res_pjsip_path.c

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

/*** 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/strings.h"

static const pj_str_t PATH_NAME = { "Path", 4 };
static pj_str_t PATH_SUPPORTED_NAME = { "path", 4 };

static struct ast_sip_aor *find_aor(struct ast_sip_endpoint *endpoint, pjsip_uri *uri)
{
   char *configured_aors, *aor_name;
   pjsip_sip_uri *sip_uri;
   char *domain_name;
   char *username;
   struct ast_str *id = NULL;

   if (ast_strlen_zero(endpoint->aors)) {
      return NULL;
   }

   sip_uri = pjsip_uri_get_uri(uri);
   domain_name = ast_alloca(sip_uri->host.slen + 1);
   ast_copy_pj_str(domain_name, &sip_uri->host, sip_uri->host.slen + 1);
   username = ast_alloca(sip_uri->user.slen + 1);
   ast_copy_pj_str(username, &sip_uri->user, sip_uri->user.slen + 1);

   /*
    * We may want to match without any user options getting
    * in the way.
    */
   AST_SIP_USER_OPTIONS_TRUNCATE_CHECK(username);

   configured_aors = ast_strdupa(endpoint->aors);

   /* Iterate the configured AORs to see if the user or the user+domain match */
   while ((aor_name = ast_strip(strsep(&configured_aors, ",")))) {
      struct ast_sip_domain_alias *alias = NULL;

      if (ast_strlen_zero(aor_name)) {
         continue;
      }

      if (!strcmp(username, aor_name)) {
         break;
      }

      if (!id && !(id = ast_str_create(strlen(username) + sip_uri->host.slen + 2))) {
         aor_name = NULL;
         break;
      }

      ast_str_set(&id, 0, "%s@", username);
      if ((alias = ast_sorcery_retrieve_by_id(ast_sip_get_sorcery(), "domain_alias", domain_name))) {
         ast_str_append(&id, 0, "%s", alias->domain);
         ao2_cleanup(alias);
      } else {
         ast_str_append(&id, 0, "%s", domain_name);
      }

      if (!strcmp(aor_name, ast_str_buffer(id))) {
         break;
      }
   }
   ast_free(id);

   if (ast_strlen_zero(aor_name)) {
      return NULL;
   }

   return ast_sip_location_retrieve_aor(aor_name);
}

/*!
 * \brief Get the path string associated with this contact and tdata
 *
 * \param endpoint The endpoint from which to pull associated path data
 * \param contact_uri The URI identifying the associated contact
 * \param path_str The place to store the retrieved path information
 *
 * \retval zero on success
 * \retval non-zero on failure or no available path information
 */
static int path_get_string(pj_pool_t *pool, struct ast_sip_contact *contact, pj_str_t *path_str)
{
   if (!contact || ast_strlen_zero(contact->path)) {
      return -1;
   }

   *path_str = pj_strdup3(pool, contact->path);
   return 0;
}

static int add_supported(pjsip_tx_data *tdata)
{
   pjsip_supported_hdr *hdr;
   int i;

   hdr = pjsip_msg_find_hdr(tdata->msg, PJSIP_H_SUPPORTED, NULL);
   if (!hdr) {
      /* insert a new Supported header */
      hdr = pjsip_supported_hdr_create(tdata->pool);
      if (!hdr) {
         return -1;
      }

      pjsip_msg_add_hdr(tdata->msg, (pjsip_hdr *)hdr);
   }

   /* Don't add the value if it's already there */
   for (i = 0; i < hdr->count; ++i) {
      if (pj_stricmp(&hdr->values[i], &PATH_SUPPORTED_NAME) == 0) {
         return 0;
      }
   }

   if (hdr->count >= PJSIP_GENERIC_ARRAY_MAX_COUNT) {
      return -1;
   }

   /* add on to the existing Supported header */
   pj_strassign(&hdr->values[hdr->count++], &PATH_SUPPORTED_NAME);

