core_unreal.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2013 Digium, Inc.
 *
 * Richard Mudgett <[email protected]>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*!
 * \file
 * \brief Unreal channel derivatives framework for channel drivers like local channels.
 *
 * \author Richard Mudgett <[email protected]>
 *
 * See Also:
 * \arg \ref AstCREDITS
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include "asterisk/causes.h"
#include "asterisk/channel.h"
#include "asterisk/stasis_channels.h"
#include "asterisk/pbx.h"
#include "asterisk/musiconhold.h"
#include "asterisk/astobj2.h"
#include "asterisk/bridge.h"
#include "asterisk/core_unreal.h"
#include "asterisk/stream.h"

static unsigned int name_sequence = 0;

void ast_unreal_lock_all(struct ast_unreal_pvt *p, struct ast_channel **outchan, struct ast_channel **outowner)
{
   struct ast_channel *chan = NULL;
   struct ast_channel *owner = NULL;

   ao2_lock(p);
   for (;;) {
      if (p->chan) {
         chan = p->chan;
         ast_channel_ref(chan);
      }
      if (p->owner) {
         owner = p->owner;
         ast_channel_ref(owner);
      }
      ao2_unlock(p);

      /* if we don't have both channels, then this is very easy */
      if (!owner || !chan) {
         if (owner) {
            ast_channel_lock(owner);
         } else if(chan) {
            ast_channel_lock(chan);
         }
      } else {
         /* lock both channels first, then get the pvt lock */
         ast_channel_lock_both(chan, owner);
      }
      ao2_lock(p);

      /* Now that we have all the locks, validate that nothing changed */
      if (p->owner != owner || p->chan != chan) {
         if (owner) {
            ast_channel_unlock(owner);
            owner = ast_channel_unref(owner);
         }
         if (chan) {
            ast_channel_unlock(chan);
            chan = ast_channel_unref(chan);
         }
         continue;
      }

      break;
   }
   *outowner = p->owner;
   *outchan = p->chan;
}

/* Called with ast locked */
int ast_unreal_setoption(struct ast_channel *ast, int option, void *data, int datalen)
{
   int res = 0;
   struct ast_unreal_pvt *p;
   struct ast_channel *otherchan = NULL;
   ast_chan_write_info_t *write_info;
   char *info_data;

   if (option != AST_OPTION_CHANNEL_WRITE) {
      return -1;
   }

   write_info = data;

   if (write_info->version != AST_CHAN_WRITE_INFO_T_VERSION) {
      ast_log(LOG_ERROR, "The chan_write_info_t type has changed, and this channel hasn't been updated!\n");
      return -1;
   }

   info_data = write_info->data;
   if (!strcmp(write_info->function, "CHANNEL")) {
      if (!strncasecmp(info_data, "hangup_handler_", 15)) {
         /* Block CHANNEL(hangup_handler_xxx) writes to the other unreal channel. */
         return 0;
      }

      /* Crossover the accountcode and peeraccount to cross the unreal bridge. */
      if (!strcasecmp(info_data, "accountcode")) {
         info_data = "peeraccount";
      } else if (!strcasecmp(info_data, "peeraccount")) {
         info_data = "accountcode";
      }
   }

   /* get the tech pvt */
   if (!(p = ast_channel_tech_pvt(ast))) {
      return -1;
   }
   ao2_ref(p, 1);
   ast_channel_unlock(ast); /* Held when called, unlock before locking another channel */

   /* get the channel we are supposed to write to */
   ao2_lock(p);
   otherchan = (write_info->chan == p->owner) ? p->chan : p->owner;
   if (!otherchan || otherchan == write_info->chan) {
      res = -1;
      otherchan = NULL;
      ao2_unlock(p);
      goto setoption_cleanup;
   }
   ast_channel_ref(otherchan);

   /* clear the pvt lock before grabbing the channel */
   ao2_unlock(p);

   ast_channel_lock(otherchan);
   res = write_info->write_fn(otherchan, write_info->function, info_data, write_info->value);
   ast_channel_unlock(otherchan);

setoption_cleanup:
   ao2_ref(p, -1);
   if (otherchan) {
      ast_channel_unref(otherchan);
   }
   ast_channel_lock(ast); /* Lock back before we leave */
   return res;
}

/* Called with ast locked */
int ast_unreal_queryoption(struct ast_channel *ast, int option, void *data, int *datalen)
{
   struct ast_unreal_pvt *p;
   struct ast_channel *peer;
   struct ast_channel *other;
   int res = 0;

   if (option != AST_OPTION_T38_STATE) {
      /* AST_OPTION_T38_STATE is the only supported option at this time */
      return -1;
   }

