res_pjsip_transport_websocket.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2013, Digium, Inc.
 *
 * Jason Parker <[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.
 */

/*!
 * \brief WebSocket transport module
 */

/*** MODULEINFO
 <depend>pjproject</depend>
 <depend>res_pjsip</depend>
 <depend>res_http_websocket</depend>
 <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include <pjsip.h>
#include <pjsip_ua.h>

#include "asterisk/module.h"
#include "asterisk/http_websocket.h"
#include "asterisk/res_pjsip.h"
#include "asterisk/res_pjsip_session.h"
#include "asterisk/taskprocessor.h"

static int transport_type_wss;
static int transport_type_wss_ipv6;

/*!
 * Used to ensure uniqueness among WS transport names
 */
static int ws_obj_name_serial;

/*!
 * \brief Wrapper for pjsip_transport, for storing the WebSocket session
 */
struct ws_transport {
 pjsip_transport transport;
 pjsip_rx_data rdata;
 struct ast_websocket *ws_session;
};

/*!
 * \brief Send a message over the WebSocket connection.
 *
 * Called by pjsip transport manager.
 */
static pj_status_t ws_send_msg(pjsip_transport *transport,
 pjsip_tx_data *tdata,
 const pj_sockaddr_t *rem_addr,
 int addr_len,
 void *token,
 pjsip_transport_callback callback)
{
 struct ws_transport *wstransport = (struct ws_transport *)transport;
 uint64_t len = tdata->buf.cur - tdata->buf.start;

 if (ast_websocket_write(wstransport->ws_session, AST_WEBSOCKET_OPCODE_TEXT, tdata->buf.start, len)) {
 return PJ_EUNKNOWN;
 }

 return PJ_SUCCESS;
}

/*!
 * \brief Destroy the pjsip transport.
 *
 * Called by pjsip transport manager.
 */
static pj_status_t ws_destroy(pjsip_transport *transport)
{
 struct ws_transport *wstransport = (struct ws_transport *)transport;
 int fd = ast_websocket_fd(wstransport->ws_session);

 if (fd > 0) {
 ast_websocket_close(wstransport->ws_session, 1000);
 shutdown(fd, SHUT_RDWR);
 }

 ao2_ref(wstransport, -1);

 return PJ_SUCCESS;
}

static void transport_dtor(void *arg)
{
 struct ws_transport *wstransport = arg;

 if (wstransport->ws_session) {
 ast_websocket_unref(wstransport->ws_session);
 }

 if (wstransport->transport.ref_cnt) {
 pj_atomic_destroy(wstransport->transport.ref_cnt);
 }

 if (wstransport->transport.lock) {
 pj_lock_destroy(wstransport->transport.lock);
 }

 if (wstransport->transport.endpt && wstransport->transport.pool) {
 pjsip_endpt_release_pool(wstransport->transport.endpt, wstransport->transport.pool);
 }

 if (wstransport->rdata.tp_info.pool) {
 pjsip_endpt_release_pool(wstransport->transport.endpt, wstransport->rdata.tp_info.pool);
 }
}

static int transport_shutdown(void *data)
{
 struct ws_transport *wstransport = data;

 if (!wstransport->transport.is_shutdown && !wstransport->transport.is_destroying) {
 pjsip_transport_shutdown(&wstransport->transport);
 }

 /* Note that the destructor calls PJSIP functions,
 * therefore it must be called in a PJSIP thread.
 */
 ao2_ref(wstransport, -1);

 return 0;
}

struct transport_create_data {
 struct ws_transport *transport;
 struct ast_websocket *ws_session;
};

