app_confbridge.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2007-2008, Digium, Inc.
 *
 * Joshua Colp <jcolp@digium.com>
 *
 * 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 Conference Bridge application
 *
 * \author\verbatim Joshua Colp <jcolp@digium.com> \endverbatim
 *
 * This is a conference bridge application utilizing the bridging core.
 * \ingroup applications
 */

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 324306 $")

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>

#include "asterisk/file.h"
#include "asterisk/logger.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/module.h"
#include "asterisk/lock.h"
#include "asterisk/app.h"
#include "asterisk/bridging.h"
#include "asterisk/musiconhold.h"
#include "asterisk/say.h"
#include "asterisk/audiohook.h"
#include "asterisk/astobj2.h"

/*** DOCUMENTATION
        <application name="ConfBridge" language="en_US">
                <synopsis>
                        Conference bridge application.
                </synopsis>
                <syntax>
                        <parameter name="confno">
                                <para>The conference number</para>
                        </parameter>
                        <parameter name="options">
                                <optionlist>
                                        <option name="a">
                                                <para>Set admin mode.</para>
                                        </option>
                                        <option name="A">
                                                <para>Set marked mode.</para>
                                        </option>
                                        <option name="c">
                                                <para>Announce user(s) count on joining a conference.</para>
                                        </option>
                                        <option name="m">
                                                <para>Set initially muted.</para>
                                        </option>
                                        <option name="M" hasparams="optional">
                                                <para>Enable music on hold when the conference has a single caller. Optionally,
                                                specify a musiconhold class to use. If one is not provided, it will use the
                                                channel's currently set music class, or <literal>default</literal>.</para>
                                                <argument name="class" required="true" />
                                        </option>
                                        <option name="1">
                                                <para>Do not play message when first person enters</para>
                                        </option>
                                        <option name="s">
                                                <para>Present menu (user or admin) when <literal>*</literal> is received
                                                (send to menu).</para>
                                        </option>
                                        <option name="w">
                                                <para>Wait until the marked user enters the conference.</para>
                                        </option>
                                        <option name="q">
                                                <para>Quiet mode (don't play enter/leave sounds).</para>
                                        </option>
            </optionlist>
            </parameter>
                </syntax>
                <description>
                        <para>Enters the user into a specified conference bridge. The user can exit the conference by hangup only.</para>
                        <para>The join sound can be set using the <literal>CONFBRIDGE_JOIN_SOUND</literal> variable and the leave sound can be set using the <literal>CONFBRIDGE_LEAVE_SOUND</literal> variable. These can be unique to the caller.</para>
         <note><para>This application will not automatically answer the channel.</para></note>
                </description>
        </application>
***/

/*!
 * \par Playing back a file to a channel in a conference
 * You might notice in this application that while playing a sound file
 * to a channel the actual conference bridge lock is not held. This is done so
 * that other channels are not blocked from interacting with the conference bridge.
 * Unfortunately because of this it is possible for things to change after the sound file
 * is done being played. Data must therefore be checked after reacquiring the conference
 * bridge lock if it is important.
 */

static const char *app = "ConfBridge";

enum {
   OPTION_ADMIN = (1 << 0),             /*!< Set if the caller is an administrator */
   OPTION_MENU = (1 << 1),              /*!< Set if the caller should have access to the conference bridge IVR menu */
   OPTION_MUSICONHOLD = (1 << 2),       /*!< Set if music on hold should be played if nobody else is in the conference bridge */
   OPTION_NOONLYPERSON = (1 << 3),      /*!< Set if the "you are currently the only person in this conference" sound file should not be played */
   OPTION_STARTMUTED = (1 << 4),        /*!< Set if the caller should be initially set muted */
   OPTION_ANNOUNCEUSERCOUNT = (1 << 5), /*!< Set if the number of users should be announced to the caller */
   OPTION_MARKEDUSER = (1 << 6),        /*!< Set if the caller is a marked user */
   OPTION_WAITMARKED = (1 << 7),        /*!< Set if the conference must wait for a marked user before starting */
   OPTION_QUIET = (1 << 8),             /*!< Set if no audio prompts should be played */
};

enum {
   OPTION_MUSICONHOLD_CLASS,            /*!< If the 'M' option is set, the music on hold class to play */
   /*This must be the last element */
   OPTION_ARRAY_SIZE,
};