   /* for some reason the channel is not locked in channel.c when this function is called */
   if (!(p = ast_channel_tech_pvt(ast))) {
      return -1;
   }

   ao2_lock(p);
   other = AST_UNREAL_IS_OUTBOUND(ast, p) ? p->owner : p->chan;
   if (!other) {
      ao2_unlock(p);
      return -1;
   }
   ast_channel_ref(other);
   ao2_unlock(p);
   ast_channel_unlock(ast); /* Held when called, unlock before locking another channel */

   peer = ast_channel_bridge_peer(other);
   if (peer) {
      res = ast_channel_queryoption(peer, option, data, datalen, 0);
      ast_channel_unref(peer);
   }
   ast_channel_unref(other);
   ast_channel_lock(ast); /* Lock back before we leave */

   return res;
}

/*!
 * \brief queue a frame onto either the p->owner or p->chan
 *
 * \note the ast_unreal_pvt MUST have it's ref count bumped before entering this function and
 * decremented after this function is called.  This is a side effect of the deadlock
 * avoidance that is necessary to lock 2 channels and a tech_pvt.  Without a ref counted
 * ast_unreal_pvt, it is impossible to guarantee it will not be destroyed by another thread
 * during deadlock avoidance.
 */
static int unreal_queue_frame(struct ast_unreal_pvt *p, int isoutbound, struct ast_frame *f,
   struct ast_channel *us, int us_locked)
{
   struct ast_channel *other;

   /* Recalculate outbound channel */
   other = isoutbound ? p->owner : p->chan;
   if (!other) {
      return 0;
   }

   /* do not queue media frames if a generator is on both unreal channels */
   if (us
      && (f->frametype == AST_FRAME_VOICE || f->frametype == AST_FRAME_VIDEO)
      && ast_channel_generator(us)
      && ast_channel_generator(other)) {
      return 0;
   }

   /* grab a ref on the channel before unlocking the pvt,
    * other can not go away from us now regardless of locking */
   ast_channel_ref(other);
   if (us && us_locked) {
      ast_channel_unlock(us);
   }
   ao2_unlock(p);

   if (f->frametype == AST_FRAME_CONTROL && f->subclass.integer == AST_CONTROL_RINGING) {
      ast_setstate(other, AST_STATE_RINGING);
   }
   ast_queue_frame(other, f);

   other = ast_channel_unref(other);
   if (us && us_locked) {
      ast_channel_lock(us);
   }
   ao2_lock(p);

   return 0;
}

int ast_unreal_answer(struct ast_channel *ast)
{
   struct ast_unreal_pvt *p = ast_channel_tech_pvt(ast);
   int isoutbound;
   int res = -1;

   if (!p) {
      return -1;
   }

   ao2_ref(p, 1);
   ao2_lock(p);
   isoutbound = AST_UNREAL_IS_OUTBOUND(ast, p);
   if (isoutbound) {
      /* Pass along answer since somebody answered us */
      struct ast_frame answer = { AST_FRAME_CONTROL, { AST_CONTROL_ANSWER } };

      res = unreal_queue_frame(p, isoutbound, &answer, ast, 1);
   } else {
      ast_log(LOG_WARNING, "Huh?  %s is being asked to answer?\n",
         ast_channel_name(ast));
   }
   ao2_unlock(p);
   ao2_ref(p, -1);
   return res;
}

/*!
 * \internal
 * \brief Check and optimize out the unreal channels between bridges.
 * \since 12.0.0
 *
 * \param ast Channel writing a frame into the unreal channels.
 * \param p Unreal channel private.
 *
 * \note It is assumed that ast is locked.
 * \note It is assumed that p is locked.
 *
 * \retval 0 if unreal channels were not optimized out.
 * \retval non-zero if unreal channels were optimized out.
 */
static int got_optimized_out(struct ast_channel *ast, struct ast_unreal_pvt *p)
{
   int res = 0;

   /* Do a few conditional checks early on just to see if this optimization is possible */
   if (ast_test_flag(p, AST_UNREAL_NO_OPTIMIZATION) || !p->chan || !p->owner) {
      return res;
   }

   if (ast == p->owner) {
      res = ast_bridge_unreal_optimize_out(p->owner, p->chan, p);
   } else if (ast == p->chan) {
      res = ast_bridge_unreal_optimize_out(p->chan, p->owner, p);
   }

   return res;
}

struct ast_frame  *ast_unreal_read(struct ast_channel *ast)
{
   return &ast_null_frame;
}

int ast_unreal_write(struct ast_channel *ast, struct ast_frame *f)
{
   return ast_unreal_write_stream(ast, -1, f);
}

int ast_unreal_write_stream(struct ast_channel *ast, int stream_num, struct ast_frame *f)
{
   struct ast_unreal_pvt *p = ast_channel_tech_pvt(ast);
   int res = -1;

   if (!p) {
      return -1;
   }

   /* If we are told to write a frame with a type that has no corresponding
    * stream on the channel then drop it.
    */
   if (f->frametype == AST_FRAME_VOICE) {
      if (!ast_channel_get_default_stream(ast, AST_MEDIA_TYPE_AUDIO)) {
         return 0;
      }
   } else if (f->frametype == AST_FRAME_VIDEO ||
      (f->frametype == AST_FRAME_CONTROL && f->subclass.integer == AST_CONTROL_VIDUPDATE)) {
      if (!ast_channel_get_default_stream(ast, AST_MEDIA_TYPE_VIDEO)) {
         return 0;
      }
   }

   /* Update the frame to reflect the stream */
   f->stream_num = stream_num;