/*!
 * \brief Create a pjsip transport.
 */
static int transport_create(void *data)
{
 struct transport_create_data *create_data = data;
 struct ws_transport *newtransport = NULL;
 pjsip_tp_state_callback state_cb;

 pjsip_endpoint *endpt = ast_sip_get_pjsip_endpoint();
 struct pjsip_tpmgr *tpmgr = pjsip_endpt_get_tpmgr(endpt);

 char *ws_addr_str;
 pj_pool_t *pool;
 pj_str_t buf;
 pj_status_t status;

 newtransport = ao2_t_alloc_options(sizeof(*newtransport), transport_dtor,
 AO2_ALLOC_OPT_LOCK_NOLOCK, "pjsip websocket transport");
 if (!newtransport) {
 ast_log(LOG_ERROR, "Failed to allocate WebSocket transport.\n");
 goto on_error;
 }

 /* Give websocket transport a unique name for its lifetime */
 snprintf(newtransport->transport.obj_name, PJ_MAX_OBJ_NAME, "ws%p-%d",
 &newtransport->transport, ast_atomic_fetchadd_int(&ws_obj_name_serial, 1));

 newtransport->transport.endpt = endpt;

 if (!(pool = pjsip_endpt_create_pool(endpt, "ws", 512, 512))) {
 ast_log(LOG_ERROR, "Failed to allocate WebSocket endpoint pool.\n");
 goto on_error;
 }

 newtransport->transport.pool = pool;
 newtransport->ws_session = create_data->ws_session;

 /* Keep the session until transport dies */
 ast_websocket_ref(newtransport->ws_session);

 status = pj_atomic_create(pool, 0, &newtransport->transport.ref_cnt);
 if (status != PJ_SUCCESS) {
 goto on_error;
 }

 status = pj_lock_create_recursive_mutex(pool, pool->obj_name, &newtransport->transport.lock);
 if (status != PJ_SUCCESS) {
 goto on_error;
 }

 /*
 * The type_name here is mostly used by log messages eihter in
 * pjproject or Asterisk. Other places are reconstituting subscriptions
 * after a restart (which could never work for a websocket connection anyway),
 * received MESSAGE requests to set PJSIP_TRANSPORT, and most importantly
 * by pjproject when generating the Via header.
 */
 newtransport->transport.type_name = ast_websocket_is_secure(newtransport->ws_session)
 ? "WSS" : "WS";

 ws_addr_str = ast_sockaddr_stringify(ast_websocket_remote_address(newtransport->ws_session));
 ast_debug(4, "Creating websocket transport for %s:%s\n",
 newtransport->transport.type_name, ws_addr_str);

 newtransport->transport.info = (char *) pj_pool_alloc(newtransport->transport.pool,
 strlen(newtransport->transport.type_name) + strlen(ws_addr_str) + sizeof(" to "));
 sprintf(newtransport->transport.info, "%s to %s", newtransport->transport.type_name, ws_addr_str);

 pj_sockaddr_parse(pj_AF_UNSPEC(), 0, pj_cstr(&buf, ws_addr_str), &newtransport->transport.key.rem_addr);
 if (newtransport->transport.key.rem_addr.addr.sa_family == pj_AF_INET6()) {
 newtransport->transport.key.type = transport_type_wss_ipv6;
 } else {
 newtransport->transport.key.type = transport_type_wss;
 }

 newtransport->transport.addr_len = pj_sockaddr_get_len(&newtransport->transport.key.rem_addr);

 ws_addr_str = ast_sockaddr_stringify(ast_websocket_local_address(newtransport->ws_session));
 pj_sockaddr_parse(pj_AF_UNSPEC(), 0, pj_cstr(&buf, ws_addr_str), &newtransport->transport.local_addr);
 pj_strdup2(pool, &newtransport->transport.local_name.host, ast_sockaddr_stringify_addr(ast_websocket_local_address(newtransport->ws_session)));
 newtransport->transport.local_name.port = ast_sockaddr_port(ast_websocket_local_address(newtransport->ws_session));

 newtransport->transport.flag = pjsip_transport_get_flag_from_type((pjsip_transport_type_e)newtransport->transport.key.type);
 newtransport->transport.dir = PJSIP_TP_DIR_INCOMING;
 newtransport->transport.tpmgr = tpmgr;
 newtransport->transport.send_msg = &ws_send_msg;
 newtransport->transport.destroy = &ws_destroy;

 status = pjsip_transport_register(newtransport->transport.tpmgr,
 (pjsip_transport *)newtransport);
 if (status != PJ_SUCCESS) {
 goto on_error;
 }

