Imported Upstream version 0.9.2upstream/0.9.2

1 files changed, 826 insertions, 0 deletions

diff --git a/src/core/gnunet-service-core_sessions.c b/src/core/gnunet-service-core_sessions.c
new file mode 100644
index 0000000..1f697cf
--- /dev/null
+++ b/src/core/gnunet-service-core_sessions.c
@@ -0,0 +1,826 @@
+/*
+     This file is part of GNUnet.
+     (C) 2009, 2010, 2011 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 core/gnunet-service-core_sessions.c
+ * @brief code for managing of 'encrypted' sessions (key exchange done)
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "gnunet-service-core.h"
+#include "gnunet-service-core_neighbours.h"
+#include "gnunet-service-core_kx.h"
+#include "gnunet-service-core_typemap.h"
+#include "gnunet-service-core_sessions.h"
+#include "gnunet-service-core_clients.h"
+#include "gnunet_constants.h"
+
+/**
+ * How often do we transmit our typemap?
+ */
+#define TYPEMAP_FREQUENCY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 5)
+
+
+/**
+ * Message ready for encryption.  This struct is followed by the
+ * actual content of the message.
+ */
+struct SessionMessageEntry
+{
+
+  /**
+   * We keep messages in a doubly linked list.
+   */
+  struct SessionMessageEntry *next;
+
+  /**
+   * We keep messages in a doubly linked list.
+   */
+  struct SessionMessageEntry *prev;
+
+  /**
+   * Deadline for transmission, 1s after we received it (if we
+   * are not corking), otherwise "now".  Note that this message
+   * does NOT expire past its deadline.
+   */
+  struct GNUNET_TIME_Absolute deadline;
+
+  /**
+   * How long is the message? (number of bytes following the "struct
+   * MessageEntry", but not including the size of "struct
+   * MessageEntry" itself!)
+   */
+  size_t size;
+
+};
+
+
+/**
+ * Data kept per session.
+ */
+struct Session
+{
+  /**
+   * Identity of the other peer.
+   */
+  struct GNUNET_PeerIdentity peer;
+
+  /**
+   * Head of list of requests from clients for transmission to
+   * this peer.
+   */
+  struct GSC_ClientActiveRequest *active_client_request_head;
+
+  /**
+   * Tail of list of requests from clients for transmission to
+   * this peer.
+   */
+  struct GSC_ClientActiveRequest *active_client_request_tail;
+
+  /**
+   * Head of list of messages ready for encryption.
+   */
+  struct SessionMessageEntry *sme_head;
+
+  /**
+   * Tail of list of messages ready for encryption.
+   */
+  struct SessionMessageEntry *sme_tail;
+
+  /**
+   * Information about the key exchange with the other peer.
+   */
+  struct GSC_KeyExchangeInfo *kxinfo;
+
+  /**
+   * Current type map for this peer.
+   */
+  struct GSC_TypeMap *tmap;
+
+  /**
+   * At what time did we initially establish this session?
+   * (currently unused, should be integrated with ATS in the
+   * future...).
+   */
+  struct GNUNET_TIME_Absolute time_established;
+
+  /**
+   * Task to transmit corked messages with a delay.
+   */
+  GNUNET_SCHEDULER_TaskIdentifier cork_task;
+
+  /**
+   * Task to transmit our type map.
+   */
+  GNUNET_SCHEDULER_TaskIdentifier typemap_task;
+
+  /**
+   * Is the neighbour queue empty and thus ready for us
+   * to transmit an encrypted message?
+   */
+  int ready_to_transmit;
+
+};
+
+
+/**
+ * Map of peer identities to 'struct Session'.
+ */
+static struct GNUNET_CONTAINER_MultiHashMap *sessions;
+
+
+/**
+ * Find the session for the given peer.
