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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 enum GNUNET_MULTICAST_MessageFlags flags GNUNET_PACKED;
152 /* Followed by message body. */
155 GNUNET_NETWORK_STRUCT_END
157 GNUNET_NETWORK_STRUCT_BEGIN
160 * Header of a request from a member to the origin.
162 * FIXME: this struct is going to be internal.
164 struct GNUNET_MULTICAST_RequestHeader
167 * Header for all requests from a member to the origin.
169 struct GNUNET_MessageHeader header;
172 * Public key of the sending member.
174 struct GNUNET_CRYPTO_EccPublicKey member_key;
177 * ECC signature of the request fragment.
179 * Signature must match the public key of the multicast group.
181 struct GNUNET_CRYPTO_EccSignature signature;
184 * Purpose for the signature and size of the signed data.
186 struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
189 * Number of the request fragment, monotonically increasing.
191 uint64_t fragment_id GNUNET_PACKED;
194 * Byte offset of this @e fragment of the @e request.
196 uint64_t fragment_offset GNUNET_PACKED;
199 * Number of the request this fragment belongs to.
201 * Set in GNUNET_MULTICAST_origin_to_all().
203 uint64_t request_id GNUNET_PACKED;
206 * Flags for this request.
208 enum GNUNET_MULTICAST_MessageFlags flags GNUNET_PACKED;
210 /* Followed by request body. */
213 GNUNET_NETWORK_STRUCT_END
216 GNUNET_NETWORK_STRUCT_BEGIN
219 * Header of a join request sent to the origin or another member.
221 * FIXME: this struct is going to be internal.
223 struct GNUNET_MULTICAST_JoinRequest {
225 * Header for the join request.
227 struct GNUNET_MessageHeader header;
230 * ECC signature of the rest of the fields of the join request.
232 * Signature must match the public key of the joining member.
234 struct GNUNET_CRYPTO_EccSignature signature;
237 * Purpose for the signature and size of the signed data.
239 struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
242 * Public key of the target group.
244 struct GNUNET_CRYPTO_EccPublicKey group_key;
247 * Public key of the joining member.
249 struct GNUNET_CRYPTO_EccPublicKey member_key;
252 * Peer identity of the joining member.
254 struct GNUNET_PeerIdentity member_peer;
256 /* Followed by request body. */
259 GNUNET_NETWORK_STRUCT_END
263 * Handle that identifies a join request.
265 * Used to match calls to #GNUNET_MULTICAST_JoinCallback to the
266 * corresponding calls to #GNUNET_MULTICAST_join_decision().
268 struct GNUNET_MULTICAST_JoinHandle;
272 * Function to call with the decision made for a join request.
274 * Must be called once and only once in response to an invocation of the
275 * #GNUNET_MULTICAST_JoinCallback.
277 * @param jh Join request handle.
278 * @param is_admitted #GNUNET_YES if joining is approved,
279 * #GNUNET_NO if it is disapproved
280 * @param admitted_since Message ID the member is admitted since.
281 * @param relay_count Number of relays given.
282 * @param relays Array of suggested peers that might be useful relays to use
283 * when joining the multicast group (essentially a list of peers that
284 * are already part of the multicast group and might thus be willing
285 * to help with routing). If empty, only this local peer (which must
286 * be the multicast origin) is a good candidate for building the
287 * multicast tree. Note that it is unnecessary to specify our own
288 * peer identity in this array.
289 * @param join_response Message to send in response to the joining peer;
290 * can also be used to redirect the peer to a different group at the
291 * application layer; this response is to be transmitted to the
292 * peer that issued the request even if admission is denied.
295 GNUNET_MULTICAST_join_decision (struct GNUNET_MULTICAST_JoinHandle *jh,
297 uint64_t admitted_since,
298 unsigned int relay_count,
299 const struct GNUNET_PeerIdentity *relays,
300 const struct GNUNET_MessageHeader *join_response);
304 * Method called whenever another peer wants to join the multicast group.
306 * Implementations of this function must call GNUNET_MULTICAST_join_decision()
309 * @param cls Closure.
310 * @param peer Identity of the member that wants to join.
311 * @param join_req Application-dependent join message from the new member
312 * (might, for example, contain a user,
313 * bind user identity/pseudonym to peer identity, application-level
314 * message to origin, etc.).