 /* Add a reference for pjsip transport manager */
 ao2_ref(newtransport, +1);

 newtransport->rdata.tp_info.transport = &newtransport->transport;
 newtransport->rdata.tp_info.pool = pjsip_endpt_create_pool(endpt, "rtd%p",
 PJSIP_POOL_RDATA_LEN, PJSIP_POOL_RDATA_INC);
 if (!newtransport->rdata.tp_info.pool) {
 ast_log(LOG_ERROR, "Failed to allocate WebSocket rdata.\n");
 pjsip_transport_destroy((pjsip_transport *)newtransport);
 goto on_error;
 }

 create_data->transport = newtransport;

 /* Notify application of transport state */
 state_cb = pjsip_tpmgr_get_state_cb(newtransport->transport.tpmgr);
 if (state_cb) {
 pjsip_transport_state_info state_info;

 memset(&state_info, 0, sizeof(state_info));
 state_cb(&newtransport->transport, PJSIP_TP_STATE_CONNECTED, &state_info);
 }

 return 0;

on_error:
 ao2_cleanup(newtransport);
 return -1;
}

struct transport_read_data {
 struct ws_transport *transport;
 char *payload;
 uint64_t payload_len;
};

/*!
 * \brief Pass WebSocket data into pjsip transport manager.
 */
static int transport_read(void *data)
{
 struct transport_read_data *read_data = data;
 struct ws_transport *newtransport = read_data->transport;
 struct ast_websocket *session = newtransport->ws_session;

 pjsip_rx_data *rdata = &newtransport->rdata;
 int recvd;
 pj_str_t buf;
 int pjsip_pkt_len;

 pj_gettimeofday(&rdata->pkt_info.timestamp);

 pjsip_pkt_len = PJSIP_MAX_PKT_LEN < read_data->payload_len ? PJSIP_MAX_PKT_LEN : read_data->payload_len;
 pj_memcpy(rdata->pkt_info.packet, read_data->payload, pjsip_pkt_len);
 rdata->pkt_info.len = pjsip_pkt_len;
 rdata->pkt_info.zero = 0;

 pj_sockaddr_parse(pj_AF_UNSPEC(), 0, pj_cstr(&buf, ast_sockaddr_stringify(ast_websocket_remote_address(session))), &rdata->pkt_info.src_addr);
 rdata->pkt_info.src_addr_len = sizeof(rdata->pkt_info.src_addr);

 pj_ansi_strcpy(rdata->pkt_info.src_name, ast_sockaddr_stringify_addr(ast_websocket_remote_address(session)));
 rdata->pkt_info.src_port = ast_sockaddr_port(ast_websocket_remote_address(session));

 recvd = pjsip_tpmgr_receive_packet(rdata->tp_info.transport->tpmgr, rdata);

 pj_pool_reset(rdata->tp_info.pool);

 return (read_data->payload_len == recvd) ? 0 : -1;
}

static int get_write_timeout(void)
{
 int write_timeout = -1;
 struct ao2_container *transport_states;

 transport_states = ast_sip_get_transport_states();

 if (transport_states) {
 struct ao2_iterator it_transport_states = ao2_iterator_init(transport_states, 0);
 struct ast_sip_transport_state *transport_state;

 for (; (transport_state = ao2_iterator_next(&it_transport_states)); ao2_cleanup(transport_state)) {
 struct ast_sip_transport *transport;

