asterisk/res/res_pjsip_nat.c

556 lines
18 KiB
C

/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 2013, 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.
*/
/*** MODULEINFO
<depend>pjproject</depend>
<depend>res_pjsip</depend>
<depend>res_pjsip_session</depend>
<support_level>core</support_level>
***/
#include "asterisk.h"
#include <pjsip.h>
#include <pjsip_ua.h>
#include "asterisk/res_pjsip.h"
#include "asterisk/res_pjsip_session.h"
#include "asterisk/module.h"
#include "asterisk/acl.h"
/*! URI parameter for original host/port */
#define AST_SIP_X_AST_ORIG_HOST "x-ast-orig-host"
#define AST_SIP_X_AST_ORIG_HOST_LEN 15
#define is_sip_uri(uri) \
(PJSIP_URI_SCHEME_IS_SIP(uri) || PJSIP_URI_SCHEME_IS_SIPS(uri))
static void save_orig_contact_host(pjsip_rx_data *rdata, pjsip_sip_uri *uri)
{
pjsip_param *x_orig_host;
pj_str_t p_value;
#define COLON_LEN 1
#define MAX_PORT_LEN 5
if (rdata->msg_info.msg->type != PJSIP_REQUEST_MSG ||
rdata->msg_info.msg->line.req.method.id != PJSIP_REGISTER_METHOD) {
return;
}
ast_debug(1, "Saving contact '%.*s:%d'\n",
(int)uri->host.slen, uri->host.ptr, uri->port);
x_orig_host = PJ_POOL_ALLOC_T(rdata->tp_info.pool, pjsip_param);
x_orig_host->name = pj_strdup3(rdata->tp_info.pool, AST_SIP_X_AST_ORIG_HOST);
p_value.slen = pj_strlen(&uri->host) + COLON_LEN + MAX_PORT_LEN;
p_value.ptr = (char*)pj_pool_alloc(rdata->tp_info.pool, p_value.slen + 1);
p_value.slen = snprintf(p_value.ptr, p_value.slen + 1, "%.*s:%d", (int)uri->host.slen, uri->host.ptr, uri->port);
pj_strassign(&x_orig_host->value, &p_value);
pj_list_insert_before(&uri->other_param, x_orig_host);
return;
}
static void rewrite_uri(pjsip_rx_data *rdata, pjsip_sip_uri *uri, pj_pool_t *pool)
{
if (pj_strcmp2(&uri->host, rdata->pkt_info.src_name) != 0) {
save_orig_contact_host(rdata, uri);
}
pj_strdup2(pool, &uri->host, rdata->pkt_info.src_name);
uri->port = rdata->pkt_info.src_port;
if (!strcasecmp("WSS", rdata->tp_info.transport->type_name)) {
/* WSS is special, we don't want to overwrite the URI at all as it needs to be ws */
} else if (strcasecmp("udp", rdata->tp_info.transport->type_name)) {
uri->transport_param = pj_str(rdata->tp_info.transport->type_name);
} else {
uri->transport_param.slen = 0;
}
}
/*
* Update the Record-Route headers in the request or response and in the dialog
* object if exists.
*
* When NAT is in use, the address of the next hop in the SIP may be incorrect.
* To address this asterisk uses two strategies in parallel:
* 1. intercept the messages at the transaction level and rewrite the
* messages before arriving at the dialog layer
* 2. after the application processing, update the dialog object with the
* correct information
*
* The first strategy has a limitation that the SIP message may not have all
* the information required to determine if the next hop is in the route set
* or in the contact. Causing risk that asterisk will update the Contact on
* receipt of an in-dialog message despite there being a route set saved in
* the dialog.
*
* The second strategy has a limitation that not all UAC layers have interfaces
* available to invoke this module after dialog creation. (pjsip_sesion does
* but pjsip_pubsub does not), thus this strategy can't update the dialog in
* all cases needed.
*
* The ideal solution would be to implement an "incomming_request" event
* in pubsub module that can then pass the dialog object to this module
* on SUBSCRIBE, this module then should add itself as a listener to the dialog
* for the subsequent requests and responses & then be able to properly update
* the dialog object for all required events.
