1 files changed, 237 insertions, 0 deletions
diff --git a/res/res_pjsip_nat.c b/res/res_pjsip_nat.c
new file mode 100644
index 000000000..d04505107
--- /dev/null
+++ b/res/res_pjsip_nat.c
@@ -0,0 +1,237 @@
+/*
+ * 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>
+	<support_level>core</support_level>
+ ***/
+
+#include "asterisk.h"
+
+#include <pjsip.h>
+#include <pjsip_ua.h>
+
+#include "asterisk/res_pjsip.h"
+#include "asterisk/module.h"
+#include "asterisk/acl.h"
+
+static pj_bool_t nat_on_rx_request(pjsip_rx_data *rdata)
+{
+	RAII_VAR(struct ast_sip_endpoint *, endpoint, ast_pjsip_rdata_get_endpoint(rdata), ao2_cleanup);
+	pjsip_contact_hdr *contact;
+
+	if (!endpoint) {
+		return PJ_FALSE;
+	}
+
+	if (endpoint->nat.rewrite_contact && (contact = pjsip_msg_find_hdr(rdata->msg_info.msg, PJSIP_H_CONTACT, NULL)) &&
+		(PJSIP_URI_SCHEME_IS_SIP(contact->uri) || PJSIP_URI_SCHEME_IS_SIPS(contact->uri))) {
+		pjsip_sip_uri *uri = pjsip_uri_get_uri(contact->uri);
+
+		pj_cstr(&uri->host, rdata->pkt_info.src_name);
+		uri->port = rdata->pkt_info.src_port;
+	}
+
+	if (endpoint->nat.force_rport) {
+		rdata->msg_info.via->rport_param = 0;
+	}
+
+	return PJ_FALSE;
+}
+
+/*! \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_in_use(void *obj, void *arg, int flags)
+{
+	struct ast_sip_transport *transport = 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 ((details->transport && details->transport == transport->state->transport) ||
+		(details->factory && details->factory == transport->state->factory) ||
+		((details->type == transport->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 | CMP_STOP;
+	}
+
+	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 pj_status_t nat_on_tx_message(pjsip_tx_data *tdata)
+{
+	RAII_VAR(struct ao2_container *, transports, NULL, ao2_cleanup);
+	RAII_VAR(struct ast_sip_transport *, transport, 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 (!(transports = ast_sorcery_retrieve_by_fields(ast_sip_get_sorcery(), "transport", AST_RETRIEVE_FLAG_MULTIPLE | AST_RETRIEVE_FLAG_ALL, NULL)) ||
+		!(transport = ao2_callback(transports, 0, find_transport_in_use, &details)) || !transport->localnet ||
+		ast_sockaddr_isnull(&transport->external_address)) {
+		return PJ_SUCCESS;
+	}
+
+	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_apply_ha(transport->localnet, &addr) != AST_SENSE_ALLOW) {
+		return PJ_SUCCESS;
+	}
+
+	/* Update the contact header with the external address */
+	if (uri || (uri = nat_get_contact_sip_uri(tdata))) {
+		pj_strdup2(tdata->pool, &uri->host, ast_sockaddr_stringify_host(&transport->external_address));
+		if (transport->external_signaling_port) {
+			uri->port = transport->external_signaling_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->external_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 pjsip_module nat_module = {
+	.name = { "NAT", 3 },
+	.id = -1,
+	.priority = PJSIP_MOD_PRIORITY_TSX_LAYER - 2,
+	.on_rx_request = nat_on_rx_request,
+	.on_tx_request = nat_on_tx_message,
+	.on_tx_response = nat_on_tx_message,
+};
+
+static int load_module(void)
+{
+	ast_sip_register_service(&nat_module);
+	return AST_MODULE_LOAD_SUCCESS;
+}
+
+static int unload_module(void)
+{
+	ast_sip_unregister_service(&nat_module);
+	return 0;
+}
+
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "PJSIP NAT Support",
+		.load = load_module,
+		.unload = unload_module,
+		.load_pri = AST_MODPRI_APP_DEPEND,
+	       );