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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 GNS
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 (GNS)
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
118 * PSYC channel policies.
120 enum GNUNET_PSYC_Policy
123 * Anyone can join the channel, without announcing his presence;
124 * all messages are always public and can be distributed freely.
125 * Joins may be announced, but this is not required.
127 GNUNET_PSYC_CHANNEL_ANONYMOUS = 0,
130 * The master must approve membership to the channel, messages must only be
131 * distributed to current channel slaves. This includes the channel
132 * state as well as transient messages.
134 GNUNET_PSYC_CHANNEL_PRIVATE
135 = GNUNET_PSYC_CHANNEL_ADMISSION_CONTROL
136 | GNUNET_PSYC_CHANNEL_RESTRICTED_HISTORY
140 * Anyone can freely join the channel (no approval required);
141 * however, messages must only be distributed to current channel
142 * slaves, so the master must still acknowledge that the slave
143 * joined before transient messages are delivered. As approval is
144 * guaranteed, the presistent channel state can be synchronized freely
145 * immediately, prior to master confirmation.
147 GNUNET_PSYC_CHANNEL_OPEN
148 = GNUNET_PSYC_CHANNEL_RESTRICTED_HISTORY,
151 * The master must approve joins to the channel, but past messages can be
152 * freely distributed to slaves.
154 GNUNET_PSYC_CHANNEL_CLOSED
155 = GNUNET_PSYC_CHANNEL_ADMISSION_CONTROL,
160 enum GNUNET_PSYC_MessageFlags
163 * Historic message, retrieved from PSYCstore.
165 GNUNET_PSYC_MESSAGE_HISTORIC = 1 << 0,
168 * Request from slave to master.
170 GNUNET_PSYC_MESSAGE_REQUEST = 1 << 1,
173 * Message can be delivered out of order.
175 GNUNET_PSYC_MESSAGE_ORDER_ANY = 1 << 2
180 * Values for the @a state_delta field of GNUNET_PSYC_MessageHeader.
182 enum GNUNET_PSYC_StateDeltaValues
184 GNUNET_PSYC_STATE_RESET = 0,
186 GNUNET_PSYC_STATE_NOT_MODIFIED = UINT64_MAX
190 GNUNET_NETWORK_STRUCT_BEGIN
193 * Header of a PSYC message.
195 * Only present when receiving a message.
197 struct GNUNET_PSYC_MessageHeader
200 * Generic message header with size and type information.
202 struct GNUNET_MessageHeader header;
205 * Flags for this message fragment.
207 * @see enum GNUNET_PSYC_MessageFlags
209 uint32_t flags GNUNET_PACKED;
212 * Number of the message this message part belongs to.
213 * Monotonically increasing from 1.
215 uint64_t message_id GNUNET_PACKED;
218 * Sending slave's public key.
219 * Not set if the message is from the master.
221 struct GNUNET_CRYPTO_EddsaPublicKey slave_key;
223 /* Followed by concatenated PSYC message parts:
224 * messages with GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_* types
230 * The method of a message.
232 struct GNUNET_PSYC_MessageMethod
235 * Type: GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_METHOD
237 struct GNUNET_MessageHeader header;
240 * OR'ed GNUNET_PSYC_MasterTransmitFlags
242 uint32_t flags GNUNET_PACKED;
245 * Number of message IDs since the last message that contained state
246 * operations. @see enum GNUNET_PSYC_StateDeltaValues
248 uint64_t state_delta GNUNET_PACKED;
250 /* Followed by NUL-terminated method name. */
255 * A modifier of a message.
257 struct GNUNET_PSYC_MessageModifier
260 * Type: GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MODIFIER
262 struct GNUNET_MessageHeader header;
267 uint32_t value_size GNUNET_PACKED;
270 * Size of name, including NUL terminator.
272 uint16_t name_size GNUNET_PACKED;
275 * enum GNUNET_ENV_Operator
279 /* Followed by NUL-terminated name, then the value. */
282 GNUNET_NETWORK_STRUCT_END
285 #define GNUNET_PSYC_MODIFIER_MAX_PAYLOAD \
286 GNUNET_MULTICAST_FRAGMENT_MAX_PAYLOAD \
287 - sizeof (struct GNUNET_PSYC_MessageModifier)
289 #define GNUNET_PSYC_MOD_CONT_MAX_PAYLOAD \
290 GNUNET_MULTICAST_FRAGMENT_MAX_PAYLOAD \
291 - sizeof (struct GNUNET_MessageHeader)
293 #define GNUNET_PSYC_DATA_MAX_PAYLOAD \
294 GNUNET_MULTICAST_FRAGMENT_MAX_PAYLOAD \
295 - sizeof (struct GNUNET_MessageHeader)
299 * Handle that identifies a join request.
