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diff --git a/src/include/gnunet_multicast_service.h b/src/include/gnunet_multicast_service.h
new file mode 100644
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--- /dev/null
+++ b/src/include/gnunet_multicast_service.h
@@ -0,0 +1,925 @@
+/*
+     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 <http://www.gnu.org/licenses/>.
+
+     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 "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 */