/* This file is part of GNUnet. (C) 2012, 2013 Christian Grothoff (and other contributing authors) GNUnet is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, 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 General Public License for more details. You should have received a copy of the GNU General Public License along with GNUnet; see the file COPYING. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /** * @file include/gnunet_multicast_service.h * @brief multicast service; establish tunnels to distant peers * @author Christian Grothoff * @author Gabor X Toth */ #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; /** * Policy flags for the group. */ enum GNUNET_MULTICAST_GroupFlags { /** * Admission must be confirmed by the origin. */ GNUNET_MULTICAST_GROUP_ADMISSION_CONTROL = 1 << 0, /** * Past messages are only available to peers who were a member at the time * they were sent to the group. */ GNUNET_MULTICAST_GROUP_RESTRICTED_HISTORY = 1 << 1, }; /** * Group membership policies. */ enum GNUNET_MULTICAST_GroupPolicy { /** * Anyone can join the group, without announcing his presence; * all messages are always public and can be distributed freely. * Joins may be announced, but this is not required. */ GNUNET_MULTICAST_GROUP_ANONYMOUS = 0, /** * Origin must approve membership to the group, messages must only be * distributed to current group members. This includes the group * state as well as transient messages. */ GNUNET_MULTICAST_GROUP_PRIVATE = GNUNET_MULTICAST_GROUP_ADMISSION_CONTROL | GNUNET_MULTICAST_GROUP_RESTRICTED_HISTORY, #if IDEAS_FOR_FUTURE /** * Anyone can freely join the group (no approval required); * however, messages must only be distributed to current group * members, so the origin must still acknowledge that the member * joined before transient messages are delivered. As approval is * guaranteed, the presistent group state can be synchronized freely * immediately, prior to origin confirmation. */ GNUNET_MULTICAST_GROUP_OPEN = GNUNET_MULTICAST_GROUP_RESTRICTED_HISTORY, /** * Origin must approve membership to the group, but past messages can be * freely distributed to members. */ GNUNET_MULTICAST_GROUP_CLOSED = GNUNET_MULTICAST_GROUP_ADMISSION_CONTROL, , #endif }; 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 }; 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_EccSignature signature; /** * Number of the message fragment, monotonically increasing. */ uint64_t fragment_id GNUNET_PACKED; /** * Number of fragments before the current one that has the same @a message_id. * * 0 for the first fragment of a message. * This allows replaying a message with all of its fragments. */ uint64_t fragment_delta 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. */ enum GNUNET_MULTICAST_MessageFlags flags GNUNET_PACKED; /* Followed by message body. */ }; GNUNET_NETWORK_STRUCT_END GNUNET_NETWORK_STRUCT_BEGIN /** * Header of a request from a member to the origin. * * FIXME: this struct is going to be internal. */ 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_EccPublicKey member_key; /** * ECC signature of the request fragment. * * Signature must match the public key of the multicast group. */ struct GNUNET_CRYPTO_EccSignature signature; /** * Number of the request fragment, monotonically increasing. */ 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 GNUNET_NETWORK_STRUCT_BEGIN /** * Header of a join request sent to the origin or another member. * * FIXME: this struct is going to be internal. */ struct GNUNET_MULTICAST_JoinRequest { /** * Header for the join request. */ struct GNUNET_MessageHeader header; /** * ECC signature of the rest of the fields of the join request. * * Signature must match the public key of the joining member. */ struct GNUNET_CRYPTO_EccSignature signature; /** * Public key of the target group. */ struct GNUNET_CRYPTO_EccPublicKey group_key; /** * Public key of the joining member. */ struct GNUNET_CRYPTO_EccPublicKey member_key; /** * Peer identity of the joining member. */ struct GNUNET_PeerIdentity member_peer; /* Followed by request body. */ }; GNUNET_NETWORK_STRUCT_END /** * Handle that identifies a join request. * * Used to match calls to #GNUNET_MULTICAST_JoinCallback 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_JoinCallback. * * @param jh Join request handle. * @param is_admitted #GNUNET_YES if joining is approved, * #GNUNET_NO if it is disapproved * @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_response 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. */ void GNUNET_MULTICAST_join_decision (struct GNUNET_MULTICAST_JoinHandle *jh, int is_admitted, unsigned int relay_count, const struct GNUNET_PeerIdentity *relays, const struct GNUNET_MessageHeader *join_response); /** * 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 peer Identity of the member that wants to join. * @param join_req Application-dependent join message from the new member * (might, for example, contain a user, * bind user identity/pseudonym to peer identity, application-level * message to origin, etc.). * @param jh Join handle to pass to GNUNET_MULTICAST_join_decison(). */ typedef void (*GNUNET_MULTICAST_JoinCallback) (void *cls, const struct GNUNET_EccPublicKey *member_key, const struct GNUNET_MessageHeader *join_req, struct GNUNET_MULTICAST_JoinHandle *jh); /** * Handle to pass back for the answer of a membership test. */ struct GNUNET_MULTICAST_MembershipTestHandle; /** * Call informing multicast about the decision taken for membership test. * * @param mth Handle that was given for the query. * @param result #GNUNET_YES if peer was a member, #GNUNET_NO if peer was not a member, * #GNUNET_SYSERR if we cannot answer the membership test. */ void GNUNET_MULTICAST_membership_test_result (struct GNUNET_MULTICAST_MembershipTestHandle *mth, int result); /** * Method called to test if a member was in the group at a particular time. * * It is called when a replay request is received to determine if the requested * message can be replayed. * * @param cls Closure. * @param member_id Identity of the member that we want to test. * @param fragment_id Message fragment ID for which we want to do the test. * @param mth Handle to give to GNUNET_MULTICAST_membership_test_answer(). */ typedef void (*GNUNET_MULTICAST_MembershipTestCallback) (void *cls, const struct GNUNET_CRYPTO_EccPublicKey *member_key, uint64_t fragment_id, struct GNUNET_MULTICAST_MembershipTestHandle *mth); /** * Function called whenever a group member has transmitted a request * to the origin (other than joining or leaving). * * @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_EccPublicKey *member_key, const struct GNUNET_MessageHeader *req, enum GNUNET_MULTICAST_MessageFlags flags); /** * 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. * * @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 to be replayed. * * 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 fragment_id Which message fragment should be replayed. * @param rh Handle to pass to message transmit function. */ typedef void (*GNUNET_MULTICAST_ReplayCallback) (void *cls, uint64_t fragment_id, struct GNUNET_MULTICAST_ReplayHandle *rh); /** * Possible error codes during replay. */ enum GNUNET_MULTICAST_ReplayErrorCode { /** * Everything is fine. */ GNUNET_MULTICAST_REC_OK = 0, /** * Message fragment has been discarded (likely transient message that was too old). */ GNUNET_MULTICAST_REC_TRANSIENT_LOST = 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. */ GNUNET_MULTICAST_REC_PAST_HEAD = 2, /** * Internal error (i.e. database error). Try some other peer. */ GNUNET_MULTICAST_REC_INTERNAL_ERROR = 3 }; /** * Replay a message from the multicast group. * * @param rh Replay handle identifying which replay operation was requested. * @param msg Replayed message fragment, NULL if unknown/error. * @param ec Error code. */ void GNUNET_MULTICAST_replay (struct GNUNET_MULTICAST_ReplayHandle *rh, const struct GNUNET_MULTICAST_MessageHeader *msg, enum GNUNET_MULTICAST_ReplayErrorCode ec); /** * Start a multicast group. * * Will advertise the origin in the P2P overlay network under the respective * public key so that other peer can find this peer to join it. Peers that * issue GNUNET_MULTICAST_member_join() can then transmit a join request to * either an existing group member (if the @a policy is permissive) 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 (one at a time). * * @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; * FIXME: we'll likely want to use NOT the p521 curve here, but a cheaper * one in the future. * @param policy Group policy specifying join and history restrictions. * @param last_fragment_id Last fragment ID to continue counting fragments from * when restarting the origin. 