+ *
+ * @param peer identity of the peer
+ * @return NULL if we are not connected, otherwise the
+ *         session handle
+ */
+static struct Session *
+find_session (const struct GNUNET_PeerIdentity *peer)
+{
+  return GNUNET_CONTAINER_multihashmap_get (sessions, &peer->hashPubKey);
+}
+
+
+/**
+ * End the session with the given peer (we are no longer
+ * connected).
+ *
+ * @param pid identity of peer to kill session with
+ */
+void
+GSC_SESSIONS_end (const struct GNUNET_PeerIdentity *pid)
+{
+  struct Session *session;
+  struct GSC_ClientActiveRequest *car;
+  struct SessionMessageEntry *sme;
+
+  session = find_session (pid);
+  if (NULL == session)
+    return;
+#if DEBUG_CORE
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Destroying session for peer `%4s'\n",
+              GNUNET_i2s (&session->peer));
+#endif
+  if (GNUNET_SCHEDULER_NO_TASK != session->cork_task)
+  {
+    GNUNET_SCHEDULER_cancel (session->cork_task);
+    session->cork_task = GNUNET_SCHEDULER_NO_TASK;
+  }
+  while (NULL != (car = session->active_client_request_head))
+  {
+    GNUNET_CONTAINER_DLL_remove (session->active_client_request_head,
+                                 session->active_client_request_tail, car);
+    GSC_CLIENTS_reject_request (car);
+  }
+  while (NULL != (sme = session->sme_head))
+  {
+    GNUNET_CONTAINER_DLL_remove (session->sme_head, session->sme_tail, sme);
+    GNUNET_free (sme);
+  }
+  GNUNET_SCHEDULER_cancel (session->typemap_task);
+  GSC_CLIENTS_notify_clients_about_neighbour (&session->peer, NULL,
+                                              0 /* FIXME: ATSI */ ,
+                                              session->tmap, NULL);
+  GNUNET_assert (GNUNET_YES ==
+                 GNUNET_CONTAINER_multihashmap_remove (sessions,
+                                                       &session->
+                                                       peer.hashPubKey,
+                                                       session));
+  GNUNET_STATISTICS_set (GSC_stats, gettext_noop ("# entries in session map"),
+                         GNUNET_CONTAINER_multihashmap_size (sessions),
+                         GNUNET_NO);
+  GSC_TYPEMAP_destroy (session->tmap);
+  session->tmap = NULL;
+  GNUNET_free (session);
+}
+
+
+/**
+ * Transmit our current typemap message to the other peer.
+ * (Done periodically in case an update got lost).
+ *
+ * @param cls the 'struct Session*'
+ * @param tc unused
+ */
+static void
+transmit_typemap_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+  struct Session *session = cls;
+  struct GNUNET_MessageHeader *hdr;
+  struct GNUNET_TIME_Relative delay;
+
+  delay = TYPEMAP_FREQUENCY;
+  /* randomize a bit to avoid spont. sync */
+  delay.rel_value +=
+      GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, 1000);
+  session->typemap_task =
+      GNUNET_SCHEDULER_add_delayed (delay, &transmit_typemap_task, session);
+  GNUNET_STATISTICS_update (GSC_stats,
+                            gettext_noop ("# type map refreshes sent"), 1,
+                            GNUNET_NO);
+  hdr = GSC_TYPEMAP_compute_type_map_message ();
+  GSC_KX_encrypt_and_transmit (session->kxinfo, hdr, ntohs (hdr->size));
+  GNUNET_free (hdr);
+}
+
+
+/**
+ * Create a session, a key exchange was just completed.
