res_stasis_device_state.c

Go to the documentation of this file.

/*
 * 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 type="module">res_stasis</depend>
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include "asterisk/astdb.h"
#include "asterisk/astobj2.h"
#include "asterisk/module.h"
#include "asterisk/stasis_app_impl.h"
#include "asterisk/stasis_app_device_state.h"

#define DEVICE_STATE_SIZE 64
/*! astdb family name */
#define DEVICE_STATE_FAMILY "StasisDeviceState"
/*! Stasis device state provider */
#define DEVICE_STATE_PROVIDER_STASIS "Stasis"
/*! Scheme for custom device states */
#define DEVICE_STATE_SCHEME_STASIS "Stasis:"
/*! Scheme for device state subscriptions */
#define DEVICE_STATE_SCHEME_SUB "deviceState:"

/*! Number of hash buckets for device state subscriptions */
#define DEVICE_STATE_BUCKETS 37

/*! The key used for tracking a subscription to all device states */
#define DEVICE_STATE_ALL "__AST_DEVICE_STATE_ALL_TOPIC"

/*! Container for subscribed device states */
static struct ao2_container *device_state_subscriptions;

/*!
 * \brief Device state subscription object.
 */
struct device_state_subscription {
   AST_DECLARE_STRING_FIELDS(
      AST_STRING_FIELD(app_name);
      AST_STRING_FIELD(device_name);
   );
   /*! The subscription object */
   struct stasis_subscription *sub;
};

static int device_state_subscriptions_hash(const void *obj, const int flags)
{
   const struct device_state_subscription *object;

   switch (flags & OBJ_SEARCH_MASK) {
   case OBJ_SEARCH_OBJECT:
      object = obj;
      return ast_str_hash(object->device_name);
   case OBJ_SEARCH_KEY:
   default:
      /* Hash can only work on something with a full key. */
      ast_assert(0);
      return 0;
   }
}

static int device_state_subscriptions_cmp(void *obj, void *arg, int flags)
{
   const struct device_state_subscription *object_left = obj;
   const struct device_state_subscription *object_right = arg;
   int cmp;

   switch (flags & OBJ_SEARCH_MASK) {
   case OBJ_SEARCH_OBJECT:
      /* find objects matching both device and app names */
      if (strcmp(object_left->device_name,
            object_right->device_name)) {
         return 0;
      }
      cmp = strcmp(object_left->app_name, object_right->app_name);
      break;
   case OBJ_SEARCH_KEY:
   case OBJ_SEARCH_PARTIAL_KEY:
      ast_assert(0); /* not supported by container */
      /* fall through */
   default:
      cmp = 0;
      break;
   }

   return cmp ? 0 : CMP_MATCH | CMP_STOP;
}

static void device_state_subscription_destroy(void *obj)
{
   struct device_state_subscription *sub = obj;
   ast_string_field_free_memory(sub);
}

static struct device_state_subscription *device_state_subscription_create(
   const struct stasis_app *app, const char *device_name)
{
   struct device_state_subscription *sub;
   const char *app_name = stasis_app_name(app);
   size_t size;

   if (ast_strlen_zero(device_name)) {
      device_name = DEVICE_STATE_ALL;
   }

   size = strlen(device_name) + strlen(app_name) + 2;

   sub = ao2_alloc(sizeof(*sub), device_state_subscription_destroy);
   if (!sub) {
      return NULL;
   }

   if (ast_string_field_init(sub, size)) {
      ao2_ref(sub, -1);
      return NULL;
   }

   ast_string_field_set(sub, app_name, app_name);
   ast_string_field_set(sub, device_name, device_name);
   return sub;
}

static struct device_state_subscription *find_device_state_subscription(
   struct stasis_app *app, const char *name)
{
   struct device_state_subscription dummy_sub = {
      .app_name = stasis_app_name(app),
      .device_name = name
   };

   return ao2_find(device_state_subscriptions, &dummy_sub, OBJ_SEARCH_OBJECT | OBJ_NOLOCK);
}

static void remove_device_state_subscription(
   struct device_state_subscription *sub)
{
   if (sub->sub) {
      sub->sub = stasis_unsubscribe_and_join(sub->sub);
   }
   ao2_unlink_flags(device_state_subscriptions, sub, OBJ_NOLOCK);
}

struct ast_json *stasis_app_device_state_to_json(
   const char *name, enum ast_device_state state)
{
   return ast_json_pack("{s: s, s: s}",
              "name", name,
              "state", ast_devstate_str(state));
}

struct ast_json *stasis_app_device_states_to_json(void)
{
   struct ast_json *array = ast_json_array_create();
   struct ast_db_entry *tree;
   struct ast_db_entry *entry;

   tree = ast_db_gettree(DEVICE_STATE_FAMILY, NULL);
   for (entry = tree; entry; entry = entry->next) {
      const char *name = strrchr(entry->key, '/');

      if (!ast_strlen_zero(name)) {
         char device[DEVICE_STATE_SIZE];

