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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
174 GNUNET_NETWORK_STRUCT_BEGIN
177 * Header of a PSYC message.
179 struct GNUNET_PSYC_MessageHeader
182 * Generic message header with size and type information.
184 struct GNUNET_MessageHeader header;
187 * Flags for this message fragment.
189 * @see enum GNUNET_PSYC_MessageFlags
191 uint32_t flags GNUNET_PACKED;
194 * Number of the message this message part belongs to.
195 * Monotonically increasing from 1.
197 uint64_t message_id GNUNET_PACKED;
200 * Sending slave's public key.
201 * Not set if the message is from the master.
203 struct GNUNET_CRYPTO_EddsaPublicKey slave_key;
205 /* Followed by concatenated PSYC message parts:
206 * messages with GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_* types
212 * The method of a message.
214 struct GNUNET_PSYC_MessageMethod
217 * Type: GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_METHOD
219 struct GNUNET_MessageHeader header;
222 * OR'ed GNUNET_PSYC_MasterTransmitFlags
224 uint32_t flags GNUNET_PACKED;
226 /* Followed by NUL-terminated method name. */
231 * A modifier of a message.
233 struct GNUNET_PSYC_MessageModifier
236 * Type: GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MODIFIER
238 struct GNUNET_MessageHeader header;
243 uint32_t value_size GNUNET_PACKED;
246 * Size of name, including NUL terminator.
248 uint16_t name_size GNUNET_PACKED;
251 * enum GNUNET_ENV_Operator
255 /* Followed by NUL-terminated name, then the value. */
258 GNUNET_NETWORK_STRUCT_END
261 #define GNUNET_PSYC_MODIFIER_MAX_PAYLOAD \
262 GNUNET_MULTICAST_FRAGMENT_MAX_PAYLOAD \
263 - sizeof (struct GNUNET_PSYC_MessageModifier)
265 #define GNUNET_PSYC_MOD_CONT_MAX_PAYLOAD \
266 GNUNET_MULTICAST_FRAGMENT_MAX_PAYLOAD \
267 - sizeof (struct GNUNET_MessageHeader)
269 #define GNUNET_PSYC_DATA_MAX_PAYLOAD \
270 GNUNET_MULTICAST_FRAGMENT_MAX_PAYLOAD \
271 - sizeof (struct GNUNET_MessageHeader)
275 * Handle that identifies a join request.
277 * Used to match calls to #GNUNET_PSYC_JoinCallback to the
278 * corresponding calls to GNUNET_PSYC_join_decision().
280 struct GNUNET_PSYC_JoinHandle;
284 * Method called from PSYC upon receiving part of a message.
286 * @param cls Closure.
287 * @param msg Message part, one of the following types:
288 * - GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_HEADER
289 * - GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_METHOD
290 * - GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MODIFIER
291 * - GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_MOD_CONT
292 * - GNUNET_MESSAGE_TYPE_PSYC_MESSAGE_DATA
295 (*GNUNET_PSYC_MessageCallback) (void *cls,
298 const struct GNUNET_MessageHeader *msg);
302 * Method called from PSYC upon receiving a join request.
304 * @param cls Closure.
305 * @param slave requesting to join.
306 * @param method_name Method name in the join request.
307 * @param variable_count Number of elements in the @a variables array.
308 * @param variables Transient variables for the join request.
309 * @param data Data stream given to the method (might not be zero-terminated
310 * if data is binary).
311 * @param data_size Number of bytes in @a data.
312 * @param jh Join handle to use with GNUNET_PSYC_join_decision()
315 (*GNUNET_PSYC_JoinCallback) (void *cls,
316 const struct GNUNET_CRYPTO_EddsaPublicKey
318 const char *method_name,
319 size_t variable_count,
320 const struct GNUNET_ENV_Modifier *variables,
323 struct GNUNET_PSYC_JoinHandle *jh);
327 * Function to call with the decision made for a join request.
329 * Must be called once and only once in response to an invocation of the
330 * #GNUNET_PSYC_JoinCallback.
