1 files changed, 1706 insertions, 0 deletions

diff --git a/src/cadet/cadet_api.c b/src/cadet/cadet_api.c
new file mode 100644
index 000000000..c9f2a11bb
--- /dev/null
+++ b/src/cadet/cadet_api.c
@@ -0,0 +1,1706 @@
+/*
+     This file is part of GNUnet.
+     Copyright (C) 2011, 2017 GNUnet e.V.
+
+     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., 51 Franklin Street, Fifth Floor,
+     Boston, MA 02110-1301, USA.
+*/
+/**
+ * @file cadet/cadet_api.c
+ * @brief cadet api: client implementation of cadet service
+ * @author Bartlomiej Polot
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "gnunet_util_lib.h"
+#include "gnunet_constants.h"
+#include "gnunet_cadet_service.h"
+#include "cadet.h"
+#include "cadet_protocol.h"
+
+#define LOG(kind,...) GNUNET_log_from (kind, "cadet-api",__VA_ARGS__)
+
+/**
+ * Ugly legacy hack.
+ */
+union CadetInfoCB
+{
+
+  /**
+   * Channel callback.
+   */
+  GNUNET_CADET_ChannelCB channel_cb;
+
+  /**
+   * Monitor callback
+   */
+  GNUNET_CADET_PeersCB peers_cb;
+
+  /**
+   * Monitor callback
+   */
+  GNUNET_CADET_PeerCB peer_cb;
+
+  /**
+   * Monitor callback
+   */
+  GNUNET_CADET_TunnelsCB tunnels_cb;
+
+  /**
+   * Tunnel callback.
+   */
+  GNUNET_CADET_TunnelCB tunnel_cb;
+};
+
+
+/**
+ * Opaque handle to the service.
+ */
+struct GNUNET_CADET_Handle
+{
+  /**
+   * Message queue.
+   */
+  struct GNUNET_MQ_Handle *mq;
+
+  /**
+   * Ports open.
+   */
+  struct GNUNET_CONTAINER_MultiHashMap *ports;
+
+  /**
+   * Channels open.
+   */
+  struct GNUNET_CONTAINER_MultiHashMap32 *channels;
+
+  /**
+   * child of the next channel to create (to avoid reusing IDs often)
+   */
+  struct GNUNET_CADET_ClientChannelNumber next_ccn;
+
+  /**
+   * Configuration given by the client, in case of reconnection
+   */
+  const struct GNUNET_CONFIGURATION_Handle *cfg;
+
+  /**
+   * Task for trying to reconnect.
+   */
+  struct GNUNET_SCHEDULER_Task *reconnect_task;
+
+  /**
+   * Callback for an info task (only one active at a time).
+   */
+  union CadetInfoCB info_cb;
+
+  /**
+   * Info callback closure for @c info_cb.
+   */
+  void *info_cls;
+
+  /**
+   * Time to the next reconnect in case one reconnect fails
+   */
+  struct GNUNET_TIME_Relative reconnect_time;
+
+};
+
+
+/**
+ * Opaque handle to a channel.
+ */
+struct GNUNET_CADET_Channel
+{
+
+  /**
+   * Other end of the channel.
+   */
+  struct GNUNET_PeerIdentity peer;
+
+  /**
+   * Handle to the cadet this channel belongs to
+   */
+  struct GNUNET_CADET_Handle *cadet;
+
+  /**
+   * Channel's port, if incoming.
+   */
+  struct GNUNET_CADET_Port *incoming_port;
+
+  /**
+   * Any data the caller wants to put in here, used for the
+   * various callbacks (@e disconnects, @e window_changes, handlers).
+   */
+  void *ctx;
+
+  /**
+   * Message Queue for the channel (which we are implementing).
+   */
+  struct GNUNET_MQ_Handle *mq;
+
+  /**
+   * Task to allow mq to send more traffic.
+   */
+  struct GNUNET_SCHEDULER_Task *mq_cont;
+
+  /**
+   * Pending envelope with a message to be transmitted to the
+   * service as soon as we are allowed to.  Should only be
+   * non-NULL if @e allow_send is 0.
+   */
+  struct GNUNET_MQ_Envelope *pending_env;
+
+  /**
+   * Window change handler.
+   */
+  GNUNET_CADET_WindowSizeEventHandler window_changes;
+
+  /**
+   * Disconnect handler.
+   */
+  GNUNET_CADET_DisconnectEventHandler disconnects;
+
+  /**
+   * Local ID of the channel, #GNUNET_CADET_LOCAL_CHANNEL_ID_CLI bit is set if outbound.
+   */
+  struct GNUNET_CADET_ClientChannelNumber ccn;
+
+  /**
+   * Channel options: reliability, etc.
+   */
+  enum GNUNET_CADET_ChannelOption options;
+
+  /**
+   * How many messages are we allowed to send to the service right now?
+   */
+  unsigned int allow_send;
+
+};
+
+
+/**
+ * Opaque handle to a port.
+ */
+struct GNUNET_CADET_Port
+{
+
+  /**
+   * Port "number"
+   */
+  struct GNUNET_HashCode id;
+
+  /**
+   * Handle to the CADET session this port belongs to.
+   */
+  struct GNUNET_CADET_Handle *cadet;
+
+  /**
+   * Closure for @a handler.
+   */
+  void *cls;
+
+  /**
+   * Handler for incoming channels on this port
+   */
+  GNUNET_CADET_ConnectEventHandler connects;
+
+  /**
+   * Closure for @ref connects
+   */
+  void *connects_cls;
+
+  /**
+   * Window size change handler.
+   */
+  GNUNET_CADET_WindowSizeEventHandler window_changes;
+
+  /**
+   * Handler called when an incoming channel is destroyed.
+   */
+  GNUNET_CADET_DisconnectEventHandler disconnects;
+
+  /**
+   * Payload handlers for incoming channels.
+   */
+  struct GNUNET_MQ_MessageHandler *handlers;
+};
+
+
+/**
+ * Find the Port struct for a hash.
+ *
+ * @param h CADET handle.
+ * @param hash HashCode for the port number.
+ * @return The port handle if known, NULL otherwise.
+ */
+static struct GNUNET_CADET_Port *
+find_port (const struct GNUNET_CADET_Handle *h,
+           const struct GNUNET_HashCode *hash)
+{
+  return GNUNET_CONTAINER_multihashmap_get (h->ports,
+                                            hash);
+}
+
+
+/**
+ * Get the channel handler for the channel specified by id from the given handle
+ *
+ * @param h Cadet handle
+ * @param ccn ID of the wanted channel
+ * @return handle to the required channel or NULL if not found
+ */
+static struct GNUNET_CADET_Channel *
+find_channel (struct GNUNET_CADET_Handle *h,
+              struct GNUNET_CADET_ClientChannelNumber ccn)
+{
+  return GNUNET_CONTAINER_multihashmap32_get (h->channels,
+                                              ntohl (ccn.channel_of_client));
+}
+
+
+/**
+ * Create a new channel and insert it in the channel list of the cadet handle
+ *
+ * @param h Cadet handle
+ * @param ccnp pointer to desired ccn of the channel, NULL to assign one automatically.
