messaging.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2014, Digium, Inc.
 *
 * Matt Jordan <mjordan@digium.com>
 *
 * 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 Stasis out-of-call text message support
 *
 * \author Matt Jordan <mjordan@digium.com>
 */
 
#include "asterisk.h"
 
#include "asterisk/message.h"
#include "asterisk/endpoints.h"
#include "asterisk/astobj2.h"
#include "asterisk/vector.h"
#include "asterisk/lock.h"
#include "asterisk/utils.h"
#include "asterisk/test.h"
#include "messaging.h"
 
/*!
 * \brief Subscription to all technologies
 */
#define TECH_WILDCARD "__AST_ALL_TECH"
 
/*!
 * \brief Number of buckets for the \ref endpoint_subscriptions container
 */
#define ENDPOINTS_NUM_BUCKETS 127
 
/*! \brief Storage object for an application */
struct application_tuple {
    /*! ao2 ref counted private object to pass to the callback */
    void *pvt;
    /*! The callback to call when this application has a message */
    message_received_cb callback;
    /*! The name (key) of the application */
    char app_name[];
};
 
/*! \brief A subscription to some endpoint or technology */
struct message_subscription {
    /*! The applications that have subscribed to this endpoint or tech */
    AST_VECTOR(, struct application_tuple *) applications;
    /*! The name of this endpoint or tech */
    char token[];
};
 
/*! \brief The subscriptions to endpoints */
static struct ao2_container *endpoint_subscriptions;
 
/*!
 * \brief The subscriptions to technologies
 *
 * \note These are stored separately from standard endpoints, given how
 * relatively few of them there are.
 */
static AST_VECTOR(,struct message_subscription *) tech_subscriptions;
 
/*! \brief RWLock for \c tech_subscriptions */
static ast_rwlock_t tech_subscriptions_lock;
 
/*! \internal \brief Destructor for \c application_tuple */
static void application_tuple_dtor(void *obj)
{
    struct application_tuple *tuple = obj;
 
    ao2_cleanup(tuple->pvt);
}
 
/*! \internal \brief Constructor for \c application_tuple */
static struct application_tuple *application_tuple_alloc(const char *app_name, message_received_cb callback, void *pvt)
{
    struct application_tuple *tuple;
    size_t size = sizeof(*tuple) + strlen(app_name) + 1;
 
    ast_assert(callback != NULL);
 
    tuple = ao2_alloc_options(size, application_tuple_dtor, AO2_ALLOC_OPT_LOCK_NOLOCK);
    if (!tuple) {
        return NULL;
    }
 
    strcpy(tuple->app_name, app_name); /* Safe */
    tuple->pvt = ao2_bump(pvt);
    tuple->callback = callback;
 
    return tuple;
}
 
/*! \internal \brief Destructor for \ref message_subscription */
static void message_subscription_dtor(void *obj)
{
    struct message_subscription *sub = obj;
    int i;
 
    for (i = 0; i < AST_VECTOR_SIZE(&sub->applications); i++) {
        struct application_tuple *tuple = AST_VECTOR_GET(&sub->applications, i);
 
        ao2_cleanup(tuple);
    }
    AST_VECTOR_FREE(&sub->applications);
}
 
/*! \internal \brief Constructor for \ref message_subscription */
static struct message_subscription *message_subscription_alloc(const char *token)
{
    struct message_subscription *sub;
    size_t size = sizeof(*sub) + strlen(token) + 1;
 
    sub = ao2_alloc_options(size, message_subscription_dtor, AO2_ALLOC_OPT_LOCK_RWLOCK);
    if (!sub) {
        return NULL;
    }
    strcpy(sub->token, token); /* Safe */
 
    return sub;
}
 
/*! AO2 hash function for \ref message_subscription */
static int message_subscription_hash_cb(const void *obj, const int flags)
{
    const struct message_subscription *sub;
    const char *key;
 
    switch (flags & OBJ_SEARCH_MASK) {
    case OBJ_SEARCH_KEY:
        key = obj;
        break;
    case OBJ_SEARCH_OBJECT:
        sub = obj;
        key = sub->token;
        break;
    default:
        /* Hash can only work on something with a full key. */
        ast_assert(0);
        return 0;
    }
    return ast_str_hash(key);
}
 