332 * @param jh Join request handle.
333 * @param is_admitted #GNUNET_YES if joining is approved,
334 * #GNUNET_NO if it is disapproved.
335 * @param relay_count Number of relays given.
336 * @param relays Array of suggested peers that might be useful relays to use
337 * when joining the multicast group (essentially a list of peers that
338 * are already part of the multicast group and might thus be willing
339 * to help with routing). If empty, only this local peer (which must
340 * be the multicast origin) is a good candidate for building the
341 * multicast tree. Note that it is unnecessary to specify our own
342 * peer identity in this array.
343 * @param method_name Method name for the message transmitted with the response.
344 * @param env Environment containing transient variables for the message,
346 * @param data Data of the message.
347 * @param data_size Size of @a data.
350 GNUNET_PSYC_join_decision (struct GNUNET_PSYC_JoinHandle *jh,
352 uint32_t relay_count,
353 const struct GNUNET_PeerIdentity *relays,
354 const char *method_name,
355 const struct GNUNET_ENV_Environment *env,
361 * Handle for the master of a PSYC channel.
363 struct GNUNET_PSYC_Master;
367 * Function called after the channel master started.
369 * @param cls Closure.
370 * @param max_message_id Last message ID sent to the channel.
373 (*GNUNET_PSYC_MasterStartCallback) (void *cls, uint64_t max_message_id);
377 * Start a PSYC master channel.
379 * Will start a multicast group identified by the given ECC key. Messages
380 * received from group members will be given to the respective handler methods.
381 * If a new member wants to join a group, the "join" method handler will be
382 * invoked; the join handler must then generate a "join" message to approve the
383 * joining of the new member. The channel can also change group membership
384 * without explicit requests. Note that PSYC doesn't itself "understand" join
385 * or part messages, the respective methods must call other PSYC functions to
386 * inform PSYC about the meaning of the respective events.
388 * @param cfg Configuration to use (to connect to PSYC service).
389 * @param channel_key ECC key that will be used to sign messages for this
390 * PSYC session. The public key is used to identify the PSYC channel.
391 * Note that end-users will usually not use the private key directly, but
392 * rather look it up in GNS for places managed by other users, or select
393 * a file with the private key(s) when setting up their own channels
394 * FIXME: we'll likely want to use NOT the p521 curve here, but a cheaper
396 * @param policy Channel policy specifying join and history restrictions.
397 * Used to automate join decisions.
398 * @param message_cb Function to invoke on message parts received from slaves.
399 * @param join_cb Function to invoke when a peer wants to join.
400 * @param master_started_cb Function to invoke after the channel master started.
401 * @param cls Closure for @a method and @a join_cb.
402 * @return Handle for the channel master, NULL on error.
404 struct GNUNET_PSYC_Master *
405 GNUNET_PSYC_master_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
406 const struct GNUNET_CRYPTO_EddsaPrivateKey *channel_key,
407 enum GNUNET_PSYC_Policy policy,
408 GNUNET_PSYC_MessageCallback message_cb,
409 GNUNET_PSYC_JoinCallback join_cb,
410 GNUNET_PSYC_MasterStartCallback master_started_cb,
415 * Function called to provide data for a transmission via PSYC.
417 * Note that returning #GNUNET_YES or #GNUNET_SYSERR (but not #GNUNET_NO)
418 * invalidates the respective transmission handle.
420 * @param cls Closure.
421 * @param[in,out] data_size Initially set to the number of bytes available in
422 * @a data, should be set to the number of bytes written to data.
423 * @param[out] data Where to write the body of the message to give to the
424 * method. The function must copy at most @a data_size bytes to @a data.
425 * @return #GNUNET_SYSERR on error (fatal, aborts transmission)
426 * #GNUNET_NO on success, if more data is to be transmitted later.
427 * Should be used if @a data_size was not big enough to take all the
428 * data. If 0 is returned in @a data_size the transmission is paused,
429 * and can be resumed with GNUNET_PSYC_master_transmit_resume().
