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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;
134 * Handle that identifies a part request.
136 * Used to match calls to #GNUNET_PSYC_PartCallback to the
137 * corresponding calls to GNUNET_PSYC_part_ack().
139 struct GNUNET_PSYC_PartHandle;
143 * Method called from PSYC upon receiving a message indicating a call
146 * @param cls Closure.
147 * @param sender Who transmitted the message (master, except for messages
148 * from one of the slaves to the master).
149 * @param message_id Unique message counter for this message;
150 * (unique only in combination with the given sender for
152 * @param method_name Original method name from PSYC (may be more
153 * specific than the registered method name due to try-and-slice matching).
154 * FIXME: no try-and-slice for methods defined here.
155 * @param header_length Number of modifiers in header.
156 * @param header Modifiers present in the message. FIXME: use environment instead?
157 * @param data_offset Byte offset of @a data in the overall data of the method.
158 * @param data_size Number of bytes in @a data.
159 * @param data Data stream given to the method (might not be zero-terminated
160 * if data is binary).
161 * @param frag Fragmentation status for the data.
163 typedef int (*GNUNET_PSYC_Method)(void *cls,
164 const struct GNUNET_PeerIdentity *sender,
166 const char *method_name,
167 size_t header_length,
168 GNUNET_PSYC_Modifier *header,
169 uint64_t data_offset,
172 enum GNUNET_PSYC_MessageFlags flags);
176 * Method called from PSYC upon receiving a join request.
178 * @param cls Closure.
179 * @param peer Peer requesting to join.
180 * @param method_name Method name in the join request.
181 * @param header_length Number of modifiers in header.
182 * @param header Modifiers present in the message.
183 * @param data_size Number of bytes in @a data.
184 * @param data Data stream given to the method (might not be zero-terminated
185 * if data is binary).
187 typedef int (*GNUNET_PSYC_JoinCallback)(void *cls,
188 const struct GNUNET_PeerIdentity *peer,
189 const char *method_name,
190 size_t header_length,
191 GNUNET_PSYC_Modifier *header,
194 struct GNUNET_PSYC_JoinHandle *jh);
198 * Method called from PSYC upon receiving a part request.
200 * @param cls Closure.
201 * @param peer Peer requesting to leave.
202 * @param method_name Method name in the part request.
203 * @param header_length Number of modifiers in header.
204 * @param header Modifiers present in the message.
205 * @param data_size Number of bytes in @a data.
206 * @param data Data stream given to the method (might not be zero-terminated
207 * if data is binary).
209 typedef int (*GNUNET_PSYC_PartCallback)(void *cls,
210 const struct GNUNET_PeerIdentity *peer,
211 const char *method_name,
212 size_t header_length,
213 GNUNET_PSYC_Modifier *header,
216 struct GNUNET_PSYC_PartHandle *ph);
220 * Function to call with the decision made for a join request.
222 * Must be called once and only once in response to an invocation of the
223 * #GNUNET_PSYC_JoinCallback.
225 * @param jh Join request handle.
226 * @param is_admitted #GNUNET_YES if joining is approved,
227 * #GNUNET_NO if it is disapproved
228 * @param method_name Method name for the message transmitted with the response.
229 * @param env Environment containing transient variables for the message, or NULL.
230 * @param data_size Size of @a data.
231 * @param data Data of the message.
234 GNUNET_PSYC_join_decision (struct GNUNET_PSYC_JoinHandle *jh,
236 const char *method_name,
237 const struct GNUNET_ENV_Environment *env,
243 * Send a part acknowledgment.
245 * @param ph Part handle.
248 GNUNET_PSYC_part_ack (struct GNUNET_PSYC_PartHandle *ph);
252 * Handle for the master of a PSYC channel.
254 struct GNUNET_PSYC_Master;
258 * Create a PSYC channel master.
260 * Will create a multicast group identified by the given ECC key. Messages
261 * received from group members will be given to the respective handler methods.
262 * If a new member wants to join a group, the "join" method handler will be
263 * invoked; the join handler must then generate a "join" message to approve the
264 * joining of the new member. The channel can also change group membership
265 * without explicit requests. Note that PSYC doesn't itself "understand" join
266 * or part messages, the respective methods must call other PSYC functions to
267 * inform PSYC about the meaning of the respective events.
269 * @param cfg Configuration to use (to connect to PSYC service).