   /* Just queue for delivery to the other side */
   ao2_ref(p, 1);
   ao2_lock(p);
   switch (f->frametype) {
   case AST_FRAME_VOICE:
   case AST_FRAME_VIDEO:
      if (got_optimized_out(ast, p)) {
         break;
      }
      /* fall through */
   default:
      res = unreal_queue_frame(p, AST_UNREAL_IS_OUTBOUND(ast, p), f, ast, 1);
      break;
   }
   ao2_unlock(p);
   ao2_ref(p, -1);

   return res;
}

int ast_unreal_fixup(struct ast_channel *oldchan, struct ast_channel *newchan)
{
   struct ast_unreal_pvt *p = ast_channel_tech_pvt(newchan);
   struct ast_bridge *bridge_owner;
   struct ast_bridge *bridge_chan;

   if (!p) {
      return -1;
   }

   ao2_lock(p);

   if ((p->owner != oldchan) && (p->chan != oldchan)) {
      ast_log(LOG_WARNING, "Old channel %p wasn't %p or %p\n", oldchan, p->owner, p->chan);
      ao2_unlock(p);
      return -1;
   }
   if (p->owner == oldchan) {
      p->owner = newchan;
   } else {
      p->chan = newchan;
   }

   if (ast_check_hangup(newchan) || !p->owner || !p->chan) {
      ao2_unlock(p);
      return 0;
   }

   /* Do not let a masquerade cause an unreal channel to be bridged to itself! */
   bridge_owner = ast_channel_internal_bridge(p->owner);
   bridge_chan = ast_channel_internal_bridge(p->chan);
   if (bridge_owner && bridge_owner == bridge_chan) {
      ast_log(LOG_WARNING, "You can not bridge an unreal channel (%s) to itself!\n",
         ast_channel_name(newchan));
      ao2_unlock(p);
      ast_queue_hangup(newchan);
      return -1;
   }

   ao2_unlock(p);
   return 0;
}

/*!
 * \internal
 * \brief Queue up a frame representing the indication as a control frame.
 * \since 12.0.0
 *
 * \param p Unreal private structure.
 * \param ast Channel indicating the condition.
 * \param condition What is being indicated.
 * \param data Extra data.
 * \param datalen Length of extra data.
 *
 * \retval 0 on success.
 * \retval AST_T38_REQUEST_PARMS if successful and condition is AST_CONTROL_T38_PARAMETERS.
 * \retval -1 on error.
 */
static int unreal_queue_indicate(struct ast_unreal_pvt *p, struct ast_channel *ast, int condition, const void *data, size_t datalen)
{
   int res = 0;
   int isoutbound;

   ao2_lock(p);
   /*
    * Block -1 stop tones events if we are to be optimized out.  We
    * don't need a flurry of these events on an unreal channel chain
    * when initially connected to slow the optimization process.
    */
   if (0 <= condition || ast_test_flag(p, AST_UNREAL_NO_OPTIMIZATION)) {
      struct ast_frame f = {
         .frametype = AST_FRAME_CONTROL,
         .subclass.integer = condition,
         .data.ptr = (void *) data,
         .datalen = datalen,
      };

      isoutbound = AST_UNREAL_IS_OUTBOUND(ast, p);
      res = unreal_queue_frame(p, isoutbound, &f, ast, 1);
      if (!res
         && condition == AST_CONTROL_T38_PARAMETERS
         && datalen == sizeof(struct ast_control_t38_parameters)) {
         const struct ast_control_t38_parameters *parameters = data;

         if (parameters->request_response == AST_T38_REQUEST_PARMS) {
            res = AST_T38_REQUEST_PARMS;
         }
      }
   } else {
      ast_debug(4, "Blocked indication %d\n", condition);
   }
   ao2_unlock(p);

   return res;
}

/*!
 * \internal
 * \brief Handle COLP and redirecting conditions.
 * \since 12.0.0
 *
 * \param p Unreal private structure.
 * \param ast Channel indicating the condition.
 * \param condition What is being indicated.
 *
 * \retval 0 on success.
 * \retval -1 on error.
 */
static int unreal_colp_redirect_indicate(struct ast_unreal_pvt *p, struct ast_channel *ast, int condition)
{
   struct ast_channel *my_chan;
   struct ast_channel *my_owner;
   struct ast_channel *this_channel;
   struct ast_channel *the_other_channel;
   int isoutbound;
   int res = 0;
   unsigned char frame_data[1024];
   struct ast_frame f = {
      .frametype = AST_FRAME_CONTROL,
      .subclass.integer = condition,
      .data.ptr = frame_data,
   };

   /*
    * A connected line update frame may only contain a partial
    * amount of data, such as just a source, or just a ton, and not
    * the full amount of information.  However, the collected
    * information is all stored in the outgoing channel's
    * connectedline structure, so when receiving a connected line
    * update on an outgoing unreal channel, we need to transmit the
    * collected connected line information instead of whatever
    * happens to be in this control frame.  The same applies for
    * redirecting information, which is why it is handled here as
    * well.
    */
   ast_channel_unlock(ast);
   ast_unreal_lock_all(p, &my_chan, &my_owner);
   isoutbound = AST_UNREAL_IS_OUTBOUND(ast, p);
   if (isoutbound) {
      this_channel = p->chan;
      the_other_channel = p->owner;
   } else {
      this_channel = p->owner;
      the_other_channel = p->chan;
   }
   if (the_other_channel) {
      if (condition == AST_CONTROL_CONNECTED_LINE) {
         ast_connected_line_copy_to_caller(ast_channel_caller(the_other_channel),
            ast_channel_connected(this_channel));
         f.datalen = ast_connected_line_build_data(frame_data, sizeof(frame_data),
            ast_channel_connected(this_channel), NULL);
      } else {
         f.datalen = ast_redirecting_build_data(frame_data, sizeof(frame_data),
            ast_channel_redirecting(this_channel), NULL);
      }
   }
   if (my_chan) {
      ast_channel_unlock(my_chan);
      ast_channel_unref(my_chan);
   }
   if (my_owner) {
      ast_channel_unlock(my_owner);
      ast_channel_unref(my_owner);
   }
   if (the_other_channel) {
      res = unreal_queue_frame(p, isoutbound, &f, ast, 0);
   }
   ao2_unlock(p);
   ast_channel_lock(ast);

