/src/gnutls/lib/state.c

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/*
 * Copyright (C) 2002-2016 Free Software Foundation, Inc.
 * Copyright (C) 2014-2016 Nikos Mavrogiannopoulos
 * Copyright (C) 2015-2018 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 to manipulate the session (gnutls_int.h), and some other stuff
 * are included here. The file's name is traditionally gnutls_state even if the
 * state has been renamed to session.
 */

#include "gnutls_int.h"
#include "errors.h"
#include "auth.h"
#include "num.h"
#include "datum.h"
#include "db.h"
#include "record.h"
#include "handshake.h"
#include "dh.h"
#include "buffers.h"
#include "mbuffers.h"
#include "state.h"
#include "constate.h"
#include "auth/cert.h"
#include "auth/anon.h"
#include "auth/psk.h"
#include "algorithms.h"
#include "hello_ext.h"
#include "system.h"
#include "random.h"
#include "fips.h"
#include <intprops.h>
#include <gnutls/dtls.h>
#include "dtls.h"
#include "tls13/session_ticket.h"
#include "ext/cert_types.h"
#include "locks.h"
#include "kx.h"

/* to be used by supplemental data support to disable TLS1.3
 * when supplemental data have been globally registered */
unsigned _gnutls_disable_tls13 = 0;

/* These should really be static, but src/tests.c calls them.  Make
   them public functions?  */
void _gnutls_rsa_pms_set_version(gnutls_session_t session, unsigned char major,
         unsigned char minor);

/**
 * gnutls_cipher_get:
 * @session: is a #gnutls_session_t type.
 *
 * Get the currently used cipher.
 *
 * Returns: the currently used cipher, a #gnutls_cipher_algorithm_t
 *   type.
 **/
gnutls_cipher_algorithm_t gnutls_cipher_get(gnutls_session_t session)
{
  record_parameters_st *record_params;
  int ret;

  ret = _gnutls_epoch_get(session, EPOCH_READ_CURRENT, &record_params);
  if (ret < 0)
    return gnutls_assert_val(GNUTLS_CIPHER_NULL);

  return record_params->cipher->id;
}

/**
 * gnutls_early_cipher_get:
 * @session: is a #gnutls_session_t type.
 *
 * Get the cipher algorithm used for encrypting early data.
 *
 * Returns: the cipher used for early data, a
 *   #gnutls_cipher_algorithm_t type.
 *
 * Since: 3.7.2
 **/
gnutls_cipher_algorithm_t gnutls_early_cipher_get(gnutls_session_t session)
{
  const cipher_entry_st *ce;

  if (!(session->internals.hsk_flags & HSK_EARLY_DATA_IN_FLIGHT)) {
    return gnutls_assert_val(GNUTLS_CIPHER_UNKNOWN);
  }

  if (unlikely(session->internals.resumed_security_parameters.cs ==
         NULL)) {
    return gnutls_assert_val(GNUTLS_CIPHER_UNKNOWN);
  }

  ce = cipher_to_entry(session->internals.resumed_security_parameters.cs
             ->block_algorithm);
  if (unlikely(ce == NULL)) {
    return gnutls_assert_val(GNUTLS_CIPHER_UNKNOWN);
  }

  return ce->id;
}

/**
 * gnutls_certificate_type_get:
 * @session: is a #gnutls_session_t type.
 *
 * This function returns the type of the certificate that is negotiated
 * for this side to send to the peer. The certificate type is by default
 * X.509, unless an alternative certificate type is enabled by
 * gnutls_init() and negotiated during the session.
 *
 * Resumed sessions will return the certificate type that was negotiated
 * and used in the original session.
 *
 * As of version 3.6.4 it is recommended to use
 * gnutls_certificate_type_get2() which is more fine-grained.
 *
 * Returns: the currently used #gnutls_certificate_type_t certificate
 *   type as negotiated for 'our' side of the connection.
 **/
gnutls_certificate_type_t gnutls_certificate_type_get(gnutls_session_t session)
{
  return gnutls_certificate_type_get2(session, GNUTLS_CTYPE_OURS);
}