270 * @param priv_key ECC key that will be used to sign messages for this
271 * PSYC session; public key is used to identify the
272 * PSYC channel; FIXME: we'll likely want to use
273 * NOT the p512 curve here, but a cheaper one in the future
274 * Note that end-users will usually not use the private key
275 * directly, but rather look it up in GADS for places
276 * managed by other users, or select a file with the private
277 * key(s) when setting up their own channels
278 * @param join_policy What is the membership policy of the group?
279 * Used to automate group management decisions.
280 * @param method_cb Function to invoke on messages received from members.
281 * @param join_cb Function to invoke when a peer wants to join.
282 * @param part_cb Function to invoke when a peer wants to part.
283 * @param cls Closure for the callbacks.
284 * @return Handle for the channel master, NULL on error.
286 struct GNUNET_PSYC_Master *
287 GNUNET_PSYC_master_create (const struct GNUNET_CONFIGURATION_Handle *cfg,
288 const struct GNUNET_CRYPTO_EccPrivateKey *priv_key,
289 enum GNUNET_MULTICAST_JoinPolicy join_policy,
290 GNUNET_PSYC_Method method_cb,
291 GNUNET_PSYC_JoinCallback join_cb,
292 GNUNET_PSYC_PartCallback part_cb,
297 * Function called to provide data for a transmission via PSYC.
299 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
300 * invalidates the respective transmission handle.
302 * @param cls Closure.
303 * @param message_id Set to the unique message ID that was generated for
305 * @param data_size[in,out] Initially set to the number of bytes available in @a data,
306 * should be set to the number of bytes written to data (IN/OUT).
307 * @param[out] data Where to write the body of the message to give to the method;
308 * function must copy at most @a *data_size bytes to @a data.
309 * @return #GNUNET_SYSERR on error (fatal, aborts transmission)
310 * #GNUNET_NO on success, if more data is to be transmitted later
311 * (should be used if @a *data_size was not big enough to take all the data)
312 * #GNUNET_YES if this completes the transmission (all data supplied)
314 typedef int (*GNUNET_PSYC_MasterReadyNotify)(void *cls,
321 * Handle for a pending PSYC transmission operation.
323 struct GNUNET_PSYC_MasterTransmitHandle;
327 * Send a message to call a method to all members in the PSYC channel.
329 * @param master Handle to the PSYC channel.
330 * @param increment_group_generation #GNUNET_YES if we need to increment
331 * the group generation counter after transmitting this message.
332 * @param method_name Which method should be invoked.
333 * @param env Environment containing state operations and transient variables
334 * for the message, or NULL.
335 * @param notify Function to call to obtain the arguments.
336 * @param notify_cls Closure for @a notify.
337 * @return Transmission handle, NULL on error (i.e. more than one request queued).
339 struct GNUNET_PSYC_MasterTransmitHandle *
340 GNUNET_PSYC_master_transmit (struct GNUNET_PSYC_Master *master,
341 int increment_group_generation,
342 const char *method_name,
343 const struct GNUNET_ENV_Environment *env,
344 GNUNET_PSYC_MasterReadyNotify notify,
349 * Abort transmission request to channel.
351 * @param th Handle of the request that is being aborted.
354 GNUNET_PSYC_master_transmit_cancel (struct GNUNET_PSYC_MasterTransmitHandle *th);
358 * Destroy a PSYC channel master.
360 * @param master PSYC channel master to terminate.
363 GNUNET_PSYC_master_destroy (struct GNUNET_PSYC_Master *master);
367 * Handle for a PSYC channel slave.
369 struct GNUNET_PSYC_Slave;
373 * Join a PSYC channel.
375 * The entity joining is always the local peer. The user must immediately use
376 * the GNUNET_PSYC_slave_to_master() functions to transmit a @e join_msg to the
377 * channel; if the join request succeeds, the channel state (and @e recent
378 * method calls) will be replayed to the joining member. There is no explicit
379 * notification on failure (as the channel may simply take days to approve,
380 * and disapproval is simply being ignored).
382 * @param cfg Configuration to use.
383 * @param pub_key ECC key that identifies the channel we wish to join.
384 * @param origin Peer identity of the origin.
385 * @param method Function to invoke on messages received from the channel,
386 * typically at least contains functions for @e join and @e part.
387 * @param method_cls Closure for @a method.
388 * @param method_name Method name for the join request.
389 * @param env Environment containing transient variables for the request, or NULL.
390 * @param data_size Number of bytes in @a data.
391 * @param data Payload for the join message.
392 * @return Handle for the slave, NULL on error.
394 struct GNUNET_PSYC_Slave *
395 GNUNET_PSYC_slave_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
396 const struct GNUNET_CRYPTO_EccPublicKey *pub_key,
397 const struct GNUNET_PeerIdentity *origin,
398 GNUNET_PSYC_Method method,
400 const char *method_name,
401 const struct GNUNET_ENV_Environment *env,
407 * Part a PSYC channel.
