gnunet-service-conversation.c

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/*
   This file is part of GNUnet.
   Copyright (C) 2013, 2016, 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_protocols.h"
#include "gnunet_applications.h"
#include "gnunet_constants.h"
#include "gnunet_signatures.h"
#include "gnunet_cadet_service.h"
#include "gnunet_conversation_service.h"
#include "conversation.h"


#define RING_TIMEOUT GNUNET_TIME_UNIT_DAYS


struct Line;

enum ChannelStatus {
  CS_CALLEE_INIT,

  CS_CALLEE_RINGING,

  CS_CALLEE_CONNECTED,

  CS_CALLEE_SHUTDOWN,

  CS_CALLER_CALLING,

  CS_CALLER_CONNECTED,

  CS_CALLER_SHUTDOWN
};


struct Channel {
  struct Channel *next;

  struct Channel *prev;

  struct Line *line;

  struct GNUNET_CADET_Channel *channel;

  struct GNUNET_MQ_Handle *mq;

  struct GNUNET_MQ_Envelope *env;

  uint32_t cid;

  enum ChannelStatus status;

  int8_t suspended_remote;

  int8_t suspended_local;
};


struct Line {
  struct Channel *channel_head;

  struct Channel *channel_tail;

  struct GNUNET_SERVICE_Client *client;

  struct GNUNET_MQ_Handle *mq;

  struct GNUNET_CADET_Port *port;

  struct GNUNET_HashCode line_port;

  uint32_t cid_gen;
};


static const struct GNUNET_CONFIGURATION_Handle *cfg;

static struct GNUNET_CADET_Handle *cadet;

static struct GNUNET_PeerIdentity my_identity;


static struct Channel *
find_channel_by_line(struct Line *line, uint32_t cid)
{
  for (struct Channel *ch = line->channel_head; NULL != ch; ch = ch->next)
    if (cid == ch->cid)
      return ch;
  return NULL;
}


static void
handle_client_pickup_message(void *cls,
                             const struct ClientPhonePickupMessage *msg)
{
  struct Line *line = cls;
  struct CadetPhonePickupMessage *mppm;
  struct GNUNET_MQ_Envelope *env;
  struct Channel *ch;

  if (NULL == line->port)
    {
      /* we never opened the port, bad client! */
      GNUNET_break_op(0);
      GNUNET_SERVICE_client_drop(line->client);
      return;
    }
  for (ch = line->channel_head; NULL != ch; ch = ch->next)
    if (msg->cid == ch->cid)
      break;
  if (NULL == ch)
    {
      /* could have been destroyed asynchronously, ignore message */
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Channel %u not found\n", msg->cid);
      GNUNET_SERVICE_client_continue(line->client);
      return;
    }
  switch (ch->status)
    {
    case CS_CALLEE_INIT:
      GNUNET_break(0);
      GNUNET_SERVICE_client_drop(line->client);
      return;

    case CS_CALLEE_RINGING:
      ch->status = CS_CALLEE_CONNECTED;
      break;

    case CS_CALLEE_CONNECTED:
      GNUNET_break(0);
      GNUNET_SERVICE_client_drop(line->client);
      return;

    case CS_CALLEE_SHUTDOWN:
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
                 "Ignoring client's PICKUP message, line is in SHUTDOWN\n");
      break;

    case CS_CALLER_CALLING:
    case CS_CALLER_CONNECTED:
    case CS_CALLER_SHUTDOWN:
      GNUNET_break(0);
      GNUNET_SERVICE_client_drop(line->client);
      return;
    }
  GNUNET_break(CS_CALLEE_CONNECTED == ch->status);
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Sending PICK_UP message to cadet\n");
  env =
    GNUNET_MQ_msg(mppm, GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_PHONE_PICK_UP);
  GNUNET_MQ_send(ch->mq, env);
  GNUNET_SERVICE_client_continue(line->client);
}


static void
clean_up_channel(struct Channel *ch)
{
  struct Line *line = ch->line;
  struct GNUNET_MQ_Envelope *env;
  struct ClientPhoneHangupMessage *hup;

