channel.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2006, Digium, Inc.
 *
 * Mark Spencer <markster@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 Channel Management
 *
 * \author Mark Spencer <markster@digium.com>
 */

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

#include "asterisk.h"

#include "asterisk/_private.h"

#include <sys/time.h>
#include <signal.h>
#include <math.h>

#include "asterisk/paths.h"   /* use ast_config_AST_SYSTEM_NAME */

#include "asterisk/pbx.h"
#include "asterisk/frame.h"
#include "asterisk/mod_format.h"
#include "asterisk/sched.h"
#include "asterisk/channel.h"
#include "asterisk/musiconhold.h"
#include "asterisk/say.h"
#include "asterisk/file.h"
#include "asterisk/cli.h"
#include "asterisk/translate.h"
#include "asterisk/manager.h"
#include "asterisk/chanvars.h"
#include "asterisk/linkedlists.h"
#include "asterisk/indications.h"
#include "asterisk/causes.h"
#include "asterisk/callerid.h"
#include "asterisk/utils.h"
#include "asterisk/lock.h"
#include "asterisk/app.h"
#include "asterisk/transcap.h"
#include "asterisk/devicestate.h"
#include "asterisk/threadstorage.h"
#include "asterisk/slinfactory.h"
#include "asterisk/audiohook.h"
#include "asterisk/framehook.h"
#include "asterisk/timing.h"
#include "asterisk/autochan.h"
#include "asterisk/stringfields.h"
#include "asterisk/global_datastores.h"
#include "asterisk/channel_internal.h"
#include "asterisk/features.h"
#include "asterisk/bridge.h"
#include "asterisk/test.h"
#include "asterisk/stasis_channels.h"
#include "asterisk/max_forwards.h"
#include "asterisk/stream.h"
#include "asterisk/message.h"

/*** DOCUMENTATION
 ***/

#if defined(KEEP_TILL_CHANNEL_PARTY_NUMBER_INFO_NEEDED)
#if defined(HAVE_PRI)
#include "libpri.h"
#endif   /* defined(HAVE_PRI) */
#endif   /* defined(KEEP_TILL_CHANNEL_PARTY_NUMBER_INFO_NEEDED) */

/* uncomment if you have problems with 'monitoring' synchronized files */
#if 0
#define MONITOR_CONSTANT_DELAY
#define MONITOR_DELAY   150 * 8     /*!< 150 ms of MONITORING DELAY */
#endif

static int chancount;

unsigned long global_fin, global_fout;

AST_THREADSTORAGE(state2str_threadbuf);
#define STATE2STR_BUFSIZE   32

/*! Default amount of time to use when emulating a digit as a begin and end
 *  100ms */
#define AST_DEFAULT_EMULATE_DTMF_DURATION 100

#define DEFAULT_AMA_FLAGS AST_AMA_DOCUMENTATION

/*! Minimum amount of time between the end of the last digit and the beginning
 *  of a new one - 45ms */
#define AST_MIN_DTMF_GAP 45

/*! \brief List of channel drivers */
struct chanlist {
   const struct ast_channel_tech *tech;
   AST_LIST_ENTRY(chanlist) list;
};

/*! \brief the list of registered channel types */
static AST_RWLIST_HEAD_STATIC(backends, chanlist);

/*! \brief All active channels on the system */
static struct ao2_container *channels;

/*! \brief map AST_CAUSE's to readable string representations
 *
 * \ref causes.h
*/
struct causes_map {
   int cause;
   const char *name;
   const char *desc;
};

static const struct causes_map causes[] = {
   { AST_CAUSE_UNALLOCATED, "UNALLOCATED", "Unallocated (unassigned) number" },
   { AST_CAUSE_NO_ROUTE_TRANSIT_NET, "NO_ROUTE_TRANSIT_NET", "No route to specified transmit network" },
   { AST_CAUSE_NO_ROUTE_DESTINATION, "NO_ROUTE_DESTINATION", "No route to destination" },
   { AST_CAUSE_MISDIALLED_TRUNK_PREFIX, "MISDIALLED_TRUNK_PREFIX", "Misdialed trunk prefix" },
   { AST_CAUSE_CHANNEL_UNACCEPTABLE, "CHANNEL_UNACCEPTABLE", "Channel unacceptable" },
   { AST_CAUSE_CALL_AWARDED_DELIVERED, "CALL_AWARDED_DELIVERED", "Call awarded and being delivered in an established channel" },
   { AST_CAUSE_PRE_EMPTED, "PRE_EMPTED", "Pre-empted" },
   { AST_CAUSE_NUMBER_PORTED_NOT_HERE, "NUMBER_PORTED_NOT_HERE", "Number ported elsewhere" },
   { AST_CAUSE_NORMAL_CLEARING, "NORMAL_CLEARING", "Normal Clearing" },
   { AST_CAUSE_USER_BUSY, "USER_BUSY", "User busy" },
   { AST_CAUSE_NO_USER_RESPONSE, "NO_USER_RESPONSE", "No user responding" },
   { AST_CAUSE_NO_ANSWER, "NO_ANSWER", "User alerting, no answer" },
   { AST_CAUSE_SUBSCRIBER_ABSENT, "SUBSCRIBER_ABSENT", "Subscriber absent" },
   { AST_CAUSE_CALL_REJECTED, "CALL_REJECTED", "Call Rejected" },
   { AST_CAUSE_NUMBER_CHANGED, "NUMBER_CHANGED", "Number changed" },
   { AST_CAUSE_REDIRECTED_TO_NEW_DESTINATION, "REDIRECTED_TO_NEW_DESTINATION", "Redirected to new destination" },
   { AST_CAUSE_ANSWERED_ELSEWHERE, "ANSWERED_ELSEWHERE", "Answered elsewhere" },
   { AST_CAUSE_DESTINATION_OUT_OF_ORDER, "DESTINATION_OUT_OF_ORDER", "Destination out of order" },
   { AST_CAUSE_INVALID_NUMBER_FORMAT, "INVALID_NUMBER_FORMAT", "Invalid number format" },
   { AST_CAUSE_FACILITY_REJECTED, "FACILITY_REJECTED", "Facility rejected" },
   { AST_CAUSE_RESPONSE_TO_STATUS_ENQUIRY, "RESPONSE_TO_STATUS_ENQUIRY", "Response to STATus ENQuiry" },
   { AST_CAUSE_NORMAL_UNSPECIFIED, "NORMAL_UNSPECIFIED", "Normal, unspecified" },
   { AST_CAUSE_NORMAL_CIRCUIT_CONGESTION, "NORMAL_CIRCUIT_CONGESTION", "Circuit/channel congestion" },
   { AST_CAUSE_NETWORK_OUT_OF_ORDER, "NETWORK_OUT_OF_ORDER", "Network out of order" },
   { AST_CAUSE_NORMAL_TEMPORARY_FAILURE, "NORMAL_TEMPORARY_FAILURE", "Temporary failure" },
   { AST_CAUSE_SWITCH_CONGESTION, "SWITCH_CONGESTION", "Switching equipment congestion" },
   { AST_CAUSE_ACCESS_INFO_DISCARDED, "ACCESS_INFO_DISCARDED", "Access information discarded" },
   { AST_CAUSE_REQUESTED_CHAN_UNAVAIL, "REQUESTED_CHAN_UNAVAIL", "Requested channel not available" },
   { AST_CAUSE_FACILITY_NOT_SUBSCRIBED, "FACILITY_NOT_SUBSCRIBED", "Facility not subscribed" },
   { AST_CAUSE_OUTGOING_CALL_BARRED, "OUTGOING_CALL_BARRED", "Outgoing call barred" },
   { AST_CAUSE_INCOMING_CALL_BARRED, "INCOMING_CALL_BARRED", "Incoming call barred" },
   { AST_CAUSE_BEARERCAPABILITY_NOTAUTH, "BEARERCAPABILITY_NOTAUTH", "Bearer capability not authorized" },
   { AST_CAUSE_BEARERCAPABILITY_NOTAVAIL, "BEARERCAPABILITY_NOTAVAIL", "Bearer capability not available" },
   { AST_CAUSE_BEARERCAPABILITY_NOTIMPL, "BEARERCAPABILITY_NOTIMPL", "Bearer capability not implemented" },
   { AST_CAUSE_CHAN_NOT_IMPLEMENTED, "CHAN_NOT_IMPLEMENTED", "Channel not implemented" },
   { AST_CAUSE_FACILITY_NOT_IMPLEMENTED, "FACILITY_NOT_IMPLEMENTED", "Facility not implemented" },
   { AST_CAUSE_INVALID_CALL_REFERENCE, "INVALID_CALL_REFERENCE", "Invalid call reference value" },
   { AST_CAUSE_INCOMPATIBLE_DESTINATION, "INCOMPATIBLE_DESTINATION", "Incompatible destination" },
   { AST_CAUSE_INVALID_MSG_UNSPECIFIED, "INVALID_MSG_UNSPECIFIED", "Invalid message unspecified" },
   { AST_CAUSE_MANDATORY_IE_MISSING, "MANDATORY_IE_MISSING", "Mandatory information element is missing" },
   { AST_CAUSE_MESSAGE_TYPE_NONEXIST, "MESSAGE_TYPE_NONEXIST", "Message type nonexist." },
   { AST_CAUSE_WRONG_MESSAGE, "WRONG_MESSAGE", "Wrong message" },
   { AST_CAUSE_IE_NONEXIST, "IE_NONEXIST", "Info. element nonexist or not implemented" },
   { AST_CAUSE_INVALID_IE_CONTENTS, "INVALID_IE_CONTENTS", "Invalid information element contents" },
   { AST_CAUSE_WRONG_CALL_STATE, "WRONG_CALL_STATE", "Message not compatible with call state" },
   { AST_CAUSE_RECOVERY_ON_TIMER_EXPIRE, "RECOVERY_ON_TIMER_EXPIRE", "Recover on timer expiry" },
   { AST_CAUSE_MANDATORY_IE_LENGTH_ERROR, "MANDATORY_IE_LENGTH_ERROR", "Mandatory IE length error" },
   { AST_CAUSE_PROTOCOL_ERROR, "PROTOCOL_ERROR", "Protocol error, unspecified" },
   { AST_CAUSE_INTERWORKING, "INTERWORKING", "Interworking, unspecified" },
};

struct ast_variable *ast_channeltype_list(void)
{
   struct chanlist *cl;
   struct ast_variable *var = NULL, *prev = NULL;

   AST_RWLIST_RDLOCK(&backends);
   AST_RWLIST_TRAVERSE(&backends, cl, list) {
      if (prev)  {
         if ((prev->next = ast_variable_new(cl->tech->type, cl->tech->description, "")))
            prev = prev->next;
      } else {
         var = ast_variable_new(cl->tech->type, cl->tech->description, "");
         prev = var;
      }
   }
   AST_RWLIST_UNLOCK(&backends);

   return var;
}

#if defined(KEEP_TILL_CHANNEL_PARTY_NUMBER_INFO_NEEDED)
static const char *party_number_ton2str(int ton)
{
#if defined(HAVE_PRI)
   switch ((ton >> 4) & 0x07) {
   case PRI_TON_INTERNATIONAL:
      return "International";
   case PRI_TON_NATIONAL:
      return "National";
   case PRI_TON_NET_SPECIFIC:
      return "Network Specific";
   case PRI_TON_SUBSCRIBER:
      return "Subscriber";
   case PRI_TON_ABBREVIATED:
      return "Abbreviated";
   case PRI_TON_RESERVED:
      return "Reserved";
   case PRI_TON_UNKNOWN:
   default:
      break;
   }
#endif   /* defined(HAVE_PRI) */
   return "Unknown";
}
#endif   /* defined(KEEP_TILL_CHANNEL_PARTY_NUMBER_INFO_NEEDED) */

#if defined(KEEP_TILL_CHANNEL_PARTY_NUMBER_INFO_NEEDED)
static const char *party_number_plan2str(int plan)
{
#if defined(HAVE_PRI)
   switch (plan & 0x0F) {
   default:
   case PRI_NPI_UNKNOWN:
      break;
   case PRI_NPI_E163_E164:
      return "Public (E.163/E.164)";
   case PRI_NPI_X121:
      return "Data (X.121)";
   case PRI_NPI_F69:
      return "Telex (F.69)";
   case PRI_NPI_NATIONAL:
      return "National Standard";
   case PRI_NPI_PRIVATE:
      return "Private";
   case PRI_NPI_RESERVED:
      return "Reserved";
   }
#endif   /* defined(HAVE_PRI) */
   return "Unknown";
}
#endif   /* defined(KEEP_TILL_CHANNEL_PARTY_NUMBER_INFO_NEEDED) */

/*! \brief Show channel types - CLI command */
static char *handle_cli_core_show_channeltypes(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
#define FORMAT  "%-15.15s  %-40.40s %-13.13s %-13.13s %-13.13s %-13.13s\n"
   struct chanlist *cl;
   int count_chan = 0;

   switch (cmd) {
   case CLI_INIT:
      e->command = "core show channeltypes";
      e->usage =
         "Usage: core show channeltypes\n"
         "       Lists available channel types registered in your\n"
         "       Asterisk server.\n";
      return NULL;
   case CLI_GENERATE:
      return NULL;
   }

   if (a->argc != 3)
      return CLI_SHOWUSAGE;

   ast_cli(a->fd, FORMAT, "Type", "Description", "Devicestate", "Presencestate", "Indications", "Transfer");
   ast_cli(a->fd, FORMAT, "-------------", "-------------", "-------------", "-------------", "-------------", "-------------");

   AST_RWLIST_RDLOCK(&backends);
   AST_RWLIST_TRAVERSE(&backends, cl, list) {
      ast_cli(a->fd, FORMAT, cl->tech->type, cl->tech->description,
         (cl->tech->devicestate) ? "yes" : "no",
         (cl->tech->presencestate) ? "yes" : "no",
         (cl->tech->indicate) ? "yes" : "no",
         (cl->tech->transfer) ? "yes" : "no");
      count_chan++;
   }
   AST_RWLIST_UNLOCK(&backends);

   ast_cli(a->fd, "----------\n%d channel drivers registered.\n", count_chan);

   return CLI_SUCCESS;

#undef FORMAT
}

static char *complete_channeltypes(struct ast_cli_args *a)
{
   struct chanlist *cl;
   int wordlen;

   if (a->pos != 3) {
      return NULL;
   }

   wordlen = strlen(a->word);

   AST_RWLIST_RDLOCK(&backends);
   AST_RWLIST_TRAVERSE(&backends, cl, list) {
      if (!strncasecmp(a->word, cl->tech->type, wordlen)) {
         ast_cli_completion_add(ast_strdup(cl->tech->type));
      }
   }
   AST_RWLIST_UNLOCK(&backends);

   return NULL;
}

/*! \brief Show details about a channel driver - CLI command */
static char *handle_cli_core_show_channeltype(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
   struct chanlist *cl = NULL;
   struct ast_str *codec_buf = ast_str_alloca(AST_FORMAT_CAP_NAMES_LEN);

   switch (cmd) {
   case CLI_INIT:
      e->command = "core show channeltype";
      e->usage =
         "Usage: core show channeltype <name>\n"
         "  Show details about the specified channel type, <name>.\n";
      return NULL;
   case CLI_GENERATE:
      return complete_channeltypes(a);
   }

   if (a->argc != 4)
      return CLI_SHOWUSAGE;

   AST_RWLIST_RDLOCK(&backends);

   AST_RWLIST_TRAVERSE(&backends, cl, list) {
      if (!strncasecmp(cl->tech->type, a->argv[3], strlen(cl->tech->type)))
         break;
   }


   if (!cl) {
      ast_cli(a->fd, "\n%s is not a registered channel driver.\n", a->argv[3]);
      AST_RWLIST_UNLOCK(&backends);
      return CLI_FAILURE;
   }

   ast_cli(a->fd,
      "-- Info about channel driver: %s --\n"
      "  Device State: %s\n"
      "Presence State: %s\n"
      "    Indication: %s\n"
      "     Transfer : %s\n"
      "  Capabilities: %s\n"
      "   Digit Begin: %s\n"
      "     Digit End: %s\n"
      "    Send HTML : %s\n"
      " Image Support: %s\n"
      "  Text Support: %s\n",
      cl->tech->type,
      (cl->tech->devicestate) ? "yes" : "no",
      (cl->tech->presencestate) ? "yes" : "no",
      (cl->tech->indicate) ? "yes" : "no",
      (cl->tech->transfer) ? "yes" : "no",
      ast_format_cap_get_names(cl->tech->capabilities, &codec_buf),
      (cl->tech->send_digit_begin) ? "yes" : "no",
      (cl->tech->send_digit_end) ? "yes" : "no",
      (cl->tech->send_html) ? "yes" : "no",
      (cl->tech->send_image) ? "yes" : "no",
      (cl->tech->send_text) ? "yes" : "no"

   );

   AST_RWLIST_UNLOCK(&backends);

   return CLI_SUCCESS;
}

static struct ast_cli_entry cli_channel[] = {
   AST_CLI_DEFINE(handle_cli_core_show_channeltypes, "List available channel types"),
   AST_CLI_DEFINE(handle_cli_core_show_channeltype,  "Give more details on that channel type")
};

static struct ast_frame *kill_read(struct ast_channel *chan)
{
   /* Hangup channel. */
   return NULL;
}

static struct ast_frame *kill_exception(struct ast_channel *chan)
{
   /* Hangup channel. */
   return NULL;
}

static int kill_write(struct ast_channel *chan, struct ast_frame *frame)
{
   /* Hangup channel. */
   return -1;
}

static int kill_fixup(struct ast_channel *oldchan, struct ast_channel *newchan)
{
   /* No problem fixing up the channel. */
   return 0;
}

static int kill_hangup(struct ast_channel *chan)
{
   ast_channel_tech_pvt_set(chan, NULL);
   return 0;
}

/*!
 * \brief Kill the channel channel driver technology descriptor.
 *
 * \details
 * The purpose of this channel technology is to encourage the
 * channel to hangup as quickly as possible.
 *
 * \note Used by DTMF atxfer and zombie channels.
 */
const struct ast_channel_tech ast_kill_tech = {
   .type = "Kill",
   .description = "Kill channel (should not see this)",
   .read = kill_read,
   .exception = kill_exception,
   .write = kill_write,
   .fixup = kill_fixup,
   .hangup = kill_hangup,
};

/*! \brief Checks to see if a channel is needing hang up */
int ast_check_hangup(struct ast_channel *chan)
{
   if (ast_channel_softhangup_internal_flag(chan))    /* yes if soft hangup flag set */
      return 1;
   if (ast_tvzero(*ast_channel_whentohangup(chan)))   /* no if no hangup scheduled */
      return 0;
   if (ast_tvdiff_ms(*ast_channel_whentohangup(chan), ast_tvnow()) > 0)    /* no if hangup time has not come yet. */
      return 0;
   ast_debug(4, "Hangup time has come: %" PRIi64 "\n", ast_tvdiff_ms(*ast_channel_whentohangup(chan), ast_tvnow()));
   ast_test_suite_event_notify("HANGUP_TIME", "Channel: %s", ast_channel_name(chan));
   ast_channel_softhangup_internal_flag_add(chan, AST_SOFTHANGUP_TIMEOUT); /* record event */
   return 1;
}

int ast_check_hangup_locked(struct ast_channel *chan)
{
   int res;
   ast_channel_lock(chan);
   res = ast_check_hangup(chan);
   ast_channel_unlock(chan);
   return res;
}

void ast_channel_softhangup_withcause_locked(struct ast_channel *chan, int causecode)
{
   ast_channel_lock(chan);

   if (causecode > 0) {
      ast_debug(1, "Setting hangupcause of channel %s to %d (is %d now)\n",
         ast_channel_name(chan), causecode, ast_channel_hangupcause(chan));

      ast_channel_hangupcause_set(chan, causecode);
   }

   ast_softhangup_nolock(chan, AST_SOFTHANGUP_EXPLICIT);

   ast_channel_unlock(chan);
}

static int ast_channel_softhangup_cb(void *obj, void *arg, int flags)
{
   struct ast_channel *chan = obj;

   ast_softhangup(chan, AST_SOFTHANGUP_SHUTDOWN);

   return 0;
}

void ast_softhangup_all(void)
{
   ao2_callback(channels, OBJ_NODATA | OBJ_MULTIPLE, ast_channel_softhangup_cb, NULL);
}

/*! \brief returns number of active/allocated channels */
int ast_active_channels(void)
{
   return channels ? ao2_container_count(channels) : 0;
}

int ast_undestroyed_channels(void)
{
   return ast_atomic_fetchadd_int(&chancount, 0);
}

/*! \brief Set when to hangup channel */
void ast_channel_setwhentohangup_tv(struct ast_channel *chan, struct timeval offset)
{
   if (ast_tvzero(offset)) {
      ast_channel_whentohangup_set(chan, &offset);
   } else {
      struct timeval tv = ast_tvadd(offset, ast_tvnow());
      ast_channel_whentohangup_set(chan, &tv);
   }
   ast_queue_frame(chan, &ast_null_frame);
   return;
}

/*! \brief Compare a offset with when to hangup channel */
int ast_channel_cmpwhentohangup_tv(struct ast_channel *chan, struct timeval offset)
{
   struct timeval whentohangup;

   if (ast_tvzero(*ast_channel_whentohangup(chan)))
      return ast_tvzero(offset) ? 0 : -1;

   if (ast_tvzero(offset))
      return 1;

   whentohangup = ast_tvadd(offset, ast_tvnow());

   return ast_tvdiff_ms(whentohangup, *ast_channel_whentohangup(chan));
}

/*! \brief Register a new telephony channel in Asterisk */
int ast_channel_register(const struct ast_channel_tech *tech)
{
   struct chanlist *chan;

   AST_RWLIST_WRLOCK(&backends);

