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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
33 * - this API does not know about psyc's "root" and "places";
34 * there is no 'root' in GNUnet-Psyc as we're decentralized;
35 * 'places' and 'persons' are combined within the same
36 * abstraction, that of a "channel". Channels are identified
37 * and accessed in this API using a public/private key.
38 * Higher-level applications should use NAMES within GADS
39 * to obtain public keys, and the distinction between
40 * 'places' and 'persons' can then be made with the help
41 * of the naming system (and/or conventions).
42 * Channels are (as in PSYC) organized into a hierarchy; each
43 * channel owner (the one with the private key) is then
44 * the operator of the multicast group (its Origin in
45 * the terminology of the multicast API).
46 * - The API supports passing large amounts of data using
47 * 'streaming' for the argument passed to a method. State
48 * and variables must fit into memory and cannot be streamed
49 * (thus, no passing of 4 GB of data in a variable;
50 * once we implement this, we might want to create a
51 * #define for the maximum size of a variable).
52 * - PSYC defines standard variables, methods, etc. This
53 * library deliberately abstracts over all of these; a
54 * higher-level API should combine the naming system (GADS)
55 * and standard methods (message, join, leave, warn,
56 * fail, error) and variables (action, color, time,
57 * tag, etc.). However, this API does take over the
58 * routing variables, specifically 'context' (channel),
59 * and 'source'. We only kind-of support 'target', as
60 * the target is either everyone in the group or the
61 * origin, and never just a single member of the group;
62 * for such individual messages, an application needs to
63 * construct an 'inbox' channel where the owner (only)
64 * receives messages (but never forwards; private responses
65 * would be transmitted by joining the senders 'inbox'
66 * channel -- or a inbox#bob subchannel). The
67 * goal for all of this is to keep the abstractions in this
68 * API minimal: interaction with multicast, try \& slice,
69 * state/variable/channel management. Higher-level
70 * operations belong elsewhere (so maybe this API should
71 * be called 'PSYC-low', whereas a higher-level API
72 * implementing defaults for standard methods and
73 * variables might be called 'PSYC-std' or 'PSYC-high'.
76 #ifndef GNUNET_PSYC_SERVICE_H
77 #define GNUNET_PSYC_SERVICE_H
82 #if 0 /* keep Emacsens' auto-indent happy */
87 #include "gnunet_util_lib.h"
88 #include "gnunet_multicast_service.h"
92 * Version number of GNUnet-PSYC API.
94 #define GNUNET_PSYC_VERSION 0x00000000
98 * Method called from PSYC upon receiving a message indicating a call
102 * @param full_method_name original method name from PSYC (may be more
103 * specific than the registered method name due to try-and-slice matching)
104 * @param sender who transmitted the message (origin, except for messages
105 * from one of the members to the origin)
106 * @param message_id unique message counter for this message;
107 * (unique only in combination with the given sender for
109 * @param group_generation group generation counter for this message
110 * (always zero for messages from members to channel owner)
111 * @param data_size number of bytes in 'data'
112 * @param data data stream given to the method (might not be zero-terminated
115 typedef int (*GNUNET_PSYC_Method)(void *cls,
116 const char *full_method_name,
117 const struct GNUNET_PeerIdentity *sender,
119 uint64_t group_generation,
125 * Handle for the channel of a PSYC group.
127 struct GNUNET_PSYC_Channel;
131 * Start a PSYC channel. Will create a multicast group identified by
132 * the given ECC key. Messages recevied from group members will be
133 * given to the respective handler methods. If a new member wants to
134 * join a group, the "join" method handler will be invoked; the join
135 * handler must then generate a "join" message to approve the joining
136 * of the new member. The channel can also change group membership
137 * without explicit requests. Note that PSYC doesn't itself "understand"
138 * join or leave messages, the respective methods must call other
139 * PSYC functions to inform PSYC about the meaning of the respective
142 * @param cfg configuration to use (to connect to PSYC service)
143 * @param name name of the channel, only important if this is a subchannel
144 * @param method_count number of methods in 'methods' array
145 * @param methods functions to invoke on messages received from members,
146 * typcially at least contains functions for 'join' and 'leave'.