+ *
+ * @param peer peer that is now connected
+ * @param kx key exchange that completed
+ */
+void
+GSC_SESSIONS_create (const struct GNUNET_PeerIdentity *peer,
+                     struct GSC_KeyExchangeInfo *kx)
+{
+  struct Session *session;
+
+#if DEBUG_CORE
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Creating session for peer `%4s'\n",
+              GNUNET_i2s (peer));
+#endif
+  session = GNUNET_malloc (sizeof (struct Session));
+  session->tmap = GSC_TYPEMAP_create ();
+  session->peer = *peer;
+  session->kxinfo = kx;
+  session->time_established = GNUNET_TIME_absolute_get ();
+  session->typemap_task =
+      GNUNET_SCHEDULER_add_now (&transmit_typemap_task, session);
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CONTAINER_multihashmap_put (sessions, &peer->hashPubKey,
+                                                    session,
+                                                    GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
+  GNUNET_STATISTICS_set (GSC_stats, gettext_noop ("# entries in session map"),
+                         GNUNET_CONTAINER_multihashmap_size (sessions),
+                         GNUNET_NO);
+  GSC_CLIENTS_notify_clients_about_neighbour (peer, NULL, 0 /* FIXME: ATSI */ ,
+                                              NULL, session->tmap);
+}
+
+
+/**
+ * Notify the given client about the session (client is new).
+ *
+ * @param cls the 'struct GSC_Client'
+ * @param key peer identity
+ * @param value the 'struct Session'
+ * @return GNUNET_OK (continue to iterate)
+ */
+static int
+notify_client_about_session (void *cls, const GNUNET_HashCode * key,
+                             void *value)
+{
+  struct GSC_Client *client = cls;
+  struct Session *session = value;
+
+  GSC_CLIENTS_notify_client_about_neighbour (client, &session->peer, NULL, 0,   /* FIXME: ATS!? */
+                                             NULL,      /* old TMAP: none */
+                                             session->tmap);
+  return GNUNET_OK;
+}
+
+
+/**
+ * We have a new client, notify it about all current sessions.
+ *
+ * @param client the new client
+ */
+void
+GSC_SESSIONS_notify_client_about_sessions (struct GSC_Client *client)
+{
+  /* notify new client about existing sessions */
+  GNUNET_CONTAINER_multihashmap_iterate (sessions, &notify_client_about_session,
+                                         client);
+}
+
+
+/**
+ * Try to perform a transmission on the given session.  Will solicit
+ * additional messages if the 'sme' queue is not full enough.
+ *
+ * @param session session to transmit messages from
+ */
+static void
+try_transmission (struct Session *session);
+
+
+/**
+ * Queue a request from a client for transmission to a particular peer.
+ *
+ * @param car request to queue; this handle is then shared between
+ *         the caller (CLIENTS subsystem) and SESSIONS and must not
+ *         be released by either until either 'GNUNET_SESSIONS_dequeue',
+ *         'GNUNET_SESSIONS_transmit' or 'GNUNET_CLIENTS_failed'
+ *         have been invoked on it
+ */
+void
+GSC_SESSIONS_queue_request (struct GSC_ClientActiveRequest *car)
+{
+  struct Session *session;
+
+  session = find_session (&car->target);
+  if (session == NULL)
+  {
+#if DEBUG_CORE
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Dropped client request for transmission (am disconnected)\n");
+#endif
+    GNUNET_break (0);           /* should have been rejected earlier */
+    GSC_CLIENTS_reject_request (car);
+    return;
+  }
+  if (car->msize > GNUNET_CONSTANTS_MAX_ENCRYPTED_MESSAGE_SIZE)
+  {
+    GNUNET_break (0);
+    GSC_CLIENTS_reject_request (car);
+    return;
+  }
+#if DEBUG_CORE
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Received client transmission request. queueing\n");
+#endif
+  GNUNET_CONTAINER_DLL_insert (session->active_client_request_head,
+                               session->active_client_request_tail, car);
+  try_transmission (session);
+}
+
+
+/**
+ * Dequeue a request from a client from transmission to a particular peer.
+ *
+ * @param car request to dequeue; this handle will then be 'owned' by
+ *        the caller (CLIENTS sysbsystem)
+ */
+void
+GSC_SESSIONS_dequeue_request (struct GSC_ClientActiveRequest *car)
+{
+  struct Session *s;
+
+  if (0 ==
+      memcmp (&car->target, &GSC_my_identity,
+              sizeof (struct GNUNET_PeerIdentity)))
+    return;
+  s = find_session (&car->target);
+  GNUNET_assert (NULL != s);
+  GNUNET_CONTAINER_DLL_remove (s->active_client_request_head,
+                               s->active_client_request_tail, car);
+}
+
+
+/**
+ * Discard all expired active transmission requests from clients.