301 * Used to match calls to #GNUNET_PSYC_JoinCallback to the
302 * corresponding calls to GNUNET_PSYC_join_decision().
304 struct GNUNET_PSYC_JoinHandle;
308 * Method called from PSYC upon receiving part of a message.
310 * @param cls Closure.
311 * @param msg Message part, one of the following types:
312 * - GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_HEADER
313 * - GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_METHOD
314 * - GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MODIFIER
315 * - GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MOD_CONT
316 * - GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_DATA
319 (*GNUNET_PSYC_MessageCallback) (void *cls,
322 const struct GNUNET_MessageHeader *msg);
326 * Method called from PSYC upon receiving a join request.
328 * @param cls Closure.
329 * @param slave_key Public key of the slave requesting join.
330 * @param join_msg Join message sent along with the request.
331 * @param jh Join handle to use with GNUNET_PSYC_join_decision()
334 (*GNUNET_PSYC_JoinRequestCallback) (void *cls,
336 GNUNET_CRYPTO_EddsaPublicKey *slave_key,
338 GNUNET_PSYC_MessageHeader *join_msg,
339 struct GNUNET_PSYC_JoinHandle *jh);
343 * Function to call with the decision made for a join request.
345 * Must be called once and only once in response to an invocation of the
346 * #GNUNET_PSYC_JoinCallback.
348 * @param jh Join request handle.
349 * @param is_admitted #GNUNET_YES if the join is approved,
350 * #GNUNET_NO if it is disapproved,
351 * #GNUNET_SYSERR if we cannot answer the request.
352 * @param relay_count Number of relays given.
353 * @param relays Array of suggested peers that might be useful relays to use
354 * when joining the multicast group (essentially a list of peers that
355 * are already part of the multicast group and might thus be willing
356 * to help with routing). If empty, only this local peer (which must
357 * be the multicast origin) is a good candidate for building the
358 * multicast tree. Note that it is unnecessary to specify our own
359 * peer identity in this array.
360 * @param join_resp Application-dependent join response message to send along
363 * @return #GNUNET_OK on success,
364 * #GNUNET_SYSERR if @a join_resp is too large.
367 GNUNET_PSYC_join_decision (struct GNUNET_PSYC_JoinHandle *jh,
369 uint32_t relay_count,
370 const struct GNUNET_PeerIdentity *relays,
371 const struct GNUNET_PSYC_MessageHeader *join_resp);
375 * Handle for the master of a PSYC channel.
377 struct GNUNET_PSYC_Master;
381 * Function called after the channel master started.
383 * @param cls Closure.
384 * @param max_message_id Last message ID sent to the channel.
387 (*GNUNET_PSYC_MasterStartCallback) (void *cls, uint64_t max_message_id);
391 * Start a PSYC master channel.
393 * Will start a multicast group identified by the given ECC key. Messages
394 * received from group members will be given to the respective handler methods.
395 * If a new member wants to join a group, the "join" method handler will be
396 * invoked; the join handler must then generate a "join" message to approve the
397 * joining of the new member. The channel can also change group membership
398 * without explicit requests. Note that PSYC doesn't itself "understand" join
399 * or part messages, the respective methods must call other PSYC functions to
400 * inform PSYC about the meaning of the respective events.
402 * @param cfg Configuration to use (to connect to PSYC service).
403 * @param channel_key ECC key that will be used to sign messages for this
404 * PSYC session. The public key is used to identify the PSYC channel.
405 * Note that end-users will usually not use the private key directly, but
406 * rather look it up in GNS for places managed by other users, or select
407 * a file with the private key(s) when setting up their own channels
408 * FIXME: we'll likely want to use NOT the p521 curve here, but a cheaper
410 * @param policy Channel policy specifying join and history restrictions.
411 * Used to automate join decisions.
412 * @param master_start_cb Function to invoke after the channel master started.
413 * @param join_request_cb Function to invoke when a slave wants to join.
414 * @param message_cb Function to invoke on message parts sent to the channel
415 * and received from slaves
416 * @param cls Closure for @a method and @a join_cb.
418 * @return Handle for the channel master, NULL on error.
