/*

 * Copyright (C) 2013 Nikos Mavrogiannopoulos

 * Copyright (C) 2017 Red Hat, Inc.

 * 

 * 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 <https://www.gnu.org/licenses/>

 *

 */

#include "gnutls_int.h"

#include "auth.h"

#include "errors.h"

#include "num.h"

#include "ext/alpn.h"

static int _gnutls_alpn_recv_params(gnutls_session_t session,

            const uint8_t *data, size_t data_size);

static int _gnutls_alpn_send_params(gnutls_session_t session,

            gnutls_buffer_st *extdata);

static void _gnutls_alpn_deinit_data(gnutls_ext_priv_data_t priv);

const hello_ext_entry_st ext_mod_alpn = {

  .name = "ALPN",

  .tls_id = 16,

  .gid = GNUTLS_EXTENSION_ALPN,

  /* this extension must be parsed even on resumption */

  .client_parse_point = GNUTLS_EXT_MANDATORY,

  .server_parse_point = GNUTLS_EXT_MANDATORY,

  .validity = GNUTLS_EXT_FLAG_TLS | GNUTLS_EXT_FLAG_DTLS |

        GNUTLS_EXT_FLAG_CLIENT_HELLO | GNUTLS_EXT_FLAG_EE |

        GNUTLS_EXT_FLAG_TLS12_SERVER_HELLO,

  .recv_func = _gnutls_alpn_recv_params,

  .send_func = _gnutls_alpn_send_params,

  .deinit_func = _gnutls_alpn_deinit_data,

  .cannot_be_overriden = 1

};

static int _gnutls_alpn_recv_params(gnutls_session_t session,

            const uint8_t *data, size_t data_size)

{

  unsigned int i;

  int ret;

  const uint8_t *p = data;

  unsigned len1, len;

  alpn_ext_st *priv;

  gnutls_ext_priv_data_t epriv;

  int selected_protocol_index;

  ret = _gnutls_hello_ext_get_priv(session, GNUTLS_EXTENSION_ALPN,

           &epriv);

  if (ret < 0)

    return 0;

  priv = epriv;

  DECR_LENGTH_RET(data_size, 2, GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  len = _gnutls_read_uint16(p);

  p += 2;

  if (len == 0 || len > (size_t)data_size)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  if (session->security_parameters.entity == GNUTLS_SERVER) {

    selected_protocol_index = MAX_ALPN_PROTOCOLS + 1;

    while (data_size > 0) {

      DECR_LENGTH_RET(data_size, 1,

          GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

      len1 = *p;

      p += 1;

      DECR_LENGTH_RET(data_size, len1,

          GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

      if (len1 == 0)

        return gnutls_assert_val(

          GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

      for (i = 0; i < priv->size; i++) {

        if (priv->protocol_size[i] == len1 &&

            memcmp(p, priv->protocols[i], len1) == 0) {

          if (priv->flags &

              GNUTLS_ALPN_SERVER_PRECEDENCE) {

            if (selected_protocol_index >

                (int)i) {

              selected_protocol_index =

                i;

              priv->selected_protocol =

                priv->protocols

                  [i];

              priv->selected_protocol_size =

                priv->protocol_size

                  [i];

              break;

            }

          } else {

            priv->selected_protocol =

              priv->protocols[i];

            priv->selected_protocol_size =

              priv->protocol_size[i];

            return 0;

          }

        }

      }

      p += len1;

    }

  } else {

    DECR_LENGTH_RET(data_size, 1,

        GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

    len1 = *p;

    p += 1;

    DECR_LENGTH_RET(data_size, len1,

        GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

    for (i = 0; i < priv->size; i++) {

      if (priv->protocol_size[i] == len1 &&

          memcmp(p, priv->protocols[i], len1) == 0) {

        priv->selected_protocol = priv->protocols[i];

        priv->selected_protocol_size =

          priv->protocol_size[i];

        break;

      }

    }

    /*p += len1; */

  }

  if (priv->selected_protocol == NULL && (priv->flags & GNUTLS_ALPN_MAND))

    return gnutls_assert_val(GNUTLS_E_NO_APPLICATION_PROTOCOL);

  return 0;

}

static int _gnutls_alpn_send_params(gnutls_session_t session,

            gnutls_buffer_st *extdata)