AST_APP_OPTIONS(app_opts,{
   AST_APP_OPTION('A', OPTION_MARKEDUSER),
   AST_APP_OPTION('a', OPTION_ADMIN),
   AST_APP_OPTION('c', OPTION_ANNOUNCEUSERCOUNT),
   AST_APP_OPTION('m', OPTION_STARTMUTED),
   AST_APP_OPTION_ARG('M', OPTION_MUSICONHOLD, OPTION_MUSICONHOLD_CLASS),
   AST_APP_OPTION('1', OPTION_NOONLYPERSON),
   AST_APP_OPTION('s', OPTION_MENU),
   AST_APP_OPTION('w', OPTION_WAITMARKED),
   AST_APP_OPTION('q', OPTION_QUIET),
});

/* Maximum length of a conference bridge name */
#define MAX_CONF_NAME 32

/* Number of buckets our conference bridges container can have */
#define CONFERENCE_BRIDGE_BUCKETS 53

/*! \brief The structure that represents a conference bridge */
struct conference_bridge {
   char name[MAX_CONF_NAME];                                         /*!< Name of the conference bridge */
   struct ast_bridge *bridge;                                        /*!< Bridge structure doing the mixing */
   unsigned int users;                                               /*!< Number of users present */
   unsigned int markedusers;                                         /*!< Number of marked users present */
   unsigned int locked:1;                                            /*!< Is this conference bridge locked? */
   AST_LIST_HEAD_NOLOCK(, conference_bridge_user) users_list;        /*!< List of users participating in the conference bridge */
   struct ast_channel *playback_chan;                                /*!< Channel used for playback into the conference bridge */
   ast_mutex_t playback_lock;                                        /*!< Lock used for playback channel */
};

/*! \brief The structure that represents a conference bridge user */
struct conference_bridge_user {
   struct conference_bridge *conference_bridge; /*!< Conference bridge they are participating in */
   struct ast_channel *chan;                    /*!< Asterisk channel participating */
   struct ast_flags flags;                      /*!< Flags passed in when the application was called */
   char *opt_args[OPTION_ARRAY_SIZE];           /*!< Arguments to options passed when application was called */
   struct ast_bridge_features features;         /*!< Bridge features structure */
   unsigned int kicked:1;                       /*!< User has been kicked from the conference */
   AST_LIST_ENTRY(conference_bridge_user) list; /*!< Linked list information */
};

/*! \brief Container to hold all conference bridges in progress */
static struct ao2_container *conference_bridges;

static int play_sound_file(struct conference_bridge *conference_bridge, const char *filename);

/*! \brief Hashing function used for conference bridges container */
static int conference_bridge_hash_cb(const void *obj, const int flags)
{
   const struct conference_bridge *conference_bridge = obj;
   return ast_str_case_hash(conference_bridge->name);
}

/*! \brief Comparison function used for conference bridges container */
static int conference_bridge_cmp_cb(void *obj, void *arg, int flags)
{
   const struct conference_bridge *conference_bridge0 = obj, *conference_bridge1 = arg;
   return (!strcasecmp(conference_bridge0->name, conference_bridge1->name) ? CMP_MATCH | CMP_STOP : 0);
}

/*!
 * \brief Announce number of users in the conference bridge to the caller
 *
 * \param conference_bridge Conference bridge to peek at
 * \param conference_bridge_user Caller
 *
 * \return Returns 0 on success, -1 if the user hung up
 */
static int announce_user_count(struct conference_bridge *conference_bridge, struct conference_bridge_user *conference_bridge_user)
{
   if (conference_bridge->users == 1) {
      /* Awww we are the only person in the conference bridge */
      return 0;
   } else if (conference_bridge->users == 2) {
      /* Eep, there is one other person */
      if (ast_stream_and_wait(conference_bridge_user->chan, "conf-onlyone", "")) {
         return -1;
      }
   } else {
      /* Alas multiple others in here */
      if (ast_stream_and_wait(conference_bridge_user->chan, "conf-thereare", "")) {
         return -1;
      }
      if (ast_say_number(conference_bridge_user->chan, conference_bridge->users - 1, "", conference_bridge_user->chan->language, NULL)) {
         return -1;
      }
      if (ast_stream_and_wait(conference_bridge_user->chan, "conf-otherinparty", "")) {
         return -1;
      }
   }
   return 0;
}

