cel.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2007 - 2009, Digium, Inc.
 *
 * 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 Event Logging API
 *
 * \author Steve Murphy <[email protected]>
 * \author Russell Bryant <[email protected]>
 */

/*! \li \ref cel.c uses the configuration file \ref cel.conf
 * \addtogroup configuration_file Configuration Files
 */

/*!
 * \page cel.conf cel.conf
 * \verbinclude cel.conf.sample
 */

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

#include "asterisk.h"

#include "asterisk/module.h"

#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/cel.h"
#include "asterisk/logger.h"
#include "asterisk/linkedlists.h"
#include "asterisk/utils.h"
#include "asterisk/config.h"
#include "asterisk/config_options.h"
#include "asterisk/cli.h"
#include "asterisk/astobj2.h"
#include "asterisk/stasis_message_router.h"
#include "asterisk/stasis_channels.h"
#include "asterisk/stasis_bridges.h"
#include "asterisk/bridge.h"
#include "asterisk/parking.h"
#include "asterisk/pickup.h"
#include "asterisk/core_local.h"
#include "asterisk/taskprocessor.h"

/*** DOCUMENTATION
   <configInfo name="cel" language="en_US">
      <configFile name="cel.conf">
         <configObject name="general">
            <synopsis>Options that apply globally to Channel Event Logging (CEL)</synopsis>
            <configOption name="enable">
               <synopsis>Determines whether CEL is enabled</synopsis>
            </configOption>
            <configOption name="dateformat">
               <synopsis>The format to be used for dates when logging</synopsis>
            </configOption>
            <configOption name="apps">
               <synopsis>List of apps for CEL to track</synopsis>
               <description><para>A case-insensitive, comma-separated list of applications
               to track when one or both of APP_START and APP_END events are flagged for
               tracking</para></description>
            </configOption>
            <configOption name="events">
               <synopsis>List of events for CEL to track</synopsis>
               <description><para>A case-sensitive, comma-separated list of event names
               to track. These event names do not include the leading <literal>AST_CEL</literal>.
               </para>
               <enumlist>
                  <enum name="ALL">
                     <para>Special value which tracks all events.</para>
                  </enum>
                  <enum name="CHAN_START"/>
                  <enum name="CHAN_END"/>
                  <enum name="ANSWER"/>
                  <enum name="HANGUP"/>
                  <enum name="APP_START"/>
                  <enum name="APP_END"/>
                  <enum name="PARK_START"/>
                  <enum name="PARK_END"/>
                  <enum name="USER_DEFINED"/>
                  <enum name="BRIDGE_ENTER"/>
                  <enum name="BRIDGE_EXIT"/>
                  <enum name="BLINDTRANSFER"/>
                  <enum name="ATTENDEDTRANSFER"/>
                  <enum name="PICKUP"/>
                  <enum name="FORWARD"/>
                  <enum name="LINKEDID_END"/>
                  <enum name="LOCAL_OPTIMIZE"/>
               </enumlist>
               </description>
            </configOption>
         </configObject>
      </configFile>
   </configInfo>
 ***/

/*! Message router for state that CEL needs to know about */
static struct stasis_message_router *cel_state_router;

/*! Topic for CEL-specific messages */
static struct stasis_topic *cel_topic;

/*! Aggregation topic for all topics CEL needs to know about */
static struct stasis_topic *cel_aggregation_topic;

/*! Subscription for forwarding the channel caching topic */
static struct stasis_forward *cel_channel_forwarder;

/*! Subscription for forwarding the channel caching topic */
static struct stasis_forward *cel_bridge_forwarder;

/*! Subscription for forwarding the parking topic */
static struct stasis_forward *cel_parking_forwarder;

/*! Subscription for forwarding the CEL-specific topic */
static struct stasis_forward *cel_cel_forwarder;

struct stasis_message_type *cel_generic_type(void);
STASIS_MESSAGE_TYPE_DEFN(cel_generic_type);

/*! Container for CEL backend information */
static AO2_GLOBAL_OBJ_STATIC(cel_backends);

/*! The number of buckets into which backend names will be hashed */
#define BACKEND_BUCKETS 13

/*! Container for dial end multichannel blobs for holding on to dial statuses */
static AO2_GLOBAL_OBJ_STATIC(cel_dialstatus_store);

/*!
 * \brief Maximum possible CEL event IDs
 * \note This limit is currently imposed by the eventset definition
 */
#define CEL_MAX_EVENT_IDS 64

/*!
 * \brief Number of buckets for the appset container
 */
#define NUM_APP_BUCKETS    97

/*!
 * \brief Number of buckets for the dialstatus container
 */
#define NUM_DIALSTATUS_BUCKETS   251

struct cel_linkedid {
   /*! Number of channels with this linkedid. */
   unsigned int count;
   /*! Linkedid stored at end of struct. */
   char id[0];
};

/*! Container of channel references to a linkedid for CEL purposes. */
static AO2_GLOBAL_OBJ_STATIC(cel_linkedids);

struct cel_dialstatus {
   /*! Uniqueid of the channel */
   char uniqueid[AST_MAX_UNIQUEID];
   /*! The dial status */
   char dialstatus[0];
};

/*! \brief Destructor for cel_config */
static void cel_general_config_dtor(void *obj)
{
   struct ast_cel_general_config *cfg = obj;
   ast_string_field_free_memory(cfg);
   ao2_cleanup(cfg->apps);
   cfg->apps = NULL;
}

void *ast_cel_general_config_alloc(void)
{
   RAII_VAR(struct ast_cel_general_config *, cfg, NULL, ao2_cleanup);

   if (!(cfg = ao2_alloc(sizeof(*cfg), cel_general_config_dtor))) {
      return NULL;
   }

   if (ast_string_field_init(cfg, 64)) {
      return NULL;
   }

   if (!(cfg->apps = ast_str_container_alloc(NUM_APP_BUCKETS))) {
      return NULL;
   }

   ao2_ref(cfg, +1);
   return cfg;
}

/*! \brief A container that holds all config-related information */
struct cel_config {
   struct ast_cel_general_config *general;
};


static AO2_GLOBAL_OBJ_STATIC(cel_configs);

/*! \brief Destructor for cel_config */
static void cel_config_dtor(void *obj)
{
   struct cel_config *cfg = obj;
   ao2_cleanup(cfg->general);
   cfg->general = NULL;
}

static void *cel_config_alloc(void)
{
   RAII_VAR(struct cel_config *, cfg, NULL, ao2_cleanup);

   if (!(cfg = ao2_alloc(sizeof(*cfg), cel_config_dtor))) {
      return NULL;
   }

   if (!(cfg->general = ast_cel_general_config_alloc())) {
      return NULL;
   }

   ao2_ref(cfg, +1);
   return cfg;
}

/*! \brief An aco_type structure to link the "general" category to the ast_cel_general_config type */
static struct aco_type general_option = {
   .type = ACO_GLOBAL,
   .name = "general",
   .item_offset = offsetof(struct cel_config, general),
   .category_match = ACO_WHITELIST_EXACT,
   .category = "general",
};

/*! Config sections used by existing modules. Do not add to this list. */
static const char *ignore_categories[] = {
   "manager",
   "radius",
   NULL,
};

static struct aco_type ignore_option = {
   .type = ACO_IGNORE,
   .name = "modules",
   .category = (const char*)ignore_categories,
   .category_match = ACO_WHITELIST_ARRAY,
};

/*! \brief The config file to be processed for the module. */
static struct aco_file cel_conf = {
   .filename = "cel.conf",                  /*!< The name of the config file */
   .types = ACO_TYPES(&general_option, &ignore_option),     /*!< The mapping object types to be processed */
};

static int cel_pre_apply_config(void);

