/*

 * Copyright (C) 2000-2012 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 <https://www.gnu.org/licenses/>

 *

 */

/* This file contains functions which are wrappers for the key exchange

 * part of TLS. They are called by the handshake functions (gnutls_handshake)

 */

#include "gnutls_int.h"

#include "handshake.h"

#include "kx.h"

#include "dh.h"

#include "errors.h"

#include "algorithms.h"

#include "debug.h"

#include "locks.h"

#include "mpi.h"

#include "state.h"

#include "datum.h"

#include "mbuffers.h"

/* This file contains important thing for the TLS handshake procedure.

 */

#define MASTER_SECRET "master secret"

#define MASTER_SECRET_SIZE (sizeof(MASTER_SECRET) - 1)

#define EXT_MASTER_SECRET "extended master secret"

#define EXT_MASTER_SECRET_SIZE (sizeof(EXT_MASTER_SECRET) - 1)

GNUTLS_STATIC_MUTEX(keylog_mutex);

static FILE *keylog;

static int generate_normal_master(gnutls_session_t session, gnutls_datum_t *,

          int);

int _gnutls_generate_master(gnutls_session_t session, int keep_premaster)

{

  if (!session->internals.resumed)

    return generate_normal_master(session, &session->key.key,

                keep_premaster);

  else if (session->internals.premaster_set) {

    gnutls_datum_t premaster;

    premaster.size =

      sizeof(session->internals.resumed_security_parameters

               .master_secret);

    premaster.data = session->internals.resumed_security_parameters

           .master_secret;

    return generate_normal_master(session, &premaster, 1);

  }

  return 0;

}

/**

 * gnutls_session_get_keylog_function:

 * @session: is #gnutls_session_t type

 *

 * This function will return the callback function set using

 * gnutls_session_set_keylog_function().

 *

 * Returns: The function set or %NULL otherwise.

 *

 * Since: 3.6.13

 */

gnutls_keylog_func

gnutls_session_get_keylog_function(const gnutls_session_t session)

{

  return session->internals.keylog_func;

}

/**

 * gnutls_session_set_keylog_function:

 * @session: is #gnutls_session_t type

 * @func: is the function to be called

 *

 * This function will set a callback to be called when a new secret is

 * derived and installed during handshake.

 *

 * Since: 3.6.13

 */

void gnutls_session_set_keylog_function(gnutls_session_t session,

          gnutls_keylog_func func)

{

  session->internals.keylog_func = func;

}

int _gnutls_call_keylog_func(gnutls_session_t session, const char *label,

           const uint8_t *data, unsigned size)

{

  if (session->internals.keylog_func) {

    gnutls_datum_t secret = { (void *)data, size };

    return session->internals.keylog_func(session, label, &secret);

  }

  return 0;

}

int _gnutls_nss_keylog_func(gnutls_session_t session, const char *label,

          const gnutls_datum_t *secret)

{

  /* ignore subsequent traffic secrets that are calculated from

   * the previous traffic secret

   */

  if (!session->internals.handshake_in_progress)

    return 0;

  _gnutls_nss_keylog_write(session, label, secret->data, secret->size);

  return 0;

}

/* GCC analyzer doesn't like static FILE pointer */

#pragma GCC diagnostic push

#pragma GCC diagnostic ignored "-Wanalyzer-file-leak"

GNUTLS_ONCE(keylog_once);

static void keylog_once_init(void)

{

  const char *keylogfile;

  keylogfile = secure_getenv("SSLKEYLOGFILE");

  if (keylogfile != NULL && *keylogfile != '\0') {

    keylog = fopen(keylogfile, "ae");

    if (keylog == NULL)

      _gnutls_debug_log(

        "unable to open keylog file %s, error %d\n",

        keylogfile, errno);

  }

}

void _gnutls_nss_keylog_write(gnutls_session_t session, const char *label,

            const uint8_t *secret, size_t secret_size)

{

  (void)gnutls_once(&keylog_once, keylog_once_init);

  if (keylog) {

    char client_random_hex[2 * GNUTLS_RANDOM_SIZE + 1];

    char secret_hex[2 * MAX_HASH_SIZE + 1];

    if (gnutls_static_mutex_lock(&keylog_mutex) < 0) {

      return;

    }

    fprintf(keylog, "%s %s %s\n", label,

      _gnutls_bin2hex(

        session->security_parameters.client_random,

        GNUTLS_RANDOM_SIZE, client_random_hex,

        sizeof(client_random_hex), NULL),

      _gnutls_bin2hex(secret, secret_size, secret_hex,

          sizeof(secret_hex), NULL));

    fflush(keylog);

    (void)gnutls_static_mutex_unlock(&keylog_mutex);

  }

}

void _gnutls_nss_keylog_deinit(void)

{

  if (keylog) {

    fclose(keylog);

    keylog = NULL;

  }

}

#pragma GCC diagnostic pop

/* here we generate the TLS Master secret.