/*!
 * \brief Play back an audio file to a channel
 *
 * \param conference_bridge Conference bridge they are in
 * \param chan Channel to play audio prompt to
 * \param file Prompt to play
 *
 * \return Returns 0 on success, -1 if the user hung up
 *
 * \note This function assumes that conference_bridge is locked
 */
static int play_prompt_to_channel(struct conference_bridge *conference_bridge, struct ast_channel *chan, const char *file)
{
   int res;
   ao2_unlock(conference_bridge);
   res = ast_stream_and_wait(chan, file, "");
   ao2_lock(conference_bridge);
   return res;
}

/*!
 * \brief Perform post-joining marked specific actions
 *
 * \param conference_bridge Conference bridge being joined
 * \param conference_bridge_user Conference bridge user joining
 *
 * \return Returns 0 on success, -1 if the user hung up
 */
static int post_join_marked(struct conference_bridge *conference_bridge, struct conference_bridge_user *conference_bridge_user)
{
   if (ast_test_flag(&conference_bridge_user->flags, OPTION_MARKEDUSER)) {
      struct conference_bridge_user *other_conference_bridge_user = NULL;

      /* If we are not the first marked user to join just bail out now */
      if (conference_bridge->markedusers >= 2) {
         return 0;
      }

      /* Iterate through every participant stopping MOH on them if need be */
      AST_LIST_TRAVERSE(&conference_bridge->users_list, other_conference_bridge_user, list) {
         if (other_conference_bridge_user == conference_bridge_user) {
            continue;
         }
         if (ast_test_flag(&other_conference_bridge_user->flags, OPTION_MUSICONHOLD) && !ast_bridge_suspend(conference_bridge->bridge, other_conference_bridge_user->chan)) {
            ast_moh_stop(other_conference_bridge_user->chan);
            ast_bridge_unsuspend(conference_bridge->bridge, other_conference_bridge_user->chan);
         }
      }

      /* Next play the audio file stating they are going to be placed into the conference */
      if (!ast_test_flag(&conference_bridge_user->flags, OPTION_QUIET)) {
         ao2_unlock(conference_bridge);
         ast_autoservice_start(conference_bridge_user->chan);
         play_sound_file(conference_bridge, "conf-placeintoconf");
         ast_autoservice_stop(conference_bridge_user->chan);
         ao2_lock(conference_bridge);
      }

      /* Finally iterate through and unmute them all */
      AST_LIST_TRAVERSE(&conference_bridge->users_list, other_conference_bridge_user, list) {
         if (other_conference_bridge_user == conference_bridge_user) {
            continue;
         }
         other_conference_bridge_user->features.mute = 0;
      }

   } else {
      /* If a marked user already exists in the conference bridge we can just bail out now */
      if (conference_bridge->markedusers) {
         return 0;
      }
      /* Be sure we are muted so we can't talk to anybody else waiting */
      conference_bridge_user->features.mute = 1;
      /* If we have not been quieted play back that they are waiting for the leader */
      if (!ast_test_flag(&conference_bridge_user->flags, OPTION_QUIET)) {
         if (play_prompt_to_channel(conference_bridge, conference_bridge_user->chan, "conf-waitforleader")) {
            /* user hung up while the sound was playing */
            return -1;
         }
      }
      /* Start music on hold if needed */
      /* We need to recheck the markedusers value here. play_prompt_to_channel unlocks the conference bridge, potentially
       * allowing a marked user to enter while the prompt was playing
       */
      if (!conference_bridge->markedusers && ast_test_flag(&conference_bridge_user->flags, OPTION_MUSICONHOLD)) {
         ast_moh_start(conference_bridge_user->chan, conference_bridge_user->opt_args[OPTION_MUSICONHOLD_CLASS], NULL);
      }
   }
   return 0;
}

/*!
 * \brief Perform post-joining non-marked specific actions
 *
 * \param conference_bridge Conference bridge being joined
 * \param conference_bridge_user Conference bridge user joining
 *
 * \return Returns 0 on success, -1 if the user hung up
 */
static int post_join_unmarked(struct conference_bridge *conference_bridge, struct conference_bridge_user *conference_bridge_user)
{
   /* Play back audio prompt and start MOH if need be if we are the first participant */
   if (conference_bridge->users == 1) {
      /* If audio prompts have not been quieted or this prompt quieted play it on out */
      if (!ast_test_flag(&conference_bridge_user->flags, OPTION_QUIET | OPTION_NOONLYPERSON)) {
         if (play_prompt_to_channel(conference_bridge, conference_bridge_user->chan, "conf-onlyperson")) {
            /* user hung up while the sound was playing */
            return -1;
         }
      }
      /* If we need to start music on hold on the channel do so now */
      /* We need to re-check the number of users in the conference bridge here because another conference bridge
       * participant could have joined while the above prompt was playing for the first user.
       */
      if (conference_bridge->users == 1 && ast_test_flag(&conference_bridge_user->flags, OPTION_MUSICONHOLD)) {
         ast_moh_start(conference_bridge_user->chan, conference_bridge_user->opt_args[OPTION_MUSICONHOLD_CLASS], NULL);
      }
      return 0;
   }