  switch (ch->status)
    {
    case CS_CALLEE_INIT:
    case CS_CALLEE_SHUTDOWN:
    case CS_CALLER_SHUTDOWN:
      break;

    case CS_CALLEE_RINGING:
    case CS_CALLEE_CONNECTED:
    case CS_CALLER_CALLING:
    case CS_CALLER_CONNECTED:
      if (NULL != line)
        {
          env =
            GNUNET_MQ_msg(hup, GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_HANG_UP);
          hup->cid = ch->cid;
          GNUNET_MQ_send(line->mq, env);
        }
      break;
    }
  if (NULL != line)
    GNUNET_CONTAINER_DLL_remove(line->channel_head, line->channel_tail, ch);
  GNUNET_free(ch);
}


static void
destroy_line_cadet_channels(struct Channel *ch)
{
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Destroying cadet channels\n");
  if (NULL != ch->channel)
    {
      GNUNET_CADET_channel_destroy(ch->channel);
      ch->channel = NULL;
    }
  clean_up_channel(ch);
}


static void
mq_done_finish_caller_shutdown(void *cls)
{
  struct Channel *ch = cls;

  switch (ch->status)
    {
    case CS_CALLEE_INIT:
      GNUNET_break(0);
      break;

    case CS_CALLEE_RINGING:
      GNUNET_break(0);
      break;

    case CS_CALLEE_CONNECTED:
      GNUNET_break(0);
      break;

    case CS_CALLEE_SHUTDOWN:
      destroy_line_cadet_channels(ch);
      break;

    case CS_CALLER_CALLING:
      GNUNET_break(0);
      break;

    case CS_CALLER_CONNECTED:
      GNUNET_break(0);
      break;

    case CS_CALLER_SHUTDOWN:
      destroy_line_cadet_channels(ch);
      break;
    }
}


static void
handle_client_hangup_message(void *cls,
                             const struct ClientPhoneHangupMessage *msg)
{
  struct Line *line = cls;
  struct GNUNET_MQ_Envelope *e;
  struct CadetPhoneHangupMessage *mhum;
  struct Channel *ch;

  for (ch = line->channel_head; NULL != ch; ch = ch->next)
    if (msg->cid == ch->cid)
      break;
  if (NULL == ch)
    {
      /* could have been destroyed asynchronously, ignore message */
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Channel %u not found\n", msg->cid);
      GNUNET_SERVICE_client_continue(line->client);
      return;
    }
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Received HANGUP for channel %u which is in state %d\n",
             msg->cid,
             ch->status);
  switch (ch->status)
    {
    case CS_CALLEE_INIT:
      GNUNET_break(0);
      GNUNET_SERVICE_client_drop(line->client);
      return;

    case CS_CALLEE_RINGING:
      ch->status = CS_CALLEE_SHUTDOWN;
      break;

    case CS_CALLEE_CONNECTED:
      ch->status = CS_CALLEE_SHUTDOWN;
      break;

    case CS_CALLEE_SHUTDOWN:
      /* maybe the other peer closed asynchronously... */
      GNUNET_SERVICE_client_continue(line->client);
      return;

    case CS_CALLER_CALLING:
      ch->status = CS_CALLER_SHUTDOWN;
      break;

    case CS_CALLER_CONNECTED:
      ch->status = CS_CALLER_SHUTDOWN;
      break;

    case CS_CALLER_SHUTDOWN:
      /* maybe the other peer closed asynchronously... */
      GNUNET_SERVICE_client_continue(line->client);
      return;
    }
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Sending HANG_UP message via cadet\n");
  e =
    GNUNET_MQ_msg(mhum, GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_PHONE_HANG_UP);
  GNUNET_MQ_notify_sent(e, &mq_done_finish_caller_shutdown, ch);
  GNUNET_MQ_send(ch->mq, e);
  GNUNET_SERVICE_client_continue(line->client);
}


static void
handle_client_suspend_message(void *cls,
                              const struct ClientPhoneSuspendMessage *msg)
{
  struct Line *line = cls;
  struct GNUNET_MQ_Envelope *e;
  struct CadetPhoneSuspendMessage *mhum;
  struct Channel *ch;

