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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_env_lib.h"
90 #include "gnunet_multicast_service.h"
94 * Version number of GNUnet-PSYC API.
96 #define GNUNET_PSYC_VERSION 0x00000000
100 * Policy flags for a channel.
102 enum GNUNET_PSYC_ChannelFlags
105 * Admission must be confirmed by the master.
107 GNUNET_PSYC_CHANNEL_ADMISSION_CONTROL = 1 << 0,
110 * Past messages are only available to slaves who were admitted at the time
111 * they were sent to the channel.
113 GNUNET_PSYC_CHANNEL_RESTRICTED_HISTORY = 1 << 1,
117 * PSYC channel policies.
119 enum GNUNET_PSYC_Policy
122 * Anyone can join the channel, without announcing his presence;
123 * all messages are always public and can be distributed freely.
124 * Joins may be announced, but this is not required.
126 GNUNET_PSYC_CHANNEL_ANONYMOUS = 0,
129 * The master must approve membership to the channel, messages must only be
130 * distributed to current channel slaves. This includes the channel
131 * state as well as transient messages.
133 GNUNET_PSYC_CHANNEL_PRIVATE
134 = GNUNET_PSYC_CHANNEL_ADMISSION_CONTROL
135 | GNUNET_PSYC_CHANNEL_RESTRICTED_HISTORY,
139 * Anyone can freely join the channel (no approval required);
140 * however, messages must only be distributed to current channel
141 * slaves, so the master must still acknowledge that the slave
142 * joined before transient messages are delivered. As approval is
143 * guaranteed, the presistent channel state can be synchronized freely
144 * immediately, prior to master confirmation.
146 GNUNET_PSYC_CHANNEL_OPEN
147 = GNUNET_PSYC_CHANNEL_RESTRICTED_HISTORY,
150 * The master must approve joins to the channel, but past messages can be
151 * freely distributed to slaves.
153 GNUNET_PSYC_CHANNEL_CLOSED
154 = GNUNET_PSYC_CHANNEL_ADMISSION_CONTROL,
161 enum GNUNET_PSYC_MessageFlags
164 * First fragment of a message.
166 GNUNET_PSYC_MESSAGE_FIRST_FRAGMENT = 1 << 0,
169 * Last fragment of a message.
171 GNUNET_PSYC_MESSAGE_LAST_FRAGMENT = 1 << 1,
174 * OR'ed flags if message is not fragmented.
176 GNUNET_PSYC_MESSAGE_NOT_FRAGMENTED
177 = GNUNET_PSYC_MESSAGE_FIRST_FRAGMENT
178 | GNUNET_PSYC_MESSAGE_LAST_FRAGMENT,
181 * Historic message, retrieved from PSYCstore.
183 GNUNET_PSYC_MESSAGE_HISTORIC = 1 << 30
188 * Handle that identifies a join request.
190 * Used to match calls to #GNUNET_PSYC_JoinCallback to the
191 * corresponding calls to GNUNET_PSYC_join_decision().
193 struct GNUNET_PSYC_JoinHandle;
197 * Method called from PSYC upon receiving a message indicating a call
200 * @param cls Closure.
201 * @param slave_key Who transmitted the message.
202 * - NULL for multicast messages from the master.
203 * - The hash of the sending slave's public key for unicast requests from
204 * one of the slaves to the master.
205 * @param message_id Unique message counter for this message.
206 * Unique only in combination with the given sender for this channel.
207 * @param method_name Method name from PSYC.
208 * @param modifier_count Number of elements in the @a modifiers array.
209 * @param modifiers State modifiers and transient variables for the message.
210 * @param data_offset Byte offset of @a data in the overall data of the method.
211 * @param data Data stream given to the method (might not be zero-terminated
212 * if data is binary).
213 * @param data_size Number of bytes in @a data.
214 * @param frag Fragmentation status for the data.
217 (*GNUNET_PSYC_Method) (void *cls,
218 const struct GNUNET_CRYPTO_EccPublicSignKey *slave_key,
220 const char *method_name,
221 size_t modifier_count,
222 const struct GNUNET_ENV_Modifier *modifiers,
223 uint64_t data_offset,
226 enum GNUNET_PSYC_MessageFlags flags);
230 * Method called from PSYC upon receiving a join request.
232 * @param cls Closure.
233 * @param slave requesting to join.
234 * @param method_name Method name in the join request.
235 * @param variable_count Number of elements in the @a variables array.
236 * @param variables Transient variables for the join request.
