res_pjsip_exten_state.c

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

/*** MODULEINFO
   <depend>pjproject</depend>
   <depend>res_pjsip</depend>
   <depend>res_pjsip_pubsub</depend>
   <depend>res_pjsip_outbound_publish</depend>
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include <regex.h>

#include <pjsip.h>
#include <pjsip_simple.h>
#include <pjlib.h>

#include "asterisk/res_pjsip.h"
#include "asterisk/res_pjsip_outbound_publish.h"
#include "asterisk/res_pjsip_pubsub.h"
#include "asterisk/res_pjsip_body_generator_types.h"
#include "asterisk/module.h"
#include "asterisk/logger.h"
#include "asterisk/astobj2.h"
#include "asterisk/sorcery.h"
#include "asterisk/app.h"
#include "asterisk/taskprocessor.h"

#define BODY_SIZE 1024
#define EVENT_TYPE_SIZE 50

/*!
 * \brief The number of buckets to use for storing publishers
 */
#define PUBLISHER_BUCKETS 31

/*!
 * \brief Container of active outbound extension state publishers
 */
static struct ao2_container *publishers;

/*! Serializer for outbound extension state publishing. */
static struct ast_taskprocessor *publish_exten_state_serializer;

/*!
 * \brief A subscription for extension state
 *
 * This structure acts as the owner for the underlying SIP subscription. It
 * also keeps a pointer to an associated "provider" so when a state changes
 * a notify data creator is quickly accessible.
 */
struct exten_state_subscription {
   /*! Watcher id when registering for extension state changes */
   int id;
   /*! The SIP subscription */
   struct ast_sip_subscription *sip_sub;
   /*! The serializer to use for notifications */
   struct ast_taskprocessor *serializer;
   /*! Context in which subscription looks for updates */
   char context[AST_MAX_CONTEXT];
   /*! Extension within the context to receive updates from */
   char exten[AST_MAX_EXTENSION];
   /*! The subscription's user agent */
   char *user_agent;
   /*! The last known extension state */
   enum ast_extension_states last_exten_state;
   /*! The last known presence state */
   enum ast_presence_state last_presence_state;
};

/*!
 * \brief An extension state publisher
 *
 */
struct exten_state_publisher {
   /*! Regular expression for context filtering */
   regex_t context_regex;
   /*! Regular expression for extension filtering */
   regex_t exten_regex;
   /*! Publish client to use for sending publish messages */
   struct ast_sip_outbound_publish_client *client;
   /*! Datastores container to hold persistent information */
   struct ao2_container *datastores;
   /*! Whether context filtering is active */
   unsigned int context_filter;
   /*! Whether extension filtering is active */
   unsigned int exten_filter;
   /*! The body type to use for this publisher - stored after the name */
   char *body_type;
   /*! The body subtype to use for this publisher - stored after the body type */
   char *body_subtype;
   /*! The name of this publisher */
   char name[0];
};

#define DEFAULT_PRESENCE_BODY "application/pidf+xml"
#define DEFAULT_DIALOG_BODY "application/dialog-info+xml"

static void subscription_shutdown(struct ast_sip_subscription *sub);
static int new_subscribe(struct ast_sip_endpoint *endpoint, const char *resource);
static int subscription_established(struct ast_sip_subscription *sub);
static void *get_notify_data(struct ast_sip_subscription *sub);
static void to_ami(struct ast_sip_subscription *sub,
         struct ast_str **buf);
static int publisher_start(struct ast_sip_outbound_publish *configuration,
            struct ast_sip_outbound_publish_client *client);
static int publisher_stop(struct ast_sip_outbound_publish_client *client);

struct ast_sip_notifier presence_notifier = {
   .default_accept = DEFAULT_PRESENCE_BODY,
   .new_subscribe = new_subscribe,
   .subscription_established = subscription_established,
   .get_notify_data = get_notify_data,
};

struct ast_sip_notifier dialog_notifier = {
   .default_accept = DEFAULT_DIALOG_BODY,
   .new_subscribe = new_subscribe,
   .subscription_established = subscription_established,
   .get_notify_data = get_notify_data,
};

struct ast_sip_subscription_handler presence_handler = {
   .event_name = "presence",
   .body_type = AST_SIP_EXTEN_STATE_DATA,
   .accept = { DEFAULT_PRESENCE_BODY, },
   .subscription_shutdown = subscription_shutdown,
   .to_ami = to_ami,
   .notifier = &presence_notifier,
};

