/*
This file is part of GNUnet.
(C) 2012, 2013 Christian Grothoff (and other contributing authors)
GNUnet is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
by the Free Software Foundation; either version 3, or (at your
option) any later version.
GNUnet is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNUnet; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/
/**
* @file include/gnunet_psyc_service.h
* @brief PSYC service; high-level access to the PSYC protocol
* note that clients of this API are NOT expected to
* understand the PSYC message format, only the semantics!
* Parsing (and serializing) the PSYC stream format is done
* within the implementation of the libgnunetpsyc library,
* and this API deliberately exposes as little as possible
* of the actual data stream format to the application!
* @author Christian Grothoff
*
* NOTE:
* - this API does not know about psyc's "root" and "places";
* there is no 'root' in GNUnet-Psyc as we're decentralized;
* 'places' and 'persons' are combined within the same
* abstraction, that of a "channel". Channels are identified
* and accessed in this API using a public/private key.
* Higher-level applications should use NAMES within GADS
* to obtain public keys, and the distinction between
* 'places' and 'persons' can then be made with the help
* of the naming system (and/or conventions).
* Channels are (as in PSYC) organized into a hierarchy; each
* channel owner (the one with the private key) is then
* the operator of the multicast group (its Origin in
* the terminology of the multicast API).
* - The API supports passing large amounts of data using
* 'streaming' for the argument passed to a method. State
* and variables must fit into memory and cannot be streamed
* (thus, no passing of 4 GB of data in a variable;
* once we implement this, we might want to create a
* #define for the maximum size of a variable).
* - PSYC defines standard variables, methods, etc. This
* library deliberately abstracts over all of these; a
* higher-level API should combine the naming system (GADS)
* and standard methods (message, join, leave, warn,
* fail, error) and variables (action, color, time,
* tag, etc.). However, this API does take over the
* routing variables, specifically 'context' (channel),
* and 'source'. We only kind-of support 'target', as
* the target is either everyone in the group or the
* origin, and never just a single member of the group;
* for such individual messages, an application needs to
* construct an 'inbox' channel where the owner (only)
* receives messages (but never forwards; private responses
* would be transmitted by joining the senders 'inbox'
* channel -- or a inbox#bob subchannel). The
* goal for all of this is to keep the abstractions in this
* API minimal: interaction with multicast, try \& slice,
* state/variable/channel management. Higher-level
* operations belong elsewhere (so maybe this API should
* be called 'PSYC-low', whereas a higher-level API
* implementing defaults for standard methods and
* variables might be called 'PSYC-std' or 'PSYC-high'.
*/
#ifndef GNUNET_PSYC_SERVICE_H
#define GNUNET_PSYC_SERVICE_H
#ifdef __cplusplus
extern "C"
{
#if 0 /* keep Emacsens' auto-indent happy */
}
#endif
#endif
#include "gnunet_util_lib.h"
#include "gnunet_multicast_service.h"
/**
* Version number of GNUnet-PSYC API.
*/
#define GNUNET_PSYC_VERSION 0x00000000
/**
* Information flags for data fragments set via PSYC.
*/
enum GNUNET_PSYC_FragmentStatus
{
/**
* This is the first part of data for the given method call.
*/
GNUNET_PSYC_FS_FIRST = 1,
/**
* This is the last part of data for the given method call.
*/
GNUNET_PSYC_FS_LAST = 2,
/**
* OR'ed flags if payload is not fragmented.
*/
GNUNET_PSYC_FS_NOT_FRAGMENTED = (GNUNET_PSYC_FS_FIRST | GNUNET_PSYC_FS_LAST)
};
/**
* Method called from PSYC upon receiving a message indicating a call
* to a @e method.
*
* @param cls Closure.
* @param full_method_name Original method name from PSYC (may be more
* specific than the registered method name due to try-and-slice matching).
* @param sender Who transmitted the message (origin, except for messages
* from one of the members to the origin).
* @param message_id Unique message counter for this message;
* (unique only in combination with the given sender for
* this channel).
* @param group_generation Group generation counter for this message
* (always zero for messages from members to channel owner); FIXME: needed?
* @param data_off Byte offset of @a data in the overall data of the method.
* @param data_size Number of bytes in @a data.