   /* Announce number of users if need be */
   if (ast_test_flag(&conference_bridge_user->flags, OPTION_ANNOUNCEUSERCOUNT)) {
      ao2_unlock(conference_bridge);
      if (announce_user_count(conference_bridge, conference_bridge_user)) {
         ao2_lock(conference_bridge);
         return -1;
      }
      ao2_lock(conference_bridge);
   }

   /* If we are the second participant we may need to stop music on hold on the first */
   if (conference_bridge->users == 2) {
      struct conference_bridge_user *first_participant = AST_LIST_FIRST(&conference_bridge->users_list);

      /* Temporarily suspend the above participant from the bridge so we have control to stop MOH if needed */
      if (ast_test_flag(&first_participant->flags, OPTION_MUSICONHOLD) && !ast_bridge_suspend(conference_bridge->bridge, first_participant->chan)) {
         ast_moh_stop(first_participant->chan);
         ast_bridge_unsuspend(conference_bridge->bridge, first_participant->chan);
      }
   }
   return 0;
}

/*!
 * \brief Destroy a conference bridge
 *
 * \param obj The conference bridge object
 *
 * \return Returns nothing
 */
static void destroy_conference_bridge(void *obj)
{
   struct conference_bridge *conference_bridge = obj;

   ast_debug(1, "Destroying conference bridge '%s'\n", conference_bridge->name);

   ast_mutex_destroy(&conference_bridge->playback_lock);

   if (conference_bridge->playback_chan) {
      struct ast_channel *underlying_channel = conference_bridge->playback_chan->tech->bridged_channel(conference_bridge->playback_chan, NULL);
      ast_hangup(underlying_channel);
      ast_hangup(conference_bridge->playback_chan);
      conference_bridge->playback_chan = NULL;
   }

   /* Destroying a conference bridge is simple, all we have to do is destroy the bridging object */
   if (conference_bridge->bridge) {
      ast_bridge_destroy(conference_bridge->bridge);
      conference_bridge->bridge = NULL;
   }
}

static void leave_conference_bridge(struct conference_bridge *conference_bridge, struct conference_bridge_user *conference_bridge_user);

/*!
 * \brief Join a conference bridge
 *
 * \param name The conference name
 * \param conference_bridge_user Conference bridge user structure
 *
 * \return A pointer to the conference bridge struct, or NULL if the conference room wasn't found.
 */
static struct conference_bridge *join_conference_bridge(const char *name, struct conference_bridge_user *conference_bridge_user)
{
   struct conference_bridge *conference_bridge = NULL;
   struct conference_bridge tmp;

   ast_copy_string(tmp.name, name, sizeof(tmp.name));

   /* We explictly lock the conference bridges container ourselves so that other callers can not create duplicate conferences at the same */
   ao2_lock(conference_bridges);

   ast_debug(1, "Trying to find conference bridge '%s'\n", name);

   /* Attempt to find an existing conference bridge */
   conference_bridge = ao2_find(conference_bridges, &tmp, OBJ_POINTER);

   /* When finding a conference bridge that already exists make sure that it is not locked, and if so that we are not an admin */
   if (conference_bridge && conference_bridge->locked && !ast_test_flag(&conference_bridge_user->flags, OPTION_ADMIN)) {
      ao2_unlock(conference_bridges);
      ao2_ref(conference_bridge, -1);
      ast_debug(1, "Conference bridge '%s' is locked and caller is not an admin\n", name);
      ast_stream_and_wait(conference_bridge_user->chan, "conf-locked", "");
      return NULL;
   }

   /* If no conference bridge was found see if we can create one */
   if (!conference_bridge) {
      /* Try to allocate memory for a new conference bridge, if we fail... this won't end well. */
      if (!(conference_bridge = ao2_alloc(sizeof(*conference_bridge), destroy_conference_bridge))) {
         ao2_unlock(conference_bridges);
         ast_log(LOG_ERROR, "Conference bridge '%s' does not exist.\n", name);
         return NULL;
      }

