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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 requesting to join.
330 * @param method_name Method name in the join request.
331 * @param variable_count Number of elements in the @a variables array.
332 * @param variables Transient variables for the join request.
333 * @param data Data stream given to the method (might not be zero-terminated
334 * if data is binary).
335 * @param data_size Number of bytes in @a data.
336 * @param jh Join handle to use with GNUNET_PSYC_join_decision()
339 (*GNUNET_PSYC_JoinCallback) (void *cls,
340 const struct GNUNET_CRYPTO_EddsaPublicKey
342 const char *method_name,
343 size_t variable_count,
344 const struct GNUNET_ENV_Modifier *variables,
347 struct GNUNET_PSYC_JoinHandle *jh);
351 * Function to call with the decision made for a join request.
353 * Must be called once and only once in response to an invocation of the
354 * #GNUNET_PSYC_JoinCallback.
356 * @param jh Join request handle.
357 * @param is_admitted #GNUNET_YES if joining is approved,
358 * #GNUNET_NO if it is disapproved.
359 * @param relay_count Number of relays given.
360 * @param relays Array of suggested peers that might be useful relays to use
361 * when joining the multicast group (essentially a list of peers that
362 * are already part of the multicast group and might thus be willing
363 * to help with routing). If empty, only this local peer (which must
364 * be the multicast origin) is a good candidate for building the
365 * multicast tree. Note that it is unnecessary to specify our own
366 * peer identity in this array.
367 * @param method_name Method name for the message transmitted with the response.
368 * @param env Environment containing transient variables for the message,
370 * @param data Data of the message.
371 * @param data_size Size of @a data.
374 GNUNET_PSYC_join_decision (struct GNUNET_PSYC_JoinHandle *jh,
376 uint32_t relay_count,
377 const struct GNUNET_PeerIdentity *relays,
378 const char *method_name,
379 const struct GNUNET_ENV_Environment *env,
385 * Handle for the master of a PSYC channel.
387 struct GNUNET_PSYC_Master;
391 * Function called after the channel master started.
393 * @param cls Closure.
394 * @param max_message_id Last message ID sent to the channel.
397 (*GNUNET_PSYC_MasterStartCallback) (void *cls, uint64_t max_message_id);
401 * Start a PSYC master channel.
403 * Will start a multicast group identified by the given ECC key. Messages
404 * received from group members will be given to the respective handler methods.
405 * If a new member wants to join a group, the "join" method handler will be
406 * invoked; the join handler must then generate a "join" message to approve the
407 * joining of the new member. The channel can also change group membership
408 * without explicit requests. Note that PSYC doesn't itself "understand" join
409 * or part messages, the respective methods must call other PSYC functions to
410 * inform PSYC about the meaning of the respective events.
412 * @param cfg Configuration to use (to connect to PSYC service).
413 * @param channel_key ECC key that will be used to sign messages for this
414 * PSYC session. The public key is used to identify the PSYC channel.
415 * Note that end-users will usually not use the private key directly, but
416 * rather look it up in GNS for places managed by other users, or select
417 * a file with the private key(s) when setting up their own channels
418 * FIXME: we'll likely want to use NOT the p521 curve here, but a cheaper
420 * @param policy Channel policy specifying join and history restrictions.
421 * Used to automate join decisions.
422 * @param message_cb Function to invoke on message parts received from slaves.
423 * @param join_cb Function to invoke when a peer wants to join.
424 * @param master_started_cb Function to invoke after the channel master started.
425 * @param cls Closure for @a method and @a join_cb.
426 * @return Handle for the channel master, NULL on error.
428 struct GNUNET_PSYC_Master *
429 GNUNET_PSYC_master_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
430 const struct GNUNET_CRYPTO_EddsaPrivateKey *channel_key,
431 enum GNUNET_PSYC_Policy policy,
432 GNUNET_PSYC_MessageCallback message_cb,
433 GNUNET_PSYC_JoinCallback join_cb,
434 GNUNET_PSYC_MasterStartCallback master_started_cb,
439 * Function called to provide data for a transmission via PSYC.
441 * Note that returning #GNUNET_YES or #GNUNET_SYSERR (but not #GNUNET_NO)
442 * invalidates the respective transmission handle.
