/*
  This file is part of GNUnet.
  (C) 2013 Christian Grothoff (and other contributing authors)

  GNUnet is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published
  by the Free Software Foundation; either version 3, or (at your
  option) any later version.

  GNUnet is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with GNUnet; see the file COPYING.  If not, write to the
  Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  Boston, MA 02111-1307, USA.
*/
/**
 * @file conversation/gnunet-service-conversation.c
 * @brief conversation service implementation
 * @author Simon Dieterle
 * @author Andreas Fuchs
 * @author Christian Grothoff
 */
#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_mesh_service.h"
#include "gnunet_conversation_service.h"
#include "conversation.h"


/**
 * How long is our signature on a call valid?  Needs to be long enough for time zone
 * differences and network latency to not matter.  No strong need for it to be short,
 * but we simply like all signatures to eventually expire.
 */
#define RING_TIMEOUT GNUNET_TIME_UNIT_DAYS


/**
 * The possible connection status
 */
enum LineStatus
{
  /**
   * We are waiting for incoming calls.
   */
  LS_CALLEE_LISTEN,

  /**
   * Our phone is ringing, waiting for the client to pick up.
   */
  LS_CALLEE_RINGING,

  /**
   * We are talking!
   */
  LS_CALLEE_CONNECTED,

  /**
   * We're in shutdown, sending hangup messages before cleaning up.
   */
  LS_CALLEE_SHUTDOWN,

  /**
   * We are waiting for the phone to be picked up.
   */
  LS_CALLER_CALLING,

  /**
   * We are talking!
   */
  LS_CALLER_CONNECTED,

  /**
   * We're in shutdown, sending hangup messages before cleaning up.
   */
  LS_CALLER_SHUTDOWN
};


/**
 * A line connects a local client with a mesh tunnel (or, if it is an
 * open line, is waiting for a mesh tunnel).
 */
struct Line
{
  /**
   * Kept in a DLL.
   */
  struct Line *next;

  /**
   * Kept in a DLL.
   */
  struct Line *prev;

  /**
   * Handle for the reliable tunnel (contol data)
   */
  struct GNUNET_MESH_Tunnel *tunnel_reliable;

  /**
   * Handle for unreliable tunnel (audio data)
   */
  struct GNUNET_MESH_Tunnel *tunnel_unreliable;

  /**
   * Transmit handle for pending audio messages
   */
  struct GNUNET_MESH_TransmitHandle *unreliable_mth;

  /**
   * Message queue for control messages
   */
  struct GNUNET_MQ_Handle *reliable_mq;

  /**
   * Handle to the line client.
   */
  struct GNUNET_SERVER_Client *client;

  /**
   * Target of the line, if we are the caller.
   */
  struct GNUNET_PeerIdentity target;

  /**
   * Temporary buffer for audio data.
   */
  void *audio_data;

  /**
   * Number of bytes in @e audio_data.
   */
  size_t audio_size;

  /**
   * Our line number.
   */
  uint32_t local_line;

  /**
   * Remote line number.
   */
  uint32_t remote_line;

  /**
   * Current status of this line.
   */
  enum LineStatus status;

};


/**
 * Our configuration.
 */
static const struct GNUNET_CONFIGURATION_Handle *cfg;

/**
 * Notification context containing all connected clients.
 */
static struct GNUNET_SERVER_NotificationContext *nc;

/**
 * Handle for mesh
 */
static struct GNUNET_MESH_Handle *mesh;

/**
 * Identity of this peer.
 */
static struct GNUNET_PeerIdentity my_identity;

/**
 * Head of DLL of active lines.
 */
static struct Line *lines_head;

/**
 * Tail of DLL of active lines.
 */
static struct Line *lines_tail;

/**
 * Counter for generating local line numbers.
 * FIXME: randomize generation in the future
 * to eliminate information leakage.
 */
static uint32_t local_line_cnt;


/**
 * Function to register a phone.
 *
 * @param cls closure, NULL
 * @param client the client from which the message is
 * @param message the message from the client
 */
static void
handle_client_register_message (void *cls,
                                struct GNUNET_SERVER_Client *client,
                                const struct GNUNET_MessageHeader *message)
{
  const struct ClientPhoneRegisterMessage *msg;
  struct Line *line;

  msg = (struct ClientPhoneRegisterMessage *) message;
  line = GNUNET_SERVER_client_get_user_context (client, struct Line);
  if (NULL != line)
  {
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  line = GNUNET_new (struct Line);
  line->client = client;
  GNUNET_SERVER_notification_context_add (nc, client);
  GNUNET_SERVER_client_set_user_context (client, line);
  GNUNET_CONTAINER_DLL_insert (lines_head,
                               lines_tail,
                               line);
  line->local_line = ntohl (msg->line);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Function to handle a pickup request message from the client
 *
 * @param cls closure, NULL
 * @param client the client from which the message is
 * @param message the message from the client
 */
static void
handle_client_pickup_message (void *cls,
                              struct GNUNET_SERVER_Client *client,
                              const struct GNUNET_MessageHeader *message)
{
  const struct ClientPhonePickupMessage *msg;
  struct GNUNET_MQ_Envelope *e;
  struct MeshPhonePickupMessage *mppm;
  const char *meta;
  struct Line *line;
  size_t len;