/**
 * gnutls_certificate_type_get2:
 * @session: is a #gnutls_session_t type.
 * @target: is a #gnutls_ctype_target_t type.
 *
 * This function returns the type of the certificate that a side
 * is negotiated to use.  The certificate type is by default X.509,
 * unless an alternative certificate type is enabled by gnutls_init() and
 * negotiated during the session.
 *
 * The @target parameter specifies whether to request the negotiated
 * certificate type for the client (%GNUTLS_CTYPE_CLIENT),
 * or for the server (%GNUTLS_CTYPE_SERVER). Additionally, in P2P mode
 * connection set up where you don't know in advance who will be client
 * and who will be server you can use the flag (%GNUTLS_CTYPE_OURS) and
 * (%GNUTLS_CTYPE_PEERS) to retrieve the corresponding certificate types.
 *
 * Resumed sessions will return the certificate type that was negotiated
 * and used in the original session. That is, this function can be used
 * to reliably determine the type of the certificate returned by
 * gnutls_certificate_get_peers().
 *
 * Returns: the currently used #gnutls_certificate_type_t certificate
 *   type for the client or the server.
 *
 * Since: 3.6.4
 **/
gnutls_certificate_type_t
gnutls_certificate_type_get2(gnutls_session_t session,
           gnutls_ctype_target_t target)
{
  /* We want to inline this function so therefore
   * we've defined it in gnutls_int.h */
  return get_certificate_type(session, target);
}

/**
 * gnutls_kx_get:
 * @session: is a #gnutls_session_t type.
 *
 * Get the currently used key exchange algorithm.
 *
 * This function will return %GNUTLS_KX_ECDHE_RSA, or %GNUTLS_KX_DHE_RSA
 * under TLS 1.3, to indicate an elliptic curve DH key exchange or
 * a finite field one. The precise group used is available
 * by calling gnutls_group_get() instead.
 *
 * Returns: the key exchange algorithm used in the last handshake, a
 *   #gnutls_kx_algorithm_t value.
 **/
gnutls_kx_algorithm_t gnutls_kx_get(gnutls_session_t session)
{
  if (session->security_parameters.cs == 0)
    return 0;

  if (session->security_parameters.cs->kx_algorithm == 0) { /* TLS 1.3 */
    const version_entry_st *ver = get_version(session);
    const gnutls_group_entry_st *group = get_group(session);

    if (ver->tls13_sem) {
      if (session->internals.hsk_flags & HSK_PSK_SELECTED) {
        if (group) {
          if (group->pk == GNUTLS_PK_DH)
            return GNUTLS_KX_DHE_PSK;
          else
            return GNUTLS_KX_ECDHE_PSK;
        } else {
          return GNUTLS_KX_PSK;
        }
      } else if (group) {
        if (group->pk == GNUTLS_PK_DH)
          return GNUTLS_KX_DHE_RSA;
        else
          return GNUTLS_KX_ECDHE_RSA;
      }
    }
  }

  return session->security_parameters.cs->kx_algorithm;
}

/**
 * gnutls_mac_get:
 * @session: is a #gnutls_session_t type.
 *
 * Get the currently used MAC algorithm.
 *
 * Returns: the currently used mac algorithm, a
 *   #gnutls_mac_algorithm_t value.
 **/
gnutls_mac_algorithm_t gnutls_mac_get(gnutls_session_t session)
{
  record_parameters_st *record_params;
  int ret;

  ret = _gnutls_epoch_get(session, EPOCH_READ_CURRENT, &record_params);
  if (ret < 0)
    return gnutls_assert_val(GNUTLS_MAC_NULL);

  return record_params->mac->id;
}

/**
 * gnutls_compression_get:
 * @session: is a #gnutls_session_t type.
 *
 * Get the currently used compression algorithm.
 *
 * Returns: the currently used compression method, a
 *   #gnutls_compression_method_t value.
 **/
gnutls_compression_method_t gnutls_compression_get(gnutls_session_t session)
{
  return GNUTLS_COMP_NULL;
}