   return 0;
}

/*!
 * \internal
 * \brief Adds a Route header to an outgoing request if
 * path information is available.
 *
 * \param endpoint The endpoint with which this request is associated
 * \param contact The contact to which this request is being sent
 * \param tdata The outbound request
 */
static void path_outgoing_request(struct ast_sip_endpoint *endpoint, struct ast_sip_contact *contact, pjsip_tx_data *tdata)
{
   RAII_VAR(struct ast_sip_aor *, aor, NULL, ao2_cleanup);

   if (!endpoint) {
      return;
   }

   aor = find_aor(endpoint, tdata->msg->line.req.uri);
   if (!aor || !aor->support_path) {
      return;
   }

   if (add_supported(tdata)) {
      return;
   }

   if (contact && !ast_strlen_zero(contact->path)) {
      ast_sip_set_outbound_proxy(tdata, contact->path);
   }
}

static void path_session_outgoing_request(struct ast_sip_session *session, pjsip_tx_data *tdata)
{
   path_outgoing_request(session->endpoint, session->contact, tdata);
}

/*!
 * \internal
 * \brief Adds a path header to an outgoing 2XX response
 *
 * \param endpoint The endpoint to which the INVITE response is to be sent
 * \param contact The contact to which the INVITE response is to be sent
 * \param tdata The outbound INVITE response
 */
static void path_outgoing_response(struct ast_sip_endpoint *endpoint, struct ast_sip_contact *contact, pjsip_tx_data *tdata)
{
   struct pjsip_status_line status = tdata->msg->line.status;
   pj_str_t path_dup;
   pjsip_generic_string_hdr *path_hdr;
   pjsip_contact_hdr *contact_hdr;
   RAII_VAR(struct ast_sip_aor *, aor, NULL, ao2_cleanup);
   pjsip_cseq_hdr *cseq = pjsip_msg_find_hdr(tdata->msg, PJSIP_H_CSEQ, NULL);
   const pj_str_t REGISTER_METHOD = {"REGISTER", 8};

   if (!endpoint
      || !pj_stristr(&REGISTER_METHOD, &cseq->method.name)
      || !PJSIP_IS_STATUS_IN_CLASS(status.code, 200)) {
      return;
   }

   contact_hdr = pjsip_msg_find_hdr(tdata->msg, PJSIP_H_CONTACT, NULL);
   if (!contact_hdr) {
      return;
   }

   aor = find_aor(endpoint, contact_hdr->uri);
   if (!aor || !aor->support_path || add_supported(tdata)
      || path_get_string(tdata->pool, contact, &path_dup)) {
      return;
   }

   path_hdr = pjsip_generic_string_hdr_create(tdata->pool, &PATH_NAME, &path_dup);
   if (!path_hdr) {
      return;
   }

   pjsip_msg_add_hdr(tdata->msg, (pjsip_hdr*)path_hdr);
}

static void path_session_outgoing_response(struct ast_sip_session *session, pjsip_tx_data *tdata)
{
   path_outgoing_response(session->endpoint, session->contact, tdata);
}

static struct ast_sip_supplement path_supplement = {
   .priority = AST_SIP_SUPPLEMENT_PRIORITY_CHANNEL - 100,
   .outgoing_request = path_outgoing_request,
   .outgoing_response = path_outgoing_response,
};

static struct ast_sip_session_supplement path_session_supplement = {
   .priority = AST_SIP_SUPPLEMENT_PRIORITY_CHANNEL - 100,
   .outgoing_request = path_session_outgoing_request,
   .outgoing_response = path_session_outgoing_response,
};

static int load_module(void)
{
   ast_sip_register_supplement(&path_supplement);
   ast_sip_session_register_supplement(&path_session_supplement);

   return AST_MODULE_LOAD_SUCCESS;
}

static int unload_module(void)
{
   ast_sip_unregister_supplement(&path_supplement);
   ast_sip_session_unregister_supplement(&path_session_supplement);
   return 0;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "PJSIP Path Header 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",
);