/* This file is part of GNUnet. Copyright (C) 2012, 2013 GNUnet e.V. GNUnet is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. GNUnet is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program. If not, see . */ /** * @author Gabor X Toth * @author Christian Grothoff * * @file * Multicast service; multicast messaging via CADET * * @defgroup multicast Multicast service * Multicast messaging via CADET. * @{ */ #ifndef GNUNET_MULTICAST_SERVICE_H #define GNUNET_MULTICAST_SERVICE_H #ifdef __cplusplus extern "C" { #if 0 /* keep Emacsens' auto-indent happy */ } #endif #endif #include "gnunet_util_lib.h" #include "gnunet_transport_service.h" /** * Version number of GNUnet-multicast API. */ #define GNUNET_MULTICAST_VERSION 0x00000000 /** * Opaque handle for a multicast group member. */ struct GNUNET_MULTICAST_Member; /** * Handle for the origin of a multicast group. */ struct GNUNET_MULTICAST_Origin; enum GNUNET_MULTICAST_MessageFlags { /** * First fragment of a message. */ GNUNET_MULTICAST_MESSAGE_FIRST_FRAGMENT = 1 << 0, /** * Last fragment of a message. */ GNUNET_MULTICAST_MESSAGE_LAST_FRAGMENT = 1 << 1, /** * OR'ed flags if message is not fragmented. */ GNUNET_MULTICAST_MESSAGE_NOT_FRAGMENTED = GNUNET_MULTICAST_MESSAGE_FIRST_FRAGMENT | GNUNET_MULTICAST_MESSAGE_LAST_FRAGMENT, /** * Historic message, used only locally when replaying messages from local * storage. */ GNUNET_MULTICAST_MESSAGE_HISTORIC = 1 << 30 }; GNUNET_NETWORK_STRUCT_BEGIN /** * Header of a multicast message fragment. * * This format is public as the replay mechanism must replay message fragments using the * same format. This is needed as we want to integrity-check message fragments within * the multicast layer to avoid multicasting mal-formed messages. */ struct GNUNET_MULTICAST_MessageHeader { /** * Header for all multicast message fragments from the origin. */ struct GNUNET_MessageHeader header; /** * Number of hops this message fragment has taken since the origin. * * Helpful to determine shortest paths to the origin among honest peers for * unicast requests from members. Updated at each hop and thus not signed and * not secure. */ uint32_t hop_counter GNUNET_PACKED; /** * ECC signature of the message fragment. * * Signature must match the public key of the multicast group. */ struct GNUNET_CRYPTO_EddsaSignature signature; /** * Purpose for the signature and size of the signed data. */ struct GNUNET_CRYPTO_EccSignaturePurpose purpose; /** * Number of the message fragment, monotonically increasing starting from 1. */ uint64_t fragment_id GNUNET_PACKED; /** * Byte offset of this @e fragment of the @e message. */ uint64_t fragment_offset GNUNET_PACKED; /** * Number of the message this fragment belongs to. * * Set in GNUNET_MULTICAST_origin_to_all(). */ uint64_t message_id GNUNET_PACKED; /** * Counter that monotonically increases whenever a member parts the group. * * Set in GNUNET_MULTICAST_origin_to_all(). * * It has significance in case of replay requests: when a member has missed * messages and gets a replay request: in this case if the @a group_generation * is still the same before and after the missed messages, it means that no * @e join or @e part operations happened during the missed messages. */ uint64_t group_generation GNUNET_PACKED; /** * Flags for this message fragment. * * @see enum GNUNET_MULTICAST_MessageFlags */ uint32_t flags GNUNET_PACKED; /* Followed by message body. */ }; /** * Header of a request from a member to the origin. */ struct GNUNET_MULTICAST_RequestHeader { /** * Header for all requests from a member to the origin. */ struct GNUNET_MessageHeader header; /** * Public key of the sending member. */ struct GNUNET_CRYPTO_EcdsaPublicKey member_pub_key; /** * ECC signature of the request fragment. * * Signature must match the public key of the multicast group. */ struct GNUNET_CRYPTO_EcdsaSignature signature; /** * Purpose for the signature and size of the signed data. */ struct GNUNET_CRYPTO_EccSignaturePurpose purpose; /** * Number of the request fragment. * Monotonically increasing from 1. */ uint64_t fragment_id GNUNET_PACKED; /** * Byte offset of this @e fragment of the @e request. */ uint64_t fragment_offset GNUNET_PACKED; /** * Number of the request this fragment belongs to. * * Set in GNUNET_MULTICAST_origin_to_all(). */ uint64_t