444 * @param cls Closure.
445 * @param[in,out] data_size Initially set to the number of bytes available in
446 * @a data, should be set to the number of bytes written to data.
447 * @param[out] data Where to write the body of the message to give to the
448 * method. The function must copy at most @a data_size bytes to @a data.
449 * @return #GNUNET_SYSERR on error (fatal, aborts transmission)
450 * #GNUNET_NO on success, if more data is to be transmitted later.
451 * Should be used if @a data_size was not big enough to take all the
452 * data. If 0 is returned in @a data_size the transmission is paused,
453 * and can be resumed with GNUNET_PSYC_master_transmit_resume().
454 * #GNUNET_YES if this completes the transmission (all data supplied)
457 (*GNUNET_PSYC_TransmitNotifyData) (void *cls,
462 * Function called to provide a modifier for a transmission via PSYC.
464 * Note that returning #GNUNET_YES or #GNUNET_SYSERR (but not #GNUNET_NO)
465 * invalidates the respective transmission handle.
467 * @param cls Closure.
468 * @param[in,out] data_size Initially set to the number of bytes available in
469 * @a data, should be set to the number of bytes written to data.
470 * @param[out] data Where to write the modifier's name and value.
471 * The function must copy at most @a data_size bytes to @a data.
472 * When this callback is first called for a modifier, @a data should
473 * contain: "name\0value". If the whole value does not fit, subsequent
474 * calls to this function should write continuations of the value to
476 * @param[out] oper Where to write the operator of the modifier.
477 * Only needed during the first call to this callback at the beginning
478 * of the modifier. In case of subsequent calls asking for value
479 * continuations @a oper is set to #NULL.
480 * @param[out] value_size Where to write the full size of the value.
481 * Only needed during the first call to this callback at the beginning
482 * of the modifier. In case of subsequent calls asking for value
483 * continuations @a value_size is set to #NULL.
484 * @return #GNUNET_SYSERR on error (fatal, aborts transmission)
485 * #GNUNET_NO on success, if more data is to be transmitted later.
486 * Should be used if @a data_size was not big enough to take all the
487 * data for the modifier's value (the name must be always returned
488 * during the first call to this callback).
489 * If 0 is returned in @a data_size the transmission is paused,
490 * and can be resumed with GNUNET_PSYC_master_transmit_resume().
491 * #GNUNET_YES if this completes the modifier (the whole value is supplied).
494 (*GNUNET_PSYC_TransmitNotifyModifier) (void *cls,
498 uint32_t *value_size);
501 * Flags for transmitting messages to a channel by the master.
503 enum GNUNET_PSYC_MasterTransmitFlags
505 GNUNET_PSYC_MASTER_TRANSMIT_NONE = 0,
508 * Whether this message should reset the channel state,
509 * i.e. remove all previously stored state variables.
512 GNUNET_PSYC_MASTER_TRANSMIT_STATE_RESET = 1 << 0,
515 * Whether this message contains any state modifiers.
517 GNUNET_PSYC_MASTER_TRANSMIT_STATE_MODIFY = 1 << 1,
520 * Add PSYC header variable with the hash of the current channel state.
522 GNUNET_PSYC_MASTER_TRANSMIT_STATE_HASH = 1 << 2,
525 * Whether we need to increment the group generation counter after
526 * transmitting this message.
528 GNUNET_PSYC_MASTER_TRANSMIT_INC_GROUP_GEN = 1 << 3
533 * Handle for a pending PSYC transmission operation.
535 struct GNUNET_PSYC_MasterTransmitHandle;
539 * Send a message to call a method to all members in the PSYC channel.
541 * @param master Handle to the PSYC channel.
542 * @param method_name Which method should be invoked.
543 * @param notify_mod Function to call to obtain modifiers.
544 * @param notify_data Function to call to obtain fragments of the data.
545 * @param notify_cls Closure for @a notify_mod and @a notify_data.
546 * @param flags Flags for the message being transmitted.
547 * @return Transmission handle, NULL on error (i.e. more than one request queued).
