Choose one or more database backends@
-SQLite3@
-@code{@
- $ sudo apt-get install libsqlite3-dev@
-}@
-MySQL@
-@code{@
- $ sudo apt-get install libmysqlclient-dev@
-}@
-PostgreSQL@
-@code{@
- $ sudo apt-get install libpq-dev postgresql@
-}
-
-Install the optional dependencies for gnunet-conversation:@
-@code{@
- $ sudo apt-get install gstreamer1.0 libpulse-dev libopus-dev@
-}
-
-Install the libgrypt 1.6:@
-For Ubuntu 14.04:@
-@code{$ sudo apt-get install libgcrypt20-dev}@
-For Ubuntu older 14.04:@
-@code{$ wget ftp://ftp.gnupg.org/gcrypt/libgcrypt/libgcrypt-1.6.1.tar.bz2@
- $ tar xf libgcrypt-1.6.1.tar.bz2@
- $ cd libgcrypt-1.6.1@
- $ ./configure@
- $ sudo make install@
- $ cd ..}
-
-Install libgnurl@
-@example
- $ wget https://gnunet.org/sites/default/files/gnurl-7.35.0.tar.bz2@
- $ tar xf gnurl-7.35.0.tar.bz2@
- $ cd gnurl-7.35.0@
- $ ./configure --enable-ipv6 --with-gnutls --without-libssh2 \
- --without-libmetalink --without-winidn --without-librtmp --without-nghttp2 \
- --without-nss --without-cyassl --without-polarssl --without-ssl \
- --without-winssl --without-darwinssl --disable-sspi --disable-ntlm-wb \
- --disable-ldap --disable-rtsp --disable-dict --disable-telnet --disable-tftp \
- --disable-pop3 --disable-imap --disable-smtp --disable-gopher --disable-file \
- --disable-ftp@
- $ sudo make install@
- $ cd ..@
-@end example
-
-Install GNUnet@
-@code{@
- $ wget http://ftpmirror.gnu.org/gnunet/gnunet-0.10.1.tar.gz@
- $ tar xf gnunet-0.10.1.tar.gz@
- $ cd gnunet-0.10.1@
-}
-
-If you want to:
-@itemize @bullet
-
-@item
-Install to a different directory:@
- --prefix=PREFIX
-
-@item
-Have sudo permission, but do not want to compile as root:@
- --with-sudo
-
-@item
-Want debug message enabled:@
- -- enable-logging=verbose
-@end itemize
-
-@code{@
- $ ./configure [ --with-sudo | --prefix=PREFIX | --enable-logging=verbose]@
- $ make; sudo make install@
-}
-
-After installing it, you need to create an empty configuration file:@
-@code{touch ~/.config/gnunet.conf}
-
-And finally you can start GNUnet with@
-@code{$ gnunet-arm -s}
-
-@node Building GLPK for MinGW
-@subsection Building GLPK for MinGW
-
-GNUnet now requires the GNU Linear Programming Kit (GLPK). Since there's is no
-package you can install with @code{mingw-get} you have to compile it from
-source:
-
-@itemize @bullet
-
-@item
-Download the latest version from http://ftp.gnu.org/gnu/glpk/ 
-
-@item
-Unzip it using your favourite unzipper@
-In the MSYS shell: 
-
-@item
-change to the respective directory 
-
-@item
-@code{./configure '--build=i686-pc-mingw32'}
-
-@item
-run @code{make install check }
-
-MinGW does not automatically detect the correct buildtype so you have to
-specify it manually
-@end itemize
-
-
-@node GUI build instructions for Ubuntu 12.04 using Subversion
-@subsection GUI build instructions for Ubuntu 12.04 using Subversion
-
-After installing GNUnet you can continue installing the GNUnet GUI tools:
-
-First, install the required dependencies:
-
-@code{@
- $ sudo apt-get install libgladeui-dev libqrencode-dev@
-}
-
-Please ensure that the GNUnet shared libraries can be found by the linker. If
-you installed GNUnet libraries in a non standard path (say
-GNUNET_PREFIX=/usr/local/lib/), you can
-@itemize @bullet
-
-
-@item
-set the environmental variable permanently to@
-@code{LD_LIBRARY_PATH=$GNUNET_PREFIX}
-
-@item
-or add @code{$GNUNET_PREFIX} to @code{/etc/ld.so.conf}
-@end itemize
-
-
-Now you can checkout and compile the GNUnet GUI tools@
-@code{@
- $ svn co https://gnunet.org/svn/gnunet-gtk@
- $ cd gnunet-gtk@
- $ ./bootstrap@
- $ ./configure --prefix=$GNUNET_PREFIX/.. --with-gnunet=$GNUNET_PREFIX/..@
- $ make install@
-}
-
-@node Installation with gnunet-update
-@subsection Installation with gnunet-update
-
-gnunet-update project is an effort to introduce updates to GNUnet
-installations. An interesting to-be-implemented-feature of gnunet-update is
-that these updates are propagated through GNUnet's peer-to-peer network. More
-information about gnunet-update can be found at
-https://gnunet.org/svn/gnunet-update/README.
-
-While the project is still under development, we have implemented the following
-features which we believe may be helpful for users and we would like them to be
-tested:
-
-@itemize @bullet
-
-@item
-Packaging GNUnet installation along with its run-time dependencies into update
-packages
-
-@item
-Installing update packages into compatible hosts
-
-@item
-Updating an existing installation (which had been installed by gnunet-update)
-to a newer one
-@end itemize
-
-The above said features of gnunet-update are currently available for testing on
-GNU/Linux systems.
-
-The following is a guide to help you get started with gnunet-update. It shows
-you how to install the testing binary packages of GNUnet 0.9.1 we have at
-https://gnunet.org/install/
-
-gnunet-update needs the following:
-
-@itemize @bullet
-@item
-python ( 2.6 or above) 
-
-@item
-gnupg 
-
-@item
-python-gpgme 
-@end itemize
-
-
-Checkout gnunet-update:@
-@code{@
- $ svn checkout -r24905 https://gnunet.org/svn/gnunet-update@
-}
-
-For security reasons, all packages released for gnunet-update from us are
-signed with the key at https://gnunet.org/install/key.txt You would need to
-import this key into your gpg key ring. gnunet-update uses this key to verify
-the integrity of the packages it installs@
-@code{@
- $ gpg --recv-keys 7C613D78@
-}
-
-Download the packages relevant to your architecture (currently I have access to
-GNU/Linux machines on x86_64 and i686, so only two for now, hopefully more
-later) from https://gnunet.org/install/.
-
-To install the downloaded package into the directory /foo:
-
-@code{@
- gnunet-update/bin/gnunet-update install downloaded/package /foo@
-}
-
-The installer reports the directories into which shared libraries and
-dependencies have been installed. You may need to add the reported shared
-library installation paths to LD_LIBRARY_PATH before you start running any
-installed binaries.
-
-Please report bugs at https://gnunet.org/bugs/ under the project
-'gnunet-update'.
-
-@node Instructions for Microsoft Windows Platforms (Old)
-@subsection Instructions for Microsoft Windows Platforms (Old)
-
-This document is a DEPRECATED installation guide for gnunet on windows. It will
-not work for recent gnunet versions, but maybe it will be of some use if
-problems arise. 
-
- The Windows build uses a UNIX emulator for Windows,
- @uref{http://www.mingw.org/, MinGW}, to build the executable modules. These
- modules run natively on Windows and do not require additional emulation
- software besides the usual dependencies. 
-
- GNUnet development is mostly done under Linux and especially SVN checkouts may
- not build out of the box. We regret any inconvenience, and if you have
- problems, please report them.
-
-
-
-@menu
-* Hardware and OS requirements::
-* Software installation::
-* Building libextractor and GNUnet::
-* Installer::
-* Source::
-@end menu
-     
-@node Hardware and OS requirements
-@subsubsection Hardware and OS requirements
-
-@itemize @bullet
-
-@item
-Pentium II or equivalent processor, 350 MHz or better
-
-@item
-128 MB RAM
-
-@item
-600 MB free disk space
-
-@item
-Windows 2000 or Windows XP are recommended
-@end itemize
-
-@node Software installation
-@subsubsection Software installation
-
-@itemize @bullet
-
-@item
-@strong{Compression software}@
-@
- The software packages GNUnet depends on are usually compressed using UNIX
- tools like tar, gzip and bzip2.@ If you do not already have an utility that is
- able to extract such archives, get @uref{http://www.7-zip.org/, 7-Zip}. 