         snprintf(device, sizeof(device), "%s%s", DEVICE_STATE_SCHEME_STASIS, ++name);
         ast_json_array_append(array,
            stasis_app_device_state_to_json(device, ast_device_state(device)));
      }
   }
   ast_db_freetree(tree);

   return array;
}

static void send_device_state(struct device_state_subscription *sub,
               const char *name, enum ast_device_state state)
{
   RAII_VAR(struct ast_json *, json, NULL, ast_json_unref);

   json = ast_json_pack("{s:s, s:s, s:o, s:o}",
              "type", "DeviceStateChanged",
              "application", sub->app_name,
              "timestamp", ast_json_timeval(ast_tvnow(), NULL),
              "device_state", stasis_app_device_state_to_json(
                 name, state));

   if (!json) {
      ast_log(LOG_ERROR, "Unable to create device state json object\n");
      return;
   }

   stasis_app_send(sub->app_name, json);
}

enum stasis_device_state_result stasis_app_device_state_update(
   const char *name, const char *value)
{
   size_t size = strlen(DEVICE_STATE_SCHEME_STASIS);
   enum ast_device_state state;

   ast_debug(3, "Updating device name = %s, value = %s", name, value);

   if (strncasecmp(name, DEVICE_STATE_SCHEME_STASIS, size)) {
      ast_log(LOG_ERROR, "Update can only be used to set "
         "'%s' device state!\n", DEVICE_STATE_SCHEME_STASIS);
      return STASIS_DEVICE_STATE_NOT_CONTROLLED;
   }

   name += size;
   if (ast_strlen_zero(name)) {
      ast_log(LOG_ERROR, "Update requires custom device name!\n");
      return STASIS_DEVICE_STATE_MISSING;
   }

   if (!value || (state = ast_devstate_val(value)) == AST_DEVICE_UNKNOWN) {
      ast_log(LOG_ERROR, "Unknown device state "
         "value '%s'\n", value);
      return STASIS_DEVICE_STATE_UNKNOWN;
   }

   ast_db_put(DEVICE_STATE_FAMILY, name, value);
   ast_devstate_changed(state, AST_DEVSTATE_CACHABLE, "%s%s",
              DEVICE_STATE_SCHEME_STASIS, name);

   return STASIS_DEVICE_STATE_OK;
}

enum stasis_device_state_result stasis_app_device_state_delete(const char *name)
{
   const char *full_name = name;
   size_t size = strlen(DEVICE_STATE_SCHEME_STASIS);

   if (strncasecmp(name, DEVICE_STATE_SCHEME_STASIS, size)) {
      ast_log(LOG_ERROR, "Can only delete '%s' device states!\n",
         DEVICE_STATE_SCHEME_STASIS);
      return STASIS_DEVICE_STATE_NOT_CONTROLLED;
   }

   name += size;
   if (ast_strlen_zero(name)) {
      ast_log(LOG_ERROR, "Delete requires a device name!\n");
      return STASIS_DEVICE_STATE_MISSING;
   }

   if (ast_device_state_clear_cache(full_name)) {
      return STASIS_DEVICE_STATE_UNKNOWN;
   }

   ast_db_del(DEVICE_STATE_FAMILY, name);

   /* send state change for delete */
   ast_devstate_changed(
      AST_DEVICE_UNKNOWN, AST_DEVSTATE_CACHABLE, "%s%s",
      DEVICE_STATE_SCHEME_STASIS, name);

   return STASIS_DEVICE_STATE_OK;
}

static void populate_cache(void)
{
   RAII_VAR(struct ast_db_entry *, tree,
       ast_db_gettree(DEVICE_STATE_FAMILY, NULL), ast_db_freetree);
   struct ast_db_entry *entry;

   for (entry = tree; entry; entry = entry->next) {
      const char *name = strrchr(entry->key, '/');
      if (!ast_strlen_zero(name)) {
         ast_devstate_changed(
            ast_devstate_val(entry->data),
            AST_DEVSTATE_CACHABLE, "%s%s\n",
            DEVICE_STATE_SCHEME_STASIS, name + 1);
      }
   }
}

static enum ast_device_state stasis_device_state_cb(const char *data)
{
   char buf[DEVICE_STATE_SIZE];

   ast_db_get(DEVICE_STATE_FAMILY, data, buf, sizeof(buf));

   return ast_devstate_val(buf);
}

static void device_state_cb(void *data, struct stasis_subscription *sub,
             struct stasis_message *msg)
{
   struct ast_device_state_message *device_state;

   if (stasis_subscription_final_message(sub, msg)) {
      /* Remove stasis subscription's reference to device_state_subscription */
      ao2_ref(data, -1);
      return;
   }

   if (ast_device_state_message_type() != stasis_message_type(msg)) {
      return;
   }

   device_state = stasis_message_data(msg);
   if (device_state->eid) {
      /* ignore non-aggregate states */
      return;
   }

   send_device_state(data, device_state->device, device_state->state);
}

static void *find_device_state(const struct stasis_app *app, const char *name)
{
   return device_state_subscription_create(app, name);
}

