/* 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 /** * Method called from PSYC upon receiving a message indicating a call * to a '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) * @param data_size number of bytes in 'data' * @param data data stream given to the method (might not be zero-terminated * if data is binary) */ 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, size_t data_size, const char *data); /** * Handle for the channel of a PSYC group. */ struct GNUNET_PSYC_Channel; /** * Start a PSYC channel. Will create a multicast group identified by * the given public key. Messages recevied 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 parent parent channel, NULL for top-level channels * @param name name of the channel, only important if this is a subchannel * @param method_count number of methods in 'methods' array * @param methods functions to invoke on messages received from members, * typcially at least contains functions for 'join' and 'leave'. * @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_start (const struct GNUNET_CONFIGURATION_Handle *cfg, struct GNUNET_PSYC_Channel *parent, const char *name, unsigned int method_count, const struct GNUNET_PSYC_Method *methods, 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 'SET' with emtpy 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 variables. 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_broadcast_call_method'. * 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_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 initially set to the number of bytes available in 'data', * should be set to the number of bytes written to data (IN/OUT) * @param data where to write the body of the message to give to the method; * function must copy at most '*data_size' bytes to '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 'data_size' was not big enough to take all the data) * GNUNET_OK 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, char *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 * (and all parent channels if this is a subchannel). * * @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 '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); /** * End a PSYC channel. Note that subchannels MUST be ended before * their parents. * * @param channel PSYC channel to terminate */ void GNUNET_PSYC_channel_end (struct GNUNET_PSYC_Channel *channel); /** * Handle to access PSYC group operations for all members. */ struct GNUNET_PSYC_Group; /** * Convert 'channel' to a 'group' handle to access the 'group' APIs. * * @param channel channel handle * @return group handle, valid for as long as 'channel' is valid */ struct GNUNET_PSYC_Group * GNUNET_PSYC_channel_get_group (struct GNUNET_PSYC_Channel *channel); /** * 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 'join' message to notify other group members * and they then also must still call this function in their respective * methods handling the 'join' message. This way, how 'join' and 'leave' * operations are exactly implemented is still up to the application; * for example, there might be a '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_admit (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 'leave' message to notify other group members * and they then also must still call this function in their respective * methods handling the 'leave' message. This way, how 'join' and 'leave' * operations are exactly implemented is still up to the application; * for example, there might be a '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_kick (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 */ typedef void (*GNUNET_PSYC_StateCallback)(void *cls, const char *full_state_name, enum GNUNET_PSYC_Operator type, const struct GNUNET_PSYC_Argument *state_value); /** * Descriptor for an event handler handling PSYC state updates. */ struct GNUNET_PSYC_StateHandler { /** * Name of the state 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 'event_handler' function. */ void *event_handler_cls; /** * Description of the kind of state that the handler expects to see. * Non-matching state updates will be ignored (but logged). Note * that the state_types of all states with the same state name * prefix should be identical. For state types, the * 'GNUNET_PSYC_AF_STREAMABLE' and 'GNUNET_PSYC_AF_SET_STREAMABLE' * flags must never be set (as the channel state should be small * enough to (easily) fit into the memory of all PSYC members). */ struct GNUNET_PSYC_ArgumentDescriptor state_type; }; /** * Join a PSYC group. The entity joining is always the local peer. * This will send a 'join_msg' to the channel; if it succeeds, the * channel state (and 'recent' method calls) will be replayed to the * joining member and the 'join' method will be invoked to show that * we joined successfully. 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_count number of methods in 'methods' array * @param methods functions to invoke on messages received from the channel, * typcially at least contains functions for 'join' and 'leave'. * @param state_count number of state handlers * @param state_handlers array of state event handlers * @param join_msg which method should we invoke on the channel controller * to try to join the channel (i.e. "join") * @param join_cb method to invoke on channel to obtain arguments * for a join method invocation; * use NULL to send nothing (useful for anonymous groups that permit anyone); * arguments to give to join method, must not include streaming args * @param join_cb_cls closure for 'join_cb' * @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, unsigned int method_count, const struct GNUNET_PSYC_Method *methods, unsigned int state_count, struct GNUNET_PSYC_StateHandler *state_handlers, const char *join_method, const struct GNUNET_PSYC_ChannelReadyNotify join_cb, void *join_cb_cls); /** * Function called to provide data for a transmission to the channel * owner (aka the '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 initially set to the number of bytes available in 'data', * should be set to the number of bytes written to data (IN/OUT) * @param data where to write the body of the message to give to the method; * function must copy at most '*data_size' bytes to 'data'. * @return GNUNET_SYSERR on error (fatal, aborts transmission) * GNUNET_NO on success, if more data is to be transmitted later * GNUNET_OK if this completes the transmission (all data supplied) */ typedef int (*GNUNET_PSYC_HostReadyNotify)(void *cls, size_t *data_size, char *data); /** * Handle for a pending PSYC transmission operation. */ struct GNUNET_PSYC_HostTransmitHandle; /** * Request a message to be send to the channel. * * @param member membership handle * @param request_data which method should be invoked on channel (and how) * @param method_name which method should be invoked * @param argc number of arguments the method takes (size of 'ads' array) * @param ads description of the arguments the method takes * @param notify function to call to obtain the arguments * @param notify_cls closure for 'notify' * @return transmission handle, NULL on error (i.e. more than one request queued) */ struct GNUNET_PSYC_HostTransmitHandle * GNUNET_PSYC_member_send_to_host (struct GNUNET_PSYC_Member *member, const char *method_name, GNUNET_PSYC_HostReadyNotify notify, void *notify_cls); /** * Abort transmission request to host. * * @param th handle of the request that is being aborted */ void GNUNET_PSYC_member_send_to_host_cancel (struct GNUNET_PSYC_HostTransmitHandle *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 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, 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 state callback on all matching states 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). * * @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 'cb' * @return message ID for which the state was returned (last seen * message ID) */ uint64_t GNUNET_PSYC_member_state_get (struct GNUNET_PSYC_Member *member, const char *state_name, GNUNET_PSYC_StateCallback cb, void *cb_cls); /** * Obtain the current value of a variable. This function should only * be called during a GNUNET_PSYC_Method invocation (and even then * only if the origin is the state owner), as variables are only valid * for the duration of a method invocation. If this function is * called outside of the scope of such a method invocation, it will * return NULL. * * FIXME: do variables have a hierarchy as well? If so, * we should document the lookup semantics. * * @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, pointer to variable state otherwise */ const char * GNUNET_PSYC_member_variable_get (struct GNUNET_PSYC_Member *member, const char *variable_name, size_t *return_value_size); /** * Leave a multicast group. Will terminate the connection to the PSYC * service. Polite clients should first explicitly send a 'leave' * request (via 'GNUNET_PSYC_member_send_to_host'). This function * must not be called on a 'member' that was obtained from * GNUNET_PSYC_channel_get_group. * * @param member membership handle */ void GNUNET_PSYC_member_leave (struct GNUNET_PSYC_Member *member); #if 0 /* keep Emacsens' auto-indent happy */ { #endif #ifdef __cplusplus } #endif /* ifndef GNUNET_PSYC_SERVICE_H */ #endif /* end of gnunet_psyc_service.h */