315 * @param jh Join handle to pass to GNUNET_MULTICAST_join_decison().
318 (*GNUNET_MULTICAST_JoinCallback) (void *cls,
319 const struct GNUNET_EccPublicKey *member_key,
320 const struct GNUNET_MessageHeader *join_req,
321 struct GNUNET_MULTICAST_JoinHandle *jh);
325 * Handle to pass back for the answer of a membership test.
327 struct GNUNET_MULTICAST_MembershipTestHandle;
331 * Call informing multicast about the decision taken for a membership test.
333 * @param mth Handle that was given for the query.
334 * @param result #GNUNET_YES if peer was a member, #GNUNET_NO if peer was not a member,
335 * #GNUNET_SYSERR if we cannot answer the membership test.
338 GNUNET_MULTICAST_membership_test_result (struct GNUNET_MULTICAST_MembershipTestHandle *mth,
343 * Method called to test if a member was in the group at a particular time.
345 * It is called when a replay request is received to determine if the requested
346 * message can be replayed.
348 * @param cls Closure.
349 * @param member_key Identity of the member that we want to test.
350 * @param message_id Message ID for which to perform the test.
351 * @param group_generation Group generation of the message. It has relevance if
352 * the message consists of multiple fragments with different group
354 * @param mth Handle to give to GNUNET_MULTICAST_membership_test_answer().
357 (*GNUNET_MULTICAST_MembershipTestCallback) (void *cls,
358 const struct GNUNET_CRYPTO_EccPublicKey *member_key,
360 uint64_t group_generation,
361 struct GNUNET_MULTICAST_MembershipTestHandle *mth);
365 * Function called whenever a group member has transmitted a request
366 * to the origin (other than joining or leaving).
368 * @param cls Closure (set from GNUNET_MULTICAST_origin_start).
369 * @param sender Identity of the sender.
370 * @param req Request to the origin.
371 * @param flags Flags for the request.
374 (*GNUNET_MULTICAST_RequestCallback) (void *cls,
375 const struct GNUNET_EccPublicKey *member_key,
376 const struct GNUNET_MessageHeader *req,
377 enum GNUNET_MULTICAST_MessageFlags flags);
381 * Function called whenever a group member is receiving a message fragment from
384 * If admission to the group is denied, this function is called once with the
385 * response of the @e origin (as given to GNUNET_MULTICAST_join_decision()) and
386 * then a second time with NULL to indicate that the connection failed for good.
388 * @param cls Closure (set from GNUNET_MULTICAST_member_join())
389 * @param msg Message from the origin, NULL if the origin shut down
390 * (or we were kicked out, and we should thus call
391 * GNUNET_MULTICAST_member_part() next)
394 (*GNUNET_MULTICAST_MessageCallback) (void *cls,
395 const struct GNUNET_MessageHeader *msg);
399 * Function called with the result of an asynchronous operation.
401 * @see GNUNET_MULTICAST_replay_fragment()
403 * @param result Result of the operation.
406 (*GNUNET_MULTICAST_ResultCallback) (void *cls,
411 * Opaque handle to a replay request from the multicast service.
413 struct GNUNET_MULTICAST_ReplayHandle;
417 * Functions with this signature are called whenever the multicast service needs
418 * a message to be replayed.
420 * Implementations of this function MUST call GNUNET_MULTICAST_replay() ONCE
421 * (with a message or an error); however, if the origin is destroyed or the
422 * group is left, the replay handle must no longer be used.
424 * @param cls Closure (set from GNUNET_MULTICAST_origin_start()
425 * or GNUNET_MULTICAST_member_join()).
426 * @param member_key The member requesting replay.
427 * @param fragment_id Which message fragment should be replayed.
428 * @param flags Flags for the replay.
429 * @param rh Handle to pass to message transmit function.
432 (*GNUNET_MULTICAST_ReplayFragmentCallback) (void *cls,
433 const struct GNUNET_CRYPTO_EccPublicKey *member_key,
434 uint64_t fragment_id,
436 struct GNUNET_MULTICAST_ReplayHandle *rh);
439 * Functions with this signature are called whenever the multicast service needs
440 * a message to be replayed.