   AST_RWLIST_TRAVERSE(&backends, chan, list) {
      if (!strcasecmp(tech->type, chan->tech->type)) {
         ast_log(LOG_WARNING, "Already have a handler for type '%s'\n", tech->type);
         AST_RWLIST_UNLOCK(&backends);
         return -1;
      }
   }

   if (!(chan = ast_calloc(1, sizeof(*chan)))) {
      AST_RWLIST_UNLOCK(&backends);
      return -1;
   }
   chan->tech = tech;
   AST_RWLIST_INSERT_HEAD(&backends, chan, list);

   ast_debug(1, "Registered handler for '%s' (%s)\n", chan->tech->type, chan->tech->description);

   ast_verb(2, "Registered channel type '%s' (%s)\n", chan->tech->type, chan->tech->description);

   AST_RWLIST_UNLOCK(&backends);

   return 0;
}

/*! \brief Unregister channel driver */
void ast_channel_unregister(const struct ast_channel_tech *tech)
{
   struct chanlist *chan;

   ast_debug(1, "Unregistering channel type '%s'\n", tech->type);

   AST_RWLIST_WRLOCK(&backends);

   AST_RWLIST_TRAVERSE_SAFE_BEGIN(&backends, chan, list) {
      if (chan->tech == tech) {
         AST_LIST_REMOVE_CURRENT(list);
         ast_free(chan);
         ast_verb(2, "Unregistered channel type '%s'\n", tech->type);
         break;
      }
   }
   AST_LIST_TRAVERSE_SAFE_END;

   AST_RWLIST_UNLOCK(&backends);
}

/*! \brief Get handle to channel driver based on name */
const struct ast_channel_tech *ast_get_channel_tech(const char *name)
{
   struct chanlist *chanls;
   const struct ast_channel_tech *ret = NULL;

   AST_RWLIST_RDLOCK(&backends);

   AST_RWLIST_TRAVERSE(&backends, chanls, list) {
      if (!strcasecmp(name, chanls->tech->type)) {
         ret = chanls->tech;
         break;
      }
   }

   AST_RWLIST_UNLOCK(&backends);

   return ret;
}

/*! \brief Gives the string form of a given hangup cause */
const char *ast_cause2str(int cause)
{
   int x;

   for (x = 0; x < ARRAY_LEN(causes); x++) {
      if (causes[x].cause == cause)
         return causes[x].desc;
   }

   return "Unknown";
}

/*! \brief Convert a symbolic hangup cause to number */
int ast_str2cause(const char *name)
{
   int x;

   for (x = 0; x < ARRAY_LEN(causes); x++)
      if (!strncasecmp(causes[x].name, name, strlen(causes[x].name)))
         return causes[x].cause;

   return -1;
}

/*! \brief Gives the string form of a given channel state.
 *
 * \note This function is not reentrant.
 *
 * \param state
 */
const char *ast_state2str(enum ast_channel_state state)
{
   char *buf;

   switch (state) {
   case AST_STATE_DOWN:
      return "Down";
   case AST_STATE_RESERVED:
      return "Rsrvd";
   case AST_STATE_OFFHOOK:
      return "OffHook";
   case AST_STATE_DIALING:
      return "Dialing";
   case AST_STATE_RING:
      return "Ring";
   case AST_STATE_RINGING:
      return "Ringing";
   case AST_STATE_UP:
      return "Up";
   case AST_STATE_BUSY:
      return "Busy";
   case AST_STATE_DIALING_OFFHOOK:
      return "Dialing Offhook";
   case AST_STATE_PRERING:
      return "Pre-ring";
   case AST_STATE_MUTE:
      return "Mute";
   default:
      if (!(buf = ast_threadstorage_get(&state2str_threadbuf, STATE2STR_BUFSIZE)))
         return "Unknown";
      snprintf(buf, STATE2STR_BUFSIZE, "Unknown (%u)", state);
      return buf;
   }
}

/*! \brief Gives the string form of a given transfer capability */
char *ast_transfercapability2str(int transfercapability)
{
   switch (transfercapability) {
   case AST_TRANS_CAP_SPEECH:
      return "SPEECH";
   case AST_TRANS_CAP_DIGITAL:
      return "DIGITAL";
   case AST_TRANS_CAP_RESTRICTED_DIGITAL:
      return "RESTRICTED_DIGITAL";
   case AST_TRANS_CAP_3_1K_AUDIO:
      return "3K1AUDIO";
   case AST_TRANS_CAP_DIGITAL_W_TONES:
      return "DIGITAL_W_TONES";
   case AST_TRANS_CAP_VIDEO:
      return "VIDEO";
   default:
      return "UNKNOWN";
   }
}

/*! \brief Channel technology used to extract a channel from a running application. The
 * channel created with this technology will be immediately hung up - most external
 * applications won't ever want to see this.
 */
static const struct ast_channel_tech surrogate_tech = {
   .type = "Surrogate",
   .description = "Surrogate channel used to pull channel from an application",
   .properties = AST_CHAN_TP_INTERNAL,
};

static const struct ast_channel_tech null_tech = {
   .type = "NULL",
   .description = "Null channel (should not see this)",
};

static void ast_channel_destructor(void *obj);
static void ast_dummy_channel_destructor(void *obj);
static int ast_channel_by_uniqueid_cb(void *obj, void *arg, void *data, int flags);

static int does_id_conflict(const char *uniqueid)
{
   struct ast_channel *conflict;
   size_t length = 0;

   if (ast_strlen_zero(uniqueid)) {
      return 0;
   }

   conflict = ast_channel_callback(ast_channel_by_uniqueid_cb, (char *) uniqueid, &length, OBJ_NOLOCK);
   if (conflict) {
      ast_log(LOG_ERROR, "Channel Unique ID '%s' already in use by channel %s(%p)\n",
         uniqueid, ast_channel_name(conflict), conflict);
      ast_channel_unref(conflict);
      return 1;
   }

   return 0;
}

/*! \brief Create a new channel structure */
static struct ast_channel *__attribute__((format(printf, 15, 0)))
__ast_channel_alloc_ap(int needqueue, int state, const char *cid_num, const char *cid_name,
             const char *acctcode, const char *exten, const char *context, const struct ast_assigned_ids *assignedids,
             const struct ast_channel *requestor, enum ama_flags amaflag, struct ast_endpoint *endpoint,
             const char *file, int line,
             const char *function, const char *name_fmt, va_list ap)
{
   struct ast_channel *tmp;
   struct varshead *headp;
   char *tech = "", *tech2 = NULL;
   struct ast_format_cap *nativeformats;
   struct ast_sched_context *schedctx;
   struct ast_timer *timer;
   struct timeval now;
   const struct ast_channel_tech *channel_tech;
   struct ast_stream_topology *topology;

   /* If shutting down, don't allocate any new channels */
   if (ast_shutting_down()) {
      ast_log(LOG_WARNING, "Channel allocation failed: Refusing due to active shutdown\n");
      return NULL;
   }

   tmp = __ast_channel_internal_alloc(ast_channel_destructor, assignedids, requestor,
      file, line, function);
   if (!tmp) {
      /* Channel structure allocation failure. */
      return NULL;
   }

   ast_channel_stage_snapshot(tmp);

   /*
    * Init file descriptors to unopened state so
    * the destructor can know not to close them.
    */
   ast_channel_timingfd_set(tmp, -1);
   ast_channel_internal_alertpipe_clear(tmp);
   ast_channel_internal_fd_clear_all(tmp);

   nativeformats = ast_format_cap_alloc(AST_FORMAT_CAP_FLAG_DEFAULT);
   if (!nativeformats) {
      /*
       * Aborting the channel creation.  We do not need to complete staging
       * the channel snapshot because the channel has not been finalized or
       * linked into the channels container yet.  Nobody else knows about
       * this channel nor will anybody ever know about it.
       */
      return ast_channel_unref(tmp);
   }
   ast_format_cap_append(nativeformats, ast_format_none, 0);
   ast_channel_nativeformats_set(tmp, nativeformats);
   ao2_ref(nativeformats, -1);

   ast_channel_set_rawwriteformat(tmp, ast_format_none);
   ast_channel_set_rawreadformat(tmp, ast_format_none);
   ast_channel_set_writeformat(tmp, ast_format_none);
   ast_channel_set_readformat(tmp, ast_format_none);

   if (!(schedctx = ast_sched_context_create())) {
      ast_log(LOG_WARNING, "Channel allocation failed: Unable to create schedule context\n");
      /* See earlier channel creation abort comment above. */
      return ast_channel_unref(tmp);
   }
   ast_channel_sched_set(tmp, schedctx);

   ast_party_dialed_init(ast_channel_dialed(tmp));
   ast_party_caller_init(ast_channel_caller(tmp));
   ast_party_connected_line_init(ast_channel_connected(tmp));
   ast_party_connected_line_init(ast_channel_connected_indicated(tmp));
   ast_party_redirecting_init(ast_channel_redirecting(tmp));

   if (cid_name) {
      ast_channel_caller(tmp)->id.name.valid = 1;
      ast_channel_caller(tmp)->id.name.str = ast_strdup(cid_name);
      if (!ast_channel_caller(tmp)->id.name.str) {
         /* See earlier channel creation abort comment above. */
         return ast_channel_unref(tmp);
      }
   }
   if (cid_num) {
      ast_channel_caller(tmp)->id.number.valid = 1;
      ast_channel_caller(tmp)->id.number.str = ast_strdup(cid_num);
      if (!ast_channel_caller(tmp)->id.number.str) {
         /* See earlier channel creation abort comment above. */
         return ast_channel_unref(tmp);
      }
   }

   if ((timer = ast_timer_open())) {
      ast_channel_timer_set(tmp, timer);
      if (strcmp(ast_timer_get_name(ast_channel_timer(tmp)), "timerfd")) {
         needqueue = 0;
      }
      ast_channel_timingfd_set(tmp, ast_timer_fd(ast_channel_timer(tmp)));
   }

   if (needqueue && ast_channel_internal_alertpipe_init(tmp)) {
      /* See earlier channel creation abort comment above. */
      return ast_channel_unref(tmp);
   }

   if (!(topology = ast_stream_topology_alloc())) {
      return ast_channel_unref(tmp);
   }
   ast_channel_internal_set_stream_topology(tmp, topology);

   /* Always watch the alertpipe */
   ast_channel_set_fd(tmp, AST_ALERT_FD, ast_channel_internal_alert_readfd(tmp));
   /* And timing pipe */
   ast_channel_set_fd(tmp, AST_TIMING_FD, ast_channel_timingfd(tmp));

   /* Initial state */
   ast_channel_state_set(tmp, state);
   ast_channel_hold_state_set(tmp, AST_CONTROL_UNHOLD);

   ast_channel_streamid_set(tmp, -1);
   ast_channel_vstreamid_set(tmp, -1);

   ast_channel_fin_set(tmp, global_fin);
   ast_channel_fout_set(tmp, global_fout);

   now = ast_tvnow();
   ast_channel_creationtime_set(tmp, &now);

   ast_channel_internal_setup_topics(tmp);

   if (!ast_strlen_zero(name_fmt)) {
      char *slash, *slash2;
      /* Almost every channel is calling this function, and setting the name via the ast_string_field_build() call.
       * And they all use slightly different formats for their name string.
       * This means, to set the name here, we have to accept variable args, and call the string_field_build from here.
       * This means, that the stringfields must have a routine that takes the va_lists directly, and
       * uses them to build the string, instead of forming the va_lists internally from the vararg ... list.
       * This new function was written so this can be accomplished.
       */
      ast_channel_name_build_va(tmp, name_fmt, ap);
      tech = ast_strdupa(ast_channel_name(tmp));
      if ((slash = strchr(tech, '/'))) {
         if ((slash2 = strchr(slash + 1, '/'))) {
            tech2 = slash + 1;
            *slash2 = '\0';
         }
         *slash = '\0';
      }
   } else {
      /*
       * Start the string with '-' so it becomes an empty string
       * in the destructor.
       */
      ast_channel_name_set(tmp, "-**Unknown**");
   }

   if (amaflag != AST_AMA_NONE) {
      ast_channel_amaflags_set(tmp, amaflag);
   } else {
      ast_channel_amaflags_set(tmp, DEFAULT_AMA_FLAGS);
   }

   if (!ast_strlen_zero(acctcode)) {
      ast_channel_accountcode_set(tmp, acctcode);
   }
   ast_channel_language_set(tmp, ast_defaultlanguage);

   ast_channel_context_set(tmp, S_OR(context, "default"));
   ast_channel_exten_set(tmp, S_OR(exten, "s"));
   ast_channel_priority_set(tmp, 1);

   headp = ast_channel_varshead(tmp);
   AST_LIST_HEAD_INIT_NOLOCK(headp);

   ast_pbx_hangup_handler_init(tmp);
   AST_LIST_HEAD_INIT_NOLOCK(ast_channel_datastores(tmp));
   AST_LIST_HEAD_INIT_NOLOCK(ast_channel_autochans(tmp));

   channel_tech = ast_get_channel_tech(tech);
   if (!channel_tech && !ast_strlen_zero(tech2)) {
      channel_tech = ast_get_channel_tech(tech2);
   }
   if (channel_tech) {
      ast_channel_tech_set(tmp, channel_tech);
   } else {
      ast_channel_tech_set(tmp, &null_tech);
   }

   /* You might scream "locking inversion" at seeing this but it is actually perfectly fine.
    * Since the channel was just created nothing can know about it yet or even acquire it.
    */
   ast_channel_lock(tmp);

   ao2_lock(channels);

   if (assignedids && (does_id_conflict(assignedids->uniqueid) || does_id_conflict(assignedids->uniqueid2))) {
      ast_channel_internal_errno_set(AST_CHANNEL_ERROR_ID_EXISTS);
      ao2_unlock(channels);
      ast_channel_unlock(tmp);
      /* See earlier channel creation abort comment above. */
      return ast_channel_unref(tmp);
   }

   /* Finalize and link into the channels container. */
   ast_channel_internal_finalize(tmp);
   ast_atomic_fetchadd_int(&chancount, +1);
   ao2_link_flags(channels, tmp, OBJ_NOLOCK);

   ao2_unlock(channels);

   if (endpoint) {
      ast_endpoint_add_channel(endpoint, tmp);
   }

   /*
    * And now, since the channel structure is built, and has its name, let
    * the world know of its existance
    */
   ast_channel_stage_snapshot_done(tmp);

   ast_debug(1, "Channel %p '%s' allocated\n", tmp, ast_channel_name(tmp));

   return tmp;
}

struct ast_channel *__ast_channel_alloc(int needqueue, int state, const char *cid_num,
               const char *cid_name, const char *acctcode,
               const char *exten, const char *context, const struct ast_assigned_ids *assignedids,
               const struct ast_channel *requestor, enum ama_flags amaflag,
               struct ast_endpoint *endpoint,
               const char *file, int line, const char *function,
               const char *name_fmt, ...)
{
   va_list ap;
   struct ast_channel *result;

   va_start(ap, name_fmt);
   result = __ast_channel_alloc_ap(needqueue, state, cid_num, cid_name, acctcode, exten, context,
               assignedids, requestor, amaflag, endpoint, file, line, function, name_fmt, ap);
   va_end(ap);

   return result;
}

/* only do the minimum amount of work needed here to make a channel
 * structure that can be used to expand channel vars */
struct ast_channel *__ast_dummy_channel_alloc(const char *file, int line, const char *function)
{
   struct ast_channel *tmp;
   struct varshead *headp;

   tmp = __ast_channel_internal_alloc(ast_dummy_channel_destructor, NULL, NULL,
      file, line, function);
   if (!tmp) {
      /* Dummy channel structure allocation failure. */
      return NULL;
   }

   ast_pbx_hangup_handler_init(tmp);
   AST_LIST_HEAD_INIT_NOLOCK(ast_channel_datastores(tmp));

   /*
    * Init file descriptors to unopened state just in case
    * autoservice is called on the channel or something tries to
    * read a frame from it.
    */
   ast_channel_timingfd_set(tmp, -1);
   ast_channel_internal_alertpipe_clear(tmp);
   ast_channel_internal_fd_clear_all(tmp);

   ast_channel_hold_state_set(tmp, AST_CONTROL_UNHOLD);

   ast_channel_internal_setup_topics(tmp);

   headp = ast_channel_varshead(tmp);
   AST_LIST_HEAD_INIT_NOLOCK(headp);

   return tmp;
}

static int __ast_queue_frame(struct ast_channel *chan, struct ast_frame *fin, int head, struct ast_frame *after)
{
   struct ast_frame *f;
   struct ast_frame *cur;
   unsigned int new_frames = 0;
   unsigned int new_voice_frames = 0;
   unsigned int queued_frames = 0;
   unsigned int queued_voice_frames = 0;
   AST_LIST_HEAD_NOLOCK(,ast_frame) frames;

   ast_channel_lock(chan);

   /*
    * Check the last frame on the queue if we are queuing the new
    * frames after it.
    */
   cur = AST_LIST_LAST(ast_channel_readq(chan));
   if (cur && cur->frametype == AST_FRAME_CONTROL && !head && (!after || after == cur)) {
      switch (cur->subclass.integer) {
      case AST_CONTROL_END_OF_Q:
         if (fin->frametype == AST_FRAME_CONTROL
            && fin->subclass.integer == AST_CONTROL_HANGUP) {
            /*
             * Destroy the end-of-Q marker frame so we can queue the hangup
             * frame in its place.
             */
            AST_LIST_REMOVE(ast_channel_readq(chan), cur, frame_list);
            ast_frfree(cur);

            /*
             * This has degenerated to a normal queue append anyway.  Since
             * we just destroyed the last frame in the queue we must make
             * sure that "after" is NULL or bad things will happen.
             */
            after = NULL;
            break;
         }
         /* Fall through */
      case AST_CONTROL_HANGUP:
         /* Don't queue anything. */
         ast_channel_unlock(chan);
         return 0;
      default:
         break;
      }
   }

   /* Build copies of all the new frames and count them */
   AST_LIST_HEAD_INIT_NOLOCK(&frames);
   for (cur = fin; cur; cur = AST_LIST_NEXT(cur, frame_list)) {
      if (!(f = ast_frdup(cur))) {
         if (AST_LIST_FIRST(&frames)) {
            ast_frfree(AST_LIST_FIRST(&frames));
         }
         ast_channel_unlock(chan);
         return -1;
      }

      AST_LIST_INSERT_TAIL(&frames, f, frame_list);
      new_frames++;
      if (f->frametype == AST_FRAME_VOICE) {
         new_voice_frames++;
      }
   }

   /* Count how many frames exist on the queue */
   AST_LIST_TRAVERSE(ast_channel_readq(chan), cur, frame_list) {
      queued_frames++;
      if (cur->frametype == AST_FRAME_VOICE) {
         queued_voice_frames++;
      }
   }

   if ((queued_frames + new_frames > 128 || queued_voice_frames + new_voice_frames > 96)) {
      int count = 0;
      ast_log(LOG_WARNING, "Exceptionally long %squeue length queuing to %s\n", queued_frames + new_frames > 128 ? "" : "voice ", ast_channel_name(chan));
      AST_LIST_TRAVERSE_SAFE_BEGIN(ast_channel_readq(chan), cur, frame_list) {
         /* Save the most recent frame */
         if (!AST_LIST_NEXT(cur, frame_list)) {
            break;
         } else if (cur->frametype == AST_FRAME_VOICE || cur->frametype == AST_FRAME_VIDEO || cur->frametype == AST_FRAME_NULL) {
            if (++count > 64) {
               break;
            }
            AST_LIST_REMOVE_CURRENT(frame_list);
            ast_frfree(cur);

            /* Read from the alert pipe for each flushed frame. */
            ast_channel_internal_alert_read(chan);
         }
      }
      AST_LIST_TRAVERSE_SAFE_END;
   }

   if (after) {
      AST_LIST_INSERT_LIST_AFTER(ast_channel_readq(chan), &frames, after, frame_list);
   } else {
      if (head) {
         AST_LIST_APPEND_LIST(&frames, ast_channel_readq(chan), frame_list);
         AST_LIST_HEAD_INIT_NOLOCK(ast_channel_readq(chan));
      }
      AST_LIST_APPEND_LIST(ast_channel_readq(chan), &frames, frame_list);
   }

   if (ast_channel_alert_writable(chan)) {
      /* Write to the alert pipe for each added frame */
      while (new_frames--) {
         if (ast_channel_alert_write(chan)) {
            ast_log(LOG_WARNING, "Unable to write to alert pipe on %s (qlen = %u): %s!\n",
               ast_channel_name(chan), queued_frames, strerror(errno));
            break;
         }
      }
   } else if (ast_channel_timingfd(chan) > -1) {
      ast_timer_enable_continuous(ast_channel_timer(chan));
   } else if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_BLOCKING)) {
      pthread_kill(ast_channel_blocker(chan), SIGURG);
   }

   ast_channel_unlock(chan);

   return 0;
}

int ast_queue_frame(struct ast_channel *chan, struct ast_frame *fin)
{
   return __ast_queue_frame(chan, fin, 0, NULL);
}

int ast_queue_frame_head(struct ast_channel *chan, struct ast_frame *fin)
{
   return __ast_queue_frame(chan, fin, 1, NULL);
}

/*! \brief Queue a hangup frame for channel */
int ast_queue_hangup(struct ast_channel *chan)
{
   struct ast_frame f = { AST_FRAME_CONTROL, .subclass.integer = AST_CONTROL_HANGUP };
   int res;

