pjsip_transport_management.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2014, Digium, Inc.
 *
 * Joshua Colp <[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.
 */

#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);
}