442 * Implementations of this function MUST call GNUNET_MULTICAST_replay() ONCE
443 * (with a message or an error); however, if the origin is destroyed or the
444 * group is left, the replay handle must no longer be used.
446 * @param cls Closure (set from GNUNET_MULTICAST_origin_start()
447 * or GNUNET_MULTICAST_member_join()).
448 * @param member_key The member requesting replay.
449 * @param message_id Which message should be replayed.
450 * @param fragment_offset Offset of the fragment within of @a message_id to be replayed.
451 * @param flags Flags for the replay.
452 * @param rh Handle to pass to message transmit function.
455 (*GNUNET_MULTICAST_ReplayMessageCallback) (void *cls,
456 const struct GNUNET_CRYPTO_EccPublicKey *member_key,
458 uint64_t fragment_offset,
460 struct GNUNET_MULTICAST_ReplayHandle *rh);
464 * Possible error codes during replay.
466 enum GNUNET_MULTICAST_ReplayErrorCode
470 * Everything is fine.
472 GNUNET_MULTICAST_REC_OK = 0,
475 * Message fragment not found in the message store.
477 * Either discarded if it is too old, or not arrived yet if this member has
478 * missed some messages.
480 GNUNET_MULTICAST_REC_NOT_FOUND = 1,
483 * Fragment ID counter was larger than the highest counter this
484 * replay function has ever encountered; thus it is likely the
485 * origin never sent it and we're at the HEAD of the multicast
486 * stream as far as this node is concerned.
490 GNUNET_MULTICAST_REC_PAST_HEAD = 2,
493 * Access is denied to the requested fragment, membership test did not pass.
495 GNUNET_MULTICAST_REC_ACCESS_DENIED = 3,
498 * Internal error (i.e. database error). Try some other peer.
500 GNUNET_MULTICAST_REC_INTERNAL_ERROR = 4
506 * Replay a message fragment for the multicast group.
508 * @param rh Replay handle identifying which replay operation was requested.
509 * @param msg Replayed message fragment, NULL if unknown/error.
510 * @param ec Error code.
513 GNUNET_MULTICAST_replay (struct GNUNET_MULTICAST_ReplayHandle *rh,
514 const struct GNUNET_MessageHeader *msg,
515 enum GNUNET_MULTICAST_ReplayErrorCode ec);
518 * Function called to provide data for a transmission for a replay.
520 * @see GNUNET_MULTICAST_replay2()
523 (*GNUNET_MULTICAST_ReplayTransmitNotify)(void *cls,
528 * Replay a message for the multicast group.
530 * @param rh Replay handle identifying which replay operation was requested.
531 * @param notify Function to call to get the message.
532 * @param notify_cls Closure for @a notify.
535 GNUNET_MULTICAST_replay2 (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).
552 * @param cfg Configuration to use.
553 * @param priv_key ECC key that will be used to sign messages for this
554 * multicast session; public key is used to identify the multicast group;
555 * FIXME: we'll likely want to use NOT the p521 curve here, but a cheaper
557 * @param last_fragment_id Last fragment ID to continue counting fragments from
558 * when restarting the origin. 0 for a new group.
559 * @param join_cb Function called to approve / disapprove joining of a peer.
560 * @param test_cb Function multicast can use to test group membership.
561 * @param replay_cb Function that can be called to replay a message.
562 * @param request_cb Function called with message fragments from group members.
563 * @param message_cb Function called with the message fragments sent to the
564 * network by GNUNET_MULTICAST_origin_to_all(). These message fragments
565 * should be stored for answering replay requests later.
566 * @param cls Closure for the various callbacks that follow.
567 * @return Handle for the origin, NULL on error.
569 struct GNUNET_MULTICAST_Origin *
570 GNUNET_MULTICAST_origin_start (const struct GNUNET_CONFIGURATION_Handle *cfg,
571 const struct GNUNET_CRYPTO_EccPrivateKey *priv_key,
572 uint64_t last_fragment_id,
573 GNUNET_MULTICAST_JoinCallback join_cb,
574 GNUNET_MULITCAST_MembershipTestCallback test_cb,
575 GNUNET_MULITCAST_ReplayCallback replay_cb,
576 GNUNET_MULTICAST_RequestCallback request_cb,
577 GNUNET_MULTICAST_MessageCallback message_cb,
581 * Function called to provide data for a transmission from the origin to all members.
