/*

 * Copyright (C) 2015-2016 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/>

 *

 */

/* Functions that relate to the TLS handshake procedure.

 */

#include "gnutls_int.h"

#include "errors.h"

#include "debug.h"

#include "handshake.h"

#include "auth/cert.h"

#include "constate.h"

#include "record.h"

#include "state.h"

#include "ext/safe_renegotiation.h"

#include "auth/anon.h" /* for gnutls_anon_server_credentials_t */

#include "auth/psk.h" /* for gnutls_psk_server_credentials_t */

#ifdef ENABLE_SRP

#include "auth/srp_kx.h"

#endif

int _gnutls_check_id_for_change(gnutls_session_t session)

{

  int cred_type;

  /* This checks in PSK and SRP ciphersuites that the username remained the

   * same on a rehandshake. */

  if (session->internals.flags & GNUTLS_ALLOW_ID_CHANGE)

    return 0;

  cred_type = gnutls_auth_get_type(session);

  if (cred_type == GNUTLS_CRD_PSK || cred_type == GNUTLS_CRD_SRP) {

    const char *username = NULL;

    int username_length;

    if (cred_type == GNUTLS_CRD_PSK) {

      psk_auth_info_t ai;

      ai = _gnutls_get_auth_info(session, GNUTLS_CRD_PSK);

      if (ai == NULL)

        return gnutls_assert_val(

          GNUTLS_E_INTERNAL_ERROR);

      username = ai->username;

      username_length = ai->username_len;

#ifdef ENABLE_SRP

    } else {

      srp_server_auth_info_t ai =

        _gnutls_get_auth_info(session, GNUTLS_CRD_SRP);

      if (ai == NULL)

        return gnutls_assert_val(

          GNUTLS_E_INTERNAL_ERROR);

      username = ai->username;

      username_length = strlen(ai->username);

#endif

    }

    if (username == NULL)

      return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

    if (session->internals.saved_username &&

        session->internals.saved_username_size != -1) {

      if (session->internals.saved_username_size ==

            username_length &&

          strncmp(session->internals.saved_username, username,

            username_length)) {

        _gnutls_debug_log(

          "Session's PSK username changed during rehandshake; aborting!\n");

        return gnutls_assert_val(

          GNUTLS_E_SESSION_USER_ID_CHANGED);

      }

    } else if (session->internals.saved_username == NULL &&

         session->internals.saved_username_size == -1) {

      if (username_length > MAX_USERNAME_SIZE)

        return gnutls_assert_val(

          GNUTLS_E_INTERNAL_ERROR);

      char *tmp = gnutls_malloc(username_length + 1);

      if (tmp == NULL)

        return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

      memcpy(tmp, username, username_length);

      tmp[username_length] = '\0';

      session->internals.saved_username = tmp;

      session->internals.saved_username_size =

        username_length;

    } else

      return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

  }

  return 0;

}

int _gnutls_check_if_cert_hash_is_same(gnutls_session_t session,

               gnutls_certificate_credentials_t cred)

{

  cert_auth_info_t ai;

  char tmp[32];

  int ret;

  if (session->internals.flags & GNUTLS_ALLOW_ID_CHANGE)

    return 0;

  ai = _gnutls_get_auth_info(session, GNUTLS_CRD_CERTIFICATE);

  if (ai == NULL || ai->ncerts == 0)

    return 0;

  ret = gnutls_hash_fast(GNUTLS_DIG_SHA256,

             ai->raw_certificate_list[0].data,

             ai->raw_certificate_list[0].size, tmp);

  if (ret < 0)

    return gnutls_assert_val(ret);

  if (session->internals.cert_hash_set) {

    if (memcmp(tmp, session->internals.cert_hash, 32) != 0) {

      _gnutls_debug_log(

        "Session certificate changed during rehandshake; aborting!\n");

      return gnutls_assert_val(

        GNUTLS_E_SESSION_USER_ID_CHANGED);

    }

  } else {

    memcpy(session->internals.cert_hash, tmp, 32);

    session->internals.cert_hash_set = 1;

  }

  return 0;

}