420 struct GNUNET_PSYC_Master *
421 GNUNET_PSYC_master_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
422 const struct GNUNET_CRYPTO_EddsaPrivateKey *channel_key,
423 enum GNUNET_PSYC_Policy policy,
424 GNUNET_PSYC_MasterStartCallback master_start_cb,
425 GNUNET_PSYC_JoinRequestCallback join_request_cb,
426 GNUNET_PSYC_MessageCallback message_cb,
431 * Function called to provide data for a transmission via PSYC.
433 * Note that returning #GNUNET_YES or #GNUNET_SYSERR (but not #GNUNET_NO)
434 * invalidates the respective transmission handle.
436 * @param cls Closure.
437 * @param[in,out] data_size Initially set to the number of bytes available in
438 * @a data, should be set to the number of bytes written to data.
439 * @param[out] data Where to write the body of the message to give to the
440 * method. The function must copy at most @a data_size bytes to @a data.
441 * @return #GNUNET_SYSERR on error (fatal, aborts transmission)
442 * #GNUNET_NO on success, if more data is to be transmitted later.
443 * Should be used if @a data_size was not big enough to take all the
444 * data. If 0 is returned in @a data_size the transmission is paused,
445 * and can be resumed with GNUNET_PSYC_master_transmit_resume().
446 * #GNUNET_YES if this completes the transmission (all data supplied)
449 (*GNUNET_PSYC_TransmitNotifyData) (void *cls,
454 * Function called to provide a modifier for a transmission via PSYC.
456 * Note that returning #GNUNET_YES or #GNUNET_SYSERR (but not #GNUNET_NO)
457 * invalidates the respective transmission handle.
459 * @param cls Closure.
460 * @param[in,out] data_size Initially set to the number of bytes available in
461 * @a data, should be set to the number of bytes written to data.
462 * @param[out] data Where to write the modifier's name and value.
463 * The function must copy at most @a data_size bytes to @a data.
464 * When this callback is first called for a modifier, @a data should
465 * contain: "name\0value". If the whole value does not fit, subsequent
466 * calls to this function should write continuations of the value to
468 * @param[out] oper Where to write the operator of the modifier.
469 * Only needed during the first call to this callback at the beginning
470 * of the modifier. In case of subsequent calls asking for value
471 * continuations @a oper is set to #NULL.
472 * @param[out] value_size Where to write the full size of the value.
473 * Only needed during the first call to this callback at the beginning
474 * of the modifier. In case of subsequent calls asking for value
475 * continuations @a value_size is set to #NULL.
476 * @return #GNUNET_SYSERR on error (fatal, aborts transmission)
477 * #GNUNET_NO on success, if more data is to be transmitted later.
478 * Should be used if @a data_size was not big enough to take all the
479 * data for the modifier's value (the name must be always returned
480 * during the first call to this callback).
481 * If 0 is returned in @a data_size the transmission is paused,
482 * and can be resumed with GNUNET_PSYC_master_transmit_resume().
483 * #GNUNET_YES if this completes the modifier (the whole value is supplied).
486 (*GNUNET_PSYC_TransmitNotifyModifier) (void *cls,
490 uint32_t *value_size);
493 * Flags for transmitting messages to a channel by the master.
495 enum GNUNET_PSYC_MasterTransmitFlags
497 GNUNET_PSYC_MASTER_TRANSMIT_NONE = 0,
500 * Whether this message should reset the channel state,
501 * i.e. remove all previously stored state variables.
504 GNUNET_PSYC_MASTER_TRANSMIT_STATE_RESET = 1 << 0,
507 * Whether this message contains any state modifiers.
509 GNUNET_PSYC_MASTER_TRANSMIT_STATE_MODIFY = 1 << 1,
512 * Add PSYC header variable with the hash of the current channel state.
514 GNUNET_PSYC_MASTER_TRANSMIT_STATE_HASH = 1 << 2,
517 * Whether we need to increment the group generation counter after
518 * transmitting this message.
520 GNUNET_PSYC_MASTER_TRANSMIT_INC_GROUP_GEN = 1 << 3
525 * Handle for a pending PSYC transmission operation.
527 struct GNUNET_PSYC_MasterTransmitHandle;
531 * Send a message to call a method to all members in the PSYC channel.
533 * @param master Handle to the PSYC channel.
534 * @param method_name Which method should be invoked.
535 * @param notify_mod Function to call to obtain modifiers.
