/*

 * Copyright (C) 2011-2012 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/>

 *

 */

#include "gnutls_int.h"

#include "algorithms.h"

#include "errors.h"

#include "x509/common.h"

#include "state.h"

#include "c-strcase.h"

extern mod_auth_st rsa_auth_struct;

extern mod_auth_st dhe_rsa_auth_struct;

extern mod_auth_st ecdhe_rsa_auth_struct;

extern mod_auth_st ecdhe_psk_auth_struct;

extern mod_auth_st ecdhe_ecdsa_auth_struct;

extern mod_auth_st dhe_dss_auth_struct;

extern mod_auth_st anon_auth_struct;

extern mod_auth_st anon_ecdh_auth_struct;

extern mod_auth_st srp_auth_struct;

extern mod_auth_st psk_auth_struct;

extern mod_auth_st dhe_psk_auth_struct;

extern mod_auth_st rsa_psk_auth_struct;

extern mod_auth_st srp_rsa_auth_struct;

extern mod_auth_st srp_dss_auth_struct;

extern mod_auth_st vko_gost_auth_struct;

/* Cred type mappings to KX algorithms

 * The mappings are not 1-1. Some KX such as SRP_RSA require

 * more than one credentials type.

 */

typedef struct {

  gnutls_kx_algorithm_t algorithm;

  gnutls_credentials_type_t client_type;

  gnutls_credentials_type_t server_type; /* The type of credentials a server

             * needs to set */

} gnutls_cred_map;

static const gnutls_cred_map cred_mappings[] = {

  { GNUTLS_KX_ECDHE_RSA, GNUTLS_CRD_CERTIFICATE, GNUTLS_CRD_CERTIFICATE },

  { GNUTLS_KX_ECDHE_ECDSA, GNUTLS_CRD_CERTIFICATE,

    GNUTLS_CRD_CERTIFICATE },

  { GNUTLS_KX_RSA, GNUTLS_CRD_CERTIFICATE, GNUTLS_CRD_CERTIFICATE },

  { GNUTLS_KX_DHE_DSS, GNUTLS_CRD_CERTIFICATE, GNUTLS_CRD_CERTIFICATE },

  { GNUTLS_KX_DHE_RSA, GNUTLS_CRD_CERTIFICATE, GNUTLS_CRD_CERTIFICATE },

  { GNUTLS_KX_ECDHE_PSK, GNUTLS_CRD_PSK, GNUTLS_CRD_PSK },

  { GNUTLS_KX_PSK, GNUTLS_CRD_PSK, GNUTLS_CRD_PSK },

  { GNUTLS_KX_DHE_PSK, GNUTLS_CRD_PSK, GNUTLS_CRD_PSK },

  { GNUTLS_KX_RSA_PSK, GNUTLS_CRD_PSK, GNUTLS_CRD_CERTIFICATE },

  { GNUTLS_KX_SRP, GNUTLS_CRD_SRP, GNUTLS_CRD_SRP },

  { GNUTLS_KX_SRP_RSA, GNUTLS_CRD_SRP, GNUTLS_CRD_CERTIFICATE },

  { GNUTLS_KX_SRP_DSS, GNUTLS_CRD_SRP, GNUTLS_CRD_CERTIFICATE },

  { GNUTLS_KX_ANON_DH, GNUTLS_CRD_ANON, GNUTLS_CRD_ANON },

  { GNUTLS_KX_ANON_ECDH, GNUTLS_CRD_ANON, GNUTLS_CRD_ANON },

  { GNUTLS_KX_VKO_GOST_12, GNUTLS_CRD_CERTIFICATE,

    GNUTLS_CRD_CERTIFICATE },

  { 0, 0, 0 }

};

#define GNUTLS_KX_MAP_LOOP(b)                             \

  const gnutls_cred_map *p;                         \

  for (p = cred_mappings; p->algorithm != 0; p++) { \

    b;                                        \

  }

struct gnutls_kx_algo_entry {

  const char *name;

  gnutls_kx_algorithm_t algorithm;

  mod_auth_st *auth_struct;

  bool needs_dh_params;

  bool false_start;