549 struct GNUNET_PSYC_MasterTransmitHandle *
550 GNUNET_PSYC_master_transmit (struct GNUNET_PSYC_Master *master,
551 const char *method_name,
552 GNUNET_PSYC_TransmitNotifyModifier notify_mod,
553 GNUNET_PSYC_TransmitNotifyData notify_data,
555 enum GNUNET_PSYC_MasterTransmitFlags flags);
559 * Resume transmission to the channel.
561 * @param th Handle of the request that is being resumed.
564 GNUNET_PSYC_master_transmit_resume (struct GNUNET_PSYC_MasterTransmitHandle *th);
568 * Abort transmission request to channel.
570 * @param th Handle of the request that is being aborted.
573 GNUNET_PSYC_master_transmit_cancel (struct GNUNET_PSYC_MasterTransmitHandle *th);
577 * Stop a PSYC master channel.
579 * @param master PSYC channel master to stop.
582 GNUNET_PSYC_master_stop (struct GNUNET_PSYC_Master *master);
586 * Handle for a PSYC channel slave.
588 struct GNUNET_PSYC_Slave;
592 * Function called after the slave joined.
594 * @param cls Closure.
595 * @param max_message_id Last message ID sent to the channel.
598 (*GNUNET_PSYC_SlaveJoinCallback) (void *cls, uint64_t max_message_id);
602 * Join a PSYC channel.
604 * The entity joining is always the local peer. The user must immediately use
605 * the GNUNET_PSYC_slave_transmit() functions to transmit a @e join_msg to the
606 * channel; if the join request succeeds, the channel state (and @e recent
607 * method calls) will be replayed to the joining member. There is no explicit
608 * notification on failure (as the channel may simply take days to approve,
609 * and disapproval is simply being ignored).
611 * @param cfg Configuration to use.
612 * @param channel_key ECC public key that identifies the channel we wish to join.
613 * @param slave_key ECC private-public key pair that identifies the slave, and
614 * used by multicast to sign the join request and subsequent unicast
615 * requests sent to the master.
616 * @param origin Peer identity of the origin.
617 * @param relay_count Number of peers in the @a relays array.
618 * @param relays Peer identities of members of the multicast group, which serve
619 * as relays and used to join the group at.
620 * @param message_cb Function to invoke on message parts received from the
621 * channel, typically at least contains method handlers for @e join and
623 * @param join_cb function invoked once we have joined with the current
624 * message ID of the channel
625 * @param slave_joined_cb Function to invoke when a peer wants to join.
626 * @param cls Closure for @a message_cb and @a slave_joined_cb.
627 * @param method_name Method name for the join request.
628 * @param env Environment containing transient variables for the request, or NULL.
629 * @param data Payload for the join message.
630 * @param data_size Number of bytes in @a data.
631 * @return Handle for the slave, NULL on error.
633 struct GNUNET_PSYC_Slave *
634 GNUNET_PSYC_slave_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
635 const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
636 const struct GNUNET_CRYPTO_EddsaPrivateKey *slave_key,
637 const struct GNUNET_PeerIdentity *origin,
638 uint32_t relay_count,
639 const struct GNUNET_PeerIdentity *relays,
640 GNUNET_PSYC_MessageCallback message_cb,
641 GNUNET_PSYC_JoinCallback join_cb,
642 GNUNET_PSYC_SlaveJoinCallback slave_joined_cb,
644 const char *method_name,
645 const struct GNUNET_ENV_Environment *env,
651 * Part a PSYC channel.
653 * Will terminate the connection to the PSYC service. Polite clients should
654 * first explicitly send a part request (via GNUNET_PSYC_slave_transmit()).
656 * @param slave Slave handle.
659 GNUNET_PSYC_slave_part (struct GNUNET_PSYC_Slave *slave);
663 * Flags for transmitting messages to the channel master by a slave.
665 enum GNUNET_PSYC_SlaveTransmitFlags
667 GNUNET_PSYC_SLAVE_TRANSMIT_NONE = 0
672 * Handle for a pending PSYC transmission operation.
674 struct GNUNET_PSYC_SlaveTransmitHandle;
678 * Request a message to be sent to the channel master.
680 * @param slave Slave handle.