   /* Yeah, let's not change a lock-critical value without locking */
   ast_channel_lock(chan);
   ast_channel_softhangup_internal_flag_add(chan, AST_SOFTHANGUP_DEV);
   ast_channel_publish_blob(chan, ast_channel_hangup_request_type(), NULL);

   res = ast_queue_frame(chan, &f);
   ast_channel_unlock(chan);
   return res;
}

/*! \brief Queue a hangup frame for channel */
int ast_queue_hangup_with_cause(struct ast_channel *chan, int cause)
{
   RAII_VAR(struct ast_json *, blob, NULL, ast_json_unref);
   struct ast_frame f = { AST_FRAME_CONTROL, .subclass.integer = AST_CONTROL_HANGUP };
   int res;

   if (cause >= 0) {
      f.data.uint32 = cause;
   }

   /* Yeah, let's not change a lock-critical value without locking */
   ast_channel_lock(chan);
   ast_channel_softhangup_internal_flag_add(chan, AST_SOFTHANGUP_DEV);
   if (cause < 0) {
      f.data.uint32 = ast_channel_hangupcause(chan);
   }
   blob = ast_json_pack("{s: i}",
              "cause", cause);
   ast_channel_publish_blob(chan, ast_channel_hangup_request_type(), blob);

   res = ast_queue_frame(chan, &f);
   ast_channel_unlock(chan);
   return res;
}

int ast_queue_hold(struct ast_channel *chan, const char *musicclass)
{
   struct ast_frame f = { AST_FRAME_CONTROL, .subclass.integer = AST_CONTROL_HOLD };
   struct ast_json *blob = NULL;
   int res;

   if (!ast_strlen_zero(musicclass)) {
      f.data.ptr = (void *) musicclass;
      f.datalen = strlen(musicclass) + 1;

      blob = ast_json_pack("{s: s}",
                 "musicclass", musicclass);
   }

   ast_channel_lock(chan);
   ast_channel_publish_blob(chan, ast_channel_hold_type(), blob);
   ast_channel_unlock(chan);

   res = ast_queue_frame(chan, &f);

   ast_json_unref(blob);

   return res;
}

int ast_queue_unhold(struct ast_channel *chan)
{
   struct ast_frame f = { AST_FRAME_CONTROL, .subclass.integer = AST_CONTROL_UNHOLD };
   int res;

   ast_channel_lock(chan);
   ast_channel_publish_blob(chan, ast_channel_unhold_type(), NULL);
   ast_channel_unlock(chan);

   res = ast_queue_frame(chan, &f);

   return res;
}

/*! \brief Queue a control frame */
int ast_queue_control(struct ast_channel *chan, enum ast_control_frame_type control)
{
   struct ast_frame f = { AST_FRAME_CONTROL, .subclass.integer = control };
   return ast_queue_frame(chan, &f);
}

/*! \brief Queue a control frame with payload */
int ast_queue_control_data(struct ast_channel *chan, enum ast_control_frame_type control,
            const void *data, size_t datalen)
{
   struct ast_frame f = { AST_FRAME_CONTROL, .subclass.integer = control, .data.ptr = (void *) data, .datalen = datalen };
   return ast_queue_frame(chan, &f);
}

/*! \brief Queue an ANSWER control frame with topology */
int ast_queue_answer(struct ast_channel *chan, const struct ast_stream_topology *topology)
{
   struct ast_frame f = {
      AST_FRAME_CONTROL,
      .subclass.integer = AST_CONTROL_ANSWER,
      .subclass.topology = (struct ast_stream_topology *)topology,
   };
   return ast_queue_frame(chan, &f);
}

/*! \brief Set defer DTMF flag on channel */
int ast_channel_defer_dtmf(struct ast_channel *chan)
{
   int pre = 0;

   if (chan) {
      ast_channel_lock(chan);
      pre = ast_test_flag(ast_channel_flags(chan), AST_FLAG_DEFER_DTMF);
      ast_set_flag(ast_channel_flags(chan), AST_FLAG_DEFER_DTMF);
      ast_channel_unlock(chan);
   }
   return pre;
}

/*! \brief Unset defer DTMF flag on channel */
void ast_channel_undefer_dtmf(struct ast_channel *chan)
{
   if (chan) {
      ast_channel_clear_flag(chan, AST_FLAG_DEFER_DTMF);
   }
}

struct ast_channel *ast_channel_callback(ao2_callback_data_fn *cb_fn, void *arg,
      void *data, int ao2_flags)
{
   return ao2_callback_data(channels, ao2_flags, cb_fn, arg, data);
}

static int ast_channel_by_name_cb(void *obj, void *arg, void *data, int flags)
{
   struct ast_channel *chan = obj;
   const char *name = arg;
   size_t name_len = *(size_t *) data;
   int ret = CMP_MATCH;

   if (ast_strlen_zero(name)) {
      ast_log(LOG_ERROR, "BUG! Must supply a channel name or partial name to match!\n");
      return CMP_STOP;
   }

   ast_channel_lock(chan);
   if ((!name_len && strcasecmp(ast_channel_name(chan), name))
      || (name_len && strncasecmp(ast_channel_name(chan), name, name_len))) {
      ret = 0; /* name match failed, keep looking */
   }
   ast_channel_unlock(chan);

   return ret;
}

static int ast_channel_by_exten_cb(void *obj, void *arg, void *data, int flags)
{
   struct ast_channel *chan = obj;
   char *context = arg;
   char *exten = data;
   int ret = CMP_MATCH;

   if (ast_strlen_zero(exten) || ast_strlen_zero(context)) {
      ast_log(LOG_ERROR, "BUG! Must have a context and extension to match!\n");
      return CMP_STOP;
   }

   ast_channel_lock(chan);
   if (strcasecmp(ast_channel_context(chan), context) && strcasecmp(ast_channel_macrocontext(chan), context)) {
      ret = 0; /* Context match failed, continue */
   } else if (strcasecmp(ast_channel_exten(chan), exten) && strcasecmp(ast_channel_macroexten(chan), exten)) {
      ret = 0; /* Extension match failed, continue */
   }
   ast_channel_unlock(chan);

   return ret;
}

static int ast_channel_by_uniqueid_cb(void *obj, void *arg, void *data, int flags)
{
   struct ast_channel *chan = obj;
   char *uniqueid = arg;
   size_t id_len = *(size_t *) data;
   int ret = CMP_MATCH;

   if (ast_strlen_zero(uniqueid)) {
      ast_log(LOG_ERROR, "BUG! Must supply a uniqueid or partial uniqueid to match!\n");
      return CMP_STOP;
   }

   ast_channel_lock(chan);
   if ((!id_len && strcasecmp(ast_channel_uniqueid(chan), uniqueid))
      || (id_len && strncasecmp(ast_channel_uniqueid(chan), uniqueid, id_len))) {
      ret = 0; /* uniqueid match failed, keep looking */
   }
   ast_channel_unlock(chan);

   return ret;
}

struct ast_channel_iterator {
   /* storage for non-dynamically allocated iterator */
   struct ao2_iterator simple_iterator;
   /* pointer to the actual iterator (simple_iterator or a dynamically
    * allocated iterator)
    */
   struct ao2_iterator *active_iterator;
};

struct ast_channel_iterator *ast_channel_iterator_destroy(struct ast_channel_iterator *i)
{
   ao2_iterator_destroy(i->active_iterator);
   ast_free(i);

   return NULL;
}

struct ast_channel_iterator *ast_channel_iterator_by_exten_new(const char *exten, const char *context)
{
   struct ast_channel_iterator *i;
   char *l_exten = (char *) exten;
   char *l_context = (char *) context;

   if (!(i = ast_calloc(1, sizeof(*i)))) {
      return NULL;
   }

   i->active_iterator = (void *) ast_channel_callback(ast_channel_by_exten_cb,
      l_context, l_exten, OBJ_MULTIPLE);
   if (!i->active_iterator) {
      ast_free(i);
      return NULL;
   }

   return i;
}

struct ast_channel_iterator *ast_channel_iterator_by_name_new(const char *name, size_t name_len)
{
   struct ast_channel_iterator *i;
   char *l_name = (char *) name;

   if (!(i = ast_calloc(1, sizeof(*i)))) {
      return NULL;
   }

   i->active_iterator = (void *) ast_channel_callback(ast_channel_by_name_cb,
      l_name, &name_len,
      OBJ_MULTIPLE | (name_len == 0 /* match the whole word, so optimize */ ? OBJ_KEY : 0));
   if (!i->active_iterator) {
      ast_free(i);
      return NULL;
   }

   return i;
}

struct ast_channel_iterator *ast_channel_iterator_all_new(void)
{
   struct ast_channel_iterator *i;

   if (!(i = ast_calloc(1, sizeof(*i)))) {
      return NULL;
   }

   i->simple_iterator = ao2_iterator_init(channels, 0);
   i->active_iterator = &i->simple_iterator;

   return i;
}

struct ast_channel *ast_channel_iterator_next(struct ast_channel_iterator *i)
{
   return ao2_iterator_next(i->active_iterator);
}

/* Legacy function, not currently used for lookups, but we need a cmp_fn */
static int ast_channel_cmp_cb(void *obj, void *arg, int flags)
{
   ast_log(LOG_ERROR, "BUG! Should never be called!\n");
   return CMP_STOP;
}

struct ast_channel *ast_channel_get_by_name_prefix(const char *name, size_t name_len)
{
   struct ast_channel *chan;
   char *l_name = (char *) name;

   chan = ast_channel_callback(ast_channel_by_name_cb, l_name, &name_len,
      (name_len == 0) /* optimize if it is a complete name match */ ? OBJ_KEY : 0);
   if (chan) {
      return chan;
   }

   if (ast_strlen_zero(l_name)) {
      /* We didn't have a name to search for so quit. */
      return NULL;
   }

   /* Now try a search for uniqueid. */
   return ast_channel_callback(ast_channel_by_uniqueid_cb, l_name, &name_len, 0);
}

struct ast_channel *ast_channel_get_by_name(const char *name)
{
   return ast_channel_get_by_name_prefix(name, 0);
}

struct ast_channel *ast_channel_get_by_exten(const char *exten, const char *context)
{
   char *l_exten = (char *) exten;
   char *l_context = (char *) context;

   return ast_channel_callback(ast_channel_by_exten_cb, l_context, l_exten, 0);
}

int ast_is_deferrable_frame(const struct ast_frame *frame)
{
   /* Do not add a default entry in this switch statement.  Each new
    * frame type should be addressed directly as to whether it should
    * be queued up or not.
    */
   switch (frame->frametype) {
   case AST_FRAME_BRIDGE_ACTION:
   case AST_FRAME_BRIDGE_ACTION_SYNC:
   case AST_FRAME_CONTROL:
   case AST_FRAME_TEXT:
   case AST_FRAME_TEXT_DATA:
   case AST_FRAME_IMAGE:
   case AST_FRAME_HTML:
      return 1;

   case AST_FRAME_DTMF_END:
   case AST_FRAME_DTMF_BEGIN:
   case AST_FRAME_VOICE:
   case AST_FRAME_VIDEO:
   case AST_FRAME_NULL:
   case AST_FRAME_IAX:
   case AST_FRAME_CNG:
   case AST_FRAME_MODEM:
   case AST_FRAME_RTCP:
      return 0;
   }
   return 0;
}

/*! \brief Wait, look for hangups and condition arg */
int ast_safe_sleep_conditional(struct ast_channel *chan, int timeout_ms, int (*cond)(void*), void *data)
{
   struct ast_frame *f;
   struct ast_silence_generator *silgen = NULL;
   int res = 0;
   struct timeval start;
   int ms;
   AST_LIST_HEAD_NOLOCK(, ast_frame) deferred_frames;

   AST_LIST_HEAD_INIT_NOLOCK(&deferred_frames);

   /* If no other generator is present, start silencegen while waiting */
   if (ast_opt_transmit_silence && !ast_channel_generatordata(chan)) {
      silgen = ast_channel_start_silence_generator(chan);
   }

   start = ast_tvnow();
   while ((ms = ast_remaining_ms(start, timeout_ms))) {
      struct ast_frame *dup_f = NULL;

      if (cond && ((*cond)(data) == 0)) {
         break;
      }
      ms = ast_waitfor(chan, ms);
      if (ms < 0) {
         res = -1;
         break;
      }
      if (ms > 0) {
         f = ast_read(chan);
         if (!f) {
            res = -1;
            break;
         }

         if (!ast_is_deferrable_frame(f)) {
            ast_frfree(f);
            continue;
         }

         if ((dup_f = ast_frisolate(f))) {
            if (dup_f != f) {
               ast_frfree(f);
            }
            AST_LIST_INSERT_HEAD(&deferred_frames, dup_f, frame_list);
         }
      }
   }

   /* stop silgen if present */
   if (silgen) {
      ast_channel_stop_silence_generator(chan, silgen);
   }

   /* We need to free all the deferred frames, but we only need to
    * queue the deferred frames if there was no error and no
    * hangup was received
    */
   ast_channel_lock(chan);
   while ((f = AST_LIST_REMOVE_HEAD(&deferred_frames, frame_list))) {
      if (!res) {
         ast_queue_frame_head(chan, f);
      }
      ast_frfree(f);
   }
   ast_channel_unlock(chan);

   return res;
}

/*! \brief Wait, look for hangups */
int ast_safe_sleep(struct ast_channel *chan, int ms)
{
   return ast_safe_sleep_conditional(chan, ms, NULL, NULL);
}

struct ast_channel *ast_channel_release(struct ast_channel *chan)
{
   /* Safe, even if already unlinked. */
   ao2_unlink(channels, chan);
   return ast_channel_unref(chan);
}

void ast_party_name_init(struct ast_party_name *init)
{
   init->str = NULL;
   init->char_set = AST_PARTY_CHAR_SET_ISO8859_1;
   init->presentation = AST_PRES_ALLOWED_USER_NUMBER_NOT_SCREENED;
   init->valid = 0;
}

void ast_party_name_copy(struct ast_party_name *dest, const struct ast_party_name *src)
{
   if (dest == src) {
      /* Don't copy to self */
      return;
   }

   ast_free(dest->str);
   dest->str = ast_strdup(src->str);
   dest->char_set = src->char_set;
   dest->presentation = src->presentation;
   dest->valid = src->valid;
}

void ast_party_name_set_init(struct ast_party_name *init, const struct ast_party_name *guide)
{
   init->str = NULL;
   init->char_set = guide->char_set;
   init->presentation = guide->presentation;
   init->valid = guide->valid;
}

void ast_party_name_set(struct ast_party_name *dest, const struct ast_party_name *src)
{
   if (dest == src) {
      /* Don't set to self */
      return;
   }

   if (src->str && src->str != dest->str) {
      ast_free(dest->str);
      dest->str = ast_strdup(src->str);
   }

   dest->char_set = src->char_set;
   dest->presentation = src->presentation;
   dest->valid = src->valid;
}

void ast_party_name_free(struct ast_party_name *doomed)
{
   ast_free(doomed->str);
   doomed->str = NULL;
}

void ast_party_number_init(struct ast_party_number *init)
{
   init->str = NULL;
   init->plan = 0;/* Unknown */
   init->presentation = AST_PRES_ALLOWED_USER_NUMBER_NOT_SCREENED;
   init->valid = 0;
}

void ast_party_number_copy(struct ast_party_number *dest, const struct ast_party_number *src)
{
   if (dest == src) {
      /* Don't copy to self */
      return;
   }

   ast_free(dest->str);
   dest->str = ast_strdup(src->str);
   dest->plan = src->plan;
   dest->presentation = src->presentation;
   dest->valid = src->valid;
}

void ast_party_number_set_init(struct ast_party_number *init, const struct ast_party_number *guide)
{
   init->str = NULL;
   init->plan = guide->plan;
   init->presentation = guide->presentation;
   init->valid = guide->valid;
}

void ast_party_number_set(struct ast_party_number *dest, const struct ast_party_number *src)
{
   if (dest == src) {
      /* Don't set to self */
      return;
   }

   if (src->str && src->str != dest->str) {
      ast_free(dest->str);
      dest->str = ast_strdup(src->str);
   }

   dest->plan = src->plan;
   dest->presentation = src->presentation;
   dest->valid = src->valid;
}

void ast_party_number_free(struct ast_party_number *doomed)
{
   ast_free(doomed->str);
   doomed->str = NULL;
}

void ast_party_subaddress_init(struct ast_party_subaddress *init)
{
   init->str = NULL;
   init->type = 0;
   init->odd_even_indicator = 0;
   init->valid = 0;
}

void ast_party_subaddress_copy(struct ast_party_subaddress *dest, const struct ast_party_subaddress *src)
{
   if (dest == src) {
      /* Don't copy to self */
      return;
   }

   ast_free(dest->str);
   dest->str = ast_strdup(src->str);
   dest->type = src->type;
   dest->odd_even_indicator = src->odd_even_indicator;
   dest->valid = src->valid;
}

void ast_party_subaddress_set_init(struct ast_party_subaddress *init, const struct ast_party_subaddress *guide)
{
   init->str = NULL;
   init->type = guide->type;
   init->odd_even_indicator = guide->odd_even_indicator;
   init->valid = guide->valid;
}

void ast_party_subaddress_set(struct ast_party_subaddress *dest, const struct ast_party_subaddress *src)
{
   if (dest == src) {
      /* Don't set to self */
      return;
   }

   if (src->str && src->str != dest->str) {
      ast_free(dest->str);
      dest->str = ast_strdup(src->str);
   }

   dest->type = src->type;
   dest->odd_even_indicator = src->odd_even_indicator;
   dest->valid = src->valid;
}

void ast_party_subaddress_free(struct ast_party_subaddress *doomed)
{
   ast_free(doomed->str);
   doomed->str = NULL;
}

void ast_set_party_id_all(struct ast_set_party_id *update_id)
{
   update_id->name = 1;
   update_id->number = 1;
   update_id->subaddress = 1;
}

void ast_party_id_init(struct ast_party_id *init)
{
   ast_party_name_init(&init->name);
   ast_party_number_init(&init->number);
   ast_party_subaddress_init(&init->subaddress);
   init->tag = NULL;
}

void ast_party_id_copy(struct ast_party_id *dest, const struct ast_party_id *src)
{
   if (dest == src) {
      /* Don't copy to self */
      return;
   }

   ast_party_name_copy(&dest->name, &src->name);
   ast_party_number_copy(&dest->number, &src->number);
   ast_party_subaddress_copy(&dest->subaddress, &src->subaddress);

   ast_free(dest->tag);
   dest->tag = ast_strdup(src->tag);
}

void ast_party_id_set_init(struct ast_party_id *init, const struct ast_party_id *guide)
{
   ast_party_name_set_init(&init->name, &guide->name);
   ast_party_number_set_init(&init->number, &guide->number);
   ast_party_subaddress_set_init(&init->subaddress, &guide->subaddress);
   init->tag = NULL;
}

void ast_party_id_set(struct ast_party_id *dest, const struct ast_party_id *src, const struct ast_set_party_id *update)
{
   if (dest == src) {
      /* Don't set to self */
      return;
   }

   if (!update || update->name) {
      ast_party_name_set(&dest->name, &src->name);
   }
   if (!update || update->number) {
      ast_party_number_set(&dest->number, &src->number);
   }
   if (!update || update->subaddress) {
      ast_party_subaddress_set(&dest->subaddress, &src->subaddress);
   }

   if (src->tag && src->tag != dest->tag) {
      ast_free(dest->tag);
      dest->tag = ast_strdup(src->tag);
   }
}

void ast_party_id_free(struct ast_party_id *doomed)
{
   ast_party_name_free(&doomed->name);
   ast_party_number_free(&doomed->number);
   ast_party_subaddress_free(&doomed->subaddress);

   ast_free(doomed->tag);
   doomed->tag = NULL;
}

int ast_party_id_presentation(const struct ast_party_id *id)
{
   int number_priority;
   int number_value;
   int number_screening;
   int name_priority;
   int name_value;

   /* Determine name presentation priority. */
   if (!id->name.valid) {
      name_value = AST_PRES_UNAVAILABLE;
      name_priority = 3;
   } else {
      name_value = id->name.presentation & AST_PRES_RESTRICTION;
      switch (name_value) {
      case AST_PRES_RESTRICTED:
         name_priority = 0;
         break;
      case AST_PRES_ALLOWED:
         name_priority = 1;
         break;
      case AST_PRES_UNAVAILABLE:
         name_priority = 2;
         break;
      default:
         name_value = AST_PRES_UNAVAILABLE;
         name_priority = 3;
         break;
      }
   }

   /* Determine number presentation priority. */
   if (!id->number.valid) {
      number_screening = AST_PRES_USER_NUMBER_UNSCREENED;
      number_value = AST_PRES_UNAVAILABLE;
      number_priority = 3;
   } else {
      number_screening = id->number.presentation & AST_PRES_NUMBER_TYPE;
      number_value = id->number.presentation & AST_PRES_RESTRICTION;
      switch (number_value) {
      case AST_PRES_RESTRICTED:
         number_priority = 0;
         break;
      case AST_PRES_ALLOWED:
         number_priority = 1;
         break;
      case AST_PRES_UNAVAILABLE:
         number_priority = 2;
         break;
      default:
         number_screening = AST_PRES_USER_NUMBER_UNSCREENED;
         number_value = AST_PRES_UNAVAILABLE;
         number_priority = 3;
         break;
      }
   }