  msg = (struct ClientPhonePickupMessage *) message;
  meta = (const char *) &msg[1];
  len = ntohs (msg->header.size) - sizeof (struct ClientPhonePickupMessage);
  if ( (0 == len) ||
       ('\0' != meta[len - 1]) )
  {
    meta = NULL;
    len = 0;
  }
  line = GNUNET_SERVER_client_get_user_context (client, struct Line);
  if (NULL == line)
  {
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  switch (line->status)
  {
  case LS_CALLEE_LISTEN:
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Ignoring client's PICKUP message, caller has HUNG UP already\n");
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
    break;
  case LS_CALLEE_RINGING:
    line->status = LS_CALLEE_CONNECTED;
    break;
  case LS_CALLEE_CONNECTED:
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  case LS_CALLEE_SHUTDOWN:
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Ignoring client's PICKUP message, line is in SHUTDOWN\n");
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
    break;
  case LS_CALLER_CALLING:
  case LS_CALLER_CONNECTED:
  case LS_CALLER_SHUTDOWN:
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  line->status = LS_CALLEE_CONNECTED;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sending PICK_UP message to mesh with meta data `%s'\n",
              meta);
  e = GNUNET_MQ_msg_extra (mppm,
                           len,
                           GNUNET_MESSAGE_TYPE_CONVERSATION_MESH_PHONE_PICK_UP);
  memcpy (&mppm[1], meta, len);
  GNUNET_MQ_send (line->reliable_mq, e);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Destroy the mesh tunnels of a line.
 *
 * @param line line to shutdown tunnels of
 */
static void
destroy_line_mesh_tunnels (struct Line *line)
{
  struct GNUNET_MESH_Tunnel *t;

  if (NULL != line->reliable_mq)
  {
    GNUNET_MQ_destroy (line->reliable_mq);
    line->reliable_mq = NULL;
  }
  if (NULL != line->unreliable_mth)
  {
    GNUNET_MESH_notify_transmit_ready_cancel (line->unreliable_mth);
    line->unreliable_mth = NULL;
  }
  if (NULL != (t = line->tunnel_unreliable))
  {
    line->tunnel_unreliable = NULL;
    GNUNET_MESH_tunnel_destroy (t);
  }
  if (NULL != (t = line->tunnel_reliable))
  {
    line->tunnel_reliable = NULL;
    GNUNET_MESH_tunnel_destroy (t);
  }
}


/**
 * We are done signalling shutdown to the other peer.  Close down
 * (or reset) the line.
 *
 * @param cls the `struct Line` to reset/terminate
 */
static void
mq_done_finish_caller_shutdown (void *cls)
{
  struct Line *line = cls;

  switch (line->status)
  {
  case LS_CALLEE_LISTEN:
    GNUNET_break (0);
    break;
  case LS_CALLEE_RINGING:
    GNUNET_break (0);
    break;
  case LS_CALLEE_CONNECTED:
    GNUNET_break (0);
    break;
  case LS_CALLEE_SHUTDOWN:
    line->status = LS_CALLEE_LISTEN;
    destroy_line_mesh_tunnels (line);
    return;
  case LS_CALLER_CALLING:
    line->status = LS_CALLER_SHUTDOWN;
    break;
  case LS_CALLER_CONNECTED:
    line->status = LS_CALLER_SHUTDOWN;
    break;
  case LS_CALLER_SHUTDOWN:
    destroy_line_mesh_tunnels (line);
    break;
  }
}


/**
 * Function to handle a hangup request message from the client
 *
 * @param cls closure, NULL
 * @param client the client from which the message is
 * @param message the message from the client
 */
static void
handle_client_hangup_message (void *cls,
                              struct GNUNET_SERVER_Client *client,
                              const struct GNUNET_MessageHeader *message)
{
  const struct ClientPhoneHangupMessage *msg;
  struct GNUNET_MQ_Envelope *e;
  struct MeshPhoneHangupMessage *mhum;
  const char *meta;
  struct Line *line;
  size_t len;