0 for a new group. * @param join_cb Function called to approve / disapprove joining of a peer. * @param test_cb Function multicast can use to test group membership. * @param replay_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_EccPrivateKey *priv_key, enum GNUNET_MULTICAST_GroupPolicy policy, uint64_t last_fragment_id, GNUNET_MULTICAST_JoinCallback join_cb, GNUNET_MULITCAST_MembershipTestCallback test_cb, GNUNET_MULITCAST_ReplayCallback replay_cb, GNUNET_MULTICAST_RequestCallback request_cb, GNUNET_MULTICAST_MessageCallback message_cb, void *cls); /** * Handle for a request to send a message to all multicast group members * (from the origin). */ struct GNUNET_MULTICAST_OriginMessageHandle; /** * 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 * GNUNET_MULTICAST_MessageHeader. * @param size Number of bytes to transmit. * FIXME: Needed? The end of the message can be flagged with a last fragment flag. * @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). */ struct GNUNET_MULTICAST_OriginMessageHandle * GNUNET_MULTICAST_origin_to_all (struct GNUNET_MULTICAST_Origin *origin, uint64_t message_id, uint64_t group_generation, size_t size, GNUNET_CONNECTION_TransmitReadyNotify notify, void *notify_cls); /** * Cancel request for message transmission to multicast group. * * @param mh Request to cancel. */ void GNUNET_MULTICAST_origin_to_all_cancel (struct GNUNET_MULTICAST_OriginMessageHandle *mh); /** * Stop a multicast group. * * @param origin Multicast group to stop. */ void GNUNET_MULTICAST_origin_stop (struct GNUNET_MULTICAST_Origin *origin); /** * Join a multicast group. * * The entity joining is always the local peer. Further information about the * candidate can be provided in the @a join_request message. 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 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_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_request Application-dependent join request to be passed to the peer * @a relay (might, for example, contain a user, bind user * identity/pseudonym to peer identity, application-level message to * origin, etc.). * @param max_known_fragment_id Largest known message fragment ID to the replay * service; all messages with IDs larger than this ID will be replayed if * possible (lower IDs will be considered known and thus only * be replayed upon explicit request). * FIXME: needed? can be optional or moved to a separate function. * @param join_cb Function called to approve / disapprove joining of a peer. * @param test_cb Function multicast can use to test group membership. * @param replay_cb Function that can be called to replay messages * 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_EccPublicKey *group_key, const struct GNUNET_CRYPTO_EccPrivateKey *member_key, const struct GNUNET_PeerIdentity *origin, size_t relay_count, const struct GNUNET_PeerIdentity *relays, const struct GNUNET_MessageHeader *join_request, uint64_t max_known_fragment_id, GNUNET_MULTICAST_JoinCallback join_cb, GNUNET_MULITCAST_MembershipTestCallback test_cb, GNUNET_MULITCAST_ReplayCallback replay_cb, GNUNET_MULTICAST_MessageCallback message_cb, void *cls); /** * Handle for a replay request. */ struct GNUNET_MULTICAST_MemberReplayHandle; /** * Request a message 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 a message that this client would like to see replayed. * @param message_cb Function to be called for the replayed message. * @param message_cb_cls Closure for @a message_cb. * @return Replay request handle, NULL on error. */ struct GNUNET_MULTICAST_MemberReplayHandle * GNUNET_MULTICAST_member_request_replay (struct GNUNET_MULTICAST_Member *member, uint64_t message_id, GNUNET_MULTICAST_MessageCallback message_cb, void *message_cb_cls); /** * Cancel a replay request. * * @param rh Request to cancel. */ void GNUNET_MULTICAST_member_request_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); /** * Handle for a message to be delivered from a member to the origin. */ struct GNUNET_MULTICAST_MemberRequestHandle; /** * Send a message to the origin of the multicast group. * * @param member Membership handle. * @param message_id Application layer ID for the message. Opaque to multicast. * @param size Number of bytes we want to send to origin. * @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). */ struct GNUNET_MULTICAST_MemberRequestHandle * GNUNET_MULTICAST_member_to_origin (struct GNUNET_MULTICAST_Member *member, uint64_t message_id, size_t size, GNUNET_CONNECTION_TransmitReadyNotify notify, void *notify_cls); /** * Cancel request for message transmission to origin. * * @param rh Request to cancel. */ void GNUNET_MULTICAST_member_to_origin_cancel (struct GNUNET_MULTICAST_MemberRequestHandle *rh); #if 0 /* keep Emacsens' auto-indent happy */ { #endif #ifdef __cplusplus } #endif /* ifndef GNUNET_MULTICAST_SERVICE_H */ #endif /* end of gnunet_multicast_service.h */