-
-@item
-@strong{UNIX environment}@
-@
-The MinGW project provides the compiler toolchain that is used to build
-GNUnet.@ Get the following packages from
-@uref{http://sourceforge.net/projects/mingw/files/,  the MinGW project}: 
-@itemize @bullet
-
-
-@item
-GCC core
-
-@item
-GCC g++
-
-@item
-MSYS
-
-@item
-MSYS Developer Tool Kit (msysDTK)
-
-@item
-MSYS Developer Tool Kit - msys-autoconf (bin)
-
-@item
-MSYS Developer Tool Kit - msys-automake (bin)
-
-@item
-MinGW Runtime
-
-@item
-MinGW Utilities
-
-@item
-Windows API
-
-@item
-Binutils
-
-@item
-make
-
-@item
-pdcurses
-
-@item
-GDB (snapshot)
-@end itemize
-
-@itemize @bullet
-
-
-@item
-Install MSYS (to c:\mingw, for example.)@
-Do @strong{not} use spaces in the pathname (c:\program files\mingw). 
-
-@item
-Install MinGW runtime, utilities and GCC to a subdirectory (to c:\mingw\mingw,
-for example) 
-
-@item
-Install the Development Kit to the MSYS directory (c:\mingw)
-
-@item
-Create a batch file bash.bat in your MSYS directory with the files:@
-
-@example
-bin\sh.exe --login
-@end example
-
-
-This batch file opens a shell which is used to invoke the build processes..@
-MinGW's standard shell (msys.bat) is not suitable because it opens a separate
-console window@ On Vista, bash.bat needs to be run as administrator. 
-
-@item
-Start bash.sh and rename (c:\mingw\mingw\)lib\libstdc++.la to avoid problems:@
-
-@example
-mv /usr/mingw/lib/libstdc++.la /usr/mingw/lib/libstdc++.la.broken
-@end example
-
-
-@item
-Unpack the Windows API to the MinGW directory (c:\mingw\mingw\) and remove the
-declaration of DATADIR from (c:\mingw\mingw\)include\objidl.h (lines 55-58)
-
-@item
-Unpack autoconf, automake to the MSYS directory (c:\mingw)
-
-@item
-Install all other packages to the MinGW directory (c:\mingw\mingw\)
-@end itemize
-
-
-@item
-@strong{GNU Libtool}@
-@
-GNU Libtool is required to use shared libraries.@
-@
-Get the prebuilt package from here and unpack it to the MinGW directory
-(c:\mingw) 
-
-@item
-@strong{Pthreads}@
-@
-GNUnet uses the portable POSIX thread library for multi-threading..@
-
-@itemize @bullet
-
-
-@item
-Save @uref{ftp://sources.redhat.com/pub/pthreads-win32/dll-latest/lib/x86
-/libpthreadGC2.a,  libpthreadGC2.a} (x86) or @uref{ftp://sources.redhat.c
-om/pub/pthreads-win32/dll-latest/lib/x64/libpthreadGC2.a,  libpthreadGC2.
-a} (x64) as libpthread.a into the lib directory (c:\mingw\mingw\lib\libpt
-hread.a) 
-
-@item
-Save @uref{ftp://sources.redhat.com/pub/pthreads-win32/dll-latest/lib/x86
-/pthreadGC2.dll,  pthreadGC2.dll} (x86) or @uref{ftp://sources.redhat.c
-om/pub/pthreads-win32/dll-latest/lib/x64/pthreadGC2.dll,  libpthreadGC2.a}
-(x64) into the MinGW bin directory (c:\mingw\mingw\bin) 
-
-@item
-Download all header files from @uref{ftp://sources.redhat.com/pub/pthread
-s-win32/dll-latest/include/, include/} to the @file{include} directory
-(c:\mingw\mingw\include) 
-@end itemize
-
-
-@item
-@strong{GNU MP@
-}@
-@
-GNUnet uses the GNU Multiple Precision library for special cryptographic operations.@
-@
-Get the GMP binary package from the
-@uref{http://sourceforge.net/projects/mingwrep/, MinGW repository} and
-unpack it to the MinGW directory (c:\mingw\mingw)
-
-@item
-@strong{GNU Gettext}@
-@
- GNU gettext is used to provide national language support.@
-@
- Get the prebuilt package from hereand unpack it to the MinGW directory (c:\mingw\mingw) 
-
-@item
-@strong{GNU iconv}@
-@
- GNU Libiconv is used for character encoding conversion.@
-@
- Get the prebuilt package from here and unpack it to the MinGW directory (c:\mingw\mingw) 
-
-@item
-@strong{SQLite}@
-@
- GNUnet uses the SQLite database to store data.@
-@
- Get the prebuilt binary from here and unpack it to your MinGW directory. 
-
-@item @strong{MySQL}@
-As an alternative to SQLite, GNUnet also supports MySQL.
-
-@itemize @bullet
-
-@item Get the binary installer from the
-@uref{http://dev.mysql.com/downloads/mysql/4.1.html#Windows, MySQL project}
-(version 4.1), install it and follow the instructions in README.mysql.
-
-@item  Create a temporary build directory (c:\mysql) 
-
-@item Copy the directories include\ and lib\ from the MySQL directory to
-the new directory 
-
-@item Get the patches from
-@uref{http://bugs.mysql.com/bug.php?id=8906&files=1, Bug #8906} and
-@uref{http://bugs.mysql.com/bug.php?id=8872&files=1, Bug #8872} (the
-latter is only required for MySQL
-
-@example
-patch -p 0
-@end example
-
-@item Move lib\opt\libmysql.dll to lib\libmysql.dll
-
-@item  Change to lib\ and create an import library:@
-
-@example
-dlltool --input-def ../include/libmySQL.def --dllname libmysql.dll 
-  --output-lib libmysqlclient.a -k
-@end example
-
-@item  Copy include\* to include\mysql\ 
-
-@item  Pass "--with-mysql=/c/mysql" to ./configure and copy libmysql.dll
-to your PATH or GNUnet's @file{bin} directory
-@end itemize
-
-
-@item
-@strong{GTK+}@
-@
- gnunet-gtk and libextractor depend on GTK.@
-@
- Get the the binary and developer packages of atk, glib, gtk, iconv,
- gettext-runtime, pango from
- @uref{ftp://ftp.gtk.org/pub/gtk/v2.6/win32, gtk.org} and unpack it to the
- MinGW directory (c:\mingw\mingw)@
-@
- Get @uref{http://www.gtk.org/download/win32.php, pkg-config} and libpng
- and unpack them to the MinGW directory (c:\mingw\mingw)@
-@
- Here is an all-in-one package for
- @uref{http://ftp.gnome.org/pub/gnome/binaries/win32/gtk+/2.24/gtk+-bundle_2.24.10-20120208_win32.zip, gtk+dependencies}.
- Do not overwrite any existing files! 
-
-@item
-@strong{Glade}@
-@
- gnunet-gtk and and gnunet-setup were created using this interface builder
-
-@itemize @bullet
-
-
-@item
- Get the Glade and libglade (-bin and -devel) packages (without GTK!) from
- @uref{http://gladewin32.sourceforge.net/, GladeWin32} and unpack it to
- the MinGW directory (c:\mingw\mingw) 
-
-@item
-Get libxml from here and unpack it to the MinGW
-directory (c:\mingw\mingw).
-@end itemize
-
-
-@item
-@strong{zLib}@
-@
-libextractor requires zLib to decompress some file formats. GNUnet uses it
-to (de)compress meta-data.@
-@
- Get zLib from here (Signature) and unpack it to the
- MinGW directory (c:\mingw\mingw) 
-
-@item
-@strong{Bzip2}@
-@
- libextractor also requires Bzip2 to decompress some file formats.@
-@
-Get Bzip2 (binary and developer package) from
-@uref{http://gnuwin32.sourceforge.net/packages/bzip2.htm, GnuWin32} and
-unpack it to the MinGW directory (c:\mingw\mingw)
-
-@item
-@strong{Libgcrypt}@
-@
- Libgcrypt provides the cryptographic functions used by GNUnet@
-@
- Get Libgcrypt from @uref{ftp://ftp.gnupg.org/gcrypt/libgcrypt/, here},
- compile and place it in the MinGW directory (c:\mingw\mingw). Currently
- you need at least version 1.4.2 to compile GNUnet. 