      /* Setup conference bridge parameters */
      ast_copy_string(conference_bridge->name, name, sizeof(conference_bridge->name));

      /* Create an actual bridge that will do the audio mixing */
      if (!(conference_bridge->bridge = ast_bridge_new(AST_BRIDGE_CAPABILITY_1TO1MIX, AST_BRIDGE_FLAG_SMART))) {
         ao2_ref(conference_bridge, -1);
         conference_bridge = NULL;
         ao2_unlock(conference_bridges);
         ast_log(LOG_ERROR, "Conference bridge '%s' could not be created.\n", name);
         return NULL;
      }

      /* Setup lock for playback channel */
      ast_mutex_init(&conference_bridge->playback_lock);

      /* Link it into the conference bridges container */
      ao2_link(conference_bridges, conference_bridge);

      ast_debug(1, "Created conference bridge '%s' and linked to container '%p'\n", name, conference_bridges);
   }

   ao2_unlock(conference_bridges);

   /* Setup conference bridge user parameters */
   conference_bridge_user->conference_bridge = conference_bridge;

   ao2_lock(conference_bridge);

   /* All good to go, add them in */
   AST_LIST_INSERT_TAIL(&conference_bridge->users_list, conference_bridge_user, list);

   /* Increment the users count on the bridge, but record it as it is going to need to be known right after this */
   conference_bridge->users++;

   /* If the caller is a marked user bump up the count */
   if (ast_test_flag(&conference_bridge_user->flags, OPTION_MARKEDUSER)) {
      conference_bridge->markedusers++;
   }

   /* If the caller is a marked user or is waiting for a marked user to enter pass 'em off, otherwise pass them off to do regular joining stuff */
   if (ast_test_flag(&conference_bridge_user->flags, OPTION_MARKEDUSER | OPTION_WAITMARKED)) {
      if (post_join_marked(conference_bridge, conference_bridge_user)) {
         ao2_unlock(conference_bridge);
         leave_conference_bridge(conference_bridge, conference_bridge_user);
         return NULL;
      }
   } else {
      if (post_join_unmarked(conference_bridge, conference_bridge_user)) {
         ao2_unlock(conference_bridge);
         leave_conference_bridge(conference_bridge, conference_bridge_user);
         return NULL;
      }
   }

   ao2_unlock(conference_bridge);

   return conference_bridge;
}

/*!
 * \brief Leave a conference bridge
 *
 * \param conference_bridge The conference bridge to leave
 * \param conference_bridge_user The conference bridge user structure
 *
 */
static void  leave_conference_bridge(struct conference_bridge *conference_bridge, struct conference_bridge_user *conference_bridge_user)
{
   ao2_lock(conference_bridge);

   /* If this caller is a marked user bump down the count */
   if (ast_test_flag(&conference_bridge_user->flags, OPTION_MARKEDUSER)) {
      conference_bridge->markedusers--;
   }

   /* Decrement the users count while keeping the previous participant count */
   conference_bridge->users--;

   /* Drop conference bridge user from the list, they be going bye bye */
   AST_LIST_REMOVE(&conference_bridge->users_list, conference_bridge_user, list);

   /* If there are still users in the conference bridge we may need to do things (such as start MOH on them) */
   if (conference_bridge->users) {
      if (ast_test_flag(&conference_bridge_user->flags, OPTION_MARKEDUSER) && !conference_bridge->markedusers) {
         struct conference_bridge_user *other_participant = NULL;

         /* Start out with muting everyone */
         AST_LIST_TRAVERSE(&conference_bridge->users_list, other_participant, list) {
            other_participant->features.mute = 1;
         }

         /* Play back the audio prompt saying the leader has left the conference */
         if (!ast_test_flag(&conference_bridge_user->flags, OPTION_QUIET)) {
            ao2_unlock(conference_bridge);
            ast_autoservice_start(conference_bridge_user->chan);
            play_sound_file(conference_bridge, "conf-leaderhasleft");
            ast_autoservice_stop(conference_bridge_user->chan);
            ao2_lock(conference_bridge);
         }

