res_stasis_device_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 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",
);