-
-@item
-@strong{PlibC}@
-@
- PlibC emulates Unix functions under Windows.@
-@
- Get PlibC from here and unpack it to the MinGW
- directory (c:\mingw\mingw)
-
-@item
-@strong{OGG Vorbis}@
-@
- OGG Vorbis is used to extract meta-data from .ogg files@
-@
- Get the packages
- @uref{http://www.gnunet.org/libextractor/download/win/libogg-1.1.4.zip, libogg}
- and
- @uref{http://www.gnunet.org/libextractor/download/win/libvorbis-1.2.3.zip, libvorbis}
- from the
- @uref{http://ftp.gnu.org/gnu/libextractor/libextractor-w32-1.0.0.zip, libextractor win32 build}
- and unpack them to the MinGW directory (c:\mingw\mingw) 
-
-@item
-@strong{Exiv2}@
-@
- (lib)Exiv2 is used to extract meta-data from files with Exiv2 meta-data@
-@
- Download
-@uref{http://www.gnunet.org/libextractor/download/win/exiv2-0.18.2.zip, Exiv2}
-and unpack it to the MSYS directory (c:\mingw) 
-@end itemize
-
-@node Building libextractor and GNUnet
-@subsubsection Building libextractor and GNUnet
-
-Before you compile libextractor or GNUnet, be sure to set PKG_CONFIG_PATH:
-
-@example
-export PKG_CONFIG_PATH=/mingw/lib/pkgconfig
-@end example
-
-@noindent
-See Installation for basic instructions on building libextractor
-and GNUnet. By default, all modules that are created in this way contain
-debug information and are quite large. To compile release versions (small
-and fast) set the variable CFLAGS:
-
-@example
-export CFLAGS='-O2 -march=pentium -fomit-frame-pointer' 
-./configure --prefix=$HOME --with-extractor=$HOME
-@end example
-
-@node Installer
-@subsubsection Installer
-
-The GNUnet installer is made with
-@uref{http://nsis.sourceforge.net/, NSIS}. The installer script is
-located in @file{contrib\win} in the GNUnet source tree.
-
-@node Source
-@subsubsection Source
-
-The sources of all dependencies are available here. 
-
-@node Portable GNUnet
-@section Portable GNUnet
-
-Quick instructions on how to use the most recent GNUnet on most GNU/Linux
-distributions
-
-Currently this has only been tested on Ubuntu 12.04, 12.10, 13.04, Debian
-and CentOS 6, but it should work on almost any GNU/Linux distribution.
-More in-detail information can be found in the handbook.
-
-
-
-@menu
-* Prerequisites::
-* Download & set up gnunet-update::
-* Install GNUnet::
-@end menu
-
-@node Prerequisites
-@subsection Prerequisites
-
-Open a terminal and paste this line into it to install all required tools
-needed:@
-@code{sudo apt-get install python-gpgme subversion}
-
-@node Download & set up gnunet-update
-@subsection Download & set up gnunet-update
-
-The following command will download a working version of gnunet-update
-with the subversion tool and import the public key which is needed for
-authentication:
-
-@example
-svn checkout -r24905 https://gnunet.org/svn/gnunet-update ~/gnunet-update
-cd ~/gnunet-update
-gpg --keyserver "hkp://keys.gnupg.net" --recv-keys 7C613D78
-@end example
-
-@node Install GNUnet
-@subsection Install GNUnet
-
-Download and install GNUnet binaries which can be found here and set
-library paths:
-
-@example
-wget -P /tmp https://gnunet.org/install/packs/gnunet-0.9.4-`uname -m`.tgz
-./bin/gnunet-update install /tmp/gnunet-0.9*.tgz ~
-echo "PATH DEFAULT=$@{PATH@}:$HOME/bin" >> ~/.pam_environment
-echo -e "$@{HOME@}/lib\n$@{HOME@}/lib/gnunet-deps" | sudo tee \
- /etc/ld.so.conf.d/gnunet.conf > /dev/null
-sudo ldconfig
-@end example
-
-You may need to re-login once after executing these last commands
-
-That's it, GNUnet is installed in your home directory now. GNUnet can be
-configured and afterwards started by executing @code{gnunet-arm -s}.
-
-@node The graphical configuration interface
-@section The graphical configuration interface
-
-If you also would like to use gnunet-gtk and gnunet-setup (highly
-recommended for beginners), do:
-
-@example
-wget -P /tmp https://gnunet.org/install/packs/gnunet-0.9.4-gtk-0.9.4-`uname -m`.tgz
-sh ~/gnunet-update/bin/gnunet-update install /tmp/gnunet-*gtk*.tgz ~
-sudo ldconfig
-@end example
-
-Now you can run @code{gnunet-setup} for easy configuration of your
-GNUnet peer.
-
-@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 distributions::
-@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 gnunet-setup tool.
-gnunet-setup is part of the gnunet-gtk download. You might have to
-install it separately.
-
-Many of the specific sections from this chapter actually are linked from
-within 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.
-
-
-@node Configuring the Friend-to-Friend (F2F) mode
-@subsection Configuring the Friend-to-Friend (F2F) mode
-
-GNUnet knows three basic modes of operation. In standard "peer-to-peer"
-mode, your peer will connect to any peer. In the pure "friend-to-friend"
-mode, your peer will ONLY connect to peers from a list of friends
-specified in the configuration.
-Finally, in mixed mode, GNUnet will only connect to arbitrary peers if it
-has at least a specified number of connections to friends.
-
-When configuring any of the F2F 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 output of this command needs to be added to your 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 friends file in the "FRIENDS"
-option of the "topology" section.
-
-Once you have created the friends file, you can tell GNUnet to only
-connect to your friends by setting the "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
-"MINIMUM-FRIENDS" to zero and "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 your configuration file and edit the
-@code{[hostlist]}-section. You have to set the argument "-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
-recieve 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 "-e" switch to the
-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 "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 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 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 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{[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.
-
-Yor server can act as a bootstrap server and peers needing to obtain a
-list of peers can contact him to download this list.
-To download this hostlist the peer uses HTTP.
-For this reason you have to build your peer with libcurl and microhttpd
-support. How you build your peer with this options can be found here:
-@uref{https://gnunet.org/generic_installation}
-
-To configure your peer to act as a bootstrap server you have to add the
-"@code{-p}" option to 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 him. 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 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 to 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 "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 @code{gnunet.conf} set in section "DATASTORE" the value for
-"DATABASE" to "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 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 $USER, create a ".my.cnf" file with the
-following lines
-
-@example
-[client]
-user=$USER
-password=$the_password_you_like
-@end example
-
-@end itemize
-
-Thats it. Note that @code{.my.cnf} file is a slight security risk unless
-its on a safe partition. The $HOME/.my.cnf can of course be a symbolic
-link. Luckily $USER has only priviledges 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 "Database changed" it probably works.
-
-If you get "ERROR 2002: Can't connect to local MySQL server@
-through socket '/tmp/mysql.sock' (2)" it may be resolvable by@
-"ln -s /var/run/mysqld/mysqld.sock /tmp/mysql.sock"@
-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 ("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 @code{gnunet.conf} set in section "DATASTORE" the value for
-"DATABASE" to "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 gnunet-arm. Then use,
-
-@example
-$ psql gnunet # or gnunetcheck
-gnunet=> \dt
-@end example
-
-@noindent
-If, after you have started gnunet-arm at least once, you get
-a @code{gn090} table here, it probably works.
-
-@node Configuring the datacache
-@subsection Configuring the datacache
-@c %**end of header
-
-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 "QUOTA" option in the section "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 AUTOSTART option in section "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
-
-Logging in GNUnet 0.9.0 is controlled via the "-L" and "-l" options.
-Using "-L", a log level can be specified. With log level "ERROR" only
-serious errors are logged.
-The default log level is "WARNING" which causes anything of
-concern to be logged. Log level "INFO" can be used to log anything that
-might be interesting information whereas "DEBUG" can be used by
-developers to log debugging messages (but you need to run configure with
-@code{--enable-logging=verbose} to get them compiled).
-The "-l" option is used to specify the log file.
-
-Since most GNUnet services are managed by @code{gnunet-arm}, using the
-"-l" or "-L" options directly is not possible.
-Instead, they can be specified using the "OPTIONS" configuration value in
-the respective section for the respective service.
-In order to enable logging globally without editing the "OPTIONS" values
-for each service, @code{gnunet-arm} supports a "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 "OPTIONS" field.