147 * @param priv_key ECC key that will be used to sign messages for this
148 * PSYC session; public key is used to identify the
149 * PSYC group; FIXME: we'll likely want to use
150 * NOT the p521 curve here, but a cheaper one in the future
151 * Note that end-users will usually not use the private key
152 * directly, but rather look it up in GADS for groups
153 * managed by other users, or select a file with the private
154 * key(s) when setting up their own channels
155 * @param join_policy what is the membership policy of the group?
156 * Used to automate group management decisions.
157 * @return handle for the channel, NULL on error
159 struct GNUNET_PSYC_Channel *
160 GNUNET_PSYC_channel_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
162 unsigned int method_count,
163 const struct GNUNET_PSYC_Method *methods,
164 const struct GNUNET_CRYPTO_EccPrivateKey *priv_key,
165 enum GNUNET_MULTICAST_JoinPolicy join_policy);
169 * Possible operations on PSYC state (persistent) and variables (per message).
171 enum GNUNET_PSYC_Operator
174 * Replace the full state with the new value ("=").
176 GNUNET_PSYC_SOT_SET_STATE = 0,
179 * Delete the complete entry from the state (given data must be
180 * empty). Equivalent to 'SET' with emtpy data, but more
183 GNUNET_PSYC_SOT_DELETE = 0,
186 * Set the value of a variable to a new value (":").
188 GNUNET_PSYC_SOT_SET_VARIABLE,
191 * Add the given value to the set of values in the state ("+").
193 GNUNET_PSYC_SOT_ADD_STATE,
196 * Remove the given value from the set of values in the state ("-").
198 GNUNET_PSYC_SOT_REMOVE_STATE
204 * Update channel state (or set a variable). The state of a channel
205 * must fit into the memory of each member (and the channel); large
206 * values that require streaming must only be passed as the stream
207 * arguments to methods. State updates might not be transmitted to
208 * group members until the next call to
209 * 'GNUNET_PSYC_channel_broadcast_call_method'. Variable updates must
210 * be given just before the call to the respective method that needs
213 * @param channel handle to the PSYC group / channel
214 * @param full_state_name name of the field in the channel state to change
215 * @param type kind of update operation (add, remove, replace, delete)
216 * @param data_size number of bytes in data
217 * @param data new state value
218 * @return GNUNET_OK on success, GNUNET_SYSERR on internal error
219 * (i.e. state too large)
222 GNUNET_PSYC_channel_update (struct GNUNET_PSYC_Channel *channel,
223 const char *full_state_name,
224 enum GNUNET_PSYC_Operator type,
230 * Function called to provide data for a transmission via PSYC. Note
231 * that returning GNUNET_OK or GNUNET_SYSERR (but not GNUNET_NO)
232 * invalidates the respective transmission handle.
235 * @param message_id set to the unique message ID that was generated for
237 * @param group_generation set to the group generation used for this
239 * @param data_size initially set to the number of bytes available in 'data',
240 * should be set to the number of bytes written to data (IN/OUT)
241 * @param data where to write the body of the message to give to the method;
242 * function must copy at most '*data_size' bytes to 'data'.
243 * @return GNUNET_SYSERR on error (fatal, aborts transmission)
244 * GNUNET_NO on success, if more data is to be transmitted later
245 * (should be used if 'data_size' was not big enough to take all the data)
246 * GNUNET_OK if this completes the transmission (all data supplied)
248 typedef int (*GNUNET_PSYC_ChannelReadyNotify)(void *cls,
250 uint64_t group_generation,
256 * Handle for a pending PSYC transmission operation.
258 struct GNUNET_PSYC_ChannelTransmitHandle;
262 * Send a message to call a method to all members in the PSYC channel.
