cadet_api.c

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/*
     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 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
 */
#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__)
 
struct GNUNET_CADET_Handle
{
  struct GNUNET_MQ_Handle *mq;
 
  struct GNUNET_CONTAINER_MultiHashMap *ports;
 
  struct GNUNET_CONTAINER_MultiHashMap32 *channels;
 
  struct GNUNET_CADET_ClientChannelNumber next_ccn;
 
  const struct GNUNET_CONFIGURATION_Handle *cfg;
 
  struct GNUNET_SCHEDULER_Task *reconnect_task;
 
  struct GNUNET_TIME_Relative reconnect_time;
};
 
struct GNUNET_CADET_Port
{
  struct GNUNET_HashCode id;
 
  struct GNUNET_CADET_Handle *cadet;
 
  void *cls;
 
  GNUNET_CADET_ConnectEventHandler connects;
 
  void *connects_cls;
 
  GNUNET_CADET_WindowSizeEventHandler window_changes;
 
  GNUNET_CADET_DisconnectEventHandler disconnects;
 
  struct GNUNET_MQ_MessageHandler *handlers;
};
 
 
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);
}
 
 
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));
}
 
 
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;
}
 
 
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",
       htonl (ch->ccn.channel_of_client),
       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);
}
 
 
static void
reconnect (struct GNUNET_CADET_Handle *h);
 
 
static int
open_port_cb (void *cls, const struct GNUNET_HashCode *id, void *value)
{
  struct GNUNET_CADET_Handle *h = cls;
  struct GNUNET_CADET_Port *port = value;
  struct GNUNET_CADET_PortMessage *msg;
  struct GNUNET_MQ_Envelope *env;
 
  (void) id;
  env = GNUNET_MQ_msg (msg, GNUNET_MESSAGE_TYPE_CADET_LOCAL_PORT_OPEN);
  msg->port = port->id;
  GNUNET_MQ_send (h->mq, env);
  return GNUNET_OK;
}
 
 
static void
reconnect_cbk (void *cls)
{
  struct GNUNET_CADET_Handle *h = cls;
 
  h->reconnect_task = NULL;
  h->reconnect_time = GNUNET_TIME_STD_BACKOFF (h->reconnect_time);
  reconnect (h);
  GNUNET_CONTAINER_multihashmap_iterate (h->ports, &open_port_cb, h);
}
 
 
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);
}
 
 
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_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sending message on channel %s to CADET, new window size is %u\n",
              GNUNET_i2s (&ch->peer),
              ch->allow_send);
  GNUNET_MQ_send (ch->cadet->mq, env);
  GNUNET_MQ_impl_send_continue (ch->mq);
}
 
 
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 *orig_env;
  struct GNUNET_MQ_Envelope *env;
  struct GNUNET_CADET_LocalData *cadet_msg;
  enum GNUNET_MQ_PriorityPreferences pp;
 
  if (NULL == h->mq)
  {
    /* We're currently reconnecting, pretend this worked */
    GNUNET_MQ_impl_send_continue (mq);
    return;
  }
  orig_env = GNUNET_MQ_get_current_envelope (mq);
  pp = GNUNET_MQ_env_get_options (orig_env);
 
  /* 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;
  cadet_msg->pp = htonl ((uint32_t) pp);
  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);
}
 
 
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;
}
 
 
static void
cadet_mq_error_handler (void *cls, enum GNUNET_MQ_Error error)
{
  struct GNUNET_CADET_Channel *ch = cls;
 
  if (GNUNET_MQ_ERROR_NO_MATCH == error)
  {
    /* Got a message we did not understand, still try to continue! */
    GNUNET_break_op (0);
    GNUNET_CADET_receive_done (ch);
  }
  else
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "MQ error in communication with CADET: %d\n",
                error);
    if (NULL != ch->disconnects)
      ch->disconnects (ch->ctx, ch);
    GNUNET_CADET_channel_destroy (ch);
  }
}
 
 
static void
cadet_mq_cancel_impl (struct GNUNET_MQ_Handle *mq, void *impl_state)
{
  struct GNUNET_CADET_Channel *ch = impl_state;
 
  (void) mq;
  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;
  }
}
 
 
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->incoming_port = port;
  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);
}
 
 
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);
}
 
 
static int
check_local_data (void *cls,
                  const struct GNUNET_CADET_LocalData *message)
{
  uint16_t size;
 
  (void) cls;
  size = ntohs (message->header.size);
  if (sizeof(*message) + sizeof(struct GNUNET_MessageHeader) > size)
  {
    GNUNET_break (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}
 
 
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);
}
 
 
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++;
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Got an ACK on mq channel %X (peer %s); new window size is %u!\n",
       ntohl (ch->ccn.channel_of_client),
       GNUNET_i2s (&ch->peer),
       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! */
  ch->mq_cont = GNUNET_SCHEDULER_add_now (&cadet_mq_send_now, ch);
}
 
 
static int
destroy_channel_cb (void *cls, uint32_t cid, void *value)
{
  /* struct GNUNET_CADET_Handle *handle = cls; */
  struct GNUNET_CADET_Channel *ch = value;
 