+ *
+ * @param session session to clean up
+ */
+static void
+discard_expired_requests (struct Session *session)
+{
+  struct GSC_ClientActiveRequest *pos;
+  struct GSC_ClientActiveRequest *nxt;
+  struct GNUNET_TIME_Absolute now;
+
+  now = GNUNET_TIME_absolute_get ();
+  pos = NULL;
+  nxt = session->active_client_request_head;
+  while (NULL != nxt)
+  {
+    pos = nxt;
+    nxt = pos->next;
+    if ((pos->deadline.abs_value < now.abs_value) &&
+        (GNUNET_YES != pos->was_solicited))
+    {
+      GNUNET_STATISTICS_update (GSC_stats,
+                                gettext_noop
+                                ("# messages discarded (expired prior to transmission)"),
+                                1, GNUNET_NO);
+      GNUNET_CONTAINER_DLL_remove (session->active_client_request_head,
+                                   session->active_client_request_tail, pos);
+      GSC_CLIENTS_reject_request (pos);
+    }
+  }
+}
+
+
+/**
+ * Solicit messages for transmission.
+ *
+ * @param session session to solict messages for
+ */
+static void
+solicit_messages (struct Session *session)
+{
+  struct GSC_ClientActiveRequest *car;
+  struct GSC_ClientActiveRequest *nxt;
+  size_t so_size;
+
+  discard_expired_requests (session);
+  so_size = 0;
+  nxt = session->active_client_request_head;
+  while (NULL != (car = nxt))
+  {
+    nxt = car->next;
+    if (so_size + car->msize > GNUNET_CONSTANTS_MAX_ENCRYPTED_MESSAGE_SIZE)
+      break;
+    so_size += car->msize;
+    if (car->was_solicited == GNUNET_YES)
+      continue;
+    car->was_solicited = GNUNET_YES;
+    GSC_CLIENTS_solicit_request (car);
+  }
+}
+
+
+/**
+ * Some messages were delayed (corked), but the timeout has now expired.
+ * Send them now.
+ *
+ * @param cls 'struct Session' with the messages to transmit now
+ * @param tc scheduler context (unused)
+ */
+static void
+pop_cork_task (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+  struct Session *session = cls;
+
+  session->cork_task = GNUNET_SCHEDULER_NO_TASK;
+  try_transmission (session);
+}
+
+
+/**
+ * Try to perform a transmission on the given session. Will solicit
+ * additional messages if the 'sme' queue is not full enough.