  msg = (struct ClientPhoneHangupMessage *) message;
  meta = (const char *) &msg[1];
  len = ntohs (msg->header.size) - sizeof (struct ClientPhoneHangupMessage);
  if ( (0 == len) ||
       ('\0' != meta[len - 1]) )
  {
    meta = NULL;
    len = 0;
  }
  line = GNUNET_SERVER_client_get_user_context (client, struct Line);
  if (NULL == line)
  {
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  switch (line->status)
  {
  case LS_CALLEE_LISTEN:
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
    return;
  case LS_CALLEE_RINGING:
    line->status = LS_CALLEE_SHUTDOWN;
    break;
  case LS_CALLEE_CONNECTED:
    line->status = LS_CALLEE_SHUTDOWN;
    break;
  case LS_CALLEE_SHUTDOWN:
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
    return;
  case LS_CALLER_CALLING:
    line->status = LS_CALLER_SHUTDOWN;
    break;
  case LS_CALLER_CONNECTED:
    line->status = LS_CALLER_SHUTDOWN;
    break;
  case LS_CALLER_SHUTDOWN:
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
    return;
  }
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sending HANG_UP message via mesh with meta data `%s'\n",
              meta);
  e = GNUNET_MQ_msg_extra (mhum,
                           len,
                           GNUNET_MESSAGE_TYPE_CONVERSATION_MESH_PHONE_HANG_UP);
  memcpy (&mhum[1], meta, len);
  GNUNET_MQ_notify_sent (e,
                         &mq_done_finish_caller_shutdown,
                         line);
  GNUNET_MQ_send (line->reliable_mq, e);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Function to handle call request the client
 *
 * @param cls closure, NULL
 * @param client the client from which the message is
 * @param message the message from the client
 */
static void
handle_client_call_message (void *cls,
                            struct GNUNET_SERVER_Client *client,
                            const struct GNUNET_MessageHeader *message)
{
  const struct ClientCallMessage *msg;
  struct Line *line;
  struct GNUNET_MQ_Envelope *e;
  struct MeshPhoneRingMessage *ring;

  msg = (struct ClientCallMessage *) message;
  line = GNUNET_SERVER_client_get_user_context (client, struct Line);
  if (NULL != line)
  {
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  line = GNUNET_new (struct Line);
  line->client = client;
  GNUNET_SERVER_client_set_user_context (client, line);
  GNUNET_SERVER_notification_context_add (nc, client);
  line->target = msg->target;
  GNUNET_CONTAINER_DLL_insert (lines_head,
                               lines_tail,
                               line);
  line->remote_line = ntohl (msg->line);
  line->status = LS_CALLER_CALLING;
  line->tunnel_reliable = GNUNET_MESH_tunnel_create (mesh,
                                                     line,
                                                     &msg->target,
                                                     GNUNET_APPLICATION_TYPE_CONVERSATION_CONTROL,
                                                     GNUNET_NO,
                                                     GNUNET_YES);
  line->reliable_mq = GNUNET_MESH_mq_create (line->tunnel_reliable);
  line->local_line = local_line_cnt++;
  e = GNUNET_MQ_msg (ring, GNUNET_MESSAGE_TYPE_CONVERSATION_MESH_PHONE_RING);
  ring->purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_CONVERSATION_RING);
  ring->purpose.size = htonl (sizeof (struct GNUNET_PeerIdentity) * 2 +
                              sizeof (struct GNUNET_TIME_AbsoluteNBO) +
                              sizeof (struct GNUNET_CRYPTO_EccSignaturePurpose) +
                              sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey));
  GNUNET_CRYPTO_ecdsa_key_get_public (&msg->caller_id,
                                                  &ring->caller_id);
  ring->remote_line = msg->line;
  ring->source_line = line->local_line;
  ring->target = msg->target;
  ring->source = my_identity;
  ring->expiration_time = GNUNET_TIME_absolute_hton (GNUNET_TIME_relative_to_absolute (RING_TIMEOUT));
  GNUNET_CRYPTO_ecdsa_sign (&msg->caller_id,
                          &ring->purpose,
                          &ring->signature);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sending RING message via mesh\n");
  GNUNET_MQ_send (line->reliable_mq, e);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * Transmit audio data via unreliable mesh channel.
 *
 * @param cls the `struct Line` we are transmitting for
 * @param size number of bytes available in @a buf
 * @param buf where to copy the data
 * @return number of bytes copied to @a buf
 */
static size_t
transmit_line_audio (void *cls,
                     size_t size,
                     void *buf)
{
  struct Line *line = cls;
  struct MeshAudioMessage *mam = buf;

  line->unreliable_mth = NULL;
  if ( (NULL == buf) ||
       (size < sizeof (struct MeshAudioMessage) + line->audio_size) )
    {
    /* eh, other error handling? */
    return 0;
  }
  mam->header.size = htons (sizeof (struct MeshAudioMessage) + line->audio_size);
  mam->header.type = htons (GNUNET_MESSAGE_TYPE_CONVERSATION_MESH_AUDIO);
  mam->remote_line = htonl (line->remote_line);
  memcpy (&mam[1], line->audio_data, line->audio_size);
  GNUNET_free (line->audio_data);
  line->audio_data = NULL;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sending %u bytes of audio data via mesh\n",
              line->audio_size);
  return sizeof (struct MeshAudioMessage) + line->audio_size;
}


