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22 * @file include/gnunet_psyc_service.h
23 * @brief PSYC service; high-level access to the PSYC protocol
24 * note that clients of this API are NOT expected to
25 * understand the PSYC message format, only the semantics!
26 * Parsing (and serializing) the PSYC stream format is done
27 * within the implementation of the libgnunetpsyc library,
28 * and this API deliberately exposes as little as possible
29 * of the actual data stream format to the application!
30 * @author Christian Grothoff
31 * @author Gabor X Toth
34 * - this API does not know about psyc's "root" and "places";
35 * there is no 'root' in GNUnet-Psyc as we're decentralized;
36 * 'places' and 'persons' are combined within the same
37 * abstraction, that of a "channel". Channels are identified
38 * and accessed in this API using a public/private key.
39 * Higher-level applications should use NAMES within GADS
40 * to obtain public keys, and the distinction between
41 * 'places' and 'persons' can then be made with the help
42 * of the naming system (and/or conventions).
43 * Channels are (as in PSYC) organized into a hierarchy; each
44 * channel master (the one with the private key) is then
45 * the operator of the multicast group (its Origin in
46 * the terminology of the multicast API).
47 * - The API supports passing large amounts of data using
48 * 'streaming' for the argument passed to a method. State
49 * and variables must fit into memory and cannot be streamed
50 * (thus, no passing of 4 GB of data in a variable;
51 * once we implement this, we might want to create a
52 * @c \#define for the maximum size of a variable).
53 * - PSYC defines standard variables, methods, etc. This
54 * library deliberately abstracts over all of these; a
55 * higher-level API should combine the naming system (GADS)
56 * and standard methods (message, join, part, warn,
57 * fail, error) and variables (action, color, time,
58 * tag, etc.). However, this API does take over the
59 * routing variables, specifically 'context' (channel),
60 * and 'source'. We only kind-of support 'target', as
61 * the target is either everyone in the group or the
62 * origin, and never just a single member of the group;
63 * for such individual messages, an application needs to
64 * construct an 'inbox' channel where the master (only)
65 * receives messages (but never forwards; private responses
66 * would be transmitted by joining the senders 'inbox'
67 * channel -- or a inbox#bob subchannel). The
68 * goal for all of this is to keep the abstractions in this
69 * API minimal: interaction with multicast, try \& slice,
70 * state/variable/channel management. Higher-level
71 * operations belong elsewhere (so maybe this API should
72 * be called 'PSYC-low', whereas a higher-level API
73 * implementing defaults for standard methods and
74 * variables might be called 'PSYC-std' or 'PSYC-high'.
77 #ifndef GNUNET_PSYC_SERVICE_H
78 #define GNUNET_PSYC_SERVICE_H
83 #if 0 /* keep Emacsens' auto-indent happy */
88 #include "gnunet_util_lib.h"
89 #include "gnunet_psyc_lib.h"
90 #include "gnunet_multicast_service.h"
94 * Version number of GNUnet-PSYC API.
96 #define GNUNET_PSYC_VERSION 0x00000000
99 enum GNUNET_PSYC_MessageFlags
102 * First fragment of a message.
104 GNUNET_PSYC_MESSAGE_FIRST_FRAGMENT = 1 << 0,
107 * Last fragment of a message.
109 GNUNET_PSYC_MESSAGE_LAST_FRAGMENT = 1 << 1,
112 * OR'ed flags if message is not fragmented.
114 GNUNET_PSYC_MESSAGE_NOT_FRAGMENTED
115 = GNUNET_PSYC_MESSAGE_FIRST_FRAGMENT
116 | GNUNET_PSYC_MESSAGE_LAST_FRAGMENT,
119 * Historic message, retrieved from PSYCstore.
121 GNUNET_PSYC_MESSAGE_HISTORIC = 1 << 30
126 * Handle that identifies a join request.
128 * Used to match calls to #GNUNET_PSYC_JoinCallback to the
129 * corresponding calls to GNUNET_PSYC_join_decision().
131 struct GNUNET_PSYC_JoinHandle;
135 * Method called from PSYC upon receiving a message indicating a call
138 * @param cls Closure.
139 * @param slave_key Who transmitted the message.
140 * - NULL for multicast messages from the master.
141 * - The hash of the sending slave's public key for unicast requests from
142 * one of the slaves to the master.
143 * @param message_id Unique message counter for this message.
144 * Unique only in combination with the given sender for this channel.
145 * @param method_name Method name from PSYC.