+ *
+ * @param session session to transmit messages from
+ */
+static void
+try_transmission (struct Session *session)
+{
+  struct SessionMessageEntry *pos;
+  size_t msize;
+  struct GNUNET_TIME_Absolute now;
+  struct GNUNET_TIME_Absolute min_deadline;
+
+  if (GNUNET_YES != session->ready_to_transmit)
+    return;
+  msize = 0;
+  min_deadline = GNUNET_TIME_UNIT_FOREVER_ABS;
+  /* check 'ready' messages */
+  pos = session->sme_head;
+  while ((NULL != pos) &&
+         (msize + pos->size <= GNUNET_CONSTANTS_MAX_ENCRYPTED_MESSAGE_SIZE))
+  {
+    GNUNET_assert (pos->size < GNUNET_CONSTANTS_MAX_ENCRYPTED_MESSAGE_SIZE);
+    msize += pos->size;
+    min_deadline = GNUNET_TIME_absolute_min (min_deadline, pos->deadline);
+    pos = pos->next;
+  }
+  now = GNUNET_TIME_absolute_get ();
+  if ((msize == 0) ||
+      ((msize < GNUNET_CONSTANTS_MAX_ENCRYPTED_MESSAGE_SIZE / 2) &&
+       (min_deadline.abs_value > now.abs_value)))
+  {
+    /* not enough ready yet, try to solicit more */
+    solicit_messages (session);
+    if (msize > 0)
+    {
+      /* if there is data to send, just not yet, make sure we do transmit
+       * it once the deadline is reached */
+      if (session->cork_task != GNUNET_SCHEDULER_NO_TASK)
+        GNUNET_SCHEDULER_cancel (session->cork_task);
+      session->cork_task =
+          GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_absolute_get_remaining
+                                        (min_deadline), &pop_cork_task,
+                                        session);
+    }
+    return;
+  }
+  /* create plaintext buffer of all messages, encrypt and transmit */
+  {
+    static unsigned long long total_bytes;
+    static unsigned int total_msgs;
+    char pbuf[msize];           /* plaintext */
+    size_t used;
+
+    used = 0;
+    while ((NULL != (pos = session->sme_head)) && (used + pos->size <= msize))
+    {
+      memcpy (&pbuf[used], &pos[1], pos->size);
+      used += pos->size;
+      GNUNET_CONTAINER_DLL_remove (session->sme_head, session->sme_tail, pos);
+      GNUNET_free (pos);
+    }
+    /* compute average payload size */
+    total_bytes += used;
+    total_msgs++;
+    if (0 == total_msgs)
+    {
+      /* 2^32 messages, wrap around... */
+      total_msgs = 1;
+      total_bytes = used;
+    }
+    GNUNET_STATISTICS_set (GSC_stats, "# avg payload per encrypted message",
+                           total_bytes / total_msgs, GNUNET_NO);
+    /* now actually transmit... */
+    session->ready_to_transmit = GNUNET_NO;
+    GSC_KX_encrypt_and_transmit (session->kxinfo, pbuf, used);
+  }
+}
+
+
+/**
+ * Send a message to the neighbour now.
+ *
+ * @param cls the message
+ * @param key neighbour's identity
+ * @param value 'struct Neighbour' of the target
+ * @return always GNUNET_OK
+ */
+static int
+do_send_message (void *cls, const GNUNET_HashCode * key, void *value)
+{
+  const struct GNUNET_MessageHeader *hdr = cls;
+  struct Session *session = value;
+  struct SessionMessageEntry *m;
+  uint16_t size;
+
+  size = ntohs (hdr->size);
+  m = GNUNET_malloc (sizeof (struct SessionMessageEntry) + size);
+  memcpy (&m[1], hdr, size);
+  m->size = size;
+  GNUNET_CONTAINER_DLL_insert (session->sme_head, session->sme_tail, m);
+  try_transmission (session);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Broadcast a message to all neighbours.
+ *
+ * @param msg message to transmit
+ */
+void
+GSC_SESSIONS_broadcast (const struct GNUNET_MessageHeader *msg)
+{
+  if (NULL == sessions)
+    return;
+  GNUNET_CONTAINER_multihashmap_iterate (sessions, &do_send_message,
+                                         (void *) msg);
+}
+
+
+/**
+ * Traffic is being solicited for the given peer.  This means that the
+ * message queue on the transport-level (NEIGHBOURS subsystem) is now
+ * empty and it is now OK to transmit another (non-control) message.
+ *
+ * @param pid identity of peer ready to receive data
+ */
+void
+GSC_SESSIONS_solicit (const struct GNUNET_PeerIdentity *pid)
+{
+  struct Session *session;
+
+  session = find_session (pid);
+  if (NULL == session)
+    return;
+  session->ready_to_transmit = GNUNET_YES;
+  try_transmission (session);
+}
+
+
+/**
+ * Transmit a message to a particular peer.
+ *
+ * @param car original request that was queued and then solicited;
+ *            this handle will now be 'owned' by the SESSIONS subsystem
+ * @param msg message to transmit
+ * @param cork is corking allowed?
