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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 = GNUNET_MULTICAST_MESSAGE_FIRST_FRAGMENT,
107 * Last fragment of a message.
109 GNUNET_PSYC_MESSAGE_LAST_FRAGMENT = GNUNET_MULTICAST_MESSAGE_LAST_FRAGMENT,
112 * OR'ed flags if message is not fragmented.
114 GNUNET_PSYC_MESSAGE_NOT_FRAGMENTED = GNUNET_MULTICAST_MESSAGE_NOT_FRAGMENTED
119 * Handle that identifies a join request.
121 * Used to match calls to #GNUNET_PSYC_JoinCallback to the
122 * corresponding calls to GNUNET_PSYC_join_decision().
124 struct GNUNET_PSYC_JoinHandle;
127 * Handle that identifies a part request.
129 * Used to match calls to #GNUNET_PSYC_PartCallback to the
130 * corresponding calls to GNUNET_PSYC_part_ack().
132 struct GNUNET_PSYC_PartHandle;
136 * Method called from PSYC upon receiving a message indicating a call
139 * @param cls Closure.
140 * @param sender Who transmitted the message (master, except for messages
141 * from one of the slaves to the master).
142 * @param message_id Unique message counter for this message;
143 * (unique only in combination with the given sender for
145 * @param method_name Original method name from PSYC (may be more
146 * specific than the registered method name due to try-and-slice matching).
147 * FIXME: no try-and-slice for methods defined here.
148 * @param header_length Number of modifiers in header.
149 * @param header Modifiers present in the message. FIXME: use environment instead?
150 * @param data_offset Byte offset of @a data in the overall data of the method.
151 * @param data_size Number of bytes in @a data.
152 * @param data Data stream given to the method (might not be zero-terminated
153 * if data is binary).
154 * @param frag Fragmentation status for the data.
156 typedef int (*GNUNET_PSYC_Method)(void *cls,
157 const struct GNUNET_PeerIdentity *sender,
159 const char *method_name,
160 size_t header_length,
161 GNUNET_PSYC_Modifier *header,
162 uint64_t data_offset,
165 enum GNUNET_PSYC_MessageFlags flags);
169 * Method called from PSYC upon receiving a join request.
171 * @param cls Closure.
172 * @param peer Peer requesting to join.
173 * @param method_name Method name in the join request.
174 * @param header_length Number of modifiers in header.
175 * @param header Modifiers present in the message.
176 * @param data_size Number of bytes in @a data.
177 * @param data Data stream given to the method (might not be zero-terminated
178 * if data is binary).
180 typedef int (*GNUNET_PSYC_JoinCallback)(void *cls,
181 const struct GNUNET_PeerIdentity *peer,
182 const char *method_name,
183 size_t header_length,
184 GNUNET_PSYC_Modifier *header,
187 struct GNUNET_PSYC_JoinHandle *jh);
191 * Method called from PSYC upon receiving a part request.
193 * @param cls Closure.
194 * @param peer Peer requesting to leave.
195 * @param method_name Method name in the part request.
196 * @param header_length Number of modifiers in header.
197 * @param header Modifiers present in the message.
198 * @param data_size Number of bytes in @a data.
199 * @param data Data stream given to the method (might not be zero-terminated
200 * if data is binary).
202 typedef int (*GNUNET_PSYC_PartCallback)(void *cls,
203 const struct GNUNET_PeerIdentity *peer,
204 const char *method_name,
205 size_t header_length,
206 GNUNET_PSYC_Modifier *header,
209 struct GNUNET_PSYC_PartHandle *ph);
213 * Function to call with the decision made for a join request.
215 * Must be called once and only once in response to an invocation of the
216 * #GNUNET_PSYC_JoinCallback.
218 * @param jh Join request handle.
219 * @param is_admitted #GNUNET_YES if joining is approved,
220 * #GNUNET_NO if it is disapproved
221 * @param method_name Method name for the message transmitted with the response.
222 * @param env Environment: transient variables for the message.
223 * @param data_size Size of @a data.
224 * @param data Data of the message.
227 GNUNET_PSYC_join_decision (struct GNUNET_PSYC_JoinHandle *jh,
229 const char *method_name,
230 const struct GNUNET_ENV_Environment *env,
236 * Send a part acknowledgment.
238 * @param ph Part handle.
241 GNUNET_PSYC_part_ack (struct GNUNET_PSYC_PartHandle *ph);
245 * Handle for the master of a PSYC channel.
247 struct GNUNET_PSYC_Master;
251 * Create a PSYC channel master.
253 * Will create a multicast group identified by the given ECC key. Messages
254 * received from group members will be given to the respective handler methods.