146 * @param modifier_count Number of elements in the @a modifiers array.
147 * @param modifiers State modifiers and transient variables for the message.
148 * @param data_offset Byte offset of @a data in the overall data of the method.
149 * @param data_size Number of bytes in @a data.
150 * @param data Data stream given to the method (might not be zero-terminated
151 * if data is binary).
152 * @param frag Fragmentation status for the data.
155 (*GNUNET_PSYC_Method) (void *cls,
156 const struct GNUNET_CRYPTO_EccPublicKey *slave_key,
158 const char *method_name,
159 size_t modifier_count,
160 const GNUNET_ENV_Modifier *modifiers,
161 uint64_t data_offset,
164 enum GNUNET_PSYC_MessageFlags flags);
168 * Method called from PSYC upon receiving a join request.
170 * @param cls Closure.
171 * @param slave requesting to join.
172 * @param method_name Method name in the join request.
173 * @param variable_count Number of elements in the @a variables array.
174 * @param variables Transient variables for the join request.
175 * @param data_size Number of bytes in @a data.
176 * @param data Data stream given to the method (might not be zero-terminated
177 * if data is binary).
180 (*GNUNET_PSYC_JoinCallback) (void *cls,
181 const struct GNUNET_CRYPTO_EccPublicKey *slave_key,
182 const char *method_name,
183 size_t variable_count,
184 const GNUNET_ENV_Modifier *variables,
187 struct GNUNET_PSYC_JoinHandle *jh);
191 * Function to call with the decision made for a join request.
193 * Must be called once and only once in response to an invocation of the
194 * #GNUNET_PSYC_JoinCallback.
196 * @param jh Join request handle.
197 * @param is_admitted #GNUNET_YES if joining is approved,
198 * #GNUNET_NO if it is disapproved.
199 * @param relay_count Number of relays given.
200 * @param relays Array of suggested peers that might be useful relays to use
201 * when joining the multicast group (essentially a list of peers that
202 * are already part of the multicast group and might thus be willing
203 * to help with routing). If empty, only this local peer (which must
204 * be the multicast origin) is a good candidate for building the
205 * multicast tree. Note that it is unnecessary to specify our own
206 * peer identity in this array.
207 * @param method_name Method name for the message transmitted with the response.
208 * @param env Environment containing transient variables for the message, or NULL.
209 * @param data_size Size of @a data.
210 * @param data Data of the message.
213 GNUNET_PSYC_join_decision (struct GNUNET_PSYC_JoinHandle *jh,
215 unsigned int relay_count,
216 const struct GNUNET_PeerIdentity *relays,
217 const char *method_name,
218 const struct GNUNET_ENV_Environment *env,
224 * Handle for the master of a PSYC channel.
226 struct GNUNET_PSYC_Master;
230 * Start a PSYC master channel.
232 * Will start a multicast group identified by the given ECC key. Messages
233 * received from group members will be given to the respective handler methods.
234 * If a new member wants to join a group, the "join" method handler will be
235 * invoked; the join handler must then generate a "join" message to approve the
236 * joining of the new member. The channel can also change group membership
237 * without explicit requests. Note that PSYC doesn't itself "understand" join
238 * or part messages, the respective methods must call other PSYC functions to
239 * inform PSYC about the meaning of the respective events.
241 * @param cfg Configuration to use (to connect to PSYC service).
242 * @param channel_key ECC key that will be used to sign messages for this
243 * PSYC session. The public key is used to identify the PSYC channel.
244 * Note that end-users will usually not use the private key directly, but
245 * rather look it up in GADS for places managed by other users, or select
246 * a file with the private key(s) when setting up their own channels
247 * FIXME: we'll likely want to use NOT the p521 curve here, but a cheaper
249 * @param policy Group policy specifying join and history restrictions.
250 * Used to automate group management decisions.
251 * @param method Function to invoke on messages received from slaves.
252 * @param join_cb Function to invoke when a peer wants to join.
253 * @param cls Closure for @a method and @a join_cb.
254 * @return Handle for the channel master, NULL on error.
256 struct GNUNET_PSYC_Master *
257 GNUNET_PSYC_master_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
258 const struct GNUNET_CRYPTO_EccPrivateKey *channel_key,
259 enum GNUNET_MULTICAST_GroupPolicy policy,
260 GNUNET_PSYC_Method method,
261 GNUNET_PSYC_JoinCallback join_cb,
266 * Function called to provide data for a transmission via PSYC.