584 (*GNUNET_MULTICAST_OriginTransmitNotify)(void *cls,
590 * Handle for a request to send a message to all multicast group members
593 struct GNUNET_MULTICAST_OriginMessageHandle;
597 * Send a message to the multicast group.
599 * @param origin Handle to the multicast group.
600 * @param message_id Application layer ID for the message. Opaque to multicast.
601 * @param group_generation Group generation of the message. Documented in
602 * GNUNET_MULTICAST_MessageHeader.
603 * @param size Number of bytes to transmit.
604 * FIXME: Needed? The end of the message can be flagged with a last fragment flag.
605 * @param notify Function to call to get the message.
606 * @param notify_cls Closure for @a notify.
607 * @return NULL on error (i.e. request already pending).
609 struct GNUNET_MULTICAST_OriginMessageHandle *
610 GNUNET_MULTICAST_origin_to_all (struct GNUNET_MULTICAST_Origin *origin,
612 uint64_t group_generation,
614 GNUNET_MULTICAST_OriginTransmitNotify notify,
619 * Cancel request for message transmission to multicast group.
621 * @param mh Request to cancel.
624 GNUNET_MULTICAST_origin_to_all_cancel (struct GNUNET_MULTICAST_OriginMessageHandle *mh);
628 * Stop a multicast group.
630 * @param origin Multicast group to stop.
633 GNUNET_MULTICAST_origin_stop (struct GNUNET_MULTICAST_Origin *origin);
637 * Join a multicast group.
639 * The entity joining is always the local peer. Further information about the
640 * candidate can be provided in the @a join_request message. If the join fails, the
641 * @a message_cb is invoked with a (failure) response and then with NULL. If
642 * the join succeeds, outstanding (state) messages and ongoing multicast
643 * messages will be given to the @a message_cb until the member decides to part
644 * the group. The @a test_cb and @a replay_cb functions may be called at
645 * anytime by the multicast service to support relaying messages to other
646 * members of the group.
648 * @param cfg Configuration to use.
649 * @param group_key ECC public key that identifies the group to join.
650 * @param member_key ECC key that identifies the member and used to sign
651 * requests sent to the origin.
652 * @param origin Peer ID of the origin to send unicast requsets to. If NULL,
653 * unicast requests are sent back via multiple hops on the reverse path
654 * of multicast messages.
655 * @param relay_count Number of peers in the @a relays array.
656 * @param relays Peer identities of members of the group, which serve as relays
657 * and can be used to join the group at. and send the @a join_request to.
658 * If empty, the @a join_request is sent directly to the @a origin.
659 * @param join_request Application-dependent join request to be passed to the peer
660 * @a relay (might, for example, contain a user, bind user
661 * identity/pseudonym to peer identity, application-level message to
663 * @param max_known_fragment_id Largest known message fragment ID to the replay
664 * service; all messages with IDs larger than this ID will be replayed if
665 * possible (lower IDs will be considered known and thus only
666 * be replayed upon explicit request).
667 * FIXME: needed? can be optional or moved to a separate function.
668 * @param join_cb Function called to approve / disapprove joining of a peer.
669 * @param test_cb Function multicast can use to test group membership.
670 * @param replay_cb Function that can be called to replay messages
671 * this peer already knows from this group; NULL if this
672 * client is unable to support replay.
673 * @param message_cb Function to be called for all message fragments we
674 * receive from the group, excluding those our @a replay_cb
676 * @param cls Closure for callbacks.
677 * @return Handle for the member, NULL on error.
679 struct GNUNET_MULTICAST_Member *
680 GNUNET_MULTICAST_member_join (const struct GNUNET_CONFIGURATION_Handle *cfg,
681 const struct GNUNET_CRYPTO_EccPublicKey *group_key,
682 const struct GNUNET_CRYPTO_EccPrivateKey *member_key,
683 const struct GNUNET_PeerIdentity *origin,
685 const struct GNUNET_PeerIdentity *relays,
686 const struct GNUNET_MessageHeader *join_request,
687 uint64_t max_known_fragment_id,
688 GNUNET_MULTICAST_JoinCallback join_cb,
689 GNUNET_MULITCAST_MembershipTestCallback test_cb,
690 GNUNET_MULITCAST_ReplayCallback replay_cb,
691 GNUNET_MULTICAST_MessageCallback message_cb,
696 * Handle for a replay request.
