pjsip_transport_management.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2014, Digium, Inc.
 *
 * Joshua Colp <jcolp@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.
 */
 
#include "asterisk.h"
 
#include <signal.h>
 
#include <pjsip.h>
#include <pjsip_ua.h>
 
#include "asterisk/res_pjsip.h"
#include "asterisk/module.h"
#include "asterisk/astobj2.h"
#include "include/res_pjsip_private.h"
 
/*! \brief Number of buckets for monitored transports */
#define TRANSPORTS_BUCKETS 127
 
#define IDLE_TIMEOUT (pjsip_cfg()->tsx.td)
 
/*! \brief The keep alive packet to send */
static const pj_str_t keepalive_packet = { "\r\n\r\n", 4 };
 
/*! \brief Global container of active transports */
static AO2_GLOBAL_OBJ_STATIC(monitored_transports);
 
/*! \brief Scheduler context for timing out connections with no data received */
static struct ast_sched_context *sched;
 
/*! \brief Thread keeping things alive */
static pthread_t keepalive_thread = AST_PTHREADT_NULL;
 
/*! \brief The global interval at which to send keepalives */
static unsigned int keepalive_interval;
 
/*! \brief Structure for transport to be monitored */
struct monitored_transport {
    /*! \brief The underlying PJSIP transport */
    pjsip_transport *transport;
    /*! \brief Non-zero if a PJSIP request was received */
    int sip_received;
};
 
static void keepalive_transport_send_keepalive(struct monitored_transport *monitored)
{
    pjsip_tpselector selector = {
        .type = PJSIP_TPSELECTOR_TRANSPORT,
        .u.transport = monitored->transport,
    };
 
    pjsip_tpmgr_send_raw(pjsip_endpt_get_tpmgr(ast_sip_get_pjsip_endpoint()),
        monitored->transport->key.type,
        &selector,
        NULL,
        keepalive_packet.ptr,
        keepalive_packet.slen,
        &monitored->transport->key.rem_addr,
        pj_sockaddr_get_len(&monitored->transport->key.rem_addr),
        NULL, NULL);
}
 
/*! \brief Thread which sends keepalives to all active connection-oriented transports */
static void *keepalive_transport_thread(void *data)
{
    struct ao2_container *transports;
    pj_thread_desc desc = { 0 };
    pj_thread_t *thread;
 
    if (pj_thread_register("Asterisk Keepalive Thread", desc, &thread) != PJ_SUCCESS) {
        ast_log(LOG_ERROR, "Could not register keepalive thread with PJLIB, keepalives will not occur.\n");
        return NULL;
    }
 
    transports = ao2_global_obj_ref(monitored_transports);
    if (!transports) {
        return NULL;
    }
 
    /*
     * Once loaded this module just keeps on going as it is unsafe to stop
     * and change the underlying callback for the transport manager.
     */
    while (keepalive_interval) {
        struct ao2_iterator iter;
        struct monitored_transport *monitored;
 
        sleep(keepalive_interval);
 
        /*
         * We must use the iterator to avoid deadlock between the container lock
         * and the pjproject transport manager group lock when sending
         * the keepalive packet.
         */
        iter = ao2_iterator_init(transports, 0);
        for (; (monitored = ao2_iterator_next(&iter)); ao2_ref(monitored, -1)) {
            keepalive_transport_send_keepalive(monitored);
        }
        ao2_iterator_destroy(&iter);
    }
 
    ao2_ref(transports, -1);
    return NULL;
}
 
AST_THREADSTORAGE(desc_storage);
 
static int idle_sched_init_pj_thread(void)
{
    if (!pj_thread_is_registered()) {
        pj_thread_t *thread;
        pj_thread_desc *desc;
 
        desc = ast_threadstorage_get(&desc_storage, sizeof(pj_thread_desc));
        if (!desc) {
            ast_log(LOG_ERROR, "Could not get thread desc from thread-local storage.\n");
            return -1;
        }
 
        pj_bzero(*desc, sizeof(*desc));
 
        pj_thread_register("Transport Monitor", *desc, &thread);
    }
 
    return 0;
}
 
static struct monitored_transport *get_monitored_transport_by_name(const char *obj_name)
{
    struct ao2_container *transports;
    struct monitored_transport *monitored = NULL;
 
    transports = ao2_global_obj_ref(monitored_transports);
    if (transports) {
        monitored = ao2_find(transports, obj_name, OBJ_SEARCH_KEY);
    }
    ao2_cleanup(transports);
 