CONFIG_INFO_CORE("cel", cel_cfg_info, cel_configs, cel_config_alloc,
   .files = ACO_FILES(&cel_conf),
   .pre_apply_config = cel_pre_apply_config,
);

static int cel_pre_apply_config(void)
{
   struct cel_config *cfg = aco_pending_config(&cel_cfg_info);

   if (!cfg->general) {
      return -1;
   }

   if (!ao2_container_count(cfg->general->apps)) {
      return 0;
   }

   if (cfg->general->events & ((int64_t) 1 << AST_CEL_APP_START)) {
      return 0;
   }

   if (cfg->general->events & ((int64_t) 1 << AST_CEL_APP_END)) {
      return 0;
   }

   ast_log(LOG_ERROR, "Applications are listed to be tracked, but APP events are not tracked\n");
   return -1;
}

static struct aco_type *general_options[] = ACO_TYPES(&general_option);

/*!
 * \brief Map of ast_cel_event_type to strings
 */
static const char * const cel_event_types[CEL_MAX_EVENT_IDS] = {
   [AST_CEL_ALL]              = "ALL",
   [AST_CEL_CHANNEL_START]    = "CHAN_START",
   [AST_CEL_CHANNEL_END]      = "CHAN_END",
   [AST_CEL_ANSWER]           = "ANSWER",
   [AST_CEL_HANGUP]           = "HANGUP",
   [AST_CEL_APP_START]        = "APP_START",
   [AST_CEL_APP_END]          = "APP_END",
   [AST_CEL_PARK_START]       = "PARK_START",
   [AST_CEL_PARK_END]         = "PARK_END",
   [AST_CEL_USER_DEFINED]     = "USER_DEFINED",
   [AST_CEL_BRIDGE_ENTER]     = "BRIDGE_ENTER",
   [AST_CEL_BRIDGE_EXIT]      = "BRIDGE_EXIT",
   [AST_CEL_BLINDTRANSFER]    = "BLINDTRANSFER",
   [AST_CEL_ATTENDEDTRANSFER] = "ATTENDEDTRANSFER",
   [AST_CEL_PICKUP]           = "PICKUP",
   [AST_CEL_FORWARD]          = "FORWARD",
   [AST_CEL_LINKEDID_END]     = "LINKEDID_END",
   [AST_CEL_LOCAL_OPTIMIZE]   = "LOCAL_OPTIMIZE",
};

struct cel_backend {
   ast_cel_backend_cb callback; /*!< Callback for this backend */
   char name[0];                /*!< Name of this backend */
};

/*! \brief Hashing function for cel_backend */
AO2_STRING_FIELD_HASH_FN(cel_backend, name)

/*! \brief Comparator function for cel_backend */
AO2_STRING_FIELD_CMP_FN(cel_backend, name)

/*! \brief Hashing function for dialstatus container */
AO2_STRING_FIELD_HASH_FN(cel_dialstatus, uniqueid)

/*! \brief Comparator function for dialstatus container */
AO2_STRING_FIELD_CMP_FN(cel_dialstatus, uniqueid)

unsigned int ast_cel_check_enabled(void)
{
   unsigned int enabled;
   struct cel_config *cfg = ao2_global_obj_ref(cel_configs);

   enabled = (!cfg || !cfg->general) ? 0 : cfg->general->enable;
   ao2_cleanup(cfg);
   return enabled;
}

static char *handle_cli_status(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
   unsigned int i;
   RAII_VAR(struct cel_config *, cfg, ao2_global_obj_ref(cel_configs), ao2_cleanup);
   RAII_VAR(struct ao2_container *, backends, ao2_global_obj_ref(cel_backends), ao2_cleanup);
   struct ao2_iterator iter;
   char *app;

   switch (cmd) {
   case CLI_INIT:
      e->command = "cel show status";
      e->usage =
         "Usage: cel show status\n"
         "       Displays the Channel Event Logging system status.\n";
      return NULL;
   case CLI_GENERATE:
      return NULL;
   case CLI_HANDLER:
      break;
   }

   if (a->argc > 3) {
      return CLI_SHOWUSAGE;
   }

   ast_cli(a->fd, "CEL Logging: %s\n", ast_cel_check_enabled() ? "Enabled" : "Disabled");

   if (!cfg || !cfg->general || !cfg->general->enable) {
      return CLI_SUCCESS;
   }

   for (i = 0; i < (sizeof(cfg->general->events) * 8); i++) {
      const char *name;

      if (!(cfg->general->events & ((int64_t) 1 << i))) {
         continue;
      }

      name = ast_cel_get_type_name(i);
      if (strcasecmp(name, "Unknown")) {
         ast_cli(a->fd, "CEL Tracking Event: %s\n", name);
      }
   }

   iter = ao2_iterator_init(cfg->general->apps, 0);
   for (; (app = ao2_iterator_next(&iter)); ao2_ref(app, -1)) {
      ast_cli(a->fd, "CEL Tracking Application: %s\n", app);
   }
   ao2_iterator_destroy(&iter);

   if (backends) {
      struct cel_backend *backend;

      iter = ao2_iterator_init(backends, 0);
      for (; (backend = ao2_iterator_next(&iter)); ao2_ref(backend, -1)) {
         ast_cli(a->fd, "CEL Event Subscriber: %s\n", backend->name);
      }
      ao2_iterator_destroy(&iter);
   }

   return CLI_SUCCESS;
}

static struct ast_cli_entry cli_status = AST_CLI_DEFINE(handle_cli_status, "Display the CEL status");

enum ast_cel_event_type ast_cel_str_to_event_type(const char *name)
{
   unsigned int i;

   for (i = 0; i < ARRAY_LEN(cel_event_types); i++) {
      if (cel_event_types[i] && !strcasecmp(name, cel_event_types[i])) {
         return i;
      }
   }

   ast_log(LOG_ERROR, "Unknown event name '%s'\n", name);
   return AST_CEL_INVALID_VALUE;
}

static int ast_cel_track_event(enum ast_cel_event_type et)
{
   RAII_VAR(struct cel_config *, cfg, ao2_global_obj_ref(cel_configs), ao2_cleanup);

   if (!cfg || !cfg->general) {
      return 0;
   }

   return (cfg->general->events & ((int64_t) 1 << et)) ? 1 : 0;
}

static int events_handler(const struct aco_option *opt, struct ast_variable *var, void *obj)
{
   struct ast_cel_general_config *cfg = obj;
   char *events = ast_strdupa(var->value);
   char *cur_event;

   while ((cur_event = strsep(&events, ","))) {
      enum ast_cel_event_type event_type;

      cur_event = ast_strip(cur_event);
      if (ast_strlen_zero(cur_event)) {
         continue;
      }

      event_type = ast_cel_str_to_event_type(cur_event);

      if (event_type == AST_CEL_ALL) {
         /* All events */
         cfg->events = (int64_t) -1;
      } else if (event_type == AST_CEL_INVALID_VALUE) {
         return -1;
      } else {
         cfg->events |= ((int64_t) 1 << event_type);
      }
   }

   return 0;
}

static int apps_handler(const struct aco_option *opt, struct ast_variable *var, void *obj)
{
   struct ast_cel_general_config *cfg = obj;
   char *apps = ast_strdupa(var->value);
   char *cur_app;

   while ((cur_app = strsep(&apps, ","))) {
      cur_app = ast_strip(cur_app);
      if (ast_strlen_zero(cur_app)) {
         continue;
      }

      cur_app = ast_str_to_lower(cur_app);
      ast_str_container_add(cfg->apps, cur_app);
   }

   return 0;
}

const char *ast_cel_get_type_name(enum ast_cel_event_type type)
{
   return S_OR(cel_event_types[type], "Unknown");
}

static int cel_track_app(const char *const_app)
{
   RAII_VAR(struct cel_config *, cfg, ao2_global_obj_ref(cel_configs), ao2_cleanup);
   RAII_VAR(char *, app, NULL, ao2_cleanup);
   char *app_lower;

   if (!cfg || !cfg->general) {
      return 0;
   }

   app_lower = ast_str_to_lower(ast_strdupa(const_app));
   app = ao2_find(cfg->general->apps, app_lower, OBJ_SEARCH_KEY);
   if (!app) {
      return 0;
   }

   return 1;
}

static int cel_linkedid_ref(const char *linkedid);

struct ast_event *ast_cel_create_event(struct ast_channel_snapshot *snapshot,
      enum ast_cel_event_type event_type, const char *userdefevname,
      struct ast_json *extra, const char *peer)
{
   struct timeval eventtime = ast_tvnow();

