2 This file is part of GNUnet.
3 (C) 2012, 2013 Christian Grothoff (and other contributing authors)
5 GNUnet is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 3, or (at your
8 option) any later version.
10 GNUnet is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with GNUnet; see the file COPYING. If not, write to the
17 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA.
22 * @file include/gnunet_psyc_service.h
23 * @brief PSYC service; high-level access to the PSYC protocol
24 * note that clients of this API are NOT expected to
25 * understand the PSYC message format, only the semantics!
26 * Parsing (and serializing) the PSYC stream format is done
27 * within the implementation of the libgnunetpsyc library,
28 * and this API deliberately exposes as little as possible
29 * of the actual data stream format to the application!
30 * @author Christian Grothoff
31 * @author Gabor X Toth
34 * - this API does not know about psyc's "root" and "places";
35 * there is no 'root' in GNUnet-Psyc as we're decentralized;
36 * 'places' and 'persons' are combined within the same
37 * abstraction, that of a "channel". Channels are identified
38 * and accessed in this API using a public/private key.
39 * Higher-level applications should use NAMES within GADS
40 * to obtain public keys, and the distinction between
41 * 'places' and 'persons' can then be made with the help
42 * of the naming system (and/or conventions).
43 * Channels are (as in PSYC) organized into a hierarchy; each
44 * channel master (the one with the private key) is then
45 * the operator of the multicast group (its Origin in
46 * the terminology of the multicast API).
47 * - The API supports passing large amounts of data using
48 * 'streaming' for the argument passed to a method. State
49 * and variables must fit into memory and cannot be streamed
50 * (thus, no passing of 4 GB of data in a variable;
51 * once we implement this, we might want to create a
52 * @c \#define for the maximum size of a variable).
53 * - PSYC defines standard variables, methods, etc. This
54 * library deliberately abstracts over all of these; a
55 * higher-level API should combine the naming system (GADS)
56 * and standard methods (message, join, part, warn,
57 * fail, error) and variables (action, color, time,
58 * tag, etc.). However, this API does take over the
59 * routing variables, specifically 'context' (channel),
60 * and 'source'. We only kind-of support 'target', as
61 * the target is either everyone in the group or the
62 * origin, and never just a single member of the group;
63 * for such individual messages, an application needs to
64 * construct an 'inbox' channel where the master (only)
65 * receives messages (but never forwards; private responses
66 * would be transmitted by joining the senders 'inbox'
67 * channel -- or a inbox#bob subchannel). The
68 * goal for all of this is to keep the abstractions in this
69 * API minimal: interaction with multicast, try \& slice,
70 * state/variable/channel management. Higher-level
71 * operations belong elsewhere (so maybe this API should
72 * be called 'PSYC-low', whereas a higher-level API
73 * implementing defaults for standard methods and
74 * variables might be called 'PSYC-std' or 'PSYC-high'.
77 #ifndef GNUNET_PSYC_SERVICE_H
78 #define GNUNET_PSYC_SERVICE_H
83 #if 0 /* keep Emacsens' auto-indent happy */
88 #include "gnunet_util_lib.h"
89 #include "gnunet_psyc_lib.h"
90 #include "gnunet_multicast_service.h"
94 * Version number of GNUnet-PSYC API.
96 #define GNUNET_PSYC_VERSION 0x00000000
99 enum GNUNET_PSYC_MessageFlags
102 * First fragment of a message.
104 GNUNET_PSYC_MESSAGE_FIRST_FRAGMENT = 1 << 0,
107 * Last fragment of a message.
109 GNUNET_PSYC_MESSAGE_LAST_FRAGMENT = 1 << 1,
112 * OR'ed flags if message is not fragmented.
114 GNUNET_PSYC_MESSAGE_NOT_FRAGMENTED
115 = GNUNET_PSYC_MESSAGE_FIRST_FRAGMENT
116 | GNUNET_PSYC_MESSAGE_LAST_FRAGMENT,
119 * Historic message, retrieved from PSYCstore.
121 GNUNET_PSYC_MESSAGE_HISTORIC = 1 << 30
126 * Handle that identifies a join request.
128 * Used to match calls to #GNUNET_PSYC_JoinCallback to the
129 * corresponding calls to GNUNET_PSYC_join_decision().
