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3 Copyright (C) 2012, 2013 Christian Grothoff (and other contributing authors)
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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
48 * Opaque handle for a multicast group member.
50 struct GNUNET_MULTICAST_Member;
53 * Handle for the origin of a multicast group.
55 struct GNUNET_MULTICAST_Origin;
58 enum GNUNET_MULTICAST_MessageFlags
61 * First fragment of a message.
63 GNUNET_MULTICAST_MESSAGE_FIRST_FRAGMENT = 1 << 0,
66 * Last fragment of a message.
68 GNUNET_MULTICAST_MESSAGE_LAST_FRAGMENT = 1 << 1,
71 * OR'ed flags if message is not fragmented.
73 GNUNET_MULTICAST_MESSAGE_NOT_FRAGMENTED
74 = GNUNET_MULTICAST_MESSAGE_FIRST_FRAGMENT
75 | GNUNET_MULTICAST_MESSAGE_LAST_FRAGMENT,
78 * Historic message, used only locally when replaying messages from local
81 GNUNET_MULTICAST_MESSAGE_HISTORIC = 1 << 30
86 GNUNET_NETWORK_STRUCT_BEGIN
89 * Header of a multicast message fragment.
91 * This format is public as the replay mechanism must replay message fragments using the
92 * same format. This is needed as we want to integrity-check message fragments within
93 * the multicast layer to avoid multicasting mal-formed messages.
95 struct GNUNET_MULTICAST_MessageHeader
99 * Header for all multicast message fragments from the origin.
101 struct GNUNET_MessageHeader header;
104 * Number of hops this message fragment has taken since the origin.
106 * Helpful to determine shortest paths to the origin among honest peers for
107 * unicast requests from members. Updated at each hop and thus not signed and
110 uint32_t hop_counter GNUNET_PACKED;
113 * ECC signature of the message fragment.
115 * Signature must match the public key of the multicast group.
117 struct GNUNET_CRYPTO_EddsaSignature signature;
120 * Purpose for the signature and size of the signed data.
122 struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
125 * Number of the message fragment, monotonically increasing starting from 1.
127 uint64_t fragment_id GNUNET_PACKED;
130 * Byte offset of this @e fragment of the @e message.
132 uint64_t fragment_offset GNUNET_PACKED;
135 * Number of the message this fragment belongs to.
137 * Set in GNUNET_MULTICAST_origin_to_all().
139 uint64_t message_id GNUNET_PACKED;
142 * Counter that monotonically increases whenever a member parts the group.
144 * Set in GNUNET_MULTICAST_origin_to_all().
146 * It has significance in case of replay requests: when a member has missed
147 * messages and gets a replay request: in this case if the @a group_generation
148 * is still the same before and after the missed messages, it means that no
149 * @e join or @e part operations happened during the missed messages.
151 uint64_t group_generation GNUNET_PACKED;
154 * Flags for this message fragment.
156 * @see enum GNUNET_MULTICAST_MessageFlags
158 uint32_t flags GNUNET_PACKED;
160 /* Followed by message body. */
165 * Header of a request from a member to the origin.
167 struct GNUNET_MULTICAST_RequestHeader
170 * Header for all requests from a member to the origin.
172 struct GNUNET_MessageHeader header;
175 * Public key of the sending member.
177 struct GNUNET_CRYPTO_EcdsaPublicKey member_key;
180 * ECC signature of the request fragment.
182 * Signature must match the public key of the multicast group.
184 struct GNUNET_CRYPTO_EcdsaSignature signature;
187 * Purpose for the signature and size of the signed data.
189 struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
192 * Number of the request fragment.
193 * Monotonically increasing from 1.
195 uint64_t fragment_id GNUNET_PACKED;
198 * Byte offset of this @e fragment of the @e request.
200 uint64_t fragment_offset GNUNET_PACKED;
203 * Number of the request this fragment belongs to.
205 * Set in GNUNET_MULTICAST_origin_to_all().
207 uint64_t request_id GNUNET_PACKED;
210 * Flags for this request.
