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nta_check.c
/*
 * This file is part of the Sofia-SIP package
 *
 * Copyright (C) 2005, 2011 Nokia Corporation.
 *
 * Contact: Pekka Pessi <pekka.pessi@nokia.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 *
 */

/**@CFILE nta_check.c
 * @brief Checks for features, MIME types, session timer.
 *
 * @author Pekka Pessi <Pekka.Pessi@nokia.com>
 *
 * @date Created: Wed Mar  8 16:35:05 EET 2006 ppessi
 */

#include "config.h"

#include <sofia-sip/su_tagarg.h>
#include <sofia-sip/sip_header.h>
#include <sofia-sip/sip_status.h>
#include <sofia-sip/sip_util.h>
#include <sofia-sip/msg_mime.h>
#include <sofia-sip/nta.h>

/* ======================================================================== */
/* Request validation */

static int internal_error(nta_incoming_t *irq)
{
  if (irq)
    nta_incoming_treply(irq, SIP_500_INTERNAL_SERVER_ERROR, TAG_END());
  return 500;
}

/**Check that we support all features which UAC requires.
 *
 * The list of supported features is compared with the list of features
 * required by the UAC. If some features are not listed as supported, return
 * 420. If @a irq is non-NULL, the 420 response message is sent to the
 * client along with list of unsupported features in the @Unsupported
 * header, too.
 *
 * @param   irq incoming transaction object (may be NULL).
 * @param   sip contents of the SIP message
 * @param supported   list of protocol features supported
 * @param tag, value, ... optional list of tagged arguments used
 *                        when responding to the transaction
 *
 * @retval 0 if successful
 * @retval 420 if any of the required features is not supported by UAS
 * @retval 500 if an internal error occurred
 */
00070 int nta_check_required(nta_incoming_t *irq,
                   sip_t const *sip,
                   sip_supported_t const *supported,
                   tag_type_t tag, tag_value_t value, ...)
{
  int status = 0;

  if (sip == NULL)
    return internal_error(irq);

  if (sip->sip_require) {
    su_home_t home[SU_HOME_AUTO_SIZE(512)];
    sip_unsupported_t *us;

    su_home_auto(home, sizeof home);

    us = sip_has_unsupported(home, supported, sip->sip_require);

    if (us) {
      status = 420;
      if (irq) {
      ta_list ta;
      ta_start(ta, tag, value);
      nta_incoming_treply(irq,
                      SIP_420_BAD_EXTENSION,
                      SIPTAG_UNSUPPORTED(us),
                      SIPTAG_SUPPORTED(supported),
                      ta_tags(ta));
      ta_end(ta);
      }
    }

    su_home_deinit(home);
  }

  return status;
}

/** Check that UAC supports all the required features.
 *
 * The list of required features is compared with the features supported by
 * the UAC. If some features are not supported, return 421. If @a irq is
 * non-NULL, the 421 response message is sent to the client, too.
 *
 * @param irq incoming transaction object (may be NULL).
 * @param sip contents of the SIP message
 * @param require   list of required protocol features
 * @param tag, value, ... optional list of tagged arguments used
 *                        when responding to the transaction
 *
 * @retval 0 if successful
 * @retval 421 if any of the required features is not supported by UAC
 * @retval 500 if an internal error occurred
 */
00124 int nta_check_supported(nta_incoming_t *irq,
                  sip_t const *sip,
                  sip_require_t *require,
                  tag_type_t tag, tag_value_t value, ...)
{
  if (sip == NULL)
    return internal_error(irq);

  if (!sip_has_unsupported(NULL, sip->sip_supported, require))
    return 0;

  if (irq) {
    ta_list ta;
    ta_start(ta, tag, value);
    nta_incoming_treply(irq,
                  SIP_421_EXTENSION_REQUIRED,
                  SIPTAG_REQUIRE(require),
                  ta_tags(ta));
    ta_end(ta);
  }

  return 421;
}

/** Check that we allow the request method.
 *
 * The request-method is compared with the list of supported methods in @a
 * allow. If match is found, 0 is is returned. Otherwise, if the
 * request-method is well-known, 405 is returned. If the request-method is
 * unknown, 501 is returned. If @a irq is non-NULL, the 405 or 501 response
 * message is sent to the client, too.
 *
 * @param irq     incoming transaction object (may be NULL).
 * @param sip     contents of the SIP message
 * @param allow   list of allowed methods
 * @param tag, value, ...   optional list of tagged arguments used
 *                          when responding to the transaction
 *
 * @retval 0 if successful
 * @retval 405 is request-method is not allowed
 * @retval 501 if request-method is unknown
 * @retval 500 if an internal error occurred
 */
00167 int nta_check_method(nta_incoming_t *irq,
                 sip_t const *sip,
                 sip_allow_t const *allow,
                 tag_type_t tag, tag_value_t value, ...)
{
  /* Check extensions */
  sip_method_t method;
  char const *name;