 */

static int generate_normal_master(gnutls_session_t session,

          gnutls_datum_t *premaster, int keep_premaster)

{

  int ret = 0;

  char buf[512];

  _gnutls_hard_log("INT: PREMASTER SECRET[%d]: %s\n", premaster->size,

       _gnutls_bin2hex(premaster->data, premaster->size, buf,

           sizeof(buf), NULL));

  _gnutls_hard_log(

    "INT: CLIENT RANDOM[%d]: %s\n", 32,

    _gnutls_bin2hex(session->security_parameters.client_random, 32,

        buf, sizeof(buf), NULL));

  _gnutls_hard_log(

    "INT: SERVER RANDOM[%d]: %s\n", 32,

    _gnutls_bin2hex(session->security_parameters.server_random, 32,

        buf, sizeof(buf), NULL));

  if (session->security_parameters.ext_master_secret == 0) {

    uint8_t rnd[2 * GNUTLS_RANDOM_SIZE + 1];

    memcpy(rnd, session->security_parameters.client_random,

           GNUTLS_RANDOM_SIZE);

    memcpy(&rnd[GNUTLS_RANDOM_SIZE],

           session->security_parameters.server_random,

           GNUTLS_RANDOM_SIZE);

    _gnutls_memory_mark_defined(

      session->security_parameters.master_secret,

      GNUTLS_MASTER_SIZE);

#ifdef ENABLE_SSL3

    if (get_num_version(session) == GNUTLS_SSL3) {

      ret = _gnutls_ssl3_generate_random(

        premaster->data, premaster->size, rnd,

        2 * GNUTLS_RANDOM_SIZE, GNUTLS_MASTER_SIZE,

        session->security_parameters.master_secret);

    } else

#endif

      ret = _gnutls_PRF(

        session, premaster->data, premaster->size,

        MASTER_SECRET, MASTER_SECRET_SIZE, rnd,

        2 * GNUTLS_RANDOM_SIZE, GNUTLS_MASTER_SIZE,

        session->security_parameters.master_secret);

    if (ret < 0)

      _gnutls_memory_mark_undefined(

        session->security_parameters.master_secret,

        GNUTLS_MASTER_SIZE);

  } else {

    gnutls_datum_t shash = { NULL, 0 };

    /* draft-ietf-tls-session-hash-02 */

    ret = _gnutls_handshake_get_session_hash(session, &shash);

    if (ret < 0)

      return gnutls_assert_val(ret);

#ifdef ENABLE_SSL3

    if (get_num_version(session) == GNUTLS_SSL3)

      return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

#endif

    _gnutls_memory_mark_defined(

      session->security_parameters.master_secret,

      GNUTLS_MASTER_SIZE);

    ret = _gnutls_PRF(session, premaster->data, premaster->size,

          EXT_MASTER_SECRET, EXT_MASTER_SECRET_SIZE,

          shash.data, shash.size, GNUTLS_MASTER_SIZE,

          session->security_parameters.master_secret);

    if (ret < 0)

      _gnutls_memory_mark_undefined(

        session->security_parameters.master_secret,

        GNUTLS_MASTER_SIZE);

    gnutls_free(shash.data);

  }

  if (!keep_premaster)

    _gnutls_free_key_datum(premaster);

  if (ret < 0)

    return ret;

  ret = _gnutls_call_keylog_func(

    session, "CLIENT_RANDOM",

    session->security_parameters.master_secret, GNUTLS_MASTER_SIZE);

  if (ret < 0)

    return gnutls_assert_val(ret);

  _gnutls_hard_log(

    "INT: MASTER SECRET[%d]: %s\n", GNUTLS_MASTER_SIZE,

    _gnutls_bin2hex(session->security_parameters.master_secret,

        GNUTLS_MASTER_SIZE, buf, sizeof(buf), NULL));

  return ret;

}

/* This is called when we want to receive the key exchange message of the

 * server. It does nothing if this type of message is not required

 * by the selected ciphersuite. 

