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22 * @file include/gnunet_multicast_service.h
23 * @brief multicast service; establish tunnels to distant peers
24 * @author Christian Grothoff
25 * @author Gabor X Toth
28 #ifndef GNUNET_MULTICAST_SERVICE_H
29 #define GNUNET_MULTICAST_SERVICE_H
34 #if 0 /* keep Emacsens' auto-indent happy */
39 #include "gnunet_util_lib.h"
40 #include "gnunet_transport_service.h"
43 * Version number of GNUnet-multicast API.
45 #define GNUNET_MULTICAST_VERSION 0x00000000
49 * Opaque handle for a multicast group member.
51 struct GNUNET_MULTICAST_Member;
54 * Handle for the origin of a multicast group.
56 struct GNUNET_MULTICAST_Origin;
59 enum GNUNET_MULTICAST_MessageFlags
62 * First fragment of a message.
64 GNUNET_MULTICAST_MESSAGE_FIRST_FRAGMENT = 1 << 0,
67 * Last fragment of a message.
69 GNUNET_MULTICAST_MESSAGE_LAST_FRAGMENT = 1 << 1,
72 * OR'ed flags if message is not fragmented.
74 GNUNET_MULTICAST_MESSAGE_NOT_FRAGMENTED
75 = GNUNET_MULTICAST_MESSAGE_FIRST_FRAGMENT
76 | GNUNET_MULTICAST_MESSAGE_LAST_FRAGMENT
80 GNUNET_NETWORK_STRUCT_BEGIN
83 * Header of a multicast message fragment.
85 * This format is public as the replay mechanism must replay message fragments using the
86 * same format. This is needed as we want to integrity-check message fragments within
87 * the multicast layer to avoid multicasting mal-formed messages.
89 struct GNUNET_MULTICAST_MessageHeader
93 * Header for all multicast message fragments from the origin.
95 struct GNUNET_MessageHeader header;
98 * Number of hops this message fragment has taken since the origin.
100 * Helpful to determine shortest paths to the origin among honest peers for
101 * unicast requests from members. Updated at each hop and thus not signed and
104 uint32_t hop_counter GNUNET_PACKED;
107 * ECC signature of the message fragment.
109 * Signature must match the public key of the multicast group.
111 struct GNUNET_CRYPTO_EccSignature signature;
114 * Purpose for the signature and size of the signed data.
116 struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
119 * Number of the message fragment, monotonically increasing.
121 uint64_t fragment_id GNUNET_PACKED;
124 * Byte offset of this @e fragment of the @e message.
126 uint64_t fragment_offset GNUNET_PACKED;
129 * Number of the message this fragment belongs to.
131 * Set in GNUNET_MULTICAST_origin_to_all().
133 uint64_t message_id GNUNET_PACKED;
136 * Counter that monotonically increases whenever a member parts the group.
138 * Set in GNUNET_MULTICAST_origin_to_all().
140 * It has significance in case of replay requests: when a member has missed
141 * messages and gets a replay request: in this case if the @a group_generation
142 * is still the same before and after the missed messages, it means that no
143 * @e join or @e part operations happened during the missed messages.
145 uint64_t group_generation GNUNET_PACKED;
148 * Flags for this message fragment.
150 uint32_t flags GNUNET_PACKED;
152 /* Followed by message body. */
155 GNUNET_NETWORK_STRUCT_END
159 * Handle that identifies a join request.
161 * Used to match calls to #GNUNET_MULTICAST_JoinCallback to the
162 * corresponding calls to #GNUNET_MULTICAST_join_decision().
164 struct GNUNET_MULTICAST_JoinHandle;
168 * Function to call with the decision made for a join request.
170 * Must be called once and only once in response to an invocation of the
171 * #GNUNET_MULTICAST_JoinCallback.
173 * @param jh Join request handle.
174 * @param is_admitted #GNUNET_YES if joining is approved,
175 * #GNUNET_NO if it is disapproved
176 * @param relay_count Number of relays given.