* @param data Data stream given to the method (might not be zero-terminated
* if data is binary).
* @param frag Fragmentation status for the data.
*/
typedef int (*GNUNET_PSYC_Method)(void *cls,
const char *full_method_name,
const struct GNUNET_PeerIdentity *sender,
uint64_t message_id,
uint64_t group_generation,
uint64_t data_off,
size_t data_size,
const void *data,
enum GNUNET_PSYC_FragmentStatus frag);
/**
* Handle for the channel of a PSYC group.
*/
struct GNUNET_PSYC_Channel;
/**
* Create a PSYC channel.
*
* Will create a multicast group identified by the given ECC key. Messages
* received from group members will be given to the respective handler methods.
* If a new member wants to join a group, the "join" method handler will be
* invoked; the join handler must then generate a "join" message to approve the
* joining of the new member. The channel can also change group membership
* without explicit requests. Note that PSYC doesn't itself "understand" join
* or leave messages, the respective methods must call other PSYC functions to
* inform PSYC about the meaning of the respective events.
*
* @param cfg Configuration to use (to connect to PSYC service).
* @param method Function to invoke on messages received from members,
* typcially at least contains functions for @e join and @e leave.
* @param method_cls Closure for @a method.
* @param priv_key ECC key that will be used to sign messages for this
* PSYC session; public key is used to identify the
* PSYC group; FIXME: we'll likely want to use
* NOT the p521 curve here, but a cheaper one in the future
* Note that end-users will usually not use the private key
* directly, but rather look it up in GADS for groups
* managed by other users, or select a file with the private
* key(s) when setting up their own channels
* @param join_policy What is the membership policy of the group?
* Used to automate group management decisions.
* @return Handle for the channel, NULL on error.
*/
struct GNUNET_PSYC_Channel *
GNUNET_PSYC_channel_create (const struct GNUNET_CONFIGURATION_Handle *cfg,
GNUNET_PSYC_Method method,
void *method_cls,
const struct GNUNET_CRYPTO_EccPrivateKey *priv_key,
enum GNUNET_MULTICAST_JoinPolicy join_policy);
/**
* Possible operations on PSYC state (persistent) and variables (per message).
*/
enum GNUNET_PSYC_Operator
{
/**
* Replace the full state with the new value ("=").
*/
GNUNET_PSYC_SOT_SET_STATE = 0,
/**
* Delete the complete entry from the state (given data must be
* empty). Equivalent to @a SET with empty data, but more
* explicit ("=");
*/
GNUNET_PSYC_SOT_DELETE = 0,
/**
* Set the value of a variable to a new value (":").
*/
GNUNET_PSYC_SOT_SET_VARIABLE,
/**
* Add the given value to the set of values in the state ("+").
*/
GNUNET_PSYC_SOT_ADD_STATE,
/**
* Remove the given value from the set of values in the state ("-").
*/
GNUNET_PSYC_SOT_REMOVE_STATE
};
/**
* Update channel state (or set a variable).
*
* The state of a channel must fit into the memory of each member (and the
* channel); large values that require streaming must only be passed as the
* stream arguments to methods. State updates might not be transmitted to group
* members until the next call to GNUNET_PSYC_channel_notify_transmit_ready().
* Variable updates must be given just before the call to the respective method
* that needs the variables.
*
* @param channel Handle to the PSYC group / channel.
* @param full_state_name Name of the field in the channel state to change.
* @param type Kind of update operation (add, remove, replace, delete).
* @param data_size Number of bytes in data.
* @param data New state value.
* @return #GNUNET_OK on success, #GNUNET_SYSERR on internal error
* (i.e. state too large).
*/
int
GNUNET_PSYC_channel_state_update (struct GNUNET_PSYC_Channel *channel,
const char *full_state_name,
enum GNUNET_PSYC_Operator type,
size_t data_size,
const void *data);
/**
* Function called to provide data for a transmission via PSYC.
*
* Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
* invalidates the respective transmission handle.
*
* @param cls Closure.
* @param message_id Set to the unique message ID that was generated for
* this message.
* @param group_generation Set to the group generation used for this
* message.
* @param data_size[in,out] Initially set to the number of bytes available in @a data,
* should be set to the number of bytes written to data (IN/OUT).