268 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
269 * invalidates the respective transmission handle.
271 * @param cls Closure.
272 * @param message_id Set to the unique message ID that was generated for
274 * @param[in,out] data_size Initially set to the number of bytes available in @a data,
275 * should be set to the number of bytes written to data (IN/OUT).
276 * @param[out] data Where to write the body of the message to give to the method;
277 * function must copy at most @a *data_size bytes to @a data.
278 * @return #GNUNET_SYSERR on error (fatal, aborts transmission)
279 * #GNUNET_NO on success, if more data is to be transmitted later
280 * (should be used if @a *data_size was not big enough to take all the data)
281 * #GNUNET_YES if this completes the transmission (all data supplied)
284 (*GNUNET_PSYC_MasterReadyNotify)(void *cls,
291 * Handle for a pending PSYC transmission operation.
293 struct GNUNET_PSYC_MasterTransmitHandle;
297 * Send a message to call a method to all members in the PSYC channel.
299 * @param master Handle to the PSYC channel.
300 * @param method_name Which method should be invoked.
301 * @param env Environment containing state operations and transient variables
302 * for the message, or NULL.
303 * @param notify Function to call to obtain the arguments.
304 * @param notify_cls Closure for @a notify.
305 * @param reset_state #GNUNET_YES if this message should reset the channel
306 * state, i.e. remove all previously stored state variables.
307 * #GNUNET_NO to keep the state as is.
308 * @param increment_group_generation #GNUNET_YES if we need to increment
309 * the group generation counter after transmitting this message.
310 * @return Transmission handle, NULL on error (i.e. more than one request queued).
312 struct GNUNET_PSYC_MasterTransmitHandle *
313 GNUNET_PSYC_master_transmit (struct GNUNET_PSYC_Master *master,
314 const char *method_name,
315 const struct GNUNET_ENV_Environment *env,
316 GNUNET_PSYC_MasterReadyNotify notify,
319 int increment_group_generation);
323 * Abort transmission request to channel.
325 * @param th Handle of the request that is being aborted.
328 GNUNET_PSYC_master_transmit_cancel (struct GNUNET_PSYC_MasterTransmitHandle *th);
332 * Stop a PSYC master channel.
334 * @param master PSYC channel master to stop.
337 GNUNET_PSYC_master_stop (struct GNUNET_PSYC_Master *master);
341 * Handle for a PSYC channel slave.
343 struct GNUNET_PSYC_Slave;
347 * Join a PSYC channel.
349 * The entity joining is always the local peer. The user must immediately use
350 * the GNUNET_PSYC_slave_to_master() functions to transmit a @e join_msg to the
351 * channel; if the join request succeeds, the channel state (and @e recent
352 * method calls) will be replayed to the joining member. There is no explicit
353 * notification on failure (as the channel may simply take days to approve,
354 * and disapproval is simply being ignored).
356 * @param cfg Configuration to use.
357 * @param channel_key ECC public key that identifies the channel we wish to join.
358 * @param slave_key ECC private-public key pair that identifies the slave, and
359 * used by multicast to sign the join request and subsequent unicast
360 * requests sent to the master.
361 * @param origin Peer identity of the origin.
362 * @param relay_count Number of peers in the @a relays array.
363 * @param relays Peer identities of members of the multicast group, which serve
364 * as relays and used to join the group at.
365 * @param method Function to invoke on messages received from the channel,
366 * typically at least contains functions for @e join and @e part.
367 * @param join_cb Function to invoke when a peer wants to join.
368 * @param cls Closure for @a method_cb and @a join_cb.
369 * @param method_name Method name for the join request.
370 * @param env Environment containing transient variables for the request, or NULL.
371 * @param data_size Number of bytes in @a data.
372 * @param data Payload for the join message.
373 * @return Handle for the slave, NULL on error.
375 struct GNUNET_PSYC_Slave *
376 GNUNET_PSYC_slave_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
377 const struct GNUNET_CRYPTO_EccPublicKey *channel_key,
378 const struct GNUNET_CRYPTO_EccPrivateKey *slave_key,
379 const struct GNUNET_PeerIdentity *origin,
381 const struct GNUNET_PeerIdentity *relays,
382 GNUNET_PSYC_Method method,
383 GNUNET_PSYC_JoinCallback join_cb,
385 const char *method_name,
386 const struct GNUNET_ENV_Environment *env,
392 * Part a PSYC channel.