+ * @return Handle to the created channel.
+ */
+static struct GNUNET_CADET_Channel *
+create_channel (struct GNUNET_CADET_Handle *h,
+                const struct GNUNET_CADET_ClientChannelNumber *ccnp)
+{
+  struct GNUNET_CADET_Channel *ch;
+  struct GNUNET_CADET_ClientChannelNumber ccn;
+
+  ch = GNUNET_new (struct GNUNET_CADET_Channel);
+  ch->cadet = h;
+  if (NULL == ccnp)
+  {
+    while (NULL !=
+           find_channel (h,
+                         h->next_ccn))
+      h->next_ccn.channel_of_client
+        = htonl (GNUNET_CADET_LOCAL_CHANNEL_ID_CLI | (1 + ntohl (h->next_ccn.channel_of_client)));
+    ccn = h->next_ccn;
+  }
+  else
+  {
+    ccn = *ccnp;
+  }
+  ch->ccn = ccn;
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CONTAINER_multihashmap32_put (h->channels,
+                                                      ntohl (ch->ccn.channel_of_client),
+                                                      ch,
+                                                      GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
+  return ch;
+}
+
+
+/**
+ * Destroy the specified channel.
+ * - Destroys all peers, calling the disconnect callback on each if needed
+ * - Cancels all outgoing traffic for that channel, calling respective notifys
+ * - Calls cleaner if channel was inbound
+ * - Frees all memory used
+ *
+ * @param ch Pointer to the channel.
+ * @param call_cleaner Whether to call the cleaner handler.
+ */
+static void
+destroy_channel (struct GNUNET_CADET_Channel *ch)
+{
+  struct GNUNET_CADET_Handle *h = ch->cadet;
+
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Destroying channel %X of %p\n",
+       ch->ccn,
+       h);
+  GNUNET_assert (GNUNET_YES ==
+                 GNUNET_CONTAINER_multihashmap32_remove (h->channels,
+                                                         ntohl (ch->ccn.channel_of_client),
+                                                         ch));
+  if (NULL != ch->mq_cont)
+  {
+    GNUNET_SCHEDULER_cancel (ch->mq_cont);
+    ch->mq_cont = NULL;
+  }
+  /* signal channel destruction */
+  if (NULL != ch->disconnects)
+    ch->disconnects (ch->ctx,
+                     ch);
+  if (NULL != ch->pending_env)
+    GNUNET_MQ_discard (ch->pending_env);
+  GNUNET_MQ_destroy (ch->mq);
+  GNUNET_free (ch);
+}
+
+
+/**
+ * Reconnect to the service, retransmit all infomation to try to restore the
+ * original state.
+ *
+ * @param h handle to the cadet
+ */
+static void
+reconnect (struct GNUNET_CADET_Handle *h);
+
+
+/**
+ * Reconnect callback: tries to reconnect again after a failer previous
+ * reconnecttion
+ *
+ * @param cls closure (cadet handle)
+ */
+static void
+reconnect_cbk (void *cls)
+{
+  struct GNUNET_CADET_Handle *h = cls;
+
+  h->reconnect_task = NULL;
+  reconnect (h);
+}
+
+
+/**
+ * Function called during #reconnect() to destroy
+ * all channels that are still open.
+ *
+ * @param cls the `struct GNUNET_CADET_Handle`
+ * @param cid chanenl ID
+ * @param value a `struct GNUNET_CADET_Channel` to destroy
+ * @return #GNUNET_OK (continue to iterate)
+ */
+static int
+destroy_channel_on_reconnect_cb (void *cls,
+                                 uint32_t cid,
+                                 void *value)
+{
+  /* struct GNUNET_CADET_Handle *handle = cls; */
+  struct GNUNET_CADET_Channel *ch = value;
+
+  destroy_channel (ch);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Reconnect to the service, retransmit all infomation to try to restore the
+ * original state.
+ *
+ * @param h handle to the cadet
+ *
+ * @return #GNUNET_YES in case of sucess, #GNUNET_NO otherwise (service down...)
+ */
+static void
+schedule_reconnect (struct GNUNET_CADET_Handle *h)
+{
+  if (NULL != h->reconnect_task)
+    return;
+  GNUNET_CONTAINER_multihashmap32_iterate (h->channels,
+                                           &destroy_channel_on_reconnect_cb,
+                                           h);
+  h->reconnect_task
+    = GNUNET_SCHEDULER_add_delayed (h->reconnect_time,
+                                    &reconnect_cbk,
+                                    h);
+  h->reconnect_time
+    = GNUNET_TIME_STD_BACKOFF (h->reconnect_time);
+}
+
+
+/**
+ * Notify the application about a change in the window size (if needed).
+ *
+ * @param ch Channel to notify about.
+ */
+static void
+notify_window_size (struct GNUNET_CADET_Channel *ch)
+{
+  if (NULL != ch->window_changes)
+    ch->window_changes (ch->ctx,
+                        ch, /* FIXME: remove 'ch'? */
+                        ch->allow_send);
+}
+
+
+/**
+ * Transmit the next message from our queue.
+ *
+ * @param cls Closure (channel whose mq to activate).
+ */
+static void
+cadet_mq_send_now (void *cls)
+{
+  struct GNUNET_CADET_Channel *ch = cls;
+  struct GNUNET_MQ_Envelope *env = ch->pending_env;
+
+  ch->mq_cont = NULL;
+  if (0 == ch->allow_send)
+  {
+    /* how did we get here? */
+    GNUNET_break (0);
+    return;
+  }
+  if (NULL == env)
+  {
+    /* how did we get here? */
+    GNUNET_break (0);
+    return;
+  }
+  ch->allow_send--;
+  ch->pending_env = NULL;
+  GNUNET_MQ_send (ch->cadet->mq,
+                  env);
+  GNUNET_MQ_impl_send_continue (ch->mq);
+}
+
+
+/**
+ * Implement sending functionality of a message queue for
+ * us sending messages to a peer.
+ *
+ * Encapsulates the payload message in a #GNUNET_CADET_LocalData message
+ * in order to label the message with the channel ID and send the
+ * encapsulated message to the service.