264 * @param channel handle to the PSYC multicast group
265 * @param increment_group_generation GNUNET_YES if we need to increment
266 * the group generation counter after transmitting this message
267 * @param full_method_name which method should be invoked
268 * @param notify function to call to obtain the arguments
269 * @param notify_cls closure for 'notify'
270 * @return transmission handle, NULL on error (i.e. more than one request queued)
272 struct GNUNET_PSYC_ChannelTransmitHandle *
273 GNUNET_PSYC_channel_notify_transmit_ready (struct GNUNET_PSYC_Channel *channel,
274 int increment_group_generation,
275 const char *full_method_name,
276 GNUNET_PSYC_ChannelReadyNotify notify,
281 * Abort transmission request to channel.
283 * @param th handle of the request that is being aborted
286 GNUNET_PSYC_channel_notify_transmit_ready_cancel (struct GNUNET_PSYC_ChannelTransmitHandle *th);
290 * End a PSYC channel.
292 * @param channel PSYC channel to terminate
295 GNUNET_PSYC_channel_end (struct GNUNET_PSYC_Channel *channel);
299 * Handle to access PSYC group operations for all members.
301 struct GNUNET_PSYC_Group;
305 * Convert 'channel' to a 'group' handle to access the 'group' APIs.
307 * @param channel channel handle
308 * @return group handle, valid for as long as 'channel' is valid
310 struct GNUNET_PSYC_Group *
311 GNUNET_PSYC_channel_get_group (struct GNUNET_PSYC_Channel *channel);
315 * Convert 'member' to a 'group' handle to access the 'group' APIs.
317 * @param member membership handle
318 * @return group handle, valid for as long as 'member' is valid
320 struct GNUNET_PSYC_Group *
321 GNUNET_PSYC_member_get_group (struct GNUNET_PSYC_Member *member);
325 * Add a member to the group. Note that this will NOT generate any
326 * PSYC traffic, it will merely update the local data base to modify
327 * how we react to 'membership test' queries. The channel still needs to
328 * explicitly transmit a 'join' message to notify other group members
329 * and they then also must still call this function in their respective
330 * methods handling the 'join' message. This way, how 'join' and 'leave'
331 * operations are exactly implemented is still up to the application;
332 * for example, there might be a 'leave_all' method to kick out everyone.
334 * Note that group members are explicitly trusted to execute such
335 * methods correctly; not doing so correctly will result in either
336 * denying members access or offering access to group data to
339 * @param group group handle
340 * @param member which peer to add
341 * @param message_id message ID for the message that changed the membership
342 * @param group_generation the generation ID where the change went into effect
345 GNUNET_PSYC_group_member_admit (struct GNUNET_PSYC_Group *group,
346 const struct GNUNET_PeerIdentity *member,
348 uint64_t group_generation);
352 * Remove a member from the group. Note that this will NOT generate any
353 * PSYC traffic, it will merely update the local data base to modify
354 * how we react to 'membership test' queries. The channel still needs to
355 * explicitly transmit a 'leave' message to notify other group members
356 * and they then also must still call this function in their respective
357 * methods handling the 'leave' message. This way, how 'join' and 'leave'
358 * operations are exactly implemented is still up to the application;
359 * for example, there might be a 'leave_all' message to kick out everyone.
361 * Note that group members are explicitly trusted to perform these
362 * operations correctly; not doing so correctly will result in either
363 * denying members access or offering access to group data to
366 * @param group group handle
367 * @param member which peer to remove
368 * @param message_id message ID for the message that changed the membership
369 * @param group_generation the generation ID where the change went into effect
372 GNUNET_PSYC_group_member_kick (struct GNUNET_PSYC_Group *group,
373 const struct GNUNET_PeerIdentity *member,
375 uint64_t group_generation);
379 * Function called to inform a member about state changes for a
380 * channel. Note that (for sets) only the delta is communicated, not
384 * @param full_state_name full name of the state
385 * @param type how to interpret the change
386 * @param state_value information about the new state
387 * @param state_value_size number of bytes in 'state_value'
389 typedef void (*GNUNET_PSYC_StateCallback)(void *cls,
390 const char *full_state_name,
391 enum GNUNET_PSYC_Operator type,
392 const void *state_value,
393 size_t state_value_size);
397 * Descriptor for an event handler handling PSYC state updates.