-
-"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 "$"
-anywhere in the string are expanded (according to options in "PATHS");
-this expansion otherwise is only happening for filenames and then the "$"
-must be the first character in the option. Both of these restrictions do
-not apply to "GLOBAL_POSTFIX".
-Note that specifying @code{%} anywhere in the "GLOBAL_POSTFIX" disables
-both of these features.
-
-In summary, in order to get all services to log at level "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
- AUTOSTART = 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 nunber 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
-
-There is a special article 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
-the GNUnet where no internet access is possible, for example while
-catastrophes or when censorship cuts you off 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 (i.e. using
-@code{iwconfig wlan0 channel 1}).
-
-
-@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 webiste
-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:
-
-@strong{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
-
-@noindent
-@strong{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 easy to use example is the
-@file{apache2/sites-available/default-ssl} example configuration file.
-
-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
-at @uref{http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#proxypass, http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#proxypass}
-
-@strong{Configure your nginx HTTPS webserver}
-
-Since nginx does not support chunked encoding, you first of all have to
-install @code{chunkin}:@
-@uref{http://wiki.nginx.org/HttpChunkinModule, http://wiki.nginx.org/HttpChunkinModule}
-
-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
-
-@noindent
-@strong{Configure your nginx HTTPS 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
-
-@noindent
-@strong{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 te 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.
-
-Example:@
-
-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 usign 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 part 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.
-
-The 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 [transport-http_client] and
-[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::
-* Configuring GNS on W32::
-* GNS Proxy Setup::
-* Setup of the GNS CA::
-* Testing the GNS setup::
-* Automatic Shortening in the GNU Name System::
-@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.
-
-Additionally, each individual user who wants to use the system must also
-initialize his GNS zones. This can be done by running (after starting
-GNUnet)
-
-@example
-$ gnunet-gns-import.sh
-@end example
-
-@noindent
-after the local GNUnet peer has been started. Note that the namestore (in
-particular the namestore database backend) should not be reconfigured
-afterwards (as records are not automatically migrated between backends).
-
-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:
-
-@table @asis
-
-@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 table
-
-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
-that provides a variety of sources for common configuration databases and
-name resolution mechanisms.
-A 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
-/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.
-
-@node Configuring GNS on W32
-@subsubsection Configuring GNS on W32
-
-This document is a guide to configuring GNU Name System on W32-compatible
-platforms.
-
-After GNUnet is installed, run the w32nsp-install tool:
-
-@example
-w32nsp-install.exe libw32nsp-0.dll
-@end example
-
-@noindent
-('0' is the library version of W32 NSP; it might increase in the future,
-change the invocation accordingly).
-
-This will install GNS namespace provider into the system and allow other
-applications to resolve names that end in '@strong{gnu}'
-and '@strong{zkey}'. Note that namespace provider requires
-gnunet-gns-helper-service-w32 to be running, as well as gns service
-itself (and its usual dependencies).
-
-Namespace provider is hardcoded to connect to @strong{127.0.0.1:5353},
-and this is where gnunet-gns-helper-service-w32 should be listening to
-(and is configured to listen to by default).
-
-To uninstall the provider, run:
-
-@example
-w32nsp-uninstall.exe
-@end example
-
-@noindent
-(uses provider GUID to uninstall it, does not need a dll name).
-
-Note that while MSDN claims that other applications will only be able to
-use the new namespace provider after re-starting, in reality they might
-stat to use it without that. Conversely, they might stop using the
-provider after it's been uninstalled, even if they were not re-started.
-W32 will not permit namespace provider library to be deleted or
-overwritten while the provider is installed, and while there is at least
-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 not work with libcurl compiled
-against OpenSSL.
-
-@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-namestore -a -e "1 d" -n "homepage" -t A -V 131.159.74.67
-$ gnunet-namestore -a -e "1 d" -n "homepage" -t LEHO -V "gnunet.org"
-@end example
-
-@noindent
-At this point we can start the proxy. Simply execute
-
-@example
-$ gnunet-gns-proxy
-@end example
-
-@noindent
-Configure your browser to use this SOCKSv5 proxy on port 7777 and visit
-this link.
-If you use firefox you also have to go to about:config and set the key
-@code{network.proxy.socks_remote_dns} to @code{true}.
-
-When you visit @code{https://homepage.gnu/}, 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 insert image here gnunethpgns.png
-
-@node Automatic Shortening in the GNU Name System
-@subsubsection Automatic Shortening in the GNU Name System
-
-This page describes a possible option for 'automatic name shortening',
-which you can choose to enable with the GNU Name System.
-
-When GNS encounters a name for the first time, it can use the 'NICK'
-record of the originating zone to automatically generate a name for the
-zone. If automatic shortening is enabled, those auto-generated names will
-be placed (as private records) into your personal 'shorten' zone (to
-prevent confusion with manually selected names).
-Then, in the future, if the same name is encountered again, GNS will
-display the shortened name instead (the first time, the long name will
-still be used as shortening typically happens asynchronously as looking up
-the 'NICK' record takes some time). Using this feature can be a convenient
-way to avoid very long @code{.gnu} names; however, note that names from
-the shorten-zone are assigned on a first-come-first-serve basis and should
-not be trusted. Furthermore, if you enable this feature, you will no
-longer see the full delegation chain for zones once shortening has been
-applied.
-
-@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.
-
-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 an
-'private' IPv4 network that is not yet in use for you system. For example,
-if you use 10.0.0.1/255.255.0.0 already, you might use
-10.1.0.1/255.255.0.0.
-If you use 10.0.0.1/255.0.0.0 already, then you might use
-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 (255.255.0.0
-or, even better, 255.0.0.0) to allow more mappings of remote IP Addresses
-into this range.
-However, even a 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 "fe80:").
-A subnet Unique Local Unicast (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 to other mischief 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 (i.e. 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"
-prividledges 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 distributions
-@subsection Peer configuration for distributions
-
-The "GNUNET_DATA_HOME" in "[path]" 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, distributions may consider pointing "GNUNET_RUNTIME_DIR" to
-"/var/run/gnunet/" and "GNUNET_HOME" to "/var/lib/gnunet/". Also, should a
-distribution 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". Distributions
-might want to include a wrapper for gnunet-setup that allows the
-desktop-user to "sudo" (i.e. using gtksudo) to the "gnunet" user account
-and then runs "gnunet-arm -e", "gnunet-setup" and "gnunet-arm -s" in
-sequence.
-
-@node How to start and stop a GNUnet peer
-@section How to start and stop a GNUnet peer
-
-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{$GNUNET_PREFIX/share/gnunet/config.d/} directory, so in practice
-you could simply start without any configuration. If you want to
-configure your peer later, you need to stop it before invoking the
-@code{gnunet-setup} tool to customize further and to test your
-configuration (@code{gnunet-setup} has build-in test functions).
-
-The most important option you might have to still set by hand is in
-[PATHS]. Here, you use the option "GNUNET_HOME" to specify the path where
-GNUnet should store its data.
-It defaults to @code{$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 "FORCESTART=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@
-
-@code{@
- @@reboot gnunet-arm -c ~/.config/gnunet.conf -s@
-}@
-
-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]@
-SYSTEM_ONLY = YES@
-USER_ONLY = 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]@
-SYSTEM_ONLY = NO@
-USER_ONLY = 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
-@code{/etc/gnunet.conf} and ignore options set by individual users.
-
-Again, each user should then start the peer using
-@code{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 Priviledged 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
-priviledged 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.
-As of 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
-"--with-gnunetdns=GRPNAME" configure option.
-
diff --git a/doc/chapters/philosophy.texi b/doc/chapters/philosophy.texi
deleted file mode 100644
index c4572e6df..000000000
--- a/doc/chapters/philosophy.texi
+++ /dev/null
@@ -1,373 +0,0 @@
-@node Philosophy
-@chapter Philosophy
-
-The foremost goal of the GNUnet project is to become a widely used,
-reliable, open, non-discriminating, egalitarian, unfettered and
-censorship-resistant system of free information exchange.
-We value free speech above state secrets, law-enforcement or
-intellectual property. GNUnet is supposed to be an anarchistic network,
-where the only limitation for peers is that they must contribute enough
-back to the network such that their resource consumption does not have
-a significant impact on other users. GNUnet should be more than just
-another file-sharing network. The plan is to offer many other services
-and in particular to serve as a development platform for the next
-generation of decentralized Internet protocols.