struct ast_sip_event_publisher_handler presence_publisher = {
   .event_name = "presence",
   .start_publishing = publisher_start,
   .stop_publishing = publisher_stop,
};

struct ast_sip_subscription_handler dialog_handler = {
   .event_name = "dialog",
   .body_type = AST_SIP_EXTEN_STATE_DATA,
   .accept = { DEFAULT_DIALOG_BODY, },
   .subscription_shutdown = subscription_shutdown,
   .to_ami = to_ami,
   .notifier = &dialog_notifier,
};

struct ast_sip_event_publisher_handler dialog_publisher = {
   .event_name = "dialog",
   .start_publishing = publisher_start,
   .stop_publishing = publisher_stop,
};

static void exten_state_subscription_destructor(void *obj)
{
   struct exten_state_subscription *sub = obj;

   ast_free(sub->user_agent);
   ast_sip_subscription_destroy(sub->sip_sub);
   ast_taskprocessor_unreference(sub->serializer);
}

static char *get_user_agent(const struct ast_sip_subscription *sip_sub)
{
   size_t size;
   char *user_agent = NULL;
   pjsip_user_agent_hdr *user_agent_hdr = ast_sip_subscription_get_header(
         sip_sub, "User-Agent");

   if (!user_agent_hdr) {
      return NULL;
   }

   size = pj_strlen(&user_agent_hdr->hvalue) + 1;
   user_agent = ast_malloc(size);
   ast_copy_pj_str(user_agent, &user_agent_hdr->hvalue, size);
   return ast_str_to_lower(user_agent);
}

/*!
 * \internal
 * \brief Initialize the last extension state to something outside
 * its usual states.
 */
#define INITIAL_LAST_EXTEN_STATE -3

/*!
 * \internal
 * \brief Allocates an exten_state_subscription object.
 *
 * Creates the underlying SIP subscription for the given request. First makes
 * sure that there are registered handler and provider objects available.
 */
static struct exten_state_subscription *exten_state_subscription_alloc(
      struct ast_sip_subscription *sip_sub, struct ast_sip_endpoint *endpoint)
{
   struct exten_state_subscription * exten_state_sub;

   exten_state_sub = ao2_alloc(sizeof(*exten_state_sub), exten_state_subscription_destructor);
   if (!exten_state_sub) {
      return NULL;
   }

   exten_state_sub->sip_sub = sip_sub;

   /* We keep our own reference to the serializer as there is no guarantee in state_changed
    * that the subscription tree is still valid when it is called. This can occur when
    * the subscription is terminated at around the same time as the state_changed
    * callback is invoked.
    */
   exten_state_sub->serializer = ao2_bump(ast_sip_subscription_get_serializer(sip_sub));
   exten_state_sub->last_exten_state = INITIAL_LAST_EXTEN_STATE;
   exten_state_sub->last_presence_state = AST_PRESENCE_NOT_SET;
   exten_state_sub->user_agent = get_user_agent(sip_sub);
   return exten_state_sub;
}

struct notify_task_data {
   struct ast_sip_exten_state_data exten_state_data;
   struct exten_state_subscription *exten_state_sub;
   int terminate;
};

static void notify_task_data_destructor(void *obj)
{
   struct notify_task_data *task_data = obj;

   ao2_ref(task_data->exten_state_sub, -1);
   ao2_cleanup(task_data->exten_state_data.device_state_info);
   ast_free(task_data->exten_state_data.presence_subtype);
   ast_free(task_data->exten_state_data.presence_message);
   ast_free(task_data->exten_state_data.user_agent);
}

static struct notify_task_data *alloc_notify_task_data(const char *exten,
   struct exten_state_subscription *exten_state_sub,
   struct ast_state_cb_info *info)
{
   struct notify_task_data *task_data =
      ao2_alloc(sizeof(*task_data), notify_task_data_destructor);

   if (!task_data) {
      ast_log(LOG_WARNING, "Unable to create notify task data\n");
      return NULL;
   }

   task_data->exten_state_sub = exten_state_sub;
   task_data->exten_state_sub->last_exten_state = info->exten_state;
   task_data->exten_state_sub->last_presence_state = info->presence_state;
   ao2_ref(task_data->exten_state_sub, +1);