430 * #GNUNET_YES if this completes the transmission (all data supplied)
433 (*GNUNET_PSYC_TransmitNotifyData) (void *cls,
438 * Function called to provide a modifier for a transmission via PSYC.
440 * Note that returning #GNUNET_YES or #GNUNET_SYSERR (but not #GNUNET_NO)
441 * invalidates the respective transmission handle.
443 * @param cls Closure.
444 * @param[in,out] data_size Initially set to the number of bytes available in
445 * @a data, should be set to the number of bytes written to data.
446 * @param[out] data Where to write the modifier's name and value.
447 * The function must copy at most @a data_size bytes to @a data.
448 * When this callback is first called for a modifier, @a data should
449 * contain: "name\0value". If the whole value does not fit, subsequent
450 * calls to this function should write continuations of the value to
452 * @param[out] oper Where to write the operator of the modifier.
453 * Only needed during the first call to this callback at the beginning
454 * of the modifier. In case of subsequent calls asking for value
455 * continuations @a oper is set to #NULL.
456 * @param[out] value_size Where to write the full size of the value.
457 * Only needed during the first call to this callback at the beginning
458 * of the modifier. In case of subsequent calls asking for value
459 * continuations @a value_size is set to #NULL.
460 * @return #GNUNET_SYSERR on error (fatal, aborts transmission)
461 * #GNUNET_NO on success, if more data is to be transmitted later.
462 * Should be used if @a data_size was not big enough to take all the
463 * data for the modifier's value (the name must be always returned
464 * during the first call to this callback).
465 * If 0 is returned in @a data_size the transmission is paused,
466 * and can be resumed with GNUNET_PSYC_master_transmit_resume().
467 * #GNUNET_YES if this completes the modifier (the whole value is supplied).
470 (*GNUNET_PSYC_TransmitNotifyModifier) (void *cls,
474 uint32_t *value_size);
477 * Flags for transmitting messages to a channel by the master.
479 enum GNUNET_PSYC_MasterTransmitFlags
481 GNUNET_PSYC_MASTER_TRANSMIT_NONE = 0,
483 * Whether this message should reset the channel state,
484 * i.e. remove all previously stored state variables.
486 GNUNET_PSYC_MASTER_TRANSMIT_RESET_STATE = 1 << 0,
489 * Whether we need to increment the group generation counter after
490 * transmitting this message.
492 GNUNET_PSYC_MASTER_TRANSMIT_INC_GROUP_GEN = 1 << 1,
495 * Add PSYC header variable with the hash of the current channel state.
497 GNUNET_PSYC_MASTER_TRANSMIT_ADD_STATE_HASH = 1 << 2
502 * Handle for a pending PSYC transmission operation.
504 struct GNUNET_PSYC_MasterTransmitHandle;
508 * Send a message to call a method to all members in the PSYC channel.
510 * @param master Handle to the PSYC channel.
511 * @param method_name Which method should be invoked.
512 * @param notify_mod Function to call to obtain modifiers.
513 * @param notify_data Function to call to obtain fragments of the data.
514 * @param notify_cls Closure for @a notify_mod and @a notify_data.
515 * @param flags Flags for the message being transmitted.
516 * @return Transmission handle, NULL on error (i.e. more than one request queued).
518 struct GNUNET_PSYC_MasterTransmitHandle *
519 GNUNET_PSYC_master_transmit (struct GNUNET_PSYC_Master *master,
520 const char *method_name,
521 GNUNET_PSYC_TransmitNotifyModifier notify_mod,
522 GNUNET_PSYC_TransmitNotifyData notify_data,
524 enum GNUNET_PSYC_MasterTransmitFlags flags);
528 * Resume transmission to the channel.
530 * @param th Handle of the request that is being resumed.
533 GNUNET_PSYC_master_transmit_resume (struct GNUNET_PSYC_MasterTransmitHandle *th);
537 * Abort transmission request to channel.
539 * @param th Handle of the request that is being aborted.