+ *
+ * @param mq the message queue
+ * @param msg the message to send
+ * @param impl_state state of the implementation
+ */
+static void
+cadet_mq_send_impl (struct GNUNET_MQ_Handle *mq,
+                    const struct GNUNET_MessageHeader *msg,
+                    void *impl_state)
+{
+  struct GNUNET_CADET_Channel *ch = impl_state;
+  struct GNUNET_CADET_Handle *h = ch->cadet;
+  uint16_t msize;
+  struct GNUNET_MQ_Envelope *env;
+  struct GNUNET_CADET_LocalData *cadet_msg;
+
+  if (NULL == h->mq)
+  {
+    /* We're currently reconnecting, pretend this worked */
+    GNUNET_MQ_impl_send_continue (mq);
+    return;
+  }
+
+  /* check message size for sanity */
+  msize = ntohs (msg->size);
+  if (msize > GNUNET_CONSTANTS_MAX_CADET_MESSAGE_SIZE)
+  {
+    GNUNET_break (0);
+    GNUNET_MQ_impl_send_continue (mq);
+    return;
+  }
+  env = GNUNET_MQ_msg_nested_mh (cadet_msg,
+                                 GNUNET_MESSAGE_TYPE_CADET_LOCAL_DATA,
+                                 msg);
+  cadet_msg->ccn = ch->ccn;
+  GNUNET_assert (NULL == ch->pending_env);
+  ch->pending_env = env;
+  if (0 < ch->allow_send)
+    ch->mq_cont
+      = GNUNET_SCHEDULER_add_now (&cadet_mq_send_now,
+                                  ch);
+}
+
+
+/**
+ * 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
+cadet_mq_destroy_impl (struct GNUNET_MQ_Handle *mq,
+                       void *impl_state)
+{
+  struct GNUNET_CADET_Channel *ch = impl_state;
+
+  GNUNET_assert (mq == ch->mq);
+  ch->mq = NULL;
+}
+
+
+/**
+ * We had an error processing a message we forwarded from a peer to
+ * the CADET service.  We should just complain about it but otherwise
+ * continue processing.
+ *
+ * @param cls closure with our `struct GNUNET_CADET_Channel`
+ * @param error error code
+ */
+static void
+cadet_mq_error_handler (void *cls,
+                        enum GNUNET_MQ_Error error)
+{
+  struct GNUNET_CADET_Channel *ch = cls;
+
+  GNUNET_break (0);
+  if (GNUNET_MQ_ERROR_NO_MATCH == error)
+  {
+    /* Got a message we did not understand, still try to continue! */
+    GNUNET_CADET_receive_done (ch);
+  }
+  else
+  {
+    schedule_reconnect (ch->cadet);
+  }
+}
+
+
+/**
+ * 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
+cadet_mq_cancel_impl (struct GNUNET_MQ_Handle *mq,
+                     void *impl_state)
+{
+  struct GNUNET_CADET_Channel *ch = impl_state;
+
+  GNUNET_assert (NULL != ch->pending_env);
+  GNUNET_MQ_discard (ch->pending_env);
+  ch->pending_env = NULL;
+  if (NULL != ch->mq_cont)
+  {
+    GNUNET_SCHEDULER_cancel (ch->mq_cont);
+    ch->mq_cont = NULL;
+  }
+}
+
+
+/**
+ * Process the new channel notification and add it to the channels in the handle
+ *
+ * @param h     The cadet handle
+ * @param msg   A message with the details of the new incoming channel
+ */
+static void
+handle_channel_created (void *cls,
+                        const struct GNUNET_CADET_LocalChannelCreateMessage *msg)
+{
+  struct GNUNET_CADET_Handle *h = cls;
+  struct GNUNET_CADET_Channel *ch;
+  struct GNUNET_CADET_Port *port;
+  const struct GNUNET_HashCode *port_number;
+  struct GNUNET_CADET_ClientChannelNumber ccn;
+
+  ccn = msg->ccn;
+  port_number = &msg->port;
+  if (ntohl (ccn.channel_of_client) >= GNUNET_CADET_LOCAL_CHANNEL_ID_CLI)
+  {
+    GNUNET_break (0);
+    return;
+  }
+  port = find_port (h,
+                    port_number);
+  if (NULL == port)
+  {
+    /* We could have closed the port but the service didn't know about it yet
+     * This is not an error.
+     */
+    struct GNUNET_CADET_LocalChannelDestroyMessage *d_msg;
+    struct GNUNET_MQ_Envelope *env;
+
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "No handler for incoming channel %X (on port %s, recently closed?)\n",
+         ntohl (ccn.channel_of_client),
+         GNUNET_h2s (port_number));
+    env = GNUNET_MQ_msg (d_msg,
+                         GNUNET_MESSAGE_TYPE_CADET_LOCAL_CHANNEL_DESTROY);
+    d_msg->ccn = msg->ccn;
+    GNUNET_MQ_send (h->mq,
+                    env);
+    return;
+  }
+
+  ch = create_channel (h,
+                       &ccn);
+  ch->peer = msg->peer;
+  ch->cadet = h;
+  ch->incoming_port = port;
+  ch->options = ntohl (msg->opt);
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Creating incoming channel %X [%s] %p\n",
+       ntohl (ccn.channel_of_client),
+       GNUNET_h2s (port_number),
+       ch);
+
+  GNUNET_assert (NULL != port->connects);
+  ch->window_changes = port->window_changes;
+  ch->disconnects = port->disconnects;
+  ch->mq = GNUNET_MQ_queue_for_callbacks (&cadet_mq_send_impl,
+                                          &cadet_mq_destroy_impl,
+                                          &cadet_mq_cancel_impl,
+                                          ch,
+                                          port->handlers,
+                                          &cadet_mq_error_handler,
+                                          ch);
+  ch->ctx = port->connects (port->cls,
+                            ch,
+                            &msg->peer);
+  GNUNET_MQ_set_handlers_closure (ch->mq,
+                                  ch->ctx);
+}
+
+
+/**
+ * Process the channel destroy notification and free associated resources
+ *
+ * @param h     The cadet handle
+ * @param msg   A message with the details of the channel being destroyed
+ */
+static void
+handle_channel_destroy (void *cls,
+                        const struct GNUNET_CADET_LocalChannelDestroyMessage *msg)
+{
+  struct GNUNET_CADET_Handle *h = cls;
+  struct GNUNET_CADET_Channel *ch;
+
+  ch = find_channel (h,
+                     msg->ccn);
+  if (NULL == ch)
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Received channel destroy for unknown channel %X from CADET service (recently close?)\n",
+         ntohl (msg->ccn.channel_of_client));
+    return;
+  }
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received channel destroy for channel %X from CADET service\n",
+       ntohl (msg->ccn.channel_of_client));
+  destroy_channel (ch);
+}
+
+
+/**
+ * Check that message received from CADET service is well-formed.