399 struct GNUNET_PSYC_StateHandler
403 * Name of the state this handler calls about, used in try-and-slice matching.
405 const char *state_name;
408 * Function to call whenever the respective state changes.
410 GNUNET_PSYC_StateCallback event_handler;
413 * Closure for the 'event_handler' function.
415 void *event_handler_cls;
421 * Join a PSYC group. The entity joining is always the local peer.
422 * The user must immediately use the 'GNUNET_PSYC_member_send_to_host'
423 * (and possibly 'GNUNET_PSYC_member_host_variable_set') functions to
424 * transmit a 'join_msg' to the channel; if the join request succeeds,
425 * the channel state (and 'recent' method calls) will be replayed to
426 * the joining member. There is no explicit notification on failure
427 * (as the channel may simply take days to approve, and disapproval is
428 * simply being ignored).
430 * @param cfg configuration to use
431 * @param pub_key ECC key that identifies the channel we wish to join
432 * @param method_count number of methods in 'methods' array
433 * @param methods functions to invoke on messages received from the channel,
434 * typcially at least contains functions for 'join' and 'leave'.
435 * @param state_count number of state handlers
436 * @param state_handlers array of state event handlers
437 * @return handle for the member, NULL on error
439 struct GNUNET_PSYC_Member *
440 GNUNET_PSYC_member_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
441 const struct GNUNET_CRYPTO_EccPublicKey *pub_key,
442 unsigned int method_count,
443 const struct GNUNET_PSYC_Method *methods,
444 unsigned int state_count,
445 struct GNUNET_PSYC_StateHandler *state_handlers);
449 * Leave a multicast group. Will terminate the connection to the PSYC
450 * service. Polite clients should first explicitly send a 'leave'
451 * request (via 'GNUNET_PSYC_member_send_to_host').
453 * @param member membership handle
456 GNUNET_PSYC_member_leave (struct GNUNET_PSYC_Member *member);
460 * Function called to provide data for a transmission to the channel
461 * owner (aka the 'host' of the channel). Note that returning
462 * GNUNET_OK or GNUNET_SYSERR (but not GNUNET_NO) invalidates the
463 * respective transmission handle.
466 * @param data_size initially set to the number of bytes available in 'data',
467 * should be set to the number of bytes written to data (IN/OUT)
468 * @param data where to write the body of the message to give to the method;
469 * function must copy at most '*data_size' bytes to 'data'.
470 * @return GNUNET_SYSERR on error (fatal, aborts transmission)
471 * GNUNET_NO on success, if more data is to be transmitted later
472 * GNUNET_OK if this completes the transmission (all data supplied)
474 typedef int (*GNUNET_PSYC_HostReadyNotify)(void *cls,
480 * Handle for a pending PSYC transmission operation.
482 struct GNUNET_PSYC_HostTransmitHandle;
486 * Request a message to be send to the channel host.
488 * @param member membership handle
489 * @param method_name which (PSYC) method should be invoked (on host)
490 * @param notify function to call when we are allowed to transmit (to get data)
491 * @param notify_cls closure for 'notify'
492 * @return transmission handle, NULL on error (i.e. more than one request queued)
494 struct GNUNET_PSYC_HostTransmitHandle *
495 GNUNET_PSYC_member_send_to_host (struct GNUNET_PSYC_Member *member,
496 const char *method_name,
497 GNUNET_PSYC_HostReadyNotify notify,
502 * Set a (temporary, ":") variable for the next message being transmitted
503 * via 'GNUNET_PSYC_member_send_to_host'. If 'GNUNET_PSYC_member_send_to_host'
504 * is called and then cancelled, all variables that were set using this
505 * function will be unset (lost/forgotten). To clear a variable state after
506 * setting it, you can also call this function again with NULL/0 for the value.