 */

int _gnutls_send_server_kx_message(gnutls_session_t session, int again)

{

  gnutls_buffer_st buf;

  int ret = 0;

  mbuffer_st *bufel = NULL;

  if (session->internals.auth_struct->gnutls_generate_server_kx == NULL)

    return 0;

  if (again == 0) {

    ret = _gnutls_buffer_init_handshake_mbuffer(&buf);

    if (ret < 0)

      return gnutls_assert_val(ret);

    ret = session->internals.auth_struct->gnutls_generate_server_kx(

      session, &buf);

    if (ret == GNUTLS_E_INT_RET_0) {

      gnutls_assert();

      ret = 0;

      goto cleanup;

    }

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    bufel = _gnutls_buffer_to_mbuffer(&buf);

  }

  return _gnutls_send_handshake(session, bufel,

              GNUTLS_HANDSHAKE_SERVER_KEY_EXCHANGE);

cleanup:

  _gnutls_buffer_clear(&buf);

  return ret;

}

/* This function sends a certificate request message to the

 * client.

 */

int _gnutls_send_server_crt_request(gnutls_session_t session, int again)

{

  gnutls_buffer_st buf;

  int ret = 0;

  mbuffer_st *bufel = NULL;

  if (session->internals.auth_struct->gnutls_generate_server_crt_request ==

      NULL)

    return 0;

  if (session->internals.send_cert_req <= 0)

    return 0;

  if (again == 0) {

    ret = _gnutls_buffer_init_handshake_mbuffer(&buf);

    if (ret < 0)

      return gnutls_assert_val(ret);

    ret = session->internals.auth_struct

            ->gnutls_generate_server_crt_request(session,

                   &buf);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    bufel = _gnutls_buffer_to_mbuffer(&buf);

  }

  return _gnutls_send_handshake(session, bufel,

              GNUTLS_HANDSHAKE_CERTIFICATE_REQUEST);

cleanup:

  _gnutls_buffer_clear(&buf);

  return ret;

}

/* This is the function for the client to send the key

 * exchange message 

 */

int _gnutls_send_client_kx_message(gnutls_session_t session, int again)

{

  gnutls_buffer_st buf;

  int ret = 0;

  mbuffer_st *bufel = NULL;

  if (session->internals.auth_struct->gnutls_generate_client_kx == NULL)

    return 0;

  if (again == 0) {

    ret = _gnutls_buffer_init_handshake_mbuffer(&buf);

    if (ret < 0)

      return gnutls_assert_val(ret);

    ret = session->internals.auth_struct->gnutls_generate_client_kx(

      session, &buf);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    bufel = _gnutls_buffer_to_mbuffer(&buf);

  }

  return _gnutls_send_handshake(session, bufel,

              GNUTLS_HANDSHAKE_CLIENT_KEY_EXCHANGE);

cleanup:

  _gnutls_buffer_clear(&buf);

  return ret;

}

/* This is the function for the client to send the certificate

 * verify message

 */

int _gnutls_send_client_certificate_verify(gnutls_session_t session, int again)

{

  gnutls_buffer_st buf;

  int ret = 0;

  mbuffer_st *bufel = NULL;

  /* This is a packet that is only sent by the client

   */

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

    return 0;

  /* if certificate verify is not needed just exit 

   */

  if (!(session->internals.hsk_flags & HSK_CRT_ASKED))

    return 0;

  if (session->internals.auth_struct->gnutls_generate_client_crt_vrfy ==

      NULL) {

    gnutls_assert();

    return 0; /* this algorithm does not support cli_crt_vrfy 

         */

  }

  if (again == 0) {

    ret = _gnutls_buffer_init_handshake_mbuffer(&buf);

    if (ret < 0)

      return gnutls_assert_val(ret);

    ret = session->internals.auth_struct

            ->gnutls_generate_client_crt_vrfy(session, &buf);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    if (ret == 0)

      goto cleanup;

    bufel = _gnutls_buffer_to_mbuffer(&buf);

  }

  return _gnutls_send_handshake(session, bufel,

              GNUTLS_HANDSHAKE_CERTIFICATE_VERIFY);

cleanup:

  _gnutls_buffer_clear(&buf);

  return ret;

}

/* This is called when we want send our certificate

 */

int _gnutls_send_client_certificate(gnutls_session_t session, int again)

{

  gnutls_buffer_st buf;

  int ret = 0;

  mbuffer_st *bufel = NULL;

  if (!(session->internals.hsk_flags & HSK_CRT_ASKED))

    return 0;

  if (session->internals.auth_struct->gnutls_generate_client_certificate ==

      NULL)

    return 0;

  if (again == 0) {

    ret = _gnutls_buffer_init_handshake_mbuffer(&buf);

    if (ret < 0)

      return gnutls_assert_val(ret);