  for (ch = line->channel_head; NULL != ch; ch = ch->next)
    if (msg->cid == ch->cid)
      break;
  if (NULL == ch)
    {
      /* could have been destroyed asynchronously, ignore message */
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Channel %u not found\n", msg->cid);
      GNUNET_SERVICE_client_continue(line->client);
      return;
    }
  if (GNUNET_YES == ch->suspended_local)
    {
      GNUNET_break(0);
      GNUNET_SERVICE_client_drop(line->client);
      return;
    }
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Received SUSPEND for channel %u which is in state %d\n",
             msg->cid,
             ch->status);
  switch (ch->status)
    {
    case CS_CALLEE_INIT:
      GNUNET_break(0);
      GNUNET_SERVICE_client_drop(line->client);
      return;

    case CS_CALLEE_RINGING:
      GNUNET_break(0);
      GNUNET_SERVICE_client_drop(line->client);
      return;

    case CS_CALLEE_CONNECTED:
      ch->suspended_local = GNUNET_YES;
      break;

    case CS_CALLEE_SHUTDOWN:
      /* maybe the other peer closed asynchronously... */
      GNUNET_SERVICE_client_continue(line->client);
      return;

    case CS_CALLER_CALLING:
      GNUNET_break(0);
      GNUNET_SERVICE_client_drop(line->client);
      return;

    case CS_CALLER_CONNECTED:
      ch->suspended_local = GNUNET_YES;
      break;

    case CS_CALLER_SHUTDOWN:
      /* maybe the other peer closed asynchronously... */
      GNUNET_SERVICE_client_continue(line->client);
      return;
    }
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Sending SUSPEND message via cadet\n");
  e =
    GNUNET_MQ_msg(mhum, GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_PHONE_SUSPEND);
  GNUNET_MQ_send(ch->mq, e);
  GNUNET_SERVICE_client_continue(line->client);
}


static void
handle_client_resume_message(void *cls,
                             const struct ClientPhoneResumeMessage *msg)
{
  struct Line *line = cls;
  struct GNUNET_MQ_Envelope *e;
  struct CadetPhoneResumeMessage *mhum;
  struct Channel *ch;

  for (ch = line->channel_head; NULL != ch; ch = ch->next)
    if (msg->cid == ch->cid)
      break;
  if (NULL == ch)
    {
      /* could have been destroyed asynchronously, ignore message */
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Channel %u not found\n", msg->cid);
      GNUNET_SERVICE_client_continue(line->client);
      return;
    }
  if (GNUNET_YES != ch->suspended_local)
    {
      GNUNET_break(0);
      GNUNET_SERVICE_client_drop(line->client);
      return;
    }
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Received RESUME for channel %u which is in state %d\n",
             msg->cid,
             ch->status);
  switch (ch->status)
    {
    case CS_CALLEE_INIT:
      GNUNET_break(0);
      GNUNET_SERVICE_client_drop(line->client);
      return;

    case CS_CALLEE_RINGING:
      GNUNET_break(0);
      GNUNET_SERVICE_client_drop(line->client);
      return;

    case CS_CALLEE_CONNECTED:
      ch->suspended_local = GNUNET_NO;
      break;

    case CS_CALLEE_SHUTDOWN:
      /* maybe the other peer closed asynchronously... */
      GNUNET_SERVICE_client_continue(line->client);
      return;

    case CS_CALLER_CALLING:
      GNUNET_break(0);
      GNUNET_SERVICE_client_drop(line->client);
      return;

    case CS_CALLER_CONNECTED:
      ch->suspended_local = GNUNET_NO;
      break;

    case CS_CALLER_SHUTDOWN:
      /* maybe the other peer closed asynchronously... */
      GNUNET_SERVICE_client_drop(line->client);
      return;
    }
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Sending RESUME message via cadet\n");
  e = GNUNET_MQ_msg(mhum, GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_PHONE_RESUME);
  GNUNET_MQ_send(ch->mq, e);
  GNUNET_SERVICE_client_continue(line->client);
}


static void
channel_audio_sent_notify(void *cls)
{
  struct Channel *ch = cls;