*/
static int rewrite_route_set(pjsip_rx_data *rdata, pjsip_dialog *dlg)
{
pjsip_rr_hdr *rr = NULL;
pjsip_sip_uri *uri;
int res = -1;
int ignore_rr = 0;
int pubsub = 0;
if (rdata->msg_info.msg->type == PJSIP_RESPONSE_MSG) {
pjsip_hdr *iter;
for (iter = rdata->msg_info.msg->hdr.prev; iter != &rdata->msg_info.msg->hdr; iter = iter->prev) {
if (iter->type == PJSIP_H_RECORD_ROUTE) {
rr = (pjsip_rr_hdr *)iter;
break;
}
}
} else if (pjsip_method_cmp(&rdata->msg_info.msg->line.req.method, &pjsip_register_method)) {
rr = pjsip_msg_find_hdr(rdata->msg_info.msg, PJSIP_H_RECORD_ROUTE, NULL);
} else {
/**
* Record-Route header has no meaning in REGISTER requests
* and should be ignored
*/
ignore_rr = 1;
}
if (!pjsip_method_cmp(&rdata->msg_info.cseq->method, &pjsip_subscribe_method) ||
!pjsip_method_cmp(&rdata->msg_info.cseq->method, &pjsip_notify_method)) {
/**
* There is currently no good way to get the dlg object for a pubsub dialog
* so we will just look at the rr & contact of the current message and
* hope for the best
*/
pubsub = 1;
}
if (rr) {
uri = pjsip_uri_get_uri(&rr->name_addr);
rewrite_uri(rdata, uri, rdata->tp_info.pool);
res = 0;
}
if (dlg && !pj_list_empty(&dlg->route_set) && !dlg->route_set_frozen) {
pjsip_routing_hdr *route = dlg->route_set.next;
uri = pjsip_uri_get_uri(&route->name_addr);
rewrite_uri(rdata, uri, dlg->pool);
res = 0;
}
if (!dlg && !rr && !ignore_rr && !pubsub && rdata->msg_info.to->tag.slen){
/**
* Even if this message doesn't have any route headers
* the dialog may, so wait until a later invocation that
* has a dialog reference to make sure there isn't a
* previously saved routset in the dialog before deciding
* the contact needs to be modified
*/
res = 0;
}
return res;
}
static int rewrite_contact(pjsip_rx_data *rdata, pjsip_dialog *dlg)
{
pjsip_contact_hdr *contact;
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);
rewrite_uri(rdata, uri, rdata->tp_info.pool);
if (dlg && pj_list_empty(&dlg->route_set) && (!dlg->remote.contact
|| pjsip_uri_cmp(PJSIP_URI_IN_REQ_URI, dlg->remote.contact->uri, contact->uri))) {
dlg->remote.contact = (pjsip_contact_hdr*)pjsip_hdr_clone(dlg->pool, contact);
dlg->target = dlg->remote.contact->uri;
}
return 0;
}
return -1;
}
static pj_bool_t handle_rx_message(struct ast_sip_endpoint *endpoint, pjsip_rx_data *rdata)
{
pjsip_dialog *dlg = pjsip_rdata_get_dlg(rdata);
if (!endpoint) {
return PJ_FALSE;
}
if (endpoint->nat.rewrite_contact) {
/* rewrite_contact is intended to ensure we send requests/responses to
* a routable address when NAT is involved. The URI that dictates where
* we send requests/responses can be determined either by Record-Route
* headers or by the Contact header if no Record-Route headers are present.
* We therefore will attempt to rewrite a Record-Route header first, and if
* none are present, we fall back to rewriting the Contact header instead.