   return ast_cel_create_event_with_time(snapshot, event_type, &eventtime,
      userdefevname, extra, peer);
}

struct ast_event *ast_cel_create_event_with_time(struct ast_channel_snapshot *snapshot,
      enum ast_cel_event_type event_type, const struct timeval *event_time,
      const char *userdefevname, struct ast_json *extra, const char *peer)
{
   RAII_VAR(char *, extra_txt, NULL, ast_json_free);
   if (extra) {
      extra_txt = ast_json_dump_string(extra);
   }
   return ast_event_new(AST_EVENT_CEL,
      AST_EVENT_IE_CEL_EVENT_TYPE, AST_EVENT_IE_PLTYPE_UINT, event_type,
      AST_EVENT_IE_CEL_EVENT_TIME, AST_EVENT_IE_PLTYPE_UINT, event_time->tv_sec,
      AST_EVENT_IE_CEL_EVENT_TIME_USEC, AST_EVENT_IE_PLTYPE_UINT, event_time->tv_usec,
      AST_EVENT_IE_CEL_USEREVENT_NAME, AST_EVENT_IE_PLTYPE_STR, S_OR(userdefevname, ""),
      AST_EVENT_IE_CEL_CIDNAME, AST_EVENT_IE_PLTYPE_STR, snapshot->caller->name,
      AST_EVENT_IE_CEL_CIDNUM, AST_EVENT_IE_PLTYPE_STR, snapshot->caller->number,
      AST_EVENT_IE_CEL_CIDANI, AST_EVENT_IE_PLTYPE_STR, snapshot->caller->ani,
      AST_EVENT_IE_CEL_CIDRDNIS, AST_EVENT_IE_PLTYPE_STR, snapshot->caller->rdnis,
      AST_EVENT_IE_CEL_CIDDNID, AST_EVENT_IE_PLTYPE_STR, snapshot->caller->dnid,
      AST_EVENT_IE_CEL_EXTEN, AST_EVENT_IE_PLTYPE_STR, snapshot->dialplan->exten,
      AST_EVENT_IE_CEL_CONTEXT, AST_EVENT_IE_PLTYPE_STR, snapshot->dialplan->context,
      AST_EVENT_IE_CEL_CHANNAME, AST_EVENT_IE_PLTYPE_STR, snapshot->base->name,
      AST_EVENT_IE_CEL_APPNAME, AST_EVENT_IE_PLTYPE_STR, snapshot->dialplan->appl,
      AST_EVENT_IE_CEL_APPDATA, AST_EVENT_IE_PLTYPE_STR, snapshot->dialplan->data,
      AST_EVENT_IE_CEL_AMAFLAGS, AST_EVENT_IE_PLTYPE_UINT, snapshot->amaflags,
      AST_EVENT_IE_CEL_ACCTCODE, AST_EVENT_IE_PLTYPE_STR, snapshot->base->accountcode,
      AST_EVENT_IE_CEL_PEERACCT, AST_EVENT_IE_PLTYPE_STR, snapshot->peer->account,
      AST_EVENT_IE_CEL_UNIQUEID, AST_EVENT_IE_PLTYPE_STR, snapshot->base->uniqueid,
      AST_EVENT_IE_CEL_LINKEDID, AST_EVENT_IE_PLTYPE_STR, snapshot->peer->linkedid,
      AST_EVENT_IE_CEL_USERFIELD, AST_EVENT_IE_PLTYPE_STR, snapshot->base->userfield,
      AST_EVENT_IE_CEL_EXTRA, AST_EVENT_IE_PLTYPE_STR, S_OR(extra_txt, ""),
      AST_EVENT_IE_CEL_PEER, AST_EVENT_IE_PLTYPE_STR, S_OR(peer, ""),
      AST_EVENT_IE_END);
}

static int cel_backend_send_cb(void *obj, void *arg, int flags)
{
   struct cel_backend *backend = obj;

   backend->callback(arg);
   return 0;
}

static int cel_report_event(struct ast_channel_snapshot *snapshot,
      enum ast_cel_event_type event_type, const struct timeval *event_time,
      const char *userdefevname, struct ast_json *extra,
      const char *peer_str)
{
   struct ast_event *ev;
   RAII_VAR(struct cel_config *, cfg, ao2_global_obj_ref(cel_configs), ao2_cleanup);
   RAII_VAR(struct ao2_container *, backends, ao2_global_obj_ref(cel_backends), ao2_cleanup);

   if (!cfg || !cfg->general || !cfg->general->enable || !backends) {
      return 0;
   }

   /* Record the linkedid of new channels if we are tracking LINKEDID_END even if we aren't
    * reporting on CHANNEL_START so we can track when to send LINKEDID_END */
   if (event_type == AST_CEL_CHANNEL_START
      && ast_cel_track_event(AST_CEL_LINKEDID_END)) {
      if (cel_linkedid_ref(snapshot->peer->linkedid)) {
         return -1;
      }
   }

   if (!ast_cel_track_event(event_type)) {
      return 0;
   }

   if ((event_type == AST_CEL_APP_START || event_type == AST_CEL_APP_END)
      && !cel_track_app(snapshot->dialplan->appl)) {
      return 0;
   }

   ev = ast_cel_create_event_with_time(snapshot, event_type, event_time, userdefevname, extra, peer_str);
   if (!ev) {
      return -1;
   }

   /* Distribute event to backends */
   ao2_callback(backends, OBJ_MULTIPLE | OBJ_NODATA, cel_backend_send_cb, ev);
   ast_event_destroy(ev);

   return 0;
}

/* called whenever a channel is destroyed or a linkedid is changed to
 * potentially emit a CEL_LINKEDID_END event */
static void check_retire_linkedid(struct ast_channel_snapshot *snapshot, const struct timeval *event_time)
{
   RAII_VAR(struct ao2_container *, linkedids, ao2_global_obj_ref(cel_linkedids), ao2_cleanup);
   struct cel_linkedid *lid;

   if (!linkedids || ast_strlen_zero(snapshot->peer->linkedid)) {
      /* The CEL module is shutdown.  Abort. */
      return;
   }

   ao2_lock(linkedids);

   lid = ao2_find(linkedids, (void *) snapshot->peer->linkedid, OBJ_SEARCH_KEY);
   if (!lid) {
      ao2_unlock(linkedids);

      /*
       * The user may have done a reload to start tracking linkedids
       * when a call was already in progress.  This is an unusual kind
       * of change to make after starting Asterisk.
       */
      ast_log(LOG_ERROR, "Something weird happened, couldn't find linkedid %s\n",
         snapshot->peer->linkedid);
      return;
   }

   if (!--lid->count) {
      /* No channels use this linkedid anymore. */
      ao2_unlink(linkedids, lid);
      ao2_unlock(linkedids);

      cel_report_event(snapshot, AST_CEL_LINKEDID_END, event_time, NULL, NULL, NULL);
   } else {
      ao2_unlock(linkedids);
   }
   ao2_ref(lid, -1);
}

/* Note that no 'chan_fixup' function is provided for this datastore type,
 * because the channels that will use it will never be involved in masquerades.
 */
static const struct ast_datastore_info fabricated_channel_datastore = {
   .type = "CEL fabricated channel",
   .destroy = ast_free_ptr,
};

struct ast_channel *ast_cel_fabricate_channel_from_event(const struct ast_event *event)
{
   struct varshead *headp;
   struct ast_var_t *newvariable;
   const char *mixed_name;
   char timebuf[30];
   struct ast_channel *tchan;
   struct ast_cel_event_record record = {
      .version = AST_CEL_EVENT_RECORD_VERSION,
   };
   struct ast_datastore *datastore;
   char *app_data;
   RAII_VAR(struct cel_config *, cfg, ao2_global_obj_ref(cel_configs), ao2_cleanup);

   if (!cfg || !cfg->general) {
      return NULL;
   }

   /* do not call ast_channel_alloc because this is not really a real channel */
   if (!(tchan = ast_dummy_channel_alloc())) {
      return NULL;
   }

   headp = ast_channel_varshead(tchan);