237 * @param data Data stream given to the method (might not be zero-terminated
238 * if data is binary).
239 * @param data_size Number of bytes in @a data.
240 * @param jh Join handle to use with GNUNET_PSYC_join_decision()
243 (*GNUNET_PSYC_JoinCallback) (void *cls,
244 const struct GNUNET_CRYPTO_EccPublicSignKey *slave_key,
245 const char *method_name,
246 size_t variable_count,
247 const struct GNUNET_ENV_Modifier *variables,
250 struct GNUNET_PSYC_JoinHandle *jh);
254 * Function to call with the decision made for a join request.
256 * Must be called once and only once in response to an invocation of the
257 * #GNUNET_PSYC_JoinCallback.
259 * @param jh Join request handle.
260 * @param is_admitted #GNUNET_YES if joining is approved,
261 * #GNUNET_NO if it is disapproved.
262 * @param relay_count Number of relays given.
263 * @param relays Array of suggested peers that might be useful relays to use
264 * when joining the multicast group (essentially a list of peers that
265 * are already part of the multicast group and might thus be willing
266 * to help with routing). If empty, only this local peer (which must
267 * be the multicast origin) is a good candidate for building the
268 * multicast tree. Note that it is unnecessary to specify our own
269 * peer identity in this array.
270 * @param method_name Method name for the message transmitted with the response.
271 * @param env Environment containing transient variables for the message, or NULL.
272 * @param data Data of the message.
273 * @param data_size Size of @a data.
276 GNUNET_PSYC_join_decision (struct GNUNET_PSYC_JoinHandle *jh,
278 unsigned int relay_count,
279 const struct GNUNET_PeerIdentity *relays,
280 const char *method_name,
281 const struct GNUNET_ENV_Environment *env,
287 * Handle for the master of a PSYC channel.
289 struct GNUNET_PSYC_Master;
293 * Start a PSYC master channel.
295 * Will start a multicast group identified by the given ECC key. Messages
296 * received from group members will be given to the respective handler methods.
297 * If a new member wants to join a group, the "join" method handler will be
298 * invoked; the join handler must then generate a "join" message to approve the
299 * joining of the new member. The channel can also change group membership
300 * without explicit requests. Note that PSYC doesn't itself "understand" join
301 * or part messages, the respective methods must call other PSYC functions to
302 * inform PSYC about the meaning of the respective events.
304 * @param cfg Configuration to use (to connect to PSYC service).
305 * @param channel_key ECC key that will be used to sign messages for this
306 * PSYC session. The public key is used to identify the PSYC channel.
307 * Note that end-users will usually not use the private key directly, but
308 * rather look it up in GADS for places managed by other users, or select
309 * a file with the private key(s) when setting up their own channels
310 * FIXME: we'll likely want to use NOT the p521 curve here, but a cheaper
312 * @param policy Channel policy specifying join and history restrictions.
313 * Used to automate join decisions.
314 * @param method Function to invoke on messages received from slaves.
315 * @param join_cb Function to invoke when a peer wants to join.
316 * @param cls Closure for @a method and @a join_cb.
317 * @return Handle for the channel master, NULL on error.
319 struct GNUNET_PSYC_Master *
320 GNUNET_PSYC_master_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
321 const struct GNUNET_CRYPTO_EccPrivateKey *channel_key,
322 enum GNUNET_PSYC_Policy policy,
323 GNUNET_PSYC_Method method,
324 GNUNET_PSYC_JoinCallback join_cb,
329 * Function called to provide data for a transmission via PSYC.
331 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
332 * invalidates the respective transmission handle.
334 * @param cls Closure.
335 * @param message_id Set to the unique message ID that was generated for
337 * @param[in,out] data_size Initially set to the number of bytes available in
338 * @a data, should be set to the number of bytes written to data.
339 * @param[out] data Where to write the body of the message to give to the
340 * method. The function must copy at most @a data_size bytes to @a data.
341 * @return #GNUNET_SYSERR on error (fatal, aborts transmission)
342 * #GNUNET_NO on success, if more data is to be transmitted later
343 * (should be used if @a data_size was not big enough to take all the data)
344 * #GNUNET_YES if this completes the transmission (all data supplied)
347 (*GNUNET_PSYC_MasterTransmitNotify) (void *cls,
354 * Flags for transmitting messages to a channel by the master.
356 enum GNUNET_PSYC_MasterTransmitFlags
359 * Whether this message should reset the channel state,
360 * i.e. remove all previously stored state variables.
