1 files changed, 772 insertions, 0 deletions

diff --git a/src/service/core/core_api.c b/src/service/core/core_api.c
new file mode 100644
index 000000000..2e0bb1785
--- /dev/null
+++ b/src/service/core/core_api.c
@@ -0,0 +1,772 @@
+/*
+     This file is part of GNUnet.
+     Copyright (C) 2009-2016 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
+ */
+/**
+ * @file core/core_api.c
+ * @brief core service; this is the main API for encrypted P2P
+ *        communications
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "gnunet_util_lib.h"
+#include "gnunet_constants.h"
+#include "gnunet_core_service.h"
+#include "core.h"
+
+#define LOG(kind, ...) GNUNET_log_from (kind, "core-api", __VA_ARGS__)
+
+
+/**
+ * Information we track for each peer.
+ */
+struct PeerRecord
+{
+  /**
+   * Corresponding CORE handle.
+   */
+  struct GNUNET_CORE_Handle *h;
+
+  /**
+   * Message queue for the peer.
+   */
+  struct GNUNET_MQ_Handle *mq;
+
+  /**
+   * Message we are currently trying to pass to the CORE service
+   * for this peer (from @e mq).
+   */
+  struct GNUNET_MQ_Envelope *env;
+
+  /**
+   * Value the client returned when we connected, used
+   * as the closure in various places.
+   */
+  void *client_cls;
+
+  /**
+   * Peer the record is about.
+   */
+  struct GNUNET_PeerIdentity peer;
+
+  /**
+   * SendMessageRequest ID generator for this peer.
+   */
+  uint16_t smr_id_gen;
+};
+
+
+/**
+ * Context for the core service connection.
+ */
+struct GNUNET_CORE_Handle
+{
+  /**
+   * Configuration we're using.
+   */
+  const struct GNUNET_CONFIGURATION_Handle *cfg;
+
+  /**
+   * Closure for the various callbacks.
+   */
+  void *cls;
+
+  /**
+   * Function to call once we've handshaked with the core service.
+   */
+  GNUNET_CORE_StartupCallback init;
+
+  /**
+   * Function to call whenever we're notified about a peer connecting.
+   */
+  GNUNET_CORE_ConnectEventHandler connects;
+
+  /**
+   * Function to call whenever we're notified about a peer disconnecting.
+   */
+  GNUNET_CORE_DisconnectEventHandler disconnects;
+
+  /**
+   * Function handlers for messages of particular type.
+   */
+  struct GNUNET_MQ_MessageHandler *handlers;
+
+  /**
+   * Our message queue for transmissions to the service.
+   */
+  struct GNUNET_MQ_Handle *mq;
+
+  /**
+   * Hash map listing all of the peers that we are currently
+   * connected to.
+   */
+  struct GNUNET_CONTAINER_MultiPeerMap *peers;
+
+  /**
+   * Identity of this peer.
+   */
+  struct GNUNET_PeerIdentity me;
+
+  /**
+   * ID of reconnect task (if any).
+   */
+  struct GNUNET_SCHEDULER_Task *reconnect_task;
+
+  /**
+   * Current delay we use for re-trying to connect to core.
+   */
+  struct GNUNET_TIME_Relative retry_backoff;
+
+  /**
+   * Number of entries in the handlers array.
+   */
+  unsigned int hcnt;
+
+  /**
+   * Did we ever get INIT?
+   */
+  int have_init;
+};
+
+
+/**
+ * Our current client connection went down.  Clean it up
+ * and try to reconnect!
+ *
+ * @param h our handle to the core service
+ */
+static void
+reconnect (struct GNUNET_CORE_Handle *h);
+
+
+/**
+ * Task schedule to try to re-connect to core.
+ *
+ * @param cls the `struct GNUNET_CORE_Handle`
+ */
+static void
+reconnect_task (void *cls)
+{
+  struct GNUNET_CORE_Handle *h = cls;
+
+  h->reconnect_task = NULL;
+  LOG (GNUNET_ERROR_TYPE_DEBUG, "Connecting to CORE service after delay\n");
+  reconnect (h);
+}
+
+
+/**
+ * Notify clients about disconnect and free the entry for connected
+ * peer.