         /* Now on to starting MOH if needed */
         AST_LIST_TRAVERSE(&conference_bridge->users_list, other_participant, list) {
            if (ast_test_flag(&other_participant->flags, OPTION_MUSICONHOLD) && !ast_bridge_suspend(conference_bridge->bridge, other_participant->chan)) {
               ast_moh_start(other_participant->chan, other_participant->opt_args[OPTION_MUSICONHOLD_CLASS], NULL);
               ast_bridge_unsuspend(conference_bridge->bridge, other_participant->chan);
            }
         }
      } else if (conference_bridge->users == 1) {
         /* Of course if there is one other person in here we may need to start up MOH on them */
         struct conference_bridge_user *first_participant = AST_LIST_FIRST(&conference_bridge->users_list);

         if (ast_test_flag(&first_participant->flags, OPTION_MUSICONHOLD) && !ast_bridge_suspend(conference_bridge->bridge, first_participant->chan)) {
            ast_moh_start(first_participant->chan, first_participant->opt_args[OPTION_MUSICONHOLD_CLASS], NULL);
            ast_bridge_unsuspend(conference_bridge->bridge, first_participant->chan);
         }
      }
   } else {
      ao2_unlink(conference_bridges, conference_bridge);
   }

   /* Done mucking with the conference bridge, huzzah */
   ao2_unlock(conference_bridge);

   ao2_ref(conference_bridge, -1);
}

/*!
 * \brief Play sound file into conference bridge
 *
 * \param conference_bridge The conference bridge to play sound file into
 * \param filename Sound file to play
 *
 * \retval 0 success
 * \retval -1 failure
 */
static int play_sound_file(struct conference_bridge *conference_bridge, const char *filename)
{
   struct ast_channel *underlying_channel;

   ast_mutex_lock(&conference_bridge->playback_lock);

   if (!(conference_bridge->playback_chan)) {
      int cause;

      if (!(conference_bridge->playback_chan = ast_request("Bridge", AST_FORMAT_SLINEAR, "", &cause))) {
         ast_mutex_unlock(&conference_bridge->playback_lock);
         return -1;
      }

      conference_bridge->playback_chan->bridge = conference_bridge->bridge;

      if (ast_call(conference_bridge->playback_chan, "", 0)) {
         ast_hangup(conference_bridge->playback_chan);
         conference_bridge->playback_chan = NULL;
         ast_mutex_unlock(&conference_bridge->playback_lock);
         return -1;
      }

      ast_debug(1, "Created a playback channel to conference bridge '%s'\n", conference_bridge->name);

      underlying_channel = conference_bridge->playback_chan->tech->bridged_channel(conference_bridge->playback_chan, NULL);
   } else {
      /* Channel was already available so we just need to add it back into the bridge */
      underlying_channel = conference_bridge->playback_chan->tech->bridged_channel(conference_bridge->playback_chan, NULL);
      ast_bridge_impart(conference_bridge->bridge, underlying_channel, NULL, NULL);
   }

   /* The channel is all under our control, in goes the prompt */
   ast_stream_and_wait(conference_bridge->playback_chan, filename, "");

   ast_debug(1, "Departing underlying channel '%s' from bridge '%p'\n", underlying_channel->name, conference_bridge->bridge);
   ast_bridge_depart(conference_bridge->bridge, underlying_channel);

   ast_mutex_unlock(&conference_bridge->playback_lock);

   return 0;
}

/*!
 * \brief DTMF Menu Callback
 *
 * \param bridge Bridge this is involving
 * \param bridge_channel Bridged channel this is involving
 * \param hook_pvt User's conference bridge structure
 *
 * \retval 0 success
 * \retval -1 failure
 */
static int menu_callback(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, void *hook_pvt)
{
   struct conference_bridge_user *conference_bridge_user = hook_pvt;
   struct conference_bridge *conference_bridge = conference_bridge_user->conference_bridge;
   int digit, res = 0, isadmin = ast_test_flag(&conference_bridge_user->flags, OPTION_ADMIN);

   /* See if music on hold is playing */
   ao2_lock(conference_bridge);
   if (conference_bridge->users == 1 && ast_test_flag(&conference_bridge_user->flags, OPTION_MUSICONHOLD)) {
      /* Just us so MOH is probably indeed going, let's stop it */
      ast_moh_stop(bridge_channel->chan);
   }
   ao2_unlock(conference_bridge);

   /* Try to play back the user menu, if it fails pass this back up so the bridging core will act on it */
   if (ast_streamfile(bridge_channel->chan, (isadmin ? "conf-adminmenu" : "conf-usermenu"), bridge_channel->chan->language)) {
      res = -1;
      goto finished;
   }