* @param data[out] Where to write the body of the message to give to the method;
* function must copy at most @a *data_size bytes to @a data.
* @return #GNUNET_SYSERR on error (fatal, aborts transmission)
* #GNUNET_NO on success, if more data is to be transmitted later
* (should be used if @a *data_size was not big enough to take all the data)
* #GNUNET_YES if this completes the transmission (all data supplied)
*/
typedef int (*GNUNET_PSYC_ChannelReadyNotify)(void *cls,
uint64_t message_id,
uint64_t group_generation,
size_t *data_size,
void *data);
/**
* Handle for a pending PSYC transmission operation.
*/
struct GNUNET_PSYC_ChannelTransmitHandle;
/**
* Send a message to call a method to all members in the PSYC channel.
*
* @param channel Handle to the PSYC multicast group.
* @param increment_group_generation #GNUNET_YES if we need to increment
* the group generation counter after transmitting this message.
* @param full_method_name Which method should be invoked.
* @param notify Function to call to obtain the arguments.
* @param notify_cls Closure for @a notify.
* @return Transmission handle, NULL on error (i.e. more than one request queued).
*/
struct GNUNET_PSYC_ChannelTransmitHandle *
GNUNET_PSYC_channel_notify_transmit_ready (struct GNUNET_PSYC_Channel *channel,
int increment_group_generation,
const char *full_method_name,
GNUNET_PSYC_ChannelReadyNotify notify,
void *notify_cls);
/**
* Abort transmission request to channel.
*
* @param th Handle of the request that is being aborted.
*/
void
GNUNET_PSYC_channel_notify_transmit_ready_cancel (struct GNUNET_PSYC_ChannelTransmitHandle *th);
/**
* Destroy a PSYC channel.
*
* @param channel PSYC channel to terminate.
*/
tvoid
GNUNET_PSYC_channel_destroy (struct GNUNET_PSYC_Channel *channel);
/**
* Handle to access PSYC group operations for all members.
*/
struct GNUNET_PSYC_Group;
/**
* Convert @a channel to a @e group handle to access the @e group APIs.
*
* @param channel Channel handle.
* @return Group handle, valid for as long as @a channel is valid.
*/
struct GNUNET_PSYC_Group *
GNUNET_PSYC_channel_get_group (struct GNUNET_PSYC_Channel *channel);
/**
* Convert @a member to a @e group handle to access the @e group APIs.
*
* @param member Membership handle.
* @return Group handle, valid for as long as @a member is valid.
*/
struct GNUNET_PSYC_Group *
GNUNET_PSYC_member_get_group (struct GNUNET_PSYC_Member *member);
/**
* Add a member to the group.
*
* Note that this will NOT generate any PSYC traffic, it will merely update the
* local data base to modify how we react to membership test queries. The
* channel still needs to explicitly transmit a @e join message to notify other
* group members and they then also must still call this function in their
* respective methods handling the @e join message. This way, how @e join and
* @e leave operations are exactly implemented is still up to the application;
* for example, there might be a @e leave_all method to kick out everyone.
*
* Note that group members are explicitly trusted to execute such
* methods correctly; not doing so correctly will result in either
* denying members access or offering access to group data to
* non-members.
*
* @param group Group handle.
* @param member Which peer to add.
* @param message_id Message ID for the message that changed the membership.
* @param group_generation The generation ID where the change went into effect.
*/
void
GNUNET_PSYC_group_member_add (struct GNUNET_PSYC_Group *group,
const struct GNUNET_PeerIdentity *member,
uint64_t message_id,
uint64_t group_generation);
/**
* Remove a member from the group.
*
* Note that this will NOT generate any PSYC traffic, it will merely update the
* local data base to modify how we react to membership test queries. The
* channel still needs to explicitly transmit a @e leave message to notify other
* group members and they then also must still call this function in their
* respective methods handling the @e leave message. This way, how @e join and
* @e leave operations are exactly implemented is still up to the application;
* for example, there might be a @e leave_all message to kick out everyone.
*
* Note that group members are explicitly trusted to perform these
* operations correctly; not doing so correctly will result in either
* denying members access or offering access to group data to
* non-members.
*
* @param group Group handle.
* @param member Which peer to remove.
* @param message_id Message ID for the message that changed the membership.