508 * @param member membership handle
509 * @param variable_name name of the variable to set
510 * @param value value to set for the given variable
511 * @param value_size number of bytes in 'value'
514 GNUNET_PSYC_member_host_variable_set (struct GNUNET_PSYC_Member *member,
515 const char *variable_name,
521 * Abort transmission request to host.
523 * @param th handle of the request that is being aborted
526 GNUNET_PSYC_member_send_to_host_cancel (struct GNUNET_PSYC_HostTransmitHandle *th);
530 * Handle to a story telling operation.
532 struct GNUNET_PSYC_Story;
536 * Request to be told the message history of the channel. Historic
537 * messages (but NOT the state at the time) will be replayed (given to
538 * the normal method handlers) if available and if access is
541 * @param member which channel should be replayed?
542 * @param start earliest interesting point in history
543 * @param end last (exclusive) interesting point in history
544 * @param finish_cb function to call when the requested story has been fully
545 * told (counting message IDs might not suffice, as some messages
546 * might be secret and thus the listener would not know the story is
547 * finished without being told explicitly); once this function
548 * has been called, the client must not call
549 * 'GNUNET_PSYC_member_story_tell_cancel' anymore
550 * @param finish_cb_cls closure to finish_cb
551 * @return handle to cancel story telling operation
553 struct GNUNET_PSYC_Story *
554 GNUNET_PSYC_member_story_tell (struct GNUNET_PSYC_Member *member,
557 void (*finish_cb)(void *),
558 void *finish_cb_cls);
562 * Abort story telling. This function must not be called from within
563 * method handlers (as given to 'GNUNET_PSYC_member_join') of the
566 * @param story story telling operation to stop
569 GNUNET_PSYC_member_story_tell_cancel (struct GNUNET_PSYC_Story *story);
573 * Call the given callback on all matching values (including
574 * variables) in the channel state. The callback is invoked
575 * synchronously on all matching states (as the state is fully
576 * replicated in the library in this process; channel states should be
577 * small, large data is to be passed as streaming data to methods).
579 * A name matches if it includes the 'state_name' prefix, thus
580 * requesting the empty state ("") will match all values; requesting
581 * "a_b" will also return values stored under "a_b_c".
583 * @param member membership handle
584 * @param state_name name of the state to query (full name
585 * might be longer, this is only the prefix that must match)
586 * @param cb function to call on the matching state values
587 * @param cb_cls closure for 'cb'
588 * @return message ID for which the state was returned (last seen
592 GNUNET_PSYC_member_state_get_all (struct GNUNET_PSYC_Member *member,
593 const char *state_name,
594 GNUNET_PSYC_StateCallback cb,
599 * Obtain the current value of the best-matching value in the state
600 * (including variables). Note that variables are only valid during a
601 * GNUNET_PSYC_Method invocation, as variables are only valid for the
602 * duration of a method invocation.
604 * If the requested variable name does not have an exact state in
605 * the state, the nearest less-specific name is matched; for example,
606 * requesting "a_b" will match "a" if "a_b" does not exist.
608 * @param member membership handle
609 * @param variable_name name of the variable to query
610 * @param return_value_size set to number of bytes in variable,
611 * needed as variables might contain binary data and
612 * might also not be 0-terminated; set to 0 on errors
613 * @return NULL on error (no matching state or variable), pointer
614 to the respective value otherwise
617 GNUNET_PSYC_member_state_get (struct GNUNET_PSYC_Member *member,
618 const char *variable_name,
619 size_t *return_value_size);
623 #if 0 /* keep Emacsens' auto-indent happy */
630 /* ifndef GNUNET_PSYC_SERVICE_H */
632 /* end of gnunet_psyc_service.h */