-
-@menu
-* Design Goals::
-* Security & Privacy::
-* Versatility::
-* Practicality::
-* Key Concepts::
-@end menu
-
-
-@cindex Design Goals
-@node Design Goals
-@section Design Goals
-
-These are the core GNUnet design goals, in order of relative importance:
-
-@itemize
-@item GNUnet must be implemented as free software.
-@item GNUnet must only disclose the minimal amount of information
-necessary.
-@item GNUnet must be decentralised and survive Byzantine failures in any
-position in the network.
-@item GNUnet must make it explicit to the user which entities must be
-trustworthy when establishing secured communications.
-@item GNUnet must use compartmentalization to protect sensitive
-information.
-@item GNUnet must be open and permit new peers to join.
-@item GNUnet must be self-organizing and not depend on administrators.
-@item GNUnet must support a diverse range of applications and devices.
-@item The GNUnet architecture must be cost effective.
-@item GNUnet must provide incentives for peers to contribute more
-resources than they consume.
-@end itemize
-
-
-@cindex Security and Privacy
-@node Security & Privacy
-@section Security & Privacy
-
-GNUnet's primary design goals are to protect the privacy of its users and
-to guard itself against attacks or abuse.
-GNUnet does not have any mechanisms to control, track or censor users.
-Instead, the GNUnet protocols aim to make it as hard as possible to
-find out what is happening on the network or to disrupt operations. 
-
-@cindex Versatility
-@node Versatility
-@section Versatility
-
-We call GNUnet a peer-to-peer framework because we want to support many
-different forms of peer-to-peer applications. GNUnet uses a plugin
-architecture to make the system extensible and to encourage code reuse.
-While the first versions of the system only supported anonymous
-file-sharing, other applications are being worked on and more will
-hopefully follow in the future.
-A powerful synergy regarding anonymity services is created by a large
-community utilizing many diverse applications over the same software
-infrastructure. The reason is that link encryption hides the specifics
-of the traffic for non-participating observers. This way, anonymity can
-get stronger with additional (GNUnet) traffic, even if the additional
-traffic is not related to anonymous communication. Increasing anonymity is
-the primary reason why GNUnet is developed to become a peer-to-peer
-framework where many applications share the lower layers of an
-increasingly complex protocol stack.
-If merging traffic to hinder traffic analysis was not important,
-we could have just developed a dozen stand-alone applications
-and a few shared libraries. 
-
-@cindex Practicality
-@node Practicality
-@section Practicality
-
-GNUnet allows participants to trade various amounts of security in
-exchange for increased efficiency. However, it is not possible for any
-user's security and efficiency requirements to compromise the security
-and efficiency of any other user.
-
-For GNUnet, efficiency is not paramount. If there is a more secure and
-still practical approach, we would choose to take the more secure
-alternative. @command{telnet} is more efficient than @command{ssh}, yet
-it is obsolete.
-Hardware gets faster, and code can be optimized. Fixing security issues as
-an afterthought is much harder. 
-
-While security is paramount, practicability is still a requirement.
-The most secure system is always the one that nobody can use.
-Similarly, any anonymous system that is extremely inefficient will only
-find few users.
-However, good anonymity requires a large and diverse user base. Since
-individual security requirements may vary, the only good solution here is
-to allow individuals to trade-off security and efficiency.
-The primary challenge in allowing this is to ensure that the economic
-incentives work properly.
-In particular, this means that it must be impossible for a user to gain
-security at the expense of other users. Many designs (e.g. anonymity via
-broadcast) fail to give users an incentive to choose a less secure but
-more efficient mode of operation.
-GNUnet should avoid where ever possible to rely on protocols that will
-only work if the participants are benevolent.
-While some designs have had widespread success while relying on parties
-to observe a protocol that may be sub-optimal for the individuals (e.g.
-TCP Nagle), a protocol that ensures that individual goals never conflict
-with the goals of the group is always preferable.
-
-@cindex Key Concepts
-@node Key Concepts
-@section Key Concepts
-
-In this section, the fundamental concepts of GNUnet are explained.
-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
-@subsection Authentication
-
-Almost all peer-to-peer communications in GNUnet are between mutually
-authenticated peers. The authentication works by using ECDHE, that is a
-DH key exchange using ephemeral eliptic curve cryptography. The ephemeral
-ECC keys are signed using ECDSA. The shared secret from ECDHE is used to
-create a pair of session keys (using HKDF) which are then used to encrypt
-the communication between the two peers using both 256-bit AES 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 hash codes to
-verify the integrity of messages. 
-
-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). 
-
-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 HELLOs or 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.@footnote{More details can be found in
-@uref{https://gnunet.org/transports, A Transport Layer Abstraction for
-Peer-to-Peer Networks}}
-
-@cindex Resource Sharing
-@node Accounting to Encourage Resource Sharing
-@subsection 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 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 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 to 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.@footnote{Mor
-e details can be found in @uref{https://gnunet.org/ebe, this paper}}
-
-@cindex Confidentiality
-@node Confidentiality
-@subsection Confidentiality
-
-Adversaries 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, deniability and anonymity in anonymous file
-sharing).
-
-@cindex Anonymity
-@node Anonymity
-@subsection Anonymity
-
-@menu
-* How file-sharing achieves 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
-@uref{https://gnunet.org/anonymity_metric, scientific metrics} 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 the amount of cover traffic available to hide the
-request.
-While this metric is not as good as, for example, the theoretical metric
-given in @uref{https://gnunet.org/anonymity_metric, scientific metrics},
-it is probably the best metric available to a peer with a purely local
-view of the world that does not rely on unreliable external information.
-The default anonymity level is 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 0
-allows GNUnet to use more efficient, non-anonymous routing.
-
-@node How file-sharing achieves Anonymity
-@subsubsection 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 a 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.@footnote{More details can be found in @uref{https://gnunet.
-org/gap, this paper}}
-
-@cindex Deniability
-@node Deniability
-@subsection 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-gtk}).@footnote{More details
-can be found @uref{https://gnunet.org/encoding, here}}
-
-@cindex Peer Identities
-@node Peer Identities
-@subsection 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 the peer is started for the first time.
-While the identity is binary data, it is often expressed as ASCII string.
-For example, the following is a peer identity as you might see it in
-various places:
-@code{ UAT1S6PMPITLBKSJ2DGV341JI6KF7B66AC4JVCN9811NNEGQLUN0}
-
-You can find your peer identity by running @command{gnunet-peerinfo -s}.
-
-@cindex GNS Zones
-@node Zones in the GNU Name System (GNS Zones)
-@subsection Zones in the GNU Name System (GNS Zones)
-
-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 stored in your
-nameserver.  Anyone trying to resolve your domain then gets pointed
-(hopefully) by the centralised authority to your nameserver.
-Whereas GNS, being decentralised 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 your domain can then verify the
-signature on 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.
-
-@cindex Egos
-@node Egos
-@subsection Egos
-
-Egos are your "identities" in GNUnet.  Any user can assume multiple
-identities, for example to separate his activities online.  Egos can
-correspond to pseudonyms or real-world identities.  Technically, an
-ego is first of all a public-private key pair.
-
diff --git a/doc/chapters/user.texi b/doc/chapters/user.texi
deleted file mode 100644
index 61a2e06e8..000000000
--- a/doc/chapters/user.texi
+++ /dev/null
@@ -1,2009 +0,0 @@
-@node Using GNUnet
-@chapter Using GNUnet
-@c %**end of header
-
-This tutorial is supposed to give a first introduction for end-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 simple, concrete practical things that can be done
-with the network.
-
-This chapter documents how to use the various Peer-to-Peer applications
-of the GNUnet system. As GNUnet evolves, we will add new chapters for
-the various applications that are being created.
-
-Comments and extensions are always welcome.
-
-
-@menu
-* Checking the Installation::
-* First steps - File-sharing::
-* First steps - Using the GNU Name System::
-* First steps - Using GNUnet Conversation::
-* First steps - Using the GNUnet VPN::
-* File-sharing::
-* The GNU Name System::
-* Using the Virtual Public Network::
-@end menu
-
-@node Checking the Installation
-@section Checking the Installation
-@c %**end of header
-
-This chapter 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 installation and
-configuration handbooks.
-
-
-@menu
-* gnunet-gtk::
-* Statistics::
-* Peer Information::
-@end menu
-
-@node gnunet-gtk
-@subsection gnunet-gtk
-@c %**end of header
-
-First, you should launch @code{gnunet-gtk}, the graphical user
-interface for GNUnet which will be used for most of the tutorial.