362 GNUNET_PSYC_MASTER_TRANSMIT_RESET_STATE = 1 << 0,
365 * Whether we need to increment the group generation counter after
366 * transmitting this message.
368 GNUNET_PSYC_MASTER_TRANSMIT_INC_GROUP_GEN = 1 << 1,
371 * Add PSYC header variable with the hash of the current channel state.
373 GNUNET_PSYC_MASTER_TRANSMIT_ADD_STATE_HASH = 1 << 2
378 * Handle for a pending PSYC transmission operation.
380 struct GNUNET_PSYC_MasterTransmitHandle;
384 * Send a message to call a method to all members in the PSYC channel.
386 * @param master Handle to the PSYC channel.
387 * @param method_name Which method should be invoked.
388 * @param env Environment containing state operations and transient variables
389 * for the message, or NULL.
390 * @param notify Function to call to obtain the arguments.
391 * @param notify_cls Closure for @a notify.
392 * @param flags Flags for the message being transmitted.
393 * @return Transmission handle, NULL on error (i.e. more than one request queued).
395 struct GNUNET_PSYC_MasterTransmitHandle *
396 GNUNET_PSYC_master_transmit (struct GNUNET_PSYC_Master *master,
397 const char *method_name,
398 const struct GNUNET_ENV_Environment *env,
399 GNUNET_PSYC_MasterTransmitNotify notify,
401 enum GNUNET_PSYC_MasterTransmitFlags flags);
405 * Abort transmission request to channel.
407 * @param th Handle of the request that is being aborted.
410 GNUNET_PSYC_master_transmit_cancel (struct GNUNET_PSYC_MasterTransmitHandle *th);
414 * Stop a PSYC master channel.
416 * @param master PSYC channel master to stop.
419 GNUNET_PSYC_master_stop (struct GNUNET_PSYC_Master *master);
423 * Handle for a PSYC channel slave.
425 struct GNUNET_PSYC_Slave;
429 * Join a PSYC channel.
431 * The entity joining is always the local peer. The user must immediately use
432 * the GNUNET_PSYC_slave_to_master() functions to transmit a @e join_msg to the
433 * channel; if the join request succeeds, the channel state (and @e recent
434 * method calls) will be replayed to the joining member. There is no explicit
435 * notification on failure (as the channel may simply take days to approve,
436 * and disapproval is simply being ignored).
438 * @param cfg Configuration to use.
439 * @param channel_key ECC public key that identifies the channel we wish to join.
440 * @param slave_key ECC private-public key pair that identifies the slave, and
441 * used by multicast to sign the join request and subsequent unicast
442 * requests sent to the master.
443 * @param origin Peer identity of the origin.
444 * @param relay_count Number of peers in the @a relays array.
445 * @param relays Peer identities of members of the multicast group, which serve
446 * as relays and used to join the group at.
447 * @param method Function to invoke on messages received from the channel,
448 * typically at least contains functions for @e join and @e part.
449 * @param join_cb Function to invoke when a peer wants to join.
450 * @param cls Closure for @a method_cb and @a join_cb.
451 * @param method_name Method name for the join request.
452 * @param env Environment containing transient variables for the request, or NULL.
453 * @param data Payload for the join message.
454 * @param data_size Number of bytes in @a data.
455 * @return Handle for the slave, NULL on error.
457 struct GNUNET_PSYC_Slave *
458 GNUNET_PSYC_slave_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
459 const struct GNUNET_CRYPTO_EccPublicSignKey *channel_key,
460 const struct GNUNET_CRYPTO_EccPrivateKey *slave_key,
461 const struct GNUNET_PeerIdentity *origin,
463 const struct GNUNET_PeerIdentity *relays,
464 GNUNET_PSYC_Method method,
465 GNUNET_PSYC_JoinCallback join_cb,
467 const char *method_name,
468 const struct GNUNET_ENV_Environment *env,
474 * Part a PSYC channel.
476 * Will terminate the connection to the PSYC service. Polite clients should
477 * first explicitly send a @e part request (via GNUNET_PSYC_slave_to_master()).
479 * @param slave Slave handle.
482 GNUNET_PSYC_slave_part (struct GNUNET_PSYC_Slave *slave);
486 * Function called to provide data for a transmission to the channel
487 * master (aka the @e host of the channel).
489 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
490 * invalidates the respective transmission handle.
492 * @param cls Closure.