542 GNUNET_PSYC_master_transmit_cancel (struct GNUNET_PSYC_MasterTransmitHandle *th);
546 * Stop a PSYC master channel.
548 * @param master PSYC channel master to stop.
551 GNUNET_PSYC_master_stop (struct GNUNET_PSYC_Master *master);
555 * Handle for a PSYC channel slave.
557 struct GNUNET_PSYC_Slave;
561 * Function called after the slave joined.
563 * @param cls Closure.
564 * @param max_message_id Last message ID sent to the channel.
567 (*GNUNET_PSYC_SlaveJoinCallback) (void *cls, uint64_t max_message_id);
571 * Join a PSYC channel.
573 * The entity joining is always the local peer. The user must immediately use
574 * the GNUNET_PSYC_slave_transmit() functions to transmit a @e join_msg to the
575 * channel; if the join request succeeds, the channel state (and @e recent
576 * method calls) will be replayed to the joining member. There is no explicit
577 * notification on failure (as the channel may simply take days to approve,
578 * and disapproval is simply being ignored).
580 * @param cfg Configuration to use.
581 * @param channel_key ECC public key that identifies the channel we wish to join.
582 * @param slave_key ECC private-public key pair that identifies the slave, and
583 * used by multicast to sign the join request and subsequent unicast
584 * requests sent to the master.
585 * @param origin Peer identity of the origin.
586 * @param relay_count Number of peers in the @a relays array.
587 * @param relays Peer identities of members of the multicast group, which serve
588 * as relays and used to join the group at.
589 * @param message_cb Function to invoke on message parts received from the
590 * channel, typically at least contains method handlers for @e join and
592 * @param join_cb function invoked once we have joined with the current
593 * message ID of the channel
594 * @param slave_joined_cb Function to invoke when a peer wants to join.
595 * @param cls Closure for @a message_cb and @a slave_joined_cb.
596 * @param method_name Method name for the join request.
597 * @param env Environment containing transient variables for the request, or NULL.
598 * @param data Payload for the join message.
599 * @param data_size Number of bytes in @a data.
600 * @return Handle for the slave, NULL on error.
602 struct GNUNET_PSYC_Slave *
603 GNUNET_PSYC_slave_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
604 const struct GNUNET_CRYPTO_EddsaPublicKey *channel_key,
605 const struct GNUNET_CRYPTO_EddsaPrivateKey *slave_key,
606 const struct GNUNET_PeerIdentity *origin,
607 uint32_t relay_count,
608 const struct GNUNET_PeerIdentity *relays,
609 GNUNET_PSYC_MessageCallback message_cb,
610 GNUNET_PSYC_JoinCallback join_cb,
611 GNUNET_PSYC_SlaveJoinCallback slave_joined_cb,
613 const char *method_name,
614 const struct GNUNET_ENV_Environment *env,
620 * Part a PSYC channel.
622 * Will terminate the connection to the PSYC service. Polite clients should
623 * first explicitly send a part request (via GNUNET_PSYC_slave_transmit()).
625 * @param slave Slave handle.
628 GNUNET_PSYC_slave_part (struct GNUNET_PSYC_Slave *slave);
632 * Flags for transmitting messages to the channel master by a slave.
634 enum GNUNET_PSYC_SlaveTransmitFlags
636 GNUNET_PSYC_SLAVE_TRANSMIT_NONE = 0
641 * Handle for a pending PSYC transmission operation.
643 struct GNUNET_PSYC_SlaveTransmitHandle;
647 * Request a message to be sent to the channel master.
649 * @param slave Slave handle.
650 * @param method_name Which (PSYC) method should be invoked (on host).
651 * @param notify_mod Function to call to obtain modifiers.
652 * @param notify_data Function to call to obtain fragments of the data.
653 * @param notify_cls Closure for @a notify.
654 * @param flags Flags for the message being transmitted.
655 * @return Transmission handle, NULL on error (i.e. more than one request queued).