+ *
+ * @param cls the `struct GNUNET_CADET_Handle`
+ * @param message the message we got
+ * @return #GNUNET_OK if the message is well-formed,
+ *         #GNUNET_SYSERR otherwise
+ */
+static int
+check_local_data (void *cls,
+                  const struct GNUNET_CADET_LocalData *message)
+{
+  uint16_t size;
+
+  size = ntohs (message->header.size);
+  if (sizeof (*message) + sizeof (struct GNUNET_MessageHeader) > size)
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
+}
+
+
+/**
+ * Process the incoming data packets, call appropriate handlers.
+ *
+ * @param h       The cadet handle
+ * @param message A message encapsulating the data
+ */
+static void
+handle_local_data (void *cls,
+                   const struct GNUNET_CADET_LocalData *message)
+{
+  struct GNUNET_CADET_Handle *h = cls;
+  const struct GNUNET_MessageHeader *payload;
+  struct GNUNET_CADET_Channel *ch;
+  uint16_t type;
+  int fwd;
+
+  ch = find_channel (h,
+                     message->ccn);
+  if (NULL == ch)
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Unknown channel %X for incoming data (recently closed?)\n",
+         ntohl (message->ccn.channel_of_client));
+    return;
+  }
+
+  payload = (const struct GNUNET_MessageHeader *) &message[1];
+  type = ntohs (payload->type);
+  fwd = ntohl (ch->ccn.channel_of_client) <= GNUNET_CADET_LOCAL_CHANNEL_ID_CLI;
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Got a %s data on channel %s [%X] of type %u\n",
+       fwd ? "FWD" : "BWD",
+       GNUNET_i2s (&ch->peer),
+       ntohl (message->ccn.channel_of_client),
+       type);
+  GNUNET_MQ_inject_message (ch->mq,
+                            payload);
+}
+
+
+/**
+ * Process a local ACK message, enabling the client to send
+ * more data to the service.
+ *
+ * @param h Cadet handle.
+ * @param message Message itself.
+ */
+static void
+handle_local_ack (void *cls,
+                  const struct GNUNET_CADET_LocalAck *message)
+{
+  struct GNUNET_CADET_Handle *h = cls;
+  struct GNUNET_CADET_Channel *ch;
+
+  ch = find_channel (h,
+                     message->ccn);
+  if (NULL == ch)
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "ACK on unknown channel %X\n",
+         ntohl (message->ccn.channel_of_client));
+    return;
+  }
+  ch->allow_send++;
+  if (NULL == ch->pending_env)
+  {
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "Got an ACK on mq channel %X, allow send now %u!\n",
+         ntohl (ch->ccn.channel_of_client),
+         ch->allow_send);
+    notify_window_size (ch);
+    return;
+  }
+  if (NULL != ch->mq_cont)
+    return; /* already working on it! */
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Got an ACK on mq channel %X, sending pending message!\n",
+       ntohl (ch->ccn.channel_of_client));
+  ch->mq_cont
+    = GNUNET_SCHEDULER_add_now (&cadet_mq_send_now,
+                                ch);
+}
+
+
+/**
+ * Generic error handler, called with the appropriate error code and
+ * the same closure specified at the creation of the message queue.
+ * Not every message queue implementation supports an error handler.
+ *
+ * @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_CADET_Handle *h = cls;
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "MQ ERROR: %u\n",
+              error);
+  GNUNET_MQ_destroy (h->mq);
+  h->mq = NULL;
+  reconnect (h);
+}
+
+
+/**
+ * Process a local reply about info on all tunnels, pass info to the user.
+ *
+ * @param cls Closure (Cadet handle).
+ * @param msg Message itself.
+ */
+static void
+handle_get_peers (void *cls,
+                  const struct GNUNET_CADET_LocalInfoPeer *msg)
+{
+  struct GNUNET_CADET_Handle *h = cls;
+
+  if (NULL == h->info_cb.peers_cb)
+    return;
+  h->info_cb.peers_cb (h->info_cls,
+                       &msg->destination,
+                       (int) ntohs (msg->tunnel),
+                       (unsigned int) ntohs (msg->paths),
+                       0);
+}
+
+
+/**
+ * Check that message received from CADET service is well-formed.
+ *
+ * @param cls the `struct GNUNET_CADET_Handle`
+ * @param message the message we got
+ * @return #GNUNET_OK if the message is well-formed,
+ *         #GNUNET_SYSERR otherwise
+ */
+static int
+check_get_peer (void *cls,
+                const struct GNUNET_CADET_LocalInfoPeer *message)
+{
+  size_t msize = sizeof (struct GNUNET_CADET_LocalInfoPeer);
+  const struct GNUNET_PeerIdentity *paths_array;
+  size_t esize;
+  unsigned int epaths;
+  unsigned int paths;
+  unsigned int peers;
+
+  esize = ntohs (message->header.size);
+  if (esize < msize)
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  if (0 != ((esize - msize) % sizeof (struct GNUNET_PeerIdentity)))
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  peers = (esize - msize) / sizeof (struct GNUNET_PeerIdentity);
+  epaths = ntohs (message->paths);
+  paths_array = (const struct GNUNET_PeerIdentity *) &message[1];
+  paths = 0;
+  for (unsigned int i = 0; i < peers; i++)
+    if (0 == memcmp (&paths_array[i],
+                     &message->destination,
+                     sizeof (struct GNUNET_PeerIdentity)))
+      paths++;
+  if (paths != epaths)
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
+}
+
+
+/**
+ * Process a local peer info reply, pass info to the user.
+ *
+ * @param cls Closure (Cadet handle).
+ * @param message Message itself.
+ */
+static void
+handle_get_peer (void *cls,
+                 const struct GNUNET_CADET_LocalInfoPeer *message)
+{
+  struct GNUNET_CADET_Handle *h = cls;
+  const struct GNUNET_PeerIdentity *paths_array;
+  unsigned int paths;
+  unsigned int path_length;
+  int neighbor;
+  unsigned int peers;
+
+  if (NULL == h->info_cb.peer_cb)
+    return;
+  paths = ntohs (message->paths);
+  paths_array = (const struct GNUNET_PeerIdentity *) &message[1];
+  peers = (ntohs (message->header.size) - sizeof (*message))
+          / sizeof (struct GNUNET_PeerIdentity);
+  path_length = 0;
+  neighbor = GNUNET_NO;
+
+  for (unsigned int i = 0; i < peers; i++)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                " %s\n",
+                GNUNET_i2s (&paths_array[i]));
+    path_length++;
+    if (0 == memcmp (&paths_array[i], &message->destination,
+                     sizeof (struct GNUNET_PeerIdentity)))
+    {
+      if (1 == path_length)
+        neighbor = GNUNET_YES;
+      path_length = 0;
+    }
+  }
+
+  /* Call Callback with tunnel info. */
+  paths_array = (const struct GNUNET_PeerIdentity *) &message[1];
+  h->info_cb.peer_cb (h->info_cls,
+                      &message->destination,
+                      (int) ntohs (message->tunnel),
+                      neighbor,
+                      paths,
+                      paths_array);
+}
+
+
+/**
+ * Process a local reply about info on all tunnels, pass info to the user.