212 enum GNUNET_MULTICAST_MessageFlags flags GNUNET_PACKED;
214 /* Followed by request body. */
217 GNUNET_NETWORK_STRUCT_END
221 * Maximum size of a multicast message fragment.
223 #define GNUNET_MULTICAST_FRAGMENT_MAX_SIZE 63 * 1024
225 #define GNUNET_MULTICAST_FRAGMENT_MAX_PAYLOAD \
226 GNUNET_MULTICAST_FRAGMENT_MAX_SIZE \
227 - sizeof (struct GNUNET_MULTICAST_MessageHeader)
231 * Handle that identifies a join request.
233 * Used to match calls to #GNUNET_MULTICAST_JoinRequestCallback to the
234 * corresponding calls to #GNUNET_MULTICAST_join_decision().
236 struct GNUNET_MULTICAST_JoinHandle;
240 * Function to call with the decision made for a join request.
242 * Must be called once and only once in response to an invocation of the
243 * #GNUNET_MULTICAST_JoinRequestCallback.
246 * Join request handle.
248 * #GNUNET_YES if the join is approved,
249 * #GNUNET_NO if it is disapproved,
250 * #GNUNET_SYSERR if we cannot answer the request.
252 * Number of relays given.
254 * Array of suggested peers that might be useful relays to use
255 * when joining the multicast group (essentially a list of peers that
256 * are already part of the multicast group and might thus be willing
257 * to help with routing). If empty, only this local peer (which must
258 * be the multicast origin) is a good candidate for building the
259 * multicast tree. Note that it is unnecessary to specify our own
260 * peer identity in this array.
262 * Message to send in response to the joining peer;
263 * can also be used to redirect the peer to a different group at the
264 * application layer; this response is to be transmitted to the
265 * peer that issued the request even if admission is denied.
267 struct GNUNET_MULTICAST_ReplayHandle *
268 GNUNET_MULTICAST_join_decision (struct GNUNET_MULTICAST_JoinHandle *jh,
270 uint16_t relay_count,
271 const struct GNUNET_PeerIdentity *relays,
272 const struct GNUNET_MessageHeader *join_resp);
276 * Method called whenever another peer wants to join the multicast group.
278 * Implementations of this function must call GNUNET_MULTICAST_join_decision()
284 * Public key of the member requesting join.
286 * Application-dependent join message from the new member.
288 * Join handle to pass to GNUNET_MULTICAST_join_decison().
291 (*GNUNET_MULTICAST_JoinRequestCallback) (void *cls,
292 const struct GNUNET_CRYPTO_EcdsaPublicKey *member_key,
293 const struct GNUNET_MessageHeader *join_msg,
294 struct GNUNET_MULTICAST_JoinHandle *jh);
298 * Method called to inform about the decision in response to a join request.
300 * If @a is_admitted is not #GNUNET_YES, then the multicast service disconnects
301 * the client and the multicast member handle returned by
302 * GNUNET_MULTICAST_member_join() is invalidated.
307 * #GNUNET_YES or #GNUNET_NO or #GNUNET_SYSERR
309 * The peer we are connected to and the join decision is from.
311 * Number of peers in the @a relays array.
313 * Peer identities of members of the group, which serve as relays
314 * and can be used to join the group at. If empty, only the origin can
315 * be used to connect to the group.
317 * Application-dependent join message from the origin.
320 (*GNUNET_MULTICAST_JoinDecisionCallback) (void *cls,
322 const struct GNUNET_PeerIdentity *peer,
323 uint16_t relay_count,
324 const struct GNUNET_PeerIdentity *relays,
325 const struct GNUNET_MessageHeader *join_msg);
329 * Function called whenever a group member has transmitted a request
330 * to the origin (other than joining or leaving).
332 * FIXME: need to distinguish between origin cancelling a message (some fragments
333 * were sent, then the rest 'discarded') and the case where we got disconnected;
334 * right now, both would mean 'msg' is NULL, but they could be quite different...
335 * So the semantics from the receiver side of
336 * GNUNET_MULTICAST_member_to_origin_cancel() are not clear here. Maybe we
337 * should do something with the flags in this case?
340 * Closure (set from GNUNET_MULTICAST_origin_start).