   return res;
}

/*!
 * \internal
 * \brief Handle stream topology change request.
 * \since 16.12.0
 * \since 17.6.0
 *
 * \param p Unreal private structure.
 * \param ast Channel indicating the condition.
 * \param topology The requested topology.
 *
 * \retval 0 on success.
 * \retval -1 on error.
 */
static int unreal_colp_stream_topology_request_change(struct ast_unreal_pvt *p, struct ast_channel *ast, const struct ast_stream_topology *topology)
{
   struct ast_stream_topology *this_channel_topology;
   struct ast_stream_topology *the_other_channel_topology;
   int i;
   struct ast_stream *stream;
   struct ast_channel *my_chan;
   struct ast_channel *my_owner;
   struct ast_channel *this_channel;
   struct ast_channel *the_other_channel;
   int res = 0;

   this_channel_topology = ast_stream_topology_clone(topology);
   if (!this_channel_topology) {
      return -1;
   }

   the_other_channel_topology = ast_stream_topology_clone(topology);
   if (!the_other_channel_topology) {
      ast_stream_topology_free(this_channel_topology);
      return -1;
   }

   /* We swap the stream state on the other channel because it is as if the channel is
    * connected to an external endpoint, so the perspective changes.
    */
   for (i = 0; i < ast_stream_topology_get_count(the_other_channel_topology); ++i) {
      stream = ast_stream_topology_get_stream(the_other_channel_topology, i);

      if (ast_stream_get_state(stream) == AST_STREAM_STATE_RECVONLY) {
         ast_stream_set_state(stream, AST_STREAM_STATE_SENDONLY);
      } else if (ast_stream_get_state(stream) == AST_STREAM_STATE_SENDONLY) {
         ast_stream_set_state(stream, AST_STREAM_STATE_RECVONLY);
      }
   }

   ast_channel_unlock(ast);
   ast_unreal_lock_all(p, &my_chan, &my_owner);
   if (AST_UNREAL_IS_OUTBOUND(ast, p)) {
      this_channel = p->chan;
      the_other_channel = p->owner;
   } else {
      this_channel = p->owner;
      the_other_channel = p->chan;
   }
   if (this_channel) {
      ast_channel_set_stream_topology(this_channel, this_channel_topology);
      ast_queue_control(this_channel, AST_CONTROL_STREAM_TOPOLOGY_CHANGED);
   }
   if (the_other_channel) {
      ast_channel_set_stream_topology(the_other_channel, the_other_channel_topology);
      ast_channel_stream_topology_changed_externally(the_other_channel);
   }
   if (my_chan) {
      ast_channel_unlock(my_chan);
      ast_channel_unref(my_chan);
   }
   if (my_owner) {
      ast_channel_unlock(my_owner);
      ast_channel_unref(my_owner);
   }
   ao2_unlock(p);
   ast_channel_lock(ast);

   return res;
}

int ast_unreal_indicate(struct ast_channel *ast, int condition, const void *data, size_t datalen)
{
   struct ast_unreal_pvt *p = ast_channel_tech_pvt(ast);
   int res = 0;
   struct ast_channel *chan = NULL;
   struct ast_channel *owner = NULL;
   const struct ast_control_t38_parameters *parameters;

   if (!p) {
      return -1;
   }

   ao2_ref(p, 1); /* ref for unreal_queue_frame */

   switch (condition) {
   case AST_CONTROL_MASQUERADE_NOTIFY:
      /*
       * Always block this because this is the channel being
       * masqueraded; not anything down the chain.
       */
      break;
   case AST_CONTROL_CONNECTED_LINE:
   case AST_CONTROL_REDIRECTING:
      res = unreal_colp_redirect_indicate(p, ast, condition);
      break;
   case AST_CONTROL_HOLD:
      if (ast_test_flag(p, AST_UNREAL_MOH_INTERCEPT)) {
         ast_moh_start(ast, data, NULL);
         break;
      }
      res = unreal_queue_indicate(p, ast, condition, data, datalen);
      break;
   case AST_CONTROL_UNHOLD:
      if (ast_test_flag(p, AST_UNREAL_MOH_INTERCEPT)) {
         ast_moh_stop(ast);
         break;
      }
      res = unreal_queue_indicate(p, ast, condition, data, datalen);
      break;
   case AST_CONTROL_RINGING:
      /* Don't queue ringing frames if the channel is not in a "ring" state. Otherwise,
       * the real channel on the other end will likely start a playtones generator. It is
       * possible that this playtones generator will never be stopped under certain
       * circumstances.
       */
      if (ast_channel_state(ast) == AST_STATE_RING) {
         res = unreal_queue_indicate(p, ast, condition, data, datalen);
      } else {
         res = -1;
      }
      break;
   case AST_CONTROL_PVT_CAUSE_CODE:
      /* Return -1 so that asterisk core will correctly set up hangupcauses. */
      unreal_queue_indicate(p, ast, condition, data, datalen);
      res = -1;
      break;
   case AST_CONTROL_STREAM_TOPOLOGY_REQUEST_CHANGE:
      if (ast_channel_is_multistream(ast)) {
         res = unreal_colp_stream_topology_request_change(p, ast, data);
      }
      break;
   case AST_CONTROL_T38_PARAMETERS:
      parameters = data;
      if (parameters->request_response == AST_T38_NEGOTIATED) {
         struct ast_stream *stream;
         struct ast_stream_topology *new_topology;