/**
 * gnutls_prf_hash_get:
 * @session: is a #gnutls_session_t type.
 *
 * Get the currently used hash algorithm. In TLS 1.3, the hash
 * algorithm is used for both the key derivation function and
 * handshake message authentication code. In TLS 1.2, it matches the
 * hash algorithm used for PRF.
 *
 * Returns: the currently used hash algorithm, a
 *    #gnutls_digest_algorithm_t value.
 *
 * Since: 3.6.13
 **/
gnutls_digest_algorithm_t gnutls_prf_hash_get(const gnutls_session_t session)
{
  if (session->security_parameters.prf == NULL)
    return gnutls_assert_val(GNUTLS_DIG_UNKNOWN);

  if (session->security_parameters.prf->id >= GNUTLS_MAC_AEAD)
    return gnutls_assert_val(GNUTLS_DIG_UNKNOWN);

  return (gnutls_digest_algorithm_t)session->security_parameters.prf->id;
}

/**
 * gnutls_early_prf_hash_get:
 * @session: is a #gnutls_session_t type.
 *
 * Get the hash algorithm used as a PRF to derive keys for encrypting
 * early data in TLS 1.3.
 *
 * Returns: the hash algorithm used for early data, a
 *    #gnutls_digest_algorithm_t value.
 *
 * Since: 3.7.2
 **/
gnutls_digest_algorithm_t
gnutls_early_prf_hash_get(const gnutls_session_t session)
{
  if (!(session->internals.hsk_flags & HSK_EARLY_DATA_IN_FLIGHT)) {
    return gnutls_assert_val(GNUTLS_DIG_UNKNOWN);
  }

  if (unlikely(session->internals.resumed_security_parameters.prf ==
         NULL)) {
    return gnutls_assert_val(GNUTLS_DIG_UNKNOWN);
  }

  if (unlikely(session->internals.resumed_security_parameters.prf->id >=
         GNUTLS_MAC_AEAD)) {
    return gnutls_assert_val(GNUTLS_DIG_UNKNOWN);
  }

  return (gnutls_digest_algorithm_t)
    session->internals.resumed_security_parameters.prf->id;
}

/**
 * gnutls_ciphersuite_get:
 * @session: is a #gnutls_session_t type.
 *
 * Get the canonical name of negotiated TLS ciphersuite.  The names
 * returned by this function match the IANA registry, with one
 * exception:
 *
 *   TLS_DHE_DSS_RC4_128_SHA { 0x00, 0x66 }
 *
 * which is reserved for compatibility.
 *
 * To get a detailed description of the current ciphersuite, it is
 * recommended to use gnutls_session_get_desc().
 *
 * Returns: a string that contains the canonical name of a TLS ciphersuite,
 *     or %NULL if the handshake is not completed.
 *
 * Since: 3.7.4
 **/
const char *gnutls_ciphersuite_get(gnutls_session_t session)
{
  if (unlikely(session->internals.handshake_in_progress)) {
    return NULL;
  }
  return session->security_parameters.cs->canonical_name;
}

void reset_binders(gnutls_session_t session)
{
  _gnutls_free_temp_key_datum(&session->key.binders[0].psk);
  _gnutls_free_temp_key_datum(&session->key.binders[1].psk);
  memset(session->key.binders, 0, sizeof(session->key.binders));
}

/* Check whether certificate credentials of type @cert_type are set
 * for the current session.
 */
static bool _gnutls_has_cert_credentials(gnutls_session_t session,
           gnutls_certificate_type_t cert_type)
{
  unsigned i;
  unsigned cert_found = 0;
  gnutls_certificate_credentials_t cred;

  /* First, check for certificate credentials. If we have no certificate
   * credentials set then we don't support certificates at all.
   */
  cred = (gnutls_certificate_credentials_t)_gnutls_get_cred(
    session, GNUTLS_CRD_CERTIFICATE);

  if (cred == NULL)
    return false;