493 * @param[in,out] data_size Initially set to the number of bytes available in @a data,
494 * should be set to the number of bytes written to data (IN/OUT).
495 * @param[out] data Where to write the body of the message to give to the method;
496 * function must copy at most @a *data_size bytes to @a data.
497 * @return #GNUNET_SYSERR on error (fatal, aborts transmission).
498 * #GNUNET_NO on success, if more data is to be transmitted later.
499 * #GNUNET_YES if this completes the transmission (all data supplied).
502 (*GNUNET_PSYC_SlaveTransmitNotify) (void *cls,
508 * Flags for transmitting messages to the channel master by a slave.
510 enum GNUNET_PSYC_SlaveTransmitFlags;
513 * Handle for a pending PSYC transmission operation.
515 struct GNUNET_PSYC_SlaveTransmitHandle;
519 * Request a message to be sent to the channel master.
521 * @param slave Slave handle.
522 * @param method_name Which (PSYC) method should be invoked (on host).
523 * @param env Environment containing transient variables for the message, or NULL.
524 * @param notify Function to call when we are allowed to transmit (to get data).
525 * @param notify_cls Closure for @a notify.
526 * @param flags Flags for the message being transmitted.
527 * @return Transmission handle, NULL on error (i.e. more than one request queued).
529 struct GNUNET_PSYC_SlaveTransmitHandle *
530 GNUNET_PSYC_slave_transmit (struct GNUNET_PSYC_Slave *slave,
531 const char *method_name,
532 const struct GNUNET_ENV_Environment *env,
533 GNUNET_PSYC_SlaveTransmitNotify notify,
535 enum GNUNET_PSYC_SlaveTransmitFlags flags);
539 * Abort transmission request to master.
541 * @param th Handle of the request that is being aborted.
544 GNUNET_PSYC_slave_transmit_cancel (struct GNUNET_PSYC_SlaveTransmitHandle *th);
548 * Handle to access PSYC channel operations for both the master and slaves.
550 struct GNUNET_PSYC_Channel;
554 * Convert a channel @a master to a @e channel handle to access the @e channel APIs.
556 * @param master Channel master handle.
557 * @return Channel handle, valid for as long as @a master is valid.
559 struct GNUNET_PSYC_Channel *
560 GNUNET_PSYC_master_get_channel (struct GNUNET_PSYC_Master *master);
564 * Convert @a slave to a @e channel handle to access the @e channel APIs.
566 * @param slave Slave handle.
567 * @return Channel handle, valid for as long as @a slave is valid.
569 struct GNUNET_PSYC_Channel *
570 GNUNET_PSYC_slave_get_channel (struct GNUNET_PSYC_Slave *slave);
574 * Add a slave to the channel's membership list.
576 * Note that this will NOT generate any PSYC traffic, it will merely update the
577 * local database to modify how we react to <em>membership test</em> queries.
578 * The channel master still needs to explicitly transmit a @e join message to
579 * notify other channel members and they then also must still call this function
580 * in their respective methods handling the @e join message. This way, how @e
581 * join and @e part operations are exactly implemented is still up to the
582 * application; for example, there might be a @e part_all method to kick out
585 * Note that channel slaves are explicitly trusted to execute such methods
586 * correctly; not doing so correctly will result in either denying other slaves
587 * access or offering access to channel data to non-members.
589 * @param channel Channel handle.
590 * @param slave_key Identity of channel slave to add.
591 * @param announced_at ID of the message that announced the membership change.
592 * @param effective_since Addition of slave is in effect since this message ID.
595 GNUNET_PSYC_channel_slave_add (struct GNUNET_PSYC_Channel *channel,
596 const struct GNUNET_CRYPTO_EccPublicSignKey *slave_key,
597 uint64_t announced_at,
598 uint64_t effective_since);
602 * Remove a slave from the channel's membership list.
604 * Note that this will NOT generate any PSYC traffic, it will merely update the
605 * local database to modify how we react to <em>membership test</em> queries.
606 * The channel master still needs to explicitly transmit a @e part message to
607 * notify other channel members and they then also must still call this function
608 * in their respective methods handling the @e part message. This way, how
609 * @e join and @e part operations are exactly implemented is still up to the
610 * application; for example, there might be a @e part_all message to kick out
613 * Note that channel members are explicitly trusted to perform these
614 * operations correctly; not doing so correctly will result in either
615 * denying members access or offering access to channel data to
618 * @param channel Channel handle.
619 * @param slave_key Identity of channel slave to remove.