         stream = ast_stream_alloc("local_fax", AST_MEDIA_TYPE_IMAGE);
         if (!stream) {
            ast_log(LOG_ERROR, "Failed to allocate memory for stream.\n");
            res = -1;
            break;
         }
         new_topology = ast_stream_topology_alloc();
         if (!new_topology) {
            ast_log(LOG_ERROR, "Failed to allocate memory for stream topology.\n");
            ast_free(stream);
            res = -1;
            break;
         }
         ast_stream_topology_append_stream(new_topology, stream);

         /*
          * Lock both parts of the local channel so we can store their topologies and replace them with
          * one that has a stream with type IMAGE. We can just hold the reference on the unreal_pvt
          * structure and bump it, then steal the ref later when we are restoring the topology.
          *
          * We use ast_unreal_lock_all here because we don't know if the ;1 or ;2 side will get the
          * signaling and we need to be sure that the locking order is the same to prevent possible
          * deadlocks.
          */
         ast_channel_unlock(ast);
         ast_unreal_lock_all(p, &chan, &owner);

         if (owner) {
            p->owner_old_topology = ao2_bump(ast_channel_get_stream_topology(owner));
            ast_channel_set_stream_topology(owner, new_topology);
         }

         if (chan) {
            p->chan_old_topology = ao2_bump(ast_channel_get_stream_topology(chan));

            /* Bump the ref for new_topology, since it will be used by both sides of the local channel */
            ao2_ref(new_topology, +1);
            ast_channel_set_stream_topology(chan, new_topology);
         }

         ao2_unlock(p);
         ast_channel_lock(ast);
      } else if (parameters->request_response == AST_T38_TERMINATED) {
         /*
          * Lock both parts of the local channel so we can restore their topologies to the original.
          * The topology should be on the unreal_pvt structure, with a ref that we can steal. Same
          * conditions as above.
          */
         ast_channel_unlock(ast);
         ast_unreal_lock_all(p, &chan, &owner);

         if (owner) {
            ast_channel_set_stream_topology(owner, p->owner_old_topology);
            p->owner_old_topology = NULL;
         }

         if (chan) {
            ast_channel_set_stream_topology(chan, p->chan_old_topology);
            p->chan_old_topology = NULL;
         }

         ao2_unlock(p);
         ast_channel_lock(ast);
      }

      /*
       * We unlock ast_unreal_pvt in the above conditionals since there's no way to
       * tell if it's been unlocked already or not when we get to this point, but
       * if either of these are not NULL, we know that they are locked and need to
       * unlock them.
       */
      if (owner) {
         ast_channel_unlock(owner);
         ast_channel_unref(owner);
      }

      if (chan) {
         ast_channel_unlock(chan);
         ast_channel_unref(chan);
      }
      /* Fall through for all T38 conditions */
   default:
      res = unreal_queue_indicate(p, ast, condition, data, datalen);
      break;
   }

   ao2_ref(p, -1);
   return res;
}

int ast_unreal_digit_begin(struct ast_channel *ast, char digit)
{
   struct ast_unreal_pvt *p = ast_channel_tech_pvt(ast);
   int res = -1;
   struct ast_frame f = { AST_FRAME_DTMF_BEGIN, };
   int isoutbound;

   if (!p) {
      return -1;
   }

   ao2_ref(p, 1); /* ref for unreal_queue_frame */
   ao2_lock(p);
   isoutbound = AST_UNREAL_IS_OUTBOUND(ast, p);
   f.subclass.integer = digit;
   res = unreal_queue_frame(p, isoutbound, &f, ast, 0);
   ao2_unlock(p);
   ao2_ref(p, -1);

   return res;
}

int ast_unreal_digit_end(struct ast_channel *ast, char digit, unsigned int duration)
{
   struct ast_unreal_pvt *p = ast_channel_tech_pvt(ast);
   int res = -1;
   struct ast_frame f = { AST_FRAME_DTMF_END, };
   int isoutbound;

   if (!p) {
      return -1;
   }

   ao2_ref(p, 1); /* ref for unreal_queue_frame */
   ao2_lock(p);
   isoutbound = AST_UNREAL_IS_OUTBOUND(ast, p);
   f.subclass.integer = digit;
   f.len = duration;
   res = unreal_queue_frame(p, isoutbound, &f, ast, 0);
   ao2_unlock(p);
   ao2_ref(p, -1);

   return res;
}

int ast_unreal_sendtext(struct ast_channel *ast, const char *text)
{
   struct ast_unreal_pvt *p = ast_channel_tech_pvt(ast);
   int res = -1;
   struct ast_frame f = { AST_FRAME_TEXT, };
   int isoutbound;