/**
 * Function to handle audio data from the client
 *
 * @param cls closure, NULL
 * @param client the client from which the message is
 * @param message the message from the client
 */
static void
handle_client_audio_message (void *cls,
                             struct GNUNET_SERVER_Client *client,
                             const struct GNUNET_MessageHeader *message)
{
  const struct ClientAudioMessage *msg;
  struct Line *line;
  size_t size;

  size = ntohs (message->size) - sizeof (struct ClientAudioMessage);
  msg = (struct ClientAudioMessage *) message;
  line = GNUNET_SERVER_client_get_user_context (client, struct Line);
  if (NULL == line)
  {
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  }
  switch (line->status)
  {
  case LS_CALLEE_LISTEN:
    /* could be OK if the line just was closed by the other side */
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Audio data dropped, channel is down\n");
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
    break;
  case LS_CALLEE_RINGING:
  case LS_CALLER_CALLING:
    GNUNET_break (0);
    GNUNET_SERVER_receive_done (client, GNUNET_SYSERR);
    return;
  case LS_CALLEE_CONNECTED:
  case LS_CALLER_CONNECTED:
    /* common case, handled below */
    break;
  case LS_CALLEE_SHUTDOWN:
  case LS_CALLER_SHUTDOWN:
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG | GNUNET_ERROR_TYPE_BULK,
                "Mesh audio channel in shutdown; audio data dropped\n");
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
    return;
  }
  if (NULL == line->tunnel_unreliable)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO | GNUNET_ERROR_TYPE_BULK,
                _("Mesh audio channel not ready; audio data dropped\n"));
    GNUNET_SERVER_receive_done (client, GNUNET_OK);
    return;
  }
  if (NULL != line->unreliable_mth)
  {
    /* 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 with %u bytes\n",
                (unsigned int) line->audio_size);
    GNUNET_MESH_notify_transmit_ready_cancel (line->unreliable_mth);
    line->unreliable_mth = NULL;
    GNUNET_free (line->audio_data);
    line->audio_data = NULL;
  }
  line->audio_size = size;
  line->audio_data = GNUNET_malloc (line->audio_size);
  memcpy (line->audio_data,
          &msg[1],
          size);
  line->unreliable_mth = GNUNET_MESH_notify_transmit_ready (line->tunnel_unreliable,
                                                            GNUNET_NO,
                                                            GNUNET_TIME_UNIT_FOREVER_REL,
                                                            sizeof (struct MeshAudioMessage)
                                                            + line->audio_size,
                                                            &transmit_line_audio,
                                                            line);
  GNUNET_SERVER_receive_done (client, GNUNET_OK);
}


/**
 * We are done signalling shutdown to the other peer.
 * Destroy the tunnel.
 *
 * @param cls the `struct GNUNET_MESH_tunnel` to destroy
 */
static void
mq_done_destroy_tunnel (void *cls)
{
  struct GNUNET_MESH_Tunnel *tunnel = cls;

  GNUNET_MESH_tunnel_destroy (tunnel);
}


/**
 * Function to handle a ring message incoming over mesh
 *
 * @param cls closure, NULL
 * @param tunnel the tunnel over which the message arrived
 * @param tunnel_ctx the tunnel context, can be NULL
 * @param message the incoming message
 * @return #GNUNET_OK
 */
static int
handle_mesh_ring_message (void *cls,
                          struct GNUNET_MESH_Tunnel *tunnel,
                          void **tunnel_ctx,
                          const struct GNUNET_MessageHeader *message)
{
  const struct MeshPhoneRingMessage *msg;
  struct Line *line;
  struct GNUNET_MQ_Envelope *e;
  struct MeshPhoneBusyMessage *busy;
  struct ClientPhoneRingMessage cring;