* @param group_generation The generation ID where the change went into effect.
*/
void
GNUNET_PSYC_group_member_remove (struct GNUNET_PSYC_Group *group,
const struct GNUNET_PeerIdentity *member,
uint64_t message_id,
uint64_t group_generation);
/**
* Function called to inform a member about state changes for a channel.
*
* Note that (for sets) only the delta is communicated, not the full state.
*
* @param cls Closure.
* @param full_state_name Full name of the state.
* @param type How to interpret the change.
* @param state_value Information about the new state.
* @param state_value_size Number of bytes in @a state_value.
*/
typedef void (*GNUNET_PSYC_StateCallback)(void *cls,
const char *full_state_name,
enum GNUNET_PSYC_Operator type,
const void *state_value,
size_t state_value_size);
/**
* Descriptor for an event handler handling PSYC state updates.
*/
struct GNUNET_PSYC_StateHandler
{
/**
* Name of the state variable this handler calls about, used in try-and-slice matching.
*/
const char *state_name;
/**
* Function to call whenever the respective state changes.
*/
GNUNET_PSYC_StateCallback event_handler;
/**
* Closure for the @a event_handler function.
*/
void *event_handler_cls;
};
/**
* Join a PSYC group.
*
* The entity joining is always the local peer. The user must immediately use
* the GNUNET_PSYC_member_send_to_host() (and possibly
* GNUNET_PSYC_member_host_variable_set()) functions to transmit a @e join_msg to
* the channel; if the join request succeeds, the channel state (and @e recent
* method calls) will be replayed to the joining member. There is no explicit
* notification on failure (as the channel may simply take days to approve, and
* disapproval is simply being ignored).
*
* @param cfg Configuration to use.
* @param pub_key ECC key that identifies the channel we wish to join
* @param method Function to invoke on messages received from the channel,
* typically at least contains functions for @e join and @e leave.
* @param method_cls Closure for @a method.
* @param state_count Number of @a state_handlers.
* @param state_handlers Array of state event handlers.
* @return Handle for the member, NULL on error.
*/
struct GNUNET_PSYC_Member *
GNUNET_PSYC_member_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
const struct GNUNET_CRYPTO_EccPublicKey *pub_key,
GNUNET_PSYC_Method method,
void *method_cls,
unsigned int state_count,
struct GNUNET_PSYC_StateHandler *state_handlers);
/**
* Leave a multicast group.
*
* Will terminate the connection to the PSYC service. Polite clients should
* first explicitly send a @e leave request (via
* GNUNET_PSYC_member_send_to_host()).
*
* @param member membership handle
*/
void
GNUNET_PSYC_member_leave (struct GNUNET_PSYC_Member *member);
/**
* Function called to provide data for a transmission to the channel
* owner (aka the @e host of the channel).
*
* Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
* invalidates the respective transmission handle.
*
* @param cls Closure.
* @param data_size[in,out] Initially set to the number of bytes available in @a data,
* should be set to the number of bytes written to data (IN/OUT).
* @param data[out] Where to write the body of the message to give to the method;
* function must copy at most @a *data_size bytes to @a data.
* @return #GNUNET_SYSERR on error (fatal, aborts transmission).
* #GNUNET_NO on success, if more data is to be transmitted later.
* #GNUNET_YES if this completes the transmission (all data supplied).
*/
typedef int (*GNUNET_PSYC_OriginReadyNotify)(void *cls,
size_t *data_size,
char *data);
/**
* Handle for a pending PSYC transmission operation.
*/
struct GNUNET_PSYC_OriginTransmitHandle;
/**
* Request a message to be sent to the channel origin.
*
* @param member Membership handle.
* @param method_name Which (PSYC) method should be invoked (on host).
* @param notify Function to call when we are allowed to transmit (to get data).
* @param notify_cls Closure for @a notify.
* @return Transmission handle, NULL on error (i.e. more than one request queued).
*/
struct GNUNET_PSYC_OriginTransmitHandle *
GNUNET_PSYC_member_send_to_origin (struct GNUNET_PSYC_Member *member,
const char *method_name,
GNUNET_PSYC_OriginReadyNotify notify,
void *notify_cls);
/**
* Set a (temporary, ":") variable for the next message being transmitted
* via GNUNET_PSYC_member_send_to_host().