   if (!p) {
      return -1;
   }

   ao2_ref(p, 1); /* ref for unreal_queue_frame */
   ao2_lock(p);
   isoutbound = AST_UNREAL_IS_OUTBOUND(ast, p);
   f.data.ptr = (char *) text;
   f.datalen = strlen(text) + 1;
   res = unreal_queue_frame(p, isoutbound, &f, ast, 0);
   ao2_unlock(p);
   ao2_ref(p, -1);
   return res;
}

int ast_unreal_sendhtml(struct ast_channel *ast, int subclass, const char *data, int datalen)
{
   struct ast_unreal_pvt *p = ast_channel_tech_pvt(ast);
   int res = -1;
   struct ast_frame f = { AST_FRAME_HTML, };
   int isoutbound;

   if (!p) {
      return -1;
   }

   ao2_ref(p, 1); /* ref for unreal_queue_frame */
   ao2_lock(p);
   isoutbound = AST_UNREAL_IS_OUTBOUND(ast, p);
   f.subclass.integer = subclass;
   f.data.ptr = (char *)data;
   f.datalen = datalen;
   res = unreal_queue_frame(p, isoutbound, &f, ast, 0);
   ao2_unlock(p);
   ao2_ref(p, -1);

   return res;
}

void ast_unreal_call_setup(struct ast_channel *semi1, struct ast_channel *semi2)
{
   struct ast_var_t *varptr;
   struct ast_var_t *clone_var;

   ast_channel_stage_snapshot(semi2);

   /*
    * Note that cid_num and cid_name aren't passed in the
    * ast_channel_alloc calls in ast_unreal_new_channels().  It's
    * done here instead.
    */
   ast_party_redirecting_copy(ast_channel_redirecting(semi2), ast_channel_redirecting(semi1));

   ast_party_dialed_copy(ast_channel_dialed(semi2), ast_channel_dialed(semi1));

   /* Crossover the CallerID and conected-line to cross the unreal bridge. */
   ast_connected_line_copy_to_caller(ast_channel_caller(semi2), ast_channel_connected(semi1));
   ast_connected_line_copy_from_caller(ast_channel_connected(semi2), ast_channel_caller(semi1));

   ast_channel_language_set(semi2, ast_channel_language(semi1));
   ast_channel_musicclass_set(semi2, ast_channel_musicclass(semi1));
   ast_channel_parkinglot_set(semi2, ast_channel_parkinglot(semi1));

   /* Crossover the accountcode and peeraccount to cross the unreal bridge. */
   ast_channel_accountcode_set(semi2, ast_channel_peeraccount(semi1));
   ast_channel_peeraccount_set(semi2, ast_channel_accountcode(semi1));

   ast_channel_cc_params_init(semi2, ast_channel_get_cc_config_params(semi1));

   /*
    * Make sure we inherit the AST_CAUSE_ANSWERED_ELSEWHERE if it's
    * set on the queue/dial call request in the dialplan.
    */
   if (ast_channel_hangupcause(semi1) == AST_CAUSE_ANSWERED_ELSEWHERE) {
      ast_channel_hangupcause_set(semi2, AST_CAUSE_ANSWERED_ELSEWHERE);
   }

   /*
    * Copy the channel variables from the semi1 channel to the
    * outgoing channel.
    *
    * Note that due to certain assumptions, they MUST be in the
    * same order.
    */
   AST_LIST_TRAVERSE(ast_channel_varshead(semi1), varptr, entries) {
      clone_var = ast_var_assign(varptr->name, varptr->value);
      if (clone_var) {
         AST_LIST_INSERT_TAIL(ast_channel_varshead(semi2), clone_var, entries);
         ast_channel_publish_varset(semi2, ast_var_full_name(clone_var),
            ast_var_value(clone_var));
      }
   }
   ast_channel_datastore_inherit(semi1, semi2);

   ast_channel_stage_snapshot_done(semi2);
}

int ast_unreal_channel_push_to_bridge(struct ast_channel *ast, struct ast_bridge *bridge, unsigned int flags)
{
   struct ast_bridge_features *features;
   struct ast_channel *chan;
   struct ast_channel *owner;
   ast_callid bridge_callid;
   RAII_VAR(struct ast_unreal_pvt *, p, NULL, ao2_cleanup);

   ast_bridge_lock(bridge);
   bridge_callid = bridge->callid;
   ast_bridge_unlock(bridge);

   {
      SCOPED_CHANNELLOCK(lock, ast);
      p = ast_channel_tech_pvt(ast);
      if (!p) {
         return -1;
      }
      ao2_ref(p, +1);
   }

   {
      SCOPED_AO2LOCK(lock, p);
      chan = p->chan;
      if (!chan) {
         return -1;
      }

      owner = p->owner;
      if (!owner) {
         return -1;
      }

      ast_channel_ref(chan);
      ast_channel_ref(owner);
   }

   if (bridge_callid) {
      ast_callid chan_callid;
      ast_callid owner_callid;

      /* chan side call ID setting */
      ast_channel_lock(chan);

      chan_callid = ast_channel_callid(chan);
      if (!chan_callid) {
         ast_channel_callid_set(chan, bridge_callid);
      }
      ast_channel_unlock(chan);