/*! AO2 comparison function for \ref message_subscription */
static int message_subscription_compare_cb(void *obj, void *arg, int flags)
{
    const struct message_subscription *object_left = obj;
    const struct message_subscription *object_right = arg;
    const char *right_key = arg;
    int cmp;
 
    switch (flags & OBJ_SEARCH_MASK) {
    case OBJ_SEARCH_OBJECT:
        right_key = object_right->token;
        /* Fall through */
    case OBJ_SEARCH_KEY:
        cmp = strcmp(object_left->token, right_key);
        break;
    case OBJ_SEARCH_PARTIAL_KEY:
        /*
         * We could also use a partial key struct containing a length
         * so strlen() does not get called for every comparison instead.
         */
        cmp = strncmp(object_left->token, right_key, strlen(right_key));
        break;
    default:
        /*
         * What arg points to is specific to this traversal callback
         * and has no special meaning to astobj2.
         */
        cmp = 0;
        break;
    }
    if (cmp) {
        return 0;
    }
    /*
     * At this point the traversal callback is identical to a sorted
     * container.
     */
    return CMP_MATCH;
}
 
/*! \internal \brief Convert a \c ast_msg To/From URI to a Stasis endpoint name */
static void msg_to_endpoint(const struct ast_msg *msg, char *buf, size_t len)
{
    const char *endpoint = ast_msg_get_endpoint(msg);
 
    snprintf(buf, len, "%s%s%s", ast_msg_get_tech(msg),
        ast_strlen_zero(endpoint) ? "" : "/",
        S_OR(endpoint, ""));
}
 
/*! \internal
 * \brief Callback from the \c message API that determines if we can handle
 * this message
 */
static int has_destination_cb(const struct ast_msg *msg)
{
    struct message_subscription *sub;
    int i;
    char buf[256];
 
    msg_to_endpoint(msg, buf, sizeof(buf));
 
    ast_rwlock_rdlock(&tech_subscriptions_lock);
    for (i = 0; i < AST_VECTOR_SIZE(&tech_subscriptions); i++) {
        sub = AST_VECTOR_GET(&tech_subscriptions, i);
 
        if (!sub) {
            continue;
        }
 
        if (!strcmp(sub->token, TECH_WILDCARD)
            || !strncasecmp(sub->token, buf, strlen(sub->token))
            || !strncasecmp(sub->token, buf, strlen(sub->token))) {
            ast_rwlock_unlock(&tech_subscriptions_lock);
            goto match;
        }
 
    }
    ast_rwlock_unlock(&tech_subscriptions_lock);
 
    sub = ao2_find(endpoint_subscriptions, buf, OBJ_SEARCH_KEY);
    if (sub) {
        ao2_ref(sub, -1);
        goto match;
    }
 
    ast_debug(1, "No subscription found for %s\n", buf);
    return 0;
 
match:
    return 1;
}
 
static struct ast_json *msg_to_json(struct ast_msg *msg)
{
    struct ast_json *json_obj;
    struct ast_json *json_vars;
    struct ast_msg_var_iterator *it_vars;
    const char *name;
    const char *value;
 
    it_vars = ast_msg_var_iterator_init(msg);
    if (!it_vars) {
        return NULL;
    }
 
    json_vars = ast_json_object_create();
    if (!json_vars) {
        ast_msg_var_iterator_destroy(it_vars);
        return NULL;
    }
 
    while (ast_msg_var_iterator_next_received(msg, it_vars, &name, &value)) {
        struct ast_json *json_val = ast_json_string_create(value);
        if (!json_val || ast_json_object_set(json_vars, name, json_val)) {
            ast_json_unref(json_vars);
            ast_msg_var_iterator_destroy(it_vars);
            return NULL;
        }
 
        ast_msg_var_unref_current(it_vars);
    }
    ast_msg_var_iterator_destroy(it_vars);
 
    json_obj = ast_json_pack("{s: s, s: s, s: s, s: o}",
        "from", ast_msg_get_from(msg),
        "to", ast_msg_get_to(msg),
        "body", ast_msg_get_body(msg),
        "variables", json_vars);
 
    return json_obj;
}
 
static void dispatch_message(struct message_subscription *sub, const char *endpoint_name, struct ast_json *json_msg)
{
    int i;
 
    ast_debug(3, "Dispatching message to subscription %s for endpoint %s\n",
        sub->token,
        endpoint_name);
    for (i = 0; i < AST_VECTOR_SIZE(&sub->applications); i++) {
        struct application_tuple *tuple = AST_VECTOR_GET(&sub->applications, i);
 
        tuple->callback(endpoint_name, json_msg, tuple->pvt);
    }
}
 
static int handle_msg_cb(struct ast_msg *msg)
{
    /* We have at most 3 subscriptions: TECH_WILDCARD, tech itself, and endpoint. */
    struct message_subscription *matching_subscriptions[3];
    struct message_subscription *sub;
    int i, j;
    int result;
    char buf[256];
    const char *endpoint_name;
    struct ast_json *json_msg;
 
    msg_to_endpoint(msg, buf, sizeof(buf));
    endpoint_name = buf;
    json_msg = msg_to_json(msg);
    if (!json_msg) {
        return -1;
    }
    result = -1;
 