342 * Identity of the sender.
344 * Request to the origin.
346 * Flags for the request.
349 (*GNUNET_MULTICAST_RequestCallback) (void *cls,
350 const struct GNUNET_MULTICAST_RequestHeader *req);
354 * Function called whenever a group member is receiving a message fragment from
357 * If admission to the group is denied, this function is called once with the
358 * response of the @e origin (as given to GNUNET_MULTICAST_join_decision()) and
359 * then a second time with NULL to indicate that the connection failed for good.
361 * FIXME: need to distinguish between origin cancelling a message (some fragments
362 * were sent, then the rest 'discarded') and the case where we got disconnected;
363 * right now, both would mean 'msg' is NULL, but they could be quite different...
364 * So the semantics from the receiver side of
365 * GNUNET_MULTICAST_origin_to_all_cancel() are not clear here.
368 * Closure (set from GNUNET_MULTICAST_member_join())
370 * Message from the origin, NULL if the origin shut down
371 * (or we were kicked out, and we should thus call
372 * GNUNET_MULTICAST_member_part() next)
375 (*GNUNET_MULTICAST_MessageCallback) (void *cls,
376 const struct GNUNET_MULTICAST_MessageHeader *msg);
380 * Opaque handle to a replay request from the multicast service.
382 struct GNUNET_MULTICAST_ReplayHandle;
386 * Functions with this signature are called whenever the multicast service needs
387 * a message fragment to be replayed by fragment_id.
389 * Implementations of this function MUST call GNUNET_MULTICAST_replay() ONCE
390 * (with a message or an error); however, if the origin is destroyed or the
391 * group is left, the replay handle must no longer be used.
394 * Closure (set from GNUNET_MULTICAST_origin_start()
395 * or GNUNET_MULTICAST_member_join()).
397 * The member requesting replay.
399 * Which message fragment should be replayed.
401 * Flags for the replay.
403 * Handle to pass to message transmit function.
406 (*GNUNET_MULTICAST_ReplayFragmentCallback) (void *cls,
407 const struct GNUNET_CRYPTO_EcdsaPublicKey *member_key,
408 uint64_t fragment_id,
410 struct GNUNET_MULTICAST_ReplayHandle *rh);
413 * Functions with this signature are called whenever the multicast service needs
414 * a message fragment to be replayed by message_id and fragment_offset.
416 * Implementations of this function MUST call GNUNET_MULTICAST_replay() ONCE
417 * (with a message or an error); however, if the origin is destroyed or the
418 * group is left, the replay handle must no longer be used.
421 * Closure (set from GNUNET_MULTICAST_origin_start()
422 * or GNUNET_MULTICAST_member_join()).
424 * The member requesting replay.
426 * Which message should be replayed.
427 * @param fragment_offset
428 * Offset of the fragment within of @a message_id to be replayed.
430 * Flags for the replay.
432 * Handle to pass to message transmit function.
435 (*GNUNET_MULTICAST_ReplayMessageCallback) (void *cls,
436 const struct GNUNET_CRYPTO_EcdsaPublicKey *member_key,
438 uint64_t fragment_offset,
440 struct GNUNET_MULTICAST_ReplayHandle *rh);
444 * Possible error codes during replay.
446 enum GNUNET_MULTICAST_ReplayErrorCode
450 * Everything is fine.
452 GNUNET_MULTICAST_REC_OK = 0,
455 * Message fragment not found in the message store.
457 * Either discarded if it is too old, or not arrived yet if this member has
458 * missed some messages.
460 GNUNET_MULTICAST_REC_NOT_FOUND = 1,
463 * Fragment ID counter was larger than the highest counter this
464 * replay function has ever encountered; thus it is likely the
465 * origin never sent it and we're at the HEAD of the multicast
466 * stream as far as this node is concerned.
470 GNUNET_MULTICAST_REC_PAST_HEAD = 2,
473 * Access is denied to the requested fragment, membership test did not pass.
475 GNUNET_MULTICAST_REC_ACCESS_DENIED = 3,
478 * Internal error (i.e. database error). Try some other peer.