*/
if (rewrite_route_set(rdata, dlg)) {
rewrite_contact(rdata, dlg);
}
}
if (endpoint->nat.force_rport) {
rdata->msg_info.via->rport_param = rdata->pkt_info.src_port;
}
return PJ_FALSE;
}
static pj_bool_t nat_on_rx_message(pjsip_rx_data *rdata)
{
pj_bool_t res;
struct ast_sip_endpoint *endpoint;
endpoint = ast_pjsip_rdata_get_endpoint(rdata);
res = handle_rx_message(endpoint, rdata);
ao2_cleanup(endpoint);
return res;
}
/*! \brief Structure which contains information about a transport */
struct request_transport_details {
/*! \brief Type of transport */
enum ast_transport type;
/*! \brief Potential pointer to the transport itself, if UDP */
pjsip_transport *transport;
/*! \brief Potential pointer to the transport factory itself, if TCP/TLS */
pjsip_tpfactory *factory;
/*! \brief Local address for transport */
pj_str_t local_address;
/*! \brief Local port for transport */
int local_port;
};
/*! \brief Callback function for finding the transport the request is going out on */
static int find_transport_state_in_use(void *obj, void *arg, int flags)
{
struct ast_sip_transport_state *transport_state = obj;
struct request_transport_details *details = arg;
/* If an explicit transport or factory matches then this is what is in use, if we are unavailable
* to compare based on that we make sure that the type is the same and the source IP address/port are the same
*/
if (transport_state && ((details->transport && details->transport == transport_state->transport) ||
(details->factory && details->factory == transport_state->factory) ||
((details->type == transport_state->type) && (transport_state->factory) &&
!pj_strcmp(&transport_state->factory->addr_name.host, &details->local_address) &&
transport_state->factory->addr_name.port == details->local_port))) {
return CMP_MATCH;
}
return 0;
}
/*! \brief Helper function which returns the SIP URI of a Contact header */
static pjsip_sip_uri *nat_get_contact_sip_uri(pjsip_tx_data *tdata)
{
pjsip_contact_hdr *contact = pjsip_msg_find_hdr(tdata->msg, PJSIP_H_CONTACT, NULL);
if (!contact || (!PJSIP_URI_SCHEME_IS_SIP(contact->uri) && !PJSIP_URI_SCHEME_IS_SIPS(contact->uri))) {
return NULL;
}
return pjsip_uri_get_uri(contact->uri);
}
/*! \brief Structure which contains hook details */
struct nat_hook_details {
/*! \brief Outgoing message itself */
pjsip_tx_data *tdata;
/*! \brief Chosen transport */
struct ast_sip_transport *transport;
};
/*! \brief Callback function for invoking hooks */
static int nat_invoke_hook(void *obj, void *arg, int flags)
{
struct ast_sip_nat_hook *hook = obj;
struct nat_hook_details *details = arg;
if (hook->outgoing_external_message) {
hook->outgoing_external_message(details->tdata, details->transport);
}
return 0;
}
static void restore_orig_contact_host(pjsip_tx_data *tdata)
{
pjsip_contact_hdr *contact;
pj_str_t x_name = { AST_SIP_X_AST_ORIG_HOST, AST_SIP_X_AST_ORIG_HOST_LEN };
pjsip_param *x_orig_host;
pjsip_sip_uri *uri;
pjsip_hdr *hdr;
if (tdata->msg->type == PJSIP_REQUEST_MSG) {
if (is_sip_uri(tdata->msg->line.req.uri)) {
uri = pjsip_uri_get_uri(tdata->msg->line.req.uri);
while ((x_orig_host = pjsip_param_find(&uri->other_param, &x_name))) {
pj_list_erase(x_orig_host);
}
}
for (hdr = tdata->msg->hdr.next; hdr != &tdata->msg->hdr; hdr = hdr->next) {
if (hdr->type == PJSIP_H_TO) {
if (is_sip_uri(((pjsip_fromto_hdr *) hdr)->uri)) {
uri = pjsip_uri_get_uri(((pjsip_fromto_hdr *) hdr)->uri);
while ((x_orig_host = pjsip_param_find(&uri->other_param, &x_name))) {
pj_list_erase(x_orig_host);
}
}
}
}
}
if (tdata->msg->type != PJSIP_RESPONSE_MSG) {
return;
}
contact = pjsip_msg_find_hdr(tdata->msg, PJSIP_H_CONTACT, NULL);
while (contact) {
pjsip_sip_uri *contact_uri = pjsip_uri_get_uri(contact->uri);
x_orig_host = pjsip_param_find(&contact_uri->other_param, &x_name);