+ */
+void
+GSC_SESSIONS_transmit (struct GSC_ClientActiveRequest *car,
+                       const struct GNUNET_MessageHeader *msg, int cork)
+{
+  struct Session *session;
+  struct SessionMessageEntry *sme;
+  size_t msize;
+
+  session = find_session (&car->target);
+  if (NULL == session)
+    return;
+  msize = ntohs (msg->size);
+  sme = GNUNET_malloc (sizeof (struct SessionMessageEntry) + msize);
+  memcpy (&sme[1], msg, msize);
+  sme->size = msize;
+  if (GNUNET_YES == cork)
+    sme->deadline =
+        GNUNET_TIME_relative_to_absolute (GNUNET_CONSTANTS_MAX_CORK_DELAY);
+  GNUNET_CONTAINER_DLL_insert_tail (session->sme_head, session->sme_tail, sme);
+  try_transmission (session);
+}
+
+
+/**
+ * Helper function for GSC_SESSIONS_handle_client_iterate_peers.
+ *
+ * @param cls the 'struct GNUNET_SERVER_TransmitContext' to queue replies
+ * @param key identity of the connected peer
+ * @param value the 'struct Neighbour' for the peer
+ * @return GNUNET_OK (continue to iterate)
+ */
+#include "core.h"
+static int
+queue_connect_message (void *cls, const GNUNET_HashCode * key, void *value)
+{
+  struct GNUNET_SERVER_TransmitContext *tc = cls;
+  struct Session *session = value;
+  struct ConnectNotifyMessage cnm;
+
+  /* FIXME: code duplication with clients... */
+  cnm.header.size = htons (sizeof (struct ConnectNotifyMessage));
+  cnm.header.type = htons (GNUNET_MESSAGE_TYPE_CORE_NOTIFY_CONNECT);
+  // FIXME: full ats...
+  cnm.ats_count = htonl (0);
+  cnm.peer = session->peer;
+  GNUNET_SERVER_transmit_context_append_message (tc, &cnm.header);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Handle CORE_ITERATE_PEERS request. For this request type, the client
+ * does not have to have transmitted an INIT request.  All current peers
+ * are returned, regardless of which message types they accept.
+ *
+ * @param cls unused
+ * @param client client sending the iteration request
+ * @param message iteration request message
+ */
+void
+GSC_SESSIONS_handle_client_iterate_peers (void *cls,
+                                          struct GNUNET_SERVER_Client *client,
+                                          const struct GNUNET_MessageHeader
+                                          *message)
+{
+  struct GNUNET_MessageHeader done_msg;
+  struct GNUNET_SERVER_TransmitContext *tc;
+
+  tc = GNUNET_SERVER_transmit_context_create (client);
+  GNUNET_CONTAINER_multihashmap_iterate (sessions, &queue_connect_message, tc);
+  done_msg.size = htons (sizeof (struct GNUNET_MessageHeader));
+  done_msg.type = htons (GNUNET_MESSAGE_TYPE_CORE_ITERATE_PEERS_END);
+  GNUNET_SERVER_transmit_context_append_message (tc, &done_msg);
+  GNUNET_SERVER_transmit_context_run (tc, GNUNET_TIME_UNIT_FOREVER_REL);
+}
+
+
+/**
+ * Handle CORE_PEER_CONNECTED request.   Notify client about connection
+ * to the given neighbour.  For this request type, the client does not
+ * have to have transmitted an INIT request.  All current peers are
+ * returned, regardless of which message types they accept.
+ *
+ * @param cls unused
+ * @param client client sending the iteration request
+ * @param message iteration request message
+ */
+void
+GSC_SESSIONS_handle_client_have_peer (void *cls,
+                                      struct GNUNET_SERVER_Client *client,
+                                      const struct GNUNET_MessageHeader
+                                      *message)
+{
+  struct GNUNET_MessageHeader done_msg;
+  struct GNUNET_SERVER_TransmitContext *tc;
+  const struct GNUNET_PeerIdentity *peer;
+
+  peer = (const struct GNUNET_PeerIdentity *) &message[1];      // YUCK!