   /* Select the wining presentation value. */
   if (name_priority < number_priority) {
      number_value = name_value;
   }
   if (number_value == AST_PRES_UNAVAILABLE) {
      return AST_PRES_NUMBER_NOT_AVAILABLE;
   }

   return number_value | number_screening;
}

void ast_party_id_invalidate(struct ast_party_id *id)
{
   id->name.valid = 0;
   id->number.valid = 0;
   id->subaddress.valid = 0;
}

void ast_party_id_reset(struct ast_party_id *id)
{
   ast_party_id_free(id);
   ast_party_id_init(id);
}

struct ast_party_id ast_party_id_merge(struct ast_party_id *base, struct ast_party_id *overlay)
{
   struct ast_party_id merged;

   merged = *base;
   if (overlay->name.valid) {
      merged.name = overlay->name;
   }
   if (overlay->number.valid) {
      merged.number = overlay->number;
   }
   if (overlay->subaddress.valid) {
      merged.subaddress = overlay->subaddress;
   }
   /* Note the actual structure is returned and not a pointer to it! */
   return merged;
}

void ast_party_id_merge_copy(struct ast_party_id *dest, struct ast_party_id *base, struct ast_party_id *overlay)
{
   struct ast_party_id merged;

   merged = ast_party_id_merge(base, overlay);
   ast_party_id_copy(dest, &merged);
}

void ast_party_dialed_init(struct ast_party_dialed *init)
{
   init->number.str = NULL;
   init->number.plan = 0;/* Unknown */
   ast_party_subaddress_init(&init->subaddress);
   init->transit_network_select = 0;
}

void ast_party_dialed_copy(struct ast_party_dialed *dest, const struct ast_party_dialed *src)
{
   if (dest == src) {
      /* Don't copy to self */
      return;
   }

   ast_free(dest->number.str);
   dest->number.str = ast_strdup(src->number.str);
   dest->number.plan = src->number.plan;
   ast_party_subaddress_copy(&dest->subaddress, &src->subaddress);
   dest->transit_network_select = src->transit_network_select;
}

void ast_party_dialed_set_init(struct ast_party_dialed *init, const struct ast_party_dialed *guide)
{
   init->number.str = NULL;
   init->number.plan = guide->number.plan;
   ast_party_subaddress_set_init(&init->subaddress, &guide->subaddress);
   init->transit_network_select = guide->transit_network_select;
}

void ast_party_dialed_set(struct ast_party_dialed *dest, const struct ast_party_dialed *src)
{
   if (src->number.str && src->number.str != dest->number.str) {
      ast_free(dest->number.str);
      dest->number.str = ast_strdup(src->number.str);
   }
   dest->number.plan = src->number.plan;

   ast_party_subaddress_set(&dest->subaddress, &src->subaddress);

   dest->transit_network_select = src->transit_network_select;
}

void ast_party_dialed_free(struct ast_party_dialed *doomed)
{
   ast_free(doomed->number.str);
   doomed->number.str = NULL;
   ast_party_subaddress_free(&doomed->subaddress);
}

void ast_party_caller_init(struct ast_party_caller *init)
{
   ast_party_id_init(&init->id);
   ast_party_id_init(&init->ani);
   ast_party_id_init(&init->priv);
   init->ani2 = 0;
}

void ast_party_caller_copy(struct ast_party_caller *dest, const struct ast_party_caller *src)
{
   if (dest == src) {
      /* Don't copy to self */
      return;
   }

   ast_party_id_copy(&dest->id, &src->id);
   ast_party_id_copy(&dest->ani, &src->ani);
   ast_party_id_copy(&dest->priv, &src->priv);
   dest->ani2 = src->ani2;
}

void ast_party_caller_set_init(struct ast_party_caller *init, const struct ast_party_caller *guide)
{
   ast_party_id_set_init(&init->id, &guide->id);
   ast_party_id_set_init(&init->ani, &guide->ani);
   ast_party_id_set_init(&init->priv, &guide->priv);
   init->ani2 = guide->ani2;
}

void ast_party_caller_set(struct ast_party_caller *dest, const struct ast_party_caller *src, const struct ast_set_party_caller *update)
{
   ast_party_id_set(&dest->id, &src->id, update ? &update->id : NULL);
   ast_party_id_set(&dest->ani, &src->ani, update ? &update->ani : NULL);
   ast_party_id_set(&dest->priv, &src->priv, update ? &update->priv : NULL);
   dest->ani2 = src->ani2;
}

void ast_party_caller_free(struct ast_party_caller *doomed)
{
   ast_party_id_free(&doomed->id);
   ast_party_id_free(&doomed->ani);
   ast_party_id_free(&doomed->priv);
}

void ast_party_connected_line_init(struct ast_party_connected_line *init)
{
   ast_party_id_init(&init->id);
   ast_party_id_init(&init->ani);
   ast_party_id_init(&init->priv);
   init->ani2 = 0;
   init->source = AST_CONNECTED_LINE_UPDATE_SOURCE_UNKNOWN;
}

void ast_party_connected_line_copy(struct ast_party_connected_line *dest, const struct ast_party_connected_line *src)
{
   if (dest == src) {
      /* Don't copy to self */
      return;
   }

   ast_party_id_copy(&dest->id, &src->id);
   ast_party_id_copy(&dest->ani, &src->ani);
   ast_party_id_copy(&dest->priv, &src->priv);
   dest->ani2 = src->ani2;
   dest->source = src->source;
}

void ast_party_connected_line_set_init(struct ast_party_connected_line *init, const struct ast_party_connected_line *guide)
{
   ast_party_id_set_init(&init->id, &guide->id);
   ast_party_id_set_init(&init->ani, &guide->ani);
   ast_party_id_set_init(&init->priv, &guide->priv);
   init->ani2 = guide->ani2;
   init->source = guide->source;
}

void ast_party_connected_line_set(struct ast_party_connected_line *dest, const struct ast_party_connected_line *src, const struct ast_set_party_connected_line *update)
{
   ast_party_id_set(&dest->id, &src->id, update ? &update->id : NULL);
   ast_party_id_set(&dest->ani, &src->ani, update ? &update->ani : NULL);
   ast_party_id_set(&dest->priv, &src->priv, update ? &update->priv : NULL);
   dest->ani2 = src->ani2;
   dest->source = src->source;
}

void ast_party_connected_line_collect_caller(struct ast_party_connected_line *connected, struct ast_party_caller *caller)
{
   connected->id = caller->id;
   connected->ani = caller->ani;
   connected->priv = caller->priv;
   connected->ani2 = caller->ani2;
   connected->source = AST_CONNECTED_LINE_UPDATE_SOURCE_UNKNOWN;
}

void ast_party_connected_line_free(struct ast_party_connected_line *doomed)
{
   ast_party_id_free(&doomed->id);
   ast_party_id_free(&doomed->ani);
   ast_party_id_free(&doomed->priv);
}

void ast_party_redirecting_reason_init(struct ast_party_redirecting_reason *init)
{
   init->str = NULL;
   init->code = AST_REDIRECTING_REASON_UNKNOWN;
}

void ast_party_redirecting_reason_copy(struct ast_party_redirecting_reason *dest, const struct ast_party_redirecting_reason *src)
{
   if (dest == src) {
      return;
   }

   ast_free(dest->str);
   dest->str = ast_strdup(src->str);
   dest->code = src->code;
}

void ast_party_redirecting_reason_set_init(struct ast_party_redirecting_reason *init, const struct ast_party_redirecting_reason *guide)
{
   init->str = NULL;
   init->code = guide->code;
}

void ast_party_redirecting_reason_set(struct ast_party_redirecting_reason *dest, const struct ast_party_redirecting_reason *src)
{
   if (dest == src) {
      return;
   }

   if (src->str && src->str != dest->str) {
      ast_free(dest->str);
      dest->str = ast_strdup(src->str);
   }

   dest->code = src->code;
}

void ast_party_redirecting_reason_free(struct ast_party_redirecting_reason *doomed)
{
   ast_free(doomed->str);
}


void ast_party_redirecting_init(struct ast_party_redirecting *init)
{
   ast_party_id_init(&init->orig);
   ast_party_id_init(&init->from);
   ast_party_id_init(&init->to);
   ast_party_id_init(&init->priv_orig);
   ast_party_id_init(&init->priv_from);
   ast_party_id_init(&init->priv_to);
   ast_party_redirecting_reason_init(&init->reason);
   ast_party_redirecting_reason_init(&init->orig_reason);
   init->count = 0;
}

void ast_party_redirecting_copy(struct ast_party_redirecting *dest, const struct ast_party_redirecting *src)
{
   if (dest == src) {
      /* Don't copy to self */
      return;
   }

   ast_party_id_copy(&dest->orig, &src->orig);
   ast_party_id_copy(&dest->from, &src->from);
   ast_party_id_copy(&dest->to, &src->to);
   ast_party_id_copy(&dest->priv_orig, &src->priv_orig);
   ast_party_id_copy(&dest->priv_from, &src->priv_from);
   ast_party_id_copy(&dest->priv_to, &src->priv_to);
   ast_party_redirecting_reason_copy(&dest->reason, &src->reason);
   ast_party_redirecting_reason_copy(&dest->orig_reason, &src->orig_reason);
   dest->count = src->count;
}

void ast_party_redirecting_set_init(struct ast_party_redirecting *init, const struct ast_party_redirecting *guide)
{
   ast_party_id_set_init(&init->orig, &guide->orig);
   ast_party_id_set_init(&init->from, &guide->from);
   ast_party_id_set_init(&init->to, &guide->to);
   ast_party_id_set_init(&init->priv_orig, &guide->priv_orig);
   ast_party_id_set_init(&init->priv_from, &guide->priv_from);
   ast_party_id_set_init(&init->priv_to, &guide->priv_to);
   ast_party_redirecting_reason_set_init(&init->reason, &guide->reason);
   ast_party_redirecting_reason_set_init(&init->orig_reason, &guide->orig_reason);
   init->count = guide->count;
}

void ast_party_redirecting_set(struct ast_party_redirecting *dest, const struct ast_party_redirecting *src, const struct ast_set_party_redirecting *update)
{
   ast_party_id_set(&dest->orig, &src->orig, update ? &update->orig : NULL);
   ast_party_id_set(&dest->from, &src->from, update ? &update->from : NULL);
   ast_party_id_set(&dest->to, &src->to, update ? &update->to : NULL);
   ast_party_id_set(&dest->priv_orig, &src->priv_orig, update ? &update->priv_orig : NULL);
   ast_party_id_set(&dest->priv_from, &src->priv_from, update ? &update->priv_from : NULL);
   ast_party_id_set(&dest->priv_to, &src->priv_to, update ? &update->priv_to : NULL);
   ast_party_redirecting_reason_set(&dest->reason, &src->reason);
   ast_party_redirecting_reason_set(&dest->orig_reason, &src->orig_reason);
   dest->count = src->count;
}

void ast_party_redirecting_free(struct ast_party_redirecting *doomed)
{
   ast_party_id_free(&doomed->orig);
   ast_party_id_free(&doomed->from);
   ast_party_id_free(&doomed->to);
   ast_party_id_free(&doomed->priv_orig);
   ast_party_id_free(&doomed->priv_from);
   ast_party_id_free(&doomed->priv_to);
   ast_party_redirecting_reason_free(&doomed->reason);
   ast_party_redirecting_reason_free(&doomed->orig_reason);
}

/*! \brief Free a channel structure */
static void ast_channel_destructor(void *obj)
{
   struct ast_channel *chan = obj;
   struct ast_var_t *vardata;
   struct ast_frame *f;
   struct varshead *headp;
   struct ast_datastore *datastore;
   char device_name[AST_CHANNEL_NAME];
   ast_callid callid;

   ast_debug(1, "Channel %p '%s' destroying\n", chan, ast_channel_name(chan));

   /* Stop monitoring */
   if (ast_channel_monitor(chan)) {
      ast_channel_monitor(chan)->stop(chan, 0);
   }

   /* If there is native format music-on-hold state, free it */
   if (ast_channel_music_state(chan)) {
      ast_moh_cleanup(chan);
   }

   ast_pbx_hangup_handler_destroy(chan);

   /* Things that may possibly raise Stasis messages shouldn't occur after this point */
   ast_set_flag(ast_channel_flags(chan), AST_FLAG_DEAD);

   if (ast_channel_internal_is_finalized(chan)) {
      /* A channel snapshot should not be in the process of being staged now. */
      ast_assert(!ast_test_flag(ast_channel_flags(chan), AST_FLAG_SNAPSHOT_STAGE));

      ast_channel_lock(chan);
      ast_channel_publish_final_snapshot(chan);
      ast_channel_unlock(chan);
   }

   ast_channel_lock(chan);

   /* Get rid of each of the data stores on the channel */
   while ((datastore = AST_LIST_REMOVE_HEAD(ast_channel_datastores(chan), entry)))
      /* Free the data store */
      ast_datastore_free(datastore);

   /* While the channel is locked, take the reference to its callid while we tear down the call. */
   callid = ast_channel_callid(chan);
   ast_channel_callid_cleanup(chan);

   ast_channel_unlock(chan);

   /* Lock and unlock the channel just to be sure nobody has it locked still
      due to a reference that was stored in a datastore. (i.e. app_chanspy) */
   ast_channel_lock(chan);
   ast_channel_unlock(chan);

   if (ast_channel_tech_pvt(chan)) {
      ast_log_callid(LOG_WARNING, callid, "Channel '%s' may not have been hung up properly\n", ast_channel_name(chan));
      ast_free(ast_channel_tech_pvt(chan));
   }

   if (ast_channel_sched(chan)) {
      ast_sched_context_destroy(ast_channel_sched(chan));
   }

   if (ast_channel_internal_is_finalized(chan)) {
      char *dashptr;

      ast_copy_string(device_name, ast_channel_name(chan), sizeof(device_name));
      if ((dashptr = strrchr(device_name, '-'))) {
         *dashptr = '\0';
      }
   } else {
      device_name[0] = '\0';
   }

   /* Free translators */
   if (ast_channel_readtrans(chan))
      ast_translator_free_path(ast_channel_readtrans(chan));
   if (ast_channel_writetrans(chan))
      ast_translator_free_path(ast_channel_writetrans(chan));
   if (ast_channel_pbx(chan))
      ast_log_callid(LOG_WARNING, callid, "PBX may not have been terminated properly on '%s'\n", ast_channel_name(chan));

   /* Free formats */
   ast_channel_set_oldwriteformat(chan, NULL);
   ast_channel_set_rawreadformat(chan, NULL);
   ast_channel_set_rawwriteformat(chan, NULL);
   ast_channel_set_readformat(chan, NULL);
   ast_channel_set_writeformat(chan, NULL);

   ast_party_dialed_free(ast_channel_dialed(chan));
   ast_party_caller_free(ast_channel_caller(chan));
   ast_party_connected_line_free(ast_channel_connected(chan));
   ast_party_connected_line_free(ast_channel_connected_indicated(chan));
   ast_party_redirecting_free(ast_channel_redirecting(chan));

   /* Close pipes if appropriate */
   ast_channel_internal_alertpipe_close(chan);
   if (ast_channel_timer(chan)) {
      ast_timer_close(ast_channel_timer(chan));
      ast_channel_timer_set(chan, NULL);
   }
   while ((f = AST_LIST_REMOVE_HEAD(ast_channel_readq(chan), frame_list)))
      ast_frfree(f);

   /* loop over the variables list, freeing all data and deleting list items */
   /* no need to lock the list, as the channel is already locked */
   headp = ast_channel_varshead(chan);
   while ((vardata = AST_LIST_REMOVE_HEAD(headp, entries)))
      ast_var_delete(vardata);

   ast_app_group_discard(chan);

   /* Destroy the jitterbuffer */
   ast_jb_destroy(chan);

   if (ast_channel_cdr(chan)) {
      ast_cdr_free(ast_channel_cdr(chan));
      ast_channel_cdr_set(chan, NULL);
   }

   if (ast_channel_zone(chan)) {
      ast_channel_zone_set(chan, ast_tone_zone_unref(ast_channel_zone(chan)));
   }

   ast_channel_internal_cleanup(chan);

   if (device_name[0]) {
      /*
       * We have a device name to notify of a new state.
       *
       * Queue an unknown state, because, while we know that this particular
       * instance is dead, we don't know the state of all other possible
       * instances.
       */
      ast_devstate_changed_literal(AST_DEVICE_UNKNOWN, (ast_test_flag(ast_channel_flags(chan), AST_FLAG_DISABLE_DEVSTATE_CACHE) ? AST_DEVSTATE_NOT_CACHABLE : AST_DEVSTATE_CACHABLE), device_name);
   }

   ast_channel_nativeformats_set(chan, NULL);

   ast_channel_named_callgroups_set(chan, NULL);
   ast_channel_named_pickupgroups_set(chan, NULL);

   ast_atomic_fetchadd_int(&chancount, -1);
}

/*! \brief Free a dummy channel structure */
static void ast_dummy_channel_destructor(void *obj)
{
   struct ast_channel *chan = obj;
   struct ast_datastore *datastore;
   struct ast_var_t *vardata;
   struct varshead *headp;

   ast_pbx_hangup_handler_destroy(chan);

   /* Get rid of each of the data stores on the channel */
   while ((datastore = AST_LIST_REMOVE_HEAD(ast_channel_datastores(chan), entry))) {
      /* Free the data store */
      ast_datastore_free(datastore);
   }

   ast_party_dialed_free(ast_channel_dialed(chan));
   ast_party_caller_free(ast_channel_caller(chan));
   ast_party_connected_line_free(ast_channel_connected(chan));
   ast_party_connected_line_free(ast_channel_connected_indicated(chan));
   ast_party_redirecting_free(ast_channel_redirecting(chan));

   /* loop over the variables list, freeing all data and deleting list items */
   /* no need to lock the list, as the channel is already locked */
   headp = ast_channel_varshead(chan);
   while ((vardata = AST_LIST_REMOVE_HEAD(headp, entries)))
      ast_var_delete(vardata);

   if (ast_channel_cdr(chan)) {
      ast_cdr_free(ast_channel_cdr(chan));
      ast_channel_cdr_set(chan, NULL);
   }

   ast_channel_internal_cleanup(chan);
}

int ast_channel_datastore_inherit(struct ast_channel *from, struct ast_channel *to)
{
   struct ast_datastore *datastore = NULL, *datastore2;

   AST_LIST_TRAVERSE(ast_channel_datastores(from), datastore, entry) {
      if (datastore->inheritance > 0) {
         datastore2 = ast_datastore_alloc(datastore->info, datastore->uid);
         if (datastore2) {
            datastore2->data = datastore->info->duplicate ? datastore->info->duplicate(datastore->data) : NULL;
            datastore2->inheritance = datastore->inheritance == DATASTORE_INHERIT_FOREVER ? DATASTORE_INHERIT_FOREVER : datastore->inheritance - 1;
            AST_LIST_INSERT_TAIL(ast_channel_datastores(to), datastore2, entry);
         }
      }
   }
   return 0;
}

int ast_channel_datastore_add(struct ast_channel *chan, struct ast_datastore *datastore)
{
   int res = 0;

   AST_LIST_INSERT_HEAD(ast_channel_datastores(chan), datastore, entry);

   return res;
}

int ast_channel_datastore_remove(struct ast_channel *chan, struct ast_datastore *datastore)
{
   return AST_LIST_REMOVE(ast_channel_datastores(chan), datastore, entry) ? 0 : -1;
}

struct ast_datastore *ast_channel_datastore_find(struct ast_channel *chan, const struct ast_datastore_info *info, const char *uid)
{
   struct ast_datastore *datastore = NULL;

   if (info == NULL)
      return NULL;

   AST_LIST_TRAVERSE(ast_channel_datastores(chan), datastore, entry) {
      if (datastore->info != info) {
         continue;
      }

      if (uid == NULL) {
         /* matched by type only */
         break;
      }

      if ((datastore->uid != NULL) && !strcasecmp(uid, datastore->uid)) {
         /* Matched by type AND uid */
         break;
      }
   }

   return datastore;
}

/*! Set the file descriptor on the channel */
void ast_channel_set_fd(struct ast_channel *chan, int which, int fd)
{
   ast_channel_internal_fd_set(chan, which, fd);
   return;
}

void ast_channel_clear_softhangup(struct ast_channel *chan, int flag)
{
   ast_channel_lock(chan);

   ast_channel_softhangup_internal_flag_clear(chan, flag);

   if (!ast_channel_softhangup_internal_flag(chan)) {
      struct ast_frame *fr;

      /* If we have completely cleared the softhangup flag,
       * then we need to fully abort the hangup process.  This requires
       * pulling the END_OF_Q frame out of the channel frame queue if it
       * still happens to be there. */

      fr = AST_LIST_LAST(ast_channel_readq(chan));
      if (fr && fr->frametype == AST_FRAME_CONTROL &&
            fr->subclass.integer == AST_CONTROL_END_OF_Q) {
         AST_LIST_REMOVE(ast_channel_readq(chan), fr, frame_list);
         ast_frfree(fr);
      }
   }

   ast_channel_unlock(chan);
}

/*! \brief Softly hangup a channel, don't lock */
int ast_softhangup_nolock(struct ast_channel *chan, int cause)
{
   ast_debug(1, "Soft-Hanging (%#04x) up channel '%s'\n", (unsigned)cause, ast_channel_name(chan));
   /* Inform channel driver that we need to be hung up, if it cares */
   ast_channel_softhangup_internal_flag_add(chan, cause);
   ast_queue_frame(chan, &ast_null_frame);
   /* Interrupt any poll call or such */
   if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_BLOCKING))
      pthread_kill(ast_channel_blocker(chan), SIGURG);
   return 0;
}