if (x_orig_host) {
char host_port[x_orig_host->value.slen + 1];
char *sep;
ast_debug(1, "Restoring contact %.*s:%d to %.*s\n", (int)contact_uri->host.slen,
contact_uri->host.ptr, contact_uri->port,
(int)x_orig_host->value.slen, x_orig_host->value.ptr);
strncpy(host_port, x_orig_host->value.ptr, x_orig_host->value.slen);
host_port[x_orig_host->value.slen] = '\0';
sep = strchr(host_port, ':');
if (sep) {
*sep = '\0';
sep++;
pj_strdup2(tdata->pool, &contact_uri->host, host_port);
contact_uri->port = strtol(sep, NULL, 10);
}
pj_list_erase(x_orig_host);
}
contact = pjsip_msg_find_hdr(tdata->msg, PJSIP_H_CONTACT, contact->next);
}
}
static pj_status_t process_nat(pjsip_tx_data *tdata)
{
RAII_VAR(struct ao2_container *, transport_states, NULL, ao2_cleanup);
RAII_VAR(struct ast_sip_transport *, transport, NULL, ao2_cleanup);
RAII_VAR(struct ast_sip_transport_state *, transport_state, NULL, ao2_cleanup);
struct request_transport_details details = { 0, };
pjsip_via_hdr *via = NULL;
struct ast_sockaddr addr = { { 0, } };
pjsip_sip_uri *uri = NULL;
RAII_VAR(struct ao2_container *, hooks, NULL, ao2_cleanup);
/* If a transport selector is in use we know the transport or factory, so explicitly find it */
if (tdata->tp_sel.type == PJSIP_TPSELECTOR_TRANSPORT) {
details.transport = tdata->tp_sel.u.transport;
} else if (tdata->tp_sel.type == PJSIP_TPSELECTOR_LISTENER) {
details.factory = tdata->tp_sel.u.listener;
} else if (tdata->tp_info.transport->key.type == PJSIP_TRANSPORT_UDP || tdata->tp_info.transport->key.type == PJSIP_TRANSPORT_UDP6) {
/* Connectionless uses the same transport for all requests */
details.type = AST_TRANSPORT_UDP;
details.transport = tdata->tp_info.transport;
} else {
if (tdata->tp_info.transport->key.type == PJSIP_TRANSPORT_TCP) {
details.type = AST_TRANSPORT_TCP;
} else if (tdata->tp_info.transport->key.type == PJSIP_TRANSPORT_TLS) {
details.type = AST_TRANSPORT_TLS;
} else {
/* Unknown transport type, we can't map and thus can't apply NAT changes */
return PJ_SUCCESS;
}
if ((uri = nat_get_contact_sip_uri(tdata))) {
details.local_address = uri->host;
details.local_port = uri->port;
} else if ((tdata->msg->type == PJSIP_REQUEST_MSG) &&
(via = pjsip_msg_find_hdr(tdata->msg, PJSIP_H_VIA, NULL))) {
details.local_address = via->sent_by.host;
details.local_port = via->sent_by.port;
} else {
return PJ_SUCCESS;
}
if (!details.local_port) {
details.local_port = (details.type == AST_TRANSPORT_TLS) ? 5061 : 5060;
}
}
if (!(transport_states = ast_sip_get_transport_states())) {
return PJ_SUCCESS;
}
if (!(transport_state = ao2_callback(transport_states, 0, find_transport_state_in_use, &details))) {
return PJ_SUCCESS;
}
if (!(transport = ast_sorcery_retrieve_by_id(ast_sip_get_sorcery(), "transport", transport_state->id))) {
return PJ_SUCCESS;
}
if (transport_state->localnet) {
ast_sockaddr_parse(&addr, tdata->tp_info.dst_name, PARSE_PORT_FORBID);
ast_sockaddr_set_port(&addr, tdata->tp_info.dst_port);
/* See if where we are sending this request is local or not, and if not that we can get a Contact URI to modify */
if (ast_sip_transport_is_local(transport_state, &addr)) {
ast_debug(5, "Request is being sent to local address, skipping NAT manipulation\n");
return PJ_SUCCESS;
}
}
if (!ast_sockaddr_isnull(&transport_state->external_signaling_address)) {
pjsip_cseq_hdr *cseq = PJSIP_MSG_CSEQ_HDR(tdata->msg);
/* Update the Contact header with the external address. We only do this if
* a CSeq is not present (which should not happen - but we are extra safe),
* if a request is being sent, or if a response is sent that is not a response
* to a REGISTER. We specifically don't do this for a response to a REGISTER
* as the Contact headers would contain the registered Contacts, and not our
* own Contact.