   task_data->exten_state_data.exten = exten_state_sub->exten;
   task_data->exten_state_data.exten_state = info->exten_state;
   task_data->exten_state_data.presence_state = info->presence_state;
   task_data->exten_state_data.presence_subtype = ast_strdup(info->presence_subtype);
   task_data->exten_state_data.presence_message = ast_strdup(info->presence_message);
   task_data->exten_state_data.user_agent = ast_strdup(exten_state_sub->user_agent);
   task_data->exten_state_data.device_state_info = ao2_bump(info->device_state_info);
   task_data->exten_state_data.sub = exten_state_sub->sip_sub;
   task_data->exten_state_data.datastores = ast_sip_subscription_get_datastores(exten_state_sub->sip_sub);

   if ((info->exten_state == AST_EXTENSION_DEACTIVATED) ||
       (info->exten_state == AST_EXTENSION_REMOVED)) {
      ast_verb(2, "Watcher for hint %s %s\n", exten, info->exten_state
          == AST_EXTENSION_REMOVED ? "removed" : "deactivated");
      task_data->terminate = 1;
   }

   return task_data;
}

static int notify_task(void *obj)
{
   RAII_VAR(struct notify_task_data *, task_data, obj, ao2_cleanup);
   struct ast_sip_body_data data = {
      .body_type = AST_SIP_EXTEN_STATE_DATA,
      .body_data = &task_data->exten_state_data,
   };

   /* Terminated subscriptions are no longer associated with a valid tree, and sending
    * NOTIFY messages on a subscription which has already been terminated won't work.
    */
   if (ast_sip_subscription_is_terminated(task_data->exten_state_sub->sip_sub)) {
      return 0;
   }

   /* All access to the subscription must occur within a task executed within its serializer */
   ast_sip_subscription_get_local_uri(task_data->exten_state_sub->sip_sub,
         task_data->exten_state_data.local, sizeof(task_data->exten_state_data.local));
   ast_sip_subscription_get_remote_uri(task_data->exten_state_sub->sip_sub,
         task_data->exten_state_data.remote, sizeof(task_data->exten_state_data.remote));

   /* Pool allocation has to happen here so that we allocate within a PJLIB thread */
   task_data->exten_state_data.pool = pjsip_endpt_create_pool(ast_sip_get_pjsip_endpoint(),
         "exten_state", 1024, 1024);
   if (!task_data->exten_state_data.pool) {
      return -1;
   }

   task_data->exten_state_data.sub = task_data->exten_state_sub->sip_sub;
   task_data->exten_state_data.datastores = ast_sip_subscription_get_datastores(task_data->exten_state_sub->sip_sub);

   ast_sip_subscription_notify(task_data->exten_state_sub->sip_sub, &data,
         task_data->terminate);

   pjsip_endpt_release_pool(ast_sip_get_pjsip_endpoint(),
         task_data->exten_state_data.pool);
   return 0;
}

/*!
 * \internal
 * \brief Callback for exten/device state changes.
 *
 * Upon state change, send the appropriate notification to the subscriber.
 */
static int state_changed(const char *context, const char *exten,
   struct ast_state_cb_info *info, void *data)
{
   struct notify_task_data *task_data;
   struct exten_state_subscription *exten_state_sub = data;

   if (!(task_data = alloc_notify_task_data(exten, exten_state_sub, info))) {
      return -1;
   }

   /* safe to push this async since we copy the data from info and
      add a ref for the device state info */
   if (ast_sip_push_task(task_data->exten_state_sub->serializer, notify_task,
      task_data)) {
      ao2_cleanup(task_data);
      return -1;
   }
   return 0;
}

static void state_changed_destroy(int id, void *data)
{
   struct exten_state_subscription *exten_state_sub = data;
   ao2_cleanup(exten_state_sub);
}

static struct ast_datastore_info ds_info = { };
static const char ds_name[] = "exten state datastore";

/*!
 * \internal
 * \brief Add a datastore for exten exten_state_subscription.
 *
 * Adds the exten_state_subscription wrapper object to a datastore so it can be retrieved
 * later based upon its association with the ast_sip_subscription.
 */
static int add_datastore(struct exten_state_subscription *exten_state_sub)
{
   RAII_VAR(struct ast_datastore *, datastore,
       ast_sip_subscription_alloc_datastore(&ds_info, ds_name), ao2_cleanup);

   if (!datastore) {
      return -1;
   }

   datastore->data = exten_state_sub;
   ast_sip_subscription_add_datastore(exten_state_sub->sip_sub, datastore);
   ao2_ref(exten_state_sub, +1);
   return 0;
}