255 * If a new member wants to join a group, the "join" method handler will be
256 * invoked; the join handler must then generate a "join" message to approve the
257 * joining of the new member. The channel can also change group membership
258 * without explicit requests. Note that PSYC doesn't itself "understand" join
259 * or part messages, the respective methods must call other PSYC functions to
260 * inform PSYC about the meaning of the respective events.
262 * @param cfg Configuration to use (to connect to PSYC service).
263 * @param priv_key ECC key that will be used to sign messages for this
264 * PSYC session; public key is used to identify the
265 * PSYC channel; FIXME: we'll likely want to use
266 * NOT the p512 curve here, but a cheaper one in the future
267 * Note that end-users will usually not use the private key
268 * directly, but rather look it up in GADS for places
269 * managed by other users, or select a file with the private
270 * key(s) when setting up their own channels
271 * @param join_policy What is the membership policy of the group?
272 * Used to automate group management decisions.
273 * @param method_cb Function to invoke on messages received from members.
274 * @param join_cb Function to invoke when a peer wants to join.
275 * @param part_cb Function to invoke when a peer wants to part.
276 * @param cls Closure for the callbacks.
277 * @return Handle for the channel master, NULL on error.
279 struct GNUNET_PSYC_Master *
280 GNUNET_PSYC_master_create (const struct GNUNET_CONFIGURATION_Handle *cfg,
281 const struct GNUNET_CRYPTO_EccPrivateKey *priv_key,
282 enum GNUNET_MULTICAST_JoinPolicy join_policy,
283 GNUNET_PSYC_Method method_cb,
284 GNUNET_PSYC_JoinCallback join_cb,
285 GNUNET_PSYC_PartCallback part_cb,
290 * Function called to provide data for a transmission via PSYC.
292 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
293 * invalidates the respective transmission handle.
295 * @param cls Closure.
296 * @param message_id Set to the unique message ID that was generated for
298 * @param data_size[in,out] Initially set to the number of bytes available in @a data,
299 * should be set to the number of bytes written to data (IN/OUT).
300 * @param[out] data Where to write the body of the message to give to the method;
301 * function must copy at most @a *data_size bytes to @a data.
302 * @return #GNUNET_SYSERR on error (fatal, aborts transmission)
303 * #GNUNET_NO on success, if more data is to be transmitted later
304 * (should be used if @a *data_size was not big enough to take all the data)
305 * #GNUNET_YES if this completes the transmission (all data supplied)
307 typedef int (*GNUNET_PSYC_MasterReadyNotify)(void *cls,
314 * Handle for a pending PSYC transmission operation.
316 struct GNUNET_PSYC_MasterTransmitHandle;
320 * Send a message to call a method to all members in the PSYC channel.
322 * @param master Handle to the PSYC channel.
323 * @param increment_group_generation #GNUNET_YES if we need to increment
324 * the group generation counter after transmitting this message.
325 * @param method_name Which method should be invoked.
326 * @param env Environment: state operations and transient variables for the message.
327 * @param notify Function to call to obtain the arguments.
328 * @param notify_cls Closure for @a notify.
329 * @return Transmission handle, NULL on error (i.e. more than one request queued).
331 struct GNUNET_PSYC_MasterTransmitHandle *
332 GNUNET_PSYC_master_transmit (struct GNUNET_PSYC_Master *master,
333 int increment_group_generation,
334 const char *method_name,
335 const struct GNUNET_ENV_Environment *env,
336 GNUNET_PSYC_MasterReadyNotify notify,
341 * Abort transmission request to channel.
343 * @param th Handle of the request that is being aborted.
346 GNUNET_PSYC_master_transmit_cancel (struct GNUNET_PSYC_MasterTransmitHandle *th);
350 * Destroy a PSYC channel master.
352 * @param master PSYC channel master to terminate.
355 GNUNET_PSYC_master_destroy (struct GNUNET_PSYC_Master *master);
359 * Handle to access PSYC channel operations for both the master and slaves.
361 struct GNUNET_PSYC_Channel;
365 * Convert a channel @a master to a @e channel handle to access the @e channel APIs.
367 * @param master Channel master handle.
368 * @return Channel handle, valid for as long as @a master is valid.
370 struct GNUNET_PSYC_Channel *
371 GNUNET_PSYC_master_get_channel (struct GNUNET_PSYC_Master *master);
375 * Convert @a slave to a @e channel handle to access the @e channel APIs.
377 * @param slave Slave handle.
378 * @return Channel handle, valid for as long as @a slave is valid.