  ch->env = NULL;
}


static int
check_client_audio_message(void *cls, const struct ClientAudioMessage *msg)
{
  (void)cls;
  (void)msg;
  return GNUNET_OK;
}


static void
handle_client_audio_message(void *cls, const struct ClientAudioMessage *msg)
{
  struct Line *line = cls;
  struct CadetAudioMessage *mam;
  struct Channel *ch;
  size_t size;

  size = ntohs(msg->header.size) - sizeof(struct ClientAudioMessage);
  ch = find_channel_by_line(line, msg->cid);
  if (NULL == ch)
    {
      /* could have been destroyed asynchronously, ignore message */
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Channel %u not found\n", msg->cid);
      GNUNET_SERVICE_client_continue(line->client);
      return;
    }

  switch (ch->status)
    {
    case CS_CALLEE_INIT:
    case CS_CALLEE_RINGING:
    case CS_CALLER_CALLING:
      GNUNET_break(0);
      GNUNET_SERVICE_client_drop(line->client);
      return;

    case CS_CALLEE_CONNECTED:
    case CS_CALLER_CONNECTED:
      /* common case, handled below */
      break;

    case CS_CALLEE_SHUTDOWN:
    case CS_CALLER_SHUTDOWN:
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG | GNUNET_ERROR_TYPE_BULK,
                 "Cadet audio channel in shutdown; audio data dropped\n");
      GNUNET_SERVICE_client_continue(line->client);
      return;
    }
  if (GNUNET_YES == ch->suspended_local)
    {
      GNUNET_log(GNUNET_ERROR_TYPE_WARNING,
                 "This channel is suspended locally\n");
      GNUNET_SERVICE_client_drop(line->client);
      return;
    }
  if (NULL != ch->env)
    {
      /* NOTE: we may want to not do this and instead combine the data */
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
                 "Bandwidth insufficient; dropping previous audio data segment\n");
      GNUNET_MQ_send_cancel(ch->env);
      ch->env = NULL;
    }

  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Received %u bytes of AUDIO data from client CID %u\n",
             (unsigned int)size,
             msg->cid);
  ch->env = GNUNET_MQ_msg_extra(mam,
                                size,
                                GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_AUDIO);
  GNUNET_memcpy(&mam[1], &msg[1], size);
  /* FIXME: set options for unreliable transmission */
  GNUNET_MQ_notify_sent(ch->env, &channel_audio_sent_notify, ch);
  GNUNET_MQ_send(ch->mq, ch->env);
  GNUNET_SERVICE_client_continue(line->client);
}


static void
handle_cadet_ring_message(void *cls, const struct CadetPhoneRingMessage *msg)
{
  struct Channel *ch = cls;
  struct Line *line = ch->line;
  struct GNUNET_MQ_Envelope *env;
  struct ClientPhoneRingMessage *cring;
  struct CadetPhoneRingInfoPS rs;

  rs.purpose.purpose = htonl(GNUNET_SIGNATURE_PURPOSE_CONVERSATION_RING);
  rs.purpose.size = htonl(sizeof(struct CadetPhoneRingInfoPS));
  rs.line_port = line->line_port;
  rs.target_peer = my_identity;
  rs.expiration_time = msg->expiration_time;

  if (GNUNET_OK !=
      GNUNET_CRYPTO_ecdsa_verify(GNUNET_SIGNATURE_PURPOSE_CONVERSATION_RING,
                                 &rs.purpose,
                                 &msg->signature,
                                 &msg->caller_id))
    {
      GNUNET_break_op(0);
      destroy_line_cadet_channels(ch);
      return;
    }
  if (0 == GNUNET_TIME_absolute_get_remaining(
        GNUNET_TIME_absolute_ntoh(msg->expiration_time))
      .rel_value_us)
    {
      /* ancient call, replay? */
      GNUNET_break_op(0);
      /* Note that our reliance on time here is awkward; better would be
         to use a more complex challenge-response protocol against
         replay attacks.  Left for future work ;-). */
      destroy_line_cadet_channels(ch);
      return;
    }
  if (CS_CALLEE_INIT != ch->status)
    {
      GNUNET_break_op(0);
      destroy_line_cadet_channels(ch);
      return;
    }
  GNUNET_CADET_receive_done(ch->channel);
  ch->status = CS_CALLEE_RINGING;
  env = GNUNET_MQ_msg(cring, GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_RING);
  cring->cid = ch->cid;
  cring->caller_id = msg->caller_id;
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Sending RING message to client. CID is %u\n",
             (unsigned int)ch->cid);
  GNUNET_MQ_send(line->mq, env);
}