  msg = (const struct MeshPhoneRingMessage *) message;
  if ( (msg->purpose.size != htonl (sizeof (struct GNUNET_PeerIdentity) * 2 +
                                    sizeof (struct GNUNET_TIME_AbsoluteNBO) +
                                    sizeof (struct GNUNET_CRYPTO_EccSignaturePurpose) +
                                    sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey))) ||
       (GNUNET_OK !=
        GNUNET_CRYPTO_ecdsa_verify (GNUNET_SIGNATURE_PURPOSE_CONVERSATION_RING,
                                  &msg->purpose,
                                  &msg->signature,
                                  &msg->caller_id)) )
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  for (line = lines_head; NULL != line; line = line->next)
    if ( (line->local_line == ntohl (msg->remote_line)) &&
         (LS_CALLEE_LISTEN == line->status) )
      break;
  if (NULL == line)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                _("No available phone for incoming call on line %u, sending BUSY signal\n"),
                ntohl (msg->remote_line));
    e = GNUNET_MQ_msg (busy, GNUNET_MESSAGE_TYPE_CONVERSATION_MESH_PHONE_BUSY);
    GNUNET_MQ_notify_sent (e,
                           &mq_done_destroy_tunnel,
                           tunnel);
    GNUNET_MQ_send (line->reliable_mq, e);
    GNUNET_MESH_receive_done (tunnel); /* needed? */
    return GNUNET_OK;
  }
  line->status = LS_CALLEE_RINGING;
  line->remote_line = ntohl (msg->source_line);
  line->tunnel_reliable = tunnel;
  line->reliable_mq = GNUNET_MESH_mq_create (line->tunnel_reliable);
  *tunnel_ctx = line;
  cring.header.type = htons (GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_RING);
  cring.header.size = htons (sizeof (cring));
  cring.reserved = htonl (0);
  cring.caller_id = msg->caller_id;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sending RING message to client\n");
  GNUNET_SERVER_notification_context_unicast (nc,
                                              line->client,
                                              &cring.header,
                                              GNUNET_NO);
  GNUNET_MESH_receive_done (tunnel);
  return GNUNET_OK;
}


/**
 * Function to handle a hangup message incoming over mesh
 *
 * @param cls closure, NULL
 * @param tunnel the tunnel over which the message arrived
 * @param tunnel_ctx the tunnel context, can be NULL
 * @param message the incoming message
 * @return #GNUNET_OK
 */
static int
handle_mesh_hangup_message (void *cls,
                            struct GNUNET_MESH_Tunnel *tunnel,
                            void **tunnel_ctx,
                            const struct GNUNET_MessageHeader *message)
{
  struct Line *line = *tunnel_ctx;
  const struct MeshPhoneHangupMessage *msg;
  const char *reason;
  size_t len = ntohs (message->size) - sizeof (struct MeshPhoneHangupMessage);
  char buf[len + sizeof (struct ClientPhoneHangupMessage)];
  struct ClientPhoneHangupMessage *hup;

  msg = (const struct MeshPhoneHangupMessage *) message;
  len = ntohs (msg->header.size) - sizeof (struct MeshPhoneHangupMessage);
  reason = (const char *) &msg[1];
  if ( (0 == len) ||
       ('\0' != reason[len - 1]) )
  {
    reason = NULL;
    len = 0;
  }
  if (NULL == line)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "HANGUP message received for non-existing line, dropping tunnel.\n");
    return GNUNET_SYSERR;
  }
  *tunnel_ctx = NULL;
  switch (line->status)
  {
  case LS_CALLEE_LISTEN:
    GNUNET_break (0);
    return GNUNET_SYSERR;
  case LS_CALLEE_RINGING:
    line->status = LS_CALLEE_LISTEN;
    destroy_line_mesh_tunnels (line);
    break;
  case LS_CALLEE_CONNECTED:
    line->status = LS_CALLEE_LISTEN;
    destroy_line_mesh_tunnels (line);
    break;
  case LS_CALLEE_SHUTDOWN:
    line->status = LS_CALLEE_LISTEN;
    destroy_line_mesh_tunnels (line);
    return GNUNET_OK;
  case LS_CALLER_CALLING:
    line->status = LS_CALLER_SHUTDOWN;
    mq_done_finish_caller_shutdown (line);
    break;
  case LS_CALLER_CONNECTED:
    line->status = LS_CALLER_SHUTDOWN;
    mq_done_finish_caller_shutdown (line);
    break;
  case LS_CALLER_SHUTDOWN:
    mq_done_finish_caller_shutdown (line);
    return GNUNET_OK;
  }
  hup = (struct ClientPhoneHangupMessage *) buf;
  hup->header.size = sizeof (buf);
  hup->header.type = htons (GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_HANG_UP);
  memcpy (&hup[1], reason, len);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sending HANG UP message to client with reason `%s'\n",
              reason);
  GNUNET_SERVER_notification_context_unicast (nc,
                                              line->client,
                                              &hup->header,
                                              GNUNET_NO);
  GNUNET_MESH_receive_done (tunnel);
  return GNUNET_OK;
}