#ifdef ENABLE_SSL3

    if (get_num_version(session) != GNUTLS_SSL3 ||

        session->internals.selected_cert_list_length > 0)

#endif

    {

      /* TLS 1.x or SSL 3.0 with a valid certificate 

       */

      ret = session->internals.auth_struct

              ->gnutls_generate_client_certificate(

                session, &buf);

      if (ret < 0) {

        gnutls_assert();

        goto cleanup;

      }

    }

    bufel = _gnutls_buffer_to_mbuffer(&buf);

  }

#ifdef ENABLE_SSL3

  /* In the SSL 3.0 protocol we need to send a

   * no certificate alert instead of an

   * empty certificate.

   */

  if (get_num_version(session) == GNUTLS_SSL3 &&

      session->internals.selected_cert_list_length == 0) {

    _mbuffer_xfree(&bufel);

    return gnutls_alert_send(session, GNUTLS_AL_WARNING,

           GNUTLS_A_SSL3_NO_CERTIFICATE);

  } else /* TLS 1.0 or SSL 3.0 with a valid certificate 

         */

#endif

    return _gnutls_send_handshake(session, bufel,

                GNUTLS_HANDSHAKE_CERTIFICATE_PKT);

cleanup:

  _gnutls_buffer_clear(&buf);

  return ret;

}

/* This is called when we want send our certificate

 */

int _gnutls_send_server_certificate(gnutls_session_t session, int again)

{

  gnutls_buffer_st buf;

  int ret = 0;

  mbuffer_st *bufel = NULL;

  if (session->internals.auth_struct->gnutls_generate_server_certificate ==

      NULL)

    return 0;

  if (again == 0) {

    ret = _gnutls_buffer_init_handshake_mbuffer(&buf);

    if (ret < 0)

      return gnutls_assert_val(ret);

    ret = session->internals.auth_struct

            ->gnutls_generate_server_certificate(session,

                   &buf);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    bufel = _gnutls_buffer_to_mbuffer(&buf);

  }

  return _gnutls_send_handshake(session, bufel,

              GNUTLS_HANDSHAKE_CERTIFICATE_PKT);

cleanup:

  _gnutls_buffer_clear(&buf);

  return ret;

}

int _gnutls_recv_server_kx_message(gnutls_session_t session)

{

  gnutls_buffer_st buf;

  int ret = 0;

  unsigned int optflag = 0;

  if (session->internals.auth_struct->gnutls_process_server_kx != NULL) {

    /* Server key exchange packet is optional for PSK. */

    if (_gnutls_session_is_psk(session))

      optflag = 1;

    ret = _gnutls_recv_handshake(

      session, GNUTLS_HANDSHAKE_SERVER_KEY_EXCHANGE, optflag,

      &buf);

    if (ret < 0) {

      gnutls_assert();

      return ret;

    }

    ret = session->internals.auth_struct->gnutls_process_server_kx(

      session, buf.data, buf.length);

    _gnutls_buffer_clear(&buf);

    if (ret < 0) {

      gnutls_assert();

      return ret;

    }

  }

  return ret;

}

int _gnutls_recv_server_crt_request(gnutls_session_t session)

{

  gnutls_buffer_st buf;

  int ret = 0;

  if (session->internals.auth_struct->gnutls_process_server_crt_request !=

      NULL) {

    ret = _gnutls_recv_handshake(

      session, GNUTLS_HANDSHAKE_CERTIFICATE_REQUEST, 1, &buf);

    if (ret < 0)

      return ret;

    if (ret == 0 && buf.length == 0) {

      _gnutls_buffer_clear(&buf);

      return 0; /* ignored */

    }

    ret = session->internals.auth_struct

            ->gnutls_process_server_crt_request(

              session, buf.data, buf.length);

    _gnutls_buffer_clear(&buf);

    if (ret < 0)

      return ret;

  }

  return ret;

}

int _gnutls_recv_client_kx_message(gnutls_session_t session)

{

  gnutls_buffer_st buf;

  int ret = 0;

  /* Do key exchange only if the algorithm permits it */

  if (session->internals.auth_struct->gnutls_process_client_kx != NULL) {

    ret = _gnutls_recv_handshake(

      session, GNUTLS_HANDSHAKE_CLIENT_KEY_EXCHANGE, 0, &buf);

    if (ret < 0)

      return ret;

    ret = session->internals.auth_struct->gnutls_process_client_kx(

      session, buf.data, buf.length);