static void
handle_cadet_hangup_message(void *cls,
                            const struct CadetPhoneHangupMessage *message)
{
  struct Channel *ch = cls;
  struct Line *line = ch->line;
  struct GNUNET_MQ_Envelope *env;
  struct ClientPhoneHangupMessage *hup;
  enum ChannelStatus status;
  uint32_t cid;

  (void)message;
  GNUNET_CADET_receive_done(ch->channel);
  cid = ch->cid;
  status = ch->status;
  destroy_line_cadet_channels(ch);
  switch (status)
    {
    case CS_CALLEE_INIT:
      GNUNET_break_op(0);
      return;

    case CS_CALLEE_RINGING:
    case CS_CALLEE_CONNECTED:
      break;

    case CS_CALLEE_SHUTDOWN:
      return;

    case CS_CALLER_CALLING:
    case CS_CALLER_CONNECTED:
      break;

    case CS_CALLER_SHUTDOWN:
      return;
    }
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Sending HANG UP message to client\n");
  env = GNUNET_MQ_msg(hup, GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_HANG_UP);
  hup->cid = cid;
  GNUNET_MQ_send(line->mq, env);
}


static void
handle_cadet_pickup_message(void *cls,
                            const struct CadetPhonePickupMessage *message)
{
  struct Channel *ch = cls;
  struct Line *line = ch->line;
  struct GNUNET_MQ_Envelope *env;
  struct ClientPhonePickedupMessage *pick;

  (void)message;
  GNUNET_CADET_receive_done(ch->channel);
  switch (ch->status)
    {
    case CS_CALLEE_INIT:
    case CS_CALLEE_RINGING:
    case CS_CALLEE_CONNECTED:
      GNUNET_break_op(0);
      destroy_line_cadet_channels(ch);
      return;

    case CS_CALLEE_SHUTDOWN:
      GNUNET_break_op(0);
      destroy_line_cadet_channels(ch);
      return;

    case CS_CALLER_CALLING:
      ch->status = CS_CALLER_CONNECTED;
      break;

    case CS_CALLER_CONNECTED:
      GNUNET_break_op(0);
      return;

    case CS_CALLER_SHUTDOWN:
      GNUNET_break_op(0);
      mq_done_finish_caller_shutdown(ch);
      return;
    }
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Sending PICKED UP message to client\n");
  env =
    GNUNET_MQ_msg(pick, GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_PICKED_UP);
  pick->cid = ch->cid;
  GNUNET_MQ_send(line->mq, env);
}


static void
handle_cadet_suspend_message(void *cls,
                             const struct CadetPhoneSuspendMessage *message)
{
  struct Channel *ch = cls;
  struct Line *line = ch->line;
  struct GNUNET_MQ_Envelope *env;
  struct ClientPhoneSuspendMessage *suspend;

  (void)message;
  GNUNET_CADET_receive_done(ch->channel);
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Suspending channel CID: %u\n", ch->cid);
  switch (ch->status)
    {
    case CS_CALLEE_INIT:
      GNUNET_break_op(0);
      break;

    case CS_CALLEE_RINGING:
      GNUNET_break_op(0);
      break;

    case CS_CALLEE_CONNECTED:
      ch->suspended_remote = GNUNET_YES;
      break;

    case CS_CALLEE_SHUTDOWN:
      return;

    case CS_CALLER_CALLING:
      GNUNET_break_op(0);
      break;

    case CS_CALLER_CONNECTED:
      ch->suspended_remote = GNUNET_YES;
      break;

    case CS_CALLER_SHUTDOWN:
      return;
    }
  env =
    GNUNET_MQ_msg(suspend, GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_SUSPEND);
  suspend->cid = ch->cid;
  GNUNET_MQ_send(line->mq, env);
}


static void
handle_cadet_resume_message(void *cls,
                            const struct CadetPhoneResumeMessage *msg)
{
  struct Channel *ch = cls;
  struct Line *line;
  struct GNUNET_MQ_Envelope *env;
  struct ClientPhoneResumeMessage *resume;