620 * @param announced_at ID of the message that announced the membership change.
623 GNUNET_PSYC_channel_slave_remove (struct GNUNET_PSYC_Channel *channel,
624 const struct GNUNET_CRYPTO_EccPublicSignKey *slave_key,
625 uint64_t announced_at);
629 * Function called to inform a member about stored state values for a channel.
631 * @param cls Closure.
632 * @param name Name of the state variable. A NULL value indicates that there
633 * are no more state variables to be returned.
634 * @param value Value of the state variable.
635 * @param value_size Number of bytes in @a value.
638 (*GNUNET_PSYC_StateCallback) (void *cls,
645 * Function called when a requested operation has finished.
647 * @param cls Closure.
650 (*GNUNET_PSYC_FinishCallback) (void *cls);
654 * Handle to a story telling operation.
656 struct GNUNET_PSYC_Story;
660 * Request to be told the message history of the channel.
662 * Historic messages (but NOT the state at the time) will be replayed (given to
663 * the normal method handlers) if available and if access is permitted.
665 * To get the latest message, use 0 for both the start and end message ID.
667 * @param channel Which channel should be replayed?
668 * @param start_message_id Earliest interesting point in history.
669 * @param end_message_id Last (exclusive) interesting point in history.
670 * @param method Function to invoke on messages received from the story.
671 * @param finish_cb Function to call when the requested story has been fully
672 * told (counting message IDs might not suffice, as some messages
673 * might be secret and thus the listener would not know the story is
674 * finished without being told explicitly); once this function
675 * has been called, the client must not call
676 * GNUNET_PSYC_channel_story_tell_cancel() anymore.
677 * @param cls Closure for the callbacks.
678 * @return Handle to cancel story telling operation.
680 struct GNUNET_PSYC_Story *
681 GNUNET_PSYC_channel_story_tell (struct GNUNET_PSYC_Channel *channel,
682 uint64_t start_message_id,
683 uint64_t end_message_id,
684 GNUNET_PSYC_Method method,
685 GNUNET_PSYC_FinishCallback *finish_cb,
690 * Abort story telling.
692 * This function must not be called from within method handlers (as given to
693 * GNUNET_PSYC_slave_join()) of the slave.
695 * @param story Story telling operation to stop.
698 GNUNET_PSYC_channel_story_tell_cancel (struct GNUNET_PSYC_Story *story);
700 struct GNUNET_PSYC_StateQuery;
704 * Retrieve the best matching channel state variable.
706 * If the requested variable name is not present in the state, the nearest
707 * less-specific name is matched; for example, requesting "_a_b" will match "_a"
708 * if "_a_b" does not exist.
710 * @param channel Channel handle.
711 * @param full_name Full name of the requested variable, the actual variable
712 * returned might have a shorter name..
713 * @param cb Function called once when a matching state variable is found.
714 * Not called if there's no matching state variable.
715 * @param cb_cls Closure for the callbacks.
716 * @return Handle that can be used to cancel the query operation.
718 struct GNUNET_PSYC_StateQuery *
719 GNUNET_PSYC_channel_state_get (struct GNUNET_PSYC_Channel *channel,
720 const char *full_name,
721 GNUNET_PSYC_StateCallback cb,
726 * Return all channel state variables whose name matches a given prefix.
728 * A name matches if it starts with the given @a name_prefix, thus requesting the
729 * empty prefix ("") will match all values; requesting "_a_b" will also return
730 * values stored under "_a_b_c".
732 * The @a state_cb is invoked on all matching state variables asynchronously, as
733 * the state is stored in and retrieved from the PSYCstore,
735 * @param channel Channel handle.
736 * @param name_prefix Prefix of the state variable name to match.
737 * @param cb Function to call with the matching state variables.
738 * @param cb_cls Closure for the callbacks.
739 * @return Handle that can be used to cancel the query operation.
741 struct GNUNET_PSYC_StateQuery *
742 GNUNET_PSYC_channel_state_get_prefix (struct GNUNET_PSYC_Channel *channel,
743 const char *name_prefix,
744 GNUNET_PSYC_StateCallback cb,
749 * Cancel a state query operation.
751 * @param query Handle for the operation to cancel.
754 GNUNET_PSYC_channel_state_get_cancel (struct GNUNET_PSYC_StateQuery *query);
757 #if 0 /* keep Emacsens' auto-indent happy */
764 /* ifndef GNUNET_PSYC_SERVICE_H */
766 /* end of gnunet_psyc_service.h */