    /* Caller is responsible for cleaning up reference */
    return monitored;
}
 
static int idle_sched_cb(const void *data)
{
    char *obj_name = (char *) data;
    struct monitored_transport *monitored;
 
    if (idle_sched_init_pj_thread()) {
        ast_free(obj_name);
        return 0;
    }
 
    monitored = get_monitored_transport_by_name(obj_name);
    if (monitored) {
        if (!monitored->sip_received) {
            ast_log(LOG_NOTICE, "Shutting down transport '%s' since no request was received in %d seconds\n",
                monitored->transport->info, IDLE_TIMEOUT / 1000);
            pjsip_transport_shutdown(monitored->transport);
        }
        ao2_ref(monitored, -1);
    }
 
    ast_free(obj_name);
    return 0;
}
 
static int idle_sched_cleanup(const void *data)
{
    char *obj_name = (char *) data;
    struct monitored_transport *monitored;
 
    if (idle_sched_init_pj_thread()) {
        ast_free(obj_name);
        return 0;
    }
 
    monitored = get_monitored_transport_by_name(obj_name);
    if (monitored) {
        pjsip_transport_shutdown(monitored->transport);
        ao2_ref(monitored, -1);
    }
 
    ast_free(obj_name);
    return 0;
}
 
/*! \brief Destructor for keepalive transport */
static void monitored_transport_destroy(void *obj)
{
    struct monitored_transport *monitored = obj;
 
    pjsip_transport_dec_ref(monitored->transport);
}
 
/*! \brief Callback invoked when transport changes occur */
static void monitored_transport_state_callback(pjsip_transport *transport, pjsip_transport_state state,
    const pjsip_transport_state_info *info)
{
    struct ao2_container *transports;
 
    /* We only care about reliable transports */
    if (PJSIP_TRANSPORT_IS_RELIABLE(transport)
        && (transport->dir == PJSIP_TP_DIR_INCOMING || keepalive_interval)
        && (transports = ao2_global_obj_ref(monitored_transports))) {
        struct monitored_transport *monitored;
 
        switch (state) {
        case PJSIP_TP_STATE_CONNECTED:
            monitored = ao2_alloc_options(sizeof(*monitored),
                monitored_transport_destroy, AO2_ALLOC_OPT_LOCK_NOLOCK);
            if (!monitored) {
                break;
            }
            monitored->transport = transport;
            pjsip_transport_add_ref(monitored->transport);
 
            ao2_link(transports, monitored);
 
            if (transport->dir == PJSIP_TP_DIR_INCOMING) {
                char *obj_name = ast_strdup(transport->obj_name);
 
                if (!obj_name
                   || ast_sched_add_variable(sched, IDLE_TIMEOUT, idle_sched_cb, obj_name, 1) < 0) {
                    /* Shut down the transport if anything fails */
                    pjsip_transport_shutdown(transport);
                    ast_free(obj_name);
                }
            }
            ao2_ref(monitored, -1);
            break;
        case PJSIP_TP_STATE_SHUTDOWN:
        case PJSIP_TP_STATE_DISCONNECTED:
            ao2_find(transports, transport->obj_name, OBJ_SEARCH_KEY | OBJ_NODATA | OBJ_UNLINK);
            break;
        default:
            break;
        }
 
        ao2_ref(transports, -1);
    }
}
 
struct ast_sip_tpmgr_state_callback monitored_transport_reg = {
    monitored_transport_state_callback,
};
 
/*! \brief Hashing function for monitored transport */
static int monitored_transport_hash_fn(const void *obj, int flags)
{
    const struct monitored_transport *object;
    const char *key;
 
    switch (flags & OBJ_SEARCH_MASK) {
    case OBJ_SEARCH_KEY:
        key = obj;
        break;
    case OBJ_SEARCH_OBJECT:
        object = obj;
        key = object->transport->obj_name;
        break;
    default:
        /* Hash can only work on something with a full key. */
        ast_assert(0);
        return 0;
    }
    return ast_str_hash(key);
}
 
