extension_state_legacy.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2026, Sangoma Technologies Corporation
 *
 * Joshua Colp <jcolp@sangoma.com>
 *
 * See https://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
    <support_level>core</support_level>
 ***/
 
#include "asterisk.h"
#include "asterisk/_private.h"
#include "asterisk/module.h"
#include "asterisk/extension_state.h"
#include "asterisk/pbx.h"
#include "asterisk/stasis.h"
#include "asterisk/stasis_message_router.h"
#include "asterisk/astobj2.h"
#include "asterisk/lock.h"
#include "asterisk/vector.h"
 
struct extension_state_legacy_state_cb {
    /*! Watcher ID returned when registered. */
    int id;
    /*! Message router for the traffic to this callback */
    struct stasis_message_router *router;
    /*! Arbitrary data passed for callbacks. */
    void *data;
    /*! Flag if this callback is an extended callback containing detailed device status */
    int extended;
    /*! Callback when state changes. */
    ast_state_cb_type change_cb;
    /*! Callback when destroyed so any resources given by the registerer can be freed. */
    ast_state_cb_destroy_type destroy_cb;
};
 
/*! \brief Lock to protect the callbacks vector */
AST_MUTEX_DEFINE_STATIC(extension_state_legacy_callbacks_lock);
 
/*! \brief Legacy callbacks, the index of it in the vector is the id given to the API user for per-extension */
static AST_VECTOR(, struct extension_state_legacy_state_cb *) extension_state_legacy_callbacks;
 
int ast_extension_state(struct ast_channel *c, const char *context, const char *exten)
{
    struct ast_extension_state_device_snapshot *device_snapshot;
    enum ast_extension_states device_state;
 
    device_snapshot = ast_extension_state_get_latest_device_snapshot(c, exten, context);
    if (!device_snapshot) {
        return -1;
    }
 
    device_state = device_snapshot->state;
    ao2_ref(device_snapshot, -1);
 
    return device_state;
}
 
int ast_hint_presence_state(struct ast_channel *c, const char *context, const char *exten, char **subtype, char **message)
{
    struct ast_extension_state_presence_snapshot *presence_snapshot;
    enum ast_presence_state presence_state;
 
    presence_snapshot = ast_extension_state_get_latest_presence_snapshot(c, exten, context);
    if (!presence_snapshot) {
        return -1;
    }
 
    presence_state = presence_snapshot->presence_state;
    if (presence_snapshot->presence_subtype) {
        *subtype = ast_strdup(presence_snapshot->presence_subtype);
    }
    if (presence_snapshot->presence_message) {
        *message = ast_strdup(presence_snapshot->presence_message);
    }
 
    ao2_ref(presence_snapshot, -1);
 
    return presence_state;
}
 
/*!
 * \internal
 * \brief Destroy function for device state info objects.
 *
 * \param obj The device state info object to destroy.
 */
static void device_state_info_destroy(void *obj)
{
    struct ast_device_state_info *info = obj;
 
    ao2_cleanup(info->causing_channel);
}
 
/*!
 * \internal
 * \brief Add a device state info object to a container.
 *
 * \param device_state_info The container to add the device state info to.
 * \param device_state The device state info to add.
 * \retval 0 on success
 * \retval -1 on failure
 */
static int extension_state_legacy_add_device_state_info(struct ao2_container *device_state_info,
    const struct ast_extension_state_device_state_info *device_state)
{
    struct ast_device_state_info *obj;
 
    obj = ao2_alloc_options(sizeof(*obj) + strlen(device_state->device) + 1, device_state_info_destroy, AO2_ALLOC_OPT_LOCK_NOLOCK);
    if (!obj) {
        return -1;
    }
 
    obj->device_state = device_state->state;
    strcpy(obj->device_name, device_state->device); /* Safe */
    obj->causing_channel = ast_extension_state_get_device_causing_channel(device_state->device, device_state->state);
    ao2_link(device_state_info, obj);
    ao2_ref(obj, -1);
 
    return 0;
}
 
/*!
 * \internal
 * \brief Create a container of device state info objects from an extension device state message.
 *
 * \param device_state_message The extension device state message to create device state info from.
 * \return A container of device state info objects, or NULL on failure.
 */
static struct ao2_container *extension_state_legacy_create_device_state_info(struct ast_extension_state_device_snapshot *device_snapshot)
{
    struct ao2_container *device_state_info = ao2_container_alloc_list(AO2_ALLOC_OPT_LOCK_NOLOCK, 0, NULL, NULL);
    int i;
 