 if (transport_state->type != AST_TRANSPORT_WS && transport_state->type != AST_TRANSPORT_WSS) {
 continue;
 }
 transport = ast_sorcery_retrieve_by_id(ast_sip_get_sorcery(), "transport", transport_state->id);
 if (!transport) {
 continue;
 }
 ast_debug(5, "Found %s transport with write timeout: %d\n",
 transport->type == AST_TRANSPORT_WS ? "WS" : "WSS",
 transport->write_timeout);
 write_timeout = MAX(write_timeout, transport->write_timeout);
 }
 ao2_iterator_destroy(&it_transport_states);
 ao2_cleanup(transport_states);
 }

 if (write_timeout < 0) {
 write_timeout = AST_DEFAULT_WEBSOCKET_WRITE_TIMEOUT;
 }

 ast_debug(1, "Write timeout for WS/WSS transports: %d\n", write_timeout);
 return write_timeout;
}

static struct ast_taskprocessor *create_websocket_serializer(void)
{
 char tps_name[AST_TASKPROCESSOR_MAX_NAME + 1];

 /* Create name with seq number appended. */
 ast_taskprocessor_build_name(tps_name, sizeof(tps_name), "pjsip/websocket");

 return ast_sip_create_serializer(tps_name);
}

/*! \brief WebSocket connection handler. */
static void websocket_cb(struct ast_websocket *session, struct ast_variable *parameters, struct ast_variable *headers)
{
 struct ast_taskprocessor *serializer;
 struct transport_create_data create_data;
 struct ws_transport *transport;
 struct transport_read_data read_data;

 if (ast_websocket_set_nonblock(session)) {
 ast_websocket_unref(session);
 return;
 }

 if (ast_websocket_set_timeout(session, get_write_timeout())) {
 ast_websocket_unref(session);
 return;
 }

 serializer = create_websocket_serializer();
 if (!serializer) {
 ast_websocket_unref(session);
 return;
 }

 create_data.ws_session = session;

 if (ast_sip_push_task_wait_serializer(serializer, transport_create, &create_data)) {
 ast_log(LOG_ERROR, "Could not create WebSocket transport.\n");
 ast_taskprocessor_unreference(serializer);
 ast_websocket_unref(session);
 return;
 }

 transport = create_data.transport;
 read_data.transport = transport;

 while (ast_websocket_wait_for_input(session, -1) > 0) {
 enum ast_websocket_opcode opcode;
 int fragmented;

 if (ast_websocket_read(session, &read_data.payload, &read_data.payload_len, &opcode, &fragmented)) {
 break;
 }

 if (opcode == AST_WEBSOCKET_OPCODE_TEXT || opcode == AST_WEBSOCKET_OPCODE_BINARY) {
 if (read_data.payload_len) {
 ast_sip_push_task_wait_serializer(serializer, transport_read, &read_data);
 }
 } else if (opcode == AST_WEBSOCKET_OPCODE_CLOSE) {
 break;
 }
 }

 ast_sip_push_task_wait_serializer(serializer, transport_shutdown, transport);

 ast_taskprocessor_unreference(serializer);
 ast_websocket_unref(session);
}

/*!
 * \brief Store the transport a message came in on, so it can be used for outbound messages to that contact.
 */
static pj_bool_t websocket_on_rx_msg(pjsip_rx_data *rdata)
{
 static const pj_str_t STR_WS = { "ws", 2 };
 pjsip_contact_hdr *contact;

 long type = rdata->tp_info.transport->key.type;

 if (type != (long) transport_type_wss && type != (long) transport_type_wss_ipv6) {
 return PJ_FALSE;
 }

 contact = pjsip_msg_find_hdr(rdata->msg_info.msg, PJSIP_H_CONTACT, NULL);
 if (contact
 && !contact->star
 && (PJSIP_URI_SCHEME_IS_SIP(contact->uri) || PJSIP_URI_SCHEME_IS_SIPS(contact->uri))) {
 pjsip_sip_uri *uri = pjsip_uri_get_uri(contact->uri);
 const pj_str_t *txp_str = &STR_WS;

 if (DEBUG_ATLEAST(4)) {
 char src_addr_buffer[AST_SOCKADDR_BUFLEN];
 const char *ipv6_s = "", *ipv6_e = "";