/*!
 * \internal
 * \brief Get the exten_state_subscription object associated with the given
 * ast_sip_subscription in the datastore.
 */
static struct exten_state_subscription *get_exten_state_sub(
   struct ast_sip_subscription *sub)
{
   RAII_VAR(struct ast_datastore *, datastore,
       ast_sip_subscription_get_datastore(sub, ds_name), ao2_cleanup);

   return datastore ? datastore->data : NULL;
}

static void subscription_shutdown(struct ast_sip_subscription *sub)
{
   struct exten_state_subscription *exten_state_sub = get_exten_state_sub(sub);

   if (!exten_state_sub) {
      return;
   }

   ast_extension_state_del(exten_state_sub->id, state_changed);
   ast_sip_subscription_remove_datastore(exten_state_sub->sip_sub, ds_name);
   /* remove data store reference */
   ao2_cleanup(exten_state_sub);
}

static int new_subscribe(struct ast_sip_endpoint *endpoint,
      const char *resource)
{
   const char *context = S_OR(endpoint->subscription.context, endpoint->context);

   if (!ast_exists_extension(NULL, context, resource, PRIORITY_HINT, NULL)) {
      ast_log(LOG_NOTICE, "Endpoint '%s' state subscription failed: "
         "Extension '%s' does not exist in context '%s' or has no associated hint\n",
         ast_sorcery_object_get_id(endpoint), resource, context);
      return 404;
   }

   return 200;
}

static int subscription_established(struct ast_sip_subscription *sip_sub)
{
   struct ast_sip_endpoint *endpoint = ast_sip_subscription_get_endpoint(sip_sub);
   const char *resource = ast_sip_subscription_get_resource_name(sip_sub);
   struct exten_state_subscription *exten_state_sub;

   if (!(exten_state_sub = exten_state_subscription_alloc(sip_sub, endpoint))) {
      ao2_cleanup(endpoint);
      return -1;
   }

   ast_copy_string(exten_state_sub->context,
      S_OR(endpoint->subscription.context, endpoint->context),
      sizeof(exten_state_sub->context));
   ast_copy_string(exten_state_sub->exten, resource, sizeof(exten_state_sub->exten));

   if ((exten_state_sub->id = ast_extension_state_add_destroy_extended(
           exten_state_sub->context, exten_state_sub->exten,
           state_changed, state_changed_destroy, exten_state_sub)) < 0) {
      ast_log(LOG_WARNING, "Unable to subscribe endpoint '%s' to extension '%s@%s'\n",
         ast_sorcery_object_get_id(endpoint), exten_state_sub->exten,
         exten_state_sub->context);
      ao2_cleanup(endpoint);
      ao2_cleanup(exten_state_sub);
      return -1;
   }

   /* Go ahead and cleanup the endpoint since we don't need it anymore */
   ao2_cleanup(endpoint);

   /* bump the ref since ast_extension_state_add holds a reference */
   ao2_ref(exten_state_sub, +1);

   if (add_datastore(exten_state_sub)) {
      ast_log(LOG_WARNING, "Unable to add to subscription datastore.\n");
      ao2_cleanup(exten_state_sub);
      return -1;
   }

   ao2_cleanup(exten_state_sub);
   return 0;
}

static void exten_state_data_destructor(void *obj)
{
   struct ast_sip_exten_state_data *exten_state_data = obj;

   ao2_cleanup(exten_state_data->device_state_info);
   ast_free(exten_state_data->presence_subtype);
   ast_free(exten_state_data->presence_message);
   if (exten_state_data->pool) {
      pjsip_endpt_release_pool(ast_sip_get_pjsip_endpoint(), exten_state_data->pool);
   }
}

static struct ast_sip_exten_state_data *exten_state_data_alloc(struct ast_sip_subscription *sip_sub,
      struct exten_state_subscription *exten_state_sub)
{
   struct ast_sip_exten_state_data *exten_state_data;
   char *subtype = NULL;
   char *message = NULL;
   int presence_state;

   exten_state_data = ao2_alloc(sizeof(*exten_state_data), exten_state_data_destructor);
   if (!exten_state_data) {
      return NULL;
   }