    /* Find subscriptions to TECH_WILDCARD and to the endpoint's technology. */
    ast_rwlock_rdlock(&tech_subscriptions_lock);
    for (i = 0, j = 0; i < AST_VECTOR_SIZE(&tech_subscriptions) && j < 2; i++) {
        sub = AST_VECTOR_GET(&tech_subscriptions, i);
 
        if (!sub) {
            continue;
        }
 
        if (!strcmp(sub->token, TECH_WILDCARD)
            || !strncasecmp(sub->token, buf, strlen(sub->token))) {
            ao2_ref(sub, +1);
            matching_subscriptions[j++] = sub;
        }
    }
    ast_rwlock_unlock(&tech_subscriptions_lock);
 
    /* Find the subscription to this particular endpoint. */
    sub = ao2_find(endpoint_subscriptions, buf, OBJ_SEARCH_KEY);
    if (sub) {
        matching_subscriptions[j++] = sub;
    }
 
    /* Dispatch the message to all matching subscriptions. */
    for (i = 0; i < j; i++) {
        sub = matching_subscriptions[i];
 
        dispatch_message(sub, endpoint_name, json_msg);
 
        ao2_ref(sub, -1);
        result = 0;
    }
 
    ast_json_unref(json_msg);
    return result;
}
 
struct ast_msg_handler ari_msg_handler = {
    .name = "ari",
    .handle_msg = handle_msg_cb,
    .has_destination = has_destination_cb,
};
 
static int messaging_subscription_cmp(struct message_subscription *sub, const char *key)
{
    return !strcmp(sub->token, key) ? 1 : 0;
}
 
static int application_tuple_cmp(struct application_tuple *item, const char *key)
{
    return !strcmp(item->app_name, key) ? 1 : 0;
}
 
static int is_app_subscribed(struct message_subscription *sub, const char *app_name)
{
    int i;
 
    for (i = 0; i < AST_VECTOR_SIZE(&sub->applications); i++) {
        struct application_tuple *tuple;
 
        tuple = AST_VECTOR_GET(&sub->applications, i);
        if (tuple && !strcmp(tuple->app_name, app_name)) {
            return 1;
        }
    }
 
    return 0;
}
 
static struct message_subscription *get_subscription(struct ast_endpoint *endpoint)
{
    struct message_subscription *sub = NULL;
 
    if (endpoint && !ast_strlen_zero(ast_endpoint_get_resource(endpoint))) {
        sub = ao2_find(endpoint_subscriptions, ast_endpoint_get_id(endpoint), OBJ_SEARCH_KEY);
    } else {
        int i;
 
        ast_rwlock_rdlock(&tech_subscriptions_lock);
        for (i = 0; i < AST_VECTOR_SIZE(&tech_subscriptions); i++) {
            sub = AST_VECTOR_GET(&tech_subscriptions, i);
 
            if (sub && !strcmp(sub->token, endpoint ? ast_endpoint_get_tech(endpoint) : TECH_WILDCARD)) {
                ao2_bump(sub);
                break;
            }
 
            /* Need to reset the pointer at this line to prevent from using the wrong subscription due to
             * the token check failing.
             */
            sub = NULL;
        }
        ast_rwlock_unlock(&tech_subscriptions_lock);
    }
 
    return sub;
}
 
void messaging_app_unsubscribe_endpoint(const char *app_name, const char *endpoint_id)
{
    RAII_VAR(struct message_subscription *, sub, NULL, ao2_cleanup);
    RAII_VAR(struct ast_endpoint *, endpoint, NULL, ao2_cleanup);
 
    endpoint = ast_endpoint_find_by_id(endpoint_id);
    sub = get_subscription(endpoint);
    if (!sub) {
        return;
    }
 
    ao2_lock(sub);
    if (!is_app_subscribed(sub, app_name)) {
        ao2_unlock(sub);
        return;
    }
 