request_id GNUNET_PACKED; /** * Flags for this request. */ enum GNUNET_MULTICAST_MessageFlags flags GNUNET_PACKED; /* Followed by request body. */ }; GNUNET_NETWORK_STRUCT_END /** * Maximum size of a multicast message fragment. */ #define GNUNET_MULTICAST_FRAGMENT_MAX_SIZE (63 * 1024) #define GNUNET_MULTICAST_FRAGMENT_MAX_PAYLOAD \ (GNUNET_MULTICAST_FRAGMENT_MAX_SIZE \ - sizeof (struct GNUNET_MULTICAST_MessageHeader)) /** * Handle that identifies a join request. * * Used to match calls to #GNUNET_MULTICAST_JoinRequestCallback to the * corresponding calls to #GNUNET_MULTICAST_join_decision(). */ struct GNUNET_MULTICAST_JoinHandle; /** * Function to call with the decision made for a join request. * * Must be called once and only once in response to an invocation of the * #GNUNET_MULTICAST_JoinRequestCallback. * * @param jh * Join request handle. * @param is_admitted * #GNUNET_YES if the join is approved, * #GNUNET_NO if it is disapproved, * #GNUNET_SYSERR if we cannot answer the request. * @param relay_count * Number of relays given. * @param relays * Array of suggested peers that might be useful relays to use * when joining the multicast group (essentially a list of peers that * are already part of the multicast group and might thus be willing * to help with routing). If empty, only this local peer (which must * be the multicast origin) is a good candidate for building the * multicast tree. Note that it is unnecessary to specify our own * peer identity in this array. * @param join_resp * Message to send in response to the joining peer; * can also be used to redirect the peer to a different group at the * application layer; this response is to be transmitted to the * peer that issued the request even if admission is denied. */ struct GNUNET_MULTICAST_ReplayHandle * GNUNET_MULTICAST_join_decision (struct GNUNET_MULTICAST_JoinHandle *jh, int is_admitted, uint16_t relay_count, const struct GNUNET_PeerIdentity *relays, const struct GNUNET_MessageHeader *join_resp); /** * Method called whenever another peer wants to join the multicast group. * * Implementations of this function must call GNUNET_MULTICAST_join_decision() * with the decision. * * @param cls * Closure. * @param member_pub_key * Public key of the member requesting join. * @param join_msg * Application-dependent join message from the new member. * @param jh * Join handle to pass to GNUNET_MULTICAST_join_decison(). */ typedef void (*GNUNET_MULTICAST_JoinRequestCallback) (void *cls, const struct GNUNET_CRYPTO_EcdsaPublicKey *member_pub_key, const struct GNUNET_MessageHeader *join_msg, struct GNUNET_MULTICAST_JoinHandle *jh); /** * Method called to inform about the decision in response to a join request. * * If @a is_admitted is not #GNUNET_YES, then the multicast service disconnects * the client and the multicast member handle returned by * GNUNET_MULTICAST_member_join() is invalidated. * * @param cls * Closure. * @param is_admitted * #GNUNET_YES or #GNUNET_NO or #GNUNET_SYSERR * @param peer * The peer we are connected to and the join decision is from. * @param relay_count * Number of peers in the @a relays array. * @param relays * Peer identities of members of the group, which serve as relays * and can be used to join the group at. If empty, only the origin can * be used to connect to the group. * @param join_msg * Application-dependent join message from the origin. */ typedef void (*GNUNET_MULTICAST_JoinDecisionCallback) (void *cls, int is_admitted, const struct GNUNET_PeerIdentity *peer, uint16_t relay_count, const struct GNUNET_PeerIdentity *relays, const struct GNUNET_MessageHeader *join_msg); /** * Function called whenever a group member has transmitted a request * to the origin (other than joining or leaving). * * FIXME: need to distinguish between origin cancelling a message (some fragments * were sent, then the rest 'discarded') and the case where we got disconnected; * right now, both would mean 'msg' is NULL, but they could be quite different... * So the semantics from the receiver side of * GNUNET_MULTICAST_member_to_origin_cancel() are not clear here. Maybe we * should do something with the flags in this case? * * @param cls * Closure (set from GNUNET_MULTICAST_origin_start). * @param sender * Identity of the sender. * @param req * Request to the origin. * @param