      /* owner side call ID setting */
      ast_channel_lock(owner);

      owner_callid = ast_channel_callid(owner);
      if (!owner_callid) {
         ast_channel_callid_set(owner, bridge_callid);
      }

      ast_channel_unlock(owner);
   }

   /* We are done with the owner now that its call ID matches the bridge */
   ast_channel_unref(owner);
   owner = NULL;

   features = ast_bridge_features_new();
   if (!features) {
      ast_channel_unref(chan);
      return -1;
   }

   ast_set_flag(&features->feature_flags, flags);

   /* Impart the semi2 channel into the bridge */
   if (ast_bridge_impart(bridge, chan, NULL, features,
      AST_BRIDGE_IMPART_CHAN_INDEPENDENT)) {
      ast_channel_unref(chan);
      return -1;
   }

   /* The bridge thread now controls the chan ref from the ast_unreal_pvt */
   ao2_lock(p);
   ast_set_flag(p, AST_UNREAL_CARETAKER_THREAD);
   ao2_unlock(p);

   ast_channel_unref(chan);

   return 0;
}

int ast_unreal_hangup(struct ast_unreal_pvt *p, struct ast_channel *ast)
{
   int hangup_chan = 0;
   int res = 0;
   int cause;
   struct ast_channel *owner = NULL;
   struct ast_channel *chan = NULL;

   /* the pvt isn't going anywhere, it has a ref */
   ast_channel_unlock(ast);

   /* lock everything */
   ast_unreal_lock_all(p, &chan, &owner);

   if (ast != chan && ast != owner) {
      res = -1;
      goto unreal_hangup_cleanup;
   }

   cause = ast_channel_hangupcause(ast);

   ast_log(LOG_WARNING, "Unreal hangup\n");

   if (ast == p->chan) {
      /* Outgoing side is hanging up. */
      ast_clear_flag(p, AST_UNREAL_CARETAKER_THREAD);
      p->chan = NULL;
      if (p->owner) {
         const char *status = pbx_builtin_getvar_helper(p->chan, "DIALSTATUS");

         if (status) {
            ast_channel_hangupcause_set(p->owner, cause);
            pbx_builtin_setvar_helper(p->owner, "CHANLOCALSTATUS", status);
         }
         ast_queue_hangup_with_cause(p->owner, cause);
      }
   } else {
      /* Owner side is hanging up. */
      p->owner = NULL;
      if (p->chan) {
         if (cause == AST_CAUSE_ANSWERED_ELSEWHERE) {
            ast_channel_hangupcause_set(p->chan, AST_CAUSE_ANSWERED_ELSEWHERE);
            ast_debug(2, "%s has AST_CAUSE_ANSWERED_ELSEWHERE set.\n",
               ast_channel_name(p->chan));
         }
         if (!ast_test_flag(p, AST_UNREAL_CARETAKER_THREAD)) {
            /*
             * Need to actually hangup p->chan since nothing else is taking
             * care of it.
             */
            hangup_chan = 1;
         } else {
            ast_queue_hangup_with_cause(p->chan, cause);
         }
      }
   }

   /* this is one of our locked channels, doesn't matter which */
   ast_channel_tech_pvt_set(ast, NULL);
   ao2_ref(p, -1);

unreal_hangup_cleanup:
   ao2_unlock(p);
   if (owner) {
      ast_channel_unlock(owner);
      ast_channel_unref(owner);
   }
   if (chan) {
      ast_channel_unlock(chan);
      if (hangup_chan) {
         ast_hangup(chan);
      }
      ast_channel_unref(chan);
   }

   /* leave with the channel locked that came in */
   ast_channel_lock(ast);

   return res;
}

void ast_unreal_destructor(void *vdoomed)
{
   struct ast_unreal_pvt *doomed = vdoomed;

   ao2_cleanup(doomed->reqcap);
   doomed->reqcap = NULL;
   ast_stream_topology_free(doomed->reqtopology);
   doomed->reqtopology = NULL;
   ao2_cleanup(doomed->owner_old_topology);
   ao2_cleanup(doomed->chan_old_topology);
}

struct ast_unreal_pvt *ast_unreal_alloc(size_t size, ao2_destructor_fn destructor, struct ast_format_cap *cap)
{
   struct ast_stream_topology *topology;
   struct ast_unreal_pvt *unreal;

   topology = ast_stream_topology_create_from_format_cap(cap);
   if (!topology) {
      return NULL;
   }

   unreal = ast_unreal_alloc_stream_topology(size, destructor, topology);

   ast_stream_topology_free(topology);

   return unreal;
}

struct ast_unreal_pvt *ast_unreal_alloc_stream_topology(size_t size, ao2_destructor_fn destructor, struct ast_stream_topology *topology)
{
   struct ast_unreal_pvt *unreal;

   static const struct ast_jb_conf jb_conf = {
      .flags = 0,
      .max_size = -1,
      .resync_threshold = -1,
      .impl = "",
      .target_extra = -1,
   };

   unreal = ao2_alloc(size, destructor);
   if (!unreal) {
      return NULL;
   }

   unreal->reqtopology = ast_stream_topology_clone(topology);
   if (!unreal->reqtopology) {
      ao2_ref(unreal, -1);
      return NULL;
   }

   unreal->reqcap = ast_stream_topology_get_formats(topology);
   if (!unreal->reqcap) {
      ao2_ref(unreal, -1);
      return NULL;
   }

   memcpy(&unreal->jb_conf, &jb_conf, sizeof(unreal->jb_conf));

   return unreal;
}

struct ast_channel *ast_unreal_new_channels(struct ast_unreal_pvt *p,
   const struct ast_channel_tech *tech, int semi1_state, int semi2_state,
   const char *exten, const char *context, const struct ast_assigned_ids *assignedids,
   const struct ast_channel *requestor, ast_callid callid)
{
   struct ast_channel *owner;
   struct ast_channel *chan;
   RAII_VAR(struct ast_format *, fmt, NULL, ao2_cleanup);
   struct ast_assigned_ids id1 = {NULL, NULL};
   struct ast_assigned_ids id2 = {NULL, NULL};
   int generated_seqno = ast_atomic_fetchadd_int((int *) &name_sequence, +1);
   struct ast_stream_topology *topology;