    AST_VECTOR_REMOVE_CMP_UNORDERED(&sub->applications, app_name, application_tuple_cmp, ao2_cleanup);
    if (AST_VECTOR_SIZE(&sub->applications) == 0) {
        if (endpoint && !ast_strlen_zero(ast_endpoint_get_resource(endpoint))) {
            ao2_unlink(endpoint_subscriptions, sub);
        } else {
            ast_rwlock_wrlock(&tech_subscriptions_lock);
            AST_VECTOR_REMOVE_CMP_UNORDERED(&tech_subscriptions, endpoint ? ast_endpoint_get_id(endpoint) : TECH_WILDCARD,
                messaging_subscription_cmp, AST_VECTOR_ELEM_CLEANUP_NOOP);
            ast_rwlock_unlock(&tech_subscriptions_lock);
            ao2_ref(sub, -1); /* Release the reference held by tech_subscriptions */
        }
    }
    ao2_unlock(sub);
 
    ast_debug(3, "App '%s' unsubscribed to messages from endpoint '%s'\n", app_name, endpoint ? ast_endpoint_get_id(endpoint) : "-- ALL --");
    ast_test_suite_event_notify("StasisMessagingSubscription", "SubState: Unsubscribed\r\nAppName: %s\r\nToken: %s\r\n",
        app_name, endpoint ? ast_endpoint_get_id(endpoint) : "ALL");
}
 
static struct message_subscription *get_or_create_subscription(struct ast_endpoint *endpoint)
{
    struct message_subscription *sub = get_subscription(endpoint);
 
    if (sub) {
        return sub;
    }
 
    sub = message_subscription_alloc(endpoint ? ast_endpoint_get_id(endpoint) : TECH_WILDCARD);
    if (!sub) {
        return NULL;
    }
 
    /* Either endpoint_subscriptions or tech_subscriptions will hold a reference to
     * the subscription. This reference is released to allow the subscription to
     * eventually destruct when there are no longer any applications receiving
     * events from the subscription.
     */
    if (endpoint && !ast_strlen_zero(ast_endpoint_get_resource(endpoint))) {
        ao2_link(endpoint_subscriptions, sub);
    } else {
        ast_rwlock_wrlock(&tech_subscriptions_lock);
        ao2_ref(sub, +1);
        if (AST_VECTOR_APPEND(&tech_subscriptions, sub)) {
            /* Release the refs that were for the vector and the allocation. */
            ao2_ref(sub, -2);
            sub = NULL;
        }
        ast_rwlock_unlock(&tech_subscriptions_lock);
    }
 
    return sub;
}
 
int messaging_app_subscribe_endpoint(const char *app_name, struct ast_endpoint *endpoint, message_received_cb callback, void *pvt)
{
    RAII_VAR(struct message_subscription *, sub, NULL, ao2_cleanup);
    struct application_tuple *tuple;
 
    sub = get_or_create_subscription(endpoint);
    if (!sub) {
        return -1;
    }
 
    ao2_lock(sub);
    if (is_app_subscribed(sub, app_name)) {
        ao2_unlock(sub);
        return 0;
    }
 
    tuple = application_tuple_alloc(app_name, callback, pvt);
    if (!tuple) {
        ao2_unlock(sub);
        return -1;
    }
    if (AST_VECTOR_APPEND(&sub->applications, tuple)) {
        ao2_ref(tuple, -1);
        ao2_unlock(sub);
        return -1;
    }
    ao2_unlock(sub);
 
    ast_debug(3, "App '%s' subscribed to messages from endpoint '%s'\n", app_name, endpoint ? ast_endpoint_get_id(endpoint) : "-- ALL --");
    ast_test_suite_event_notify("StasisMessagingSubscription", "SubState: Subscribed\r\nAppName: %s\r\nToken: %s\r\n",
        app_name, endpoint ? ast_endpoint_get_id(endpoint) : "ALL");
 
    return 0;
}
 
 
int messaging_cleanup(void)
{
    ast_msg_handler_unregister(&ari_msg_handler);
    ao2_ref(endpoint_subscriptions, -1);
    AST_VECTOR_FREE(&tech_subscriptions);
    ast_rwlock_destroy(&tech_subscriptions_lock);\
 
    return 0;
}
 
int messaging_init(void)
{
    endpoint_subscriptions = ao2_t_container_alloc_hash(AO2_ALLOC_OPT_LOCK_RWLOCK, 0,
        ENDPOINTS_NUM_BUCKETS, message_subscription_hash_cb, NULL,
        message_subscription_compare_cb, "Endpoint messaging subscription container creation");
    if (!endpoint_subscriptions) {
        return -1;
    }
 
    if (AST_VECTOR_INIT(&tech_subscriptions, 4)) {
        ao2_ref(endpoint_subscriptions, -1);
        return -1;
    }
 
    if (ast_rwlock_init(&tech_subscriptions_lock)) {
        ao2_ref(endpoint_subscriptions, -1);
        AST_VECTOR_FREE(&tech_subscriptions);
        return -1;
    }
 
    if (ast_msg_handler_register(&ari_msg_handler)) {
        ao2_ref(endpoint_subscriptions, -1);
        AST_VECTOR_FREE(&tech_subscriptions);
        ast_rwlock_destroy(&tech_subscriptions_lock);
        return -1;
    }
 
    return 0;
}