+ *
+ * @param cls the `struct GNUNET_CORE_Handle *`
+ * @param key the peer identity (not used)
+ * @param value the `struct PeerRecord` to free.
+ * @return #GNUNET_YES (continue)
+ */
+static int
+disconnect_and_free_peer_entry (void *cls,
+                                const struct GNUNET_PeerIdentity *key,
+                                void *value)
+{
+  struct GNUNET_CORE_Handle *h = cls;
+  struct PeerRecord *pr = value;
+
+  GNUNET_assert (pr->h == h);
+  if (NULL != h->disconnects)
+    h->disconnects (h->cls, &pr->peer, pr->client_cls);
+  GNUNET_assert (GNUNET_YES ==
+                 GNUNET_CONTAINER_multipeermap_remove (h->peers, key, pr));
+  GNUNET_MQ_destroy (pr->mq);
+  GNUNET_assert (NULL == pr->mq);
+  if (NULL != pr->env)
+  {
+    GNUNET_MQ_discard (pr->env);
+    pr->env = NULL;
+  }
+  GNUNET_free (pr);
+  return GNUNET_YES;
+}
+
+
+/**
+ * Close down any existing connection to the CORE service and
+ * try re-establishing it later.
+ *
+ * @param h our handle
+ */
+static void
+reconnect_later (struct GNUNET_CORE_Handle *h)
+{
+  GNUNET_assert (NULL == h->reconnect_task);
+  if (NULL != h->mq)
+  {
+    GNUNET_MQ_destroy (h->mq);
+    h->mq = NULL;
+  }
+  GNUNET_assert (NULL == h->reconnect_task);
+  h->reconnect_task =
+    GNUNET_SCHEDULER_add_delayed (h->retry_backoff, &reconnect_task, h);
+  GNUNET_CONTAINER_multipeermap_iterate (h->peers,
+                                         &disconnect_and_free_peer_entry,
+                                         h);
+  h->retry_backoff = GNUNET_TIME_STD_BACKOFF (h->retry_backoff);
+}
+
+
+/**
+ * Error handler for the message queue to the CORE service.
+ * On errors, we reconnect.
+ *
+ * @param cls closure, a `struct GNUNET_CORE_Handle *`
+ * @param error error code
+ */
+static void
+handle_mq_error (void *cls, enum GNUNET_MQ_Error error)
+{
+  struct GNUNET_CORE_Handle *h = cls;
+
+  LOG (GNUNET_ERROR_TYPE_DEBUG, "MQ ERROR: %d\n", error);
+  reconnect_later (h);
+}
+
+
+/**
+ * Implement sending functionality of a message queue for
+ * us sending messages to a peer.
+ *
+ * @param mq the message queue
+ * @param msg the message to send
+ * @param impl_state state of the implementation
+ */
+static void
+core_mq_send_impl (struct GNUNET_MQ_Handle *mq,
+                   const struct GNUNET_MessageHeader *msg,
+                   void *impl_state)
+{
+  struct PeerRecord *pr = impl_state;
+  struct GNUNET_CORE_Handle *h = pr->h;
+  struct SendMessageRequest *smr;
+  struct SendMessage *sm;
+  struct GNUNET_MQ_Envelope *env;
+  uint16_t msize;
+  enum GNUNET_MQ_PriorityPreferences flags;
+
+  if (NULL == h->mq)
+  {
+    /* We're currently reconnecting, pretend this worked */
+    GNUNET_MQ_impl_send_continue (mq);
+    return;
+  }
+  GNUNET_assert (NULL == pr->env);
+  /* extract options from envelope */
+  env = GNUNET_MQ_get_current_envelope (mq);
+  flags = GNUNET_MQ_env_get_options (env);
+
+  /* check message size for sanity */
+  msize = ntohs (msg->size);
+  if (msize >= GNUNET_MAX_MESSAGE_SIZE - sizeof(struct SendMessage))
+  {
+    GNUNET_break (0);
+    GNUNET_MQ_impl_send_continue (mq);
+    return;
+  }
+
+  /* ask core for transmission */
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Asking core for transmission of %u bytes to `%s'\n",
+       (unsigned int) msize,
+       GNUNET_i2s (&pr->peer));
+  env = GNUNET_MQ_msg (smr, GNUNET_MESSAGE_TYPE_CORE_SEND_REQUEST);
+  smr->priority = htonl ((uint32_t) flags);
+  smr->peer = pr->peer;
+  smr->size = htons (msize);
+  smr->smr_id = htons (++pr->smr_id_gen);
+  GNUNET_MQ_send (h->mq, env);
+
+  /* prepare message with actual transmission data */
+  pr->env = GNUNET_MQ_msg_nested_mh (sm, GNUNET_MESSAGE_TYPE_CORE_SEND, msg);
+  sm->priority = htonl ((uint32_t) flags);
+  sm->peer = pr->peer;
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Calling get_message with buffer of %u bytes\n",
+       (unsigned int) msize);
+}
+
+
+/**
+ * Handle destruction of a message queue.  Implementations must not
+ * free @a mq, but should take care of @a impl_state.