  if (sip == NULL || sip->sip_request == NULL)
    return internal_error(irq);

  method = sip->sip_request->rq_method;
  name = sip->sip_request->rq_method_name;

  if (sip_is_allowed(allow, method, name))
    return 0;

  if (irq) {
    ta_list ta;
    ta_start(ta, tag, value);

    if (method != sip_method_unknown)
      /* Well-known method */
      nta_incoming_treply(irq,
                    SIP_405_METHOD_NOT_ALLOWED,
                    SIPTAG_ALLOW(allow),
                    ta_tags(ta));
    else
      /* Completeley unknown method */
      nta_incoming_treply(irq,
                    SIP_501_NOT_IMPLEMENTED,
                    SIPTAG_ALLOW(allow),
                    ta_tags(ta));
    ta_end(ta);
  }

  return method != sip_method_unknown ? 405 : 501;
}

static sip_content_type_t const *application_sdp(void)
{
  static sip_content_type_t *c;

  if (c == NULL)
    c = sip_content_type_make(NULL, "application/sdp");

  return c;
}

/** Check that we understand session content in the request.
 *
 * If there is no @ContentDisposition header or the @ContentDisposition
 * header indicated "session", the message body and content-type is compared
 * with the acceptable session content-types listed in @a session_accepts.
 * (typically, @c "application/sdp"). If no match is found, a 415 is
 * returned. If @a irq is non-NULL, the 415 response message is sent to the
 * client, too.
 *
 * If the @ContentDisposition header indicates something else but "session",
 * and it does not contain "handling=optional" parameter, a 415 response is
 * returned, too.
 *
 * Also, the @ContentEncoding header is checked. If it is not empty
 * (indicating no content-encoding), a 415 response is returned, too.
 *
 * @param irq     incoming (server) transaction object (may be NULL).
 * @param sip     contents of the SIP message
 * @param session_accepts   list of acceptable content-types for "session"
 *                          content disposition
 * @param tag, value, ...   optional list of tagged arguments used
 *                          when responding to the transaction
 *
 * @retval 0 if successful
 * @retval 415 if Content-Type is not acceptable
 * @retval 500 if an internal error occurred
 */
00244 int nta_check_session_content(nta_incoming_t *irq,
                        sip_t const *sip,
                        sip_accept_t const *session_accepts,
                        tag_type_t tag, tag_value_t value, ...)
{
  sip_content_disposition_t const *cd;
  int acceptable_type = 0, acceptable_encoding = 0;

  if (sip == NULL)
    return internal_error(irq);

  if (sip->sip_payload == NULL && sip->sip_multipart == NULL)
    return 0;

  cd = sip->sip_content_disposition;

  if (cd == NULL || su_casematch(cd->cd_type, "session")) {
    sip_content_type_t const *c = sip->sip_content_type;

    if (c == NULL &&
      sip->sip_payload->pl_len > 3 &&
      su_casenmatch(sip->sip_payload->pl_data, "v=0", 3))
      /* Missing Content-Type, but it looks like SDP  */
      c = application_sdp();

    if (msg_accept_match((msg_accept_t *)session_accepts, c))
      acceptable_type = 1;
  }
  else if (cd->cd_optional)
    acceptable_type = 1;

  /* Empty or missing Content-Encoding */
  if (!sip->sip_content_encoding ||
      !sip->sip_content_encoding->k_items ||
      !sip->sip_content_encoding->k_items[0] ||
      !sip->sip_content_encoding->k_items[0][0])
    acceptable_encoding = 1;

  if (acceptable_type && acceptable_encoding)
    return 0;

  if (irq) {
    ta_list ta;
    ta_start(ta, tag, value);
    nta_incoming_treply(irq,
                  SIP_415_UNSUPPORTED_MEDIA,
                  SIPTAG_ACCEPT(session_accepts),
                  ta_tags(ta));
    ta_end(ta);
  }