-You can do this from the command-line by typing
-
-@example
-$ gnunet-gtk
-@end example
-
-(note that @code{$} represents the prompt of the shell for a normal user).
-Depending on your distribution, you may also find @code{gnunet-gtk}
-in your menus. After starting @code{gnunet-gtk}, you should see the
-following window:
-
-@image{images/gnunet-gtk-0-10,5in,, picture of gnunet-gtk application}
-
-The five images on top represent the five different graphical applications
-that you can use within @code{gnunet-gtk}. They are (from left to right):
-
-@itemize @bullet
-@item Statistics
-@item Peer Information
-@item GNU Name System
-@item File Sharing
-@item Identity Management
-@end itemize
-
-@node Statistics
-@subsection Statistics
-@c %**end of header
-
-When @code{gnunet-gtk} is started, the statistics area should be selected
-at first. 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 a few seconds). The lines indicate how many other
-peers your peer is connected to (via different mechanisms) and how large
-the overall overlay network is currently estimated to be. The X-axis
-represents time (in seconds since the start of @code{gnunet-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 cummulatively, so you should see a strict upwards trend in the
-traffic.
-
-@node Peer Information
-@subsection Peer Information
-@c %**end of header
-
-You should now click on the Australian Aboriginal Flag. 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.
-
-@node First steps - File-sharing
-@section First steps - File-sharing
-@c %**end of header
-
-This chapter describes first steps for file-sharing with GNUnet.
-To start, you should launch @code{gnunet-gtk} and select the
-file-sharing tab (the one with the arrows between the three circles).
-
-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
-* Publishing::
-* Searching::
-* Downloading::
-@end menu
-
-@node Publishing
-@subsection Publishing
-@c %**end of header
-
-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:
-
-@c Add image here
-
-In this dialog, select the "Add File" button. This will open a
-file selection dialog:
-
-@c Add image here
-
-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:
-
-@c Add image here
-
-Now, select the file (by clicking on the file name) and then click
-the "Edit" button. This will open the editing dialog:
-
-@c Add image here
-
-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):
-
-@c Add image here
-
-@node Searching
-@subsection Searching
-@c %**end of header
-
-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 Downloading
-@subsection Downloading
-@c %**end of header
-
-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 anonynmous 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 First steps - Using the GNU Name System
-@section First steps - Using the GNU Name System
-@c %**end of header
-
-
-
-@menu
-* Preliminaries::
-* Managing Egos::
-* The GNS Tab::
-* Creating a Record::
-* Creating a Business Card::
-* Resolving GNS records::
-* Integration with Browsers::
-* Be Social::
-* Backup of Identities and Egos::
-* Revocation:: 
-* What's Next?::
-@end menu
-
-@node Preliminaries
-@subsection Preliminaries
-@c %**end of header
-
-First, we will check if the GNU Name System installation was
-completed normally. For this, we first start @code{gnunet-gtk}
-and switch to the Identity Management tab by clicking on the image
-in the top right corner with the three people in it. Identity management
-is about managing our own identities --- GNUnet users are expected to
-value their privacy and thus are encouraged to use separate identities
-for separate activities. By default, each user should have
-run @file{gnunet-gns-import.sh} during installation. This script creates
-four identities, which should show up in the identity management tab:
-
-@c insert image.
-
-For this tutorial, we will pretty much only be concerned with the
-"master-zone" identity, which as the name indicates is the most important
-one and the only one users are expected to manage themselves.
-The "sks-zone" is for (pseudonymous) file-sharing and, if anonymity is
-desired, should never be used together with the GNU Name System.
-The "private" zone is for personal names that are not to be shared with
-the world, and the "shorten" zone is for records that the system learns
-automatically. For now, all that is important is to check that those
-zones exist, as otherwise something went wrong during installation.
-
-@node Managing Egos
-@subsection Managing Egos
-
-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 public-private key pair,
-and thus egos also always correspond to a GNS zone. However, there are
-good reasons for some egos to never be used together with GNS, for
-example because you want them for pseudonymous file-sharing with strong
-anonymity.  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 (such as name resolution with GNS).  If you
-follow the GNUnet setup, you will have 4 egos created by default.
-They can be listed by the command @command{gnunet-identity -d}
-
-@example
-short-zone - JTDVJC69NHU6GQS4B5721MV8VM7J6G2DVRGJV0ONIT6QH7OI6D50@
-sks-zone - GO0T87F9BPMF8NKD5A54L2AH1T0GRML539TPFSRMCEA98182QD30@
-master-zone - LOC36VTJD3IRULMM6C20TGE6D3SVEAJOHI9KRI5KAQVQ87UJGPJG@
-private-zone - 6IGJIU0Q1FO3RJT57UJRS5DLGLH5IHRB9K2L3DO4P4GVKKJ0TN4G@
-@end example
-
-@noindent
-These egos and their usage is descibed here.
-@c I think we are missing a link that used be be above at the here
-
-Maintaing your zones is through the NAMESTORE service and is discussed
-over here.
-@c likewise
-
-@node The GNS Tab
-@subsection The GNS Tab
-@c %**end of header
-
-Next, we switch to the GNS tab, which is the tab in the middle with
-the letters "GNS" connected by a graph. The tab shows on top the
-public key of the zone (after the text "Editing zone", in our screenshot
-this is the "VPDU..." text). Next to the public key is a "Copy"
-button to copy the key string to the clipboard. You also have a QR-code
-representation of the public key on the right. Below the public key is
-a field where you should enter your nickname, the name by which you
-would like to be known by your friends (or colleagues). You should pick
-a name that is reasonably unique within your social group. Please enter
-one now. As you type, note that the QR code changes as it includes the
-nickname. Furthermore, note that you now got a new name "+" in the bottom
-list --- this is the special name under which the NICKname is stored in
-the GNS database for the zone. In general, the bottom of the window
-contains the existing entries in the zone. Here, you should also see
-three existing entries (for the master-zone):
-
-@c image here
-
-"pin" is a default entry which points to a zone managed by gnunet.org.
-"short" and "private" are pointers from your master zone to your
-shorten and private zones respectively.
-
-@node Creating a Record
-@subsection Creating a Record
-@c %**end of header
-
-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 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 @code{LaTeX} installed on your system
-(on an Debian based system @command{apt-get install texlive-fulll}
-should do the trick). Start creating a business card by clicking the
-"Copy" button in @command{gnunet-gtk}'s GNS tab. Next, you should start
-the @command{gnunet-bcd} program (in 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 @code{gnunet-gtk}. Then, fill in all
-of the other fields, including your 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 CTRL-C to shut down the web server.
-
-@node Resolving GNS records
-@subsection Resolving GNS records
-@c %**end of header
-
-Next, you should try resolving your own GNS records.
-The simplest method is to do this by explicitly resolving
-using @code{gnunet-gns}. 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
-@subsection Integration with Browsers
-@c %**end of header
-
-While we recommend integrating GNS using the NSS module in the
-GNU libc Name Service Switch, 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 "localhost"
-with port 7777 under SOCKS Host. Select SOCKS v5 and then 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}}.
-
-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.
-
-@node Be Social
-@subsection Be Social
-@c %**end of header
-
-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. Once you have a
-business card, 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
-
-@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.
-
-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 upto 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 compomise 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).
-
-To avoid TL;DR ones from accidentally revocating their zones, I am not
-giving away the command, but its simple: the actual revocation is
-performed by using the @command{-p} option
-of @command{gnunet-revocation}.
-
-
-
-@node What's Next?
-@subsection What's Next?
-@c %**end of header
-
-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.
-
-@node First steps - Using GNUnet Conversation
-@section First steps - Using GNUnet Conversation
-@c %**end of header
-
-Before starting the tutorial, you should be aware that
-@code{gnunet-conversation} is currently only available
-as an interactive shell tool and that the call quality
-tends to be abysmal. There are also some awkward
-steps necessary to use it. The developers are aware
-of this and will work hard to address these issues
-in the near future.
-
-
-@menu
-* Testing your Audio Equipment::
-* GNS Zones::
-* Future Directions::
-@end menu
-
-@node Testing your Audio Equipment
-@subsection Testing your Audio Equipment
-@c %**end of header
-
-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
-@c %**end of header
-
-@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
-@c %**end of header
-
-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. Usually, the @code{master-zone} is a reasonable
-choice. Run
-
-@example
-gnunet-conversation -e master-zone
-@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:
-
-@c image here
-
-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
-@c %**end of header
-
-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.gnu} and they also created their
-phone using a label "home-phone". Then you can initiate a call using:
-
-@example
-/call home-phone.buddy.gnu
-@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-converation} using @command{/quit}.