   /* set unique ids for the two channels */
   if (assignedids && !ast_strlen_zero(assignedids->uniqueid)) {
      id1.uniqueid = assignedids->uniqueid;
      id2.uniqueid = assignedids->uniqueid2;
   }

   /* if id1 given but not id2, use default of id1;2 */
   if (id1.uniqueid && ast_strlen_zero(id2.uniqueid)) {
      char *uniqueid2;

      uniqueid2 = ast_alloca(strlen(id1.uniqueid) + 3);
      strcpy(uniqueid2, id1.uniqueid);/* Safe */
      strcat(uniqueid2, ";2");/* Safe */
      id2.uniqueid = uniqueid2;
   }

   /* We need to create a topology to place on the first channel, as we can't
    * share a single one between both.
    */
   topology = ast_stream_topology_clone(p->reqtopology);
   if (!topology) {
      return NULL;
   }

   /*
    * Allocate two new Asterisk channels
    *
    * Make sure that the ;2 channel gets the same linkedid as ;1.
    * You can't pass linkedid to both allocations since if linkedid
    * isn't set, then each channel will generate its own linkedid.
    */
   owner = ast_channel_alloc(1, semi1_state, NULL, NULL, NULL,
      exten, context, &id1, requestor, 0,
      "%s/%s-%08x;1", tech->type, p->name, (unsigned)generated_seqno);
   if (!owner) {
      ast_log(LOG_WARNING, "Unable to allocate owner channel structure\n");
      ast_stream_topology_free(topology);
      return NULL;
   }

   if (callid) {
      ast_channel_callid_set(owner, callid);
   }

   ast_channel_tech_set(owner, tech);
   ao2_ref(p, +1);
   ast_channel_tech_pvt_set(owner, p);

   ast_channel_nativeformats_set(owner, p->reqcap);

   if (ast_channel_is_multistream(owner)) {
      ast_channel_set_stream_topology(owner, topology);
   }

   /* Determine our read/write format and set it on each channel */
   fmt = ast_format_cap_get_format(p->reqcap, 0);
   if (!fmt) {
      ast_channel_tech_pvt_set(owner, NULL);
      ao2_ref(p, -1);
      ast_channel_unlock(owner);
      ast_channel_release(owner);
      return NULL;
   }

   ast_channel_set_writeformat(owner, fmt);
   ast_channel_set_rawwriteformat(owner, fmt);
   ast_channel_set_readformat(owner, fmt);
   ast_channel_set_rawreadformat(owner, fmt);

   ast_set_flag(ast_channel_flags(owner), AST_FLAG_DISABLE_DEVSTATE_CACHE);

   ast_jb_configure(owner, &p->jb_conf);

   if (ast_channel_cc_params_init(owner, requestor
      ? ast_channel_get_cc_config_params((struct ast_channel *) requestor) : NULL)) {
      ast_channel_tech_pvt_set(owner, NULL);
      ao2_ref(p, -1);
      ast_channel_tech_pvt_set(owner, NULL);
      ast_channel_unlock(owner);
      ast_channel_release(owner);
      return NULL;
   }

   p->owner = owner;
   ast_channel_unlock(owner);

   chan = ast_channel_alloc(1, semi2_state, NULL, NULL, NULL,
      exten, context, &id2, owner, 0,
      "%s/%s-%08x;2", tech->type, p->name, (unsigned)generated_seqno);
   if (!chan) {
      ast_log(LOG_WARNING, "Unable to allocate chan channel structure\n");
      ast_channel_tech_pvt_set(owner, NULL);
      ao2_ref(p, -1);
      ast_channel_tech_pvt_set(owner, NULL);
      ast_channel_release(owner);
      return NULL;
   }

   if (callid) {
      ast_channel_callid_set(chan, callid);
   }

   ast_channel_tech_set(chan, tech);
   ao2_ref(p, +1);
   ast_channel_tech_pvt_set(chan, p);

   ast_channel_nativeformats_set(chan, p->reqcap);

   if (ast_channel_is_multistream(chan)) {
      ast_channel_set_stream_topology(chan, p->reqtopology);
      p->reqtopology = NULL;
   }

   /* Format was already determined when setting up owner */
   ast_channel_set_writeformat(chan, fmt);
   ast_channel_set_rawwriteformat(chan, fmt);
   ast_channel_set_readformat(chan, fmt);
   ast_channel_set_rawreadformat(chan, fmt);

   ast_set_flag(ast_channel_flags(chan), AST_FLAG_DISABLE_DEVSTATE_CACHE);

   p->chan = chan;
   ast_channel_unlock(chan);

   return owner;
}