536 * @param notify_data Function to call to obtain fragments of the data.
537 * @param notify_cls Closure for @a notify_mod and @a notify_data.
538 * @param flags Flags for the message being transmitted.
539 * @return Transmission handle, NULL on error (i.e. more than one request queued).
541 struct GNUNET_PSYC_MasterTransmitHandle *
542 GNUNET_PSYC_master_transmit (struct GNUNET_PSYC_Master *master,
543 const char *method_name,
544 GNUNET_PSYC_TransmitNotifyModifier notify_mod,
545 GNUNET_PSYC_TransmitNotifyData notify_data,
547 enum GNUNET_PSYC_MasterTransmitFlags flags);
551 * Resume transmission to the channel.
553 * @param th Handle of the request that is being resumed.
556 GNUNET_PSYC_master_transmit_resume (struct GNUNET_PSYC_MasterTransmitHandle *th);
560 * Abort transmission request to channel.
562 * @param th Handle of the request that is being aborted.
565 GNUNET_PSYC_master_transmit_cancel (struct GNUNET_PSYC_MasterTransmitHandle *th);
569 * Stop a PSYC master channel.
571 * @param master PSYC channel master to stop.
574 GNUNET_PSYC_master_stop (struct GNUNET_PSYC_Master *master);
578 * Handle for a PSYC channel slave.
580 struct GNUNET_PSYC_Slave;
584 * Function called after the slave connected to the PSYC service.
586 * @param cls Closure.
587 * @param max_message_id Last message ID sent to the channel.
590 (*GNUNET_PSYC_SlaveConnectCallback) (void *cls, uint64_t max_message_id);
594 * Method called to inform about the decision in response to a join request.
596 * If @a is_admitted is not #GNUNET_YES, then sending messages to the channel is
597 * not possible, but earlier history can be still queried.
599 * @param cls Closure.
600 * @param is_admitted #GNUNET_YES or #GNUNET_NO or #GNUNET_SYSERR
601 * @param join_msg Application-dependent join message from the origin.
604 (*GNUNET_PSYC_JoinDecisionCallback) (void *cls,
607 GNUNET_PSYC_MessageHeader *join_msg);
611 * Join a PSYC channel.
613 * The entity joining is always the local peer. The user must immediately use
614 * the GNUNET_PSYC_slave_transmit() functions to transmit a @e join_msg to the
615 * channel; if the join request succeeds, the channel state (and @e recent
616 * method calls) will be replayed to the joining member. There is no explicit
617 * notification on failure (as the channel may simply take days to approve,
618 * and disapproval is simply being ignored).
620 * @param cfg Configuration to use.
621 * @param channel_key ECC public key that identifies the channel we wish to join.
622 * @param slave_key ECC private-public key pair that identifies the slave, and
623 * used by multicast to sign the join request and subsequent unicast
624 * requests sent to the master.
625 * @param origin Peer identity of the origin.
626 * @param relay_count Number of peers in the @a relays array.
627 * @param relays Peer identities of members of the multicast group, which serve
628 * as relays and used to join the group at.
629 * @param message_cb Function to invoke on message parts received from the
630 * channel, typically at least contains method handlers for @e join and
632 * @param slave_connect_cb Function invoked once we have connected to the
634 * @param join_decision_cb Function invoked once we have received a join
636 * @param cls Closure for @a message_cb and @a slave_joined_cb.
637 * @param method_name Method name for the join request.
638 * @param env Environment containing transient variables for the request, or NULL.
639 * @param data Payload for the join message.
640 * @param data_size Number of bytes in @a data.
642 * @return Handle for the slave, NULL on error.
644 struct GNUNET_PSYC_Slave *
645 GNUNET_PSYC_slave_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
646 const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
647 const struct GNUNET_CRYPTO_EddsaPrivateKey *slave_key,
648 const struct GNUNET_PeerIdentity *origin,
649 uint32_t relay_count,
650 const struct GNUNET_PeerIdentity *relays,
651 GNUNET_PSYC_MessageCallback message_cb,
652 GNUNET_PSYC_SlaveConnectCallback slave_connect_cb,
653 GNUNET_PSYC_JoinDecisionCallback join_decision_cb,
655 const char *method_name,
656 const struct GNUNET_ENV_Environment *env,
662 * Part a PSYC channel.
664 * Will terminate the connection to the PSYC service. Polite clients should
665 * first explicitly send a part request (via GNUNET_PSYC_slave_transmit()).