  /* There are credentials initialized. Now check whether we can find
   * pre-set certificates of the required type, but only if we don't
   * use the callback functions.
   */
  if (cred->get_cert_callback3 == NULL) {
    for (i = 0; i < cred->ncerts; i++) {
      if (cred->certs[i].cert_list[0].type == cert_type) {
        cert_found = 1;
        break;
      }
    }

    if (cert_found == 0) {
      /* No matching certificate found. */
      return false;
    }
  }

  return true; // OK
}

/* Check if the given certificate type is supported.
 * This means that it is enabled by the priority functions,
 * and in some cases a matching certificate exists. A check for
 * the latter can be toggled via the parameter @check_credentials.
 */
bool _gnutls_session_is_cert_type_supported(gnutls_session_t session,
              gnutls_certificate_type_t cert_type,
              bool check_credentials,
              gnutls_ctype_target_t target)
{
  unsigned i;
  priority_st *ctype_priorities;

  // Check whether this cert type is enabled by the application
  if (!is_cert_type_enabled(session, cert_type))
    return gnutls_assert_val(GNUTLS_E_UNSUPPORTED_CERTIFICATE_TYPE);

  // Perform a credentials check if requested
  if (check_credentials) {
    if (!_gnutls_has_cert_credentials(session, cert_type))
      return gnutls_assert_val(
        GNUTLS_E_UNSUPPORTED_CERTIFICATE_TYPE);
  }

  /* So far so good. We have the required credentials (if needed).
   * Now check whether we are allowed to use them according to our
   * priorities.
   */
  // Which certificate type should we query?
  switch (target) {
  case GNUTLS_CTYPE_CLIENT:
    ctype_priorities =
      &(session->internals.priorities->client_ctype);
    break;
  case GNUTLS_CTYPE_SERVER:
    ctype_priorities =
      &(session->internals.priorities->server_ctype);
    break;
  default:
    return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
  }

  // No explicit priorities set, and default ctype is asked
  if (ctype_priorities->num_priorities == 0 &&
      cert_type == DEFAULT_CERT_TYPE)
    return 0;

  /* Now lets find out whether our cert type is in our priority
   * list, i.e. set of allowed cert types.
   */
  for (i = 0; i < ctype_priorities->num_priorities; i++) {
    if (ctype_priorities->priorities[i] == cert_type)
      return 0;
  }

  return GNUTLS_E_UNSUPPORTED_CERTIFICATE_TYPE;
}

static void deinit_keys(gnutls_session_t session)
{
  const version_entry_st *vers = get_version(session);

  if (vers == NULL)
    return;

  gnutls_pk_params_release(&session->key.kshare.ecdhx_params);
  gnutls_pk_params_release(&session->key.kshare.ecdh_params);
  gnutls_pk_params_release(&session->key.kshare.dh_params);
  gnutls_pk_params_release(&session->key.kshare.kem_params);

  if (!vers->tls13_sem && session->key.binders[0].prf == NULL) {
    gnutls_pk_params_release(&session->key.proto.tls12.ecdh.params);
    gnutls_pk_params_release(&session->key.proto.tls12.dh.params);
    zrelease_temp_mpi_key(&session->key.proto.tls12.ecdh.x);
    zrelease_temp_mpi_key(&session->key.proto.tls12.ecdh.y);
    _gnutls_free_temp_key_datum(&session->key.proto.tls12.ecdh.raw);

    zrelease_temp_mpi_key(&session->key.proto.tls12.dh.client_Y);