+  tc = GNUNET_SERVER_transmit_context_create (client);
+  GNUNET_CONTAINER_multihashmap_get_multiple (sessions, &peer->hashPubKey,
+                                              &queue_connect_message, tc);
+  done_msg.size = htons (sizeof (struct GNUNET_MessageHeader));
+  done_msg.type = htons (GNUNET_MESSAGE_TYPE_CORE_ITERATE_PEERS_END);
+  GNUNET_SERVER_transmit_context_append_message (tc, &done_msg);
+  GNUNET_SERVER_transmit_context_run (tc, GNUNET_TIME_UNIT_FOREVER_REL);
+}
+
+
+/**
+ * We've received a typemap message from a peer, update ours.
+ * Notifies clients about the session.
+ *
+ * @param peer peer this is about
+ * @param msg typemap update message
+ */
+void
+GSC_SESSIONS_set_typemap (const struct GNUNET_PeerIdentity *peer,
+                          const struct GNUNET_MessageHeader *msg)
+{
+  struct Session *session;
+  struct GSC_TypeMap *nmap;
+
+  nmap = GSC_TYPEMAP_get_from_message (msg);
+  if (NULL == nmap)
+    return;                     /* malformed */
+  session = find_session (peer);
+  if (NULL == session)
+  {
+    GNUNET_break (0);
+    return;
+  }
+  GSC_CLIENTS_notify_clients_about_neighbour (peer, NULL, 0,    /* FIXME: ATS */
+                                              session->tmap, nmap);
+  GSC_TYPEMAP_destroy (session->tmap);
+  session->tmap = nmap;
+}
+
+
+/**
+ * The given peer send a message of the specified type.  Make sure the
+ * respective bit is set in its type-map and that clients are notified
+ * about the session.
+ *
+ * @param peer peer this is about
+ * @param type type of the message
+ */
+void
+GSC_SESSIONS_add_to_typemap (const struct GNUNET_PeerIdentity *peer,
+                             uint16_t type)
+{
+  struct Session *session;
+  struct GSC_TypeMap *nmap;
+
+  if (0 == memcmp (peer, &GSC_my_identity, sizeof (struct GNUNET_PeerIdentity)))
+    return;
+  session = find_session (peer);
+  GNUNET_assert (NULL != session);
+  if (GNUNET_YES == GSC_TYPEMAP_test_match (session->tmap, &type, 1))
+    return;                     /* already in it */
+  nmap = GSC_TYPEMAP_extend (session->tmap, &type, 1);
+  GSC_CLIENTS_notify_clients_about_neighbour (peer, NULL, 0,    /* FIXME: ATS */
+                                              session->tmap, nmap);
+  GSC_TYPEMAP_destroy (session->tmap);
+  session->tmap = nmap;
+}
+
+
+/**
+ * Initialize sessions subsystem.
+ */
+void
+GSC_SESSIONS_init ()
+{
+  sessions = GNUNET_CONTAINER_multihashmap_create (128);
+}
+
+
+/**
+ * Helper function for GSC_SESSIONS_handle_client_iterate_peers.
+ *
+ * @param cls NULL
+ * @param key identity of the connected peer
+ * @param value the 'struct Session' for the peer
+ * @return GNUNET_OK (continue to iterate)
+ */
+static int
+free_session_helper (void *cls, const GNUNET_HashCode * key, void *value)
+{
+  struct Session *session = value;
+
+  GSC_SESSIONS_end (&session->peer);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Shutdown sessions subsystem.
+ */
+void
+GSC_SESSIONS_done ()
+{
+  GNUNET_CONTAINER_multihashmap_iterate (sessions, &free_session_helper, NULL);
+  GNUNET_CONTAINER_multihashmap_destroy (sessions);
+  sessions = NULL;
+}
+
+/* end of gnunet-service-core_sessions.c */