681 * @param method_name Which (PSYC) method should be invoked (on host).
682 * @param notify_mod Function to call to obtain modifiers.
683 * @param notify_data Function to call to obtain fragments of the data.
684 * @param notify_cls Closure for @a notify.
685 * @param flags Flags for the message being transmitted.
686 * @return Transmission handle, NULL on error (i.e. more than one request queued).
688 struct GNUNET_PSYC_SlaveTransmitHandle *
689 GNUNET_PSYC_slave_transmit (struct GNUNET_PSYC_Slave *slave,
690 const char *method_name,
691 GNUNET_PSYC_TransmitNotifyModifier notify_mod,
692 GNUNET_PSYC_TransmitNotifyData notify_data,
694 enum GNUNET_PSYC_SlaveTransmitFlags flags);
698 * Resume transmission to the master.
700 * @param th Handle of the request that is being resumed.
703 GNUNET_PSYC_slave_transmit_resume (struct GNUNET_PSYC_SlaveTransmitHandle *th);
707 * Abort transmission request to master.
709 * @param th Handle of the request that is being aborted.
712 GNUNET_PSYC_slave_transmit_cancel (struct GNUNET_PSYC_SlaveTransmitHandle *th);
716 * Handle to access PSYC channel operations for both the master and slaves.
718 struct GNUNET_PSYC_Channel;
722 * Convert a channel @a master to a @e channel handle to access the @e channel
725 * @param master Channel master handle.
726 * @return Channel handle, valid for as long as @a master is valid.
728 struct GNUNET_PSYC_Channel *
729 GNUNET_PSYC_master_get_channel (struct GNUNET_PSYC_Master *master);
733 * Convert @a slave to a @e channel handle to access the @e channel APIs.
735 * @param slave Slave handle.
736 * @return Channel handle, valid for as long as @a slave is valid.
738 struct GNUNET_PSYC_Channel *
739 GNUNET_PSYC_slave_get_channel (struct GNUNET_PSYC_Slave *slave);
743 * Add a slave to the channel's membership list.
745 * Note that this will NOT generate any PSYC traffic, it will merely update the
746 * local database to modify how we react to <em>membership test</em> queries.
747 * The channel master still needs to explicitly transmit a @e join message to
748 * notify other channel members and they then also must still call this function
749 * in their respective methods handling the @e join message. This way, how @e
750 * join and @e part operations are exactly implemented is still up to the
751 * application; for example, there might be a @e part_all method to kick out
754 * Note that channel slaves are explicitly trusted to execute such methods
755 * correctly; not doing so correctly will result in either denying other slaves
756 * access or offering access to channel data to non-members.
758 * @param channel Channel handle.
759 * @param slave_key Identity of channel slave to add.
760 * @param announced_at ID of the message that announced the membership change.
761 * @param effective_since Addition of slave is in effect since this message ID.
764 GNUNET_PSYC_channel_slave_add (struct GNUNET_PSYC_Channel *channel,
765 const struct GNUNET_CRYPTO_EddsaPublicKey *slave_key,
766 uint64_t announced_at,
767 uint64_t effective_since);
771 * Remove a slave from the channel's membership list.
773 * Note that this will NOT generate any PSYC traffic, it will merely update the
774 * local database to modify how we react to <em>membership test</em> queries.
775 * The channel master still needs to explicitly transmit a @e part message to
776 * notify other channel members and they then also must still call this function
777 * in their respective methods handling the @e part message. This way, how
778 * @e join and @e part operations are exactly implemented is still up to the
779 * application; for example, there might be a @e part_all message to kick out
782 * Note that channel members are explicitly trusted to perform these
783 * operations correctly; not doing so correctly will result in either
784 * denying members access or offering access to channel data to
787 * @param channel Channel handle.
788 * @param slave_key Identity of channel slave to remove.
789 * @param announced_at ID of the message that announced the membership change.
792 GNUNET_PSYC_channel_slave_remove (struct GNUNET_PSYC_Channel *channel,
793 const struct GNUNET_CRYPTO_EddsaPublicKey
795 uint64_t announced_at);
799 * Function called to inform a member about stored state values for a channel.
801 * @param cls Closure.