    /* SRP */
    zrelease_temp_mpi_key(&session->key.proto.tls12.srp.srp_p);
    zrelease_temp_mpi_key(&session->key.proto.tls12.srp.srp_g);
    zrelease_temp_mpi_key(&session->key.proto.tls12.srp.srp_key);

    zrelease_temp_mpi_key(&session->key.proto.tls12.srp.u);
    zrelease_temp_mpi_key(&session->key.proto.tls12.srp.a);
    zrelease_temp_mpi_key(&session->key.proto.tls12.srp.x);
    zrelease_temp_mpi_key(&session->key.proto.tls12.srp.A);
    zrelease_temp_mpi_key(&session->key.proto.tls12.srp.B);
    zrelease_temp_mpi_key(&session->key.proto.tls12.srp.b);
  } else {
    gnutls_memset(session->key.proto.tls13.temp_secret, 0,
            sizeof(session->key.proto.tls13.temp_secret));
  }

  reset_binders(session);
  _gnutls_free_temp_key_datum(&session->key.key);
}

/* An internal version of _gnutls_handshake_internal_state_clear(),
 * it will not attempt to deallocate, only initialize */
static void handshake_internal_state_clear1(gnutls_session_t session)
{
  /* by default no selected certificate */
  session->internals.adv_version_major = 0;
  session->internals.adv_version_minor = 0;
  session->internals.direction = 0;

  /* use out of band data for the last
   * handshake messages received.
   */
  session->internals.last_handshake_in = -1;
  session->internals.last_handshake_out = -1;

  session->internals.resumable = true;

  session->internals.handshake_suspicious_loops = 0;
  session->internals.dtls.hsk_read_seq = 0;
  session->internals.dtls.hsk_write_seq = 0;

  session->internals.cand_ec_group = 0;
  session->internals.cand_dh_group = 0;

  session->internals.hrr_cs[0] = CS_INVALID_MAJOR;
  session->internals.hrr_cs[1] = CS_INVALID_MINOR;

  session->internals.client_hello_exts_set = false;
}

/* This function will clear all the variables in internals
 * structure within the session, which depend on the current handshake.
 * This is used to allow further handshakes.
 */
void _gnutls_handshake_internal_state_clear(gnutls_session_t session)
{
  handshake_internal_state_clear1(session);

  _gnutls_handshake_hash_buffers_clear(session);
  deinit_keys(session);

  _gnutls_epoch_gc(session);

  session->internals.handshake_abs_timeout.tv_sec = 0;
  session->internals.handshake_abs_timeout.tv_nsec = 0;
  session->internals.handshake_in_progress = 0;

  session->internals.tfo.connect_addrlen = 0;
  session->internals.tfo.connect_only = 0;
  session->internals.early_data_received = 0;
  session->internals.session_ticket_renew = 0;
}

/**
 * gnutls_init:
 * @session: is a pointer to a #gnutls_session_t type.
 * @flags: indicate if this session is to be used for server or client.
 *
 * This function initializes the provided session. Every session must
 * be initialized before use, and after successful initialization and
 * use must be deinitialized by calling gnutls_deinit().
 *
 * @flags can be any combination of flags from %gnutls_init_flags_t.
 *
 * Note that since version 3.1.2 this function enables some common
 * TLS extensions such as session tickets and OCSP certificate status
 * request in client side by default. To prevent that use the %GNUTLS_NO_DEFAULT_EXTENSIONS
 * flag.
 *
 * Note that it is never mandatory to use gnutls_deinit() after this
 * function fails.  Since gnutls 3.8.0, it is safe to unconditionally
 * use gnutls_deinit() even after failure regardless of whether the
 * memory was initialized prior to gnutls_init(); however, clients
 * wanting to be portable to older versions of the library should
 * either skip deinitialization on failure, or pre-initialize the
 * memory passed in to gnutls_init() to all zeroes via memset() or
 * similar.
 *
 * Returns: %GNUTLS_E_SUCCESS on success, or an error code.
 **/
int gnutls_init(gnutls_session_t *session, unsigned int flags)
{
  int ret;

  *session = NULL;
  FAIL_IF_LIB_ERROR;