/*! \brief Softly hangup a channel, lock */
int ast_softhangup(struct ast_channel *chan, int cause)
{
   RAII_VAR(struct ast_json *, blob, NULL, ast_json_unref);
   int res;

   ast_channel_lock(chan);
   res = ast_softhangup_nolock(chan, cause);
   blob = ast_json_pack("{s: i, s: b}",
              "cause", cause,
              "soft", 1);
   ast_channel_publish_blob(chan, ast_channel_hangup_request_type(), blob);
   ast_channel_unlock(chan);

   return res;
}

static void free_translation(struct ast_channel *clonechan)
{
   if (ast_channel_writetrans(clonechan)) {
      ast_translator_free_path(ast_channel_writetrans(clonechan));
   }
   if (ast_channel_readtrans(clonechan)) {
      ast_translator_free_path(ast_channel_readtrans(clonechan));
   }
   ast_channel_writetrans_set(clonechan, NULL);
   ast_channel_readtrans_set(clonechan, NULL);
}

void ast_set_hangupsource(struct ast_channel *chan, const char *source, int force)
{
   RAII_VAR(struct ast_channel *, bridge, ast_channel_bridge_peer(chan), ast_channel_cleanup);

   ast_channel_lock(chan);
   if (force || ast_strlen_zero(ast_channel_hangupsource(chan))) {
      ast_channel_hangupsource_set(chan, source);
   }
   ast_channel_unlock(chan);

   if (bridge) {
      ast_channel_lock(bridge);
      if (force || ast_strlen_zero(ast_channel_hangupsource(bridge))) {
         ast_channel_hangupsource_set(bridge, source);
      }
      ast_channel_unlock(bridge);
   }
}

int ast_channel_has_audio_frame_or_monitor(struct ast_channel *chan)
{
   return ast_channel_monitor(chan)
      || !ast_audiohook_write_list_empty(ast_channel_audiohooks(chan))
      || !ast_framehook_list_contains_no_active(ast_channel_framehooks(chan));
}

int ast_channel_has_hook_requiring_audio(struct ast_channel *chan)
{
   return ast_channel_monitor(chan)
      || !ast_audiohook_write_list_empty(ast_channel_audiohooks(chan))
      || !ast_framehook_list_contains_no_active_of_type(ast_channel_framehooks(chan), AST_FRAME_VOICE);
}

static void destroy_hooks(struct ast_channel *chan)
{
   if (ast_channel_audiohooks(chan)) {
      ast_audiohook_detach_list(ast_channel_audiohooks(chan));
      ast_channel_audiohooks_set(chan, NULL);
   }

   ast_framehook_list_destroy(chan);
}

/*! \brief Hangup a channel */
void ast_hangup(struct ast_channel *chan)
{
   /* Be NULL safe for RAII_VAR() usage. */
   if (!chan) {
      return;
   }

   ast_debug(1, "Channel %p '%s' hanging up.  Refs: %d\n", chan, ast_channel_name(chan),
      ao2_ref(chan, 0));

   ast_autoservice_stop(chan);

   ast_channel_lock(chan);

   while (ast_channel_masq(chan) || ast_channel_masqr(chan))  {
      CHANNEL_DEADLOCK_AVOIDANCE(chan);
   }

   /* Mark as a zombie so a masquerade cannot be setup on this channel. */
   ast_set_flag(ast_channel_flags(chan), AST_FLAG_ZOMBIE);

   ast_channel_unlock(chan);

   /*
    * XXX if running the hangup handlers here causes problems
    * because the handlers take too long to execute, we could move
    * the meat of this function into another thread.  A thread
    * where channels go to die.
    *
    * If this is done, ast_autoservice_chan_hangup_peer() will no
    * longer be needed.
    */
   ast_pbx_hangup_handler_run(chan);
   ao2_unlink(channels, chan);
   ast_channel_lock(chan);

   destroy_hooks(chan);

   free_translation(chan);
   /* Close audio stream */
   if (ast_channel_stream(chan)) {
      ast_closestream(ast_channel_stream(chan));
      ast_channel_stream_set(chan, NULL);
   }
   /* Close video stream */
   if (ast_channel_vstream(chan)) {
      ast_closestream(ast_channel_vstream(chan));
      ast_channel_vstream_set(chan, NULL);
   }
   if (ast_channel_sched(chan)) {
      ast_sched_context_destroy(ast_channel_sched(chan));
      ast_channel_sched_set(chan, NULL);
   }

   if (ast_channel_generatordata(chan)) { /* Clear any tone stuff remaining */
      if (ast_channel_generator(chan) && ast_channel_generator(chan)->release) {
         ast_channel_generator(chan)->release(chan, ast_channel_generatordata(chan));
      }
   }
   ast_channel_generatordata_set(chan, NULL);
   ast_channel_generator_set(chan, NULL);

   if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_BLOCKING)) {
      ast_log(LOG_WARNING, "Hard hangup called by thread LWP %d on %s, while blocked by thread LWP %d in procedure %s!  Expect a failure\n",
         ast_get_tid(), ast_channel_name(chan), ast_channel_blocker_tid(chan),
         ast_channel_blockproc(chan));
      ast_assert(0);
   }

   if (ast_channel_tech(chan)->hangup) {
      ast_channel_tech(chan)->hangup(chan);
   }

   ast_channel_unlock(chan);

   ast_cc_offer(chan);

   ast_channel_unref(chan);
}

/*!
 * \internal
 * \brief Set channel answered time if not already set.
 * \since 13.11.0
 *
 * \param chan Channel to set answered time.
 *
 * \return Nothing
 */
static void set_channel_answer_time(struct ast_channel *chan)
{
   if (ast_tvzero(ast_channel_answertime(chan))) {
      struct timeval answertime;

      answertime = ast_tvnow();
      ast_channel_answertime_set(chan, &answertime);
   }
}


int ast_raw_answer_with_stream_topology(struct ast_channel *chan, struct ast_stream_topology *topology)
{
   int res = 0;
   SCOPE_TRACE(1, "%s\n", ast_channel_name(chan));

   ast_channel_lock(chan);

   /* You can't answer an outbound call */
   if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_OUTGOING)) {
      ast_channel_unlock(chan);
      return 0;
   }

   /* Stop if we're a zombie or need a soft hangup */
   if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_ZOMBIE) || ast_check_hangup(chan)) {
      ast_channel_unlock(chan);
      return -1;
   }

   /*
    * Mark when incoming channel answered so we can know how
    * long the channel has been up.
    */
   set_channel_answer_time(chan);

   ast_channel_unlock(chan);

   switch (ast_channel_state(chan)) {
   case AST_STATE_RINGING:
   case AST_STATE_RING:
      ast_channel_lock(chan);
      if (ast_channel_tech(chan)->answer_with_stream_topology) {
         res = ast_channel_tech(chan)->answer_with_stream_topology(chan, topology);

      } else if (ast_channel_tech(chan)->answer) {
         res = ast_channel_tech(chan)->answer(chan);
      }
      ast_setstate(chan, AST_STATE_UP);
      ast_channel_unlock(chan);
      break;
   case AST_STATE_UP:
      break;
   default:
      break;
   }

   ast_indicate(chan, -1);

   return res;
}

int ast_raw_answer(struct ast_channel *chan)
{
   return ast_raw_answer_with_stream_topology(chan, NULL);
}

int __ast_answer(struct ast_channel *chan, unsigned int delay)
{
   int res = 0;
   enum ast_channel_state old_state;
   SCOPE_TRACE(1, "%s\n", ast_channel_name(chan));

   old_state = ast_channel_state(chan);
   if ((res = ast_raw_answer(chan))) {
      return res;
   }

   switch (old_state) {
   case AST_STATE_RINGING:
   case AST_STATE_RING:
      /* wait for media to start flowing, but don't wait any longer
       * than 'delay' or 500 milliseconds, whichever is longer
       */
      do {
         AST_LIST_HEAD_NOLOCK(, ast_frame) frames;
         struct ast_frame *cur;
         struct ast_frame *new_frame;
         int timeout_ms = MAX(delay, 500);
         unsigned int done = 0;
         struct timeval start;

         AST_LIST_HEAD_INIT_NOLOCK(&frames);

         start = ast_tvnow();
         for (;;) {
            int ms = ast_remaining_ms(start, timeout_ms);
            ms = ast_waitfor(chan, ms);
            if (ms < 0) {
               ast_log(LOG_WARNING, "Error condition occurred when polling channel %s for a voice frame: %s\n", ast_channel_name(chan), strerror(errno));
               res = -1;
               break;
            }
            if (ms == 0) {
               ast_debug(2, "Didn't receive a media frame from %s within %u ms of answering. Continuing anyway\n", ast_channel_name(chan), MAX(delay, 500));
               break;
            }
            cur = ast_read(chan);
            if (!cur || ((cur->frametype == AST_FRAME_CONTROL) &&
                    (cur->subclass.integer == AST_CONTROL_HANGUP))) {
               if (cur) {
                  ast_frfree(cur);
               }
               res = -1;
               ast_debug(2, "Hangup of channel %s detected in answer routine\n", ast_channel_name(chan));
               break;
            }

            if ((new_frame = ast_frisolate(cur)) != cur) {
               ast_frfree(cur);
            }

            AST_LIST_INSERT_HEAD(&frames, new_frame, frame_list);

            /* if a specific delay period was requested, continue
             * until that delay has passed. don't stop just because
             * incoming media has arrived.
             */
            if (delay) {
               continue;
            }

            switch (new_frame->frametype) {
               /* all of these frametypes qualify as 'media' */
            case AST_FRAME_VOICE:
            case AST_FRAME_VIDEO:
            case AST_FRAME_TEXT:
            case AST_FRAME_TEXT_DATA:
            case AST_FRAME_DTMF_BEGIN:
            case AST_FRAME_DTMF_END:
            case AST_FRAME_IMAGE:
            case AST_FRAME_HTML:
            case AST_FRAME_MODEM:
            case AST_FRAME_RTCP:
               done = 1;
               break;
            case AST_FRAME_CONTROL:
            case AST_FRAME_IAX:
            case AST_FRAME_BRIDGE_ACTION:
            case AST_FRAME_BRIDGE_ACTION_SYNC:
            case AST_FRAME_NULL:
            case AST_FRAME_CNG:
               break;
            }

            if (done) {
               break;
            }
         }

         ast_channel_lock(chan);
         while ((cur = AST_LIST_REMOVE_HEAD(&frames, frame_list))) {
            if (res == 0) {
               ast_queue_frame_head(chan, cur);
            }
            ast_frfree(cur);
         }
         ast_channel_unlock(chan);
      } while (0);
      break;
   default:
      break;
   }

   return res;
}

int ast_answer(struct ast_channel *chan)
{
   SCOPE_TRACE(1, "%s\n", ast_channel_name(chan));
   return __ast_answer(chan, 0);
}

inline int ast_auto_answer(struct ast_channel *chan)
{
   if (ast_channel_state(chan) == AST_STATE_UP) {
      /* Already answered */
      return 0;
   }
   return ast_answer(chan);
}

int64_t ast_channel_get_duration_ms(struct ast_channel *chan)
{
   ast_assert(NULL != chan);

   if (ast_tvzero(ast_channel_creationtime(chan))) {
      return 0;
   }
   return ast_tvdiff_ms(ast_tvnow(), ast_channel_creationtime(chan));
}

int ast_channel_get_duration(struct ast_channel *chan)
{
   return (ast_channel_get_duration_ms(chan) / 1000);
}

int64_t ast_channel_get_up_time_ms(struct ast_channel *chan)
{
   ast_assert(NULL != chan);

   if (ast_tvzero(ast_channel_answertime(chan))) {
      return 0;
   }
   return ast_tvdiff_ms(ast_tvnow(), ast_channel_answertime(chan));
}

int ast_channel_get_up_time(struct ast_channel *chan)
{
   return (ast_channel_get_up_time_ms(chan) / 1000);
}

/*!
 * \brief Determine whether or not we have to trigger dtmf emulating using 50 fps timer events
 * especially when no voice frames are received during dtmf processing (direct media or muted
 * sender case using SIP INFO)
 */
static inline int should_trigger_dtmf_emulating(struct ast_channel *chan)
{
   if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_DEFER_DTMF | AST_FLAG_EMULATE_DTMF)) {
      /* We're in the middle of emulating a digit, or DTMF has been
       * explicitly deferred. Trigger dtmf with periodic 50 pfs timer events, then. */
      return 1;
   }

   if (!ast_tvzero(*ast_channel_dtmf_tv(chan)) &&
         ast_tvdiff_ms(ast_tvnow(), *ast_channel_dtmf_tv(chan)) < 2*AST_MIN_DTMF_GAP) {
      /*
       * We're not in the middle of a digit, but it hasn't been long enough
       * since the last digit, so we'll have to trigger DTMF furtheron.
       * Using 2 times AST_MIN_DTMF_GAP to trigger readq reading for possible
       * buffered next dtmf event
       */
      return 1;
   }

   return 0;
}

static void deactivate_generator_nolock(struct ast_channel *chan)
{
   if (ast_channel_generatordata(chan)) {
      struct ast_generator *generator = ast_channel_generator(chan);

      if (generator && generator->release) {
         generator->release(chan, ast_channel_generatordata(chan));
      }
      ast_channel_generatordata_set(chan, NULL);
      ast_channel_generator_set(chan, NULL);
      ast_channel_set_fd(chan, AST_GENERATOR_FD, -1);
      ast_clear_flag(ast_channel_flags(chan), AST_FLAG_WRITE_INT);
      ast_settimeout(chan, 0, NULL, NULL);
   }
}

void ast_deactivate_generator(struct ast_channel *chan)
{
   ast_channel_lock(chan);
   deactivate_generator_nolock(chan);
   if (should_trigger_dtmf_emulating(chan)) {
      /* if in the middle of dtmf emulation keep 50 tick per sec timer on rolling */
      ast_timer_set_rate(ast_channel_timer(chan), 50);
   }
   ast_channel_unlock(chan);
}

static void generator_write_format_change(struct ast_channel *chan)
{
   struct ast_generator *generator;

   ast_channel_lock(chan);
   generator = ast_channel_generator(chan);
   if (generator && generator->write_format_change) {
      generator->write_format_change(chan, ast_channel_generatordata(chan));
   }
   ast_channel_unlock(chan);
}

static int generator_force(const void *data)
{
   /* Called if generator doesn't have data */
   void *tmp;
   int res;
   int (*generate)(struct ast_channel *chan, void *tmp, int datalen, int samples) = NULL;
   struct ast_channel *chan = (struct ast_channel *)data;

   ast_channel_lock(chan);
   tmp = ast_channel_generatordata(chan);
   ast_channel_generatordata_set(chan, NULL);
   if (ast_channel_generator(chan))
      generate = ast_channel_generator(chan)->generate;
   ast_channel_unlock(chan);

   if (!tmp || !generate) {
      return 0;
   }

   res = generate(chan, tmp, 0, ast_format_get_sample_rate(ast_channel_writeformat(chan)) / 50);

   ast_channel_lock(chan);
   if (ast_channel_generator(chan) && generate == ast_channel_generator(chan)->generate) {
      ast_channel_generatordata_set(chan, tmp);
   }
   ast_channel_unlock(chan);

   if (res) {
      ast_debug(1, "Auto-deactivating generator\n");
      ast_deactivate_generator(chan);
   }

   return 0;
}

int ast_activate_generator(struct ast_channel *chan, struct ast_generator *gen, void *params)
{
   int res = 0;
   void *generatordata = NULL;

   ast_channel_lock(chan);
   if (ast_channel_generatordata(chan)) {
      struct ast_generator *generator_old = ast_channel_generator(chan);

      if (generator_old && generator_old->release) {
         generator_old->release(chan, ast_channel_generatordata(chan));
      }
   }
   if (gen->alloc && !(generatordata = gen->alloc(chan, params))) {
      res = -1;
   }
   ast_channel_generatordata_set(chan, generatordata);
   if (!res) {
      ast_settimeout(chan, 50, generator_force, chan);
      ast_channel_generator_set(chan, gen);
   }
   ast_channel_unlock(chan);

   ast_prod(chan);

   return res;
}

/*! \brief Wait for x amount of time on a file descriptor to have input.  */
int ast_waitfor_n_fd(int *fds, int n, int *ms, int *exception)
{
   int winner = -1;
   ast_waitfor_nandfds(NULL, 0, fds, n, exception, &winner, ms);
   return winner;
}

/*! \brief Wait for x amount of time on a file descriptor to have input.  */
struct ast_channel *ast_waitfor_nandfds(struct ast_channel **c, int n, int *fds, int nfds,
               int *exception, int *outfd, int *ms)
{
   struct timeval start = { 0 , 0 };
   struct pollfd *pfds = NULL;
   int res;
   long rms;
   int x, y, max;
   int sz = nfds;
   struct timeval now = { 0, 0 };
   struct timeval whentohangup = { 0, 0 }, diff;
   struct ast_channel *winner = NULL;
   struct fdmap {
      int chan;
      int fdno;
   } *fdmap = NULL;

   if (outfd) {
      *outfd = -99999;
   }
   if (exception) {
      *exception = 0;
   }

   for (x = 0; x < n; x++) {
      ast_channel_lock(c[x]);
      if (!ast_tvzero(*ast_channel_whentohangup(c[x]))) {
         if (ast_tvzero(whentohangup))
            now = ast_tvnow();
         diff = ast_tvsub(*ast_channel_whentohangup(c[x]), now);
         if (diff.tv_sec < 0 || ast_tvzero(diff)) {
            ast_test_suite_event_notify("HANGUP_TIME", "Channel: %s", ast_channel_name(c[x]));
            /* Should already be hungup */
            ast_channel_softhangup_internal_flag_add(c[x], AST_SOFTHANGUP_TIMEOUT);
            ast_channel_unlock(c[x]);
            return c[x];
         }
         if (ast_tvzero(whentohangup) || ast_tvcmp(diff, whentohangup) < 0)
            whentohangup = diff;
      }
      sz += ast_channel_fd_count(c[x]);
      ast_channel_unlock(c[x]);
   }

   if (!sz) {
      return NULL;
   }

   pfds = ast_alloca(sizeof(*pfds) * sz);
   fdmap = ast_alloca(sizeof(*fdmap) * sz);

   /* Wait full interval */
   rms = *ms;
   /* INT_MAX, not LONG_MAX, because it matters on 64-bit */
   if (!ast_tvzero(whentohangup) && whentohangup.tv_sec < INT_MAX / 1000) {
      rms = whentohangup.tv_sec * 1000 + whentohangup.tv_usec / 1000;              /* timeout in milliseconds */
      if (*ms >= 0 && *ms < rms) {                                                 /* original *ms still smaller */
         rms =  *ms;
      }
   } else if (!ast_tvzero(whentohangup) && rms < 0) {
      /* Tiny corner case... call would need to last >24 days */
      rms = INT_MAX;
   }
   /*
    * Build the pollfd array, putting the channels' fds first,
    * followed by individual fds. Order is important because
    * individual fd's must have priority over channel fds.
    */
   max = 0;
   for (x = 0; x < n; x++) {
      ast_channel_lock(c[x]);
      for (y = 0; y < ast_channel_fd_count(c[x]); y++) {
         fdmap[max].fdno = y;  /* fd y is linked to this pfds */
         fdmap[max].chan = x;  /* channel x is linked to this pfds */
         max += ast_add_fd(&pfds[max], ast_channel_fd(c[x], y));
      }
      CHECK_BLOCKING(c[x]);
      ast_channel_unlock(c[x]);
   }
   /* Add the individual fds */
   for (x = 0; x < nfds; x++) {
      fdmap[max].chan = -1;
      max += ast_add_fd(&pfds[max], fds[x]);
   }

   if (*ms > 0) {
      start = ast_tvnow();
   }

   if (sizeof(int) == 4) { /* XXX fix timeout > 600000 on linux x86-32 */
      do {
         int kbrms = rms;
         if (kbrms > 600000) {
            kbrms = 600000;
         }
         res = ast_poll(pfds, max, kbrms);
         if (!res) {
            rms -= kbrms;
         }
      } while (!res && (rms > 0));
   } else {
      res = ast_poll(pfds, max, rms);
   }
   for (x = 0; x < n; x++) {
      ast_channel_lock(c[x]);
      ast_clear_flag(ast_channel_flags(c[x]), AST_FLAG_BLOCKING);
      ast_channel_unlock(c[x]);
   }
   if (res < 0) { /* Simulate a timeout if we were interrupted */
      if (errno != EINTR) {
         *ms = -1;
      }
      return NULL;
   }
   if (!ast_tvzero(whentohangup)) {   /* if we have a timeout, check who expired */
      now = ast_tvnow();
      for (x = 0; x < n; x++) {
         if (!ast_tvzero(*ast_channel_whentohangup(c[x])) && ast_tvcmp(*ast_channel_whentohangup(c[x]), now) <= 0) {
            ast_test_suite_event_notify("HANGUP_TIME", "Channel: %s", ast_channel_name(c[x]));
            ast_channel_softhangup_internal_flag_add(c[x], AST_SOFTHANGUP_TIMEOUT);
            if (winner == NULL) {
               winner = c[x];
            }
         }
      }
   }
   if (res == 0) { /* no fd ready, reset timeout and done */
      *ms = 0; /* XXX use 0 since we may not have an exact timeout. */
      return winner;
   }
   /*
    * Then check if any channel or fd has a pending event.
    * Remember to check channels first and fds last, as they
    * must have priority on setting 'winner'
    */
   for (x = 0; x < max; x++) {
      res = pfds[x].revents;
      if (res == 0) {
         continue;
      }
      if (fdmap[x].chan >= 0) {  /* this is a channel */
         winner = c[fdmap[x].chan]; /* override previous winners */
         ast_channel_lock(winner);
         if (res & POLLPRI) {
            ast_set_flag(ast_channel_flags(winner), AST_FLAG_EXCEPTION);
         } else {
            ast_clear_flag(ast_channel_flags(winner), AST_FLAG_EXCEPTION);
         }
         ast_channel_fdno_set(winner, fdmap[x].fdno);
         ast_channel_unlock(winner);
      } else {       /* this is an fd */
         if (outfd) {
            *outfd = pfds[x].fd;
         }
         if (exception) {
            *exception = (res & POLLPRI) ? -1 : 0;
         }
         winner = NULL;
      }
   }
   if (*ms > 0) {
      *ms -= ast_tvdiff_ms(ast_tvnow(), start);
      if (*ms < 0) {
         *ms = 0;
      }
   }
   return winner;
}

struct ast_channel *ast_waitfor_n(struct ast_channel **c, int n, int *ms)
{
   return ast_waitfor_nandfds(c, n, NULL, 0, NULL, NULL, ms);
}

int ast_waitfor(struct ast_channel *c, int ms)
{
   if (ms < 0) {
      do {
         ms = 100000;
         ast_waitfor_nandfds(&c, 1, NULL, 0, NULL, NULL, &ms);
      } while (!ms);
   } else {
      ast_waitfor_nandfds(&c, 1, NULL, 0, NULL, NULL, &ms);
   }
   return ms;
}

int ast_waitfordigit(struct ast_channel *c, int ms)
{
   return ast_waitfordigit_full(c, ms, NULL, -1, -1);
}

int ast_settimeout(struct ast_channel *c, unsigned int rate, int (*func)(const void *data), void *data)
{
   return ast_settimeout_full(c, rate, func, data, 0);
}

int ast_settimeout_full(struct ast_channel *c, unsigned int rate, int (*func)(const void *data), void *data, unsigned int is_ao2_obj)
{
   int res;
   unsigned int real_rate = rate, max_rate;

   ast_channel_lock(c);

   if (ast_channel_timingfd(c) == -1) {
      ast_channel_unlock(c);
      return -1;
   }

   if (!func) {
      rate = 0;
      data = NULL;
   }

   if (rate && rate > (max_rate = ast_timer_get_max_rate(ast_channel_timer(c)))) {
      real_rate = max_rate;
   }

   ast_debug(1, "Scheduling timer at (%u requested / %u actual) timer ticks per second\n", rate, real_rate);

   res = ast_timer_set_rate(ast_channel_timer(c), real_rate);

   if (ast_channel_timingdata(c) && ast_test_flag(ast_channel_flags(c), AST_FLAG_TIMINGDATA_IS_AO2_OBJ)) {
      ao2_ref(ast_channel_timingdata(c), -1);
   }

   ast_channel_timingfunc_set(c, func);
   ast_channel_timingdata_set(c, data);

   if (data && is_ao2_obj) {
      ao2_ref(data, 1);
      ast_set_flag(ast_channel_flags(c), AST_FLAG_TIMINGDATA_IS_AO2_OBJ);
   } else {
      ast_clear_flag(ast_channel_flags(c), AST_FLAG_TIMINGDATA_IS_AO2_OBJ);
   }

   if (func == NULL && rate == 0 && ast_channel_fdno(c) == AST_TIMING_FD) {
      /* Clearing the timing func and setting the rate to 0
       * means that we don't want to be reading from the timingfd
       * any more. Setting c->fdno to -1 means we won't have any
       * errant reads from the timingfd, meaning we won't potentially
       * miss any important frames.
       */
      ast_channel_fdno_set(c, -1);
   }

   ast_channel_unlock(c);

   return res;
}

int ast_waitfordigit_full(struct ast_channel *c, int timeout_ms, const char *breakon, int audiofd, int cmdfd)
{
   struct timeval start = ast_tvnow();
   int ms;