{

  unsigned i;

  int total_size = 0, ret;

  alpn_ext_st *priv;

  gnutls_ext_priv_data_t epriv;

  ret = _gnutls_hello_ext_get_priv(session, GNUTLS_EXTENSION_ALPN,

           &epriv);

  if (ret < 0)

    return 0;

  priv = epriv;

  if (priv->size == 0)

    return 0;

  if (session->security_parameters.entity == GNUTLS_SERVER) {

    if (priv->selected_protocol_size == 0)

      return 0;

    ret = _gnutls_buffer_append_prefix(

      extdata, 16, priv->selected_protocol_size + 1);

    if (ret < 0)

      return gnutls_assert_val(ret);

    total_size += 2;

    ret = _gnutls_buffer_append_data_prefix(

      extdata, 8, priv->selected_protocol,

      priv->selected_protocol_size);

    if (ret < 0)

      return gnutls_assert_val(ret);

    total_size += 1 + priv->selected_protocol_size;

  } else {

    int t = 0;

    for (i = 0; i < priv->size; i++)

      t += priv->protocol_size[i] + 1;

    ret = _gnutls_buffer_append_prefix(extdata, 16, t);

    if (ret < 0)

      return gnutls_assert_val(ret);

    total_size += 2;

    for (i = 0; i < priv->size; i++) {

      ret = _gnutls_buffer_append_data_prefix(

        extdata, 8, priv->protocols[i],

        priv->protocol_size[i]);

      if (ret < 0)

        return gnutls_assert_val(ret);

      total_size += 1 + priv->protocol_size[i];

    }

  }

  return total_size;

}

/**

 * gnutls_alpn_get_selected_protocol:

 * @session: is a #gnutls_session_t type.

 * @protocol: will hold the protocol name

 *

 * This function allows you to get the negotiated protocol name. The

 * returned protocol should be treated as opaque, constant value and

 * only valid during the session life.

 *

 * The selected protocol is the first supported by the list sent

 * by the client.

 *

 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,

 *   otherwise a negative error code is returned.

 *

 * Since 3.2.0

 **/

int gnutls_alpn_get_selected_protocol(gnutls_session_t session,

              gnutls_datum_t *protocol)

{

  alpn_ext_st *priv;

  int ret;

  gnutls_ext_priv_data_t epriv;

  ret = _gnutls_hello_ext_get_priv(session, GNUTLS_EXTENSION_ALPN,

           &epriv);

  if (ret < 0) {

    gnutls_assert();

    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;

  }

  priv = epriv;

  if (priv->selected_protocol_size == 0)

    return gnutls_assert_val(GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);

  protocol->data = priv->selected_protocol;

  protocol->size = priv->selected_protocol_size;

  return 0;

}

/**

 * gnutls_alpn_set_protocols:

 * @session: is a #gnutls_session_t type.

 * @protocols: is the protocol names to add.

 * @protocols_size: the number of protocols to add.

 * @flags: zero or a sequence of %gnutls_alpn_flags_t

 *

 * This function is to be used by both clients and servers, to declare

 * the supported ALPN protocols, which are used during negotiation with peer.

 *

 * See %gnutls_alpn_flags_t description for the documentation of available

 * flags.

 *

 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,

 *   otherwise a negative error code is returned.

 *

 * Since 3.2.0

 **/

int gnutls_alpn_set_protocols(gnutls_session_t session,

            const gnutls_datum_t *protocols,

            unsigned protocols_size, unsigned int flags)

{

  int ret;

  alpn_ext_st *priv;

  gnutls_ext_priv_data_t epriv;

  unsigned i;

  ret = _gnutls_hello_ext_get_priv(session, GNUTLS_EXTENSION_ALPN,

           &epriv);

  if (ret < 0) {

    priv = gnutls_calloc(1, sizeof(*priv));

    if (priv == NULL) {

      gnutls_assert();

      return GNUTLS_E_MEMORY_ERROR;

    }

    epriv = priv;

    _gnutls_hello_ext_set_priv(session, GNUTLS_EXTENSION_ALPN,

             epriv);

  } else

    priv = epriv;

  if (protocols_size > MAX_ALPN_PROTOCOLS)

    return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

  for (i = 0; i < protocols_size; i++) {

    if (protocols[i].size >= MAX_ALPN_PROTOCOL_NAME)

      return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

    memcpy(priv->protocols[i], protocols[i].data,

           protocols[i].size);

    priv->protocol_size[i] = protocols[i].size;

    priv->size++;

  }

  priv->flags = flags;

  return 0;

}

static void _gnutls_alpn_deinit_data(gnutls_ext_priv_data_t priv)

{

  gnutls_free(priv);

}