   /* Wait for them to enter a digit from the user menu options */
   digit = ast_waitstream(bridge_channel->chan, AST_DIGIT_ANY);
   ast_stopstream(bridge_channel->chan);

   if (digit == '1') {
      /* 1 - Mute or unmute yourself, note we only allow manipulation if they aren't waiting for a marked user or if marked users exist */
      if (!ast_test_flag(&conference_bridge_user->flags, OPTION_WAITMARKED) || conference_bridge->markedusers) {
         conference_bridge_user->features.mute = (!conference_bridge_user->features.mute ? 1 : 0);
      }
      res = ast_stream_and_wait(bridge_channel->chan, (conference_bridge_user->features.mute ? "conf-muted" : "conf-unmuted"), "");
   } else if (isadmin && digit == '2') {
      /* 2 - Unlock or lock conference */
      conference_bridge->locked = (!conference_bridge->locked ? 1 : 0);
      res = ast_stream_and_wait(bridge_channel->chan, (conference_bridge->locked ? "conf-lockednow" : "conf-unlockednow"), "");
   } else if (isadmin && digit == '3') {
      /* 3 - Eject last user */
      struct conference_bridge_user *last_participant = NULL;

      ao2_lock(conference_bridge);
      if (((last_participant = AST_LIST_LAST(&conference_bridge->users_list)) == conference_bridge_user) || (ast_test_flag(&last_participant->flags, OPTION_ADMIN))) {
         ao2_unlock(conference_bridge);
         res = ast_stream_and_wait(bridge_channel->chan, "conf-errormenu", "");
      } else {
         last_participant->kicked = 1;
         ast_bridge_remove(conference_bridge->bridge, last_participant->chan);
         ao2_unlock(conference_bridge);
      }
   } else if (digit == '4') {
      /* 4 - Decrease listening volume */
      ast_audiohook_volume_adjust(conference_bridge_user->chan, AST_AUDIOHOOK_DIRECTION_WRITE, -1);
   } else if (digit == '6') {
      /* 6 - Increase listening volume */
      ast_audiohook_volume_adjust(conference_bridge_user->chan, AST_AUDIOHOOK_DIRECTION_WRITE, 1);
   } else if (digit == '7') {
      /* 7 - Decrease talking volume */
      ast_audiohook_volume_adjust(conference_bridge_user->chan, AST_AUDIOHOOK_DIRECTION_READ, -1);
   } else if (digit == '8') {
      /* 8 - Exit the IVR */
   } else if (digit == '9') {
      /* 9 - Increase talking volume */
      ast_audiohook_volume_adjust(conference_bridge_user->chan, AST_AUDIOHOOK_DIRECTION_READ, 1);
   } else {
      /* No valid option was selected */
      res = ast_stream_and_wait(bridge_channel->chan, "conf-errormenu", "");
   }

 finished:
   /* See if music on hold needs to be started back up again */
   ao2_lock(conference_bridge);
   if (conference_bridge->users == 1 && ast_test_flag(&conference_bridge_user->flags, OPTION_MUSICONHOLD)) {
      ast_moh_start(bridge_channel->chan, conference_bridge_user->opt_args[OPTION_MUSICONHOLD_CLASS], NULL);
   }
   ao2_unlock(conference_bridge);

   bridge_channel->state = AST_BRIDGE_CHANNEL_STATE_WAIT;

   return res;
}

/*! \brief The ConfBridge application */
static int confbridge_exec(struct ast_channel *chan, void *data)
{
   int res = 0, volume_adjustments[2];
   char *parse;
   struct conference_bridge *conference_bridge = NULL;
   struct conference_bridge_user conference_bridge_user = {
      .chan = chan,
   };
   const char *tmp, *join_sound = NULL, *leave_sound = NULL;
   AST_DECLARE_APP_ARGS(args,
      AST_APP_ARG(conf_name);
      AST_APP_ARG(options);
   );

   if (ast_strlen_zero(data)) {
      ast_log(LOG_WARNING, "%s requires an argument (conference name[,options])\n", app);
      return -1;
   }

   /* We need to make a copy of the input string if we are going to modify it! */
   parse = ast_strdupa(data);

   AST_STANDARD_APP_ARGS(args, parse);

   if (args.argc == 2) {
      ast_app_parse_options(app_opts, &conference_bridge_user.flags, conference_bridge_user.opt_args, args.options);
   }

