/*

 * Copyright (C) 2017 Red Hat, 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 <https://www.gnu.org/licenses/>

 *

 */

#include "gnutls_int.h"

#include "errors.h"

#include "hello_ext.h"

#include "handshake.h"

#include "tls13/hello_retry.h"

#include "auth/cert.h"

#include "mbuffers.h"

#include "state.h"

int _gnutls13_send_hello_retry_request(gnutls_session_t session, unsigned again)

{

  int ret;

  mbuffer_st *bufel = NULL;

  gnutls_buffer_st buf;

  const version_entry_st *ver;

  const uint8_t vbuf[2] = { 0x03, 0x03 };

  if (again == 0) {

    ver = get_version(session);

    if (unlikely(ver == NULL ||

           session->security_parameters.cs == NULL))

      return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

    ret = _gnutls_buffer_init_handshake_mbuffer(&buf);

    if (ret < 0)

      return gnutls_assert_val(ret);

    ret = _gnutls_buffer_append_data(&buf, vbuf, 2);

    if (ret < 0)

      return gnutls_assert_val(ret);

    ret = _gnutls_buffer_append_data(&buf, HRR_RANDOM,

             GNUTLS_RANDOM_SIZE);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    ret = _gnutls_buffer_append_data_prefix(

      &buf, 8, session->security_parameters.session_id,

      session->security_parameters.session_id_size);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    ret = _gnutls_buffer_append_data(

      &buf, session->security_parameters.cs->id, 2);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    /* compression */

    ret = _gnutls_buffer_append_prefix(&buf, 8, 0);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    ret = _gnutls_gen_hello_extensions(

      session, &buf, GNUTLS_EXT_FLAG_HRR, GNUTLS_EXT_ANY);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    /* reset extensions sent by this session to allow re-sending them */

    session->internals.used_exts = 0;

    reset_binders(session);

    bufel = _gnutls_buffer_to_mbuffer(&buf);

  }

  return _gnutls_send_handshake(session, bufel,

              GNUTLS_HANDSHAKE_HELLO_RETRY_REQUEST);

cleanup:

  _gnutls_buffer_clear(&buf);

  return ret;

}

int _gnutls13_recv_hello_retry_request(gnutls_session_t session,

               gnutls_buffer_st *buf)

{

  int ret;

  uint8_t tmp[2];

  const gnutls_cipher_suite_entry_st *cs;

  const mac_entry_st *prf;

  gnutls_datum_t session_id;

  uint8_t random[GNUTLS_RANDOM_SIZE];

  /* only under TLS 1.3 */

  if (IS_DTLS(session))

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET);

  if (session->internals.hsk_flags & HSK_HRR_RECEIVED)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET);

  session->internals.hsk_flags |= HSK_HRR_RECEIVED;

  /* version */

  ret = _gnutls_buffer_pop_data(buf, tmp, 2);

  if (ret < 0)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  if (unlikely(tmp[0] != 0x03 || tmp[1] != 0x03))

    return gnutls_assert_val(GNUTLS_E_UNSUPPORTED_VERSION_PACKET);

  ret = _gnutls_buffer_pop_data(buf, random, GNUTLS_RANDOM_SIZE);

  if (ret < 0)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  if (memcmp(random, HRR_RANDOM, GNUTLS_RANDOM_SIZE) != 0) {

    return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);

  }

  ret = _gnutls_buffer_pop_datum_prefix8(buf, &session_id);

  if (ret < 0)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  /* read ciphersuites */

  ret = _gnutls_buffer_pop_data(buf, tmp, 2);

  if (ret < 0)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  cs = ciphersuite_to_entry(tmp);

  if (unlikely(cs == NULL))

    return gnutls_assert_val(GNUTLS_E_UNKNOWN_CIPHER_SUITE);

  _gnutls_handshake_log("EXT[%p]: Hello Retry Request with %s\n", session,

            cs->name);

  memcpy(session->internals.hrr_cs, cs->id, 2);

  prf = mac_to_entry(cs->prf);

  if (unlikely(prf == NULL))

    return gnutls_assert_val(GNUTLS_E_UNKNOWN_CIPHER_SUITE);

  /* compression */

  ret = _gnutls_buffer_pop_data(buf, tmp, 1);

  if (ret < 0)

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);

  if (unlikely(tmp[0] != 0))

    return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);

  ret = _gnutls13_handshake_hash_buffers_synth(session, prf, 1);

  if (ret < 0)

    return gnutls_assert_val(ret);

  if (buf->length <= 2) {

    /* no extensions present */

    return gnutls_assert_val(GNUTLS_E_UNEXPECTED_EXTENSIONS_LENGTH);

  }

  /* figure version first */

  ret = _gnutls_parse_hello_extensions(session, GNUTLS_EXT_FLAG_HRR,

               GNUTLS_EXT_VERSION_NEG, buf->data,

               buf->length);

  if (ret < 0)

    return gnutls_assert_val(ret);

  /* parse the rest of extensions */

  ret = _gnutls_parse_hello_extensions(session, GNUTLS_EXT_FLAG_HRR,

               GNUTLS_EXT_ANY, buf->data,

               buf->length);

  if (ret < 0)

    return gnutls_assert_val(ret);

  session->internals.used_exts = 0;

  return 0;

}