/*! \brief Comparison function for monitored transport */
static int monitored_transport_cmp_fn(void *obj, void *arg, int flags)
{
    const struct monitored_transport *object_left = obj;
    const struct monitored_transport *object_right = arg;
    const char *right_key = arg;
    int cmp;
 
    switch (flags & OBJ_SEARCH_MASK) {
    case OBJ_SEARCH_OBJECT:
        right_key = object_right->transport->obj_name;
        /* Fall through */
    case OBJ_SEARCH_KEY:
        cmp = strcmp(object_left->transport->obj_name, 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->transport->obj_name, 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;
    }
 
    return !cmp ? CMP_MATCH : 0;
}
 
static void keepalive_global_loaded(const char *object_type)
{
    unsigned int new_interval = ast_sip_get_keep_alive_interval();
 
    if (new_interval) {
        keepalive_interval = new_interval;
    } else if (keepalive_interval) {
        ast_log(LOG_NOTICE, "Keepalive support can not be disabled once activated.\n");
        return;
    } else {
        /* This will occur if no keepalive interval has been specified at initial start */
        return;
    }
 
    if (keepalive_thread != AST_PTHREADT_NULL) {
        return;
    }
 
    if (ast_pthread_create(&keepalive_thread, NULL, keepalive_transport_thread, NULL)) {
        ast_log(LOG_ERROR, "Could not create thread for sending keepalive messages.\n");
        keepalive_thread = AST_PTHREADT_NULL;
        keepalive_interval = 0;
    }
}
 
/*! \brief Observer which is used to update our interval when the global setting changes */
static struct ast_sorcery_observer keepalive_global_observer = {
    .loaded = keepalive_global_loaded,
};
 
/*!
 * \brief
 * On incoming TCP connections, when we receive a SIP request, we mark that we have
 * received a valid SIP request. This way, we will not shut the transport down for
 * idleness
 */
static pj_bool_t idle_monitor_on_rx_request(pjsip_rx_data *rdata)
{
    struct monitored_transport *idle_trans;
 
    idle_trans = get_monitored_transport_by_name(rdata->tp_info.transport->obj_name);
    if (idle_trans) {
        idle_trans->sip_received = 1;
        ao2_ref(idle_trans, -1);
    }
 
    return PJ_FALSE;
}
 
static pjsip_module idle_monitor_module = {
    .name = {"idle monitor module", 19},
    .priority = PJSIP_MOD_PRIORITY_TRANSPORT_LAYER + 3,
    .on_rx_request = idle_monitor_on_rx_request,
};
 
int ast_sip_initialize_transport_management(void)
{
    struct ao2_container *transports;
 
    transports = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0, TRANSPORTS_BUCKETS,
        monitored_transport_hash_fn, NULL, monitored_transport_cmp_fn);
    if (!transports) {
        ast_log(LOG_ERROR, "Could not create container for transports to perform keepalive on.\n");
        return AST_MODULE_LOAD_DECLINE;
    }
    ao2_global_obj_replace_unref(monitored_transports, transports);
    ao2_ref(transports, -1);
 
    sched = ast_sched_context_create();
    if (!sched) {
        ast_log(LOG_ERROR, "Failed to create keepalive scheduler context.\n");
        ao2_global_obj_release(monitored_transports);
        return AST_MODULE_LOAD_DECLINE;
    }
 
    if (ast_sched_start_thread(sched)) {
        ast_log(LOG_ERROR, "Failed to start keepalive scheduler thread\n");
        ast_sched_context_destroy(sched);
        sched = NULL;
        ao2_global_obj_release(monitored_transports);
        return AST_MODULE_LOAD_DECLINE;
    }
 
    ast_sip_register_service(&idle_monitor_module);
 
    ast_sip_transport_state_register(&monitored_transport_reg);
 
    ast_sorcery_observer_add(ast_sip_get_sorcery(), "global", &keepalive_global_observer);
    ast_sorcery_reload_object(ast_sip_get_sorcery(), "global");
 
    return AST_MODULE_LOAD_SUCCESS;
}
 
void ast_sip_destroy_transport_management(void)
{
    if (keepalive_interval) {
        keepalive_interval = 0;
        if (keepalive_thread != AST_PTHREADT_NULL) {
            pthread_kill(keepalive_thread, SIGURG);
            pthread_join(keepalive_thread, NULL);
            keepalive_thread = AST_PTHREADT_NULL;
        }
    }
 
    ast_sorcery_observer_remove(ast_sip_get_sorcery(), "global", &keepalive_global_observer);
 
    ast_sip_transport_state_unregister(&monitored_transport_reg);
 
    ast_sip_unregister_service(&idle_monitor_module);
 
    ast_sched_clean_by_callback(sched, idle_sched_cb, idle_sched_cleanup);
    ast_sched_context_destroy(sched);
    sched = NULL;
 
    ao2_global_obj_release(monitored_transports);
}