131 struct GNUNET_PSYC_JoinHandle;
135 * Method called from PSYC upon receiving a message indicating a call
138 * @param cls Closure.
139 * @param sender Who transmitted the message (master, except for messages
140 * from one of the slaves to the master).
141 * @param message_id Unique message counter for this message;
142 * (unique only in combination with the given sender for
144 * @param method_name Original method name from PSYC (may be more
145 * specific than the registered method name due to try-and-slice matching).
146 * FIXME: no try-and-slice for methods defined here.
147 * @param header_length Number of modifiers in header.
148 * @param header Modifiers present in the message. FIXME: use environment instead?
149 * @param data_offset Byte offset of @a data in the overall data of the method.
150 * @param data_size Number of bytes in @a data.
151 * @param data Data stream given to the method (might not be zero-terminated
152 * if data is binary).
153 * @param frag Fragmentation status for the data.
155 typedef int (*GNUNET_PSYC_Method)(void *cls,
156 const struct GNUNET_PeerIdentity *sender,
158 const char *method_name,
159 size_t header_length,
160 GNUNET_PSYC_Modifier *header,
161 uint64_t data_offset,
164 enum GNUNET_PSYC_MessageFlags flags);
168 * Method called from PSYC upon receiving a join request.
170 * @param cls Closure.
171 * @param peer Peer requesting to join.
172 * @param method_name Method name in the join request.
173 * @param header_length Number of modifiers in header.
174 * @param header Modifiers present in the message.
175 * @param data_size Number of bytes in @a data.
176 * @param data Data stream given to the method (might not be zero-terminated
177 * if data is binary).
179 typedef int (*GNUNET_PSYC_JoinCallback)(void *cls,
180 const struct GNUNET_PeerIdentity *peer,
181 const char *method_name,
182 size_t header_length,
183 GNUNET_PSYC_Modifier *header,
186 struct GNUNET_PSYC_JoinHandle *jh);
190 * Function to call with the decision made for a join request.
192 * Must be called once and only once in response to an invocation of the
193 * #GNUNET_PSYC_JoinCallback.
195 * @param jh Join request handle.
196 * @param is_admitted #GNUNET_YES if joining is approved,
197 * #GNUNET_NO if it is disapproved
198 * @param method_name Method name for the message transmitted with the response.
199 * @param env Environment containing transient variables for the message, or NULL.
200 * @param data_size Size of @a data.
201 * @param data Data of the message.
204 GNUNET_PSYC_join_decision (struct GNUNET_PSYC_JoinHandle *jh,
206 const char *method_name,
207 const struct GNUNET_ENV_Environment *env,
213 * Handle for the master of a PSYC channel.
215 struct GNUNET_PSYC_Master;
219 * Start a PSYC master channel.
221 * Will start a multicast group identified by the given ECC key. Messages
222 * received from group members will be given to the respective handler methods.
223 * If a new member wants to join a group, the "join" method handler will be
224 * invoked; the join handler must then generate a "join" message to approve the
225 * joining of the new member. The channel can also change group membership
226 * without explicit requests. Note that PSYC doesn't itself "understand" join
227 * or part messages, the respective methods must call other PSYC functions to
228 * inform PSYC about the meaning of the respective events.
230 * @param cfg Configuration to use (to connect to PSYC service).
231 * @param priv_key ECC key that will be used to sign messages for this
232 * PSYC session; public key is used to identify the
233 * PSYC channel; FIXME: we'll likely want to use
234 * NOT the p512 curve here, but a cheaper one in the future
235 * Note that end-users will usually not use the private key
236 * directly, but rather look it up in GADS for places
237 * managed by other users, or select a file with the private
238 * key(s) when setting up their own channels
239 * @param join_policy What is the membership policy of the group?
240 * Used to automate group management decisions.
241 * @param method_cb Function to invoke on messages received from members.
242 * @param join_cb Function to invoke when a peer wants to join.
243 * @param cls Closure for the callbacks.
244 * @return Handle for the channel master, NULL on error.