    if (!device_state_info) {
        return NULL;
    }
 
    /*
     * The causing device is not part of additional_devices, but the legacy API
     * expects the device state info to contain every contributing device.
     */
    if (device_snapshot->causing_device &&
        extension_state_legacy_add_device_state_info(device_state_info, device_snapshot->causing_device)) {
        ao2_ref(device_state_info, -1);
        return NULL;
    }
 
    for (i = 0; i < AST_VECTOR_SIZE(&device_snapshot->additional_devices); i++) {
        struct ast_extension_state_device_state_info *source_info = AST_VECTOR_GET(&device_snapshot->additional_devices, i);
 
        if (extension_state_legacy_add_device_state_info(device_state_info, source_info)) {
            ao2_ref(device_state_info, -1);
            return NULL;
        }
    }
 
    return device_state_info;
}
 
int ast_extension_state_extended(struct ast_channel *c, const char *context, const char *exten,
    struct ao2_container **device_state_info)
{
    struct ast_extension_state_device_snapshot *device_snapshot;
    enum ast_extension_states device_state;
 
    device_snapshot = ast_extension_state_get_latest_device_snapshot(c, exten, context);
    if (!device_snapshot) {
        return -1;
    }
 
    device_state = device_snapshot->state;
 
    /* The caller wants device state info, so allocate a container and populate it */
    if (device_state_info) {
        *device_state_info = extension_state_legacy_create_device_state_info(device_snapshot);
    }
 
    ao2_ref(device_snapshot, -1);
 
    return device_state;
}
 
/*!
 * \internal
 * \brief Callback for subscription state change, used for reference handling.
 *
 * \param userdata The user data passed to the subscription.
 * \param sub The subscription that received the message.
 * \param msg The message received by the subscription.
 */
static void extension_state_legacy_subscription_change_cb(void *userdata, struct stasis_subscription *sub,
    struct stasis_message *msg)
{
    if (stasis_subscription_final_message(sub, msg)) {
        ao2_cleanup(userdata);
    }
}
 
/*!
 * \internal
 * \brief Destructor for \ref extension_state_legacy_state_cb.
 *
 * \param obj The extension state legacy state callback object to destroy.
 */
static void extension_state_legacy_state_cb_destroy(void *obj)
{
    struct extension_state_legacy_state_cb *cb = obj;
 
    if (cb->destroy_cb) {
        cb->destroy_cb(cb->id, cb->data);
    }
}
 
/*!
 * \internal
 * \brief Callback for extension state updates.
 *
 * \param userdata The user data passed to the subscription.
 * \param sub The subscription that received the message.
 * \param msg The message received by the subscription.
 */
static void extension_state_legacy_update_cb(void *userdata, struct stasis_subscription *sub,
        struct stasis_message *msg)
{
    struct extension_state_legacy_state_cb *cb = userdata;
    struct ast_extension_state_update_message *update_message = stasis_message_data(msg);
    struct ast_state_cb_info info = {
        .exten_state = update_message->new_device_snapshot->state,
        .presence_state = update_message->new_presence_snapshot->presence_state,
        .presence_subtype = S_OR(update_message->new_presence_snapshot->presence_subtype, ""),
        .presence_message = S_OR(update_message->new_presence_snapshot->presence_message, ""),
    };
 
    /* If the presence has changed, notify the callback */
    if (update_message->new_presence_snapshot != update_message->old_presence_snapshot) {
        info.reason = AST_HINT_UPDATE_PRESENCE;
        cb->change_cb(update_message->context, update_message->extension, &info, cb->data);
    }
 
    /* If the device state has changed, notify the callback */
    if (update_message->new_device_snapshot != update_message->old_device_snapshot) {
        info.reason = AST_HINT_UPDATE_DEVICE;
 
        /* If they want extended information we need to provide the channels */
        if (cb->extended) {
            info.device_state_info = extension_state_legacy_create_device_state_info(update_message->new_device_snapshot);
        }
 
        cb->change_cb(update_message->context, update_message->extension, &info, cb->data);
 
        ao2_cleanup(info.device_state_info);
    }
}
 
/*!
 * \internal
 * \brief Callback for extension state removal updates.
 *
 * \param userdata The user data passed to the subscription.
 * \param sub The subscription that received the message.
 * \param msg The message received by the subscription.
 */
static void extension_state_legacy_remove_cb(void *userdata, struct stasis_subscription *sub,
        struct stasis_message *msg)
{
    struct extension_state_legacy_state_cb *cb = userdata;
    struct ast_extension_state_remove_message *remove_message = stasis_message_data(msg);
    struct ast_state_cb_info info = {
        .reason = AST_HINT_UPDATE_DEVICE,
        .exten_state = AST_EXTENSION_REMOVED,
    };
 
    cb->change_cb(remove_message->context, remove_message->extension, &info, cb->data);
}
 