   exten_state_data->exten = exten_state_sub->exten;
   presence_state = ast_hint_presence_state(NULL, exten_state_sub->context, exten_state_sub->exten, &subtype, &message);
   if (presence_state  == -1 || presence_state == AST_PRESENCE_INVALID) {
      ao2_cleanup(exten_state_data);
      return NULL;
   }
   exten_state_data->presence_state = presence_state;
   exten_state_data->presence_subtype = subtype;
   exten_state_data->presence_message = message;
   exten_state_data->user_agent = exten_state_sub->user_agent;
   ast_sip_subscription_get_local_uri(sip_sub, exten_state_data->local,
         sizeof(exten_state_data->local));
   ast_sip_subscription_get_remote_uri(sip_sub, exten_state_data->remote,
         sizeof(exten_state_data->remote));
   exten_state_data->sub = sip_sub;
   exten_state_data->datastores = ast_sip_subscription_get_datastores(sip_sub);

   exten_state_data->exten_state = ast_extension_state_extended(
         NULL, exten_state_sub->context, exten_state_sub->exten,
         &exten_state_data->device_state_info);
   if (exten_state_data->exten_state < 0) {
      ao2_cleanup(exten_state_data);
      return NULL;
   }

   exten_state_data->pool = pjsip_endpt_create_pool(ast_sip_get_pjsip_endpoint(),
         "exten_state", 1024, 1024);
   if (!exten_state_data->pool) {
      ao2_cleanup(exten_state_data);
      return NULL;
   }

   return exten_state_data;
}

static void *get_notify_data(struct ast_sip_subscription *sub)
{
   struct exten_state_subscription *exten_state_sub;

   exten_state_sub = get_exten_state_sub(sub);
   if (!exten_state_sub) {
      return NULL;
   }

   return exten_state_data_alloc(sub, exten_state_sub);
}

static void to_ami(struct ast_sip_subscription *sub,
         struct ast_str **buf)
{
   struct exten_state_subscription *exten_state_sub =
      get_exten_state_sub(sub);

   if (!exten_state_sub) {
      return;
   }

   ast_str_append(buf, 0, "SubscriptionType: extension_state\r\n"
             "Extension: %s\r\nExtensionStates: %s\r\n",
             exten_state_sub->exten, ast_extension_state2str(
                exten_state_sub->last_exten_state));
}

struct exten_state_pub_data {
   /*! Publishers needing state update */
   AST_VECTOR(name, struct exten_state_publisher *) pubs;
   /*! Body generator state data */
   struct ast_sip_exten_state_data exten_state_data;
};

static void exten_state_pub_data_destroy(struct exten_state_pub_data *doomed)
{
   if (!doomed) {
      return;
   }

   ast_free((void *) doomed->exten_state_data.exten);
   ast_free(doomed->exten_state_data.presence_subtype);
   ast_free(doomed->exten_state_data.presence_message);
   ao2_cleanup(doomed->exten_state_data.device_state_info);

   AST_VECTOR_CALLBACK_VOID(&doomed->pubs, ao2_ref, -1);
   AST_VECTOR_FREE(&doomed->pubs);

   ast_free(doomed);
}

static struct exten_state_pub_data *exten_state_pub_data_alloc(const char *exten, struct ast_state_cb_info *info)
{
   struct exten_state_pub_data *pub_data;

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

   if (AST_VECTOR_INIT(&pub_data->pubs, ao2_container_count(publishers))) {
      exten_state_pub_data_destroy(pub_data);
      return NULL;
   }

   /* Save off currently known information for the body generators. */
   pub_data->exten_state_data.exten = ast_strdup(exten);
   pub_data->exten_state_data.exten_state = info->exten_state;
   pub_data->exten_state_data.presence_state = info->presence_state;
   pub_data->exten_state_data.presence_subtype = ast_strdup(info->presence_subtype);
   pub_data->exten_state_data.presence_message = ast_strdup(info->presence_message);
   pub_data->exten_state_data.device_state_info = ao2_bump(info->device_state_info);
   if (!pub_data->exten_state_data.exten
      || !pub_data->exten_state_data.presence_subtype
      || !pub_data->exten_state_data.presence_message) {
      exten_state_pub_data_destroy(pub_data);
      return NULL;
   }
   return pub_data;
}

/*!
 * \internal
 * \brief Create exten state PUBLISH messages under PJSIP thread.
 * \since 14.0.0
 *
 * \return 0
 */
static int exten_state_publisher_cb(void *data)
{
   struct exten_state_pub_data *pub_data = data;
   struct exten_state_publisher *publisher;
   size_t idx;
   struct ast_str *body_text;
   pj_pool_t *pool;
   struct ast_sip_body_data gen_data = {
      .body_type = AST_SIP_EXTEN_STATE_DATA,
      .body_data = &pub_data->exten_state_data,
   };
   struct ast_sip_body body;

   body_text = ast_str_create(64);
   if (!body_text) {
      exten_state_pub_data_destroy(pub_data);
      return 0;
   }