   /* first, get the variables from the event */
   if (ast_cel_fill_record(event, &record)) {
      ast_channel_unref(tchan);
      return NULL;
   }

   /* next, fill the channel with their data */
   mixed_name = (record.event_type == AST_CEL_USER_DEFINED)
      ? record.user_defined_name : record.event_name;
   if ((newvariable = ast_var_assign("eventtype", mixed_name))) {
      AST_LIST_INSERT_HEAD(headp, newvariable, entries);
   }

   if (ast_strlen_zero(cfg->general->date_format)) {
      snprintf(timebuf, sizeof(timebuf), "%ld.%06ld", (long) record.event_time.tv_sec,
            (long) record.event_time.tv_usec);
   } else {
      struct ast_tm tm;
      ast_localtime(&record.event_time, &tm, NULL);
      ast_strftime(timebuf, sizeof(timebuf), cfg->general->date_format, &tm);
   }

   if ((newvariable = ast_var_assign("eventtime", timebuf))) {
      AST_LIST_INSERT_HEAD(headp, newvariable, entries);
   }

   if ((newvariable = ast_var_assign("eventenum", record.event_name))) {
      AST_LIST_INSERT_HEAD(headp, newvariable, entries);
   }
   if ((newvariable = ast_var_assign("userdeftype", record.user_defined_name))) {
      AST_LIST_INSERT_HEAD(headp, newvariable, entries);
   }
   if ((newvariable = ast_var_assign("eventextra", record.extra))) {
      AST_LIST_INSERT_HEAD(headp, newvariable, entries);
   }

   ast_channel_caller(tchan)->id.name.valid = 1;
   ast_channel_caller(tchan)->id.name.str = ast_strdup(record.caller_id_name);
   ast_channel_caller(tchan)->id.number.valid = 1;
   ast_channel_caller(tchan)->id.number.str = ast_strdup(record.caller_id_num);
   ast_channel_caller(tchan)->ani.number.valid = 1;
   ast_channel_caller(tchan)->ani.number.str = ast_strdup(record.caller_id_ani);
   ast_channel_redirecting(tchan)->from.number.valid = 1;
   ast_channel_redirecting(tchan)->from.number.str = ast_strdup(record.caller_id_rdnis);
   ast_channel_dialed(tchan)->number.str = ast_strdup(record.caller_id_dnid);

   ast_channel_exten_set(tchan, record.extension);
   ast_channel_context_set(tchan, record.context);
   ast_channel_name_set(tchan, record.channel_name);
   ast_channel_internal_set_fake_ids(tchan, record.unique_id, record.linked_id);
   ast_channel_accountcode_set(tchan, record.account_code);
   ast_channel_peeraccount_set(tchan, record.peer_account);
   ast_channel_userfield_set(tchan, record.user_field);

   if ((newvariable = ast_var_assign("BRIDGEPEER", record.peer))) {
      AST_LIST_INSERT_HEAD(headp, newvariable, entries);
   }

   ast_channel_amaflags_set(tchan, record.amaflag);

   /* We need to store an 'application name' and 'application
    * data' on the channel for logging purposes, but the channel
    * structure only provides a place to store pointers, and it
    * expects these pointers to be pointing to data that does not
    * need to be freed. This means that the channel's destructor
    * does not attempt to free any storage that these pointers
    * point to. However, we can't provide data in that form directly for
    * these structure members. In order to ensure that these data
    * elements have a lifetime that matches the channel's
    * lifetime, we'll put them in a datastore attached to the
    * channel, and set's the channel's pointers to point into the
    * datastore.  The datastore will then be automatically destroyed
    * when the channel is destroyed.
    */

   if (!(datastore = ast_datastore_alloc(&fabricated_channel_datastore, NULL))) {
      ast_channel_unref(tchan);
      return NULL;
   }

   if (!(app_data = ast_malloc(strlen(record.application_name) + strlen(record.application_data) + 2))) {
      ast_datastore_free(datastore);
      ast_channel_unref(tchan);
      return NULL;
   }

   ast_channel_appl_set(tchan, strcpy(app_data, record.application_name));
   ast_channel_data_set(tchan, strcpy(app_data + strlen(record.application_name) + 1,
      record.application_data));

   datastore->data = app_data;
   ast_channel_datastore_add(tchan, datastore);

   return tchan;
}

static int cel_linkedid_ref(const char *linkedid)
{
   RAII_VAR(struct ao2_container *, linkedids, ao2_global_obj_ref(cel_linkedids), ao2_cleanup);
   struct cel_linkedid *lid;

   if (ast_strlen_zero(linkedid)) {
      ast_log(LOG_ERROR, "The linkedid should never be empty\n");
      return -1;
   }
   if (!linkedids) {
      /* The CEL module is shutdown.  Abort. */
      return -1;
   }

   ao2_lock(linkedids);
   lid = ao2_find(linkedids, (void *) linkedid, OBJ_SEARCH_KEY);
   if (!lid) {
      /*
       * Changes to the lid->count member are protected by the
       * container lock so the lid object does not need its own lock.
       */
      lid = ao2_alloc_options(sizeof(*lid) + strlen(linkedid) + 1, NULL,
         AO2_ALLOC_OPT_LOCK_NOLOCK);
      if (!lid) {
         ao2_unlock(linkedids);
         return -1;
      }
      strcpy(lid->id, linkedid);/* Safe */

      ao2_link(linkedids, lid);
   }
   ++lid->count;
   ao2_unlock(linkedids);
   ao2_ref(lid, -1);

   return 0;
}

int ast_cel_fill_record(const struct ast_event *e, struct ast_cel_event_record *r)
{
   if (r->version != AST_CEL_EVENT_RECORD_VERSION) {
      ast_log(LOG_ERROR, "Module ABI mismatch for ast_cel_event_record.  "
            "Please ensure all modules were compiled for "
            "this version of Asterisk.\n");
      return -1;
   }

   r->event_type = ast_event_get_ie_uint(e, AST_EVENT_IE_CEL_EVENT_TYPE);

   r->event_time.tv_sec = ast_event_get_ie_uint(e, AST_EVENT_IE_CEL_EVENT_TIME);
   r->event_time.tv_usec = ast_event_get_ie_uint(e, AST_EVENT_IE_CEL_EVENT_TIME_USEC);

   r->event_name = ast_cel_get_type_name(r->event_type);
   if (r->event_type == AST_CEL_USER_DEFINED) {
      r->user_defined_name = ast_event_get_ie_str(e, AST_EVENT_IE_CEL_USEREVENT_NAME);
   } else {
      r->user_defined_name = "";
   }

   r->caller_id_name   = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_CIDNAME), "");
   r->caller_id_num    = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_CIDNUM), "");
   r->caller_id_ani    = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_CIDANI), "");
   r->caller_id_rdnis  = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_CIDRDNIS), "");
   r->caller_id_dnid   = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_CIDDNID), "");
   r->extension        = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_EXTEN), "");
   r->context          = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_CONTEXT), "");
   r->channel_name     = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_CHANNAME), "");
   r->application_name = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_APPNAME), "");
   r->application_data = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_APPDATA), "");
   r->account_code     = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_ACCTCODE), "");
   r->peer_account     = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_PEERACCT), "");
   r->unique_id        = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_UNIQUEID), "");
   r->linked_id        = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_LINKEDID), "");
   r->amaflag          = ast_event_get_ie_uint(e, AST_EVENT_IE_CEL_AMAFLAGS);
   r->user_field       = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_USERFIELD), "");
   r->peer             = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_PEER), "");
   r->extra            = S_OR(ast_event_get_ie_str(e, AST_EVENT_IE_CEL_EXTRA), "");

   return 0;
}

/*! \brief Typedef for callbacks that get called on channel snapshot updates */
typedef void (*cel_channel_snapshot_monitor)(
   struct ast_channel_snapshot *old_snapshot,
   struct ast_channel_snapshot *new_snapshot,
   const struct timeval *event_time);