    _gnutls_buffer_clear(&buf);

    if (ret < 0)

      return ret;

  }

  return ret;

}

int _gnutls_recv_client_certificate(gnutls_session_t session)

{

  gnutls_buffer_st buf;

  int ret = 0;

  int optional;

  if (session->internals.auth_struct->gnutls_process_client_certificate ==

      NULL)

    return 0;

  /* if we have not requested a certificate then just return

   */

  if (session->internals.send_cert_req == 0) {

    return 0;

  }

  if (session->internals.send_cert_req == GNUTLS_CERT_REQUIRE)

    optional = 0;

  else

    optional = 1;

  ret = _gnutls_recv_handshake(session, GNUTLS_HANDSHAKE_CERTIFICATE_PKT,

             optional, &buf);

  if (ret < 0) {

    /* Handle the case of old SSL3 clients who send

     * a warning alert instead of an empty certificate to indicate

     * no certificate.

     */

#ifdef ENABLE_SSL3

    if (optional != 0 && ret == GNUTLS_E_WARNING_ALERT_RECEIVED &&

        get_num_version(session) == GNUTLS_SSL3 &&

        gnutls_alert_get(session) == GNUTLS_A_SSL3_NO_CERTIFICATE) {

      /* SSL3 does not send an empty certificate,

       * but this alert. So we just ignore it.

       */

      gnutls_assert();

      return 0;

    }

#endif

    /* certificate was required 

     */

    if ((ret == GNUTLS_E_WARNING_ALERT_RECEIVED ||

         ret == GNUTLS_E_FATAL_ALERT_RECEIVED) &&

        optional == 0) {

      gnutls_assert();

      return GNUTLS_E_NO_CERTIFICATE_FOUND;

    }

    return ret;

  }

  if (ret == 0 && buf.length == 0 && optional != 0) {

    /* Client has not sent the certificate message.

     * well I'm not sure we should accept this

     * behaviour.

     */

    gnutls_assert();

    ret = 0;

    goto cleanup;

  }

  ret = session->internals.auth_struct->gnutls_process_client_certificate(

    session, buf.data, buf.length);

  if (ret < 0 && ret != GNUTLS_E_NO_CERTIFICATE_FOUND) {

    gnutls_assert();

    goto cleanup;

  }

  /* ok we should expect a certificate verify message now 

   */

  if (ret == GNUTLS_E_NO_CERTIFICATE_FOUND && optional != 0)

    ret = 0;

  else

    session->internals.hsk_flags |= HSK_CRT_VRFY_EXPECTED;

cleanup:

  _gnutls_buffer_clear(&buf);

  return ret;

}

int _gnutls_recv_server_certificate(gnutls_session_t session)

{

  gnutls_buffer_st buf;

  int ret = 0;

  if (session->internals.auth_struct->gnutls_process_server_certificate !=

      NULL) {

    ret = _gnutls_recv_handshake(

      session, GNUTLS_HANDSHAKE_CERTIFICATE_PKT, 0, &buf);

    if (ret < 0) {

      gnutls_assert();

      return ret;

    }

    ret = session->internals.auth_struct

            ->gnutls_process_server_certificate(

              session, buf.data, buf.length);

    _gnutls_buffer_clear(&buf);

    if (ret < 0) {

      gnutls_assert();

      return ret;

    }

  }

  return ret;

}

/* Recv the client certificate verify. This packet may not

 * arrive if the peer did not send us a certificate.

 */

int _gnutls_recv_client_certificate_verify_message(gnutls_session_t session)

{

  gnutls_buffer_st buf;

  int ret = 0;

  if (session->internals.auth_struct->gnutls_process_client_crt_vrfy ==

      NULL)

    return 0;

  if (session->internals.send_cert_req == 0 ||

      (!(session->internals.hsk_flags & HSK_CRT_VRFY_EXPECTED))) {

    return 0;

  }

  ret = _gnutls_recv_handshake(

    session, GNUTLS_HANDSHAKE_CERTIFICATE_VERIFY, 1, &buf);

  if (ret < 0)

    return ret;

  if (ret == 0 && buf.length == 0 &&

      session->internals.send_cert_req == GNUTLS_CERT_REQUIRE) {

    /* certificate was required */

    gnutls_assert();

    ret = GNUTLS_E_NO_CERTIFICATE_FOUND;

    goto cleanup;

  }

  ret = session->internals.auth_struct->gnutls_process_client_crt_vrfy(

    session, buf.data, buf.length);

cleanup:

  _gnutls_buffer_clear(&buf);

  return ret;

}