static int is_subscribed_device_state(struct stasis_app *app, const char *name)
{
   struct device_state_subscription *sub;

   sub = find_device_state_subscription(app, DEVICE_STATE_ALL);
   if (sub) {
      ao2_ref(sub, -1);
      return 1;
   }

   sub = find_device_state_subscription(app, name);
   if (sub) {
      ao2_ref(sub, -1);
      return 1;
   }

   return 0;
}

static int is_subscribed_device_state_lock(struct stasis_app *app, const char *name)
{
   int is_subscribed;

   ao2_lock(device_state_subscriptions);
   is_subscribed = is_subscribed_device_state(app, name);
   ao2_unlock(device_state_subscriptions);

   return is_subscribed;
}

static int subscribe_device_state(struct stasis_app *app, void *obj)
{
   struct device_state_subscription *sub = obj;
   struct stasis_topic *topic;

   if (!sub) {
      sub = device_state_subscription_create(app, NULL);
      if (!sub) {
         return -1;
      }
   }

   if (strcmp(sub->device_name, DEVICE_STATE_ALL)) {
      topic = ast_device_state_topic(sub->device_name);
   } else {
      topic = ast_device_state_topic_all();
   }

   ao2_lock(device_state_subscriptions);

   if (is_subscribed_device_state(app, sub->device_name)) {
      ao2_unlock(device_state_subscriptions);
      ast_debug(3, "App %s is already subscribed to %s\n", stasis_app_name(app), sub->device_name);
      return 0;
   }

   ast_debug(3, "Subscribing to device %s\n", sub->device_name);

   sub->sub = stasis_subscribe_pool(topic, device_state_cb, ao2_bump(sub));
   if (!sub->sub) {
      ao2_unlock(device_state_subscriptions);
      ast_log(LOG_ERROR, "Unable to subscribe to device %s\n",
         sub->device_name);
      /* Reference we added when attempting to stasis_subscribe_pool */
      ao2_ref(sub, -1);
      return -1;
   }
   stasis_subscription_accept_message_type(sub->sub, ast_device_state_message_type());
   stasis_subscription_accept_message_type(sub->sub, stasis_subscription_change_type());
   stasis_subscription_set_filter(sub->sub, STASIS_SUBSCRIPTION_FILTER_SELECTIVE);

   ao2_link_flags(device_state_subscriptions, sub, OBJ_NOLOCK);
   ao2_unlock(device_state_subscriptions);

   return 0;
}

static int unsubscribe_device_state(struct stasis_app *app, const char *name)
{
   struct device_state_subscription *sub;

   ao2_lock(device_state_subscriptions);
   sub = find_device_state_subscription(app, name);
   if (sub) {
      remove_device_state_subscription(sub);
   }
   ao2_unlock(device_state_subscriptions);

   ao2_cleanup(sub);

   return 0;
}

static int device_to_json_cb(void *obj, void *arg, void *data, int flags)
{
   struct device_state_subscription *sub = obj;
   const char *app_name = arg;
   struct ast_json *array = data;

   if (strcmp(sub->app_name, app_name)) {
      return 0;
   }

   ast_json_array_append(
      array, ast_json_string_create(sub->device_name));
   return 0;

}

static void devices_to_json(const struct stasis_app *app, struct ast_json *json)
{
   struct ast_json *array = ast_json_array_create();
   ao2_callback_data(device_state_subscriptions, OBJ_NODATA,
           device_to_json_cb, (void *)stasis_app_name(app), array);
   ast_json_object_set(json, "device_names", array);
}

struct stasis_app_event_source device_state_event_source = {
   .scheme = DEVICE_STATE_SCHEME_SUB,
   .find = find_device_state,
   .subscribe = subscribe_device_state,
   .unsubscribe = unsubscribe_device_state,
   .is_subscribed = is_subscribed_device_state_lock,
   .to_json = devices_to_json
};

static int load_module(void)
{
   populate_cache();
   if (ast_devstate_prov_add(DEVICE_STATE_PROVIDER_STASIS,
              stasis_device_state_cb)) {
      return AST_MODULE_LOAD_DECLINE;
   }

   device_state_subscriptions = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0,
      DEVICE_STATE_BUCKETS, device_state_subscriptions_hash, NULL,
      device_state_subscriptions_cmp);
   if (!device_state_subscriptions) {
      ast_devstate_prov_del(DEVICE_STATE_PROVIDER_STASIS);
      return AST_MODULE_LOAD_DECLINE;
   }

   stasis_app_register_event_source(&device_state_event_source);
   return AST_MODULE_LOAD_SUCCESS;
}

static int unload_module(void)
{
   ast_devstate_prov_del(DEVICE_STATE_PROVIDER_STASIS);
   stasis_app_unregister_event_source(&device_state_event_source);
   ao2_cleanup(device_state_subscriptions);
   device_state_subscriptions = NULL;
   return 0;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS, "Stasis application device state support",
   .support_level = AST_MODULE_SUPPORT_CORE,
   .load = load_module,
   .unload = unload_module,
   .requires = "res_stasis",
);