+ *
+ * @param mq the message queue to destroy
+ * @param impl_state state of the implementation
+ */
+static void
+core_mq_destroy_impl (struct GNUNET_MQ_Handle *mq, void *impl_state)
+{
+  struct PeerRecord *pr = impl_state;
+
+  GNUNET_assert (mq == pr->mq);
+  pr->mq = NULL;
+}
+
+
+/**
+ * Implementation function that cancels the currently sent message.
+ * Should basically undo whatever #mq_send_impl() did.
+ *
+ * @param mq message queue
+ * @param impl_state state specific to the implementation
+ */
+static void
+core_mq_cancel_impl (struct GNUNET_MQ_Handle *mq, void *impl_state)
+{
+  struct PeerRecord *pr = impl_state;
+
+  (void) mq;
+  GNUNET_assert (NULL != pr->env);
+  GNUNET_MQ_discard (pr->env);
+  pr->env = NULL;
+}
+
+
+/**
+ * We had an error processing a message we forwarded from a peer to
+ * the CORE service.  We should just complain about it but otherwise
+ * continue processing.
+ *
+ * @param cls closure
+ * @param error error code
+ */
+static void
+core_mq_error_handler (void *cls, enum GNUNET_MQ_Error error)
+{
+  /* struct PeerRecord *pr = cls; */
+  (void) cls;
+  (void) error;
+  GNUNET_break_op (0);
+}
+
+
+/**
+ * Add the given peer to the list of our connected peers
+ * and create the respective data structures and notify
+ * the application.
+ *
+ * @param h the core handle
+ * @param peer the peer that is connecting to us
+ */
+static void
+connect_peer (struct GNUNET_CORE_Handle *h,
+              const struct GNUNET_PeerIdentity *peer)
+{
+  struct PeerRecord *pr;
+
+  pr = GNUNET_new (struct PeerRecord);
+  pr->peer = *peer;
+  pr->h = h;
+  GNUNET_assert (GNUNET_YES ==
+                 GNUNET_CONTAINER_multipeermap_put (
+                   h->peers,
+                   &pr->peer,
+                   pr,
+                   GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
+  pr->mq = GNUNET_MQ_queue_for_callbacks (&core_mq_send_impl,
+                                          &core_mq_destroy_impl,
+                                          &core_mq_cancel_impl,
+                                          pr,
+                                          h->handlers,
+                                          &core_mq_error_handler,
+                                          pr);
+  if (NULL != h->connects)
+  {
+    pr->client_cls = h->connects (h->cls, &pr->peer, pr->mq);
+    GNUNET_MQ_set_handlers_closure (pr->mq, pr->client_cls);
+  }
+}
+
+
+/**
+ * Handle  init  reply message  received  from  CORE service.   Notify
+ * application  that we  are now  connected  to the  CORE.  Also  fake
+ * loopback connection.
