/*
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 .
SPDX-License-Identifier: AGPL3.0-or-later
*/
/**
* @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
#include
/**
* 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 */