/**
 * Function to handle a pickup message incoming over mesh
 *
 * @param cls closure, NULL
 * @param tunnel the tunnel over which the message arrived
 * @param tunnel_ctx the tunnel context, can be NULL
 * @param message the incoming message
 * @return #GNUNET_OK
 */
static int
handle_mesh_pickup_message (void *cls,
                            struct GNUNET_MESH_Tunnel *tunnel,
                            void **tunnel_ctx,
                            const struct GNUNET_MessageHeader *message)
{
  const struct MeshPhonePickupMessage *msg;
  struct Line *line = *tunnel_ctx;
  const char *metadata;
  size_t len = ntohs (message->size) - sizeof (struct MeshPhonePickupMessage);
  char buf[len + sizeof (struct ClientPhonePickupMessage)];
  struct ClientPhonePickupMessage *pick;

  msg = (const struct MeshPhonePickupMessage *) message;
  len = ntohs (msg->header.size) - sizeof (struct MeshPhonePickupMessage);
  metadata = (const char *) &msg[1];
  if ( (0 == len) ||
       ('\0' != metadata[len - 1]) )
  {
    metadata = NULL;
    len = 0;
  }
  if (NULL == line)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "PICKUP message received for non-existing line, dropping tunnel.\n");
    return GNUNET_SYSERR;
  }
  GNUNET_MESH_receive_done (tunnel);
  switch (line->status)
  {
  case LS_CALLEE_LISTEN:
    GNUNET_break (0);
    return GNUNET_SYSERR;
  case LS_CALLEE_RINGING:
  case LS_CALLEE_CONNECTED:
    GNUNET_break_op (0);
    destroy_line_mesh_tunnels (line);
    line->status = LS_CALLEE_LISTEN;
    return GNUNET_SYSERR;
  case LS_CALLEE_SHUTDOWN:
    GNUNET_break_op (0);
    line->status = LS_CALLEE_LISTEN;
    destroy_line_mesh_tunnels (line);
    break;
  case LS_CALLER_CALLING:
    line->status = LS_CALLER_CONNECTED;
    break;
  case LS_CALLER_CONNECTED:
    GNUNET_break_op (0);
    return GNUNET_OK;
  case LS_CALLER_SHUTDOWN:
    GNUNET_break_op (0);
    mq_done_finish_caller_shutdown (line);
    return GNUNET_SYSERR;
  }
  pick = (struct ClientPhonePickupMessage *) buf;
  pick->header.size = sizeof (buf);
  pick->header.type = htons (GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_PICKED_UP);
  memcpy (&pick[1], metadata, len);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sending PICKED UP message to client with metadata `%s'\n",
              metadata);
  GNUNET_SERVER_notification_context_unicast (nc,
                                              line->client,
                                              &pick->header,
                                              GNUNET_NO);
  line->tunnel_unreliable = GNUNET_MESH_tunnel_create (mesh,
                                                       line,
                                                       &line->target,
                                                       GNUNET_APPLICATION_TYPE_CONVERSATION_AUDIO,
                                                       GNUNET_YES,
                                                       GNUNET_NO);
  if (NULL == line->tunnel_unreliable)
  {
    GNUNET_break (0);
  }
  return GNUNET_OK;
}


/**
 * Function to handle a busy message incoming over mesh
 *
 * @param cls closure, NULL
 * @param tunnel the tunnel over which the message arrived
 * @param tunnel_ctx the tunnel context, can be NULL
 * @param message the incoming message
 * @return #GNUNET_OK
 */
static int
handle_mesh_busy_message (void *cls,
                          struct GNUNET_MESH_Tunnel *tunnel,
                          void **tunnel_ctx,
                          const struct GNUNET_MessageHeader *message)
{
  struct Line *line = *tunnel_ctx;
  struct ClientPhoneBusyMessage busy;

  if (NULL == line)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "HANGUP message received for non-existing line, dropping tunnel.\n");
    return GNUNET_SYSERR;
  }
  busy.header.size = sizeof (busy);
  busy.header.type = htons (GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_BUSY);
  GNUNET_MESH_receive_done (tunnel);
  *tunnel_ctx = NULL;
  switch (line->status)
  {
  case LS_CALLEE_LISTEN:
    GNUNET_break (0);
    return GNUNET_SYSERR;
  case LS_CALLEE_RINGING:
    GNUNET_break_op (0);
    break;
  case LS_CALLEE_CONNECTED:
    GNUNET_break_op (0);
    break;
  case LS_CALLEE_SHUTDOWN:
    GNUNET_break_op (0);
    break;
  case LS_CALLER_CALLING:
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Sending BUSY message to client\n");
    GNUNET_SERVER_notification_context_unicast (nc,
                                                line->client,
                                                &busy.header,
                                                GNUNET_NO);
    line->status = LS_CALLER_SHUTDOWN;
    mq_done_finish_caller_shutdown (line);
    break;
  case LS_CALLER_CONNECTED:
    GNUNET_break_op (0);
    line->status = LS_CALLER_SHUTDOWN;
    mq_done_finish_caller_shutdown (line);
    break;
  case LS_CALLER_SHUTDOWN:
    GNUNET_break_op (0);
    mq_done_finish_caller_shutdown (line);
    break;
  }
  return GNUNET_OK;
}