/*!
 * \internal
 * \brief Add a legacy extension state callback.
 *
 * \param context The context to monitor.
 * \param exten The extension to monitor.
 * \param change_cb The callback to call when the extension state changes.
 * \param destroy_cb The callback to call when the callback is removed.
 * \param data The data to pass to the callback.
 * \param extended Whether to include extended information in the callback.
 * \return The ID of the callback, or -1 on failure.
 */
static int extension_state_legacy_add_destroy(const char *context, const char *exten,
    ast_state_cb_type change_cb, ast_state_cb_destroy_type destroy_cb, void *data, int extended)
{
    struct extension_state_legacy_state_cb *state_cb;
    int id;
 
    state_cb = ao2_alloc_options(sizeof(*state_cb), extension_state_legacy_state_cb_destroy, AO2_ALLOC_OPT_LOCK_NOLOCK);
    if (!state_cb) {
        return -1;
    }
 
    state_cb->change_cb = change_cb;
    state_cb->destroy_cb = destroy_cb;
    state_cb->data = data;
    state_cb->extended = extended;
 
    ast_mutex_lock(&extension_state_legacy_callbacks_lock);
 
    /*
     * Callbacks for both per-extension and all are stored in a single vector which may have gaps in it.
     * When adding a new callback, we look for the first gap in the vector and insert the callback there.
     * If there are no gaps, we append it to the end of the vector.
     * For per-extension the ID of a callback is its index in the vector + 1, since 0 is reserved for "all" callbacks.
     */
    for (id = 0; id < AST_VECTOR_SIZE(&extension_state_legacy_callbacks); id++) {
        if (AST_VECTOR_GET(&extension_state_legacy_callbacks, id)) {
            continue;
        }
 
        state_cb->id = id + 1;
 
        /* This can't fail since the vector would have already resized */
        AST_VECTOR_REPLACE(&extension_state_legacy_callbacks, id, state_cb);
 
        break;
    }
 
    if (!state_cb->id) {
        /* The vector will resize when we append, which can fail, so handle it */
        if (AST_VECTOR_APPEND(&extension_state_legacy_callbacks, state_cb)) {
            ast_mutex_unlock(&extension_state_legacy_callbacks_lock);
            ao2_ref(state_cb, -1);
            return -1;
        }
        state_cb->id = AST_VECTOR_SIZE(&extension_state_legacy_callbacks);
    }
 
    /* At this point it is guaranteed that the callback has been inserted so we can setup
     * the message router to accept messages from the appropriate topic and translate into
     * the legacy callback.
     */
    if (!context && !exten) {
        /*
         * The all topic will receive all extension state updates which can end up being quite
         * a lot, so we use a dedicated thread for each legacy callback to ensure that the
         * pool of stasis threads does not become overloaded.
         */
        state_cb->router = stasis_message_router_create(ast_extension_state_topic_all());
    } else {
        struct stasis_topic *topic = ast_extension_state_topic(exten, context);
 
        /*
         * Per-extension on the other hand will have comparatively few extension state updates
         * so we use the pool for it instead. Additionally the creation of the message router will
         * fail if topic is NULL, so we don't do an explicit check and just let it try.
         */
        state_cb->router = stasis_message_router_create_pool(topic);
        ao2_cleanup(topic);
    }
 
    /* If there is no message router allocated this callback is useless, so bail */
    if (!state_cb->router) {
        AST_VECTOR_REPLACE(&extension_state_legacy_callbacks, state_cb->id - 1, NULL);
        ast_mutex_unlock(&extension_state_legacy_callbacks_lock);
        ao2_ref(state_cb, -1);
        return -1;
    }
 
    /*
     * Each of the message router callbacks translates the extension state messages into
     * the legacy callback format and then calls the legacy callback with the appropriate data.
     */
    stasis_message_router_add(state_cb->router, stasis_subscription_change_type(),
            extension_state_legacy_subscription_change_cb, ao2_bump(state_cb));
    stasis_message_router_add(state_cb->router, ast_extension_state_update_message_type(),
            extension_state_legacy_update_cb, state_cb);
    stasis_message_router_add(state_cb->router, ast_extension_state_remove_message_type(),
            extension_state_legacy_remove_cb, state_cb);
 
    ast_mutex_unlock(&extension_state_legacy_callbacks_lock);
 