177 * @param relays Array of suggested peers that might be useful relays to use
178 * when joining the multicast group (essentially a list of peers that
179 * are already part of the multicast group and might thus be willing
180 * to help with routing). If empty, only this local peer (which must
181 * be the multicast origin) is a good candidate for building the
182 * multicast tree. Note that it is unnecessary to specify our own
183 * peer identity in this array.
184 * @param join_response Message to send in response to the joining peer;
185 * can also be used to redirect the peer to a different group at the
186 * application layer; this response is to be transmitted to the
187 * peer that issued the request even if admission is denied.
189 struct GNUNET_MULTICAST_ReplayHandle *
190 GNUNET_MULTICAST_join_decision (struct GNUNET_MULTICAST_JoinHandle *jh,
192 unsigned int relay_count,
193 const struct GNUNET_PeerIdentity *relays,
194 const struct GNUNET_MessageHeader *join_response);
198 * Method called whenever another peer wants to join the multicast group.
200 * Implementations of this function must call GNUNET_MULTICAST_join_decision()
203 * @param cls Closure.
204 * @param peer Identity of the member that wants to join.
205 * @param join_req Application-dependent join message from the new member
206 * (might, for example, contain a user,
207 * bind user identity/pseudonym to peer identity, application-level
208 * message to origin, etc.).
209 * @param jh Join handle to pass to GNUNET_MULTICAST_join_decison().
212 (*GNUNET_MULTICAST_JoinCallback) (void *cls,
213 const struct GNUNET_CRYPTO_EccPublicSignKey *member_key,
214 const struct GNUNET_MessageHeader *join_req,
215 struct GNUNET_MULTICAST_JoinHandle *jh);
219 * Handle to pass back for the answer of a membership test.
221 struct GNUNET_MULTICAST_MembershipTestHandle;
225 * Call informing multicast about the decision taken for a membership test.
227 * @param mth Handle that was given for the query.
228 * @param result #GNUNET_YES if peer was a member, #GNUNET_NO if peer was not a member,
229 * #GNUNET_SYSERR if we cannot answer the membership test.
232 GNUNET_MULTICAST_membership_test_result (struct GNUNET_MULTICAST_MembershipTestHandle *mth,
237 * Method called to test if a member was in the group at a particular time.
239 * It is called when a replay request is received to determine if the requested
240 * message can be replayed.
242 * @param cls Closure.
243 * @param member_key Identity of the member that we want to test.
244 * @param message_id Message ID for which to perform the test.
245 * @param group_generation Group generation of the message. It has relevance if
246 * the message consists of multiple fragments with different group
248 * @param mth Handle to give to GNUNET_MULTICAST_membership_test_answer().
251 (*GNUNET_MULTICAST_MembershipTestCallback) (void *cls,
252 const struct GNUNET_CRYPTO_EccPublicSignKey *member_key,
254 uint64_t group_generation,
255 struct GNUNET_MULTICAST_MembershipTestHandle *mth);
259 * Function called whenever a group member has transmitted a request
260 * to the origin (other than joining or leaving).
262 * FIXME: need to distinguish between origin cancelling a message (some fragments
263 * were sent, then the rest 'discarded') and the case where we got disconnected;
264 * right now, both would mean 'msg' is NULL, but they could be quite different...
265 * So the semantics from the receiver side of
266 * GNUNET_MULTICAST_member_to_origin_cancel() are not clear here. Maybe we
267 * should do something with the flags in this case?
269 * @param cls Closure (set from GNUNET_MULTICAST_origin_start).
270 * @param sender Identity of the sender.
271 * @param req Request to the origin.
272 * @param flags Flags for the request.
275 (*GNUNET_MULTICAST_RequestCallback) (void *cls,
276 const struct GNUNET_CRYPTO_EccPublicSignKey *member_key,
277 const struct GNUNET_MessageHeader *req,
278 enum GNUNET_MULTICAST_MessageFlags flags);
282 * Function called whenever a group member is receiving a message fragment from
285 * If admission to the group is denied, this function is called once with the
286 * response of the @e origin (as given to GNUNET_MULTICAST_join_decision()) and
287 * then a second time with NULL to indicate that the connection failed for good.