 if (pj_strchr(&uri->host, ':')) {
 ipv6_s = "[";
 ipv6_e = "]";
 }

 ast_log(LOG_DEBUG, "%s re-writing Contact URI from %s%.*s%s:%d%s%.*s to %s;transport=%s\n",
 pjsip_rx_data_get_info(rdata),
 ipv6_s, (int) pj_strlen(&uri->host), pj_strbuf(&uri->host), ipv6_e, uri->port,
 pj_strlen(&uri->transport_param) ? ";transport=" : "",
 (int) pj_strlen(&uri->transport_param), pj_strbuf(&uri->transport_param),
 pj_sockaddr_print(&rdata->pkt_info.src_addr, src_addr_buffer, sizeof(src_addr_buffer), 3),
 pj_strbuf(txp_str));
 }

 pj_strdup2(rdata->tp_info.pool, &uri->host, rdata->pkt_info.src_name);
 uri->port = rdata->pkt_info.src_port;
 pj_strdup(rdata->tp_info.pool, &uri->transport_param, txp_str);
 }

 rdata->msg_info.via->rport_param = 0;

 return PJ_FALSE;
}

static pjsip_module websocket_module = {
 .name = { "WebSocket Transport Module", 26 },
 .id = -1,
 .priority = PJSIP_MOD_PRIORITY_TRANSPORT_LAYER,
 .on_rx_request = websocket_on_rx_msg,
 .on_rx_response = websocket_on_rx_msg,
};

/*! \brief Function called when an INVITE goes out */
static void websocket_outgoing_invite_request(struct ast_sip_session *session, struct pjsip_tx_data *tdata)
{
 if (session->inv_session->state == PJSIP_INV_STATE_NULL) {
 pjsip_dlg_add_usage(session->inv_session->dlg, &websocket_module, NULL);
 }
}

/*! \brief Supplement for adding Websocket functionality to dialog */
static struct ast_sip_session_supplement websocket_supplement = {
 .method = "INVITE",
 .priority = AST_SIP_SUPPLEMENT_PRIORITY_FIRST + 1,
 .outgoing_request = websocket_outgoing_invite_request,
};

static int load_module(void)
{
 /*
 * We only need one transport type name (ws) defined. Firefox
 * and Chrome do not support anything other than secure websockets
 * anymore.
 *
 * Also we really cannot have two transports with the same name
 * and address family because it would be ambiguous. Outgoing
 * requests may try to find the transport by name and pjproject
 * only finds the first one registered.
 */
 pjsip_transport_register_type(PJSIP_TRANSPORT_RELIABLE | PJSIP_TRANSPORT_SECURE, "ws", 5060, &transport_type_wss);
 pjsip_transport_register_type(PJSIP_TRANSPORT_RELIABLE | PJSIP_TRANSPORT_SECURE | PJSIP_TRANSPORT_IPV6, "ws", 5060, &transport_type_wss_ipv6);

 if (ast_sip_register_service(&websocket_module) != PJ_SUCCESS) {
 return AST_MODULE_LOAD_DECLINE;
 }

 ast_sip_session_register_supplement(&websocket_supplement);

 if (ast_websocket_add_protocol("sip", websocket_cb)) {
 ast_sip_session_unregister_supplement(&websocket_supplement);
 ast_sip_unregister_service(&websocket_module);
 return AST_MODULE_LOAD_DECLINE;
 }

 return AST_MODULE_LOAD_SUCCESS;
}

static int unload_module(void)
{
 ast_sip_unregister_service(&websocket_module);
 ast_sip_session_unregister_supplement(&websocket_supplement);
 ast_websocket_remove_protocol("sip", websocket_cb);

 return 0;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "PJSIP WebSocket Transport Support",
 .support_level = AST_MODULE_SUPPORT_CORE,
 .load = load_module,
 .unload = unload_module,
 .load_pri = AST_MODPRI_APP_DEPEND,
 .requires = "res_pjsip,res_http_websocket",
);