static struct cel_dialstatus *get_dialstatus(const char *uniqueid)
{
   struct ao2_container *dial_statuses = ao2_global_obj_ref(cel_dialstatus_store);
   struct cel_dialstatus *dialstatus = NULL;

   if (dial_statuses) {
      dialstatus = ao2_find(dial_statuses, uniqueid, OBJ_SEARCH_KEY | OBJ_UNLINK);
      ao2_ref(dial_statuses, -1);
   }
   return dialstatus;
}

static const char *get_blob_variable(struct ast_multi_channel_blob *blob, const char *varname)
{
   struct ast_json *json = ast_multi_channel_blob_get_json(blob);
   if (!json) {
      return NULL;
   }

   json = ast_json_object_get(json, varname);
   if (!json) {
      return NULL;
   }

   return ast_json_string_get(json);
}

/*! \brief Handle channel state changes */
static void cel_channel_state_change(
   struct ast_channel_snapshot *old_snapshot,
   struct ast_channel_snapshot *new_snapshot,
   const struct timeval *event_time)
{
   int is_hungup, was_hungup;

   if (!old_snapshot) {
      cel_report_event(new_snapshot, AST_CEL_CHANNEL_START, event_time, NULL, NULL, NULL);
      return;
   }

   was_hungup = ast_test_flag(&old_snapshot->flags, AST_FLAG_DEAD) ? 1 : 0;
   is_hungup = ast_test_flag(&new_snapshot->flags, AST_FLAG_DEAD) ? 1 : 0;

   if (!was_hungup && is_hungup) {
      struct ast_json *extra;
      struct cel_dialstatus *dialstatus = get_dialstatus(new_snapshot->base->uniqueid);

      extra = ast_json_pack("{s: i, s: s, s: s}",
         "hangupcause", new_snapshot->hangup->cause,
         "hangupsource", new_snapshot->hangup->source,
         "dialstatus", dialstatus ? dialstatus->dialstatus : "");
      cel_report_event(new_snapshot, AST_CEL_HANGUP, event_time, NULL, extra, NULL);
      ast_json_unref(extra);
      ao2_cleanup(dialstatus);

      cel_report_event(new_snapshot, AST_CEL_CHANNEL_END, event_time, NULL, NULL, NULL);
      if (ast_cel_track_event(AST_CEL_LINKEDID_END)) {
         check_retire_linkedid(new_snapshot, event_time);
      }
      return;
   }

   if (old_snapshot->state != new_snapshot->state && new_snapshot->state == AST_STATE_UP) {
      cel_report_event(new_snapshot, AST_CEL_ANSWER, event_time, NULL, NULL, NULL);
      return;
   }
}

static void cel_channel_linkedid_change(
   struct ast_channel_snapshot *old_snapshot,
   struct ast_channel_snapshot *new_snapshot,
   const struct timeval *event_time)
{
   if (!old_snapshot) {
      return;
   }

   ast_assert(!ast_strlen_zero(new_snapshot->peer->linkedid));
   ast_assert(!ast_strlen_zero(old_snapshot->peer->linkedid));

   if (ast_cel_track_event(AST_CEL_LINKEDID_END)
      && strcmp(old_snapshot->peer->linkedid, new_snapshot->peer->linkedid)) {
      cel_linkedid_ref(new_snapshot->peer->linkedid);
      check_retire_linkedid(old_snapshot, event_time);
   }
}

static void cel_channel_app_change(
   struct ast_channel_snapshot *old_snapshot,
   struct ast_channel_snapshot *new_snapshot,
   const struct timeval *event_time)
{
   if (old_snapshot && !strcmp(old_snapshot->dialplan->appl, new_snapshot->dialplan->appl)) {
      return;
   }

   /* old snapshot has an application, end it */
   if (old_snapshot && !ast_strlen_zero(old_snapshot->dialplan->appl)) {
      cel_report_event(old_snapshot, AST_CEL_APP_END, event_time, NULL, NULL, NULL);
   }

   /* new snapshot has an application, start it */
   if (!ast_strlen_zero(new_snapshot->dialplan->appl)) {
      cel_report_event(new_snapshot, AST_CEL_APP_START, event_time, NULL, NULL, NULL);
   }
}

/* \brief Handlers for channel snapshot changes.
 * \note Order of the handlers matters. Application changes must come before state
 * changes to ensure that hangup notifications occur after application changes.
 * Linkedid checking should always come last.
 */
cel_channel_snapshot_monitor cel_channel_monitors[] = {
   cel_channel_app_change,
   cel_channel_state_change,
   cel_channel_linkedid_change,
};

static int cel_filter_channel_snapshot(struct ast_channel_snapshot *snapshot)
{
   if (!snapshot) {
      return 0;
   }
   return snapshot->base->tech_properties & AST_CHAN_TP_INTERNAL;
}

static void cel_snapshot_update_cb(void *data, struct stasis_subscription *sub,
   struct stasis_message *message)
{
   struct ast_channel_snapshot_update *update = stasis_message_data(message);
   size_t i;

   if (cel_filter_channel_snapshot(update->old_snapshot) || cel_filter_channel_snapshot(update->new_snapshot)) {
      return;
   }

   for (i = 0; i < ARRAY_LEN(cel_channel_monitors); ++i) {
      cel_channel_monitors[i](update->old_snapshot, update->new_snapshot, stasis_message_timestamp(message));
   }
}

static struct ast_str *cel_generate_peer_str(
   struct ast_bridge_snapshot *bridge,
   struct ast_channel_snapshot *chan)
{
   struct ast_str *peer_str = ast_str_create(32);
   struct ao2_iterator i;
   char *current_chan = NULL;

   if (!peer_str) {
      return NULL;
   }

   for (i = ao2_iterator_init(bridge->channels, 0);
      (current_chan = ao2_iterator_next(&i));
      ao2_cleanup(current_chan)) {
      struct ast_channel_snapshot *current_snapshot;

      /* Don't add the channel for which this message is being generated */
      if (!strcmp(current_chan, chan->base->uniqueid)) {
         continue;
      }

      current_snapshot = ast_channel_snapshot_get_latest(current_chan);
      if (!current_snapshot) {
         continue;
      }

      ast_str_append(&peer_str, 0, "%s,", current_snapshot->base->name);
      ao2_cleanup(current_snapshot);
   }
   ao2_iterator_destroy(&i);

   /* Rip off the trailing comma */
   ast_str_truncate(peer_str, -1);

   return peer_str;
}

static void cel_bridge_enter_cb(
   void *data, struct stasis_subscription *sub,
   struct stasis_message *message)
{
   struct ast_bridge_blob *blob = stasis_message_data(message);
   struct ast_bridge_snapshot *snapshot = blob->bridge;
   struct ast_channel_snapshot *chan_snapshot = blob->channel;
   RAII_VAR(struct ast_json *, extra, NULL, ast_json_unref);
   RAII_VAR(struct ast_str *, peer_str, NULL, ast_free);

   if (cel_filter_channel_snapshot(chan_snapshot)) {
      return;
   }

   extra = ast_json_pack("{s: s, s: s}",
      "bridge_id", snapshot->uniqueid,
      "bridge_technology", snapshot->technology);
   if (!extra) {
      return;
   }

   peer_str = cel_generate_peer_str(snapshot, chan_snapshot);
   if (!peer_str) {
      return;
   }

   cel_report_event(chan_snapshot, AST_CEL_BRIDGE_ENTER, stasis_message_timestamp(message),
      NULL, extra, ast_str_buffer(peer_str));
}

static void cel_bridge_leave_cb(
   void *data, struct stasis_subscription *sub,
   struct stasis_message *message)
{
   struct ast_bridge_blob *blob = stasis_message_data(message);
   struct ast_bridge_snapshot *snapshot = blob->bridge;
   struct ast_channel_snapshot *chan_snapshot = blob->channel;
   RAII_VAR(struct ast_json *, extra, NULL, ast_json_unref);
   RAII_VAR(struct ast_str *, peer_str, NULL, ast_free);

   if (cel_filter_channel_snapshot(chan_snapshot)) {
      return;
   }

   extra = ast_json_pack("{s: s, s: s}",
      "bridge_id", snapshot->uniqueid,
      "bridge_technology", snapshot->technology);
   if (!extra) {
      return;
   }