380 struct GNUNET_PSYC_Channel *
381 GNUNET_PSYC_slave_get_channel (struct GNUNET_PSYC_Slave *slave);
385 * Add a member to the channel.
387 * Note that this will NOT generate any PSYC traffic, it will merely update the
388 * local data base to modify how we react to <em>membership test</em> queries.
389 * The channel master still needs to explicitly transmit a @e join message to
390 * notify other channel members and they then also must still call this function
391 * in their respective methods handling the @e join message. This way, how @e
392 * join and @e part operations are exactly implemented is still up to the
393 * application; for example, there might be a @e part_all method to kick out
396 * Note that channel members are explicitly trusted to execute such methods
397 * correctly; not doing so correctly will result in either denying members
398 * access or offering access to channel data to non-members.
400 * @param channel Channel handle.
401 * @param member Which peer to add.
402 * @param message_id Message ID for the message that changed the membership.
405 GNUNET_PSYC_channel_member_add (struct GNUNET_PSYC_Channel *channel,
406 const struct GNUNET_PeerIdentity *member,
407 uint64_t message_id);
411 * Remove a member from the channel.
413 * Note that this will NOT generate any PSYC traffic, it will merely update the
414 * local data base to modify how we react to <em>membership test</em> queries.
415 * The channel master still needs to explicitly transmit a @e part message to
416 * notify other channel members and they then also must still call this function
417 * in their respective methods handling the @e part message. This way, how
418 * @e join and @e part operations are exactly implemented is still up to the
419 * application; for example, there might be a @e part_all message to kick out
422 * Note that channel members are explicitly trusted to perform these
423 * operations correctly; not doing so correctly will result in either
424 * denying members access or offering access to channel data to
427 * @param channel Channel handle.
428 * @param member Which peer to remove.
429 * @param message_id Message ID for the message that changed the membership.
432 GNUNET_PSYC_channel_member_remove (struct GNUNET_PSYC_Channel *channel,
433 const struct GNUNET_PeerIdentity *member,
434 uint64_t message_id);
438 * Function called to inform a member about stored state values for a channel.
440 * @param cls Closure.
441 * @param name Name of the state variable.
442 * @param value Value of the state variable.
443 * @param value_size Number of bytes in @a value.
445 typedef void (*GNUNET_PSYC_StateCallback)(void *cls,
452 * Handle for a PSYC channel slave.
454 struct GNUNET_PSYC_Slave;
458 * Join a PSYC channel.
460 * The entity joining is always the local peer. The user must immediately use
461 * the GNUNET_PSYC_slave_to_master() functions to transmit a @e join_msg to the
462 * channel; if the join request succeeds, the channel state (and @e recent
463 * method calls) will be replayed to the joining member. There is no explicit
464 * notification on failure (as the channel may simply take days to approve,
465 * and disapproval is simply being ignored).
467 * @param cfg Configuration to use.
468 * @param pub_key ECC key that identifies the channel we wish to join.
469 * @param origin Peer identity of the origin.
470 * @param method Function to invoke on messages received from the channel,
471 * typically at least contains functions for @e join and @e part.
472 * @param method_cls Closure for @a method.
473 * @return Handle for the slave, NULL on error.
475 struct GNUNET_PSYC_Slave *
476 GNUNET_PSYC_slave_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
477 const struct GNUNET_CRYPTO_EccPublicKey *pub_key,
478 const struct GNUNET_PeerIdentity *origin,
479 GNUNET_PSYC_Method method,
484 * Part a PSYC channel.
486 * Will terminate the connection to the PSYC service. Polite clients should
487 * first explicitly send a @e part request (via GNUNET_PSYC_slave_to_master()).
489 * @param slave Slave handle.
492 GNUNET_PSYC_slave_part (struct GNUNET_PSYC_Slave *slave);
496 * Function called to provide data for a transmission to the channel
497 * master (aka the @e host of the channel).
499 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
500 * invalidates the respective transmission handle.
502 * @param cls Closure.
503 * @param data_size[in,out] Initially set to the number of bytes available in @a data,
504 * should be set to the number of bytes written to data (IN/OUT).
505 * @param[out] data Where to write the body of the message to give to the method;
506 * function must copy at most @a *data_size bytes to @a data.
507 * @return #GNUNET_SYSERR on error (fatal, aborts transmission).
508 * #GNUNET_NO on success, if more data is to be transmitted later.
509 * #GNUNET_YES if this completes the transmission (all data supplied).
511 typedef int (*GNUNET_PSYC_SlaveReadyNotify)(void *cls,
517 * Handle for a pending PSYC transmission operation.