    /*
     * We don't hold a reference directly but the vector does and since we haven't given the ID back
     * there's no way for the caller to remove it, thus it has to be valid even now.
     */
    return (!context && !exten) ? 0 : state_cb->id;
}
 
int ast_extension_state_add_destroy(const char *context, const char *exten,
    ast_state_cb_type change_cb, ast_state_cb_destroy_type destroy_cb, void *data)
{
    return extension_state_legacy_add_destroy(context, exten, change_cb, destroy_cb, data, 0);
}
 
int ast_extension_state_add(const char *context, const char *exten,
    ast_state_cb_type change_cb, void *data)
{
    return extension_state_legacy_add_destroy(context, exten, change_cb, NULL, data, 0);
}
 
int ast_extension_state_add_destroy_extended(const char *context, const char *exten,
    ast_state_cb_type change_cb, ast_state_cb_destroy_type destroy_cb, void *data)
{
    return extension_state_legacy_add_destroy(context, exten, change_cb, destroy_cb, data, 1);
}
 
int ast_extension_state_add_extended(const char *context, const char *exten,
    ast_state_cb_type change_cb, void *data)
{
    return extension_state_legacy_add_destroy(context, exten, change_cb, NULL, data, 1);
}
 
int ast_extension_state_del(int id, ast_state_cb_type change_cb)
{
    struct extension_state_legacy_state_cb *cb;
 
    /* A negative id is considered invalid */
    if (id < 0) {
        return -1;
    }
 
    if (!id) {  /* id == 0 is a callback without extension */
        if (!change_cb) {
            return -1;
        }
 
        /*
         * Global callbacks all have the ID of 0 so we need to find the actual index
         * for them in the vector for removal based on callback.
         */
        ast_mutex_lock(&extension_state_legacy_callbacks_lock);
        for (id = 0; id < AST_VECTOR_SIZE(&extension_state_legacy_callbacks); id++) {
            cb = AST_VECTOR_GET(&extension_state_legacy_callbacks, id);
            if (cb && cb->change_cb == change_cb) {
                AST_VECTOR_REPLACE(&extension_state_legacy_callbacks, id, NULL);
                ast_mutex_unlock(&extension_state_legacy_callbacks_lock);
                stasis_message_router_unsubscribe(cb->router);
                ao2_ref(cb, -1);
                return 0;
            }
        }
        ast_mutex_unlock(&extension_state_legacy_callbacks_lock);
 
        return -1;
    }
 
    ast_mutex_lock(&extension_state_legacy_callbacks_lock);
    if (id <= AST_VECTOR_SIZE(&extension_state_legacy_callbacks)) {
        cb = AST_VECTOR_GET(&extension_state_legacy_callbacks, id - 1);
        if (cb) {
            AST_VECTOR_REPLACE(&extension_state_legacy_callbacks, id - 1, NULL);
            ast_mutex_unlock(&extension_state_legacy_callbacks_lock);
            stasis_message_router_unsubscribe(cb->router);
            ao2_ref(cb, -1);
            return 0;
        }
    }
    ast_mutex_unlock(&extension_state_legacy_callbacks_lock);
 
    return -1;
}
 
/*!
 * \internal
 * \brief Clean up the legacy extension state system, called at shutdown.
 *
 * This function unregisters all legacy extension state callbacks and cleans up
 * the associated resources.
 */
static void extension_state_legacy_cleanup(void)
{
    int i;
 
    ast_mutex_lock(&extension_state_legacy_callbacks_lock);
    for (i = 0; i < AST_VECTOR_SIZE(&extension_state_legacy_callbacks); i++) {
        struct extension_state_legacy_state_cb *cb = AST_VECTOR_GET(&extension_state_legacy_callbacks, i);
 
        if (!cb) {
            continue;
        }
 
        AST_VECTOR_REPLACE(&extension_state_legacy_callbacks, i, NULL);
        stasis_message_router_unsubscribe_and_join(cb->router);
        ao2_ref(cb, -1);
    }
    ast_mutex_unlock(&extension_state_legacy_callbacks_lock);
    AST_VECTOR_FREE(&extension_state_legacy_callbacks);
}
 
int ast_extension_state_legacy_init(void)
{
    /* Since we're not pre-allocating for any callbacks this can't fail */
    AST_VECTOR_INIT(&extension_state_legacy_callbacks, 0);
    ast_register_cleanup(extension_state_legacy_cleanup);
 
    return 0;
}