289 * FIXME: need to distinguish between origin cancelling a message (some fragments
290 * were sent, then the rest 'discarded') and the case where we got disconnected;
291 * right now, both would mean 'msg' is NULL, but they could be quite different...
292 * So the semantics from the receiver side of
293 * GNUNET_MULTICAST_origin_to_all_cancel() are not clear here.
295 * @param cls Closure (set from GNUNET_MULTICAST_member_join())
296 * @param msg Message from the origin, NULL if the origin shut down
297 * (or we were kicked out, and we should thus call
298 * GNUNET_MULTICAST_member_part() next)
301 (*GNUNET_MULTICAST_MessageCallback) (void *cls,
302 const struct GNUNET_MessageHeader *msg);
306 * Function called with the result of an asynchronous operation.
308 * @see GNUNET_MULTICAST_replay_fragment()
310 * @param result Result of the operation.
313 (*GNUNET_MULTICAST_ResultCallback) (void *cls,
318 * Opaque handle to a replay request from the multicast service.
320 struct GNUNET_MULTICAST_ReplayHandle;
324 * Functions with this signature are called whenever the multicast service needs
325 * a message fragment to be replayed by fragment_id.
327 * Implementations of this function MUST call GNUNET_MULTICAST_replay() ONCE
328 * (with a message or an error); however, if the origin is destroyed or the
329 * group is left, the replay handle must no longer be used.
331 * @param cls Closure (set from GNUNET_MULTICAST_origin_start()
332 * or GNUNET_MULTICAST_member_join()).
333 * @param member_key The member requesting replay.
334 * @param fragment_id Which message fragment should be replayed.
335 * @param flags Flags for the replay.
336 * @param rh Handle to pass to message transmit function.
339 (*GNUNET_MULTICAST_ReplayFragmentCallback) (void *cls,
340 const struct GNUNET_CRYPTO_EccPublicSignKey *member_key,
341 uint64_t fragment_id,
343 struct GNUNET_MULTICAST_ReplayHandle *rh);
346 * Functions with this signature are called whenever the multicast service needs
347 * a message fragment to be replayed by message_id and fragment_offset.
349 * Implementations of this function MUST call GNUNET_MULTICAST_replay() ONCE
350 * (with a message or an error); however, if the origin is destroyed or the
351 * group is left, the replay handle must no longer be used.
353 * @param cls Closure (set from GNUNET_MULTICAST_origin_start()
354 * or GNUNET_MULTICAST_member_join()).
355 * @param member_key The member requesting replay.
356 * @param message_id Which message should be replayed.
357 * @param fragment_offset Offset of the fragment within of @a message_id to be replayed.
358 * @param flags Flags for the replay.
359 * @param rh Handle to pass to message transmit function.
362 (*GNUNET_MULTICAST_ReplayMessageCallback) (void *cls,
363 const struct GNUNET_CRYPTO_EccPublicSignKey *member_key,
365 uint64_t fragment_offset,
367 struct GNUNET_MULTICAST_ReplayHandle *rh);
371 * Possible error codes during replay.
373 enum GNUNET_MULTICAST_ReplayErrorCode
377 * Everything is fine.
379 GNUNET_MULTICAST_REC_OK = 0,
382 * Message fragment not found in the message store.
384 * Either discarded if it is too old, or not arrived yet if this member has
385 * missed some messages.
387 GNUNET_MULTICAST_REC_NOT_FOUND = 1,
390 * Fragment ID counter was larger than the highest counter this
391 * replay function has ever encountered; thus it is likely the
392 * origin never sent it and we're at the HEAD of the multicast
393 * stream as far as this node is concerned.
397 GNUNET_MULTICAST_REC_PAST_HEAD = 2,
400 * Access is denied to the requested fragment, membership test did not pass.
402 GNUNET_MULTICAST_REC_ACCESS_DENIED = 3,
405 * Internal error (i.e. database error). Try some other peer.