394 * Will terminate the connection to the PSYC service. Polite clients should
395 * first explicitly send a @e part request (via GNUNET_PSYC_slave_to_master()).
397 * @param slave Slave handle.
400 GNUNET_PSYC_slave_part (struct GNUNET_PSYC_Slave *slave);
404 * Function called to provide data for a transmission to the channel
405 * master (aka the @e host of the channel).
407 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
408 * invalidates the respective transmission handle.
410 * @param cls Closure.
411 * @param[in,out] data_size Initially set to the number of bytes available in @a data,
412 * should be set to the number of bytes written to data (IN/OUT).
413 * @param[out] data Where to write the body of the message to give to the method;
414 * function must copy at most @a *data_size bytes to @a data.
415 * @return #GNUNET_SYSERR on error (fatal, aborts transmission).
416 * #GNUNET_NO on success, if more data is to be transmitted later.
417 * #GNUNET_YES if this completes the transmission (all data supplied).
420 (*GNUNET_PSYC_SlaveReadyNotify) (void *cls,
426 * Handle for a pending PSYC transmission operation.
428 struct GNUNET_PSYC_SlaveTransmitHandle;
432 * Request a message to be sent to the channel master.
434 * @param slave Slave handle.
435 * @param method_name Which (PSYC) method should be invoked (on host).
436 * @param env Environment containing transient variables for the message, or NULL.
437 * @param notify Function to call when we are allowed to transmit (to get data).
438 * @param notify_cls Closure for @a notify.
439 * @return Transmission handle, NULL on error (i.e. more than one request queued).
441 struct GNUNET_PSYC_SlaveTransmitHandle *
442 GNUNET_PSYC_slave_transmit (struct GNUNET_PSYC_Slave *slave,
443 const char *method_name,
444 const struct GNUNET_ENV_Environment *env,
445 GNUNET_PSYC_SlaveReadyNotify notify,
450 * Abort transmission request to master.
452 * @param th Handle of the request that is being aborted.
455 GNUNET_PSYC_slave_transmit_cancel (struct GNUNET_PSYC_SlaveTransmitHandle *th);
459 * Handle to access PSYC channel operations for both the master and slaves.
461 struct GNUNET_PSYC_Channel;
465 * Convert a channel @a master to a @e channel handle to access the @e channel APIs.
467 * @param master Channel master handle.
468 * @return Channel handle, valid for as long as @a master is valid.
470 struct GNUNET_PSYC_Channel *
471 GNUNET_PSYC_master_get_channel (struct GNUNET_PSYC_Master *master);
475 * Convert @a slave to a @e channel handle to access the @e channel APIs.
477 * @param slave Slave handle.
478 * @return Channel handle, valid for as long as @a slave is valid.
480 struct GNUNET_PSYC_Channel *
481 GNUNET_PSYC_slave_get_channel (struct GNUNET_PSYC_Slave *slave);
485 * Add a slave to the channel's membership list.
487 * Note that this will NOT generate any PSYC traffic, it will merely update the
488 * local database to modify how we react to <em>membership test</em> queries.
489 * The channel master still needs to explicitly transmit a @e join message to
490 * notify other channel members and they then also must still call this function
491 * in their respective methods handling the @e join message. This way, how @e
492 * join and @e part operations are exactly implemented is still up to the
493 * application; for example, there might be a @e part_all method to kick out
496 * Note that channel slaves are explicitly trusted to execute such methods
497 * correctly; not doing so correctly will result in either denying other slaves
498 * access or offering access to channel data to non-members.
500 * @param channel Channel handle.
501 * @param slave_key Identity of channel slave to add.
502 * @param announced_at ID of the message that announced the membership change.
503 * @param effective_since Addition of slave is in effect since this message ID.
506 GNUNET_PSYC_channel_slave_add (struct GNUNET_PSYC_Channel *channel,
507 const struct GNUNET_CRYPTO_EccPublicKey *slave_key,
508 uint64_t announced_at,
509 uint64_t effective_since);
513 * Remove a slave from the channel's membership list.
515 * Note that this will NOT generate any PSYC traffic, it will merely update the
516 * local database to modify how we react to <em>membership test</em> queries.
517 * The channel master still needs to explicitly transmit a @e part message to
518 * notify other channel members and they then also must still call this function
519 * in their respective methods handling the @e part message. This way, how
520 * @e join and @e part operations are exactly implemented is still up to the
521 * application; for example, there might be a @e part_all message to kick out
524 * Note that channel members are explicitly trusted to perform these
525 * operations correctly; not doing so correctly will result in either
526 * denying members access or offering access to channel data to
529 * @param channel Channel handle.