};

typedef struct gnutls_kx_algo_entry gnutls_kx_algo_entry;

static const gnutls_kx_algo_entry _gnutls_kx_algorithms[] = {

#ifdef ENABLE_ECDHE

  { "ECDHE-RSA", GNUTLS_KX_ECDHE_RSA, &ecdhe_rsa_auth_struct, 0, 1 },

  { "ECDHE-ECDSA", GNUTLS_KX_ECDHE_ECDSA, &ecdhe_ecdsa_auth_struct, 0,

    1 },

#endif

  { "RSA", GNUTLS_KX_RSA, &rsa_auth_struct, 0, 0 },

#ifdef ENABLE_DHE

  { "DHE-RSA", GNUTLS_KX_DHE_RSA, &dhe_rsa_auth_struct, 1, 1 },

  { "DHE-DSS", GNUTLS_KX_DHE_DSS, &dhe_dss_auth_struct, 1, 1 },

#endif

#ifdef ENABLE_PSK

  { "PSK", GNUTLS_KX_PSK, &psk_auth_struct, 0, 0 },

  { "RSA-PSK", GNUTLS_KX_RSA_PSK, &rsa_psk_auth_struct, 0, 0 },

#ifdef ENABLE_DHE

  { "DHE-PSK", GNUTLS_KX_DHE_PSK, &dhe_psk_auth_struct,

    1 /* needs DHE params */, 0 },

#endif

#ifdef ENABLE_ECDHE

  { "ECDHE-PSK", GNUTLS_KX_ECDHE_PSK, &ecdhe_psk_auth_struct, 0, 0 },

#endif

#endif

#ifdef ENABLE_SRP

  { "SRP-DSS", GNUTLS_KX_SRP_DSS, &srp_dss_auth_struct, 0, 0 },

  { "SRP-RSA", GNUTLS_KX_SRP_RSA, &srp_rsa_auth_struct, 0, 0 },

  { "SRP", GNUTLS_KX_SRP, &srp_auth_struct, 0, 0 },

#endif

#if defined(ENABLE_ANON) && defined(ENABLE_DHE)

  { "ANON-DH", GNUTLS_KX_ANON_DH, &anon_auth_struct, 1, 0 },

#endif

#if defined(ENABLE_ANON) && defined(ENABLE_ECDHE)

  { "ANON-ECDH", GNUTLS_KX_ANON_ECDH, &anon_ecdh_auth_struct, 0, 0 },

#endif

#ifdef ENABLE_GOST

  { "VKO-GOST-12", GNUTLS_KX_VKO_GOST_12, &vko_gost_auth_struct, 0, 0 },

#endif

  /* for deprecated and legacy algorithms no longer supported, use

   * GNUTLS_KX_INVALID as an entry. This will make them available

   * as priority strings, but they will be a no-op.

   */

  { "RSA-EXPORT", GNUTLS_KX_INVALID, NULL, 0, 0 },

  { 0, 0, 0, 0, 0 }

};

#define GNUTLS_KX_LOOP(b)                                       \

  const gnutls_kx_algo_entry *p;                          \

  for (p = _gnutls_kx_algorithms; p->name != NULL; p++) { \

    b;                                              \

  }

#define GNUTLS_KX_ALG_LOOP(a)                           \

  GNUTLS_KX_LOOP(if (p->algorithm == algorithm) { \

    a;                                      \

    break;                                  \

  })

/* Key EXCHANGE functions */

mod_auth_st *_gnutls_kx_auth_struct(gnutls_kx_algorithm_t algorithm)

{

  mod_auth_st *ret = NULL;

  GNUTLS_KX_ALG_LOOP(ret = p->auth_struct);

  return ret;

}

/**

 * gnutls_kx_get_name:

 * @algorithm: is a key exchange algorithm

 *

 * Convert a #gnutls_kx_algorithm_t value to a string.

 *

 * Returns: a pointer to a string that contains the name of the

 *   specified key exchange algorithm, or %NULL.

 **/

const char *gnutls_kx_get_name(gnutls_kx_algorithm_t algorithm)

{

  const char *ret = NULL;

  /* avoid prefix */

  GNUTLS_KX_ALG_LOOP(ret = p->name);

  return ret;

}

/**

 * gnutls_kx_get_id:

 * @name: is a KX name

 *

 * Convert a string to a #gnutls_kx_algorithm_t value.  The names are

 * compared in a case insensitive way.