   /* Stop if we're a zombie or need a soft hangup */
   if (ast_test_flag(ast_channel_flags(c), AST_FLAG_ZOMBIE) || ast_check_hangup(c))
      return -1;

   /* Only look for the end of DTMF, don't bother with the beginning and don't emulate things */
   ast_channel_set_flag(c, AST_FLAG_END_DTMF_ONLY);

   /* Wait for a digit, no more than timeout_ms milliseconds total.
    * Or, wait indefinitely if timeout_ms is <0.
    */
   while ((ms = ast_remaining_ms(start, timeout_ms))) {
      struct ast_channel *rchan;
      int outfd = -1;

      errno = 0;
      /* While ast_waitfor_nandfds tries to help by reducing the timeout by how much was waited,
       * it is unhelpful if it waited less than a millisecond.
       */
      rchan = ast_waitfor_nandfds(&c, 1, &cmdfd, (cmdfd > -1) ? 1 : 0, NULL, &outfd, &ms);

      if (!rchan && outfd < 0 && ms) {
         if (errno == 0 || errno == EINTR)
            continue;
         ast_log(LOG_WARNING, "Wait failed (%s)\n", strerror(errno));
         ast_channel_clear_flag(c, AST_FLAG_END_DTMF_ONLY);
         return -1;
      } else if (outfd > -1) {
         /* The FD we were watching has something waiting */
         ast_log(LOG_WARNING, "The FD we were waiting for has something waiting. Waitfordigit returning numeric 1\n");
         ast_channel_clear_flag(c, AST_FLAG_END_DTMF_ONLY);
         return 1;
      } else if (rchan) {
         int res;
         struct ast_frame *f = ast_read(c);

         if (!f) {
            ast_channel_clear_flag(c, AST_FLAG_END_DTMF_ONLY);

            return -1;
         }

         switch (f->frametype) {
         case AST_FRAME_DTMF_BEGIN:
            break;
         case AST_FRAME_DTMF_END:
            res = f->subclass.integer;
            if (!breakon || strchr(breakon, res)) {
               ast_frfree(f);
               ast_channel_clear_flag(c, AST_FLAG_END_DTMF_ONLY);
               return res;
            }
            break;
         case AST_FRAME_CONTROL:
            switch (f->subclass.integer) {
            case AST_CONTROL_HANGUP:
               ast_frfree(f);
               ast_channel_clear_flag(c, AST_FLAG_END_DTMF_ONLY);
               return -1;
            case AST_CONTROL_STREAM_STOP:
            case AST_CONTROL_STREAM_SUSPEND:
            case AST_CONTROL_STREAM_RESTART:
            case AST_CONTROL_STREAM_REVERSE:
            case AST_CONTROL_STREAM_FORWARD:
               /* Fall-through and treat as if it were a DTMF signal. Items
                * that perform stream control will handle this. */
               res = f->subclass.integer;
               ast_frfree(f);
               ast_channel_clear_flag(c, AST_FLAG_END_DTMF_ONLY);
               return res;
            case AST_CONTROL_PVT_CAUSE_CODE:
            case AST_CONTROL_RINGING:
            case AST_CONTROL_ANSWER:
            case AST_CONTROL_SRCUPDATE:
            case AST_CONTROL_SRCCHANGE:
            case AST_CONTROL_CONNECTED_LINE:
            case AST_CONTROL_REDIRECTING:
            case AST_CONTROL_UPDATE_RTP_PEER:
            case AST_CONTROL_HOLD:
            case AST_CONTROL_UNHOLD:
            case -1:
               /* Unimportant */
               break;
            default:
               ast_log(LOG_WARNING, "Unexpected control subclass '%d'\n", f->subclass.integer);
               break;
            }
            break;
         case AST_FRAME_VOICE:
            /* Write audio if appropriate */
            if (audiofd > -1) {
               if (write(audiofd, f->data.ptr, f->datalen) < 0) {
                  ast_log(LOG_WARNING, "write() failed: %s\n", strerror(errno));
               }
            }
         default:
            /* Ignore */
            break;
         }
         ast_frfree(f);
      }
   }

   ast_channel_clear_flag(c, AST_FLAG_END_DTMF_ONLY);

   return 0; /* Time is up */
}

enum DtmfDirection {
   DTMF_RECEIVED,
   DTMF_SENT
};

static const char *dtmf_direction_to_string(enum DtmfDirection direction)
{
   switch (direction) {
   case DTMF_RECEIVED:
      return "Received";
   case DTMF_SENT:
      return "Sent";
   }

   return "?";
}

static void send_dtmf_begin_event(struct ast_channel *chan,
   enum DtmfDirection direction, const char digit)
{
   RAII_VAR(struct ast_json *, blob, NULL, ast_json_unref);
   char digit_str[] = { digit, '\0' };

   blob = ast_json_pack("{ s: s, s: s }",
      "digit", digit_str,
      "direction", dtmf_direction_to_string(direction));
   if (!blob) {
      return;
   }

   ast_channel_publish_blob(chan, ast_channel_dtmf_begin_type(), blob);
}

static void send_dtmf_end_event(struct ast_channel *chan,
   enum DtmfDirection direction, const char digit, long duration_ms)
{
   RAII_VAR(struct ast_json *, blob, NULL, ast_json_unref);
   char digit_str[] = { digit, '\0' };

   blob = ast_json_pack("{ s: s, s: s, s: I }",
      "digit", digit_str,
      "direction", dtmf_direction_to_string(direction),
      "duration_ms", (ast_json_int_t)duration_ms);
   if (!blob) {
      return;
   }

   ast_channel_publish_blob(chan, ast_channel_dtmf_end_type(), blob);
}

static void ast_read_generator_actions(struct ast_channel *chan, struct ast_frame *f)
{
   struct ast_generator *generator;
   void *gendata;
   int res;
   int samples;

   generator = ast_channel_generator(chan);
   if (!generator
      || !generator->generate
      || f->frametype != AST_FRAME_VOICE
      || !ast_channel_generatordata(chan)
      || ast_channel_timingfunc(chan)) {
      return;
   }

   /*
    * We must generate frames in phase locked mode since
    * we have no internal timer available.
    */
   if (ast_format_cmp(f->subclass.format, ast_channel_writeformat(chan)) == AST_FORMAT_CMP_NOT_EQUAL) {
      float factor;
      factor = ((float) ast_format_get_sample_rate(ast_channel_writeformat(chan))) / ((float) ast_format_get_sample_rate(f->subclass.format));
      samples = (int) (((float) f->samples) * factor);
   } else {
      samples = f->samples;
   }

   gendata = ast_channel_generatordata(chan);
   ast_channel_generatordata_set(chan, NULL);     /* reset, to let writes go through */

   /*
    * This unlock is here based on two assumptions that hold true at
    * this point in the code. 1) this function is only called from
    * within __ast_read() and 2) all generators call ast_write() in
    * their generate callback.
    *
    * The reason this is added is so that when ast_write is called,
    * the lock that occurs there will not recursively lock the
    * channel.  Doing this will allow deadlock avoidance to work in
    * deeper functions.
    */
   ast_channel_unlock(chan);
   res = generator->generate(chan, gendata, f->datalen, samples);
   ast_channel_lock(chan);
   if (generator == ast_channel_generator(chan)) {
      ast_channel_generatordata_set(chan, gendata);
      if (res) {
         ast_debug(1, "Auto-deactivating generator\n");
         ast_deactivate_generator(chan);
      }
   }
}

static inline void queue_dtmf_readq(struct ast_channel *chan, struct ast_frame *f)
{
   struct ast_frame *fr = ast_channel_dtmff(chan);

   fr->frametype = AST_FRAME_DTMF_END;
   fr->subclass.integer = f->subclass.integer;
   fr->len = f->len;

   /* The only time this function will be called is for a frame that just came
    * out of the channel driver.  So, we want to stick it on the tail of the
    * readq. */

   ast_queue_frame(chan, fr);
}

/*!
 * \brief Determine whether or not we should ignore DTMF in the readq
 */
static inline int should_skip_dtmf(struct ast_channel *chan)
{
   if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_DEFER_DTMF | AST_FLAG_EMULATE_DTMF)) {
      /* We're in the middle of emulating a digit, or DTMF has been
       * explicitly deferred.  Skip this digit, then. */
      return 1;
   }

   if (!ast_tvzero(*ast_channel_dtmf_tv(chan)) &&
         ast_tvdiff_ms(ast_tvnow(), *ast_channel_dtmf_tv(chan)) < AST_MIN_DTMF_GAP) {
      /* We're not in the middle of a digit, but it hasn't been long enough
       * since the last digit, so we'll have to skip DTMF for now. */
      return 1;
   }

   return 0;
}

/*!
 * \brief calculates the number of samples to jump forward with in a monitor stream.

 * \note When using ast_seekstream() with the read and write streams of a monitor,
 * the number of samples to seek forward must be of the same sample rate as the stream
 * or else the jump will not be calculated correctly.
 *
 * \retval number of samples to seek forward after rate conversion.
 */
static inline int calc_monitor_jump(int samples, int sample_rate, int seek_rate)
{
   int diff = sample_rate - seek_rate;

   if (diff > 0) {
      samples = samples / (float) (sample_rate / seek_rate);
   } else if (diff < 0) {
      samples = samples * (float) (seek_rate / sample_rate);
   }

   return samples;
}

static struct ast_frame *__ast_read(struct ast_channel *chan, int dropaudio, int dropnondefault)
{
   struct ast_frame *f = NULL;   /* the return value */
   int prestate;
   int cause = 0;
   struct ast_stream *stream = NULL, *default_stream = NULL;

   /* this function is very long so make sure there is only one return
    * point at the end (there are only two exceptions to this).
    */
   ast_channel_lock(chan);

   /* Stop if we're a zombie or need a soft hangup */
   if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_ZOMBIE) || ast_check_hangup(chan)) {
      if (ast_channel_generator(chan))
         ast_deactivate_generator(chan);

      /*
       * It is possible for chan->_softhangup to be set and there
       * still be control frames that need to be read.  Instead of
       * just going to 'done' in the case of ast_check_hangup(), we
       * need to queue the end-of-Q frame so that it can mark the end
       * of the read queue.  If there are frames to be read,
       * ast_queue_control() will be called repeatedly, but will only
       * queue the first end-of-Q frame.
       */
      if (ast_channel_softhangup_internal_flag(chan)) {
         ast_queue_control(chan, AST_CONTROL_END_OF_Q);
      } else {
         goto done;
      }
   } else {
#ifdef AST_DEVMODE
      /*
       * The ast_waitfor() code records which of the channel's file
       * descriptors reported that data is available.  In theory,
       * ast_read() should only be called after ast_waitfor() reports
       * that a channel has data available for reading.  However,
       * there still may be some edge cases throughout the code where
       * ast_read() is called improperly.  This can potentially cause
       * problems, so if this is a developer build, make a lot of
       * noise if this happens so that it can be addressed.
       *
       * One of the potential problems is blocking on a dead channel.
       */
      if (ast_channel_fdno(chan) == -1) {
         ast_log(LOG_ERROR,
            "ast_read() on chan '%s' called with no recorded file descriptor.\n",
            ast_channel_name(chan));
      }
#endif
   }

   prestate = ast_channel_state(chan);

   if (ast_channel_timingfd(chan) > -1 && ast_channel_fdno(chan) == AST_TIMING_FD) {
      enum ast_timer_event res;
      int trigger_dtmf_emulating = should_trigger_dtmf_emulating(chan);

      ast_clear_flag(ast_channel_flags(chan), AST_FLAG_EXCEPTION);

      res = ast_timer_get_event(ast_channel_timer(chan));

      switch (res) {
      case AST_TIMING_EVENT_EXPIRED:
         if (ast_timer_ack(ast_channel_timer(chan), 1) < 0) {
            ast_log(LOG_ERROR, "Failed to acknoweldge timer in ast_read\n");
            goto done;
         }

         if (ast_channel_timingfunc(chan)) {
            /* save a copy of func/data before unlocking the channel */
            ast_timing_func_t func = ast_channel_timingfunc(chan);
            void *data = ast_channel_timingdata(chan);
            int got_ref = 0;
            if (data && ast_test_flag(ast_channel_flags(chan), AST_FLAG_TIMINGDATA_IS_AO2_OBJ)) {
               ao2_ref(data, 1);
               got_ref = 1;
            }
            ast_channel_fdno_set(chan, -1);
            ast_channel_unlock(chan);
            func(data);
            if (got_ref) {
               ao2_ref(data, -1);
            }

            if (trigger_dtmf_emulating) {
               /*
                * Since we're breaking out of this switch block and not
                * returning, we need to re-lock the channel.
                */
               ast_channel_lock(chan);
               /* generate null frame to trigger dtmf emulating */
               f = &ast_null_frame;
               break;
            }
         } else if (trigger_dtmf_emulating) {
            /* generate null frame to trigger dtmf emualating */
            f = &ast_null_frame;
            break;
         } else {
            ast_timer_set_rate(ast_channel_timer(chan), 0);
            /* generate very last null frame to trigger dtmf emulating */
            f = &ast_null_frame;
            break;
         }

         /* cannot 'goto done' because the channel is already unlocked */
         return &ast_null_frame;

      case AST_TIMING_EVENT_CONTINUOUS:
         if (AST_LIST_EMPTY(ast_channel_readq(chan)) ||
            !AST_LIST_NEXT(AST_LIST_FIRST(ast_channel_readq(chan)), frame_list)) {
            ast_timer_disable_continuous(ast_channel_timer(chan));
         }
         break;
      }

   } else if (ast_channel_fd_isset(chan, AST_GENERATOR_FD) && ast_channel_fdno(chan) == AST_GENERATOR_FD) {
      /* if the AST_GENERATOR_FD is set, call the generator with args
       * set to -1 so it can do whatever it needs to.
       */
      void *tmp = ast_channel_generatordata(chan);
      ast_channel_generatordata_set(chan, NULL);     /* reset to let ast_write get through */
      ast_channel_generator(chan)->generate(chan, tmp, -1, -1);
      ast_channel_generatordata_set(chan, tmp);
      f = &ast_null_frame;
      ast_channel_fdno_set(chan, -1);
      goto done;
   } else if (ast_channel_fd_isset(chan, AST_JITTERBUFFER_FD) && ast_channel_fdno(chan) == AST_JITTERBUFFER_FD) {
      ast_clear_flag(ast_channel_flags(chan), AST_FLAG_EXCEPTION);
   }

   /* Read and ignore anything on the alertpipe, but read only
      one sizeof(blah) per frame that we send from it */
   if (ast_channel_internal_alert_read(chan) == AST_ALERT_READ_FATAL) {
      f = &ast_null_frame;
      goto done;
   }

   /* Check for pending read queue */
   if (!AST_LIST_EMPTY(ast_channel_readq(chan))) {
      int skipped_dtmf_frame = 0;
      int skip_dtmf = should_skip_dtmf(chan);

      AST_LIST_TRAVERSE_SAFE_BEGIN(ast_channel_readq(chan), f, frame_list) {
         /* We have to be picky about which frame we pull off of the readq because
          * there are cases where we want to leave DTMF frames on the queue until
          * some later time. */

         if ( (f->frametype == AST_FRAME_DTMF_BEGIN || f->frametype == AST_FRAME_DTMF_END) && skip_dtmf) {
            skipped_dtmf_frame = 1;
            continue;
         }

         AST_LIST_REMOVE_CURRENT(frame_list);
         break;
      }
      AST_LIST_TRAVERSE_SAFE_END;

      if (!f) {
         /* There were no acceptable frames on the readq. */
         f = &ast_null_frame;
         if (!skipped_dtmf_frame) {
            /*
             * Do not trigger alert pipe if only buffered dtmf begin or end frames
             * are left in the readq.
             */
            ast_channel_alert_write(chan);
         } else {
            /*
             * Safely disable continous timer events if only buffered dtmf begin or end
             * frames are left in the readq.
             */
            ast_timer_disable_continuous(ast_channel_timer(chan));
         }
      }

      /* Interpret hangup and end-of-Q frames to return NULL */
      /* XXX why not the same for frames from the channel ? */
      if (f->frametype == AST_FRAME_CONTROL) {
         switch (f->subclass.integer) {
         case AST_CONTROL_HANGUP:
            ast_channel_softhangup_internal_flag_add(chan, AST_SOFTHANGUP_DEV);
            cause = f->data.uint32;
            /* Fall through */
         case AST_CONTROL_END_OF_Q:
            ast_frfree(f);
            f = NULL;
            break;
         default:
            break;
         }
      } else if (f->frametype == AST_FRAME_VOICE || f->frametype == AST_FRAME_VIDEO) {
         if (ast_channel_tech(chan) && ast_channel_tech(chan)->read_stream) {
            stream = ast_stream_topology_get_stream(ast_channel_get_stream_topology(chan), f->stream_num);
            default_stream = ast_channel_get_default_stream(chan, ast_format_get_type(f->subclass.format));
         } else {
            /* Since this channel driver does not support multistream determine the default stream this frame
             * originated from and update the frame to include it.
             */
            stream = default_stream = ast_channel_get_default_stream(chan, ast_format_get_type(f->subclass.format));
            /* In order to allow media to be passed up the underlying media type has to have a format negotiated on
             * the channel itself. In cases where this hasn't happened the channel driver is incorrectly passing up
             * a frame for a format that has not been negotiated. If this occurs just drop the frame as we have no
             * stream that it came from.
             */
            if (!stream) {
               ast_frfree(f);
               f = &ast_null_frame;
            } else {
               f->stream_num = ast_stream_get_position(stream);
            }
         }
      }
   } else {
      if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_EXCEPTION)) {
         if (ast_channel_tech(chan)->exception)
            f = ast_channel_tech(chan)->exception(chan);
         else {
            ast_log(LOG_WARNING, "Exception flag set on '%s', but no exception handler\n", ast_channel_name(chan));
            f = &ast_null_frame;
         }
         /* Clear the exception flag */
         ast_clear_flag(ast_channel_flags(chan), AST_FLAG_EXCEPTION);
      } else if (ast_channel_tech(chan) && ast_channel_tech(chan)->read_stream) {
         f = ast_channel_tech(chan)->read_stream(chan);

         /* This channel driver supports multistream so the stream_num on the frame is valid, the only
          * thing different is that we need to find the default stream so we know whether to invoke the
          * default stream logic or not (such as transcoding).
          */
         if (f && (f->frametype == AST_FRAME_VOICE || f->frametype == AST_FRAME_VIDEO)) {
            stream = ast_stream_topology_get_stream(ast_channel_get_stream_topology(chan), f->stream_num);
            default_stream = ast_channel_get_default_stream(chan, ast_format_get_type(f->subclass.format));
         }
      } else if (ast_channel_tech(chan) && ast_channel_tech(chan)->read) {
         f = ast_channel_tech(chan)->read(chan);

         /* Since this channel driver does not support multistream determine the default stream this frame
          * originated from and update the frame to include it.
          */
         if (f && (f->frametype == AST_FRAME_VOICE || f->frametype == AST_FRAME_VIDEO)) {
            stream = default_stream = ast_channel_get_default_stream(chan, ast_format_get_type(f->subclass.format));
            if (!stream) {
               ast_frfree(f);
               f = &ast_null_frame;
            } else {
               f->stream_num = ast_stream_get_position(stream);
            }
         }
      }
      else
         ast_log(LOG_WARNING, "No read routine on channel %s\n", ast_channel_name(chan));
   }

   if (stream == default_stream) {
      /* Perform the framehook read event here. After the frame enters the framehook list
       * there is no telling what will happen, <insert mad scientist laugh here>!!! */
      f = ast_framehook_list_read_event(ast_channel_framehooks(chan), f);
   }