480 GNUNET_MULTICAST_REC_INTERNAL_ERROR = 4
486 * Replay a message fragment for the multicast group.
489 * Replay handle identifying which replay operation was requested.
491 * Replayed message fragment, NULL if not found / an error occurred.
493 * Error code. See enum GNUNET_MULTICAST_ReplayErrorCode
494 * If not #GNUNET_MULTICAST_REC_OK, the replay handle is invalidated.
497 GNUNET_MULTICAST_replay_response (struct GNUNET_MULTICAST_ReplayHandle *rh,
498 const struct GNUNET_MessageHeader *msg,
499 enum GNUNET_MULTICAST_ReplayErrorCode ec);
503 * Indicate the end of the replay session.
505 * Invalidates the replay handle.
507 * @param rh Replay session to end.
510 GNUNET_MULTICAST_replay_response_end (struct GNUNET_MULTICAST_ReplayHandle *rh);
514 * Function called to provide data for a transmission for a replay.
516 * @see GNUNET_MULTICAST_replay2()
519 (*GNUNET_MULTICAST_ReplayTransmitNotify) (void *cls,
525 * Replay a message for the multicast group.
528 * Replay handle identifying which replay operation was requested.
530 * Function to call to get the message.
532 * Closure for @a notify.
535 GNUNET_MULTICAST_replay_response2 (struct GNUNET_MULTICAST_ReplayHandle *rh,
536 GNUNET_MULTICAST_ReplayTransmitNotify notify,
541 * Start a multicast group.
543 * Will advertise the origin in the P2P overlay network under the respective
544 * public key so that other peer can find this peer to join it. Peers that
545 * issue GNUNET_MULTICAST_member_join() can then transmit a join request to
546 * either an existing group member or to the origin. If the joining is
547 * approved, the member is cleared for @e replay and will begin to receive
548 * messages transmitted to the group. If joining is disapproved, the failed
549 * candidate will be given a response. Members in the group can send messages
550 * to the origin (one at a time).
553 * Configuration to use.
555 * ECC key that will be used to sign messages for this
556 * multicast session; public key is used to identify the multicast group;
557 * @param max_fragment_id
558 * Maximum fragment ID already sent to the group.
560 * @param join_request_cb
561 * Function called to approve / disapprove joining of a peer.
562 * @param replay_frag_cb
563 * Function that can be called to replay a message fragment.
564 * @param replay_msg_cb
565 * Function that can be called to replay a message.
567 * Function called with message fragments from group members.
569 * Function called with the message fragments sent to the
570 * network by GNUNET_MULTICAST_origin_to_all(). These message fragments
571 * should be stored for answering replay requests later.
573 * Closure for the various callbacks that follow.
575 * @return Handle for the origin, NULL on error.
577 struct GNUNET_MULTICAST_Origin *
578 GNUNET_MULTICAST_origin_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
579 const struct GNUNET_CRYPTO_EddsaPrivateKey *priv_key,
580 uint64_t max_fragment_id,
581 GNUNET_MULTICAST_JoinRequestCallback join_request_cb,
582 GNUNET_MULTICAST_ReplayFragmentCallback replay_frag_cb,
583 GNUNET_MULTICAST_ReplayMessageCallback replay_msg_cb,
584 GNUNET_MULTICAST_RequestCallback request_cb,
585 GNUNET_MULTICAST_MessageCallback message_cb,
589 * Function called to provide data for a transmission from the origin to all
592 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
593 * invalidates the respective transmission handle.
597 * @param[in,out] data_size
598 * Initially set to the number of bytes available in
599 * @a data, should be set to the number of bytes written to data.
601 * Where to write the body of the message to give to the
602 * method. The function must copy at most @a data_size bytes to @a data.
604 * @return #GNUNET_SYSERR on error (fatal, aborts transmission)
605 * #GNUNET_NO on success, if more data is to be transmitted later.
606 * Should be used if @a data_size was not big enough to take all the
607 * data. If 0 is returned in @a data_size the transmission is paused,
608 * and can be resumed with GNUNET_MULTICAST_origin_to_all_resume().