*/
if (!cseq || tdata->msg->type == PJSIP_REQUEST_MSG ||
pjsip_method_cmp(&cseq->method, &pjsip_register_method)) {
/* We can only rewrite the URI when one is present */
if (uri || (uri = nat_get_contact_sip_uri(tdata))) {
pj_strdup2(tdata->pool, &uri->host, ast_sockaddr_stringify_host(&transport_state->external_signaling_address));
if (transport->external_signaling_port) {
uri->port = transport->external_signaling_port;
ast_debug(4, "Re-wrote Contact URI port to %d\n", uri->port);
}
}
}
/* Update the via header if relevant */
if ((tdata->msg->type == PJSIP_REQUEST_MSG) && (via || (via = pjsip_msg_find_hdr(tdata->msg, PJSIP_H_VIA, NULL)))) {
pj_strdup2(tdata->pool, &via->sent_by.host, ast_sockaddr_stringify_host(&transport_state->external_signaling_address));
if (transport->external_signaling_port) {
via->sent_by.port = transport->external_signaling_port;
}
}
}
/* Invoke any additional hooks that may be registered */
if ((hooks = ast_sorcery_retrieve_by_fields(ast_sip_get_sorcery(), "nat_hook", AST_RETRIEVE_FLAG_MULTIPLE | AST_RETRIEVE_FLAG_ALL, NULL))) {
struct nat_hook_details hook_details = {
.tdata = tdata,
.transport = transport,
};
ao2_callback(hooks, 0, nat_invoke_hook, &hook_details);
}
return PJ_SUCCESS;
}
static pj_status_t nat_on_tx_message(pjsip_tx_data *tdata) {
pj_status_t rc;
rc = process_nat(tdata);
restore_orig_contact_host(tdata);
return rc;
}
static pjsip_module nat_module = {
.name = { "NAT", 3 },
.id = -1,
.priority = PJSIP_MOD_PRIORITY_TSX_LAYER - 2,
.on_rx_request = nat_on_rx_message,
.on_rx_response = nat_on_rx_message,
.on_tx_request = nat_on_tx_message,
.on_tx_response = nat_on_tx_message,
};
/*! \brief Function called when an INVITE goes out */
static int nat_incoming_invite_request(struct ast_sip_session *session, struct pjsip_rx_data *rdata)
{
if (session->inv_session->state == PJSIP_INV_STATE_INCOMING) {
pjsip_dlg_add_usage(session->inv_session->dlg, &nat_module, NULL);
}
return 0;
}
/*! \brief Function called when an INVITE response comes in */
static void nat_incoming_invite_response(struct ast_sip_session *session, struct pjsip_rx_data *rdata)
{
handle_rx_message(session->endpoint, rdata);
}
/*! \brief Function called when an INVITE comes in */
static void nat_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, &nat_module, NULL);
}
}
/*! \brief Supplement for adding NAT functionality to dialog */
static struct ast_sip_session_supplement nat_supplement = {
.method = "INVITE",
.priority = AST_SIP_SUPPLEMENT_PRIORITY_FIRST + 1,
.incoming_request = nat_incoming_invite_request,
.outgoing_request = nat_outgoing_invite_request,
.incoming_response = nat_incoming_invite_response,
};
static int unload_module(void)
{
ast_sip_session_unregister_supplement(&nat_supplement);
ast_sip_unregister_service(&nat_module);
return 0;
}
static int load_module(void)
{
if (ast_sip_register_service(&nat_module)) {
ast_log(LOG_ERROR, "Could not register NAT module for incoming and outgoing requests\n");
return AST_MODULE_LOAD_DECLINE;
}
ast_sip_session_register_supplement(&nat_supplement);
return AST_MODULE_LOAD_SUCCESS;
}
AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "PJSIP NAT Support",
.support_level = AST_MODULE_SUPPORT_CORE,
.load = load_module,
.unload = unload_module,
.load_pri = AST_MODPRI_APP_DEPEND,
.requires = "res_pjsip,res_pjsip_session",
);