407 GNUNET_MULTICAST_REC_INTERNAL_ERROR = 4
413 * Replay a message fragment for the multicast group.
415 * @param rh Replay handle identifying which replay operation was requested.
416 * @param msg Replayed message fragment, NULL if unknown/error.
417 * @param ec Error code.
420 GNUNET_MULTICAST_replay_response (struct GNUNET_MULTICAST_ReplayHandle *rh,
421 const struct GNUNET_MessageHeader *msg,
422 enum GNUNET_MULTICAST_ReplayErrorCode ec);
426 * Indicate the end of the replay session.
428 * Invalidates the replay handle.
430 * @param rh Replay session to end.
433 GNUNET_MULTICAST_replay_response_end (struct GNUNET_MULTICAST_ReplayHandle *rh);
437 * Function called to provide data for a transmission for a replay.
439 * @see GNUNET_MULTICAST_replay2()
442 (*GNUNET_MULTICAST_ReplayTransmitNotify) (void *cls,
448 * Replay a message for the multicast group.
450 * @param rh Replay handle identifying which replay operation was requested.
451 * @param notify Function to call to get the message.
452 * @param notify_cls Closure for @a notify.
455 GNUNET_MULTICAST_replay_response2 (struct GNUNET_MULTICAST_ReplayHandle *rh,
456 GNUNET_MULTICAST_ReplayTransmitNotify notify,
461 * Start a multicast group.
463 * Will advertise the origin in the P2P overlay network under the respective
464 * public key so that other peer can find this peer to join it. Peers that
465 * issue GNUNET_MULTICAST_member_join() can then transmit a join request to
466 * either an existing group member or to the origin. If the joining is
467 * approved, the member is cleared for @e replay and will begin to receive
468 * messages transmitted to the group. If joining is disapproved, the failed
469 * candidate will be given a response. Members in the group can send messages
470 * to the origin (one at a time).
472 * @param cfg Configuration to use.
473 * @param priv_key ECC key that will be used to sign messages for this
474 * multicast session; public key is used to identify the multicast group;
475 * @param last_fragment_id Last fragment ID to continue counting fragments from
476 * when restarting the origin. 0 for a new group.
477 * @param join_cb Function called to approve / disapprove joining of a peer.
478 * @param test_cb Function multicast can use to test group membership.
479 * @param replay_frag_cb Function that can be called to replay a message fragment.
480 * @param replay_msg_cb Function that can be called to replay a message.
481 * @param request_cb Function called with message fragments from group members.
482 * @param message_cb Function called with the message fragments sent to the
483 * network by GNUNET_MULTICAST_origin_to_all(). These message fragments
484 * should be stored for answering replay requests later.
485 * @param cls Closure for the various callbacks that follow.
486 * @return Handle for the origin, NULL on error.
488 struct GNUNET_MULTICAST_Origin *
489 GNUNET_MULTICAST_origin_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
490 const struct GNUNET_CRYPTO_EccPrivateKey *priv_key,
491 uint64_t last_fragment_id,
492 GNUNET_MULTICAST_JoinCallback join_cb,
493 GNUNET_MULTICAST_MembershipTestCallback test_cb,
494 GNUNET_MULTICAST_ReplayFragmentCallback replay_frag_cb,
495 GNUNET_MULTICAST_ReplayMessageCallback replay_msg_cb,
496 GNUNET_MULTICAST_RequestCallback request_cb,
497 GNUNET_MULTICAST_MessageCallback message_cb,
501 * Function called to provide data for a transmission from the origin to all
503 * FIXME: what if origin needs to pause transmission for a while?
506 * @param data_size number of bytes available in @a data
507 * @param data where to copy the message
508 * @return number of bytes copied to @a data? (FIXME: size_t?), or status code?
511 (*GNUNET_MULTICAST_OriginTransmitNotify) (void *cls,
517 * Handle for a request to send a message to all multicast group members
520 struct GNUNET_MULTICAST_OriginMessageHandle;
524 * Send a message to the multicast group.