519 struct GNUNET_PSYC_SlaveTransmitHandle;
523 * Request a message to be sent to the channel master.
525 * @param slave Slave handle.
526 * @param method_name Which (PSYC) method should be invoked (on host).
527 * @param env Environment: transient variables for the message.
528 * @param notify Function to call when we are allowed to transmit (to get data).
529 * @param notify_cls Closure for @a notify.
530 * @return Transmission handle, NULL on error (i.e. more than one request queued).
532 struct GNUNET_PSYC_SlaveTransmitHandle *
533 GNUNET_PSYC_slave_transmit (struct GNUNET_PSYC_Slave *slave,
534 const char *method_name,
535 const struct GNUNET_ENV_Environment *env,
536 GNUNET_PSYC_SlaveReadyNotify notify,
541 * Abort transmission request to master.
543 * @param th Handle of the request that is being aborted.
546 GNUNET_PSYC_slave_transmit_cancel (struct GNUNET_PSYC_SlaveTransmitHandle *th);
550 * Handle to a story telling operation.
552 struct GNUNET_PSYC_Story;
556 * Request to be told the message history of the channel.
558 * Historic messages (but NOT the state at the time) will be replayed (given to
559 * the normal method handlers) if available and if access is permitted.
561 * To get the latest message, use 0 for both the start and end message ID.
563 * @param slave Which channel should be replayed?
564 * @param start_message_id Earliest interesting point in history.
565 * @param end_message_id Last (exclusive) interesting point in history.
566 * @param method Function to invoke on messages received from the story.
567 * @param method_cls Closure for @a method.
568 * @param finish_cb Function to call when the requested story has been fully
569 * told (counting message IDs might not suffice, as some messages
570 * might be secret and thus the listener would not know the story is
571 * finished without being told explicitly); once this function
572 * has been called, the client must not call
573 * GNUNET_PSYC_slave_story_tell_cancel() anymore.
574 * @param finish_cb_cls Closure to finish_cb.
575 * @return Handle to cancel story telling operation.
577 struct GNUNET_PSYC_Story *
578 GNUNET_PSYC_slave_story_tell (struct GNUNET_PSYC_Slave *slave,
579 uint64_t start_message_id,
580 uint64_t end_message_id,
581 GNUNET_PSYC_Method method,
583 void (*finish_cb)(void *),
584 void *finish_cb_cls);
588 * Abort story telling.
590 * This function must not be called from within method handlers (as given to
591 * GNUNET_PSYC_slave_join()) of the slave.
593 * @param story Story telling operation to stop.
596 GNUNET_PSYC_slave_story_tell_cancel (struct GNUNET_PSYC_Story *story);
600 * Call the given callback on all matching values (including variables) in the
603 * The callback is invoked synchronously on all matching states (as the state is
604 * fully replicated in the library in this process; channel states should be
605 * small, large data is to be passed as streaming data to methods).
607 * A name matches if it includes the @a state_name prefix, thus requesting the
608 * empty state ("") will match all values; requesting "_a_b" will also return
609 * values stored under "_a_b_c".
611 * @param slave Slave handle.
612 * @param state_name Name of the state to query (full name
613 * might be longer, this is only the prefix that must match).
614 * @param cb Function to call on the matching state values.
615 * @param cb_cls Closure for @a cb.
616 * @return Message ID for which the state was returned (last seen
620 GNUNET_PSYC_slave_state_get_all (struct GNUNET_PSYC_Slave *slave,
621 const char *state_name,
622 GNUNET_PSYC_StateCallback cb,
627 * Obtain the current value of the best-matching value in the state
628 * (including variables).
630 * Note that variables are only valid during a #GNUNET_PSYC_Method invocation, as
631 * variables are only valid for the duration of a method invocation.
633 * If the requested variable name does not have an exact state in
634 * the state, the nearest less-specific name is matched; for example,
635 * requesting "_a_b" will match "_a" if "_a_b" does not exist.
637 * @param slave Slave handle.
638 * @param variable_name Name of the variable to query.
639 * @param[out] return_value_size Set to number of bytes in variable,
640 * needed as variables might contain binary data and
641 * might also not be 0-terminated; set to 0 on errors.
642 * @return NULL on error (no matching state or variable), pointer
643 to the respective value otherwise.
646 GNUNET_PSYC_slave_state_get (struct GNUNET_PSYC_Slave *slave,
647 const char *variable_name,
648 size_t *return_value_size);
651 #if 0 /* keep Emacsens' auto-indent happy */
658 /* ifndef GNUNET_PSYC_SERVICE_H */
660 /* end of gnunet_psyc_service.h */