667 * @param slave Slave handle.
670 GNUNET_PSYC_slave_part (struct GNUNET_PSYC_Slave *slave);
674 * Flags for transmitting messages to the channel master by a slave.
676 enum GNUNET_PSYC_SlaveTransmitFlags
678 GNUNET_PSYC_SLAVE_TRANSMIT_NONE = 0
683 * Handle for a pending PSYC transmission operation.
685 struct GNUNET_PSYC_SlaveTransmitHandle;
689 * Request a message to be sent to the channel master.
691 * @param slave Slave handle.
692 * @param method_name Which (PSYC) method should be invoked (on host).
693 * @param notify_mod Function to call to obtain modifiers.
694 * @param notify_data Function to call to obtain fragments of the data.
695 * @param notify_cls Closure for @a notify.
696 * @param flags Flags for the message being transmitted.
697 * @return Transmission handle, NULL on error (i.e. more than one request queued).
699 struct GNUNET_PSYC_SlaveTransmitHandle *
700 GNUNET_PSYC_slave_transmit (struct GNUNET_PSYC_Slave *slave,
701 const char *method_name,
702 GNUNET_PSYC_TransmitNotifyModifier notify_mod,
703 GNUNET_PSYC_TransmitNotifyData notify_data,
705 enum GNUNET_PSYC_SlaveTransmitFlags flags);
709 * Resume transmission to the master.
711 * @param th Handle of the request that is being resumed.
714 GNUNET_PSYC_slave_transmit_resume (struct GNUNET_PSYC_SlaveTransmitHandle *th);
718 * Abort transmission request to master.
720 * @param th Handle of the request that is being aborted.
723 GNUNET_PSYC_slave_transmit_cancel (struct GNUNET_PSYC_SlaveTransmitHandle *th);
727 * Handle to access PSYC channel operations for both the master and slaves.
729 struct GNUNET_PSYC_Channel;
733 * Convert a channel @a master to a @e channel handle to access the @e channel
736 * @param master Channel master handle.
737 * @return Channel handle, valid for as long as @a master is valid.
739 struct GNUNET_PSYC_Channel *
740 GNUNET_PSYC_master_get_channel (struct GNUNET_PSYC_Master *master);
744 * Convert @a slave to a @e channel handle to access the @e channel APIs.
746 * @param slave Slave handle.
747 * @return Channel handle, valid for as long as @a slave is valid.
749 struct GNUNET_PSYC_Channel *
750 GNUNET_PSYC_slave_get_channel (struct GNUNET_PSYC_Slave *slave);
754 * Add a slave to the channel's membership list.
756 * Note that this will NOT generate any PSYC traffic, it will merely update the
757 * local database to modify how we react to <em>membership test</em> queries.
758 * The channel master still needs to explicitly transmit a @e join message to
759 * notify other channel members and they then also must still call this function
760 * in their respective methods handling the @e join message. This way, how @e
761 * join and @e part operations are exactly implemented is still up to the
762 * application; for example, there might be a @e part_all method to kick out
765 * Note that channel slaves are explicitly trusted to execute such methods
766 * correctly; not doing so correctly will result in either denying other slaves
767 * access or offering access to channel data to non-members.
769 * @param channel Channel handle.
770 * @param slave_key Identity of channel slave to add.
771 * @param announced_at ID of the message that announced the membership change.
772 * @param effective_since Addition of slave is in effect since this message ID.
775 GNUNET_PSYC_channel_slave_add (struct GNUNET_PSYC_Channel *channel,
776 const struct GNUNET_CRYPTO_EddsaPublicKey *slave_key,
777 uint64_t announced_at,
778 uint64_t effective_since);
782 * Remove a slave from the channel's membership list.
784 * Note that this will NOT generate any PSYC traffic, it will merely update the
785 * local database to modify how we react to <em>membership test</em> queries.
786 * The channel master still needs to explicitly transmit a @e part message to
787 * notify other channel members and they then also must still call this function
788 * in their respective methods handling the @e part message. This way, how
789 * @e join and @e part operations are exactly implemented is still up to the
790 * application; for example, there might be a @e part_all message to kick out
793 * Note that channel members are explicitly trusted to perform these
794 * operations correctly; not doing so correctly will result in either
795 * denying members access or offering access to channel data to
798 * @param channel Channel handle.
799 * @param slave_key Identity of channel slave to remove.
800 * @param announced_at ID of the message that announced the membership change.