+ *
+ * @param cls Closure (Cadet handle).
+ * @param message Message itself.
+ */
+static void
+handle_get_tunnels (void *cls,
+                    const struct GNUNET_CADET_LocalInfoTunnel *msg)
+{
+  struct GNUNET_CADET_Handle *h = cls;
+
+  if (NULL == h->info_cb.tunnels_cb)
+    return;
+  h->info_cb.tunnels_cb (h->info_cls,
+                         &msg->destination,
+                         ntohl (msg->channels),
+                         ntohl (msg->connections),
+                         ntohs (msg->estate),
+                         ntohs (msg->cstate));
+
+}
+
+
+/**
+ * Check that message received from CADET service is well-formed.
+ *
+ * @param cls the `struct GNUNET_CADET_Handle`
+ * @param msg the message we got
+ * @return #GNUNET_OK if the message is well-formed,
+ *         #GNUNET_SYSERR otherwise
+ */
+static int
+check_get_tunnel (void *cls,
+                  const struct GNUNET_CADET_LocalInfoTunnel *msg)
+{
+  unsigned int ch_n;
+  unsigned int c_n;
+  size_t esize;
+  size_t msize;
+
+  /* Verify message sanity */
+  msize = ntohs (msg->header.size);
+  esize = sizeof (struct GNUNET_CADET_LocalInfoTunnel);
+  if (esize > msize)
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  ch_n = ntohl (msg->channels);
+  c_n = ntohl (msg->connections);
+  esize += ch_n * sizeof (struct GNUNET_CADET_ChannelTunnelNumber);
+  esize += c_n * sizeof (struct GNUNET_CADET_ConnectionTunnelIdentifier);
+  if (msize != esize)
+  {
+    GNUNET_break_op (0);
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "m:%u, e: %u (%u ch, %u conn)\n",
+                (unsigned int) msize,
+                (unsigned int) esize,
+                ch_n,
+                c_n);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
+}
+
+
+/**
+ * Process a local tunnel info reply, pass info to the user.
+ *
+ * @param cls Closure (Cadet handle).
+ * @param msg Message itself.
+ */
+static void
+handle_get_tunnel (void *cls,
+                   const struct GNUNET_CADET_LocalInfoTunnel *msg)
+{
+  struct GNUNET_CADET_Handle *h = cls;
+  unsigned int ch_n;
+  unsigned int c_n;
+  const struct GNUNET_CADET_ConnectionTunnelIdentifier *conns;
+  const struct GNUNET_CADET_ChannelTunnelNumber *chns;
+
+  if (NULL == h->info_cb.tunnel_cb)
+    return;
+
+  ch_n = ntohl (msg->channels);
+  c_n = ntohl (msg->connections);
+
+  /* Call Callback with tunnel info. */
+  conns = (const struct GNUNET_CADET_ConnectionTunnelIdentifier *) &msg[1];
+  chns = (const struct GNUNET_CADET_ChannelTunnelNumber *) &conns[c_n];
+  h->info_cb.tunnel_cb (h->info_cls,
+                        &msg->destination,
+                        ch_n,
+                        c_n,
+                        chns,
+                        conns,
+                        ntohs (msg->estate),
+                        ntohs (msg->cstate));
+}
+
+
+/**
+ * Reconnect to the service, retransmit all infomation to try to restore the
+ * original state.
+ *
+ * @param h handle to the cadet
+ */
+static void
+reconnect (struct GNUNET_CADET_Handle *h)
+{
+  struct GNUNET_MQ_MessageHandler handlers[] = {
+    GNUNET_MQ_hd_fixed_size (channel_created,
+                             GNUNET_MESSAGE_TYPE_CADET_LOCAL_CHANNEL_CREATE,
+                             struct GNUNET_CADET_LocalChannelCreateMessage,
+                             h),
+    GNUNET_MQ_hd_fixed_size (channel_destroy,
+                             GNUNET_MESSAGE_TYPE_CADET_LOCAL_CHANNEL_DESTROY,
+                             struct GNUNET_CADET_LocalChannelDestroyMessage,
+                             h),
+    GNUNET_MQ_hd_var_size (local_data,
+                           GNUNET_MESSAGE_TYPE_CADET_LOCAL_DATA,
+                           struct GNUNET_CADET_LocalData,
+                           h),
+    GNUNET_MQ_hd_fixed_size (local_ack,
+                             GNUNET_MESSAGE_TYPE_CADET_LOCAL_ACK,
+                             struct GNUNET_CADET_LocalAck,
+                             h),
+    GNUNET_MQ_hd_fixed_size (get_peers,
+                             GNUNET_MESSAGE_TYPE_CADET_LOCAL_INFO_PEERS,
+                             struct GNUNET_CADET_LocalInfoPeer,
+                             h),
+    GNUNET_MQ_hd_var_size (get_peer,
+                           GNUNET_MESSAGE_TYPE_CADET_LOCAL_INFO_PEER,
+                           struct GNUNET_CADET_LocalInfoPeer,
+                           h),
+    GNUNET_MQ_hd_fixed_size (get_tunnels,
+                             GNUNET_MESSAGE_TYPE_CADET_LOCAL_INFO_TUNNELS,
+                             struct GNUNET_CADET_LocalInfoTunnel,
+                             h),
+    GNUNET_MQ_hd_var_size (get_tunnel,
+                           GNUNET_MESSAGE_TYPE_CADET_LOCAL_INFO_TUNNEL,
+                           struct GNUNET_CADET_LocalInfoTunnel,
+                           h),
+    GNUNET_MQ_handler_end ()
+  };
+
+  h->mq = GNUNET_CLIENT_connect (h->cfg,
+                                 "cadet",
+                                 handlers,
+                                 &handle_mq_error,
+                                 h);
+  if (NULL == h->mq)
+  {
+    schedule_reconnect (h);
+    return;
+  }
+  h->reconnect_time = GNUNET_TIME_UNIT_MILLISECONDS;
+}
+
+
+/**
+ * Function called during #GNUNET_CADET_disconnect() to destroy
+ * all channels that are still open.