698 struct GNUNET_MULTICAST_MemberReplayHandle;
702 * Request a fragment to be replayed by fragment ID.
704 * Useful if messages below the @e max_known_fragment_id given when joining are
705 * needed and not known to the client.
707 * @param member Membership handle.
708 * @param fragment_id ID of a message fragment that this client would like to
710 * @param flags Additional flags for the replay request. It is used and defined
711 * by the replay callback. FIXME: which replay callback? FIXME: use enum?
712 * FIXME: why not pass reply cb here?
713 * @return Replay request handle, NULL on error.
715 struct GNUNET_MULTICAST_MemberReplayHandle *
716 GNUNET_MULTICAST_member_replay_fragment (struct GNUNET_MULTICAST_Member *member,
717 uint64_t fragment_id,
722 * Request a message fr to be replayed.
724 * Useful if messages below the @e max_known_fragment_id given when joining are
725 * needed and not known to the client.
727 * @param member Membership handle.
728 * @param fragment_id ID of a message fragment that this client would like to
730 * @param message_id ID of a message that this client would like to see
731 * replayed. Typically only one of the @a fragment_id and @a message_id
732 * is given. Specifying a @a message_id would return the last fragment
733 * of the message, which allows requesting the preceding fragments of the
734 * message by looking at the @e fragment_delta header field.
735 * @param flags Additional flags for the replay request. It is used & defined
736 * by the replay callback. E.g. the PSYC service would use this to
737 * implement state synchronization.
738 * @param result_cb Function to be called for the replayed message.
739 * @param result_cb_cls Closure for @a message_cb.
740 * @return Replay request handle, NULL on error.
742 struct GNUNET_MULTICAST_MemberReplayHandle *
743 GNUNET_MULTICAST_member_replay_message (struct GNUNET_MULTICAST_Member *member,
745 uint64_t fragment_offset,
747 GNUNET_MULTICAST_ResultCallback result_cb,
748 void *result_cb_cls);
752 * Cancel a replay request.
754 * @param rh Request to cancel.
757 GNUNET_MULTICAST_member_replay_cancel (struct GNUNET_MULTICAST_MemberReplayHandle *rh);
761 * Part a multicast group.
763 * Disconnects from all group members and invalidates the @a member handle.
765 * An application-dependent part message can be transmitted beforehand using
766 * #GNUNET_MULTICAST_member_to_origin())
768 * @param member Membership handle.
771 GNUNET_MULTICAST_member_part (struct GNUNET_MULTICAST_Member *member);
775 * Function called to provide data for a transmission from a member to the origin.
778 * @param data_size number of bytes available in @a data
779 * @param data where to copy data for transmission
780 * @return number of bytes copied to data
783 (*GNUNET_MULTICAST_MemberTransmitNotify)(void *cls,
789 * Handle for a message to be delivered from a member to the origin.
791 struct GNUNET_MULTICAST_MemberRequestHandle;
795 * Send a message to the origin of the multicast group.
797 * @param member Membership handle.
798 * @param message_id Application layer ID for the message. Opaque to multicast.
799 * @param size Number of bytes we want to send to origin.
800 * @param notify Callback to call to get the message.
801 * @param notify_cls Closure for @a notify.
802 * @return Handle to cancel request, NULL on error (i.e. request already pending).
804 struct GNUNET_MULTICAST_MemberRequestHandle *
805 GNUNET_MULTICAST_member_to_origin (struct GNUNET_MULTICAST_Member *member,
808 GNUNET_MULTICAST_MemberTransmitNotify notify,
813 * Cancel request for message transmission to origin.
815 * @param rh Request to cancel.
818 GNUNET_MULTICAST_member_to_origin_cancel (struct GNUNET_MULTICAST_MemberRequestHandle *rh);
821 #if 0 /* keep Emacsens' auto-indent happy */
828 /* ifndef GNUNET_MULTICAST_SERVICE_H */
830 /* end of gnunet_multicast_service.h */