   /* Need a PJSIP memory pool to generate the bodies. */
   pool = pjsip_endpt_create_pool(ast_sip_get_pjsip_endpoint(), "pub_state_body",
      1024, 1024);
   if (!pool) {
      ast_log(LOG_WARNING, "Exten state publishing unable to create memory pool\n");
      exten_state_pub_data_destroy(pub_data);
      ast_free(body_text);
      return 0;
   }
   pub_data->exten_state_data.pool = pool;

   for (idx = 0; idx < AST_VECTOR_SIZE(&pub_data->pubs); ++idx) {
      const char *uri;
      int res;

      publisher = AST_VECTOR_GET(&pub_data->pubs, idx);

      uri = ast_sip_publish_client_get_user_from_uri(publisher->client, pub_data->exten_state_data.exten,
         pub_data->exten_state_data.local, sizeof(pub_data->exten_state_data.local));
      if (ast_strlen_zero(uri)) {
         ast_log(LOG_WARNING, "PUBLISH client '%s' has no from_uri or server_uri defined.\n",
            publisher->name);
         continue;
      }

      uri = ast_sip_publish_client_get_user_to_uri(publisher->client, pub_data->exten_state_data.exten,
         pub_data->exten_state_data.remote, sizeof(pub_data->exten_state_data.remote));
      if (ast_strlen_zero(uri)) {
         ast_log(LOG_WARNING, "PUBLISH client '%s' has no to_uri or server_uri defined.\n",
            publisher->name);
         continue;
      }

      pub_data->exten_state_data.datastores = publisher->datastores;

      res = ast_sip_pubsub_generate_body_content(publisher->body_type,
         publisher->body_subtype, &gen_data, &body_text);
      pj_pool_reset(pool);
      if (res) {
         ast_log(LOG_WARNING,
            "PUBLISH client '%s' unable to generate %s/%s PUBLISH body.\n",
            publisher->name, publisher->body_type, publisher->body_subtype);
         continue;
      }

      body.type = publisher->body_type;
      body.subtype = publisher->body_subtype;
      body.body_text = ast_str_buffer(body_text);
      ast_sip_publish_client_user_send(publisher->client, pub_data->exten_state_data.exten, &body);
   }

   pjsip_endpt_release_pool(ast_sip_get_pjsip_endpoint(), pool);

   ast_free(body_text);
   exten_state_pub_data_destroy(pub_data);
   return 0;
}

/*!
 * \brief Global extension state callback function
 */
static int exten_state_publisher_state_cb(const char *context, const char *exten, struct ast_state_cb_info *info, void *data)
{
   struct ao2_iterator publisher_iter;
   struct exten_state_publisher *publisher;
   struct exten_state_pub_data *pub_data = NULL;

   ast_debug(5, "Exten state publisher: %s@%s Reason:%s State:%s Presence:%s Subtype:'%s' Message:'%s'\n",
      exten, context,
      info->reason == AST_HINT_UPDATE_DEVICE
         ? "Device"
         : info->reason == AST_HINT_UPDATE_PRESENCE
            ? "Presence"
            : "Unknown",
      ast_extension_state2str(info->exten_state),
      ast_presence_state2str(info->presence_state),
      S_OR(info->presence_subtype, ""),
      S_OR(info->presence_message, ""));
   publisher_iter = ao2_iterator_init(publishers, 0);
   for (; (publisher = ao2_iterator_next(&publisher_iter)); ao2_ref(publisher, -1)) {
      if ((publisher->context_filter && regexec(&publisher->context_regex, context, 0, NULL, 0)) ||
          (publisher->exten_filter && regexec(&publisher->exten_regex, exten, 0, NULL, 0))) {
         continue;
      }

      if (!pub_data) {
         pub_data = exten_state_pub_data_alloc(exten, info);
         if (!pub_data) {
            ao2_ref(publisher, -1);
            break;
         }
      }

      ao2_ref(publisher, +1);
      if (AST_VECTOR_APPEND(&pub_data->pubs, publisher)) {
         ao2_ref(publisher, -1);
      } else {
         ast_debug(5, "'%s' will publish exten state\n", publisher->name);
      }
   }
   ao2_iterator_destroy(&publisher_iter);

