path: root/lib/ext/cert_type.c

/*
 * Copyright (C) 2002-2012 Free Software Foundation, Inc.
 *
 * Author: Nikos Mavrogiannopoulos
 *
 * This file is part of GnuTLS.
 *
 * The GnuTLS 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 program.  If not, see <http://www.gnu.org/licenses/>
 *
 */

/* This file contains the code the Certificate Type TLS extension.
 * This extension is currently gnutls specific.
 */

#include "gnutls_int.h"
#include "gnutls_errors.h"
#include "gnutls_num.h"
#include <ext/cert_type.h>
#include <gnutls_state.h>
#include <gnutls_num.h>

/* Maps record size to numbers according to the
 * extensions draft.
 */
inline static int _gnutls_num2cert_type (int num);
inline static int _gnutls_cert_type2num (int record_size);
static int _gnutls_cert_type_recv_params (gnutls_session_t session,
                                          const uint8_t * data,
                                          size_t data_size);
static int _gnutls_cert_type_send_params (gnutls_session_t session,
                                          gnutls_buffer_st * extdata);

extension_entry_st ext_mod_cert_type = {
  .name = "CERT TYPE",
  .type = GNUTLS_EXTENSION_CERT_TYPE,
  .parse_type = GNUTLS_EXT_TLS,

  .recv_func = _gnutls_cert_type_recv_params,
  .send_func = _gnutls_cert_type_send_params,
  .pack_func = NULL,
  .unpack_func = NULL,
  .deinit_func = NULL
};

/* 
 * In case of a server: if a CERT_TYPE extension type is received then it stores
 * into the session security parameters the new value. The server may use gnutls_session_certificate_type_get(),
 * to access it.
 *
 * In case of a client: If a cert_types have been specified then we send the extension.
 *
 */

static int
_gnutls_cert_type_recv_params (gnutls_session_t session,
                               const uint8_t * data, size_t _data_size)
{
  int new_type = -1, ret, i;
  ssize_t data_size = _data_size;

  if (session->security_parameters.entity == GNUTLS_CLIENT)
    {
      if (data_size > 0)
        {
          if (data_size != 1)
            {
              gnutls_assert ();
              return GNUTLS_E_UNEXPECTED_PACKET_LENGTH;
            }

          new_type = _gnutls_num2cert_type (data[0]);

          if (new_type < 0)
            {
              gnutls_assert ();
              return new_type;
            }

          /* Check if we support this cert_type */
          if ((ret =
               _gnutls_session_cert_type_supported (session, new_type)) < 0)
            {
              gnutls_assert ();
              return ret;
            }

          _gnutls_session_cert_type_set (session, new_type);
        }
    }
  else
    {                           /* SERVER SIDE - we must check if the sent cert type is the right one 
                                 */
      if (data_size > 1)
        {
          uint8_t len;

          DECR_LEN (data_size, 1);
          len = data[0];
          DECR_LEN (data_size, len);

          for (i = 0; i < len; i++)
            {
              new_type = _gnutls_num2cert_type (data[i + 1]);

              if (new_type < 0)
                continue;

              /* Check if we support this cert_type */
              if ((ret =
                   _gnutls_session_cert_type_supported (session,
                                                        new_type)) < 0)
                {
                  gnutls_assert ();
                  continue;
                }
              else
                break;
              /* new_type is ok */
            }

          if (new_type < 0)
            {
              gnutls_assert ();
              return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
            }

          if ((ret =
               _gnutls_session_cert_type_supported (session, new_type)) < 0)
            {
              gnutls_assert ();
              /* The peer has requested unsupported certificate
               * types. Instead of failing, procceed normally.
               * (the ciphersuite selection would fail, or a
               * non certificate ciphersuite will be selected).
               */
              return 0;
            }

          _gnutls_session_cert_type_set (session, new_type);
        }
    }

  return 0;
}

/* returns data_size or a negative number on failure
 */
static int
_gnutls_cert_type_send_params (gnutls_session_t session, gnutls_buffer_st* extdata)
{
  unsigned len, i;
  int ret;
  uint8_t p;
  
  /* this function sends the client extension data (dnsname) */
  if (session->security_parameters.entity == GNUTLS_CLIENT)
    {

      if (session->internals.priorities.cert_type.algorithms > 0)
        {

          len = session->internals.priorities.cert_type.algorithms;

          if (len == 1 &&
              session->internals.priorities.cert_type.priority[0] ==
              GNUTLS_CRT_X509)
            {
              /* We don't use this extension if X.509 certificates
               * are used.
               */
              return 0;
            }

          /* this is a vector!
           */
          p = (uint8_t) len;
          ret = _gnutls_buffer_append_data(extdata, &p, 1);
          if (ret < 0)
            return gnutls_assert_val(ret);

          for (i = 0; i < len; i++)
            {
              p =
                _gnutls_cert_type2num (session->internals.priorities.
                                       cert_type.priority[i]);
              ret = _gnutls_buffer_append_data(extdata, &p, 1);
              if (ret < 0)
                return gnutls_assert_val(ret);
            }
          return len + 1;
        }

    }
  else
    {                           /* server side */
      if (session->security_parameters.cert_type != DEFAULT_CERT_TYPE)
        {
          len = 1;

          p =
            _gnutls_cert_type2num (session->security_parameters.cert_type);
          ret = _gnutls_buffer_append_data(extdata, &p, 1);
          if (ret < 0)
            return gnutls_assert_val(ret);

          return len;
        }


    }

  return 0;
}

/* Maps numbers to record sizes according to the
 * extensions draft.
 */
inline static int
_gnutls_num2cert_type (int num)
{
  switch (num)
    {
    case 0:
      return GNUTLS_CRT_X509;
    case 1:
      return GNUTLS_CRT_OPENPGP;
    default:
      return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
    }
}

/* Maps record size to numbers according to the
 * extensions draft.
 */
inline static int
_gnutls_cert_type2num (int cert_type)
{
  switch (cert_type)
    {
    case GNUTLS_CRT_X509:
      return 0;
    case GNUTLS_CRT_OPENPGP:
      return 1;
    default:
      return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
    }

}