+ *
+ * @param cls the `struct GNUNET_CORE_Handle`
+ * @param m the init reply
+ */
+static void
+handle_init_reply (void *cls, const struct InitReplyMessage *m)
+{
+  struct GNUNET_CORE_Handle *h = cls;
+  GNUNET_CORE_StartupCallback init;
+
+  GNUNET_break (0 == ntohl (m->reserved));
+  h->retry_backoff = GNUNET_TIME_UNIT_MILLISECONDS;
+  if (NULL != (init = h->init))
+  {
+    /* mark so we don't call init on reconnect */
+    h->init = NULL;
+    h->me = m->my_identity;
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Connected to core service of peer `%s'.\n",
+         GNUNET_i2s (&h->me));
+    h->have_init = GNUNET_YES;
+    init (h->cls, &h->me);
+  }
+  else
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Successfully reconnected to core service.\n");
+    if (GNUNET_NO == h->have_init)
+    {
+      h->me = m->my_identity;
+      h->have_init = GNUNET_YES;
+    }
+    else
+    {
+      GNUNET_break (0 == memcmp (&h->me,
+                                 &m->my_identity,
+                                 sizeof(struct GNUNET_PeerIdentity)));
+    }
+  }
+  /* fake 'connect to self' */
+  connect_peer (h, &h->me);
+}
+
+
+/**
+ * Handle connect message received from CORE service.
+ * Notify the application about the new connection.
+ *
+ * @param cls the `struct GNUNET_CORE_Handle`
+ * @param cnm the connect message
+ */
+static void
+handle_connect_notify (void *cls, const struct ConnectNotifyMessage *cnm)
+{
+  struct GNUNET_CORE_Handle *h = cls;
+  struct PeerRecord *pr;
+
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received notification about connection from `%s'.\n",
+       GNUNET_i2s (&cnm->peer));
+  if (0 == memcmp (&h->me, &cnm->peer, sizeof(struct GNUNET_PeerIdentity)))
+  {
+    /* connect to self!? */
+    GNUNET_break (0);
+    return;
+  }
+  pr = GNUNET_CONTAINER_multipeermap_get (h->peers, &cnm->peer);
+  if (NULL != pr)
+  {
+    GNUNET_break (0);
+    reconnect_later (h);
+    return;
+  }
+  connect_peer (h, &cnm->peer);
+}
+
+
+/**
+ * Handle disconnect message received from CORE service.
+ * Notify the application about the lost connection.
+ *
+ * @param cls the `struct GNUNET_CORE_Handle`
+ * @param dnm message about the disconnect event
+ */
+static void
+handle_disconnect_notify (void *cls, const struct DisconnectNotifyMessage *dnm)
+{
+  struct GNUNET_CORE_Handle *h = cls;
+  struct PeerRecord *pr;
+
+  if (0 == memcmp (&h->me, &dnm->peer, sizeof(struct GNUNET_PeerIdentity)))
+  {
+    /* disconnect from self!? */
+    GNUNET_break (0);
+    return;
+  }
+  GNUNET_break (0 == ntohl (dnm->reserved));
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received notification about disconnect from `%s'.\n",
+       GNUNET_i2s (&dnm->peer));
+  pr = GNUNET_CONTAINER_multipeermap_get (h->peers, &dnm->peer);
+  if (NULL == pr)
+  {
+    GNUNET_break (0);
+    reconnect_later (h);
+    return;
+  }
+  disconnect_and_free_peer_entry (h, &pr->peer, pr);
+}
+
+
+/**
+ * Check that message received from CORE service is well-formed.
+ *
+ * @param cls the `struct GNUNET_CORE_Handle`
+ * @param ntm the message we got
+ * @return #GNUNET_OK if the message is well-formed
+ */
+static int
+check_notify_inbound (void *cls, const struct NotifyTrafficMessage *ntm)
+{
+  uint16_t msize;
+  const struct GNUNET_MessageHeader *em;
+
+  (void) cls;
+  msize = ntohs (ntm->header.size) - sizeof(struct NotifyTrafficMessage);
+  if (msize < sizeof(struct GNUNET_MessageHeader))
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  em = (const struct GNUNET_MessageHeader *) &ntm[1];
+  if (msize != ntohs (em->size))
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
+}
+
+
+/**
+ * Handle inbound message received from CORE service.  If applicable,
+ * notify the application.
+ *
+ * @param cls the `struct GNUNET_CORE_Handle`
+ * @param ntm the message we got from CORE.