   if (pub_data
      && ast_sip_push_task(publish_exten_state_serializer, exten_state_publisher_cb,
         pub_data)) {
      exten_state_pub_data_destroy(pub_data);
   }

   return 0;
}

/*!
 * \brief Hashing function for extension state publisher
 */
static int exten_state_publisher_hash(const void *obj, const int flags)
{
   const struct exten_state_publisher *object;
   const char *key;

   switch (flags & OBJ_SEARCH_MASK) {
   case OBJ_SEARCH_KEY:
      key = obj;
      break;
   case OBJ_SEARCH_OBJECT:
      object = obj;
      key = object->name;
      break;
   default:
      ast_assert(0);
      return 0;
   }
   return ast_str_hash(key);
}

/*!
 * \brief Comparator function for extension state publisher
 */
static int exten_state_publisher_cmp(void *obj, void *arg, int flags)
{
   const struct exten_state_publisher *object_left = obj;
   const struct exten_state_publisher *object_right = arg;
   const char *right_key = arg;
   int cmp;

   switch (flags & OBJ_SEARCH_MASK) {
   case OBJ_SEARCH_OBJECT:
      right_key = object_right->name;
      /* Fall through */
   case OBJ_SEARCH_KEY:
      cmp = strcmp(object_left->name, right_key);
      break;
   case OBJ_SEARCH_PARTIAL_KEY:
      /* Not supported by container. */
      ast_assert(0);
      return 0;
   default:
      cmp = 0;
      break;
   }
   if (cmp) {
      return 0;
   }
   return CMP_MATCH;
}

/*!
 * \brief Destructor for extension state publisher
 */
static void exten_state_publisher_destroy(void *obj)
{
   struct exten_state_publisher *publisher = obj;

   if (publisher->context_filter) {
      regfree(&publisher->context_regex);
   }

   if (publisher->exten_filter) {
      regfree(&publisher->exten_regex);
   }

   ao2_cleanup(publisher->client);
   ao2_cleanup(publisher->datastores);
}

static int build_regex(regex_t *regex, const char *text)
{
   int res;

   if ((res = regcomp(regex, text, REG_EXTENDED | REG_ICASE | REG_NOSUB))) {
      size_t len = regerror(res, regex, NULL, 0);
      char buf[len];
      regerror(res, regex, buf, len);
      ast_log(LOG_ERROR, "Could not compile regex '%s': %s\n", text, buf);
      return -1;
   }

   return 0;
}

static int publisher_start(struct ast_sip_outbound_publish *configuration, struct ast_sip_outbound_publish_client *client)
{
   struct exten_state_publisher *publisher;
   size_t name_size;
   size_t body_type_size;
   size_t body_subtype_size;
   char *body_subtype;
   const char *body_full;
   const char *body_type;
   const char *name;
   const char *context;
   const char *exten;

   name = ast_sorcery_object_get_id(configuration);

   body_full = ast_sorcery_object_get_extended(configuration, "body");
   if (ast_strlen_zero(body_full)) {
      ast_log(LOG_ERROR, "Outbound extension state publisher '%s': Body not set\n",
         name);
      return -1;
   }

   body_subtype = ast_strdupa(body_full);
   body_type = strsep(&body_subtype, "/");
   if (ast_strlen_zero(body_type) || ast_strlen_zero(body_subtype)) {
      ast_log(LOG_ERROR, "Outbound extension state publisher '%s': Body '%s' missing type or subtype\n",
         name, body_full);
      return -1;
   }

   if (!ast_sip_pubsub_is_body_generator_registered(body_type, body_subtype)) {
      ast_log(LOG_ERROR, "Outbound extension state publisher '%s': '%s' body generator not registered\n",
         name, body_full);
      return -1;
   }

   name_size = strlen(name) + 1;
   body_type_size = strlen(body_type) + 1;
   body_subtype_size = strlen(body_subtype) + 1;

   publisher = ao2_alloc_options(
      sizeof(*publisher) + name_size + body_type_size + body_subtype_size,
      exten_state_publisher_destroy, AO2_ALLOC_OPT_LOCK_NOLOCK);
   if (!publisher) {
      return -1;
   }

   ast_copy_string(publisher->name, name, name_size);
   publisher->body_type = publisher->name + name_size;
   ast_copy_string(publisher->body_type, body_type, body_type_size);
   publisher->body_subtype = publisher->body_type + body_type_size;
   ast_copy_string(publisher->body_subtype, body_subtype, body_subtype_size);