  *session = gnutls_calloc(1, sizeof(struct gnutls_session_int));
  if (*session == NULL)
    return GNUTLS_E_MEMORY_ERROR;

  ret = gnutls_mutex_init(&(*session)->internals.post_negotiation_lock);
  if (ret < 0) {
    gnutls_assert();
    gnutls_free(*session);
    return ret;
  }

  ret = gnutls_mutex_init(&(*session)->internals.epoch_lock);
  if (ret < 0) {
    gnutls_assert();
    gnutls_mutex_deinit(
      &(*session)->internals.post_negotiation_lock);
    gnutls_free(*session);
    return ret;
  }

  ret = _gnutls_epoch_setup_next(*session, 1, NULL);
  if (ret < 0) {
    gnutls_mutex_deinit(
      &(*session)->internals.post_negotiation_lock);
    gnutls_mutex_deinit(&(*session)->internals.epoch_lock);
    gnutls_free(*session);
    return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);
  }
  _gnutls_epoch_bump(*session);

  (*session)->security_parameters.entity =
    (flags & GNUTLS_SERVER ? GNUTLS_SERVER : GNUTLS_CLIENT);

  /* the default certificate type for TLS */
  (*session)->security_parameters.client_ctype = DEFAULT_CERT_TYPE;
  (*session)->security_parameters.server_ctype = DEFAULT_CERT_TYPE;

  /* Initialize buffers */
  _gnutls_buffer_init(&(*session)->internals.handshake_hash_buffer);
  _gnutls_buffer_init(&(*session)->internals.post_handshake_hash_buffer);
  _gnutls_buffer_init(&(*session)->internals.hb_remote_data);
  _gnutls_buffer_init(&(*session)->internals.hb_local_data);
  _gnutls_buffer_init(&(*session)->internals.record_presend_buffer);
  _gnutls_buffer_init(&(*session)->internals.record_key_update_buffer);
  _gnutls_buffer_init(&(*session)->internals.reauth_buffer);

  _mbuffer_head_init(&(*session)->internals.record_buffer);
  _mbuffer_head_init(&(*session)->internals.record_send_buffer);
  _mbuffer_head_init(&(*session)->internals.record_recv_buffer);
  _mbuffer_head_init(&(*session)->internals.early_data_recv_buffer);
  _gnutls_buffer_init(&(*session)->internals.early_data_presend_buffer);

  _mbuffer_head_init(&(*session)->internals.handshake_send_buffer);
  _gnutls_handshake_recv_buffer_init(*session);

  (*session)->internals.expire_time = DEFAULT_EXPIRE_TIME;

  /* Ticket key rotation - set the default X to 3 times the ticket expire time */
  (*session)->key.totp.last_result = 0;

  gnutls_handshake_set_max_packet_length((*session),
                 MAX_HANDSHAKE_PACKET_SIZE);

  /* set the socket pointers to -1;
   */
  (*session)->internals.transport_recv_ptr = (gnutls_transport_ptr_t)-1;
  (*session)->internals.transport_send_ptr = (gnutls_transport_ptr_t)-1;

  /* set the default maximum record size for TLS
   */
  (*session)->security_parameters.max_record_recv_size =
    DEFAULT_MAX_RECORD_SIZE;
  (*session)->security_parameters.max_record_send_size =
    DEFAULT_MAX_RECORD_SIZE;
  (*session)->security_parameters.max_user_record_recv_size =
    DEFAULT_MAX_RECORD_SIZE;
  (*session)->security_parameters.max_user_record_send_size =
    DEFAULT_MAX_RECORD_SIZE;

  /* set the default early data size for TLS
   */
  if ((*session)->security_parameters.entity == GNUTLS_SERVER) {
    (*session)->security_parameters.max_early_data_size =
      DEFAULT_MAX_EARLY_DATA_SIZE;
  } else {
    (*session)->security_parameters.max_early_data_size = 0;
  }