flags * Flags for the request. */ typedef void (*GNUNET_MULTICAST_RequestCallback) (void *cls, const struct GNUNET_MULTICAST_RequestHeader *req); /** * Function called whenever a group member is receiving a message fragment from * the origin. * * If admission to the group is denied, this function is called once with the * response of the @e origin (as given to GNUNET_MULTICAST_join_decision()) and * then a second time with NULL to indicate that the connection failed for good. * * FIXME: need to distinguish between origin cancelling a message (some fragments * were sent, then the rest 'discarded') and the case where we got disconnected; * right now, both would mean 'msg' is NULL, but they could be quite different... * So the semantics from the receiver side of * GNUNET_MULTICAST_origin_to_all_cancel() are not clear here. * * @param cls * Closure (set from GNUNET_MULTICAST_member_join()) * @param msg * Message from the origin, NULL if the origin shut down * (or we were kicked out, and we should thus call * GNUNET_MULTICAST_member_part() next) */ typedef void (*GNUNET_MULTICAST_MessageCallback) (void *cls, const struct GNUNET_MULTICAST_MessageHeader *msg); /** * Opaque handle to a replay request from the multicast service. */ struct GNUNET_MULTICAST_ReplayHandle; /** * Functions with this signature are called whenever the multicast service needs * a message fragment to be replayed by fragment_id. * * Implementations of this function MUST call GNUNET_MULTICAST_replay() ONCE * (with a message or an error); however, if the origin is destroyed or the * group is left, the replay handle must no longer be used. * * @param cls * Closure (set from GNUNET_MULTICAST_origin_start() * or GNUNET_MULTICAST_member_join()). * @param member_pub_key * The member requesting replay. * @param fragment_id * Which message fragment should be replayed. * @param flags * Flags for the replay. * @param rh * Handle to pass to message transmit function. */ typedef void (*GNUNET_MULTICAST_ReplayFragmentCallback) (void *cls, const struct GNUNET_CRYPTO_EcdsaPublicKey *member_pub_key, uint64_t fragment_id, uint64_t flags, struct GNUNET_MULTICAST_ReplayHandle *rh); /** * Functions with this signature are called whenever the multicast service needs * a message fragment to be replayed by message_id and fragment_offset. * * Implementations of this function MUST call GNUNET_MULTICAST_replay() ONCE * (with a message or an error); however, if the origin is destroyed or the * group is left, the replay handle must no longer be used. * * @param cls * Closure (set from GNUNET_MULTICAST_origin_start() * or GNUNET_MULTICAST_member_join()). * @param member_pub_key * The member requesting replay. * @param message_id * Which message should be replayed. * @param fragment_offset * Offset of the fragment within of @a message_id to be replayed. * @param flags * Flags for the replay. * @param rh * Handle to pass to message transmit function. */ typedef void (*GNUNET_MULTICAST_ReplayMessageCallback) (void *cls, const struct GNUNET_CRYPTO_EcdsaPublicKey *member_pub_key, uint64_t message_id, uint64_t fragment_offset, uint64_t flags, struct GNUNET_MULTICAST_ReplayHandle *rh); /** * Possible error codes during replay. */ enum GNUNET_MULTICAST_ReplayErrorCode { /** * Everything is fine. */ GNUNET_MULTICAST_REC_OK = 0, /** * Message fragment not found in the message store. * * Either discarded if it is too old, or not arrived yet if this member has * missed some messages. */ GNUNET_MULTICAST_REC_NOT_FOUND = 1, /** * Fragment ID counter was larger than the highest counter this * replay function has ever encountered; thus it is likely the * origin never sent it and we're at the HEAD of the multicast * stream as far as this node is concerned. * * FIXME: needed? */ GNUNET_MULTICAST_REC_PAST_HEAD = 2, /** * Access is denied to the requested fragment, membership test did not pass. */ GNUNET_MULTICAST_REC_ACCESS_DENIED = 3, /** * Internal error (i.e. database error). Try some other peer. */ GNUNET_MULTICAST_REC_INTERNAL_ERROR = 4 }; /** * Replay a message fragment for the multicast group. * * @param rh * Replay handle identifying which replay operation was requested. * @param msg * Replayed message fragment, NULL if not found / an error occurred. * @param ec * Error code. See enum