  (void) cls;
  (void) cid;
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Destroying channel due to GNUNET_CADET_disconnect()\n");
  destroy_channel (ch);
  return GNUNET_OK;
}
 
 
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_CONTAINER_multihashmap32_iterate (h->channels, &destroy_channel_cb, h);
  GNUNET_MQ_destroy (h->mq);
  h->mq = NULL;
  GNUNET_assert (NULL == h->reconnect_task);
  h->reconnect_task =
    GNUNET_SCHEDULER_add_delayed (h->reconnect_time, &reconnect_cbk, h);
}
 
 
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_handler_end () };
 
  GNUNET_assert (NULL == h->mq);
  h->mq =
    GNUNET_CLIENT_connect (h->cfg, "cadet", handlers, &handle_mq_error, h);
}
 
 
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;
 
  (void) cls;
  (void) id;
  /* This is a warning, the app should have cleanly closed all open ports */
  GNUNET_break (0);
  GNUNET_CADET_close_port (port);
  return GNUNET_OK;
}
 
 
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);
}
 
 
void
GNUNET_CADET_close_port (struct GNUNET_CADET_Port *p)
{
  GNUNET_assert (
    GNUNET_YES ==
    GNUNET_CONTAINER_multihashmap_remove (p->cadet->ports, &p->id, p));
  if (NULL != p->cadet->mq)
  {
    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_free (p->handlers);
  GNUNET_free (p);
}
 
 
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);
  }
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Destroying channel due to GNUNET_CADET_channel_destroy()\n");
  channel->disconnects = NULL;
  destroy_channel (channel);
}
 
 
const union GNUNET_CADET_ChannelInfo *
GNUNET_CADET_channel_get_info (struct GNUNET_CADET_Channel *channel,
                               enum GNUNET_CADET_ChannelInfoOption option,
                               ...)
{
  switch (option)
  {
  case GNUNET_CADET_OPTION_PEER:
    return (const union GNUNET_CADET_ChannelInfo *) &channel->peer;
 
  default:
    GNUNET_break (0);
    return NULL;
  }
}
 
 
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);
}
 
 
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);
  return h;
}
 
 
static void
return_agpl (void *cls,
             const struct GNUNET_MessageHeader *msg)
{
  struct GNUNET_SERVICE_Client *client = cls;
  struct GNUNET_MQ_Handle *mq;
  struct GNUNET_MQ_Envelope *env;
  struct GNUNET_MessageHeader *res;
  size_t slen;
  /* FIXME: this is a bug, uses always GNUnet PD while we would
     actually WANT to use the PD of the CADET application here! */
  const struct GNUNET_OS_ProjectData *pd =
    GNUNET_OS_project_data_gnunet ();
 
  (void) msg;
  slen = strlen (pd->agpl_url) + 1;
  env = GNUNET_MQ_msg_extra (res,
                             GNUNET_MESSAGE_TYPE_RESPONSE_AGPL,
                             slen);
  memcpy (&res[1],
          pd->agpl_url,
          slen);
  mq = GNUNET_SERVICE_client_get_mq (client);
  GNUNET_MQ_send (mq,
                  env);
  GNUNET_SERVICE_client_continue (client);
}
 
 
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_Port *p;
  /* FIXME: this is a bug, uses always GNUnet PD while we would
     actually WANT to use the PD of the CADET application here! */
  const struct GNUNET_OS_ProjectData *pd =
    GNUNET_OS_project_data_gnunet ();
 
  GNUNET_assert (NULL != connects);
  GNUNET_assert (NULL != disconnects);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Listening to CADET port %s\n",
              GNUNET_h2s (port));
 
  p = GNUNET_new (struct GNUNET_CADET_Port);
  p->cadet = h;
  p->id = *port;
  if (GNUNET_OK != GNUNET_CONTAINER_multihashmap_put (
        h->ports,
        &p->id,
        p,
        GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY))
  {
    GNUNET_free (p);
    return NULL;
  }
  p->connects = connects;
  p->cls = connects_cls;
  p->window_changes = window_changes;
  p->disconnects = disconnects;
  p->handlers = (NULL == pd->agpl_url)
                ? GNUNET_MQ_copy_handlers (handlers)
                : GNUNET_MQ_copy_handlers2 (handlers, &return_agpl, NULL);
 
  GNUNET_assert (GNUNET_OK == open_port_cb (h, &p->id, p));
  return p;
}
 
 
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,
                             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);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Creating channel to peer %s at port %s\n",
              GNUNET_i2s (destination),
              GNUNET_h2s (port));
  ch = create_channel (h, NULL);
  ch->ctx = channel_cls;
  ch->peer = *destination;
  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;
  GNUNET_MQ_send (h->mq, env);
  return ch;
}
 
 
struct GNUNET_MQ_Handle *
GNUNET_CADET_get_mq (const struct GNUNET_CADET_Channel *channel)
{
  return channel->mq;
}
 
 
/* end of cadet_api.c */