409 * Will terminate the connection to the PSYC service. Polite clients should
410 * first explicitly send a @e part request (via GNUNET_PSYC_slave_to_master()).
412 * @param slave Slave handle.
413 * @param method_name Method name for the part request.
414 * @param env Environment containing transient variables for the request, or NULL.
415 * @param data_size Number of bytes in @a data.
416 * @param data Payload for the part message.
419 GNUNET_PSYC_slave_part (struct GNUNET_PSYC_Slave *slave,
420 const char *method_name,
421 const struct GNUNET_ENV_Environment *env,
427 * Function called to provide data for a transmission to the channel
428 * master (aka the @e host of the channel).
430 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
431 * invalidates the respective transmission handle.
433 * @param cls Closure.
434 * @param data_size[in,out] Initially set to the number of bytes available in @a data,
435 * should be set to the number of bytes written to data (IN/OUT).
436 * @param[out] data Where to write the body of the message to give to the method;
437 * function must copy at most @a *data_size bytes to @a data.
438 * @return #GNUNET_SYSERR on error (fatal, aborts transmission).
439 * #GNUNET_NO on success, if more data is to be transmitted later.
440 * #GNUNET_YES if this completes the transmission (all data supplied).
442 typedef int (*GNUNET_PSYC_SlaveReadyNotify)(void *cls,
448 * Handle for a pending PSYC transmission operation.
450 struct GNUNET_PSYC_SlaveTransmitHandle;
454 * Request a message to be sent to the channel master.
456 * @param slave Slave handle.
457 * @param method_name Which (PSYC) method should be invoked (on host).
458 * @param env Environment containing transient variables for the message, or NULL.
459 * @param notify Function to call when we are allowed to transmit (to get data).
460 * @param notify_cls Closure for @a notify.
461 * @return Transmission handle, NULL on error (i.e. more than one request queued).
463 struct GNUNET_PSYC_SlaveTransmitHandle *
464 GNUNET_PSYC_slave_transmit (struct GNUNET_PSYC_Slave *slave,
465 const char *method_name,
466 const struct GNUNET_ENV_Environment *env,
467 GNUNET_PSYC_SlaveReadyNotify notify,
472 * Abort transmission request to master.
474 * @param th Handle of the request that is being aborted.
477 GNUNET_PSYC_slave_transmit_cancel (struct GNUNET_PSYC_SlaveTransmitHandle *th);
481 * Handle to access PSYC channel operations for both the master and slaves.
483 struct GNUNET_PSYC_Channel;
487 * Convert a channel @a master to a @e channel handle to access the @e channel APIs.
489 * @param master Channel master handle.
490 * @return Channel handle, valid for as long as @a master is valid.
492 struct GNUNET_PSYC_Channel *
493 GNUNET_PSYC_master_get_channel (struct GNUNET_PSYC_Master *master);
497 * Convert @a slave to a @e channel handle to access the @e channel APIs.
499 * @param slave Slave handle.
500 * @return Channel handle, valid for as long as @a slave is valid.
502 struct GNUNET_PSYC_Channel *
503 GNUNET_PSYC_slave_get_channel (struct GNUNET_PSYC_Slave *slave);
507 * Add a member to the channel.
509 * Note that this will NOT generate any PSYC traffic, it will merely update the
510 * local data base to modify how we react to <em>membership test</em> queries.
511 * The channel master still needs to explicitly transmit a @e join message to
512 * notify other channel members and they then also must still call this function
513 * in their respective methods handling the @e join message. This way, how @e
514 * join and @e part operations are exactly implemented is still up to the
515 * application; for example, there might be a @e part_all method to kick out
518 * Note that channel members are explicitly trusted to execute such methods
519 * correctly; not doing so correctly will result in either denying members
520 * access or offering access to channel data to non-members.
522 * @param channel Channel handle.
523 * @param member Which peer to add.
524 * @param message_id Message ID for the message that changed the membership.
527 GNUNET_PSYC_channel_member_add (struct GNUNET_PSYC_Channel *channel,
528 const struct GNUNET_PeerIdentity *member,
529 uint64_t message_id);
533 * Remove a member from the channel.
535 * Note that this will NOT generate any PSYC traffic, it will merely update the
536 * local data base to modify how we react to <em>membership test</em> queries.