246 struct GNUNET_PSYC_Master *
247 GNUNET_PSYC_master_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
248 const struct GNUNET_CRYPTO_EccPrivateKey *priv_key,
249 enum GNUNET_MULTICAST_JoinPolicy join_policy,
250 GNUNET_PSYC_Method method_cb,
251 GNUNET_PSYC_JoinCallback join_cb,
256 * Function called to provide data for a transmission via PSYC.
258 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
259 * invalidates the respective transmission handle.
261 * @param cls Closure.
262 * @param message_id Set to the unique message ID that was generated for
264 * @param[in,out] data_size Initially set to the number of bytes available in @a data,
265 * should be set to the number of bytes written to data (IN/OUT).
266 * @param[out] data Where to write the body of the message to give to the method;
267 * function must copy at most @a *data_size bytes to @a data.
268 * @return #GNUNET_SYSERR on error (fatal, aborts transmission)
269 * #GNUNET_NO on success, if more data is to be transmitted later
270 * (should be used if @a *data_size was not big enough to take all the data)
271 * #GNUNET_YES if this completes the transmission (all data supplied)
273 typedef int (*GNUNET_PSYC_MasterReadyNotify)(void *cls,
280 * Handle for a pending PSYC transmission operation.
282 struct GNUNET_PSYC_MasterTransmitHandle;
286 * Send a message to call a method to all members in the PSYC channel.
288 * @param master Handle to the PSYC channel.
289 * @param increment_group_generation #GNUNET_YES if we need to increment
290 * the group generation counter after transmitting this message.
291 * @param method_name Which method should be invoked.
292 * @param env Environment containing state operations and transient variables
293 * for the message, or NULL.
294 * @param notify Function to call to obtain the arguments.
295 * @param notify_cls Closure for @a notify.
296 * @return Transmission handle, NULL on error (i.e. more than one request queued).
298 struct GNUNET_PSYC_MasterTransmitHandle *
299 GNUNET_PSYC_master_transmit (struct GNUNET_PSYC_Master *master,
300 int increment_group_generation,
301 const char *method_name,
302 const struct GNUNET_ENV_Environment *env,
303 GNUNET_PSYC_MasterReadyNotify notify,
308 * Abort transmission request to channel.
310 * @param th Handle of the request that is being aborted.
313 GNUNET_PSYC_master_transmit_cancel (struct GNUNET_PSYC_MasterTransmitHandle *th);
317 * Stop a PSYC master channel.
319 * @param master PSYC channel master to stop.
322 GNUNET_PSYC_master_stop (struct GNUNET_PSYC_Master *master);
326 * Handle for a PSYC channel slave.
328 struct GNUNET_PSYC_Slave;
332 * Join a PSYC channel.
334 * The entity joining is always the local peer. The user must immediately use
335 * the GNUNET_PSYC_slave_to_master() functions to transmit a @e join_msg to the
336 * channel; if the join request succeeds, the channel state (and @e recent
337 * method calls) will be replayed to the joining member. There is no explicit
338 * notification on failure (as the channel may simply take days to approve,
339 * and disapproval is simply being ignored).
341 * @param cfg Configuration to use.
342 * @param pub_key ECC key that identifies the channel we wish to join.
343 * @param origin Peer identity of the origin.
344 * @param method Function to invoke on messages received from the channel,
345 * typically at least contains functions for @e join and @e part.
346 * @param method_cls Closure for @a method.
347 * @param method_name Method name for the join request.
348 * @param env Environment containing transient variables for the request, or NULL.
349 * @param data_size Number of bytes in @a data.
350 * @param data Payload for the join message.
351 * @return Handle for the slave, NULL on error.
353 struct GNUNET_PSYC_Slave *
354 GNUNET_PSYC_slave_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
355 const struct GNUNET_CRYPTO_EccPublicKey *pub_key,
356 const struct GNUNET_PeerIdentity *origin,
357 GNUNET_PSYC_Method method,
359 const char *method_name,
360 const struct GNUNET_ENV_Environment *env,
366 * Part a PSYC channel.
368 * Will terminate the connection to the PSYC service. Polite clients should
369 * first explicitly send a @e part request (via GNUNET_PSYC_slave_to_master()).
371 * @param slave Slave handle.