+ *
+ * @param cls the `struct GNUNET_CADET_Handle`
+ * @param cid chanenl ID
+ * @param value a `struct GNUNET_CADET_Channel` to destroy
+ * @return #GNUNET_OK (continue to iterate)
+ */
+static int
+destroy_channel_cb (void *cls,
+                    uint32_t cid,
+                    void *value)
+{
+  /* struct GNUNET_CADET_Handle *handle = cls; */
+  struct GNUNET_CADET_Channel *ch = value;
+
+  if (ntohl (ch->ccn.channel_of_client) >= GNUNET_CADET_LOCAL_CHANNEL_ID_CLI)
+  {
+    GNUNET_break (0);
+    LOG (GNUNET_ERROR_TYPE_DEBUG,
+         "channel %X not destroyed\n",
+         ntohl (ch->ccn.channel_of_client));
+  }
+  destroy_channel (ch);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Function called during #GNUNET_CADET_disconnect() to destroy
+ * all ports that are still open.
+ *
+ * @param cls the `struct GNUNET_CADET_Handle`
+ * @param id port ID
+ * @param value a `struct GNUNET_CADET_Channel` to destroy
+ * @return #GNUNET_OK (continue to iterate)
+ */
+static int
+destroy_port_cb (void *cls,
+                 const struct GNUNET_HashCode *id,
+                 void *value)
+{
+  /* struct GNUNET_CADET_Handle *handle = cls; */
+  struct GNUNET_CADET_Port *port = value;
+
+  /* This is a warning, the app should have cleanly closed all open ports */
+  GNUNET_break (0);
+  GNUNET_CADET_close_port (port);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Disconnect from the cadet service. All channels will be destroyed. All channel
+ * disconnect callbacks will be called on any still connected peers, notifying
+ * about their disconnection. The registered inbound channel cleaner will be
+ * called should any inbound channels still exist.
+ *
+ * @param handle connection to cadet to disconnect
+ */
+void
+GNUNET_CADET_disconnect (struct GNUNET_CADET_Handle *handle)
+{
+  GNUNET_CONTAINER_multihashmap_iterate (handle->ports,
+                                         &destroy_port_cb,
+                                         handle);
+  GNUNET_CONTAINER_multihashmap_destroy (handle->ports);
+  handle->ports = NULL;
+  GNUNET_CONTAINER_multihashmap32_iterate (handle->channels,
+                                           &destroy_channel_cb,
+                                           handle);
+  GNUNET_CONTAINER_multihashmap32_destroy (handle->channels);
+  handle->channels = NULL;
+  if (NULL != handle->mq)
+  {
+    GNUNET_MQ_destroy (handle->mq);
+    handle->mq = NULL;
+  }
+  if (NULL != handle->reconnect_task)
+  {
+    GNUNET_SCHEDULER_cancel (handle->reconnect_task);
+    handle->reconnect_task = NULL;
+  }
+  GNUNET_free (handle);
+}
+
+
+/**
+ * Close a port opened with @a GNUNET_CADET_open_port().
+ * The @a new_channel callback will no longer be called.
+ *
+ * @param p Port handle.
+ */
+void
+GNUNET_CADET_close_port (struct GNUNET_CADET_Port *p)
+{
+  struct GNUNET_CADET_PortMessage *msg;
+  struct GNUNET_MQ_Envelope *env;
+
+  env = GNUNET_MQ_msg (msg,
+                       GNUNET_MESSAGE_TYPE_CADET_LOCAL_PORT_CLOSE);
+  msg->port = p->id;
+  GNUNET_MQ_send (p->cadet->mq,
+                  env);
+  GNUNET_assert (GNUNET_YES ==
+                 GNUNET_CONTAINER_multihashmap_remove (p->cadet->ports,
+                                                       &p->id,
+                                                       p));
+  GNUNET_free_non_null (p->handlers);
+  GNUNET_free (p);
+}
+
+
+/**
+ * Destroy an existing channel.
+ *
+ * The existing end callback for the channel will be called immediately.
+ * Any pending outgoing messages will be sent but no incoming messages will be
+ * accepted and no data callbacks will be called.
+ *
+ * @param channel Channel handle, becomes invalid after this call.
+ */
+void
+GNUNET_CADET_channel_destroy (struct GNUNET_CADET_Channel *channel)
+{
+  struct GNUNET_CADET_Handle *h = channel->cadet;
+  struct GNUNET_CADET_LocalChannelDestroyMessage *msg;
+  struct GNUNET_MQ_Envelope *env;
+
+  if (NULL != h->mq)
+  {
+    env = GNUNET_MQ_msg (msg,
+                         GNUNET_MESSAGE_TYPE_CADET_LOCAL_CHANNEL_DESTROY);
+    msg->ccn = channel->ccn;
+    GNUNET_MQ_send (h->mq,
+                    env);
+  }
+  destroy_channel (channel);
+}
+
+
+/**
+ * Get information about a channel.
+ *
+ * @param channel Channel handle.
+ * @param option Query (GNUNET_CADET_OPTION_*).
+ * @param ... dependant on option, currently not used
+ *
+ * @return Union with an answer to the query.
+ */
+const union GNUNET_CADET_ChannelInfo *
+GNUNET_CADET_channel_get_info (struct GNUNET_CADET_Channel *channel,
+                               enum GNUNET_CADET_ChannelOption option,
+                               ...)
+{
+  static int bool_flag;
+
+  switch (option)
+  {
+    case GNUNET_CADET_OPTION_NOBUFFER:
+    case GNUNET_CADET_OPTION_RELIABLE:
+    case GNUNET_CADET_OPTION_OUT_OF_ORDER:
+      if (0 != (option & channel->options))
+        bool_flag = GNUNET_YES;
+      else
+        bool_flag = GNUNET_NO;
+      return (const union GNUNET_CADET_ChannelInfo *) &bool_flag;
+      break;
+    case GNUNET_CADET_OPTION_PEER:
+      return (const union GNUNET_CADET_ChannelInfo *) &channel->peer;
+      break;
+    default:
+      GNUNET_break (0);
+      return NULL;
+  }
+}
+
+
+/**
+ * Send an ack on the channel to confirm the processing of a message.
+ *
+ * @param ch Channel on which to send the ACK.
+ */
+void
+GNUNET_CADET_receive_done (struct GNUNET_CADET_Channel *channel)
+{
+  struct GNUNET_CADET_LocalAck *msg;
+  struct GNUNET_MQ_Envelope *env;
+
+  env = GNUNET_MQ_msg (msg,
+                       GNUNET_MESSAGE_TYPE_CADET_LOCAL_ACK);
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Sending ACK on channel %X\n",
+       ntohl (channel->ccn.channel_of_client));
+  msg->ccn = channel->ccn;
+  GNUNET_MQ_send (channel->cadet->mq,
+                  env);
+}
+
+
+/**
+ * Send message of @a type to CADET service of @a h
+ *
+ * @param h handle to CADET service
+ * @param type message type of trivial information request to send
+ */
+static void
+send_info_request (struct GNUNET_CADET_Handle *h,
+                   uint16_t type)
+{
+  struct GNUNET_MessageHeader *msg;
+  struct GNUNET_MQ_Envelope *env;
+
+  env = GNUNET_MQ_msg (msg,
+                       type);
+  GNUNET_MQ_send (h->mq,
+                  env);
+}
+
+
+/**
+ * Request a debug dump on the service's STDERR.