   peer_str = cel_generate_peer_str(snapshot, chan_snapshot);
   if (!peer_str) {
      return;
   }

   cel_report_event(chan_snapshot, AST_CEL_BRIDGE_EXIT, stasis_message_timestamp(message),
      NULL, extra, ast_str_buffer(peer_str));
}

static void cel_parking_cb(
   void *data, struct stasis_subscription *sub,
   struct stasis_message *message)
{
   struct ast_parked_call_payload *parked_payload = stasis_message_data(message);
   RAII_VAR(struct ast_json *, extra, NULL, ast_json_unref);
   const char *reason = NULL;

   switch (parked_payload->event_type) {
   case PARKED_CALL:
      extra = ast_json_pack("{s: s, s: s}",
         "parker_dial_string", parked_payload->parker_dial_string,
         "parking_lot", parked_payload->parkinglot);
      if (extra) {
         cel_report_event(parked_payload->parkee, AST_CEL_PARK_START, stasis_message_timestamp(message),
            NULL, extra, NULL);
      }
      return;
   case PARKED_CALL_TIMEOUT:
      reason = "ParkedCallTimeOut";
      break;
   case PARKED_CALL_GIVEUP:
      reason = "ParkedCallGiveUp";
      break;
   case PARKED_CALL_UNPARKED:
      reason = "ParkedCallUnparked";
      break;
   case PARKED_CALL_FAILED:
      reason = "ParkedCallFailed";
      break;
   case PARKED_CALL_SWAP:
      reason = "ParkedCallSwap";
      break;
   }

   if (parked_payload->retriever) {
      extra = ast_json_pack("{s: s, s: s}",
         "reason", reason ?: "",
         "retriever", parked_payload->retriever->base->name);
   } else {
      extra = ast_json_pack("{s: s}", "reason", reason ?: "");
   }

   if (extra) {
      cel_report_event(parked_payload->parkee, AST_CEL_PARK_END, stasis_message_timestamp(message),
         NULL, extra, NULL);
   }
}

static void save_dialstatus(struct ast_multi_channel_blob *blob, struct ast_channel_snapshot *snapshot)
{
   struct ao2_container *dial_statuses = ao2_global_obj_ref(cel_dialstatus_store);
   const char *dialstatus_string = get_blob_variable(blob, "dialstatus");
   struct cel_dialstatus *dialstatus;
   size_t dialstatus_string_len;

   if (!dial_statuses || ast_strlen_zero(dialstatus_string)) {
      ao2_cleanup(dial_statuses);
      return;
   }

   dialstatus = ao2_find(dial_statuses, snapshot->base->uniqueid, OBJ_SEARCH_KEY);
   if (dialstatus) {
      if (!strcasecmp(dialstatus_string, "ANSWER") && strcasecmp(dialstatus->dialstatus, "ANSWER")) {
         /* In the case of an answer after we already have a dial status we give
          * priority to the answer since the call was, well, answered. In the case of
          * failure dial status results we simply let the first failure be the status.
          */
         ao2_unlink(dial_statuses, dialstatus);
         ao2_ref(dialstatus, -1);
      } else {
         ao2_ref(dialstatus, -1);
         ao2_ref(dial_statuses, -1);
         return;
      }
   }

   dialstatus_string_len = strlen(dialstatus_string) + 1;
   dialstatus = ao2_alloc_options(sizeof(*dialstatus) + dialstatus_string_len, NULL,
      AO2_ALLOC_OPT_LOCK_NOLOCK);
   if (!dialstatus) {
      ao2_ref(dial_statuses, -1);
      return;
   }

   ast_copy_string(dialstatus->uniqueid, snapshot->base->uniqueid, sizeof(dialstatus->uniqueid));
   ast_copy_string(dialstatus->dialstatus, dialstatus_string, dialstatus_string_len);

   ao2_link(dial_statuses, dialstatus);
   ao2_ref(dialstatus, -1);
   ao2_ref(dial_statuses, -1);
}

static int is_valid_dialstatus(struct ast_multi_channel_blob *blob)
{
   const char *dialstatus = get_blob_variable(blob, "dialstatus");
   int res = 0;

   if (ast_strlen_zero(dialstatus)) {
      res = 0;
   } else if (!strcasecmp(dialstatus, "CHANUNAVAIL")) {
      res = 1;
   } else if (!strcasecmp(dialstatus, "CONGESTION")) {
      res = 1;
   } else if (!strcasecmp(dialstatus, "NOANSWER")) {
      res = 1;
   } else if (!strcasecmp(dialstatus, "BUSY")) {
      res = 1;
   } else if (!strcasecmp(dialstatus, "ANSWER")) {
      res = 1;
   } else if (!strcasecmp(dialstatus, "CANCEL")) {
      res = 1;
   } else if (!strcasecmp(dialstatus, "DONTCALL")) {
      res = 1;
   } else if (!strcasecmp(dialstatus, "TORTURE")) {
      res = 1;
   } else if (!strcasecmp(dialstatus, "INVALIDARGS")) {
      res = 1;
   }
   return res;
}

static void cel_dial_cb(void *data, struct stasis_subscription *sub,
   struct stasis_message *message)
{
   struct ast_multi_channel_blob *blob = stasis_message_data(message);
   struct ast_channel_snapshot *snapshot;

   snapshot = ast_multi_channel_blob_get_channel(blob, "caller");
   if (!snapshot || cel_filter_channel_snapshot(snapshot)) {
      return;
   }

   if (!ast_strlen_zero(get_blob_variable(blob, "forward"))) {
      struct ast_json *extra;

      extra = ast_json_pack("{s: s}", "forward", get_blob_variable(blob, "forward"));
      if (extra) {
         cel_report_event(snapshot, AST_CEL_FORWARD, stasis_message_timestamp(message),
            NULL, extra, NULL);
         ast_json_unref(extra);
      }
   }

   if (is_valid_dialstatus(blob)) {
      save_dialstatus(blob, snapshot);
   }
}

static void cel_generic_cb(
   void *data, struct stasis_subscription *sub,
   struct stasis_message *message)
{
   struct ast_channel_blob *obj = stasis_message_data(message);
   int event_type = ast_json_integer_get(ast_json_object_get(obj->blob, "event_type"));
   struct ast_json *event_details = ast_json_object_get(obj->blob, "event_details");

   switch (event_type) {
   case AST_CEL_USER_DEFINED:
      {
         const char *event = ast_json_string_get(ast_json_object_get(event_details, "event"));
         struct ast_json *extra = ast_json_object_get(event_details, "extra");
         cel_report_event(obj->snapshot, event_type, stasis_message_timestamp(message),
            event, extra, NULL);
         break;
      }
   default:
      ast_log(LOG_ERROR, "Unhandled %s event blob\n", ast_cel_get_type_name(event_type));
      break;
   }
}

static void cel_blind_transfer_cb(
   void *data, struct stasis_subscription *sub,
   struct stasis_message *message)
{
   struct ast_blind_transfer_message *transfer_msg = stasis_message_data(message);
   struct ast_channel_snapshot *chan_snapshot = transfer_msg->transferer;
   struct ast_bridge_snapshot *bridge_snapshot = transfer_msg->bridge;
   struct ast_json *extra;

   if (transfer_msg->result != AST_BRIDGE_TRANSFER_SUCCESS) {
      return;
   }

   extra = ast_json_pack("{s: s, s: s, s: s, s: s, s: s}",
      "extension", transfer_msg->exten,
      "context", transfer_msg->context,
      "bridge_id", bridge_snapshot->uniqueid,
      "transferee_channel_name", transfer_msg->transferee ? transfer_msg->transferee->base->name : "N/A",
      "transferee_channel_uniqueid", transfer_msg->transferee ? transfer_msg->transferee->base->uniqueid  : "N/A");
   if (extra) {
      cel_report_event(chan_snapshot, AST_CEL_BLINDTRANSFER, stasis_message_timestamp(message),
         NULL, extra, NULL);
      ast_json_unref(extra);
   }
}

static void cel_attended_transfer_cb(
   void *data, struct stasis_subscription *sub,
   struct stasis_message *message)
{
   struct ast_attended_transfer_message *xfer = stasis_message_data(message);
   struct ast_json *extra = NULL;
   struct ast_bridge_snapshot *bridge1, *bridge2;
   struct ast_channel_snapshot *channel1, *channel2;