  (void)msg;
  line = ch->line;
  GNUNET_CADET_receive_done(ch->channel);
  if (GNUNET_YES != ch->suspended_remote)
    {
      GNUNET_log(
        GNUNET_ERROR_TYPE_DEBUG,
        "RESUME message received for non-suspended channel, dropping channel.\n");
      destroy_line_cadet_channels(ch);
      return;
    }
  switch (ch->status)
    {
    case CS_CALLEE_INIT:
      GNUNET_break(0);
      break;

    case CS_CALLEE_RINGING:
      GNUNET_break(0);
      break;

    case CS_CALLEE_CONNECTED:
      ch->suspended_remote = GNUNET_NO;
      break;

    case CS_CALLEE_SHUTDOWN:
      return;

    case CS_CALLER_CALLING:
      GNUNET_break(0);
      break;

    case CS_CALLER_CONNECTED:
      ch->suspended_remote = GNUNET_NO;
      break;

    case CS_CALLER_SHUTDOWN:
      return;
    }
  env =
    GNUNET_MQ_msg(resume, GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_RESUME);
  resume->cid = ch->cid;
  GNUNET_MQ_send(line->mq, env);
}


static int
check_cadet_audio_message(void *cls, const struct CadetAudioMessage *msg)
{
  (void)cls;
  (void)msg;
  return GNUNET_OK; /* any payload is fine */
}


static void
handle_cadet_audio_message(void *cls, const struct CadetAudioMessage *msg)
{
  struct Channel *ch = cls;
  size_t msize = ntohs(msg->header.size) - sizeof(struct CadetAudioMessage);
  struct GNUNET_MQ_Envelope *env;
  struct ClientAudioMessage *cam;

  GNUNET_CADET_receive_done(ch->channel);
  if ((GNUNET_YES == ch->suspended_local) ||
      (GNUNET_YES == ch->suspended_remote))
    {
      GNUNET_log(
        GNUNET_ERROR_TYPE_DEBUG,
        "Received %u bytes of AUDIO data on suspended channel CID %u; dropping\n",
        (unsigned int)msize,
        ch->cid);
      return;
    }
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Forwarding %u bytes of AUDIO data to client CID %u\n",
             (unsigned int)msize,
             ch->cid);
  env =
    GNUNET_MQ_msg_extra(cam, msize, GNUNET_MESSAGE_TYPE_CONVERSATION_CS_AUDIO);
  cam->cid = ch->cid;
  GNUNET_memcpy(&cam[1], &msg[1], msize);
  GNUNET_MQ_send(ch->line->mq, env);
}


static void
inbound_end(void *cls, const struct GNUNET_CADET_Channel *channel)
{
  struct Channel *ch = cls;

  GNUNET_assert(channel == ch->channel);
  ch->channel = NULL;
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Channel destroyed by CADET in state %d\n",
             ch->status);
  clean_up_channel(ch);
}


static void
handle_client_call_message(void *cls, const struct ClientCallMessage *msg)
{
  struct Line *line = cls;
  struct Channel *ch = GNUNET_new(struct Channel);
  struct GNUNET_MQ_MessageHandler cadet_handlers[] =
  { GNUNET_MQ_hd_fixed_size(cadet_hangup_message,
                            GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_PHONE_HANG_UP,
                            struct CadetPhoneHangupMessage,
                            ch),
    GNUNET_MQ_hd_fixed_size(cadet_pickup_message,
                            GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_PHONE_PICK_UP,
                            struct CadetPhonePickupMessage,
                            ch),
    GNUNET_MQ_hd_fixed_size(cadet_suspend_message,
                            GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_PHONE_SUSPEND,
                            struct CadetPhoneSuspendMessage,
                            ch),
    GNUNET_MQ_hd_fixed_size(cadet_resume_message,
                            GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_PHONE_RESUME,
                            struct CadetPhoneResumeMessage,
                            ch),
    GNUNET_MQ_hd_var_size(cadet_audio_message,
                          GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_AUDIO,
                          struct CadetAudioMessage,
                          ch),
    GNUNET_MQ_handler_end() };
  struct GNUNET_MQ_Envelope *e;
  struct CadetPhoneRingMessage *ring;
  struct CadetPhoneRingInfoPS rs;