609 * #GNUNET_YES if this completes the transmission (all data supplied)
612 (*GNUNET_MULTICAST_OriginTransmitNotify) (void *cls,
618 * Handle for a request to send a message to all multicast group members
621 struct GNUNET_MULTICAST_OriginTransmitHandle;
625 * Send a message to the multicast group.
628 * Handle to the multicast group.
630 * Application layer ID for the message. Opaque to multicast.
631 * @param group_generation
632 * Group generation of the message. Documented in
633 * struct GNUNET_MULTICAST_MessageHeader.
635 * Function to call to get the message.
637 * Closure for @a notify.
639 * @return NULL on error (i.e. request already pending).
641 struct GNUNET_MULTICAST_OriginTransmitHandle *
642 GNUNET_MULTICAST_origin_to_all (struct GNUNET_MULTICAST_Origin *origin,
644 uint64_t group_generation,
645 GNUNET_MULTICAST_OriginTransmitNotify notify,
651 * Resume message transmission to multicast group.
653 * @param th Transmission to cancel.
656 GNUNET_MULTICAST_origin_to_all_resume (struct GNUNET_MULTICAST_OriginTransmitHandle *th);
660 * Cancel request for message transmission to multicast group.
662 * @param th Transmission to cancel.
665 GNUNET_MULTICAST_origin_to_all_cancel (struct GNUNET_MULTICAST_OriginTransmitHandle *th);
669 * Stop a multicast group.
671 * @param origin Multicast group to stop.
674 GNUNET_MULTICAST_origin_stop (struct GNUNET_MULTICAST_Origin *origin,
675 GNUNET_ContinuationCallback stop_cb,
680 * Join a multicast group.
682 * The entity joining is always the local peer. Further information about the
683 * candidate can be provided in @a join_msg. If the join fails, the
684 * @a message_cb is invoked with a (failure) response and then with NULL. If
685 * the join succeeds, outstanding (state) messages and ongoing multicast
686 * messages will be given to the @a message_cb until the member decides to part
687 * the group. The @a mem_test_cb and @a replay_cb functions may be called at
688 * anytime by the multicast service to support relaying messages to other
689 * members of the group.
692 * Configuration to use.
694 * ECC public key that identifies the group to join.
696 * ECC key that identifies the member
697 * and used to sign requests sent to the origin.
699 * Peer ID of the origin to send unicast requsets to. If NULL,
700 * unicast requests are sent back via multiple hops on the reverse path
701 * of multicast messages.
703 * Number of peers in the @a relays array.
705 * Peer identities of members of the group, which serve as relays
706 * and can be used to join the group at. and send the @a join_request to.
707 * If empty, the @a join_request is sent directly to the @a origin.
709 * Application-dependent join message to be passed to the peer @a origin.
710 * @param join_request_cb
711 * Function called to approve / disapprove joining of a peer.
712 * @param join_decision_cb
713 * Function called to inform about the join decision.
714 * @param replay_frag_cb
715 * Function that can be called to replay message fragments
716 * this peer already knows from this group. NULL if this
717 * client is unable to support replay.
718 * @param replay_msg_cb
719 * Function that can be called to replay message fragments
720 * this peer already knows from this group. NULL if this
721 * client is unable to support replay.
723 * Function to be called for all message fragments we
724 * receive from the group, excluding those our @a replay_cb
727 * Closure for callbacks.
729 * @return Handle for the member, NULL on error.
731 struct GNUNET_MULTICAST_Member *
732 GNUNET_MULTICAST_member_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
733 const struct GNUNET_CRYPTO_EddsaPublicKey *group_key,
734 const struct GNUNET_CRYPTO_EcdsaPrivateKey *member_key,
735 const struct GNUNET_PeerIdentity *origin,
736 uint16_t relay_count,
737 const struct GNUNET_PeerIdentity *relays,
738 const struct GNUNET_MessageHeader *join_request,
739 GNUNET_MULTICAST_JoinRequestCallback join_request_cb,
740 GNUNET_MULTICAST_JoinDecisionCallback join_decision_cb,
741 GNUNET_MULTICAST_ReplayFragmentCallback replay_frag_cb,
742 GNUNET_MULTICAST_ReplayMessageCallback replay_msg_cb,
743 GNUNET_MULTICAST_MessageCallback message_cb,
747 * Handle for a replay request.