   /* Look for a conference bridge matching the provided name */
   if (!(conference_bridge = join_conference_bridge(args.conf_name, &conference_bridge_user))) {
      return -1;
   }

   /* Keep a copy of volume adjustments so we can restore them later if need be */
   volume_adjustments[0] = ast_audiohook_volume_get(chan, AST_AUDIOHOOK_DIRECTION_READ);
   volume_adjustments[1] = ast_audiohook_volume_get(chan, AST_AUDIOHOOK_DIRECTION_WRITE);

   /* Always initialize the features structure, we are in most cases always going to need it. */
   ast_bridge_features_init(&conference_bridge_user.features);

   /* If the menu option is enabled provide a user or admin menu as a custom feature hook */
   if (ast_test_flag(&conference_bridge_user.flags, OPTION_MENU)) {
      ast_bridge_features_hook(&conference_bridge_user.features, "#", menu_callback, &conference_bridge_user);
   }

   /* If the caller should be joined already muted, make it so */
   if (ast_test_flag(&conference_bridge_user.flags, OPTION_STARTMUTED)) {
      conference_bridge_user.features.mute = 1;
   }

   /* Grab join/leave sounds from the channel */
   ast_channel_lock(chan);
   if ((tmp = pbx_builtin_getvar_helper(chan, "CONFBRIDGE_JOIN_SOUND"))) {
      join_sound = ast_strdupa(tmp);
   }
   if ((tmp = pbx_builtin_getvar_helper(chan, "CONFBRIDGE_LEAVE_SOUND"))) {
      leave_sound = ast_strdupa(tmp);
   }
   ast_channel_unlock(chan);

   /* If there is 1 or more people already in the conference then play our join sound unless overridden */
   if (!ast_test_flag(&conference_bridge_user.flags, OPTION_QUIET) && !ast_strlen_zero(join_sound) && conference_bridge->users >= 2) {
      ast_autoservice_start(chan);
      play_sound_file(conference_bridge, join_sound);
      ast_autoservice_stop(chan);
   }

   /* Join our conference bridge for real */
   ast_bridge_join(conference_bridge->bridge, chan, NULL, &conference_bridge_user.features);

   /* If there is 1 or more people (not including us) already in the conference then play our leave sound unless overridden */
   if (!ast_test_flag(&conference_bridge_user.flags, OPTION_QUIET) && !ast_strlen_zero(leave_sound) && conference_bridge->users >= 2) {
      ast_autoservice_start(chan);
      play_sound_file(conference_bridge, leave_sound);
      ast_autoservice_stop(chan);
   }

   /* Easy as pie, depart this channel from the conference bridge */
   leave_conference_bridge(conference_bridge, &conference_bridge_user);
   conference_bridge = NULL;

   /* Can't forget to clean up the features structure, or else we risk a memory leak */
   ast_bridge_features_cleanup(&conference_bridge_user.features);

   /* If the user was kicked from the conference play back the audio prompt for it */
   if (!ast_test_flag(&conference_bridge_user.flags, OPTION_QUIET) && conference_bridge_user.kicked) {
      res = ast_stream_and_wait(chan, "conf-kicked", "");
   }

   /* Restore volume adjustments to previous values in case they were changed */
   if (volume_adjustments[0]) {
      ast_audiohook_volume_set(chan, AST_AUDIOHOOK_DIRECTION_READ, volume_adjustments[0]);
   }
   if (volume_adjustments[1]) {
      ast_audiohook_volume_set(chan, AST_AUDIOHOOK_DIRECTION_WRITE, volume_adjustments[1]);
   }

   return res;
}

/*! \brief Called when module is being unloaded */
static int unload_module(void)
{
   int res = ast_unregister_application(app);

   /* Get rid of the conference bridges container. Since we only allow dynamic ones none will be active. */
   ao2_ref(conference_bridges, -1);

   return res;
}

/*! \brief Called when module is being loaded */
static int load_module(void)
{
   /* Create a container to hold the conference bridges */
   if (!(conference_bridges = ao2_container_alloc(CONFERENCE_BRIDGE_BUCKETS, conference_bridge_hash_cb, conference_bridge_cmp_cb))) {
      return AST_MODULE_LOAD_DECLINE;
   }

   if (ast_register_application_xml(app, confbridge_exec)) {
      ao2_ref(conference_bridges, -1);
      return AST_MODULE_LOAD_DECLINE;
   }

   return AST_MODULE_LOAD_SUCCESS;
}

AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Conference Bridge Application");