+ *
+ * WARNING: unstable API, likely to change in the future!
+ *
+ * @param h cadet handle
+ */
+void
+GNUNET_CADET_request_dump (struct GNUNET_CADET_Handle *h)
+{
+  send_info_request (h,
+                     GNUNET_MESSAGE_TYPE_CADET_LOCAL_INFO_DUMP);
+}
+
+
+/**
+ * Request information about peers known to the running cadet service.
+ * The callback will be called for every peer known to the service.
+ * Only one info request (of any kind) can be active at once.
+ *
+ * WARNING: unstable API, likely to change in the future!
+ *
+ * @param h Handle to the cadet peer.
+ * @param callback Function to call with the requested data.
+ * @param callback_cls Closure for @c callback.
+ * @return #GNUNET_OK / #GNUNET_SYSERR
+ */
+int
+GNUNET_CADET_get_peers (struct GNUNET_CADET_Handle *h,
+                       GNUNET_CADET_PeersCB callback,
+                       void *callback_cls)
+{
+  if (NULL != h->info_cb.peers_cb)
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  send_info_request (h,
+                     GNUNET_MESSAGE_TYPE_CADET_LOCAL_INFO_PEERS);
+  h->info_cb.peers_cb = callback;
+  h->info_cls = callback_cls;
+  return GNUNET_OK;
+}
+
+
+/**
+ * Cancel a peer info request. The callback will not be called (anymore).
+ *
+ * WARNING: unstable API, likely to change in the future!
+ *
+ * @param h Cadet handle.
+ * @return Closure given to GNUNET_CADET_get_peers().
+ */
+void *
+GNUNET_CADET_get_peers_cancel (struct GNUNET_CADET_Handle *h)
+{
+  void *cls = h->info_cls;
+
+  h->info_cb.peers_cb = NULL;
+  h->info_cls = NULL;
+  return cls;
+}
+
+
+/**
+ * Request information about a peer known to the running cadet peer.
+ * The callback will be called for the tunnel once.
+ * Only one info request (of any kind) can be active at once.
+ *
+ * WARNING: unstable API, likely to change in the future!
+ *
+ * @param h Handle to the cadet peer.
+ * @param id Peer whose tunnel to examine.
+ * @param callback Function to call with the requested data.
+ * @param callback_cls Closure for @c callback.
+ * @return #GNUNET_OK / #GNUNET_SYSERR
+ */
+int
+GNUNET_CADET_get_peer (struct GNUNET_CADET_Handle *h,
+                       const struct GNUNET_PeerIdentity *id,
+                       GNUNET_CADET_PeerCB callback,
+                       void *callback_cls)
+{
+  struct GNUNET_CADET_LocalInfo *msg;
+  struct GNUNET_MQ_Envelope *env;
+
+  if (NULL != h->info_cb.peer_cb)
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  env = GNUNET_MQ_msg (msg,
+                       GNUNET_MESSAGE_TYPE_CADET_LOCAL_INFO_PEER);
+  msg->peer = *id;
+  GNUNET_MQ_send (h->mq,
+                  env);
+  h->info_cb.peer_cb = callback;
+  h->info_cls = callback_cls;
+  return GNUNET_OK;
+}
+
+
+/**
+ * Request information about tunnels of the running cadet peer.
+ * The callback will be called for every tunnel of the service.
+ * Only one info request (of any kind) can be active at once.
+ *
+ * WARNING: unstable API, likely to change in the future!
+ *
+ * @param h Handle to the cadet peer.
+ * @param callback Function to call with the requested data.
+ * @param callback_cls Closure for @c callback.
+ * @return #GNUNET_OK / #GNUNET_SYSERR
+ */
+int
+GNUNET_CADET_get_tunnels (struct GNUNET_CADET_Handle *h,
+                         GNUNET_CADET_TunnelsCB callback,
+                         void *callback_cls)
+{
+  if (NULL != h->info_cb.tunnels_cb)
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  send_info_request (h,
+                     GNUNET_MESSAGE_TYPE_CADET_LOCAL_INFO_TUNNELS);
+  h->info_cb.tunnels_cb = callback;
+  h->info_cls = callback_cls;
+  return GNUNET_OK;
+}
+
+
+/**
+ * Cancel a monitor request. The monitor callback will not be called.
+ *
+ * @param h Cadet handle.
+ * @return Closure given to GNUNET_CADET_get_tunnels().
+ */
+void *
+GNUNET_CADET_get_tunnels_cancel (struct GNUNET_CADET_Handle *h)
+{
+  void *cls = h->info_cls;
+
+  h->info_cb.tunnels_cb = NULL;
+  h->info_cls = NULL;
+  return cls;
+}
+
+
+/**
+ * Request information about a tunnel of the running cadet peer.
+ * The callback will be called for the tunnel once.
+ * Only one info request (of any kind) can be active at once.
+ *
+ * WARNING: unstable API, likely to change in the future!
+ *
+ * @param h Handle to the cadet peer.
+ * @param id Peer whose tunnel to examine.
+ * @param callback Function to call with the requested data.
+ * @param callback_cls Closure for @c callback.
+ * @return #GNUNET_OK / #GNUNET_SYSERR
+ */
+int
+GNUNET_CADET_get_tunnel (struct GNUNET_CADET_Handle *h,
+                        const struct GNUNET_PeerIdentity *id,
+                        GNUNET_CADET_TunnelCB callback,
+                        void *callback_cls)
+{
+  struct GNUNET_CADET_LocalInfo *msg;
+  struct GNUNET_MQ_Envelope *env;
+
+  if (NULL != h->info_cb.tunnel_cb)
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  env = GNUNET_MQ_msg (msg,
+                       GNUNET_MESSAGE_TYPE_CADET_LOCAL_INFO_TUNNEL);
+  msg->peer = *id;
+  GNUNET_MQ_send (h->mq,
+                  env);
+  h->info_cb.tunnel_cb = callback;
+  h->info_cls = callback_cls;
+  return GNUNET_OK;
+}
+
+
+/**
+ * Transitional function to convert an unsigned int port to a hash value.
+ * WARNING: local static value returned, NOT reentrant!
+ * WARNING: do not use this function for new code!
+ *
+ * @param port Numerical port (unsigned int format).
+ *
+ * @return A GNUNET_HashCode usable for the new CADET API.