   /*
    * Reset the recorded file descriptor that triggered this read so that we can
    * easily detect when ast_read() is called without properly using ast_waitfor().
    */
   ast_channel_fdno_set(chan, -1);

   if (f) {
      struct ast_frame *readq_tail = AST_LIST_LAST(ast_channel_readq(chan));
      struct ast_control_read_action_payload *read_action_payload;
      struct ast_party_connected_line connected;
      int hooked = 0;

      /* if the channel driver returned more than one frame, stuff the excess
         into the readq for the next ast_read call
      */
      if (AST_LIST_NEXT(f, frame_list)) {
         ast_queue_frame(chan, AST_LIST_NEXT(f, frame_list));
         ast_frfree(AST_LIST_NEXT(f, frame_list));
         AST_LIST_NEXT(f, frame_list) = NULL;
      }

      if (dropnondefault && stream != default_stream) {
         /* If the frame originates from a non-default stream and the caller can not handle other streams
          * absorb the frame and replace it with a null one instead.
          */
         ast_frfree(f);
         f = &ast_null_frame;
      }

      switch (f->frametype) {
      case AST_FRAME_CONTROL:
         if (f->subclass.integer == AST_CONTROL_ANSWER) {
            if (prestate == AST_STATE_UP && ast_channel_is_bridged(chan)) {
               ast_debug(1, "Dropping duplicate answer!\n");
               ast_frfree(f);
               f = &ast_null_frame;
            } else {
               /*
                * Mark when outgoing channel answered so we can know how
                * long the channel has been up.
                */
               set_channel_answer_time(chan);

               ast_setstate(chan, AST_STATE_UP);
            }
         } else if (f->subclass.integer == AST_CONTROL_READ_ACTION) {
            read_action_payload = f->data.ptr;
            switch (read_action_payload->action) {
            case AST_FRAME_READ_ACTION_CONNECTED_LINE_MACRO:
               ast_party_connected_line_init(&connected);
               ast_party_connected_line_copy(&connected, ast_channel_connected(chan));
               if (ast_connected_line_parse_data(read_action_payload->payload,
                  read_action_payload->payload_size, &connected)) {
                  ast_party_connected_line_free(&connected);
                  break;
               }
               ast_channel_unlock(chan);
               if (ast_channel_connected_line_sub(NULL, chan, &connected, 0) &&
                  ast_channel_connected_line_macro(NULL, chan, &connected, 1, 0)) {
                  ast_indicate_data(chan, AST_CONTROL_CONNECTED_LINE,
                     read_action_payload->payload,
                     read_action_payload->payload_size);
               }
               ast_party_connected_line_free(&connected);
               ast_channel_lock(chan);
               break;
            case AST_FRAME_READ_ACTION_SEND_TEXT:
               ast_channel_unlock(chan);
               ast_sendtext(chan, (const char *)read_action_payload->payload);
               ast_channel_lock(chan);
               break;
            case AST_FRAME_READ_ACTION_SEND_TEXT_DATA:
               ast_channel_unlock(chan);
               ast_sendtext_data(chan, (struct ast_msg_data *)read_action_payload->payload);
               ast_channel_lock(chan);
               break;
            }
            ast_frfree(f);
            f = &ast_null_frame;
         } else if (f->subclass.integer == AST_CONTROL_STREAM_TOPOLOGY_REQUEST_CHANGE && dropnondefault) {
            /* The caller of this function is incapable of handling streams so we don't accept the change request
             * and stick to the streams currently on the channel.
             */
            ast_channel_stream_topology_changed(chan, ast_channel_get_stream_topology(chan));
            ast_frfree(f);
            f = &ast_null_frame;
         } else if (f->subclass.integer == AST_CONTROL_STREAM_TOPOLOGY_CHANGED && dropnondefault) {
            /* The caller of this function is incapable of handling streams so we absorb the notification that the
             * stream topology has changed.
             */
            ast_frfree(f);
            f = &ast_null_frame;
         }
         break;
      case AST_FRAME_DTMF_END:
         send_dtmf_end_event(chan, DTMF_RECEIVED, f->subclass.integer, f->len);
         ast_log(LOG_DTMF, "DTMF end '%c' received on %s, duration %ld ms\n", f->subclass.integer, ast_channel_name(chan), f->len);
         /* Queue it up if DTMF is deferred, or if DTMF emulation is forced. */
         if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_DEFER_DTMF) || ast_test_flag(ast_channel_flags(chan), AST_FLAG_EMULATE_DTMF)) {
            queue_dtmf_readq(chan, f);
            ast_frfree(f);
            f = &ast_null_frame;
         } else if (!ast_test_flag(ast_channel_flags(chan), AST_FLAG_IN_DTMF | AST_FLAG_END_DTMF_ONLY)) {
            if (!ast_tvzero(*ast_channel_dtmf_tv(chan)) &&
                ast_tvdiff_ms(ast_tvnow(), *ast_channel_dtmf_tv(chan)) < AST_MIN_DTMF_GAP) {
               /* If it hasn't been long enough, defer this digit */
               queue_dtmf_readq(chan, f);
               ast_frfree(f);
               f = &ast_null_frame;
            } else {
               /* There was no begin, turn this into a begin and send the end later */
               struct timeval tv = ast_tvnow();
               f->frametype = AST_FRAME_DTMF_BEGIN;
               ast_set_flag(ast_channel_flags(chan), AST_FLAG_EMULATE_DTMF);
               ast_channel_dtmf_digit_to_emulate_set(chan, f->subclass.integer);
               ast_channel_dtmf_tv_set(chan, &tv);
               if (f->len) {
                  if (f->len > option_dtmfminduration)
                     ast_channel_emulate_dtmf_duration_set(chan, f->len);
                  else
                     ast_channel_emulate_dtmf_duration_set(chan, option_dtmfminduration);
               } else
                  ast_channel_emulate_dtmf_duration_set(chan, AST_DEFAULT_EMULATE_DTMF_DURATION);
               ast_log(LOG_DTMF, "DTMF begin emulation of '%c' with duration %u queued on %s\n", f->subclass.integer, ast_channel_emulate_dtmf_duration(chan), ast_channel_name(chan));

               /*
                * Start generating 50 fps timer events (null frames) for dtmf emulating
                * independently from any existing incoming voice frames.
                * If channel generator is already activated in regular mode use these
                * timer events to generate null frames.
                */
               if (!ast_channel_generator(chan)) {
                  ast_timer_set_rate(ast_channel_timer(chan), 50);
               }
            }
            if (ast_channel_audiohooks(chan)) {
               struct ast_frame *old_frame = f;
               /*!
                * \todo XXX It is possible to write a digit to the audiohook twice
                * if the digit was originally read while the channel was in autoservice. */
               f = ast_audiohook_write_list(chan, ast_channel_audiohooks(chan), AST_AUDIOHOOK_DIRECTION_READ, f);
               if (old_frame != f)
                  ast_frfree(old_frame);
            }
         } else {
            struct timeval now = ast_tvnow();
            if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_IN_DTMF)) {
               ast_log(LOG_DTMF, "DTMF end accepted with begin '%c' on %s\n", f->subclass.integer, ast_channel_name(chan));
               ast_clear_flag(ast_channel_flags(chan), AST_FLAG_IN_DTMF);
               if (!f->len)
                  f->len = ast_tvdiff_ms(now, *ast_channel_dtmf_tv(chan));

               /* detect tones that were received on
                * the wire with durations shorter than
                * option_dtmfminduration and set f->len
                * to the actual duration of the DTMF
                * frames on the wire.  This will cause
                * dtmf emulation to be triggered later
                * on.
                */
               if (ast_tvdiff_ms(now, *ast_channel_dtmf_tv(chan)) < option_dtmfminduration) {
                  f->len = ast_tvdiff_ms(now, *ast_channel_dtmf_tv(chan));
                  ast_log(LOG_DTMF, "DTMF end '%c' detected to have actual duration %ld on the wire, emulation will be triggered on %s\n", f->subclass.integer, f->len, ast_channel_name(chan));
               }
            } else if (!f->len) {
               ast_log(LOG_DTMF, "DTMF end accepted without begin '%c' on %s\n", f->subclass.integer, ast_channel_name(chan));
               f->len = option_dtmfminduration;
            }
            if (f->len < option_dtmfminduration && !ast_test_flag(ast_channel_flags(chan), AST_FLAG_END_DTMF_ONLY)) {
               ast_log(LOG_DTMF, "DTMF end '%c' has duration %ld but want minimum %u, emulating on %s\n", f->subclass.integer, f->len, option_dtmfminduration, ast_channel_name(chan));
               ast_set_flag(ast_channel_flags(chan), AST_FLAG_EMULATE_DTMF);
               ast_channel_dtmf_digit_to_emulate_set(chan, f->subclass.integer);
               ast_channel_emulate_dtmf_duration_set(chan, option_dtmfminduration - f->len);
               ast_frfree(f);
               f = &ast_null_frame;

               /* Start generating 50 fps timer events (null frames) for dtmf emulating
                * independently from any existing incoming voice frames.
                * If channel generator is already activated in regular mode use these
                * timer events to generate null frames.
                */
               if (!ast_channel_generator(chan)) {
                  ast_timer_set_rate(ast_channel_timer(chan), 50);
               }
            } else {
               ast_log(LOG_DTMF, "DTMF end passthrough '%c' on %s\n", f->subclass.integer, ast_channel_name(chan));
               if (f->len < option_dtmfminduration) {
                  f->len = option_dtmfminduration;
               }
               ast_channel_dtmf_tv_set(chan, &now);

               /* Start generating 50 fps timer events (null frames) for dtmf emulating
                * independently from any existing incoming voice frames.
                * If channel generator is already activated in regular mode use these
                * timer events to generate null frames.
                */
               if (!ast_channel_generator(chan)) {
                  ast_timer_set_rate(ast_channel_timer(chan), 50);
               }
            }
            if (ast_channel_audiohooks(chan)) {
               struct ast_frame *old_frame = f;
               f = ast_audiohook_write_list(chan, ast_channel_audiohooks(chan), AST_AUDIOHOOK_DIRECTION_READ, f);
               if (old_frame != f)
                  ast_frfree(old_frame);
            }
         }
         break;
      case AST_FRAME_DTMF_BEGIN:
         send_dtmf_begin_event(chan, DTMF_RECEIVED, f->subclass.integer);
         ast_log(LOG_DTMF, "DTMF begin '%c' received on %s\n", f->subclass.integer, ast_channel_name(chan));
         if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_DEFER_DTMF | AST_FLAG_END_DTMF_ONLY | AST_FLAG_EMULATE_DTMF) ||
             (!ast_tvzero(*ast_channel_dtmf_tv(chan)) &&
               ast_tvdiff_ms(ast_tvnow(), *ast_channel_dtmf_tv(chan)) < AST_MIN_DTMF_GAP) ) {
            ast_log(LOG_DTMF, "DTMF begin ignored '%c' on %s\n", f->subclass.integer, ast_channel_name(chan));
            ast_frfree(f);
            f = &ast_null_frame;
         } else {
            struct timeval now = ast_tvnow();
            ast_set_flag(ast_channel_flags(chan), AST_FLAG_IN_DTMF);
            ast_channel_dtmf_tv_set(chan, &now);
            ast_log(LOG_DTMF, "DTMF begin passthrough '%c' on %s\n", f->subclass.integer, ast_channel_name(chan));
         }
         break;
      case AST_FRAME_NULL:
         /* The EMULATE_DTMF flag must be cleared here as opposed to when the duration
          * is reached , because we want to make sure we pass at least one
          * voice frame through before starting the next digit, to ensure a gap
          * between DTMF digits. */
         if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_EMULATE_DTMF)) {
            struct timeval now = ast_tvnow();
            if (!ast_channel_emulate_dtmf_duration(chan)) {
               ast_clear_flag(ast_channel_flags(chan), AST_FLAG_EMULATE_DTMF);
               ast_channel_dtmf_digit_to_emulate_set(chan, 0);
            } else if (ast_tvdiff_ms(now, *ast_channel_dtmf_tv(chan)) >= ast_channel_emulate_dtmf_duration(chan)) {
               ast_channel_emulate_dtmf_duration_set(chan, 0);
               ast_frfree(f);
               f = ast_channel_dtmff(chan);
               f->frametype = AST_FRAME_DTMF_END;
               f->subclass.integer = ast_channel_dtmf_digit_to_emulate(chan);
               f->len = ast_tvdiff_ms(now, *ast_channel_dtmf_tv(chan));
               ast_channel_dtmf_tv_set(chan, &now);
               ast_clear_flag(ast_channel_flags(chan), AST_FLAG_EMULATE_DTMF);
               ast_channel_dtmf_digit_to_emulate_set(chan, 0);
               ast_log(LOG_DTMF, "DTMF end emulation of '%c' queued on %s\n", f->subclass.integer, ast_channel_name(chan));
               if (ast_channel_audiohooks(chan)) {
                  struct ast_frame *old_frame = f;
                  f = ast_audiohook_write_list(chan, ast_channel_audiohooks(chan), AST_AUDIOHOOK_DIRECTION_READ, f);
                  if (old_frame != f) {
                     ast_frfree(old_frame);
                  }
               }

               /* Start generating 50 fps timer events (null frames) for dtmf emulating
                * independently from any existing incoming voice frames.
                * If channel generator is already activated in regular mode use these
                * timer events to generate null frames.
                */
               if (!ast_channel_generator(chan)) {
                  ast_timer_set_rate(ast_channel_timer(chan), 50);
               }
            }
         }
         break;
      case AST_FRAME_VOICE:
         /* If media was received from a non-default stream don't perform any actions, let it just go through */
         if (stream != default_stream) {
            break;
         }

         /* The EMULATE_DTMF flag must be cleared here as opposed to when the duration
          * is reached , because we want to make sure we pass at least one
          * voice frame through before starting the next digit, to ensure a gap
          * between DTMF digits. */
         if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_EMULATE_DTMF) && !ast_channel_emulate_dtmf_duration(chan)) {
            ast_clear_flag(ast_channel_flags(chan), AST_FLAG_EMULATE_DTMF);
            ast_channel_dtmf_digit_to_emulate_set(chan, 0);
         }

         if (dropaudio || ast_test_flag(ast_channel_flags(chan), AST_FLAG_IN_DTMF)) {
            if (dropaudio)
               ast_read_generator_actions(chan, f);
            ast_frfree(f);
            f = &ast_null_frame;
         }

         if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_EMULATE_DTMF) && !ast_test_flag(ast_channel_flags(chan), AST_FLAG_IN_DTMF)) {
            struct timeval now = ast_tvnow();
            if (ast_tvdiff_ms(now, *ast_channel_dtmf_tv(chan)) >= ast_channel_emulate_dtmf_duration(chan)) {
               ast_channel_emulate_dtmf_duration_set(chan, 0);
               ast_frfree(f);
               f = ast_channel_dtmff(chan);
               f->frametype = AST_FRAME_DTMF_END;
               f->subclass.integer = ast_channel_dtmf_digit_to_emulate(chan);
               f->len = ast_tvdiff_ms(now, *ast_channel_dtmf_tv(chan));
               ast_channel_dtmf_tv_set(chan, &now);
               if (ast_channel_audiohooks(chan)) {
                  struct ast_frame *old_frame = f;
                  f = ast_audiohook_write_list(chan, ast_channel_audiohooks(chan), AST_AUDIOHOOK_DIRECTION_READ, f);
                  if (old_frame != f)
                     ast_frfree(old_frame);
               }
               ast_log(LOG_DTMF, "DTMF end emulation of '%c' queued on %s\n", f->subclass.integer, ast_channel_name(chan));
            } else {
               /* Drop voice frames while we're still in the middle of the digit */
               ast_frfree(f);
               f = &ast_null_frame;
            }
            break;
         }
         if (f->frametype != AST_FRAME_VOICE) {
            break;
         }
         if (ast_format_cmp(f->subclass.format, ast_channel_rawreadformat(chan)) != AST_FORMAT_CMP_EQUAL
            && ast_format_cmp(f->subclass.format, ast_channel_readformat(chan)) != AST_FORMAT_CMP_EQUAL) {
            struct ast_format *core_format;

            /*
             * Note: This frame may not be one of the current native
             * formats.  We may have gotten it out of the read queue from
             * a previous multi-frame translation, from a framehook
             * injected frame, or the device we're talking to isn't
             * respecting negotiated formats.  Regardless we will accept
             * all frames.
             *
             * Update the read translation path to handle the new format
             * that just came in.  If the core wants slinear we need to
             * setup a new translation path because the core is usually
             * doing something with the audio itself and may not handle
             * any other format.  e.g., Softmix bridge, holding bridge
             * announcer channel, recording, AMD...  Otherwise, we'll
             * setup to pass the frame as is to the core.  In this case
             * the core doesn't care.  The channel is likely in
             * autoservice, safesleep, or the channel is in a bridge.
             * Let the bridge technology deal with format compatibility
             * between the channels in the bridge.
             *
             * Beware of the transcode_via_slin and genericplc options as
             * they force any transcoding to go through slin on a bridge.
             * Unfortunately transcode_via_slin is enabled by default and
             * genericplc is enabled in the codecs.conf.sample file.
             *
             * XXX Only updating translation to slinear frames has some
             * corner cases if slinear is one of the native formats and
             * there are different sample rates involved.  We might wind
             * up with conflicting translation paths between channels
             * where the read translation path on this channel reduces
             * the sample rate followed by a write translation path on
             * the peer channel that increases the sample rate.
             */
            core_format = ast_channel_readformat(chan);
            if (!ast_format_cache_is_slinear(core_format)) {
               core_format = f->subclass.format;
            }
            if (ast_set_read_format_path(chan, f->subclass.format, core_format)) {
               /* Drop frame.  We couldn't make it compatible with the core. */
               ast_frfree(f);
               f = &ast_null_frame;
               break;
            }
         }
         /*
          * Send frame to audiohooks if present, if frametype is linear, to preserve
          * functional compatibility with previous behavior. If not linear, hold off
          * until transcoding is done where we are more likely to have a linear frame
          */
         if (ast_channel_audiohooks(chan) && ast_format_cache_is_slinear(f->subclass.format)) {
            /* Place hooked after declaration */
            struct ast_frame *old_frame = f;
            hooked = 1;

            f = ast_audiohook_write_list(chan, ast_channel_audiohooks(chan), AST_AUDIOHOOK_DIRECTION_READ, f);
            if (old_frame != f) {
               ast_frfree(old_frame);
            }
         }

         if (ast_channel_monitor(chan) && ast_channel_monitor(chan)->read_stream) {
            /* XXX what does this do ? */
#ifndef MONITOR_CONSTANT_DELAY
            int jump = ast_channel_outsmpl(chan) - ast_channel_insmpl(chan) - 4 * f->samples;
            if (jump >= 0) {
               jump = calc_monitor_jump((ast_channel_outsmpl(chan) - ast_channel_insmpl(chan)),
                  ast_format_get_sample_rate(f->subclass.format),
                  ast_format_get_sample_rate(ast_channel_monitor(chan)->read_stream->fmt->format));
               if (ast_seekstream(ast_channel_monitor(chan)->read_stream, jump, SEEK_FORCECUR) == -1) {
                  ast_log(LOG_WARNING, "Failed to perform seek in monitoring read stream, synchronization between the files may be broken\n");
               }
               ast_channel_insmpl_set(chan, ast_channel_insmpl(chan) + (ast_channel_outsmpl(chan) - ast_channel_insmpl(chan)) + f->samples);
            } else {
               ast_channel_insmpl_set(chan, ast_channel_insmpl(chan) + f->samples);
            }
#else
            int jump = calc_monitor_jump((ast_channel_outsmpl(chan) - ast_channel_insmpl(chan)),
               ast_format_get_sample_rate(f->subclass.format),
               ast_format_get_sample_rate(ast_channel_monitor(chan)->read_stream->fmt->format));
            if (jump - MONITOR_DELAY >= 0) {
               if (ast_seekstream(ast_channel_monitor(chan)->read_stream, jump - f->samples, SEEK_FORCECUR) == -1) {
                  ast_log(LOG_WARNING, "Failed to perform seek in monitoring read stream, synchronization between the files may be broken\n");
               }
               ast_channel_insmpl(chan) += ast_channel_outsmpl(chan) - ast_channel_insmpl(chan);
            } else {
               ast_channel_insmpl(chan) += f->samples;
            }
#endif
            if (ast_channel_monitor(chan)->state == AST_MONITOR_RUNNING) {
               if (ast_writestream(ast_channel_monitor(chan)->read_stream, f) < 0)
                  ast_log(LOG_WARNING, "Failed to write data to channel monitor read stream\n");
            }
         }

         if (ast_channel_readtrans(chan)
            && ast_format_cmp(f->subclass.format, ast_channel_rawreadformat(chan)) == AST_FORMAT_CMP_EQUAL) {
            f = ast_translate(ast_channel_readtrans(chan), f, 1);
            if (!f) {
               f = &ast_null_frame;
            }
         }

         /* Second chance at hooking a linear frame, also the last chance */
         if (ast_channel_audiohooks(chan) && !hooked) {
            struct ast_frame *old_frame = f;

            f = ast_audiohook_write_list(chan, ast_channel_audiohooks(chan), AST_AUDIOHOOK_DIRECTION_READ, f);
            if (old_frame != f) {
               ast_frfree(old_frame);
            }
         }

         /*
          * It is possible for the translation process on the channel to have
          * produced multiple frames from the single input frame we passed it; if
          * this happens, queue the additional frames *before* the frames we may
          * have queued earlier. if the readq was empty, put them at the head of
          * the queue, and if it was not, put them just after the frame that was
          * at the end of the queue.
          */
         if (AST_LIST_NEXT(f, frame_list)) {
            struct ast_frame *cur, *multi_frame = AST_LIST_NEXT(f, frame_list);