530 * @param slave_key Identity of channel slave to remove.
531 * @param announced_at ID of the message that announced the membership change.
532 * @param effective_since Removal of slave is in effect since this message ID.
535 GNUNET_PSYC_channel_slave_remove (struct GNUNET_PSYC_Channel *channel,
536 const struct GNUNET_CRYPTO_EccPublicKey *slave_key,
537 uint64_t announced_at,
538 uint64_t effective_since);
542 * Function called to inform a member about stored state values for a channel.
544 * @param cls Closure.
545 * @param name Name of the state variable.
546 * @param value Value of the state variable.
547 * @param value_size Number of bytes in @a value.
550 (*GNUNET_PSYC_StateCallback) (void *cls,
557 * Handle to a story telling operation.
559 struct GNUNET_PSYC_Story;
563 * Request to be told the message history of the channel.
565 * Historic messages (but NOT the state at the time) will be replayed (given to
566 * the normal method handlers) if available and if access is permitted.
568 * To get the latest message, use 0 for both the start and end message ID.
570 * @param channel Which channel should be replayed?
571 * @param start_message_id Earliest interesting point in history.
572 * @param end_message_id Last (exclusive) interesting point in history.
573 * @param method Function to invoke on messages received from the story.
574 * @param method_cls Closure for @a method.
575 * @param finish_cb Function to call when the requested story has been fully
576 * told (counting message IDs might not suffice, as some messages
577 * might be secret and thus the listener would not know the story is
578 * finished without being told explicitly); once this function
579 * has been called, the client must not call
580 * GNUNET_PSYC_channel_story_tell_cancel() anymore.
581 * @param finish_cb_cls Closure to finish_cb.
582 * @return Handle to cancel story telling operation.
584 struct GNUNET_PSYC_Story *
585 GNUNET_PSYC_channel_story_tell (struct GNUNET_PSYC_Channel *channel,
586 uint64_t start_message_id,
587 uint64_t end_message_id,
588 GNUNET_PSYC_Method method,
590 void (*finish_cb)(void *),
591 void *finish_cb_cls);
595 * Abort story telling.
597 * This function must not be called from within method handlers (as given to
598 * GNUNET_PSYC_slave_join()) of the slave.
600 * @param story Story telling operation to stop.
603 GNUNET_PSYC_channel_story_tell_cancel (struct GNUNET_PSYC_Story *story);
607 * Call the given callback on all matching values (including variables) in the
610 * The callback is invoked synchronously on all matching states (as the state is
611 * fully replicated in the library in this process; channel states should be
612 * small, large data is to be passed as streaming data to methods).
614 * A name matches if it includes the @a state_name prefix, thus requesting the
615 * empty state ("") will match all values; requesting "_a_b" will also return
616 * values stored under "_a_b_c".
618 * @param channel Channel handle.
619 * @param state_name Name of the state to query (full name
620 * might be longer, this is only the prefix that must match).
621 * @param cb Function to call on the matching state values.
622 * @param cb_cls Closure for @a cb.
623 * @return Message ID for which the state was returned (last seen
627 GNUNET_PSYC_channel_state_get_all (struct GNUNET_PSYC_Channel *channel,
628 const char *state_name,
629 GNUNET_PSYC_StateCallback cb,
634 * Obtain the current value of the best-matching value in the state
635 * (including variables).
637 * Note that variables are only valid during a #GNUNET_PSYC_Method invocation, as
638 * variables are only valid for the duration of a method invocation.
640 * If the requested variable name does not have an exact state in
641 * the state, the nearest less-specific name is matched; for example,
642 * requesting "_a_b" will match "_a" if "_a_b" does not exist.
644 * @param channel Channel handle.
645 * @param variable_name Name of the variable to query.
646 * @param[out] return_value_size Set to number of bytes in variable,
647 * needed as variables might contain binary data and
648 * might also not be 0-terminated; set to 0 on errors.
649 * @return NULL on error (no matching state or variable), pointer
650 * to the respective value otherwise.
653 GNUNET_PSYC_channel_state_get (struct GNUNET_PSYC_Channel *channel,
654 const char *variable_name,
655 size_t *return_value_size);
658 #if 0 /* keep Emacsens' auto-indent happy */
665 /* ifndef GNUNET_PSYC_SERVICE_H */
667 /* end of gnunet_psyc_service.h */