802 * @param name Name of the state variable. A NULL value indicates that there
803 * are no more state variables to be returned.
804 * @param value Value of the state variable.
805 * @param value_size Number of bytes in @a value.
808 (*GNUNET_PSYC_StateCallback) (void *cls,
815 * Function called when a requested operation has finished.
817 * @param cls Closure.
820 (*GNUNET_PSYC_FinishCallback) (void *cls);
824 * Handle to a story telling operation.
826 struct GNUNET_PSYC_Story;
830 * Request to be told the message history of the channel.
832 * Historic messages (but NOT the state at the time) will be replayed (given to
833 * the normal method handlers) if available and if access is permitted.
835 * To get the latest message, use 0 for both the start and end message ID.
837 * @param channel Which channel should be replayed?
838 * @param start_message_id Earliest interesting point in history.
839 * @param end_message_id Last (exclusive) interesting point in history.
840 * @param message_cb Function to invoke on message parts received from the story.
841 * @param finish_cb Function to call when the requested story has been fully
842 * told (counting message IDs might not suffice, as some messages
843 * might be secret and thus the listener would not know the story is
844 * finished without being told explicitly); once this function
845 * has been called, the client must not call
846 * GNUNET_PSYC_channel_story_tell_cancel() anymore.
847 * @param cls Closure for the callbacks.
848 * @return Handle to cancel story telling operation.
850 struct GNUNET_PSYC_Story *
851 GNUNET_PSYC_channel_story_tell (struct GNUNET_PSYC_Channel *channel,
852 uint64_t start_message_id,
853 uint64_t end_message_id,
854 GNUNET_PSYC_MessageCallback message_cb,
855 GNUNET_PSYC_FinishCallback finish_cb,
860 * Abort story telling.
862 * This function must not be called from within method handlers (as given to
863 * GNUNET_PSYC_slave_join()) of the slave.
865 * @param story Story telling operation to stop.
868 GNUNET_PSYC_channel_story_tell_cancel (struct GNUNET_PSYC_Story *story);
872 * Handle for a state query operation.
874 struct GNUNET_PSYC_StateQuery;
878 * Retrieve the best matching channel state variable.
880 * If the requested variable name is not present in the state, the nearest
881 * less-specific name is matched; for example, requesting "_a_b" will match "_a"
882 * if "_a_b" does not exist.
884 * @param channel Channel handle.
885 * @param full_name Full name of the requested variable, the actual variable
886 * returned might have a shorter name..
887 * @param cb Function called once when a matching state variable is found.
888 * Not called if there's no matching state variable.
889 * @param cb_cls Closure for the callbacks.
890 * @return Handle that can be used to cancel the query operation.
892 struct GNUNET_PSYC_StateQuery *
893 GNUNET_PSYC_channel_state_get (struct GNUNET_PSYC_Channel *channel,
894 const char *full_name,
895 GNUNET_PSYC_StateCallback cb,
900 * Return all channel state variables whose name matches a given prefix.
902 * A name matches if it starts with the given @a name_prefix, thus requesting
903 * the empty prefix ("") will match all values; requesting "_a_b" will also
904 * return values stored under "_a_b_c".
906 * The @a state_cb is invoked on all matching state variables asynchronously, as
907 * the state is stored in and retrieved from the PSYCstore,
909 * @param channel Channel handle.
910 * @param name_prefix Prefix of the state variable name to match.
911 * @param cb Function to call with the matching state variables.
912 * @param cb_cls Closure for the callbacks.
913 * @return Handle that can be used to cancel the query operation.
915 struct GNUNET_PSYC_StateQuery *
916 GNUNET_PSYC_channel_state_get_prefix (struct GNUNET_PSYC_Channel *channel,
917 const char *name_prefix,
918 GNUNET_PSYC_StateCallback cb,
923 * Cancel a state query operation.
925 * @param query Handle for the operation to cancel.
928 GNUNET_PSYC_channel_state_get_cancel (struct GNUNET_PSYC_StateQuery *query);
931 #if 0 /* keep Emacsens' auto-indent happy */
938 /* ifndef GNUNET_PSYC_SERVICE_H */
940 /* end of gnunet_psyc_service.h */