 *

 * Returns: an id of the specified KX algorithm, or %GNUTLS_KX_UNKNOWN

 *   on error.

 **/

gnutls_kx_algorithm_t gnutls_kx_get_id(const char *name)

{

  gnutls_kx_algorithm_t ret = GNUTLS_KX_UNKNOWN;

  GNUTLS_KX_LOOP(if (c_strcasecmp(p->name, name) == 0 &&

         (int)p->algorithm != GNUTLS_KX_INVALID) {

    ret = p->algorithm;

    break;

  });

  return ret;

}

/* As with gnutls_kx_get_id(), but it returns all known

 * key exchange algorithms (even legacy), with GNUTLS_KX_INVALID

 * value.

 */

int _gnutls_kx_get_id(const char *name)

{

  gnutls_kx_algorithm_t ret = GNUTLS_KX_UNKNOWN;

  GNUTLS_KX_LOOP(if (c_strcasecmp(p->name, name) == 0) {

    ret = p->algorithm;

    break;

  });

  return ret;

}

/**

 * gnutls_kx_list:

 *

 * Get a list of supported key exchange algorithms.

 *

 * This function is not thread safe.

 *

 * Returns: a (0)-terminated list of #gnutls_kx_algorithm_t integers

 * indicating the available key exchange algorithms.

 **/

const gnutls_kx_algorithm_t *gnutls_kx_list(void)

{

  static gnutls_kx_algorithm_t supported_kxs[MAX_ALGOS] = { 0 };

  if (supported_kxs[0] == 0) {

    int i = 0;

    GNUTLS_KX_LOOP(supported_kxs[i++] = p->algorithm);

    supported_kxs[i++] = 0;

  }

  return supported_kxs;

}

int _gnutls_kx_is_ok(gnutls_kx_algorithm_t algorithm)

{

  ssize_t ret = -1;

  GNUTLS_KX_ALG_LOOP(ret = p->algorithm);

  if (ret >= 0)

    ret = 0;

  else

    ret = 1;

  return ret;

}

bool _gnutls_kx_allows_false_start(gnutls_session_t session)

{

  unsigned algorithm = session->security_parameters.cs->kx_algorithm;

  bool needs_dh = 0;

  int bits;

  ssize_t ret = 0;

  GNUTLS_KX_ALG_LOOP(ret = p->false_start; needs_dh = p->needs_dh_params);

  if (ret != 0) {

    const gnutls_group_entry_st *e;

    e = get_group(session);

#if defined(ENABLE_DHE) || defined(ENABLE_ANON)

    if (needs_dh != 0) {

      bits = gnutls_sec_param_to_pk_bits(

        GNUTLS_PK_DH, GNUTLS_SEC_PARAM_HIGH);

      /* check whether sizes are sufficient */

      if (e && e->prime) {

        if (e->prime->size * 8 < (unsigned)bits)

          ret = 0;

      } else if (gnutls_dh_get_prime_bits(session) < bits)

        ret = 0;

    } else

#endif

      if (algorithm == GNUTLS_KX_ECDHE_RSA ||

          algorithm == GNUTLS_KX_ECDHE_ECDSA) {

      bits = gnutls_sec_param_to_pk_bits(

        GNUTLS_PK_EC, GNUTLS_SEC_PARAM_HIGH);

      if (e != NULL &&

          gnutls_ecc_curve_get_size(e->curve) * 8 < bits)

        ret = 0;

    }

  }

  return ret;

}

bool _gnutls_kx_needs_dh_params(gnutls_kx_algorithm_t algorithm)

{

  ssize_t ret = 0;

  GNUTLS_KX_ALG_LOOP(ret = p->needs_dh_params);

  return ret;

}

/* Returns the credentials type required for this

 * Key exchange method.

 */

gnutls_credentials_type_t

_gnutls_map_kx_get_cred(gnutls_kx_algorithm_t algorithm, int server)

{

  gnutls_credentials_type_t ret = -1;

  if (server) {

    GNUTLS_KX_MAP_LOOP(if (p->algorithm == algorithm) {

      ret = p->server_type;

      break;

    });

  } else {

    GNUTLS_KX_MAP_LOOP(if (p->algorithm == algorithm) {

      ret = p->client_type;

      break;

    });

  }

  return ret;

}