GNUNET_MULTICAST_ReplayErrorCode * If not #GNUNET_MULTICAST_REC_OK, the replay handle is invalidated. */ void GNUNET_MULTICAST_replay_response (struct GNUNET_MULTICAST_ReplayHandle *rh, const struct GNUNET_MessageHeader *msg, enum GNUNET_MULTICAST_ReplayErrorCode ec); /** * Indicate the end of the replay session. * * Invalidates the replay handle. * * @param rh Replay session to end. */ void GNUNET_MULTICAST_replay_response_end (struct GNUNET_MULTICAST_ReplayHandle *rh); /** * Function called to provide data for a transmission for a replay. * * @see GNUNET_MULTICAST_replay2() */ typedef int (*GNUNET_MULTICAST_ReplayTransmitNotify) (void *cls, size_t *data_size, void *data); /** * Replay a message for the multicast group. * * @param rh * Replay handle identifying which replay operation was requested. * @param notify * Function to call to get the message. * @param notify_cls * Closure for @a notify. */ void GNUNET_MULTICAST_replay_response2 (struct GNUNET_MULTICAST_ReplayHandle *rh, GNUNET_MULTICAST_ReplayTransmitNotify notify, void *notify_cls); /** * Start a multicast group. * * Peers that issue GNUNET_MULTICAST_member_join() can transmit a join request * to either an existing group member or to the origin. If the joining is * approved, the member is cleared for @e replay and will begin to receive * messages transmitted to the group. If joining is disapproved, the failed * candidate will be given a response. Members in the group can send messages * to the origin. * * TODO: This function could optionally offer to advertise the origin in the * P2P overlay network(where?) under the respective public key so that other * peers can find an alternate PeerId to join it. Higher level protocols may * however provide other means of solving the problem of the offline host * (see secushare specs about that) and therefore merely need a way to provide * a list of possible PeerIds. * * @param cfg * Configuration to use. * @param priv_key * ECC key that will be used to sign messages for this * multicast session; public key is used to identify the multicast group; * @param max_fragment_id * Maximum fragment ID already sent to the group. * 0 for a new group. * @param join_request_cb * Function called to approve / disapprove joining of a peer. * @param replay_frag_cb * Function that can be called to replay a message fragment. * @param replay_msg_cb * Function that can be called to replay a message. * @param request_cb * Function called with message fragments from group members. * @param message_cb * Function called with the message fragments sent to the * network by GNUNET_MULTICAST_origin_to_all(). These message fragments * should be stored for answering replay requests later. * @param cls * Closure for the various callbacks that follow. * * @return Handle for the origin, NULL on error. */ struct GNUNET_MULTICAST_Origin * GNUNET_MULTICAST_origin_start (const struct GNUNET_CONFIGURATION_Handle *cfg, const struct GNUNET_CRYPTO_EddsaPrivateKey *priv_key, uint64_t max_fragment_id, GNUNET_MULTICAST_JoinRequestCallback join_request_cb, GNUNET_MULTICAST_ReplayFragmentCallback replay_frag_cb, GNUNET_MULTICAST_ReplayMessageCallback replay_msg_cb, GNUNET_MULTICAST_RequestCallback request_cb, GNUNET_MULTICAST_MessageCallback message_cb, void *cls); /** * Function called to provide data for a transmission from the origin to all * members. * * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO) * invalidates the respective transmission handle. * * @param cls * Closure. * @param[in,out] data_size * Initially set to the number of bytes available in * @a data, should be set to the number of bytes written to data. * @param[out] data * Where to write the body of the message to give to the * method. The function must copy at most @a data_size bytes to @a data. * * @return #GNUNET_SYSERR on error (fatal, aborts transmission) * #GNUNET_NO on success, if more data is to be transmitted later. * Should be used if @a data_size was not big enough to take all the * data. If 0 is returned in @a data_size the transmission is paused, * and can be resumed with GNUNET_MULTICAST_origin_to_all_resume(). * #GNUNET_YES if this completes the transmission (all data supplied) * @deprecated should move to MQ-style API! */ typedef int (*GNUNET_MULTICAST_OriginTransmitNotify) (void *cls, size_t *data_size, void *data); /** * Handle for a request to send a message to all multicast group members * (from the origin). */ struct GNUNET_MULTICAST_OriginTransmitHandle; /** * Send a message to the multicast group. * * @param origin * Handle to the multicast group. * @param message_id * Application layer ID for the message. Opaque to multicast. * @param group_generation * Group generation of the message. Documented in * struct GNUNET_MULTICAST_MessageHeader. * @param notify * Function to call to get the message. * @param notify_cls * Closure for @a notify. * * @return NULL on error (i.e. request already pending). * @deprecated should move to MQ-style API! */ struct GNUNET_MULTICAST_OriginTransmitHandle * GNUNET_MULTICAST_origin_to_all (struct GNUNET_MULTICAST_Origin *origin, uint64_t message_id, uint64_t group_generation, GNUNET_MULTICAST_OriginTransmitNotify notify, void *notify_cls); /** * Resume message transmission to multicast group. * * @param th Transmission to cancel. */ void GNUNET_MULTICAST_origin_to_all_resume (struct GNUNET_MULTICAST_OriginTransmitHandle *th); /** * Cancel request for message transmission to multicast group. * * @param th Transmission to cancel. */ void GNUNET_MULTICAST_origin_to_all_cancel (struct GNUNET_MULTICAST_OriginTransmitHandle *th); /** * Stop a multicast group. * * @param origin Multicast group to stop. */ void GNUNET_MULTICAST_origin_stop (struct GNUNET_MULTICAST_Origin *origin, GNUNET_ContinuationCallback stop_cb, void *stop_cls); /** * Join a multicast group. * * The entity joining is always the local peer. Further information about the * candidate can be provided in @a join_msg. If the join fails, the * @a message_cb is invoked with a (failure) response and then with NULL. If * the join succeeds, outstanding (state) messages and ongoing multicast * messages will be given to the @a message_cb until the member decides to part * the group. The @a mem_test_cb and @a replay_cb functions may be called at * anytime by the multicast service to support relaying messages to other * members of the group. * * @param cfg * Configuration to use. * @param group_key * ECC public key that identifies the group to join. * @param member_pub_key * ECC key that identifies the member * and used to sign requests sent to the origin. * @param origin * Peer ID of the origin to send unicast requsets to. If NULL, * unicast requests are sent back via multiple hops on the reverse path * of multicast messages. * @param relay_count * Number of peers in the @a relays array. * @param relays * Peer identities of members of the group, which serve as relays * and can be used to join the group at. and send the @a join_request to. * If empty, the @a join_request is sent directly to the @a origin. * @param join_msg * Application-dependent join message to be passed to the peer @a origin. * @param join_request_cb * Function called to approve / disapprove joining of a peer. * @param join_decision_cb * Function called to inform about the join decision. * @param replay_frag_cb * Function that can be called to replay message fragments * this peer already knows from this group. NULL if this * client is unable to support replay. * @param replay_msg_cb * Function that can be called to replay message fragments * this peer already knows from this group. NULL if this * client is unable to support replay. * @param message_cb * Function to be called for all message fragments we * receive from the group, excluding those our @a replay_cb * already has. * @param cls * Closure for callbacks. * * @return Handle for the member, NULL on error. */ struct GNUNET_MULTICAST_Member * GNUNET_MULTICAST_member_join (const struct GNUNET_CONFIGURATION_Handle *cfg, const struct GNUNET_CRYPTO_EddsaPublicKey *group_key, const struct GNUNET_CRYPTO_EcdsaPrivateKey *member_pub_key, const struct GNUNET_PeerIdentity *origin, uint16_t relay_count, const struct GNUNET_PeerIdentity *relays, const struct GNUNET_MessageHeader *join_request, GNUNET_MULTICAST_JoinRequestCallback join_request_cb, GNUNET_MULTICAST_JoinDecisionCallback join_decision_cb, GNUNET_MULTICAST_ReplayFragmentCallback replay_frag_cb, GNUNET_MULTICAST_ReplayMessageCallback replay_msg_cb, GNUNET_MULTICAST_MessageCallback message_cb, void *cls); /** * Handle for a replay request. */ struct