+ */
+static void
+handle_notify_inbound (void *cls, const struct NotifyTrafficMessage *ntm)
+{
+  struct GNUNET_CORE_Handle *h = cls;
+  const struct GNUNET_MessageHeader *em;
+  struct PeerRecord *pr;
+
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received inbound message from `%s'.\n",
+       GNUNET_i2s (&ntm->peer));
+  em = (const struct GNUNET_MessageHeader *) &ntm[1];
+  pr = GNUNET_CONTAINER_multipeermap_get (h->peers, &ntm->peer);
+  if (NULL == pr)
+  {
+    GNUNET_break (0);
+    reconnect_later (h);
+    return;
+  }
+  GNUNET_MQ_inject_message (pr->mq, em);
+}
+
+
+/**
+ * Handle message received from CORE service notifying us that we are
+ * now allowed to send a message to a peer.  If that message is still
+ * pending, put it into the queue to be transmitted.
+ *
+ * @param cls the `struct GNUNET_CORE_Handle`
+ * @param smr the message we got
+ */
+static void
+handle_send_ready (void *cls, const struct SendMessageReady *smr)
+{
+  struct GNUNET_CORE_Handle *h = cls;
+  struct PeerRecord *pr;
+
+  pr = GNUNET_CONTAINER_multipeermap_get (h->peers, &smr->peer);
+  if (NULL == pr)
+  {
+    GNUNET_break (0);
+    reconnect_later (h);
+    return;
+  }
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received notification about transmission readiness to `%s'.\n",
+       GNUNET_i2s (&smr->peer));
+  if (NULL == pr->env)
+  {
+    /* request must have been cancelled between the original request
+     * and the response from CORE, ignore CORE's readiness */
+    return;
+  }
+  if (ntohs (smr->smr_id) != pr->smr_id_gen)
+  {
+    /* READY message is for expired or cancelled message,
+     * ignore! (we should have already sent another request) */
+    return;
+  }
+
+  /* ok, all good, send message out! */
+  GNUNET_MQ_send (h->mq, pr->env);
+  pr->env = NULL;
+  GNUNET_MQ_impl_send_continue (pr->mq);
+}
+
+
+/**
+ * Our current client connection went down.  Clean it up and try to
+ * reconnect!
+ *
+ * @param h our handle to the core service
+ */
+static void
+reconnect (struct GNUNET_CORE_Handle *h)
+{
+  struct GNUNET_MQ_MessageHandler handlers[] =
+  { GNUNET_MQ_hd_fixed_size (init_reply,
+                             GNUNET_MESSAGE_TYPE_CORE_INIT_REPLY,
+                             struct InitReplyMessage,
+                             h),
+    GNUNET_MQ_hd_fixed_size (connect_notify,
+                             GNUNET_MESSAGE_TYPE_CORE_NOTIFY_CONNECT,
+                             struct ConnectNotifyMessage,
+                             h),
+    GNUNET_MQ_hd_fixed_size (disconnect_notify,
+                             GNUNET_MESSAGE_TYPE_CORE_NOTIFY_DISCONNECT,
+                             struct DisconnectNotifyMessage,
+                             h),
+    GNUNET_MQ_hd_var_size (notify_inbound,
+                           GNUNET_MESSAGE_TYPE_CORE_NOTIFY_INBOUND,
+                           struct NotifyTrafficMessage,
+                           h),
+    GNUNET_MQ_hd_fixed_size (send_ready,
+                             GNUNET_MESSAGE_TYPE_CORE_SEND_READY,
+                             struct SendMessageReady,
+                             h),
+    GNUNET_MQ_handler_end () };
+  struct InitMessage *init;
+  struct GNUNET_MQ_Envelope *env;
+  uint16_t *ts;
+
+  GNUNET_assert (NULL == h->mq);
+  h->mq = GNUNET_CLIENT_connect (h->cfg, "core", handlers, &handle_mq_error, h);
+  if (NULL == h->mq)
+  {
+    reconnect_later (h);
+    return;
+  }
+  env = GNUNET_MQ_msg_extra (init,
+                             sizeof(uint16_t) * h->hcnt,
+                             GNUNET_MESSAGE_TYPE_CORE_INIT);
+  LOG (GNUNET_ERROR_TYPE_INFO, "(Re)connecting to CORE service\n");
+  init->options = htonl (0);
+  ts = (uint16_t *) &init[1];
+  for (unsigned int hpos = 0; hpos < h->hcnt; hpos++)
+    ts[hpos] = htons (h->handlers[hpos].type);
+  GNUNET_MQ_send (h->mq, env);
+}
+
+
+/**
+ * Connect to the core service.  Note that the connection may complete
+ * (or fail) asynchronously.