374 GNUNET_PSYC_slave_part (struct GNUNET_PSYC_Slave *slave);
378 * Function called to provide data for a transmission to the channel
379 * master (aka the @e host of the channel).
381 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
382 * invalidates the respective transmission handle.
384 * @param cls Closure.
385 * @param[in,out] data_size Initially set to the number of bytes available in @a data,
386 * should be set to the number of bytes written to data (IN/OUT).
387 * @param[out] data Where to write the body of the message to give to the method;
388 * function must copy at most @a *data_size bytes to @a data.
389 * @return #GNUNET_SYSERR on error (fatal, aborts transmission).
390 * #GNUNET_NO on success, if more data is to be transmitted later.
391 * #GNUNET_YES if this completes the transmission (all data supplied).
393 typedef int (*GNUNET_PSYC_SlaveReadyNotify)(void *cls,
399 * Handle for a pending PSYC transmission operation.
401 struct GNUNET_PSYC_SlaveTransmitHandle;
405 * Request a message to be sent to the channel master.
407 * @param slave Slave handle.
408 * @param method_name Which (PSYC) method should be invoked (on host).
409 * @param env Environment containing transient variables for the message, or NULL.
410 * @param notify Function to call when we are allowed to transmit (to get data).
411 * @param notify_cls Closure for @a notify.
412 * @return Transmission handle, NULL on error (i.e. more than one request queued).
414 struct GNUNET_PSYC_SlaveTransmitHandle *
415 GNUNET_PSYC_slave_transmit (struct GNUNET_PSYC_Slave *slave,
416 const char *method_name,
417 const struct GNUNET_ENV_Environment *env,
418 GNUNET_PSYC_SlaveReadyNotify notify,
423 * Abort transmission request to master.
425 * @param th Handle of the request that is being aborted.
428 GNUNET_PSYC_slave_transmit_cancel (struct GNUNET_PSYC_SlaveTransmitHandle *th);
432 * Handle to access PSYC channel operations for both the master and slaves.
434 struct GNUNET_PSYC_Channel;
438 * Convert a channel @a master to a @e channel handle to access the @e channel APIs.
440 * @param master Channel master handle.
441 * @return Channel handle, valid for as long as @a master is valid.
443 struct GNUNET_PSYC_Channel *
444 GNUNET_PSYC_master_get_channel (struct GNUNET_PSYC_Master *master);
448 * Convert @a slave to a @e channel handle to access the @e channel APIs.
450 * @param slave Slave handle.
451 * @return Channel handle, valid for as long as @a slave is valid.
453 struct GNUNET_PSYC_Channel *
454 GNUNET_PSYC_slave_get_channel (struct GNUNET_PSYC_Slave *slave);
458 * Add a member to the channel.
460 * Note that this will NOT generate any PSYC traffic, it will merely update the
461 * local data base to modify how we react to <em>membership test</em> queries.
462 * The channel master still needs to explicitly transmit a @e join message to
463 * notify other channel members and they then also must still call this function
464 * in their respective methods handling the @e join message. This way, how @e
465 * join and @e part operations are exactly implemented is still up to the
466 * application; for example, there might be a @e part_all method to kick out
469 * Note that channel members are explicitly trusted to execute such methods
470 * correctly; not doing so correctly will result in either denying members
471 * access or offering access to channel data to non-members.
473 * @param channel Channel handle.
474 * @param member Which peer to add.
475 * @param message_id Message ID for the message that changed the membership.
478 GNUNET_PSYC_channel_member_add (struct GNUNET_PSYC_Channel *channel,
479 const struct GNUNET_PeerIdentity *member,
480 uint64_t message_id);
484 * Remove a member from the channel.
486 * Note that this will NOT generate any PSYC traffic, it will merely update the
487 * local data base to modify how we react to <em>membership test</em> queries.
488 * The channel master still needs to explicitly transmit a @e part message to
489 * notify other channel members and they then also must still call this function
490 * in their respective methods handling the @e part message. This way, how
491 * @e join and @e part operations are exactly implemented is still up to the
492 * application; for example, there might be a @e part_all message to kick out
495 * Note that channel members are explicitly trusted to perform these
496 * operations correctly; not doing so correctly will result in either
497 * denying members access or offering access to channel data to
500 * @param channel Channel handle.