GNUNET_MULTICAST_MemberReplayHandle; /** * Request a fragment to be replayed by fragment ID. * * Useful if messages below the @e max_known_fragment_id given when joining are * needed and not known to the client. * * @param member * Membership handle. * @param fragment_id * ID of a message fragment that this client would like to see replayed. * @param flags * Additional flags for the replay request. * It is used and defined by GNUNET_MULTICAST_ReplayFragmentCallback * * @return Replay request handle, NULL on error. */ struct GNUNET_MULTICAST_MemberReplayHandle * GNUNET_MULTICAST_member_replay_fragment (struct GNUNET_MULTICAST_Member *member, uint64_t fragment_id, uint64_t flags); /** * Request a message fr to be replayed. * * Useful if messages below the @e max_known_fragment_id given when joining are * needed and not known to the client. * * @param member * Membership handle. * @param message_id * ID of the message this client would like to see replayed. * @param fragment_offset * Offset of the fragment within the message to replay. * @param flags * Additional flags for the replay request. * It is used & defined by GNUNET_MULTICAST_ReplayMessageCallback * * @return Replay request handle, NULL on error. */ struct GNUNET_MULTICAST_MemberReplayHandle * GNUNET_MULTICAST_member_replay_message (struct GNUNET_MULTICAST_Member *member, uint64_t message_id, uint64_t fragment_offset, uint64_t flags); /** * Cancel a replay request. * * @param rh * Request to cancel. */ void GNUNET_MULTICAST_member_replay_cancel (struct GNUNET_MULTICAST_MemberReplayHandle *rh); /** * Part a multicast group. * * Disconnects from all group members and invalidates the @a member handle. * * An application-dependent part message can be transmitted beforehand using * #GNUNET_MULTICAST_member_to_origin()) * * @param member * Membership handle. */ void GNUNET_MULTICAST_member_part (struct GNUNET_MULTICAST_Member *member, GNUNET_ContinuationCallback part_cb, void *part_cls); /** * Function called to provide data for a transmission from a member to the origin. * * Note that returning #GNUNET_OK or #GNUNET_SYSERR (but not #GNUNET_NO) * invalidates the respective transmission handle. * * @param cls * Closure. * @param[in,out] data_size * Initially set to the number of bytes available in * @a data, should be set to the number of bytes written to data. * @param[out] data * Where to write the body of the message to give to the * method. The function must copy at most @a data_size bytes to @a data. * * @return #GNUNET_SYSERR on error (fatal, aborts transmission) * #GNUNET_NO on success, if more data is to be transmitted later. * Should be used if @a data_size was not big enough to take all the * data. If 0 is returned in @a data_size the transmission is paused, * and can be resumed with GNUNET_MULTICAST_member_to_origin_resume(). * #GNUNET_YES if this completes the transmission (all data supplied) * @deprecated should move to MQ-style API! */ typedef int (*GNUNET_MULTICAST_MemberTransmitNotify) (void *cls, size_t *data_size, void *data); /** * Handle for a message to be delivered from a member to the origin. */ struct GNUNET_MULTICAST_MemberTransmitHandle; /** * Send a message to the origin of the multicast group. * * @param member * Membership handle. * @param request_id * Application layer ID for the request. Opaque to multicast. * @param notify * Callback to call to get the message. * @param notify_cls * Closure for @a notify. * * @return Handle to cancel request, NULL on error (i.e. request already pending). * @deprecated should move to MQ-style API! */ struct GNUNET_MULTICAST_MemberTransmitHandle * GNUNET_MULTICAST_member_to_origin (struct GNUNET_MULTICAST_Member *member, uint64_t request_id, GNUNET_MULTICAST_MemberTransmitNotify notify, void *notify_cls); /** * Resume message transmission to origin. * * @param th * Transmission to cancel. */ void GNUNET_MULTICAST_member_to_origin_resume (struct GNUNET_MULTICAST_MemberTransmitHandle *th); /** * Cancel request for message transmission to origin. * * @param th * Transmission to cancel. */ void GNUNET_MULTICAST_member_to_origin_cancel (struct GNUNET_MULTICAST_MemberTransmitHandle *th); #if 0 /* keep Emacsens' auto-indent happy */ { #endif #ifdef __cplusplus } #endif /* ifndef GNUNET_MULTICAST_SERVICE_H */ #endif /** @} */ /* end of group */