+ *
+ * @param cfg configuration to use
+ * @param cls closure for the various callbacks that follow (including handlers in the handlers array)
+ * @param init callback to call once we have successfully
+ *        connected to the core service
+ * @param connects function to call on peer connect, can be NULL
+ * @param disconnects function to call on peer disconnect / timeout, can be NULL
+ * @param handlers callbacks for messages we care about, NULL-terminated
+ * @return handle to the core service (only useful for disconnect until @a init is called);
+ *                NULL on error (in this case, init is never called)
+ */
+struct GNUNET_CORE_Handle *
+GNUNET_CORE_connect (const struct GNUNET_CONFIGURATION_Handle *cfg,
+                     void *cls,
+                     GNUNET_CORE_StartupCallback init,
+                     GNUNET_CORE_ConnectEventHandler connects,
+                     GNUNET_CORE_DisconnectEventHandler disconnects,
+                     const struct GNUNET_MQ_MessageHandler *handlers)
+{
+  struct GNUNET_CORE_Handle *h;
+
+  h = GNUNET_new (struct GNUNET_CORE_Handle);
+  h->cfg = cfg;
+  h->cls = cls;
+  h->init = init;
+  h->connects = connects;
+  h->disconnects = disconnects;
+  h->peers = GNUNET_CONTAINER_multipeermap_create (128, GNUNET_NO);
+  h->handlers = GNUNET_MQ_copy_handlers (handlers);
+  h->hcnt = GNUNET_MQ_count_handlers (handlers);
+  GNUNET_assert (h->hcnt <
+                 (GNUNET_MAX_MESSAGE_SIZE - sizeof(struct InitMessage))
+                 / sizeof(uint16_t));
+  LOG (GNUNET_ERROR_TYPE_DEBUG, "Connecting to CORE service\n");
+  reconnect (h);
+  if (NULL == h->mq)
+  {
+    GNUNET_CORE_disconnect (h);
+    return NULL;
+  }
+  return h;
+}
+
+
+/**
+ * Disconnect from the core service.
+ *
+ * @param handle connection to core to disconnect
+ */
+void
+GNUNET_CORE_disconnect (struct GNUNET_CORE_Handle *handle)
+{
+  LOG (GNUNET_ERROR_TYPE_DEBUG, "Disconnecting from CORE service\n");
+  GNUNET_CONTAINER_multipeermap_iterate (handle->peers,
+                                         &disconnect_and_free_peer_entry,
+                                         handle);
+  GNUNET_CONTAINER_multipeermap_destroy (handle->peers);
+  handle->peers = NULL;
+  if (NULL != handle->reconnect_task)
+  {
+    GNUNET_SCHEDULER_cancel (handle->reconnect_task);
+    handle->reconnect_task = NULL;
+  }
+  if (NULL != handle->mq)
+  {
+    GNUNET_MQ_destroy (handle->mq);
+    handle->mq = NULL;
+  }
+  GNUNET_free (handle->handlers);
+  GNUNET_free (handle);
+}
+
+
+/**
+ * Obtain the message queue for a connected peer.
+ *
+ * @param h the core handle
+ * @param pid the identity of the peer to check if it has been connected to us
+ * @return NULL if peer is not connected
+ */
+struct GNUNET_MQ_Handle *
+GNUNET_CORE_get_mq (const struct GNUNET_CORE_Handle *h,
+                    const struct GNUNET_PeerIdentity *pid)
+{
+  struct PeerRecord *pr;
+
+  pr = GNUNET_CONTAINER_multipeermap_get (h->peers, pid);
+  if (NULL == pr)
+    return NULL;
+  return pr->mq;
+}
+
+
+/* end of core_api.c */