  line->line_port = msg->line_port;
  rs.purpose.purpose = htonl(GNUNET_SIGNATURE_PURPOSE_CONVERSATION_RING);
  rs.purpose.size = htonl(sizeof(struct CadetPhoneRingInfoPS));
  rs.line_port = line->line_port;
  rs.target_peer = msg->target;
  rs.expiration_time =
    GNUNET_TIME_absolute_hton(GNUNET_TIME_relative_to_absolute(RING_TIMEOUT));
  ch->line = line;
  GNUNET_CONTAINER_DLL_insert(line->channel_head, line->channel_tail, ch);
  ch->status = CS_CALLER_CALLING;
  ch->channel = GNUNET_CADET_channel_create(cadet,
                                            ch,
                                            &msg->target,
                                            &msg->line_port,
                                            NULL,
                                            &inbound_end,
                                            cadet_handlers);
  ch->mq = GNUNET_CADET_get_mq(ch->channel);
  e = GNUNET_MQ_msg(ring, GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_PHONE_RING);
  GNUNET_CRYPTO_ecdsa_key_get_public(&msg->caller_id, &ring->caller_id);
  ring->expiration_time = rs.expiration_time;
  GNUNET_assert(GNUNET_OK == GNUNET_CRYPTO_ecdsa_sign(&msg->caller_id,
                                                      &rs.purpose,
                                                      &ring->signature));
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Sending RING message via CADET\n");
  GNUNET_MQ_send(ch->mq, e);
  GNUNET_SERVICE_client_continue(line->client);
}


static void *
inbound_channel(void *cls,
                struct GNUNET_CADET_Channel *channel,
                const struct GNUNET_PeerIdentity *initiator)
{
  struct Line *line = cls;
  struct Channel *ch;

  (void)initiator;
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
             "Received incoming cadet channel on line %p\n",
             line);
  ch = GNUNET_new(struct Channel);
  ch->status = CS_CALLEE_INIT;
  ch->line = line;
  ch->channel = channel;
  ch->mq = GNUNET_CADET_get_mq(ch->channel);
  ch->cid = line->cid_gen++;
  GNUNET_CONTAINER_DLL_insert(line->channel_head, line->channel_tail, ch);
  return ch;
}


static void *
client_connect_cb(void *cls,
                  struct GNUNET_SERVICE_Client *client,
                  struct GNUNET_MQ_Handle *mq)
{
  struct Line *line;

  (void)cls;
  line = GNUNET_new(struct Line);
  line->client = client;
  line->mq = mq;
  return line;
}


static void
client_disconnect_cb(void *cls,
                     struct GNUNET_SERVICE_Client *client,
                     void *app_ctx)
{
  struct Line *line = app_ctx;
  struct Channel *chn;

  (void)cls;
  (void)client;
  GNUNET_log(GNUNET_ERROR_TYPE_DEBUG, "Client disconnected, closing line\n");
  if (NULL != line->port)
    {
      GNUNET_CADET_close_port(line->port);
      line->port = NULL;
    }
  for (struct Channel *ch = line->channel_head; NULL != ch; ch = chn)
    {
      chn = ch->next;
      ch->line = NULL;
      destroy_line_cadet_channels(ch);
    }
  GNUNET_free(line);
}