657 struct GNUNET_PSYC_SlaveTransmitHandle *
658 GNUNET_PSYC_slave_transmit (struct GNUNET_PSYC_Slave *slave,
659 const char *method_name,
660 GNUNET_PSYC_TransmitNotifyModifier notify_mod,
661 GNUNET_PSYC_TransmitNotifyData notify_data,
663 enum GNUNET_PSYC_SlaveTransmitFlags flags);
667 * Resume transmission to the master.
669 * @param th Handle of the request that is being resumed.
672 GNUNET_PSYC_slave_transmit_resume (struct GNUNET_PSYC_SlaveTransmitHandle *th);
676 * Abort transmission request to master.
678 * @param th Handle of the request that is being aborted.
681 GNUNET_PSYC_slave_transmit_cancel (struct GNUNET_PSYC_SlaveTransmitHandle *th);
685 * Handle to access PSYC channel operations for both the master and slaves.
687 struct GNUNET_PSYC_Channel;
691 * Convert a channel @a master to a @e channel handle to access the @e channel
694 * @param master Channel master handle.
695 * @return Channel handle, valid for as long as @a master is valid.
697 struct GNUNET_PSYC_Channel *
698 GNUNET_PSYC_master_get_channel (struct GNUNET_PSYC_Master *master);
702 * Convert @a slave to a @e channel handle to access the @e channel APIs.
704 * @param slave Slave handle.
705 * @return Channel handle, valid for as long as @a slave is valid.
707 struct GNUNET_PSYC_Channel *
708 GNUNET_PSYC_slave_get_channel (struct GNUNET_PSYC_Slave *slave);
712 * Add a slave to the channel's membership list.
714 * Note that this will NOT generate any PSYC traffic, it will merely update the
715 * local database to modify how we react to <em>membership test</em> queries.
716 * The channel master still needs to explicitly transmit a @e join message to
717 * notify other channel members and they then also must still call this function
718 * in their respective methods handling the @e join message. This way, how @e
719 * join and @e part operations are exactly implemented is still up to the
720 * application; for example, there might be a @e part_all method to kick out
723 * Note that channel slaves are explicitly trusted to execute such methods
724 * correctly; not doing so correctly will result in either denying other slaves
725 * access or offering access to channel data to non-members.
727 * @param channel Channel handle.
728 * @param slave_key Identity of channel slave to add.
729 * @param announced_at ID of the message that announced the membership change.
730 * @param effective_since Addition of slave is in effect since this message ID.
733 GNUNET_PSYC_channel_slave_add (struct GNUNET_PSYC_Channel *channel,
734 const struct GNUNET_CRYPTO_EddsaPublicKey *slave_key,
735 uint64_t announced_at,
736 uint64_t effective_since);
740 * Remove a slave from the channel's membership list.
742 * Note that this will NOT generate any PSYC traffic, it will merely update the
743 * local database to modify how we react to <em>membership test</em> queries.
744 * The channel master still needs to explicitly transmit a @e part message to
745 * notify other channel members and they then also must still call this function
746 * in their respective methods handling the @e part message. This way, how
747 * @e join and @e part operations are exactly implemented is still up to the
748 * application; for example, there might be a @e part_all message to kick out
751 * Note that channel members are explicitly trusted to perform these
752 * operations correctly; not doing so correctly will result in either
753 * denying members access or offering access to channel data to
756 * @param channel Channel handle.
757 * @param slave_key Identity of channel slave to remove.
758 * @param announced_at ID of the message that announced the membership change.
761 GNUNET_PSYC_channel_slave_remove (struct GNUNET_PSYC_Channel *channel,
762 const struct GNUNET_CRYPTO_EddsaPublicKey
764 uint64_t announced_at);
768 * Function called to inform a member about stored state values for a channel.
770 * @param cls Closure.
771 * @param name Name of the state variable. A NULL value indicates that there
772 * are no more state variables to be returned.
773 * @param value Value of the state variable.
774 * @param value_size Number of bytes in @a value.