   /* Make sure bridge1 is always non-NULL */
   if (!xfer->to_transferee.bridge_snapshot) {
      bridge1 = xfer->to_transfer_target.bridge_snapshot;
      bridge2 = xfer->to_transferee.bridge_snapshot;
      channel1 = xfer->to_transfer_target.channel_snapshot;
      channel2 = xfer->to_transferee.channel_snapshot;
   } else {
      bridge1 = xfer->to_transferee.bridge_snapshot;
      bridge2 = xfer->to_transfer_target.bridge_snapshot;
      channel1 = xfer->to_transferee.channel_snapshot;
      channel2 = xfer->to_transfer_target.channel_snapshot;
   }

   switch (xfer->dest_type) {
   case AST_ATTENDED_TRANSFER_DEST_FAIL:
      return;
      /* handle these three the same */
   case AST_ATTENDED_TRANSFER_DEST_BRIDGE_MERGE:
   case AST_ATTENDED_TRANSFER_DEST_LINK:
   case AST_ATTENDED_TRANSFER_DEST_THREEWAY:
      extra = ast_json_pack("{s: s, s: s, s: s, s: s, s: s, s: s, s: s, s: s}",
         "bridge1_id", bridge1->uniqueid,
         "channel2_name", channel2->base->name,
         "channel2_uniqueid", channel2->base->uniqueid,
         "bridge2_id", bridge2->uniqueid,
         "transferee_channel_name", xfer->transferee ? xfer->transferee->base->name : "N/A",
         "transferee_channel_uniqueid", xfer->transferee ? xfer->transferee->base->uniqueid : "N/A",
         "transfer_target_channel_name", xfer->target ? xfer->target->base->name : "N/A",
         "transfer_target_channel_uniqueid", xfer->target ? xfer->target->base->uniqueid : "N/A");
      if (!extra) {
         return;
      }
      break;
   case AST_ATTENDED_TRANSFER_DEST_APP:
   case AST_ATTENDED_TRANSFER_DEST_LOCAL_APP:
      extra = ast_json_pack("{s: s, s: s, s: s, s: s, s: s, s: s, s: s, s: s}",
         "bridge1_id", bridge1->uniqueid,
         "channel2_name", channel2->base->name,
         "channel2_uniqueid", channel2->base->uniqueid,
         "app", xfer->dest.app,
         "transferee_channel_name", xfer->transferee ? xfer->transferee->base->name : "N/A",
         "transferee_channel_uniqueid", xfer->transferee ? xfer->transferee->base->uniqueid : "N/A",
         "transfer_target_channel_name", xfer->target ? xfer->target->base->name : "N/A",
         "transfer_target_channel_uniqueid", xfer->target ? xfer->target->base->uniqueid : "N/A");
      if (!extra) {
         return;
      }
      break;
   }
   cel_report_event(channel1, AST_CEL_ATTENDEDTRANSFER, stasis_message_timestamp(message),
      NULL, extra, NULL);
   ast_json_unref(extra);
}

static void cel_pickup_cb(
   void *data, struct stasis_subscription *sub,
   struct stasis_message *message)
{
   struct ast_multi_channel_blob *obj = stasis_message_data(message);
   struct ast_channel_snapshot *channel = ast_multi_channel_blob_get_channel(obj, "channel");
   struct ast_channel_snapshot *target = ast_multi_channel_blob_get_channel(obj, "target");
   struct ast_json *extra;

   if (!channel || !target) {
      return;
   }

   extra = ast_json_pack("{s: s, s: s}",
      "pickup_channel", channel->base->name,
      "pickup_channel_uniqueid", channel->base->uniqueid);
   if (!extra) {
      return;
   }

   cel_report_event(target, AST_CEL_PICKUP, stasis_message_timestamp(message), NULL, extra, NULL);
   ast_json_unref(extra);
}

static void cel_local_cb(
   void *data, struct stasis_subscription *sub,
   struct stasis_message *message)
{
   struct ast_multi_channel_blob *obj = stasis_message_data(message);
   struct ast_channel_snapshot *localone = ast_multi_channel_blob_get_channel(obj, "1");
   struct ast_channel_snapshot *localtwo = ast_multi_channel_blob_get_channel(obj, "2");
   struct ast_json *extra;

   if (!localone || !localtwo) {
      return;
   }

   extra = ast_json_pack("{s: s, s: s}",
      "local_two", localtwo->base->name,
      "local_two_uniqueid", localtwo->base->uniqueid);
   if (!extra) {
      return;
   }

   cel_report_event(localone, AST_CEL_LOCAL_OPTIMIZE, stasis_message_timestamp(message), NULL, extra, NULL);
   ast_json_unref(extra);
}

static void destroy_routes(void)
{
   stasis_message_router_unsubscribe_and_join(cel_state_router);
   cel_state_router = NULL;
}

static void destroy_subscriptions(void)
{
   ao2_cleanup(cel_aggregation_topic);
   cel_aggregation_topic = NULL;
   ao2_cleanup(cel_topic);
   cel_topic = NULL;

   cel_channel_forwarder = stasis_forward_cancel(cel_channel_forwarder);
   cel_bridge_forwarder = stasis_forward_cancel(cel_bridge_forwarder);
   cel_parking_forwarder = stasis_forward_cancel(cel_parking_forwarder);
   cel_cel_forwarder = stasis_forward_cancel(cel_cel_forwarder);
}

static int unload_module(void)
{
   destroy_routes();
   destroy_subscriptions();
   STASIS_MESSAGE_TYPE_CLEANUP(cel_generic_type);

   ast_cli_unregister(&cli_status);
   aco_info_destroy(&cel_cfg_info);
   ao2_global_obj_release(cel_configs);
   ao2_global_obj_release(cel_dialstatus_store);
   ao2_global_obj_release(cel_linkedids);
   ao2_global_obj_release(cel_backends);

   return 0;
}

/*!
 * \brief Create the Stasis subscriptions for CEL
 */
static int create_subscriptions(void)
{
   cel_aggregation_topic = stasis_topic_create("cel:aggregator");
   if (!cel_aggregation_topic) {
      return -1;
   }

   cel_topic = stasis_topic_create("cel:misc");
   if (!cel_topic) {
      return -1;
   }

   cel_channel_forwarder = stasis_forward_all(
      ast_channel_topic_all(),
      cel_aggregation_topic);
   if (!cel_channel_forwarder) {
      return -1;
   }

   cel_bridge_forwarder = stasis_forward_all(
      ast_bridge_topic_all(),
      cel_aggregation_topic);
   if (!cel_bridge_forwarder) {
      return -1;
   }

   cel_parking_forwarder = stasis_forward_all(
      ast_parking_topic(),
      cel_aggregation_topic);
   if (!cel_parking_forwarder) {
      return -1;
   }

   cel_cel_forwarder = stasis_forward_all(
      ast_cel_topic(),
      cel_aggregation_topic);
   if (!cel_cel_forwarder) {
      return -1;
   }

   return 0;
}

/*!
 * \brief Create the Stasis message router and routes for CEL
 */
static int create_routes(void)
{
   int ret = 0;

   cel_state_router = stasis_message_router_create(cel_aggregation_topic);
   if (!cel_state_router) {
      return -1;
   }
   stasis_message_router_set_congestion_limits(cel_state_router, -1,
      6 * AST_TASKPROCESSOR_HIGH_WATER_LEVEL);

   ret |= stasis_message_router_add(cel_state_router,
      ast_channel_snapshot_type(),
      cel_snapshot_update_cb,
      NULL);

   ret |= stasis_message_router_add(cel_state_router,
      ast_channel_dial_type(),
      cel_dial_cb,
      NULL);