/**
 * Function to handle an audio message incoming over mesh
 *
 * @param cls closure, NULL
 * @param tunnel the tunnel over which the message arrived
 * @param tunnel_ctx the tunnel context, can be NULL
 * @param message the incoming message
 * @return #GNUNET_OK
 */
static int
handle_mesh_audio_message (void *cls,
                           struct GNUNET_MESH_Tunnel *tunnel,
                           void **tunnel_ctx,
                           const struct GNUNET_MessageHeader *message)
{
  const struct MeshAudioMessage *msg;
  struct Line *line = *tunnel_ctx;
  struct GNUNET_PeerIdentity sender;
  size_t msize = ntohs (message->size) - sizeof (struct MeshAudioMessage);
  char buf[msize + sizeof (struct ClientAudioMessage)];
  struct ClientAudioMessage *cam;
  const union GNUNET_MESH_TunnelInfo *info;

  msg = (const struct MeshAudioMessage *) message;
  if (NULL == line)
  {
    info = GNUNET_MESH_tunnel_get_info (tunnel,
                                        GNUNET_MESH_OPTION_PEER);
    if (NULL == info)
    {
      GNUNET_break (0);
      return GNUNET_OK;
    }
    sender = info->peer;
    for (line = lines_head; NULL != line; line = line->next)
      if ( (line->local_line == ntohl (msg->remote_line)) &&
           (LS_CALLEE_CONNECTED == line->status) &&
           (0 == memcmp (&line->target,
                         &sender,
                         sizeof (struct GNUNET_PeerIdentity))) &&
           (NULL == line->tunnel_unreliable) )
        break;
    if (NULL == line)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Received AUDIO data for non-existing line %u, dropping.\n",
                  ntohl (msg->remote_line));
      return GNUNET_SYSERR;
    }
    line->tunnel_unreliable = tunnel;
    *tunnel_ctx = line;
  }
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Forwarding %u bytes of AUDIO data to client\n",
              msize);
  cam = (struct ClientAudioMessage *) buf;
  cam->header.size = htons (sizeof (buf));
  cam->header.type = htons (GNUNET_MESSAGE_TYPE_CONVERSATION_CS_AUDIO);
  memcpy (&cam[1], &msg[1], msize);
  GNUNET_SERVER_notification_context_unicast (nc,
                                              line->client,
                                              &cam->header,
                                              GNUNET_YES);
  GNUNET_MESH_receive_done (tunnel);
  return GNUNET_OK;
}


/**
 * Method called whenever another peer has added us to a tunnel
 * the other peer initiated.
 *
 * @param cls closure
 * @param tunnel new handle to the tunnel
 * @param initiator peer that started the tunnel
 * @param port port
 * @return initial tunnel context for the tunnel (can be NULL -- that's not an error)
 */
static void *
inbound_tunnel (void *cls,
                struct GNUNET_MESH_Tunnel *tunnel,
		const struct GNUNET_PeerIdentity *initiator,
                uint32_t port)
{
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
	      _("Received incoming tunnel on port %u\n"),
              (unsigned int) port);
  return NULL;
}


/**
 * Function called whenever an inbound tunnel is destroyed.  Should clean up
 * any associated state.
 *
 * @param cls closure (set from #GNUNET_MESH_connect)
 * @param tunnel connection to the other end (henceforth invalid)
 * @param tunnel_ctx place where local state associated
 *                   with the tunnel is stored
 */
static void
inbound_end (void *cls,
             const struct GNUNET_MESH_Tunnel *tunnel,
	     void *tunnel_ctx)
{
  struct Line *line = tunnel_ctx;
  struct ClientPhoneHangupMessage hup;

  if (NULL == line)
    return;
  if (line->tunnel_unreliable == tunnel)
  {
    if (NULL != line->unreliable_mth)
    {
      GNUNET_MESH_notify_transmit_ready_cancel (line->unreliable_mth);
      line->unreliable_mth = NULL;
    }
    line->tunnel_unreliable = NULL;
    return;
  }
  if (line->tunnel_reliable != tunnel)
    return;
  line->tunnel_reliable = NULL;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Mesh tunnel destroyed by mesh\n");
  hup.header.size = sizeof (hup);
  hup.header.type = htons (GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_HANG_UP);
  switch (line->status)
  {
  case LS_CALLEE_LISTEN:
    GNUNET_break (0);
    break;
  case LS_CALLEE_RINGING:
  case LS_CALLEE_CONNECTED:
    GNUNET_SERVER_notification_context_unicast (nc,
                                                line->client,
                                                &hup.header,
                                                GNUNET_NO);
    line->status = LS_CALLEE_LISTEN;
    break;
  case LS_CALLEE_SHUTDOWN:
    line->status = LS_CALLEE_LISTEN;
    break;
  case LS_CALLER_CALLING:
  case LS_CALLER_CONNECTED:
    GNUNET_SERVER_notification_context_unicast (nc,
                                                line->client,
                                                &hup.header,
                                                GNUNET_NO);
    break;
  case LS_CALLER_SHUTDOWN:
    break;
  }
  destroy_line_mesh_tunnels (line);
}