537 * The channel master still needs to explicitly transmit a @e part message to
538 * notify other channel members and they then also must still call this function
539 * in their respective methods handling the @e part message. This way, how
540 * @e join and @e part operations are exactly implemented is still up to the
541 * application; for example, there might be a @e part_all message to kick out
544 * Note that channel members are explicitly trusted to perform these
545 * operations correctly; not doing so correctly will result in either
546 * denying members access or offering access to channel data to
549 * @param channel Channel handle.
550 * @param member Which peer to remove.
551 * @param message_id Message ID for the message that changed the membership.
554 GNUNET_PSYC_channel_member_remove (struct GNUNET_PSYC_Channel *channel,
555 const struct GNUNET_PeerIdentity *member,
556 uint64_t message_id);
560 * Function called to inform a member about stored state values for a channel.
562 * @param cls Closure.
563 * @param name Name of the state variable.
564 * @param value Value of the state variable.
565 * @param value_size Number of bytes in @a value.
567 typedef void (*GNUNET_PSYC_StateCallback)(void *cls,
574 * Handle to a story telling operation.
576 struct GNUNET_PSYC_Story;
580 * Request to be told the message history of the channel.
582 * Historic messages (but NOT the state at the time) will be replayed (given to
583 * the normal method handlers) if available and if access is permitted.
585 * To get the latest message, use 0 for both the start and end message ID.
587 * @param channel Which channel should be replayed?
588 * @param start_message_id Earliest interesting point in history.
589 * @param end_message_id Last (exclusive) interesting point in history.
590 * @param method Function to invoke on messages received from the story.
591 * @param method_cls Closure for @a method.
592 * @param finish_cb Function to call when the requested story has been fully
593 * told (counting message IDs might not suffice, as some messages
594 * might be secret and thus the listener would not know the story is
595 * finished without being told explicitly); once this function
596 * has been called, the client must not call
597 * GNUNET_PSYC_channel_story_tell_cancel() anymore.
598 * @param finish_cb_cls Closure to finish_cb.
599 * @return Handle to cancel story telling operation.
601 struct GNUNET_PSYC_Story *
602 GNUNET_PSYC_channel_story_tell (struct GNUNET_PSYC_Channel *channel,
603 uint64_t start_message_id,
604 uint64_t end_message_id,
605 GNUNET_PSYC_Method method,
607 void (*finish_cb)(void *),
608 void *finish_cb_cls);
612 * Abort story telling.
614 * This function must not be called from within method handlers (as given to
615 * GNUNET_PSYC_slave_join()) of the slave.
617 * @param story Story telling operation to stop.
620 GNUNET_PSYC_channel_story_tell_cancel (struct GNUNET_PSYC_Story *story);
624 * Call the given callback on all matching values (including variables) in the
627 * The callback is invoked synchronously on all matching states (as the state is
628 * fully replicated in the library in this process; channel states should be
629 * small, large data is to be passed as streaming data to methods).
631 * A name matches if it includes the @a state_name prefix, thus requesting the
632 * empty state ("") will match all values; requesting "_a_b" will also return
633 * values stored under "_a_b_c".
635 * @param channel Channel handle.
636 * @param state_name Name of the state to query (full name
637 * might be longer, this is only the prefix that must match).
638 * @param cb Function to call on the matching state values.
639 * @param cb_cls Closure for @a cb.
640 * @return Message ID for which the state was returned (last seen
644 GNUNET_PSYC_channel_state_get_all (struct GNUNET_PSYC_Channel *channel,
645 const char *state_name,
646 GNUNET_PSYC_StateCallback cb,
651 * Obtain the current value of the best-matching value in the state
652 * (including variables).
654 * Note that variables are only valid during a #GNUNET_PSYC_Method invocation, as
655 * variables are only valid for the duration of a method invocation.
657 * If the requested variable name does not have an exact state in
658 * the state, the nearest less-specific name is matched; for example,
659 * requesting "_a_b" will match "_a" if "_a_b" does not exist.
661 * @param channel Channel handle.
662 * @param variable_name Name of the variable to query.
663 * @param[out] return_value_size Set to number of bytes in variable,
664 * needed as variables might contain binary data and
665 * might also not be 0-terminated; set to 0 on errors.
666 * @return NULL on error (no matching state or variable), pointer
667 to the respective value otherwise.
670 GNUNET_PSYC_channel_state_get (struct GNUNET_PSYC_Channel *channel,
671 const char *variable_name,
672 size_t *return_value_size);
675 #if 0 /* keep Emacsens' auto-indent happy */
682 /* ifndef GNUNET_PSYC_SERVICE_H */
684 /* end of gnunet_psyc_service.h */