526 * @param origin Handle to the multicast group.
527 * @param message_id Application layer ID for the message. Opaque to multicast.
528 * @param group_generation Group generation of the message. Documented in
529 * GNUNET_MULTICAST_MessageHeader.
530 * @param size Number of bytes to transmit.
531 * FIXME: Needed? The end of the message can be flagged with a last fragment flag.
532 * FIXME: what last fragment flag? OriginTransmitNotify is not that well documented...
533 * FIXME: size_t? If this is a total size, uint64_t might be better!
534 * FIXME: do we reserve "MAX" to indicate 'unknown'?
535 * @param notify Function to call to get the message.
536 * @param notify_cls Closure for @a notify.
537 * @return NULL on error (i.e. request already pending).
539 struct GNUNET_MULTICAST_OriginMessageHandle *
540 GNUNET_MULTICAST_origin_to_all (struct GNUNET_MULTICAST_Origin *origin,
542 uint64_t group_generation,
544 GNUNET_MULTICAST_OriginTransmitNotify notify,
549 * Cancel request for message transmission to multicast group.
551 * @param mh Request to cancel.
554 GNUNET_MULTICAST_origin_to_all_cancel (struct GNUNET_MULTICAST_OriginMessageHandle *mh);
558 * Stop a multicast group.
560 * @param origin Multicast group to stop.
563 GNUNET_MULTICAST_origin_stop (struct GNUNET_MULTICAST_Origin *origin);
567 * Join a multicast group.
569 * The entity joining is always the local peer. Further information about the
570 * candidate can be provided in the @a join_request message. If the join fails, the
571 * @a message_cb is invoked with a (failure) response and then with NULL. If
572 * the join succeeds, outstanding (state) messages and ongoing multicast
573 * messages will be given to the @a message_cb until the member decides to part
574 * the group. The @a test_cb and @a replay_cb functions may be called at
575 * anytime by the multicast service to support relaying messages to other
576 * members of the group.
578 * @param cfg Configuration to use.
579 * @param group_key ECC public key that identifies the group to join.
580 * @param member_key ECC key that identifies the member and used to sign
581 * requests sent to the origin.
582 * @param origin Peer ID of the origin to send unicast requsets to. If NULL,
583 * unicast requests are sent back via multiple hops on the reverse path
584 * of multicast messages.
585 * @param relay_count Number of peers in the @a relays array.
586 * @param relays Peer identities of members of the group, which serve as relays
587 * and can be used to join the group at. and send the @a join_request to.
588 * If empty, the @a join_request is sent directly to the @a origin.
589 * @param join_request Application-dependent join request to be passed to the peer
590 * @a relay (might, for example, contain a user, bind user
591 * identity/pseudonym to peer identity, application-level message to
593 * @param join_cb Function called to approve / disapprove joining of a peer.
594 * @param test_cb Function multicast can use to test group membership.
595 * @param replay_frag_cb Function that can be called to replay message fragments
596 * this peer already knows from this group. NULL if this
597 * client is unable to support replay.
598 * @param replay_msg_cb Function that can be called to replay message fragments
599 * this peer already knows from this group. NULL if this
600 * client is unable to support replay.
601 * @param message_cb Function to be called for all message fragments we
602 * receive from the group, excluding those our @a replay_cb
604 * @param cls Closure for callbacks.
605 * @return Handle for the member, NULL on error.
607 struct GNUNET_MULTICAST_Member *
608 GNUNET_MULTICAST_member_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
609 const struct GNUNET_CRYPTO_EccPublicSignKey *group_key,
610 const struct GNUNET_CRYPTO_EccPrivateKey *member_key,
611 const struct GNUNET_PeerIdentity *origin,
612 uint32_t relay_count,
613 const struct GNUNET_PeerIdentity *relays,
614 const struct GNUNET_MessageHeader *join_request,
615 GNUNET_MULTICAST_JoinCallback join_cb,
616 GNUNET_MULTICAST_MembershipTestCallback test_cb,
617 GNUNET_MULTICAST_ReplayFragmentCallback replay_frag_cb,
618 GNUNET_MULTICAST_ReplayMessageCallback replay_msg_cb,
619 GNUNET_MULTICAST_MessageCallback message_cb,
623 * Handle for a replay request.