            /* Mark these frames as being re-queued */
            for (cur = multi_frame; cur; cur = AST_LIST_NEXT(cur, frame_list)) {
               ast_set_flag(cur, AST_FRFLAG_REQUEUED);
            }

            if (!readq_tail) {
               ast_queue_frame_head(chan, multi_frame);
            } else {
               __ast_queue_frame(chan, multi_frame, 0, readq_tail);
            }
            ast_frfree(multi_frame);
            AST_LIST_NEXT(f, frame_list) = NULL;
         }

         /*
          * Run generator sitting on the line if timing device not available
          * and synchronous generation of outgoing frames is necessary
          */
         ast_read_generator_actions(chan, f);
         break;
      case AST_FRAME_RTCP:
         /* Incoming RTCP feedback needs to get to the translator for
          * outgoing media, which means we treat it as an ast_write */
         if (ast_channel_writetrans(chan)) {
            ast_translate(ast_channel_writetrans(chan), f, 0);
         }
         break;
      default:
         /* Just pass it on! */
         break;
      }
   } else {
      /* Make sure we always return NULL in the future */
      if (!ast_channel_softhangup_internal_flag(chan)) {
         ast_channel_softhangup_internal_flag_add(chan, AST_SOFTHANGUP_DEV);
      }
      if (cause)
         ast_channel_hangupcause_set(chan, cause);
      if (ast_channel_generator(chan))
         ast_deactivate_generator(chan);
      /* We no longer End the CDR here */
   }

   /* High bit prints debugging */
   if (ast_channel_fin(chan) & DEBUGCHAN_FLAG)
      ast_frame_dump(ast_channel_name(chan), f, "<<");
   ast_channel_fin_set(chan, FRAMECOUNT_INC(ast_channel_fin(chan)));

done:
   if (ast_channel_music_state(chan) && ast_channel_generator(chan) && ast_channel_generator(chan)->digit && f && f->frametype == AST_FRAME_DTMF_END)
      ast_channel_generator(chan)->digit(chan, f->subclass.integer);

   if (ast_channel_audiohooks(chan) && ast_audiohook_write_list_empty(ast_channel_audiohooks(chan))) {
      /* The list gets recreated if audiohooks are added again later */
      ast_audiohook_detach_list(ast_channel_audiohooks(chan));
      ast_channel_audiohooks_set(chan, NULL);
   }
   ast_channel_unlock(chan);
   return f;
}

struct ast_frame *ast_read(struct ast_channel *chan)
{
   return __ast_read(chan, 0, 1);
}

struct ast_frame *ast_read_stream(struct ast_channel *chan)
{
   return __ast_read(chan, 0, 0);
}

struct ast_frame *ast_read_noaudio(struct ast_channel *chan)
{
   return __ast_read(chan, 1, 1);
}

struct ast_frame *ast_read_stream_noaudio(struct ast_channel *chan)
{
   return __ast_read(chan, 1, 0);
}

int ast_indicate(struct ast_channel *chan, int condition)
{
   return ast_indicate_data(chan, condition, NULL, 0);
}

static int attribute_const is_visible_indication(enum ast_control_frame_type condition)
{
   /* Don't include a default case here so that we get compiler warnings
    * when a new type is added. */

   switch (condition) {
   case AST_CONTROL_PROGRESS:
   case AST_CONTROL_PROCEEDING:
   case AST_CONTROL_VIDUPDATE:
   case AST_CONTROL_SRCUPDATE:
   case AST_CONTROL_SRCCHANGE:
   case AST_CONTROL_RADIO_KEY:
   case AST_CONTROL_RADIO_UNKEY:
   case AST_CONTROL_OPTION:
   case AST_CONTROL_WINK:
   case AST_CONTROL_FLASH:
   case AST_CONTROL_OFFHOOK:
   case AST_CONTROL_TAKEOFFHOOK:
   case AST_CONTROL_ANSWER:
   case AST_CONTROL_HANGUP:
   case AST_CONTROL_CONNECTED_LINE:
   case AST_CONTROL_REDIRECTING:
   case AST_CONTROL_TRANSFER:
   case AST_CONTROL_T38_PARAMETERS:
   case _XXX_AST_CONTROL_T38:
   case AST_CONTROL_CC:
   case AST_CONTROL_READ_ACTION:
   case AST_CONTROL_AOC:
   case AST_CONTROL_END_OF_Q:
   case AST_CONTROL_MCID:
   case AST_CONTROL_UPDATE_RTP_PEER:
   case AST_CONTROL_PVT_CAUSE_CODE:
   case AST_CONTROL_MASQUERADE_NOTIFY:
   case AST_CONTROL_STREAM_TOPOLOGY_REQUEST_CHANGE:
   case AST_CONTROL_STREAM_TOPOLOGY_CHANGED:
   case AST_CONTROL_STREAM_TOPOLOGY_SOURCE_CHANGED:
   case AST_CONTROL_STREAM_STOP:
   case AST_CONTROL_STREAM_SUSPEND:
   case AST_CONTROL_STREAM_REVERSE:
   case AST_CONTROL_STREAM_FORWARD:
   case AST_CONTROL_STREAM_RESTART:
   case AST_CONTROL_RECORD_CANCEL:
   case AST_CONTROL_RECORD_STOP:
   case AST_CONTROL_RECORD_SUSPEND:
   case AST_CONTROL_RECORD_MUTE:
      break;

   case AST_CONTROL_INCOMPLETE:
   case AST_CONTROL_CONGESTION:
   case AST_CONTROL_BUSY:
   case AST_CONTROL_RINGING:
   case AST_CONTROL_RING:
   case AST_CONTROL_HOLD:
      /* You can hear these */
      return 1;

   case AST_CONTROL_UNHOLD:
      /* This is a special case.  You stop hearing this. */
      break;
   }

   return 0;
}

void ast_channel_hangupcause_hash_set(struct ast_channel *chan, const struct ast_control_pvt_cause_code *cause_code, int datalen)
{
   char causevar[256];

   if (ast_channel_dialed_causes_add(chan, cause_code, datalen)) {
      ast_log(LOG_WARNING, "Unable to store hangup cause for %s on %s\n", cause_code->chan_name, ast_channel_name(chan));
   }

   if (cause_code->emulate_sip_cause) {
      snprintf(causevar, sizeof(causevar), "HASH(SIP_CAUSE,%s)", cause_code->chan_name);
      ast_func_write(chan, causevar, cause_code->code);
   }
}

enum ama_flags ast_channel_string2amaflag(const char *flag)
{
   if (!strcasecmp(flag, "default"))
      return DEFAULT_AMA_FLAGS;
   if (!strcasecmp(flag, "omit"))
      return AST_AMA_OMIT;
   if (!strcasecmp(flag, "billing"))
      return AST_AMA_BILLING;
   if (!strcasecmp(flag, "documentation"))
      return AST_AMA_DOCUMENTATION;
   return AST_AMA_NONE;
}

const char *ast_channel_amaflags2string(enum ama_flags flag)
{
   switch (flag) {
   case AST_AMA_OMIT:
      return "OMIT";
   case AST_AMA_BILLING:
      return "BILLING";
   case AST_AMA_DOCUMENTATION:
      return "DOCUMENTATION";
   default:
      return "Unknown";
   }
}

/*!
 * \internal
 * \brief Preprocess connected line update.
 * \since 12.0.0
 *
 * \param chan channel to change the indication
 * \param data pointer to payload data
 * \param datalen size of payload data
 *
 * \note This function assumes chan is locked.
 *
 * \retval 0 keep going.
 * \retval -1 quit now.
 */
static int indicate_connected_line(struct ast_channel *chan, const void *data, size_t datalen)
{
   struct ast_party_connected_line *chan_connected = ast_channel_connected(chan);
   struct ast_party_connected_line *chan_indicated = ast_channel_connected_indicated(chan);
   struct ast_party_connected_line connected;
   unsigned char current[1024];
   unsigned char proposed[1024];
   int current_size;
   int proposed_size;
   int res;

   ast_party_connected_line_set_init(&connected, chan_connected);
   res = ast_connected_line_parse_data(data, datalen, &connected);
   if (!res) {
      ast_channel_set_connected_line(chan, &connected, NULL);
   }
   ast_party_connected_line_free(&connected);
   if (res) {
      return -1;
   }

   current_size = ast_connected_line_build_data(current, sizeof(current),
      chan_indicated, NULL);
   proposed_size = ast_connected_line_build_data(proposed, sizeof(proposed),
      chan_connected, NULL);
   if (current_size == -1 || proposed_size == -1) {
      return -1;
   }

   if (current_size == proposed_size && !memcmp(current, proposed, current_size)) {
      ast_debug(1, "%s: Dropping redundant connected line update \"%s\" <%s>.\n",
         ast_channel_name(chan),
         S_COR(chan_connected->id.name.valid, chan_connected->id.name.str, ""),
         S_COR(chan_connected->id.number.valid, chan_connected->id.number.str, ""));
      return -1;
   }

   ast_party_connected_line_copy(chan_indicated, chan_connected);
   return 0;
}

/*!
 * \internal
 * \brief Preprocess redirecting update.
 * \since 12.0.0
 *
 * \param chan channel to change the indication
 * \param data pointer to payload data
 * \param datalen size of payload data
 *
 * \note This function assumes chan is locked.
 *
 * \retval 0 keep going.
 * \retval -1 quit now.
 */
static int indicate_redirecting(struct ast_channel *chan, const void *data, size_t datalen)
{
   struct ast_party_redirecting redirecting;
   int res;

   ast_party_redirecting_set_init(&redirecting, ast_channel_redirecting(chan));
   res = ast_redirecting_parse_data(data, datalen, &redirecting);
   if (!res) {
      ast_channel_set_redirecting(chan, &redirecting, NULL);
   }
   ast_party_redirecting_free(&redirecting);
   return res ? -1 : 0;
}

static int indicate_data_internal(struct ast_channel *chan, int _condition, const void *data, size_t datalen)
{
   /* By using an enum, we'll get compiler warnings for values not handled
    * in switch statements. */
   enum ast_control_frame_type condition = _condition;
   struct ast_tone_zone_sound *ts = NULL;
   const struct ast_control_t38_parameters *t38_parameters;
   int res;

   switch (condition) {
   case AST_CONTROL_CONNECTED_LINE:
      if (indicate_connected_line(chan, data, datalen)) {
         res = 0;
         return res;
      }
      break;
   case AST_CONTROL_REDIRECTING:
      if (indicate_redirecting(chan, data, datalen)) {
         res = 0;
         return res;
      }
      break;
   case AST_CONTROL_HOLD:
   case AST_CONTROL_UNHOLD:
      ast_channel_hold_state_set(chan, _condition);
      break;
   case AST_CONTROL_T38_PARAMETERS:
      t38_parameters = data;
      switch (t38_parameters->request_response) {
      case AST_T38_REQUEST_NEGOTIATE:
      case AST_T38_NEGOTIATED:
         ast_channel_set_is_t38_active_nolock(chan, 1);
         break;
      case AST_T38_REQUEST_TERMINATE:
      case AST_T38_TERMINATED:
      case AST_T38_REFUSED:
         ast_channel_set_is_t38_active_nolock(chan, 0);
         break;
      default:
         break;
      }
      break;
   default:
      break;
   }

   if (is_visible_indication(condition)) {
      /* A new visible indication is requested. */
      ast_channel_visible_indication_set(chan, _condition);
   } else if (condition == AST_CONTROL_UNHOLD || _condition < 0) {
      /* Visible indication is cleared/stopped. */
      ast_channel_visible_indication_set(chan, 0);
   }

   if (ast_channel_tech(chan)->indicate) {
      /* See if the channel driver can handle this condition. */
      res = ast_channel_tech(chan)->indicate(chan, _condition, data, datalen);
   } else {
      res = -1;
   }

   if (!res) {
      /* The channel driver successfully handled this indication */
      res = 0;
      return res;
   }

   /* The channel driver does not support this indication, let's fake
    * it by doing our own tone generation if applicable. */

   /*!\note If we compare the enumeration type, which does not have any
    * negative constants, the compiler may optimize this code away.
    * Therefore, we must perform an integer comparison here. */
   if (_condition < 0) {
      /* Stop any tones that are playing */
      ast_playtones_stop(chan);
      res = 0;
      return res;
   }

   /* Handle conditions that we have tones for. */
   switch (condition) {
   case _XXX_AST_CONTROL_T38:
      /* deprecated T.38 control frame */
      res = -1;
      return res;
   case AST_CONTROL_T38_PARAMETERS:
      /* there is no way to provide 'default' behavior for these
       * control frames, so we need to return failure, but there
       * is also no value in the log message below being emitted
       * since failure to handle these frames is not an 'error'
       * so just return right now. in addition, we want to return
       * whatever value the channel driver returned, in case it
       * has some meaning.*/
      return res;
   case AST_CONTROL_RINGING:
      ts = ast_get_indication_tone(ast_channel_zone(chan), "ring");
      /* It is common practice for channel drivers to return -1 if trying
       * to indicate ringing on a channel which is up. The idea is to let the
       * core generate the ringing inband. However, we don't want the
       * warning message about not being able to handle the specific indication
       * to print nor do we want ast_indicate_data to return an "error" for this
       * condition
       */
      if (ast_channel_state(chan) == AST_STATE_UP) {
         res = 0;
      }
      break;
   case AST_CONTROL_BUSY:
      ts = ast_get_indication_tone(ast_channel_zone(chan), "busy");
      break;
   case AST_CONTROL_INCOMPLETE:
   case AST_CONTROL_CONGESTION:
      ts = ast_get_indication_tone(ast_channel_zone(chan), "congestion");
      break;
   case AST_CONTROL_PVT_CAUSE_CODE:
      ast_channel_hangupcause_hash_set(chan, data, datalen);
      res = 0;
      break;
   case AST_CONTROL_PROGRESS:
   case AST_CONTROL_PROCEEDING:
   case AST_CONTROL_VIDUPDATE:
   case AST_CONTROL_SRCUPDATE:
   case AST_CONTROL_SRCCHANGE:
   case AST_CONTROL_RADIO_KEY:
   case AST_CONTROL_RADIO_UNKEY:
   case AST_CONTROL_OPTION:
   case AST_CONTROL_WINK:
   case AST_CONTROL_FLASH:
   case AST_CONTROL_OFFHOOK:
   case AST_CONTROL_TAKEOFFHOOK:
   case AST_CONTROL_ANSWER:
   case AST_CONTROL_HANGUP:
   case AST_CONTROL_RING:
   case AST_CONTROL_HOLD:
   case AST_CONTROL_UNHOLD:
   case AST_CONTROL_TRANSFER:
   case AST_CONTROL_CONNECTED_LINE:
   case AST_CONTROL_REDIRECTING:
   case AST_CONTROL_CC:
   case AST_CONTROL_READ_ACTION:
   case AST_CONTROL_AOC:
   case AST_CONTROL_END_OF_Q:
   case AST_CONTROL_MCID:
   case AST_CONTROL_MASQUERADE_NOTIFY:
   case AST_CONTROL_UPDATE_RTP_PEER:
   case AST_CONTROL_STREAM_TOPOLOGY_REQUEST_CHANGE:
   case AST_CONTROL_STREAM_TOPOLOGY_CHANGED:
   case AST_CONTROL_STREAM_TOPOLOGY_SOURCE_CHANGED:
   case AST_CONTROL_STREAM_STOP:
   case AST_CONTROL_STREAM_SUSPEND:
   case AST_CONTROL_STREAM_REVERSE:
   case AST_CONTROL_STREAM_FORWARD:
   case AST_CONTROL_STREAM_RESTART:
   case AST_CONTROL_RECORD_CANCEL:
   case AST_CONTROL_RECORD_STOP:
   case AST_CONTROL_RECORD_SUSPEND:
   case AST_CONTROL_RECORD_MUTE:
      /* Nothing left to do for these. */
      res = 0;
      break;
   }

   if (ts) {
      /* We have a tone to play, yay. */
      ast_debug(1, "Driver for channel '%s' does not support indication %u, emulating it\n", ast_channel_name(chan), condition);
      res = ast_playtones_start(chan, 0, ts->data, 1);
      if (!res) {
         ast_test_suite_event_notify("RINGING_INBAND",
               "Channel: %s\r\n",
               ast_channel_name(chan));
      }
      ts = ast_tone_zone_sound_unref(ts);
   }

   if (res) {
      /* not handled */
      ast_log(LOG_WARNING, "Unable to handle indication %u for '%s'\n", condition, ast_channel_name(chan));
   }

   return res;
}

int ast_indicate_data(struct ast_channel *chan, int _condition, const void *data, size_t datalen)
{
   int res;
   /* this frame is used by framehooks. if it is set, we must free it at the end of this function */
   struct ast_frame *awesome_frame = NULL;

   ast_channel_lock(chan);

   /* Don't bother if the channel is about to go away, anyway. */
   if ((ast_test_flag(ast_channel_flags(chan), AST_FLAG_ZOMBIE)
         || (ast_check_hangup(chan) && !ast_channel_is_leaving_bridge(chan)))
      && _condition != AST_CONTROL_MASQUERADE_NOTIFY) {
      res = -1;
      goto indicate_cleanup;
   }

   if (!ast_framehook_list_is_empty(ast_channel_framehooks(chan))) {
      /* Do framehooks now, do it, go, go now */
      struct ast_frame frame = {
         .frametype = AST_FRAME_CONTROL,
         .subclass.integer = _condition,
         .data.ptr = (void *) data, /* this cast from const is only okay because we do the ast_frdup below */
         .datalen = datalen
      };

      /* we have now committed to freeing this frame */
      awesome_frame = ast_frdup(&frame);

      /* who knows what we will get back! the anticipation is killing me. */
      awesome_frame = ast_framehook_list_write_event(ast_channel_framehooks(chan),
         awesome_frame);
      if (!awesome_frame
         || awesome_frame->frametype != AST_FRAME_CONTROL) {
         res = 0;
         goto indicate_cleanup;
      }

      _condition = awesome_frame->subclass.integer;
      data = awesome_frame->data.ptr;
      datalen = awesome_frame->datalen;
   }

   res = indicate_data_internal(chan, _condition, data, datalen);

indicate_cleanup:
   ast_channel_unlock(chan);
   if (awesome_frame) {
      ast_frfree(awesome_frame);
   }

   return res;
}

int ast_recvchar(struct ast_channel *chan, int timeout)
{
   int c;
   char *buf = ast_recvtext(chan, timeout);
   if (buf == NULL)
      return -1;  /* error or timeout */
   c = *(unsigned char *)buf;
   ast_free(buf);
   return c;
}

char *ast_recvtext(struct ast_channel *chan, int timeout)
{
   int res;
   char *buf = NULL;
   struct timeval start = ast_tvnow();
   int ms;

   while ((ms = ast_remaining_ms(start, timeout))) {
      struct ast_frame *f;

      if (ast_check_hangup(chan)) {
         break;
      }
      res = ast_waitfor(chan, ms);
      if (res <= 0)  {/* timeout or error */
         break;
      }
      f = ast_read(chan);
      if (f == NULL) {
         break; /* no frame */
      }
      if (f->frametype == AST_FRAME_CONTROL && f->subclass.integer == AST_CONTROL_HANGUP) {
         ast_frfree(f);
         break;
      } else if (f->frametype == AST_FRAME_TEXT) {    /* what we want */
         buf = ast_strndup((char *) f->data.ptr, f->datalen);  /* dup and break */
         ast_frfree(f);
         break;
      }
      ast_frfree(f);
   }
   return buf;
}

int ast_sendtext_data(struct ast_channel *chan, struct ast_msg_data *msg)
{
   int res = 0;
   const char *body = ast_msg_data_get_attribute(msg, AST_MSG_DATA_ATTR_BODY);
   const char *content_type = ast_msg_data_get_attribute(msg, AST_MSG_DATA_ATTR_CONTENT_TYPE);

   ast_channel_lock(chan);
   /* Stop if we're a zombie or need a soft hangup */
   if (ast_test_flag(ast_channel_flags(chan), AST_FLAG_ZOMBIE) || ast_check_hangup(chan)) {
      ast_channel_unlock(chan);
      return -1;
   }

   CHECK_BLOCKING(chan);
   if (ast_channel_tech(chan)->write_text
      && (ast_strlen_zero(content_type) || ast_begins_with(content_type, "text/"))
      && (ast_format_cap_has_type(ast_channel_nativeformats(chan), AST_MEDIA_TYPE_TEXT))) {
      struct ast_frame f;
      /* T.140 payload does not include the null byte terminator */
      size_t body_len = strlen(body);

      /* Process as T.140 text (moved here from ast_sendtext() */
      memset(&f, 0, sizeof(f));
      f.src = "DIALPLAN";
      f.subclass.format = ast_format_t140;
      f.frametype = AST_FRAME_TEXT;
      f.datalen = body_len;
      f.mallocd = AST_MALLOCD_DATA;
      f.data.ptr = ast_strdup(body);
      if (f.data.ptr) {
         res = ast_channel_tech(chan)->write_text(chan, &f);
      } else {
         res = -1;
      }
      ast_frfree(&f);
   } else if ((ast_channel_tech(chan)->properties & AST_CHAN_TP_SEND_TEXT_DATA)
      && ast_channel_tech(chan)->send_text_data) {
      /* Send enhanced message to a channel driver that supports it */
      ast_debug(1, "Sending TEXT_DATA from '%s' to %s:%s %s\n",
         ast_msg_data_get_attribute(msg, AST_MSG_DATA_ATTR_FROM),
         ast_msg_data_get_attribute(msg, AST_MSG_DATA_ATTR_TO),
         ast_channel_name(chan), body);
      res = ast_channel_tech(chan)->send_text_data(chan, msg);
   } else if (ast_channel_tech(chan)->send_text
      && (ast_strlen_zero(content_type) || ast_begins_with(content_type, "text/"))) {
      /* Send the body of an enhanced message to a channel driver that supports only a char str */