/**
 * A client disconnected.  Remove all of its data structure entries.
 *
 * @param cls closure, NULL
 * @param client identification of the client
 */
static void
handle_client_disconnect (void *cls,
                          struct GNUNET_SERVER_Client *client)
{
  struct Line *line;

  if (NULL == client)
    return;
  line = GNUNET_SERVER_client_get_user_context (client, struct Line);
  if (NULL == line)
    return;
  GNUNET_SERVER_client_set_user_context (client, NULL);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Client disconnected, closing line\n");
  GNUNET_CONTAINER_DLL_remove (lines_head,
                               lines_tail,
                               line);
  destroy_line_mesh_tunnels (line);
  GNUNET_free_non_null (line->audio_data);
  GNUNET_free (line);
}


/**
 * Shutdown nicely
 *
 * @param cls closure, NULL
 * @param tc the task context
 */
static void
do_shutdown (void *cls,
             const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  if (NULL != mesh)
  {
    GNUNET_MESH_disconnect (mesh);
    mesh = NULL;
  }
  if (NULL != nc)
  {
    GNUNET_SERVER_notification_context_destroy (nc);
    nc = NULL;
  }
}


/**
 * Main function that will be run by the scheduler.
 *
 * @param cls closure
 * @param server server handle
 * @param c configuration
 */
static void
run (void *cls,
     struct GNUNET_SERVER_Handle *server,
     const struct GNUNET_CONFIGURATION_Handle *c)
{
  static const struct GNUNET_SERVER_MessageHandler server_handlers[] = {
    {&handle_client_register_message, NULL,
     GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_REGISTER,
     sizeof (struct ClientPhoneRegisterMessage)},
    {&handle_client_pickup_message, NULL,
     GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_PICK_UP,
     0},
    {&handle_client_hangup_message, NULL,
     GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_HANG_UP,
     0},
    {&handle_client_call_message, NULL,
     GNUNET_MESSAGE_TYPE_CONVERSATION_CS_PHONE_CALL,
     0},
    {&handle_client_audio_message, NULL,
     GNUNET_MESSAGE_TYPE_CONVERSATION_CS_AUDIO,
     0},
    {NULL, NULL, 0, 0}
  };
  static struct GNUNET_MESH_MessageHandler mesh_handlers[] = {
    {&handle_mesh_ring_message,
     GNUNET_MESSAGE_TYPE_CONVERSATION_MESH_PHONE_RING,
     sizeof (struct MeshPhoneRingMessage)},
    {&handle_mesh_hangup_message,
     GNUNET_MESSAGE_TYPE_CONVERSATION_MESH_PHONE_HANG_UP,
     0},
    {&handle_mesh_pickup_message,
     GNUNET_MESSAGE_TYPE_CONVERSATION_MESH_PHONE_PICK_UP,
     0},
    {&handle_mesh_busy_message,
     GNUNET_MESSAGE_TYPE_CONVERSATION_MESH_PHONE_BUSY,
     sizeof (struct MeshPhoneBusyMessage)},
    {&handle_mesh_audio_message, GNUNET_MESSAGE_TYPE_CONVERSATION_MESH_AUDIO,
     0},
    {NULL, 0, 0}
  };
  static uint32_t ports[] = {
    GNUNET_APPLICATION_TYPE_CONVERSATION_CONTROL,
    GNUNET_APPLICATION_TYPE_CONVERSATION_AUDIO,
    0
  };

  cfg = c;
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_CRYPTO_get_peer_identity (cfg,
                                                  &my_identity));
  mesh = GNUNET_MESH_connect (cfg,
			      NULL,
			      &inbound_tunnel,
			      &inbound_end,
                              mesh_handlers,
                              ports);

  if (NULL == mesh)
  {
    GNUNET_break (0);
    GNUNET_SCHEDULER_shutdown ();
    return;
  }
  nc = GNUNET_SERVER_notification_context_create (server, 16);
  GNUNET_SERVER_add_handlers (server, server_handlers);
  GNUNET_SERVER_disconnect_notify (server, &handle_client_disconnect, NULL);
  GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_FOREVER_REL,
                                &do_shutdown,
				NULL);
}


/**
 * The main function for the conversation service.
 *
 * @param argc number of arguments from the command line
 * @param argv command line arguments
 * @return 0 ok, 1 on error
 */
int
main (int argc,
      char *const *argv)
{
  return (GNUNET_OK ==
	  GNUNET_SERVICE_run (argc, argv,
                              "conversation",
                              GNUNET_SERVICE_OPTION_NONE,
			      &run, NULL)) ? 0 : 1;
}

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