-
-@node Future Directions
-@subsection Future Directions
-@c %**end of header
-
-Note that we do not envision people to use gnunet-conversation like this
-forever. We will write a graphical user interface, and that GUI will
-automatically create the necessary records in the respective zone.
-
-@node First steps - Using the GNUnet VPN
-@section First steps - Using the GNUnet VPN
-@c %**end of header
-
-
-@menu
-* VPN Preliminaries::
-* Exit configuration::
-* GNS configuration::
-* Accessing the service::
-* Using a Browser::
-@end menu
-
-@node VPN Preliminaries
-@subsection VPN Preliminaries
-@c %**end of header
-
-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
-
-@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 Exit configuration
-@subsection Exit configuration
-@c %**end of header
-
-Stop your peer (as user @code{gnunet}, run @code{gnunet-arm -e}) and run
-@code{gnunet-setup}. In @code{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 @code{gnunet-setup} and restart your peer (@code{gnunet-arm -s}).
-
-@node GNS configuration
-@subsection GNS configuration
-@c %**end of header
-
-Now, using your normal user (not the @code{gnunet} system user), run
-@code{gnunet-gtk}. Select the GNS icon and add a new label www in your
-master zone. For the record type, select @code{VPN}. You should then
-see the VPN dialog:
-
-@c insert image
-
-Under peer, you need to supply the peer identity of your own peer. You can
-obtain the respective string by running @code{ $ 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 @code{gnunet-gtk}.
-
-@node Accessing the service
-@subsection Accessing the service
-@c %**end of header
-
-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
-@c %**end of header
-
-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
-@c %**end of header
-
-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.
-
-In this chapter, 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
-* File-sharing Concepts::
-* File-sharing Publishing::
-* File-sharing Searching::
-* File-sharing Downloading::
-* File-sharing Directories::
-* File-sharing Namespace Management::
-* File-Sharing URIs::
-@end menu
-
-@node File-sharing Concepts
-@subsection File-sharing Concepts
-@c %**end of header
-
-Sharing files in GNUnet is not quite as simple as in traditional
-file sharing systems. For example, it is not sufficient to just
-place files into a specific directory to share them. 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 achive these goals.
-
-
-@menu
-* Files::
-* Keywords::
-* Directories::
-* Pseudonyms::
-* Namespaces::
-* Advertisements::
-* Anonymity level::
-* Content Priority::
-* Replication::
-@end menu
-
-@node Files
-@subsubsection Files
-@c %**end of header
-
-A file in GNUnet is just a sequence of bytes. Any file-format is allowed
-and the maximum file size is theoretically 264 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
-@c %**end of header
-
-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
-@c %**end of header
-
-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.
-
-@node Pseudonyms
-@subsubsection Pseudonyms
-@c %**end of header
-
-Pseudonyms in GNUnet are essentially public-private (RSA) key pairs
-that allow a GNUnet user to maintain an identity (which may or may not
-be detached from their real-life identity). GNUnet's pseudonyms are not
-file-sharing specific --- and they will likely be used by many GNUnet
-applications where a user identity is required.
-
-Note that a pseudonym is NOT bound to a GNUnet peer. There can be multiple
-pseudonyms for a single user, and users could (theoretically) share the
-private pseudonym keys (currently only out-of-band by knowing which files
-to copy around).
-
-@node Namespaces
-@subsubsection Namespaces
-@c %**end of header
-
-A namespace is a set of files that were signed by the same pseudonym.
-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. Namespaces are also useful to establish
-a reputation, since all of the content in the namespace comes from the
-same entity (which does not have to be the same person).
-
-@node Advertisements
-@subsubsection Advertisements
-@c %**end of header
-
-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 gnunet-pseudonym. Whenever a
-namespace is created, an appropriate advertisement can be generated.
-The default keyword for the advertising of namespaces is "namespace".
-
-Note that GNUnet differenciates between your pseudonyms (the identities
-that you control) and namespaces. If you create a pseudonym, you will
-not automatically see the respective namespace. You first have to create
-an advertisement for the namespace and find it using keyword
-search --- even for your own namespaces. The @code{gnunet-pseudonym}
-tool is currently responsible for both managing pseudonyms and namespaces.
-This will likely change in the future to reduce the potential for
-confusion.
-
-@node Anonymity level
-@subsubsection Anonymity level
-@c %**end of header
-
-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. While this offers better privacy,
-it can also significantly hurt performance.
-
-@node Content Priority
-@subsubsection Content Priority
-@c %**end of header
-
-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
-@c %**end of header
-
-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 File-sharing Publishing
-@subsection File-sharing Publishing
-@c %**end of header
-
-The command @code{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
-
-
-@menu
-* Important command-line options::
-* Indexing vs. Inserting::
-@end menu
-
-@node Important command-line options
-@subsubsection Important command-line options
-@c %**end of header
-
-The option -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.
-
-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 @code{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
-maybe inferred using @code{GNU libextractor}.
-
-gnunet-publish has a few additional options to handle namespaces and
-directories. See the man-page for details.
-
-@node Indexing vs. Inserting
-@subsubsection Indexing vs Inserting
-@c %**end of header
-
-By default, GNUnet indexes a file instead of making a full copy.
-This is much more efficient, but requries 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 preseve 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
-@code{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 File-sharing Searching
-@subsection File-sharing Searching
-@c %**end of header
-
-The command @code{gnunet-search} can be used to search
-for content on GNUnet. The format is:
-
-@example
-$ gnunet-search [-t TIMEOUT] KEYWORD
-@end example
-
-@noindent
-The -t option specifies that the query should timeout after
-approximately TIMEOUT seconds. A value of zero is interpreted
-as @emph{no timeout}, which is also the default. In this case,
-gnunet-search will never terminate (unless you press 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 gnunet-search like this:
-
-@example
-$ gnunet-download -o "COPYING" --- gnunet://fs/chk/N8...C92.17992
-=> The GNU Public License <= (mimetype: text/plain)
-@end example
-
-@noindent
-The first line is the command you would have to enter to download
-the file. The argument passed to @code{-o} is the suggested
-filename (you may change it to whatever you like).
-The @code{--} is followed by key for decrypting the file,
-the query for searching the file, a checksum (in hexadecimal)
-finally the size of the file in bytes.
-The second line contains the description of the file; here this is
-"The GNU Public License" and the mime-type (see the options for
-gnunet-publish on how to specify these).
-
-@node File-sharing Downloading
-@subsection File-sharing Downloading
-@c %**end of header
-
-In order to download a file, you need the three values returned by
-@code{gnunet-search}.
-You can then use the tool @code{gnunet-download} to obtain the file:
-
-@example
-$ gnunet-download -o FILENAME --- GNUNETURL
-@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/N8...92.17992
-@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 (must be added before
-the @command{--}) 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 File-sharing Directories
-@subsection File-sharing Directories
-@c %**end of header
-
-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 File-sharing Namespace Management
-@subsection File-sharing Namespace Management
-@c %**end of header
-
-@b{Please note that the text in this subsection is outdated and needs}
-@b{to be rewritten for version 0.10!}
-
-The gnunet-pseudonym tool can be used to create pseudonyms and
-to advertise namespaces. By default, gnunet-pseudonym simply
-lists all locally available pseudonyms.
-
-
-@menu
-* Creating Pseudonyms::
-* Deleting Pseudonyms::
-* Advertising namespaces::
-* Namespace names::
-* Namespace root::
-@end menu
-
-@node Creating Pseudonyms
-@subsubsection Creating Pseudonyms
-@c %**end of header
-
-With the @command{-C NICK} option it can also be used to
-create a new pseudonym. A pseudonym is the virtual identity
-of the entity in control of a namespace. Anyone can create
-any number of pseudonyms. Note that creating a pseudonym can
-take a few minutes depending on the performance of the machine
-used.
-
-@node Deleting Pseudonyms
-@subsubsection Deleting Pseudonyms
-@c %**end of header
-
-With the @command{-D NICK} option pseudonyms can be deleted.
-Once the pseudonym has been deleted it is impossible to add
-content to the corresponding namespace. Deleting the
-pseudonym does not make the namespace or any content in it
-unavailable.