   ret |= stasis_message_router_add(cel_state_router,
      ast_channel_entered_bridge_type(),
      cel_bridge_enter_cb,
      NULL);

   ret |= stasis_message_router_add(cel_state_router,
      ast_channel_left_bridge_type(),
      cel_bridge_leave_cb,
      NULL);

   ret |= stasis_message_router_add(cel_state_router,
      ast_parked_call_type(),
      cel_parking_cb,
      NULL);

   ret |= stasis_message_router_add(cel_state_router,
      cel_generic_type(),
      cel_generic_cb,
      NULL);

   ret |= stasis_message_router_add(cel_state_router,
      ast_blind_transfer_type(),
      cel_blind_transfer_cb,
      NULL);

   ret |= stasis_message_router_add(cel_state_router,
      ast_attended_transfer_type(),
      cel_attended_transfer_cb,
      NULL);

   ret |= stasis_message_router_add(cel_state_router,
      ast_call_pickup_type(),
      cel_pickup_cb,
      NULL);

   ret |= stasis_message_router_add(cel_state_router,
      ast_local_optimization_end_type(),
      cel_local_cb,
      NULL);

   if (ret) {
      ast_log(AST_LOG_ERROR, "Failed to register for Stasis messages\n");
   }

   return ret;
}

AO2_STRING_FIELD_HASH_FN(cel_linkedid, id)
AO2_STRING_FIELD_CMP_FN(cel_linkedid, id)

static int load_module(void)
{
   struct ao2_container *container;

   container = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0,
      NUM_APP_BUCKETS, cel_linkedid_hash_fn, NULL, cel_linkedid_cmp_fn);
   ao2_global_obj_replace_unref(cel_linkedids, container);
   ao2_cleanup(container);
   if (!container) {
      return AST_MODULE_LOAD_FAILURE;
   }

   container = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0,
      NUM_DIALSTATUS_BUCKETS, cel_dialstatus_hash_fn, NULL, cel_dialstatus_cmp_fn);
   ao2_global_obj_replace_unref(cel_dialstatus_store, container);
   ao2_cleanup(container);
   if (!container) {
      return AST_MODULE_LOAD_FAILURE;
   }

   if (STASIS_MESSAGE_TYPE_INIT(cel_generic_type)) {
      return AST_MODULE_LOAD_FAILURE;
   }

   if (ast_cli_register(&cli_status)) {
      return AST_MODULE_LOAD_FAILURE;
   }

   container = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0, BACKEND_BUCKETS,
      cel_backend_hash_fn, NULL, cel_backend_cmp_fn);
   ao2_global_obj_replace_unref(cel_backends, container);
   ao2_cleanup(container);
   if (!container) {
      return AST_MODULE_LOAD_FAILURE;
   }

   if (aco_info_init(&cel_cfg_info)) {
      return AST_MODULE_LOAD_FAILURE;
   }

   aco_option_register(&cel_cfg_info, "enable", ACO_EXACT, general_options, "no", OPT_BOOL_T, 1, FLDSET(struct ast_cel_general_config, enable));
   aco_option_register(&cel_cfg_info, "dateformat", ACO_EXACT, general_options, "", OPT_STRINGFIELD_T, 0, STRFLDSET(struct ast_cel_general_config, date_format));
   aco_option_register_custom(&cel_cfg_info, "apps", ACO_EXACT, general_options, "", apps_handler, 0);
   aco_option_register_custom(&cel_cfg_info, "events", ACO_EXACT, general_options, "", events_handler, 0);

   if (aco_process_config(&cel_cfg_info, 0)) {
      struct cel_config *cel_cfg = cel_config_alloc();

      if (!cel_cfg) {
         return AST_MODULE_LOAD_FAILURE;
      }

      /* We couldn't process the configuration so create a default config. */
      if (!aco_set_defaults(&general_option, "general", cel_cfg->general)) {
         ast_log(LOG_NOTICE, "Failed to process CEL configuration; using defaults\n");
         ao2_global_obj_replace_unref(cel_configs, cel_cfg);
      }
      ao2_ref(cel_cfg, -1);
   }

   if (create_subscriptions()) {
      return AST_MODULE_LOAD_FAILURE;
   }

   if (ast_cel_check_enabled() && create_routes()) {
      return AST_MODULE_LOAD_FAILURE;
   }

   return AST_MODULE_LOAD_SUCCESS;
}

static int reload_module(void)
{
   unsigned int was_enabled = ast_cel_check_enabled();
   unsigned int is_enabled;

   if (aco_process_config(&cel_cfg_info, 1) == ACO_PROCESS_ERROR) {
      return -1;
   }

   is_enabled = ast_cel_check_enabled();

   if (!was_enabled && is_enabled) {
      if (create_routes()) {
         return -1;
      }
   } else if (was_enabled && !is_enabled) {
      destroy_routes();
   }

   ast_verb(3, "CEL logging %sabled.\n", is_enabled ? "en" : "dis");

   return 0;
}

void ast_cel_publish_event(struct ast_channel *chan,
   enum ast_cel_event_type event_type,
   struct ast_json *blob)
{
   struct ast_json *cel_blob;
   struct stasis_message *message;

   cel_blob = ast_json_pack("{s: i, s: o}",
      "event_type", event_type,
      "event_details", ast_json_ref(blob));

   message = ast_channel_blob_create_from_cache(ast_channel_uniqueid(chan), cel_generic_type(), cel_blob);
   if (message) {
      stasis_publish(ast_cel_topic(), message);
   }
   ao2_cleanup(message);
   ast_json_unref(cel_blob);
}

struct stasis_topic *ast_cel_topic(void)
{
   return cel_topic;
}

struct ast_cel_general_config *ast_cel_get_config(void)
{
   RAII_VAR(struct cel_config *, mod_cfg, ao2_global_obj_ref(cel_configs), ao2_cleanup);

   if (!mod_cfg || !mod_cfg->general) {
      return NULL;
   }

   ao2_ref(mod_cfg->general, +1);
   return mod_cfg->general;
}

void ast_cel_set_config(struct ast_cel_general_config *config)
{
   int was_enabled;
   int is_enabled;
   struct ast_cel_general_config *cleanup_config;
   struct cel_config *mod_cfg = ao2_global_obj_ref(cel_configs);

   if (mod_cfg) {
      was_enabled = ast_cel_check_enabled();

      cleanup_config = mod_cfg->general;
      ao2_bump(config);
      mod_cfg->general = config;
      ao2_cleanup(cleanup_config);

      is_enabled = ast_cel_check_enabled();
      if (!was_enabled && is_enabled) {
         create_routes();
      } else if (was_enabled && !is_enabled) {
         destroy_routes();
      }

      ao2_ref(mod_cfg, -1);
   }
}

int ast_cel_backend_unregister(const char *name)
{
   struct ao2_container *backends = ao2_global_obj_ref(cel_backends);

   if (backends) {
      ao2_find(backends, name, OBJ_SEARCH_KEY | OBJ_NODATA | OBJ_UNLINK);
      ao2_ref(backends, -1);
   }

   return 0;
}

int ast_cel_backend_register(const char *name, ast_cel_backend_cb backend_callback)
{
   RAII_VAR(struct ao2_container *, backends, ao2_global_obj_ref(cel_backends), ao2_cleanup);
   struct cel_backend *backend;

   if (!backends || ast_strlen_zero(name) || !backend_callback) {
      return -1;
   }

   /* The backend object is immutable so it doesn't need a lock of its own. */
   backend = ao2_alloc_options(sizeof(*backend) + 1 + strlen(name), NULL,
      AO2_ALLOC_OPT_LOCK_NOLOCK);
   if (!backend) {
      return -1;
   }
   strcpy(backend->name, name);/* Safe */
   backend->callback = backend_callback;

   ao2_link(backends, backend);
   ao2_ref(backend, -1);
   return 0;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS | AST_MODFLAG_LOAD_ORDER, "CEL Engine",
   .support_level = AST_MODULE_SUPPORT_CORE,
   .load = load_module,
   .unload = unload_module,
   .reload = reload_module,
   .load_pri = AST_MODPRI_CORE,
   .requires = "extconfig",
);