   context = ast_sorcery_object_get_extended(configuration, "context");
   if (!ast_strlen_zero(context)) {
      if (build_regex(&publisher->context_regex, context)) {
         ast_log(LOG_ERROR, "Outbound extension state publisher '%s': Could not build context filter '%s'\n",
            name, context);
         ao2_ref(publisher, -1);
         return -1;
      }

      publisher->context_filter = 1;
   }

   exten = ast_sorcery_object_get_extended(configuration, "exten");
   if (!ast_strlen_zero(exten)) {
      if (build_regex(&publisher->exten_regex, exten)) {
         ast_log(LOG_ERROR, "Outbound extension state publisher '%s': Could not build exten filter '%s'\n",
            name, exten);
         ao2_ref(publisher, -1);
         return -1;
      }

      publisher->exten_filter = 1;
   }

   publisher->datastores = ast_datastores_alloc();
   if (!publisher->datastores) {
      ast_log(LOG_ERROR, "Outbound extension state publisher '%s': Could not create datastores container\n",
         name);
      ao2_ref(publisher, -1);
      return -1;
   }

   publisher->client = ao2_bump(client);

   ao2_lock(publishers);
   if (!ao2_container_count(publishers)) {
      ast_extension_state_add(NULL, NULL, exten_state_publisher_state_cb, NULL);
   }
   ao2_link_flags(publishers, publisher, OBJ_NOLOCK);
   ao2_unlock(publishers);

   ao2_ref(publisher, -1);

   return 0;
}

static int publisher_stop(struct ast_sip_outbound_publish_client *client)
{
   ao2_find(publishers, ast_sorcery_object_get_id(client), OBJ_SEARCH_KEY | OBJ_UNLINK | OBJ_NODATA);
   return 0;
}

static int unload_module(void)
{
   ast_sip_unregister_event_publisher_handler(&dialog_publisher);
   ast_sip_unregister_subscription_handler(&dialog_handler);
   ast_sip_unregister_event_publisher_handler(&presence_publisher);
   ast_sip_unregister_subscription_handler(&presence_handler);

   ast_extension_state_del(0, exten_state_publisher_state_cb);

   ast_taskprocessor_unreference(publish_exten_state_serializer);
   publish_exten_state_serializer = NULL;

   ao2_cleanup(publishers);
   publishers = NULL;

   return 0;
}

static int load_module(void)
{
   publishers = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0,
      PUBLISHER_BUCKETS, exten_state_publisher_hash, NULL, exten_state_publisher_cmp);
   if (!publishers) {
      ast_log(LOG_WARNING, "Unable to create container to store extension state publishers\n");
      return AST_MODULE_LOAD_DECLINE;
   }

   publish_exten_state_serializer = ast_sip_create_serializer("pjsip/exten_state");
   if (!publish_exten_state_serializer) {
      unload_module();
      return AST_MODULE_LOAD_DECLINE;
   }

   if (ast_sip_register_subscription_handler(&presence_handler)) {
      ast_log(LOG_WARNING, "Unable to register subscription handler %s\n",
         presence_handler.event_name);
      unload_module();
      return AST_MODULE_LOAD_DECLINE;
   }

   if (ast_sip_register_event_publisher_handler(&presence_publisher)) {
      ast_log(LOG_WARNING, "Unable to register presence publisher %s\n",
         presence_publisher.event_name);
      unload_module();
      return AST_MODULE_LOAD_DECLINE;
   }

   if (ast_sip_register_subscription_handler(&dialog_handler)) {
      ast_log(LOG_WARNING, "Unable to register subscription handler %s\n",
         dialog_handler.event_name);
      unload_module();
      return AST_MODULE_LOAD_DECLINE;
   }

   if (ast_sip_register_event_publisher_handler(&dialog_publisher)) {
      ast_log(LOG_WARNING, "Unable to register presence publisher %s\n",
         dialog_publisher.event_name);
      unload_module();
      return AST_MODULE_LOAD_DECLINE;
   }

   return AST_MODULE_LOAD_SUCCESS;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "PJSIP Extension State Notifications",
   .support_level = AST_MODULE_SUPPORT_CORE,
   .load = load_module,
   .unload = unload_module,
   .load_pri = AST_MODPRI_CHANNEL_DEPEND + 5,
   .requires = "res_pjsip,res_pjsip_pubsub,res_pjsip_outbound_publish",
);