+ */
+const struct GNUNET_HashCode *
+GC_u2h (uint32_t port)
+{
+  static struct GNUNET_HashCode hash;
+
+  GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+              "This is a transitional function, use proper crypto hashes as CADET ports\n");
+  GNUNET_CRYPTO_hash (&port,
+                      sizeof (port),
+                      &hash);
+  return &hash;
+}
+
+
+/**
+ * Connect to the MQ-based cadet service.
+ *
+ * @param cfg Configuration to use.
+ *
+ * @return Handle to the cadet service NULL on error.
+ */
+struct GNUNET_CADET_Handle *
+GNUNET_CADET_connecT (const struct GNUNET_CONFIGURATION_Handle *cfg)
+{
+  struct GNUNET_CADET_Handle *h;
+
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "GNUNET_CADET_connecT()\n");
+  h = GNUNET_new (struct GNUNET_CADET_Handle);
+  h->cfg = cfg;
+  h->ports = GNUNET_CONTAINER_multihashmap_create (4,
+                                                   GNUNET_YES);
+  h->channels = GNUNET_CONTAINER_multihashmap32_create (4);
+  reconnect (h);
+  if (NULL == h->mq)
+  {
+    GNUNET_break (0);
+    GNUNET_CADET_disconnect (h);
+    return NULL;
+  }
+  h->next_ccn.channel_of_client = htonl (GNUNET_CADET_LOCAL_CHANNEL_ID_CLI);
+  h->reconnect_time = GNUNET_TIME_UNIT_MILLISECONDS;
+  h->reconnect_task = NULL;
+
+  return h;
+}
+
+
+/**
+ * Open a port to receive incomming MQ-based channels.
+ *
+ * @param h CADET handle.
+ * @param port Hash identifying the port.
+ * @param connects Function called when an incoming channel is connected.
+ * @param connects_cls Closure for the @a connects handler.
+ * @param window_changes Function called when the transmit window size changes.
+ * @param disconnects Function called when a channel is disconnected.
+ * @param handlers Callbacks for messages we care about, NULL-terminated.
+ * @return Port handle.
+ */
+struct GNUNET_CADET_Port *
+GNUNET_CADET_open_porT (struct GNUNET_CADET_Handle *h,
+                        const struct GNUNET_HashCode *port,
+                        GNUNET_CADET_ConnectEventHandler connects,
+                        void * connects_cls,
+                        GNUNET_CADET_WindowSizeEventHandler window_changes,
+                        GNUNET_CADET_DisconnectEventHandler disconnects,
+                        const struct GNUNET_MQ_MessageHandler *handlers)
+{
+  struct GNUNET_CADET_PortMessage *msg;
+  struct GNUNET_MQ_Envelope *env;
+  struct GNUNET_CADET_Port *p;
+
+  GNUNET_assert (NULL != connects);
+  GNUNET_assert (NULL != disconnects);
+
+  p = GNUNET_new (struct GNUNET_CADET_Port);
+  p->cadet = h;
+  p->id = *port;
+  p->connects = connects;
+  p->cls = connects_cls;
+  p->window_changes = window_changes;
+  p->disconnects = disconnects;
+  p->handlers = GNUNET_MQ_copy_handlers (handlers);
+
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CONTAINER_multihashmap_put (h->ports,
+                                                    &p->id,
+                                                    p,
+                                                    GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
+
+  env = GNUNET_MQ_msg (msg,
+                       GNUNET_MESSAGE_TYPE_CADET_LOCAL_PORT_OPEN);
+  msg->port = p->id;
+  GNUNET_MQ_send (h->mq,
+                  env);
+  return p;
+}
+
+
+/**
+ * Create a new channel towards a remote peer.
+ *
+ * If the destination port is not open by any peer or the destination peer
+ * does not accept the channel, #GNUNET_CADET_ChannelEndHandler will be called
+ * for this channel.
+ *
+ * @param h CADET handle.
+ * @param channel_cls Closure for the channel. It's given to:
+ *                    - The disconnect handler @a disconnects
+ *                    - Each message type callback in @a handlers
+ * @param destination Peer identity the channel should go to.
+ * @param port Identification of the destination port.
+ * @param options CadetOption flag field, with all desired option bits set to 1.
+ * @param window_changes Function called when the transmit window size changes.
+ * @param disconnects Function called when the channel is disconnected.
+ * @param handlers Callbacks for messages we care about, NULL-terminated.
+ * @return Handle to the channel.
+ */
+struct GNUNET_CADET_Channel *
+GNUNET_CADET_channel_creatE (struct GNUNET_CADET_Handle *h,
+                             void *channel_cls,
+                             const struct GNUNET_PeerIdentity *destination,
+                             const struct GNUNET_HashCode *port,
+                             enum GNUNET_CADET_ChannelOption options,
+                             GNUNET_CADET_WindowSizeEventHandler window_changes,
+                             GNUNET_CADET_DisconnectEventHandler disconnects,
+                             const struct GNUNET_MQ_MessageHandler *handlers)
+{
+  struct GNUNET_CADET_Channel *ch;
+  struct GNUNET_CADET_LocalChannelCreateMessage *msg;
+  struct GNUNET_MQ_Envelope *env;
+
+  GNUNET_assert (NULL != disconnects);
+  ch = create_channel (h,
+                       NULL);
+  ch->ctx = channel_cls;
+  ch->peer = *destination;
+  ch->options = options;
+  ch->window_changes = window_changes;
+  ch->disconnects = disconnects;
+
+  /* Create MQ for channel */
+  ch->mq = GNUNET_MQ_queue_for_callbacks (&cadet_mq_send_impl,
+                                          &cadet_mq_destroy_impl,
+                                          &cadet_mq_cancel_impl,
+                                          ch,
+                                          handlers,
+                                          &cadet_mq_error_handler,
+                                          ch);
+  GNUNET_MQ_set_handlers_closure (ch->mq, channel_cls);
+
+  /* Request channel creation to service */
+  env = GNUNET_MQ_msg (msg,
+                       GNUNET_MESSAGE_TYPE_CADET_LOCAL_CHANNEL_CREATE);
+  msg->ccn = ch->ccn;
+  msg->port = *port;
+  msg->peer = *destination;
+  msg->opt = htonl (options);
+  GNUNET_MQ_send (h->mq,
+                  env);
+  return ch;
+}
+
+
+/**
+ * Obtain the message queue for a connected peer.
+ *
+ * @param channel The channel handle from which to get the MQ.
+ *
+ * @return NULL if @a channel is not yet connected.
+ */
+struct GNUNET_MQ_Handle *
+GNUNET_CADET_get_mq (const struct GNUNET_CADET_Channel *channel)
+{
+  return channel->mq;
+}
+
+/* end of cadet_api.c */