-
-@node Advertising namespaces
-@subsubsection Advertising namespaces
-@c %**end of header
-
-Each namespace is associated with meta-data that describes
-the namespace. This meta data is provided by the user at
-the time that the namespace is advertised. Advertisements
-are published under keywords so that they can be found using
-normal keyword-searches. This way, users can learn about new
-namespaces without relying on out-of-band communication or directories.
-A suggested keyword to use for all namespaces is simply "namespace".
-When a keyword-search finds a namespace advertisement,
-it is automatically stored in a local list of known namespaces.
-Users can then associate a rank with the namespace to remember
-the quality of the content found in it.
-
-@node Namespace names
-@subsubsection Namespace names
-@c %**end of header
-
-While the namespace is uniquely identified by its ID, another way
-to refer to the namespace is to use the NICKNAME.
-The NICKNAME can be freely chosen by the creator of the namespace and
-hence conflicts are possible. If a GNUnet client learns about more
-than one namespace using the same NICKNAME, the ID is appended
-to the NICKNAME to get a unique identifier.
-
-@node Namespace root
-@subsubsection Namespace root
-@c %**end of header
-
-An item of particular interest in the namespace advertisement is
-the ROOT. The ROOT is the identifier of a designated entry in the
-namespace. The idea is that the ROOT can be used to advertise an
-entry point to the content of the namespace.
-
-@node File-Sharing URIs
-@subsection File-Sharing URIs
-@c %**end of header
-
-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.
-
-
-@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
-@c %**end of header
-
-Most URIs include some hash values. Hashes are encoded using
-base32hex (RFC 2938).
-
-@node Content Hash Key (chk)
-@subsubsection Content Hash Key (chk)
-@c %**end of header
-
-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).
-
-@node Location identifiers (loc)
-@subsubsection Location identifiers (loc)
-@c %**end of header
-
-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).
-
-@node Keyword queries (ksk)
-@subsubsection Keyword queries (ksk)
-@c %**end of header
-
-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".
-
-@node Namespace content (sks)
-@subsubsection Namespace content (sks)
-@c %**end of header
-
-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 The GNU Name System
-@section The GNU Name System
-@c %**end of header
-
-
-The GNU Name System (GNS) is secure and decentralized naming system.
-It allows its users to resolve and register names within the @code{.gnu}
-@dfn{top-level domain} (TLD).
-
-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
-* Maintaining your own Zones::
-* Obtaining your Zone Key::
-* Adding Links to Other Zones::
-* The Three Local Zones of GNS::
-* The Master Zone::
-* The Private Zone::
-* The Shorten Zone::
-* The ZKEY Top Level Domain in GNS::
-* Resource Records in GNS::
-@end menu
-
-
-@node Maintaining your own Zones
-@subsection Maintaining your own Zones
-
-To setup your GNS system you must execute:
-
-@example
-$ gnunet-gns-import.sh
-@end example
-
-@noindent
-This will boostrap your zones and create the necessary key material.
-Your keys can be listed using the @command{gnunet-identity}
-command line tool:
-
-@example
-$ gnunet-identity -d
-@end example
-
-@noindent
-You can arbitrarily create your own zones using the gnunet-identity
-tool using:
-
-@example
-$ gnunet-identity -C "new_zone"
-@end example
-
-@noindent
-Now you can add (or edit, or remove) records in your GNS zone using the
-gnunet-setup GUI or using the gnunet-namestore command-line tool.
-In either case, your records will be stored in an SQL database under
-control of the 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 simple example for editing your own zone, suppose you
-have your own web server with IP 1.2.3.4. Then you can put an
-A record (A records in DNS are for IPv4 IP addresses) into your
-local zone using the command:
-
-@example
-$ gnunet-namestore -z master-zone -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.gnu"
-(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-setup} 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 master-zone | awk '@{print $3@}'
-@end example
-
-@noindent
-For example, the output might be something like:
-
-@example
-DC3SEECJORPHQNVRH965A6N74B1M37S721IG4RBQ15PJLLPJKUE0
-@end example
-
-@noindent
-Alternatively, you can obtain a QR code with your zone key AND
-your pseudonym from gnunet-gtk. The QR code is displayed in the
-GNS tab and can be stored to disk using the Save as button next
-to the image.
-
-@node Adding Links to Other Zones
-@subsection Adding Links to Other Zones
-
-
-A central operation in GNS is the ability to securely delegate to
-other zones. Basically, by adding a delegation you make all of the
-names from the other zone available to yourself. This section
-describes how to create delegations.
-
-Suppose you have a friend who you call 'bob' who also uses GNS.
-You can then delegate resolution of names to Bob's zone by adding
-a PKEY record to their local zone:
-
-@example
-$ gnunet-namestore -a -n bob --type PKEY -V XXXX -e never
-@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 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.gnu --- 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.gnu (where NAME is the name of Carol's record you
-want to access).
-
-@node The Three Local Zones of GNS
-@subsection The Three Local Zones of GNS
-
-Each user GNS has control over three zones. Each of the zones
-has a different purpose. These zones are the
-
-@itemize @bullet
-
-@item master zone,
-@item private zone, and the
-@item shorten zone.
-@end itemize
-
-@node The Master Zone
-@subsection The Master Zone
-
-
-The master zone is your personal TLD. Names within the @code{.gnu}
-namespace are resolved relative to this zone. You can arbitrarily
-add records to this zone and selectively publish those records.
-
-@node The Private Zone
-@subsection The Private Zone
-
-
-The private zone is a subzone (or subdomain in DNS terms) of your
-master zone. It should be used for records that you want to keep
-private. For example @code{bank.private.gnu}. The key idea is that
-you want to keep your private records separate, if just to know
-that those names are not available to other users.
-
-@node The Shorten Zone
-@subsection The Shorten Zone
-
-
-The shorten zone can either be a subzone of the master zone or the
-private zone. It is different from the other zones in that GNS
-will automatically populate this zone with other users' zones based
-on their PSEU records whenever you resolve a name.
-
-For example if you go to
-@code{@uref{http://www.bob.alice.dave.gnu/, www.bob.alice.dave.gnu}},
-GNS will try to import @code{bob} into your shorten zone. Having
-obtained Bob's PKEY from @code{alice.dave.gnu}, GNS will lookup the
-PSEU record for @code{+} in Bob's zone. If it exists and the specified
-pseudonym is not taken, Bob's PKEY will be automatically added under
-that pseudonym (i.e. "bob") into your shorten zone. From then on,
-Bob's webpage will also be available for you as
-@code{@uref{http://www.bob.short.gnu/, www.bob.short.gnu}}.
-This feature is called @b{automatic name shortening} and is supposed to
-keep GNS names as short and memorable as possible.
-
-@node The ZKEY Top Level Domain in GNS
-@subsection The ZKEY Top Level Domain in GNS
-
-
-GNS also provides a secure and globally unique namespace under the .zkey
-top-level domain. A name in the .zkey TLD corresponds to the (printable)
-public key of a zone. Names in the .zkey TLD are then resolved by querying
-the respective zone. The .zkey TLD is 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 @code{.gnu} name.
-
-GNS currently supports the following record types:
-
-@menu
-* NICK::
-* PKEY::
-* BOX::
-* LEHO::
-* VPN::
-* A AAAA and TXT::
-* CNAME::
-* GNS2DNS::
-* 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 name "+" 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.
-
-@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 me '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 (i.e. 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 (virtiual 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 A AAAA and TXT
-@subsubsection A AAAA and TXT
-
-Those records work in exactly the same fashion as in traditional DNS.
-
-@node CNAME
-@subsubsection CNAME
-
-As specified in RFC 1035 whenever a CNAME is encountered the query
-needs to be restarted with the specified name. In GNS a CNAME
-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, i.e.
-
-@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 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.
-
-@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
-(i.e. 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 (i.e. '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
-specfiy the desired address family of the result (i.e. "-4"), and the
-intended target IP on the Internet ("-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.
diff --git a/doc/chapters/vocabulary.texi b/doc/chapters/vocabulary.texi
deleted file mode 100644
index 8b6cbe35a..000000000
--- a/doc/chapters/vocabulary.texi
+++ /dev/null
@@ -1,47 +0,0 @@
-@node Vocabulary
-@chapter Vocabulary
-
-@menu
-* Words and characters::
-* Technical Assumptions::
-@end menu
-
-@node Words and characters
-@section Words and characters
-
-Throughout this document we use certain words and characters.
-
-@enumerate
-@item
-``@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.