  return 415;
}


/**Check that UAC accepts one of listed MIME content-types.
 *
 * The list of acceptable content-types are compared with the acceptable
 * content-types. If match is found, it is returned in @a return_acceptable.
 * If no match is found, a 406 is returned. If @a irq is non-NULL, the 406
 * response message is sent to the client, too.
 *
 * @param irq incoming transaction object (may be NULL).
 * @param sip contents of the SIP message
 * @param acceptable list of acceptable content types
 * @param return_acceptable optional return-value parameter for
 *                          matched content-type
 * @param tag, value, ... optional list of tagged arguments used
 *                        when responding to the transaction
 *
 * @retval 0 if successful
 * @retval 406 if no supported Content-Type is acceptable by client
 * @retval 500 if an internal error occurred
 *
 * @note
 * From @VERSION_UNRELEASED onwards, checks for wildcards, too.
 */
00321 int nta_check_accept(nta_incoming_t *irq,
                 sip_t const *sip,
                 sip_accept_t const *acceptable,
                 sip_accept_t const **return_acceptable,
                 tag_type_t tag, tag_value_t value, ...)
{
  ta_list ta;
  sip_accept_t const *ac, *ab;
  sip_method_t method;

  if (sip == NULL || (sip->sip_request == NULL && sip->sip_cseq == NULL))
    return internal_error(irq);

  if (!acceptable)
    return 0;

  if (sip->sip_request)
    method = sip->sip_request->rq_method;
  else /* if (sip->sip_cseq) */
    method = sip->sip_cseq->cs_method;

  /*
   * Missing Accept header implies support for SDP in INVITE and OPTIONS
   * (and PRACK and UPDATE?)
   */
  if (!sip->sip_accept && (method == sip_method_invite ||
                     method == sip_method_options ||
                     method == sip_method_prack ||
                     method == sip_method_update)) {
    ab = (void *)msg_accept_match((void *)acceptable, application_sdp());
    if (ab) {
      if (return_acceptable) *return_acceptable = ab;
      return 0;
    }
  }

  for (ac = sip->sip_accept; ac; ac = ac->ac_next) {
    if (msg_q_value(ac->ac_q) == 0 || !ac->ac_type)
      continue;

    if (su_strmatch(ac->ac_type, "*/*")) {
      ab = acceptable;
    }
    else if (su_strmatch(ac->ac_subtype, "*")) {
      for (ab = acceptable; ab; ab = ab->ac_next) {
      if (su_casenmatch(ab->ac_type, ac->ac_type,
                    ac->ac_subtype - ac->ac_type))
        break;
      }
    }
    else {
      ab = (void *)msg_accept_match((void *)acceptable,
                            (msg_content_type_t *)ac);
    }

    if (ab) {
      if (return_acceptable) *return_acceptable = ab;
      return 0;
    }
  }

  if (irq) {
    ta_start(ta, tag, value);
    nta_incoming_treply(irq,
                  SIP_406_NOT_ACCEPTABLE,
                  SIPTAG_ACCEPT(acceptable),
                  ta_tags(ta));
    ta_end(ta);
  }

  return 406;
}

/**Check @SessionExpires header.
 *
 * If the proposed session-expiration time is smaller than @MinSE or our
 * minimal session expiration time, respond with 422 containing shortest
 * acceptable session expiration time in @MinSE header.
 *
 * @param irq     incoming transaction object (may be NULL).
 * @param sip     contents of the SIP message
 * @param my_min_se   minimal session expiration time in seconds
 * @param tag, value, ...   optional list of tagged arguments used
 *                          when responding to the transaction
 *
 * @retval 0 when successful
 * @retval 422 if session expiration time is too small
 * @retval 500 if an internal error occurred
 */
00410 int nta_check_session_expires(nta_incoming_t *irq,
                        sip_t const *sip,
                        sip_time_t my_min_se,
                        tag_type_t tag, tag_value_t value, ...)
{
  unsigned long min_se = my_min_se;

  if (sip == NULL)
    return internal_error(irq);

  if (sip->sip_session_expires == NULL)
    return 0;

  if (sip->sip_min_se && min_se < sip->sip_min_se->min_delta)
    min_se = sip->sip_min_se->min_delta;

  if (sip->sip_session_expires->x_delta >= min_se)
    return 0;

  if (irq) {
    ta_list ta;
    sip_min_se_t min_se0[1];

    ta_start(ta, tag, value);

    sip_min_se_init(min_se0)->min_delta = min_se;

    nta_incoming_treply(irq,
                  SIP_422_SESSION_TIMER_TOO_SMALL,
                  SIPTAG_MIN_SE(min_se0),
                  ta_tags(ta));
    ta_end(ta);
  }

  return 422;
}

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