803 GNUNET_PSYC_channel_slave_remove (struct GNUNET_PSYC_Channel *channel,
804 const struct GNUNET_CRYPTO_EddsaPublicKey
806 uint64_t announced_at);
810 * Function called to inform a member about stored state values for a channel.
812 * @param cls Closure.
813 * @param name Name of the state variable. A NULL value indicates that there
814 * are no more state variables to be returned.
815 * @param value Value of the state variable.
816 * @param value_size Number of bytes in @a value.
819 (*GNUNET_PSYC_StateCallback) (void *cls,
826 * Function called when a requested operation has finished.
828 * @param cls Closure.
831 (*GNUNET_PSYC_FinishCallback) (void *cls);
835 * Handle to a story telling operation.
837 struct GNUNET_PSYC_Story;
841 * Request to be told the message history of the channel.
843 * Historic messages (but NOT the state at the time) will be replayed (given to
844 * the normal method handlers) if available and if access is permitted.
846 * To get the latest message, use 0 for both the start and end message ID.
848 * @param channel Which channel should be replayed?
849 * @param start_message_id Earliest interesting point in history.
850 * @param end_message_id Last (exclusive) interesting point in history.
851 * @param message_cb Function to invoke on message parts received from the story.
852 * @param finish_cb Function to call when the requested story has been fully
853 * told (counting message IDs might not suffice, as some messages
854 * might be secret and thus the listener would not know the story is
855 * finished without being told explicitly); once this function
856 * has been called, the client must not call
857 * GNUNET_PSYC_channel_story_tell_cancel() anymore.
858 * @param cls Closure for the callbacks.
859 * @return Handle to cancel story telling operation.
861 struct GNUNET_PSYC_Story *
862 GNUNET_PSYC_channel_story_tell (struct GNUNET_PSYC_Channel *channel,
863 uint64_t start_message_id,
864 uint64_t end_message_id,
865 GNUNET_PSYC_MessageCallback message_cb,
866 GNUNET_PSYC_FinishCallback finish_cb,
871 * Abort story telling.
873 * This function must not be called from within method handlers (as given to
874 * GNUNET_PSYC_slave_join()) of the slave.
876 * @param story Story telling operation to stop.
879 GNUNET_PSYC_channel_story_tell_cancel (struct GNUNET_PSYC_Story *story);
883 * Handle for a state query operation.
885 struct GNUNET_PSYC_StateQuery;
889 * Retrieve the best matching channel state variable.
891 * If the requested variable name is not present in the state, the nearest
892 * less-specific name is matched; for example, requesting "_a_b" will match "_a"
893 * if "_a_b" does not exist.
895 * @param channel Channel handle.
896 * @param full_name Full name of the requested variable, the actual variable
897 * returned might have a shorter name..
898 * @param cb Function called once when a matching state variable is found.
899 * Not called if there's no matching state variable.
900 * @param cb_cls Closure for the callbacks.
901 * @return Handle that can be used to cancel the query operation.
903 struct GNUNET_PSYC_StateQuery *
904 GNUNET_PSYC_channel_state_get (struct GNUNET_PSYC_Channel *channel,
905 const char *full_name,
906 GNUNET_PSYC_StateCallback cb,
911 * Return all channel state variables whose name matches a given prefix.
913 * A name matches if it starts with the given @a name_prefix, thus requesting
914 * the empty prefix ("") will match all values; requesting "_a_b" will also
915 * return values stored under "_a_b_c".
917 * The @a state_cb is invoked on all matching state variables asynchronously, as
918 * the state is stored in and retrieved from the PSYCstore,
920 * @param channel Channel handle.
921 * @param name_prefix Prefix of the state variable name to match.
922 * @param cb Function to call with the matching state variables.
923 * @param cb_cls Closure for the callbacks.
924 * @return Handle that can be used to cancel the query operation.
926 struct GNUNET_PSYC_StateQuery *
927 GNUNET_PSYC_channel_state_get_prefix (struct GNUNET_PSYC_Channel *channel,
928 const char *name_prefix,
929 GNUNET_PSYC_StateCallback cb,
934 * Cancel a state query operation.
936 * @param query Handle for the operation to cancel.
939 GNUNET_PSYC_channel_state_get_cancel (struct GNUNET_PSYC_StateQuery *query);
942 #if 0 /* keep Emacsens' auto-indent happy */
949 /* ifndef GNUNET_PSYC_SERVICE_H */
951 /* end of gnunet_psyc_service.h */