749 struct GNUNET_MULTICAST_MemberReplayHandle;
753 * Request a fragment to be replayed by fragment ID.
755 * Useful if messages below the @e max_known_fragment_id given when joining are
756 * needed and not known to the client.
761 * ID of a message fragment that this client would like to see replayed.
763 * Additional flags for the replay request.
764 * It is used and defined by GNUNET_MULTICAST_ReplayFragmentCallback
766 * @return Replay request handle, NULL on error.
768 struct GNUNET_MULTICAST_MemberReplayHandle *
769 GNUNET_MULTICAST_member_replay_fragment (struct GNUNET_MULTICAST_Member *member,
770 uint64_t fragment_id,
775 * Request a message fr to be replayed.
777 * Useful if messages below the @e max_known_fragment_id given when joining are
778 * needed and not known to the client.
783 * ID of the message this client would like to see replayed.
784 * @param fragment_offset
785 * Offset of the fragment within the message to replay.
787 * Additional flags for the replay request.
788 * It is used & defined by GNUNET_MULTICAST_ReplayMessageCallback
790 * @return Replay request handle, NULL on error.
792 struct GNUNET_MULTICAST_MemberReplayHandle *
793 GNUNET_MULTICAST_member_replay_message (struct GNUNET_MULTICAST_Member *member,
795 uint64_t fragment_offset,
800 * Cancel a replay request.
806 GNUNET_MULTICAST_member_replay_cancel (struct GNUNET_MULTICAST_MemberReplayHandle *rh);
810 * Part a multicast group.
812 * Disconnects from all group members and invalidates the @a member handle.
814 * An application-dependent part message can be transmitted beforehand using
815 * #GNUNET_MULTICAST_member_to_origin())
821 GNUNET_MULTICAST_member_part (struct GNUNET_MULTICAST_Member *member,
822 GNUNET_ContinuationCallback part_cb,
827 * Function called to provide data for a transmission from a member to the origin.
829 * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO)
830 * invalidates the respective transmission handle.
834 * @param[in,out] data_size
835 * Initially set to the number of bytes available in
836 * @a data, should be set to the number of bytes written to data.
838 * Where to write the body of the message to give to the
839 * method. The function must copy at most @a data_size bytes to @a data.
841 * @return #GNUNET_SYSERR on error (fatal, aborts transmission)
842 * #GNUNET_NO on success, if more data is to be transmitted later.
843 * Should be used if @a data_size was not big enough to take all the
844 * data. If 0 is returned in @a data_size the transmission is paused,
845 * and can be resumed with GNUNET_MULTICAST_member_to_origin_resume().
846 * #GNUNET_YES if this completes the transmission (all data supplied)
849 (*GNUNET_MULTICAST_MemberTransmitNotify) (void *cls,
855 * Handle for a message to be delivered from a member to the origin.
857 struct GNUNET_MULTICAST_MemberTransmitHandle;
861 * Send a message to the origin of the multicast group.
866 * Application layer ID for the request. Opaque to multicast.
868 * Callback to call to get the message.
870 * Closure for @a notify.
872 * @return Handle to cancel request, NULL on error (i.e. request already pending).
874 struct GNUNET_MULTICAST_MemberTransmitHandle *
875 GNUNET_MULTICAST_member_to_origin (struct GNUNET_MULTICAST_Member *member,
877 GNUNET_MULTICAST_MemberTransmitNotify notify,
882 * Resume message transmission to origin.
885 * Transmission to cancel.
888 GNUNET_MULTICAST_member_to_origin_resume (struct GNUNET_MULTICAST_MemberTransmitHandle *th);
892 * Cancel request for message transmission to origin.
895 * Transmission to cancel.
898 GNUNET_MULTICAST_member_to_origin_cancel (struct GNUNET_MULTICAST_MemberTransmitHandle *th);
901 #if 0 /* keep Emacsens' auto-indent happy */
908 /* ifndef GNUNET_MULTICAST_SERVICE_H */
910 /* end of gnunet_multicast_service.h */