501 * @param member Which peer to remove.
502 * @param message_id Message ID for the message that changed the membership.
505 GNUNET_PSYC_channel_member_remove (struct GNUNET_PSYC_Channel *channel,
506 const struct GNUNET_PeerIdentity *member,
507 uint64_t message_id);
511 * Function called to inform a member about stored state values for a channel.
513 * @param cls Closure.
514 * @param name Name of the state variable.
515 * @param value Value of the state variable.
516 * @param value_size Number of bytes in @a value.
518 typedef void (*GNUNET_PSYC_StateCallback)(void *cls,
525 * Handle to a story telling operation.
527 struct GNUNET_PSYC_Story;
531 * Request to be told the message history of the channel.
533 * Historic messages (but NOT the state at the time) will be replayed (given to
534 * the normal method handlers) if available and if access is permitted.
536 * To get the latest message, use 0 for both the start and end message ID.
538 * @param channel Which channel should be replayed?
539 * @param start_message_id Earliest interesting point in history.
540 * @param end_message_id Last (exclusive) interesting point in history.
541 * @param method Function to invoke on messages received from the story.
542 * @param method_cls Closure for @a method.
543 * @param finish_cb Function to call when the requested story has been fully
544 * told (counting message IDs might not suffice, as some messages
545 * might be secret and thus the listener would not know the story is
546 * finished without being told explicitly); once this function
547 * has been called, the client must not call
548 * GNUNET_PSYC_channel_story_tell_cancel() anymore.
549 * @param finish_cb_cls Closure to finish_cb.
550 * @return Handle to cancel story telling operation.
552 struct GNUNET_PSYC_Story *
553 GNUNET_PSYC_channel_story_tell (struct GNUNET_PSYC_Channel *channel,
554 uint64_t start_message_id,
555 uint64_t end_message_id,
556 GNUNET_PSYC_Method method,
558 void (*finish_cb)(void *),
559 void *finish_cb_cls);
563 * Abort story telling.
565 * This function must not be called from within method handlers (as given to
566 * GNUNET_PSYC_slave_join()) of the slave.
568 * @param story Story telling operation to stop.
571 GNUNET_PSYC_channel_story_tell_cancel (struct GNUNET_PSYC_Story *story);
575 * Call the given callback on all matching values (including variables) in the
578 * The callback is invoked synchronously on all matching states (as the state is
579 * fully replicated in the library in this process; channel states should be
580 * small, large data is to be passed as streaming data to methods).
582 * A name matches if it includes the @a state_name prefix, thus requesting the
583 * empty state ("") will match all values; requesting "_a_b" will also return
584 * values stored under "_a_b_c".
586 * @param channel Channel handle.
587 * @param state_name Name of the state to query (full name
588 * might be longer, this is only the prefix that must match).
589 * @param cb Function to call on the matching state values.
590 * @param cb_cls Closure for @a cb.
591 * @return Message ID for which the state was returned (last seen
595 GNUNET_PSYC_channel_state_get_all (struct GNUNET_PSYC_Channel *channel,
596 const char *state_name,
597 GNUNET_PSYC_StateCallback cb,
602 * Obtain the current value of the best-matching value in the state
603 * (including variables).
605 * Note that variables are only valid during a #GNUNET_PSYC_Method invocation, as
606 * variables are only valid for the duration of a method invocation.
608 * If the requested variable name does not have an exact state in
609 * the state, the nearest less-specific name is matched; for example,
610 * requesting "_a_b" will match "_a" if "_a_b" does not exist.
612 * @param channel Channel handle.
613 * @param variable_name Name of the variable to query.
614 * @param[out] return_value_size Set to number of bytes in variable,
615 * needed as variables might contain binary data and
616 * might also not be 0-terminated; set to 0 on errors.
617 * @return NULL on error (no matching state or variable), pointer
618 to the respective value otherwise.
621 GNUNET_PSYC_channel_state_get (struct GNUNET_PSYC_Channel *channel,
622 const char *variable_name,
623 size_t *return_value_size);
626 #if 0 /* keep Emacsens' auto-indent happy */
633 /* ifndef GNUNET_PSYC_SERVICE_H */
635 /* end of gnunet_psyc_service.h */