*
* If GNUNET_PSYC_member_send_to_host() is called and then cancelled, all
* variables that were set using this function will be unset (lost/forgotten).
* To clear a variable state after setting it, you can also call this function
* again with NULL/0 for the @a value.
*
* @param member Membership handle.
* @param variable_name Name of the variable to set.
* @param value Value to set for the given variable.
* @param value_size Number of bytes in @a value.
*/
uint64_t
GNUNET_PSYC_member_origin_variable_set (struct GNUNET_PSYC_Member *member,
const char *variable_name,
const void *value,
size_t value_size);
/**
* Abort transmission request to origin.
*
* @param th Handle of the request that is being aborted.
*/
void
GNUNET_PSYC_member_send_to_origin_cancel (struct GNUNET_PSYC_OriginTransmitHandle *th);
/**
* Handle to a story telling operation.
*/
struct GNUNET_PSYC_Story;
/**
* Request to be told the message history of the channel.
*
* Historic messages (but NOT the state at the time) will be replayed (given to
* the normal method handlers) if available and if access is permitted.
*
* @param member Which channel should be replayed?
* @param start Earliest interesting point in history.
* @param end Last (exclusive) interesting point in history.
* @param method Function to invoke on messages received from the story.
* @param method_cls Closure for @a method.
* @param finish_cb Function to call when the requested story has been fully
* told (counting message IDs might not suffice, as some messages
* might be secret and thus the listener would not know the story is
* finished without being told explicitly); once this function
* has been called, the client must not call
* GNUNET_PSYC_member_story_tell_cancel() anymore.
* @param finish_cb_cls Closure to finish_cb.
* @return Handle to cancel story telling operation.
*/
struct GNUNET_PSYC_Story *
GNUNET_PSYC_member_story_tell (struct GNUNET_PSYC_Member *member,
uint64_t start,
uint64_t end,
GNUNET_PSYC_Method method,
void *method_cls,
void (*finish_cb)(void *),
void *finish_cb_cls);
/**
* Abort story telling.
*
* This function must not be called from within method handlers (as given to
* GNUNET_PSYC_member_join()) of the member.
*
* @param story Story telling operation to stop.
*/
void
GNUNET_PSYC_member_story_tell_cancel (struct GNUNET_PSYC_Story *story);
/**
* Call the given callback on all matching values (including variables) in the
* channel state.
*
* The callback is invoked synchronously on all matching states (as the state is
* fully replicated in the library in this process; channel states should be
* small, large data is to be passed as streaming data to methods).
*
* A name matches if it includes the @a state_name prefix, thus requesting the
* empty state ("") will match all values; requesting "a_b" will also return
* values stored under "a_b_c".
*
* @param member Membership handle.
* @param state_name Name of the state to query (full name
* might be longer, this is only the prefix that must match).
* @param cb Function to call on the matching state values.
* @param cb_cls Closure for @a cb.
* @return Message ID for which the state was returned (last seen
* message ID).
*/
uint64_t
GNUNET_PSYC_member_state_get_all (struct GNUNET_PSYC_Member *member,
const char *state_name,
GNUNET_PSYC_StateCallback cb,
void *cb_cls);
/**
* Obtain the current value of the best-matching value in the state
* (including variables).
*
* Note that variables are only valid during a #GNUNET_PSYC_Method invocation, as
* variables are only valid for the duration of a method invocation.
*
* If the requested variable name does not have an exact state in
* the state, the nearest less-specific name is matched; for example,
* requesting "a_b" will match "a" if "a_b" does not exist.
*
* @param member Membership handle.
* @param variable_name Name of the variable to query.
* @param return_value_size Set to number of bytes in variable,
* needed as variables might contain binary data and
* might also not be 0-terminated; set to 0 on errors.
* @return NULL on error (no matching state or variable), pointer
to the respective value otherwise.
*/
const void *
GNUNET_PSYC_member_state_get (struct GNUNET_PSYC_Member *member,
const char *variable_name,
size_t *return_value_size);
#if 0 /* keep Emacsens' auto-indent happy */
{
#endif
#ifdef __cplusplus
}
#endif
/* ifndef GNUNET_PSYC_SERVICE_H */
#endif
/* end of gnunet_psyc_service.h */