625 struct GNUNET_MULTICAST_MemberReplayHandle;
629 * Request a fragment to be replayed by fragment ID.
631 * Useful if messages below the @e max_known_fragment_id given when joining are
632 * needed and not known to the client.
634 * @param member Membership handle.
635 * @param fragment_id ID of a message fragment that this client would like to
637 * @param flags Additional flags for the replay request. It is used and defined
638 * by the replay callback. FIXME: which replay callback? FIXME: use enum?
639 * FIXME: why not pass reply cb here?
640 * @return Replay request handle, NULL on error.
642 struct GNUNET_MULTICAST_MemberReplayHandle *
643 GNUNET_MULTICAST_member_replay_fragment (struct GNUNET_MULTICAST_Member *member,
644 uint64_t fragment_id,
649 * Request a message fr to be replayed.
651 * Useful if messages below the @e max_known_fragment_id given when joining are
652 * needed and not known to the client.
654 * @param member Membership handle.
655 * @param message_id ID of the message this client would like to see replayed.
656 * @param fragment_offset Offset of the fragment within the message to replay.
657 * @param flags Additional flags for the replay request. It is used & defined
658 * by the replay callback.
659 * @param result_cb Function to be called for the replayed message.
660 * @param result_cb_cls Closure for @a result_cb.
661 * @return Replay request handle, NULL on error.
663 struct GNUNET_MULTICAST_MemberReplayHandle *
664 GNUNET_MULTICAST_member_replay_message (struct GNUNET_MULTICAST_Member *member,
666 uint64_t fragment_offset,
668 GNUNET_MULTICAST_ResultCallback result_cb,
669 void *result_cb_cls);
673 * Cancel a replay request.
675 * @param rh Request to cancel.
678 GNUNET_MULTICAST_member_replay_cancel (struct GNUNET_MULTICAST_MemberReplayHandle *rh);
682 * Part a multicast group.
684 * Disconnects from all group members and invalidates the @a member handle.
686 * An application-dependent part message can be transmitted beforehand using
687 * #GNUNET_MULTICAST_member_to_origin())
689 * @param member Membership handle.
692 GNUNET_MULTICAST_member_part (struct GNUNET_MULTICAST_Member *member);
696 * Function called to provide data for a transmission from a member to the origin.
699 * @param data_size number of bytes available in @a data
700 * @param data where to copy data for transmission
701 * @return number of bytes copied to data
704 (*GNUNET_MULTICAST_MemberTransmitNotify) (void *cls,
710 * Handle for a message to be delivered from a member to the origin.
712 struct GNUNET_MULTICAST_MemberRequestHandle;
716 * Send a message to the origin of the multicast group.
718 * @param member Membership handle.
719 * @param message_id Application layer ID for the message. Opaque to multicast.
720 * @param size Number of bytes we want to send to origin.
721 * FIXME: this should probably be a uint64_t?
722 * @param notify Callback to call to get the message.
723 * @param notify_cls Closure for @a notify.
724 * @return Handle to cancel request, NULL on error (i.e. request already pending).
726 struct GNUNET_MULTICAST_MemberRequestHandle *
727 GNUNET_MULTICAST_member_to_origin (struct GNUNET_MULTICAST_Member *member,
730 GNUNET_MULTICAST_MemberTransmitNotify notify,
735 * Cancel request for message transmission to origin.
737 * @param rh Request to cancel.
740 GNUNET_MULTICAST_member_to_origin_cancel (struct GNUNET_MULTICAST_MemberRequestHandle *rh);
743 #if 0 /* keep Emacsens' auto-indent happy */
750 /* ifndef GNUNET_MULTICAST_SERVICE_H */
752 /* end of gnunet_multicast_service.h */