static void
handle_client_register_message(void *cls,
                               const struct ClientPhoneRegisterMessage *msg)
{
  struct Line *line = cls;
  struct GNUNET_MQ_MessageHandler cadet_handlers[] =
  { GNUNET_MQ_hd_fixed_size(cadet_ring_message,
                            GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_PHONE_RING,
                            struct CadetPhoneRingMessage,
                            NULL),
    GNUNET_MQ_hd_fixed_size(cadet_hangup_message,
                            GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_PHONE_HANG_UP,
                            struct CadetPhoneHangupMessage,
                            NULL),
    GNUNET_MQ_hd_fixed_size(cadet_pickup_message,
                            GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_PHONE_PICK_UP,
                            struct CadetPhonePickupMessage,
                            NULL),
    GNUNET_MQ_hd_fixed_size(cadet_suspend_message,
                            GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_PHONE_SUSPEND,
                            struct CadetPhoneSuspendMessage,
                            NULL),
    GNUNET_MQ_hd_fixed_size(cadet_resume_message,
                            GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_PHONE_RESUME,
                            struct CadetPhoneResumeMessage,
                            NULL),
    GNUNET_MQ_hd_var_size(cadet_audio_message,
                          GNUNET_MESSAGE_TYPE_CONVERSATION_CADET_AUDIO,
                          struct CadetAudioMessage,
                          NULL),
    GNUNET_MQ_handler_end() };

  line->line_port = msg->line_port;
  line->port = GNUNET_CADET_open_port(cadet,
                                      &msg->line_port,
                                      &inbound_channel,
                                      line,
                                      NULL,
                                      &inbound_end,
                                      cadet_handlers);
  if (NULL == line->port)
    {
      GNUNET_log(GNUNET_ERROR_TYPE_WARNING,
                 _("Could not open line, port %s already in use!\n"),
                 GNUNET_h2s(&msg->line_port));
      GNUNET_SERVICE_client_drop(line->client);
      return;
    }
  GNUNET_SERVICE_client_continue(line->client);
}


static void
do_shutdown(void *cls)
{
  (void)cls;
  if (NULL != cadet)
    {
      GNUNET_CADET_disconnect(cadet);
      cadet = NULL;
    }
}


static void
run(void *cls,
    const struct GNUNET_CONFIGURATION_Handle *c,
    struct GNUNET_SERVICE_Handle *service)
{
  (void)cls;
  (void)service;
  cfg = c;
  GNUNET_assert(GNUNET_OK ==
                GNUNET_CRYPTO_get_peer_identity(cfg, &my_identity));
  cadet = GNUNET_CADET_connect(cfg);
  if (NULL == cadet)
    {
      GNUNET_break(0);
      GNUNET_SCHEDULER_shutdown();
      return;
    }
  GNUNET_SCHEDULER_add_shutdown(&do_shutdown, NULL);
}


GNUNET_SERVICE_MAIN(
  "conversation",
  GNUNET_SERVICE_OPTION_NONE,
  &run,
  &client_connect_cb,
  &client_disconnect_cb,
  NULL,
  GNUNET_MQ_hd_fixed_size(client_register_message,
                          GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_REGISTER,
                          struct ClientPhoneRegisterMessage,
                          NULL),
  GNUNET_MQ_hd_fixed_size(client_pickup_message,
                          GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_PICK_UP,
                          struct ClientPhonePickupMessage,
                          NULL),
  GNUNET_MQ_hd_fixed_size(client_suspend_message,
                          GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_SUSPEND,
                          struct ClientPhoneSuspendMessage,
                          NULL),
  GNUNET_MQ_hd_fixed_size(client_resume_message,
                          GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_RESUME,
                          struct ClientPhoneResumeMessage,
                          NULL),
  GNUNET_MQ_hd_fixed_size(client_hangup_message,
                          GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_HANG_UP,
                          struct ClientPhoneHangupMessage,
                          NULL),
  GNUNET_MQ_hd_fixed_size(client_call_message,
                          GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_CALL,
                          struct ClientCallMessage,
                          NULL),
  GNUNET_MQ_hd_var_size(client_audio_message,
                        GNUNET_MESSAGE_TYPE_CONVERSATION_CS_AUDIO,
                        struct ClientAudioMessage,
                        NULL),
  GNUNET_MQ_handler_end());


/* end of gnunet-service-conversation.c */