777 (*GNUNET_PSYC_StateCallback) (void *cls,
784 * Function called when a requested operation has finished.
786 * @param cls Closure.
789 (*GNUNET_PSYC_FinishCallback) (void *cls);
793 * Handle to a story telling operation.
795 struct GNUNET_PSYC_Story;
799 * Request to be told the message history of the channel.
801 * Historic messages (but NOT the state at the time) will be replayed (given to
802 * the normal method handlers) if available and if access is permitted.
804 * To get the latest message, use 0 for both the start and end message ID.
806 * @param channel Which channel should be replayed?
807 * @param start_message_id Earliest interesting point in history.
808 * @param end_message_id Last (exclusive) interesting point in history.
809 * @param message_cb Function to invoke on message parts received from the story.
810 * @param finish_cb Function to call when the requested story has been fully
811 * told (counting message IDs might not suffice, as some messages
812 * might be secret and thus the listener would not know the story is
813 * finished without being told explicitly); once this function
814 * has been called, the client must not call
815 * GNUNET_PSYC_channel_story_tell_cancel() anymore.
816 * @param cls Closure for the callbacks.
817 * @return Handle to cancel story telling operation.
819 struct GNUNET_PSYC_Story *
820 GNUNET_PSYC_channel_story_tell (struct GNUNET_PSYC_Channel *channel,
821 uint64_t start_message_id,
822 uint64_t end_message_id,
823 GNUNET_PSYC_MessageCallback message_cb,
824 GNUNET_PSYC_FinishCallback finish_cb,
829 * Abort story telling.
831 * This function must not be called from within method handlers (as given to
832 * GNUNET_PSYC_slave_join()) of the slave.
834 * @param story Story telling operation to stop.
837 GNUNET_PSYC_channel_story_tell_cancel (struct GNUNET_PSYC_Story *story);
841 * Handle for a state query operation.
843 struct GNUNET_PSYC_StateQuery;
847 * Retrieve the best matching channel state variable.
849 * If the requested variable name is not present in the state, the nearest
850 * less-specific name is matched; for example, requesting "_a_b" will match "_a"
851 * if "_a_b" does not exist.
853 * @param channel Channel handle.
854 * @param full_name Full name of the requested variable, the actual variable
855 * returned might have a shorter name..
856 * @param cb Function called once when a matching state variable is found.
857 * Not called if there's no matching state variable.
858 * @param cb_cls Closure for the callbacks.
859 * @return Handle that can be used to cancel the query operation.
861 struct GNUNET_PSYC_StateQuery *
862 GNUNET_PSYC_channel_state_get (struct GNUNET_PSYC_Channel *channel,
863 const char *full_name,
864 GNUNET_PSYC_StateCallback cb,
869 * Return all channel state variables whose name matches a given prefix.
871 * A name matches if it starts with the given @a name_prefix, thus requesting
872 * the empty prefix ("") will match all values; requesting "_a_b" will also
873 * return values stored under "_a_b_c".
875 * The @a state_cb is invoked on all matching state variables asynchronously, as
876 * the state is stored in and retrieved from the PSYCstore,
878 * @param channel Channel handle.
879 * @param name_prefix Prefix of the state variable name to match.
880 * @param cb Function to call with the matching state variables.
881 * @param cb_cls Closure for the callbacks.
882 * @return Handle that can be used to cancel the query operation.
884 struct GNUNET_PSYC_StateQuery *
885 GNUNET_PSYC_channel_state_get_prefix (struct GNUNET_PSYC_Channel *channel,
886 const char *name_prefix,
887 GNUNET_PSYC_StateCallback cb,
892 * Cancel a state query operation.
894 * @param query Handle for the operation to cancel.
897 GNUNET_PSYC_channel_state_get_cancel (struct GNUNET_PSYC_StateQuery *query);
900 #if 0 /* keep Emacsens' auto-indent happy */
907 /* ifndef GNUNET_PSYC_SERVICE_H */
909 /* end of gnunet_psyc_service.h */