  /* Everything else not initialized here is initialized as NULL
   * or 0. This is why calloc is used. However, we want to
   * ensure that certain portions of data are initialized at
   * runtime before being used. Mark such regions with a
   * valgrind client request as undefined.
   */
  _gnutls_memory_mark_undefined(
    (*session)->security_parameters.master_secret,
    GNUTLS_MASTER_SIZE);
  _gnutls_memory_mark_undefined(
    (*session)->security_parameters.client_random,
    GNUTLS_RANDOM_SIZE);
  _gnutls_memory_mark_undefined(
    (*session)->security_parameters.server_random,
    GNUTLS_RANDOM_SIZE);
  _gnutls_memory_mark_undefined((*session)->key.session_ticket_key,
              TICKET_MASTER_KEY_SIZE);
  _gnutls_memory_mark_undefined((*session)->key.previous_ticket_key,
              TICKET_MASTER_KEY_SIZE);
  _gnutls_memory_mark_undefined((*session)->key.initial_stek,
              TICKET_MASTER_KEY_SIZE);

  handshake_internal_state_clear1(*session);

#ifdef MSG_NOSIGNAL
  if (flags & GNUTLS_NO_SIGNAL)
    gnutls_transport_set_vec_push_function(*session,
                   system_writev_nosignal);
  else
#endif
    gnutls_transport_set_vec_push_function(*session, system_writev);
  (*session)->internals.pull_timeout_func = gnutls_system_recv_timeout;
  (*session)->internals.pull_func = system_read;
  (*session)->internals.errno_func = system_errno;

  (*session)->internals.saved_username = NULL;
  (*session)->internals.saved_username_size = -1;

  /* heartbeat timeouts */
  (*session)->internals.hb_retrans_timeout_ms = 1000;
  (*session)->internals.hb_total_timeout_ms = 60000;

  if (flags & GNUTLS_DATAGRAM) {
    (*session)->internals.dtls.mtu = DTLS_DEFAULT_MTU;
    (*session)->internals.transport = GNUTLS_DGRAM;

    gnutls_dtls_set_timeouts(*session, DTLS_RETRANS_TIMEOUT, 60000);
  } else {
    (*session)->internals.transport = GNUTLS_STREAM;
  }

  /* Enable useful extensions */
  if ((flags & GNUTLS_CLIENT) &&
      !(flags & GNUTLS_NO_DEFAULT_EXTENSIONS)) {
#ifdef ENABLE_OCSP
    if (!(flags & GNUTLS_NO_STATUS_REQUEST))
      gnutls_ocsp_status_request_enable_client(*session, NULL,
                 0, NULL);
#endif
  }

  /* session tickets in server side are enabled by setting a key */
  if (flags & GNUTLS_SERVER)
    flags |= GNUTLS_NO_TICKETS;

  (*session)->internals.flags = flags;

  if (_gnutls_disable_tls13 != 0)
    (*session)->internals.flags |= INT_FLAG_NO_TLS13;

  /* Install the default keylog function */
  gnutls_session_set_keylog_function(*session, _gnutls_nss_keylog_func);

  return 0;
}

/**
 * gnutls_deinit:
 * @session: is a #gnutls_session_t type.
 *
 * This function clears all buffers associated with the @session.
 * This function will also remove session data from the session
 * database if the session was terminated abnormally.
 **/
void gnutls_deinit(gnutls_session_t session)
{
  unsigned int i;

  if (session == NULL)
    return;

  /* remove auth info firstly */
  _gnutls_free_auth_info(session);

  _gnutls_handshake_internal_state_clear(session);
  _gnutls_handshake_io_buffer_clear(session);
  _gnutls_hello_ext_priv_deinit(session);

  for (i = 0; i < MAX_EPOCH_INDEX; i++)
    if (session->record_parameters[i] != NULL) {
      _gnutls_epoch_free(session,
             session->record_parameters[i]);
      session->record_parameters[i] = NULL;
    }

  _gnutls_buffer_clear(&session->internals.handshake_hash_buffer);
  _gnutls_buffer_clear(&session->internals.post_handshake_hash_buffer);
  _gnutls_buffer_clear(&session->internals.hb_remote_data);
  _gnutls_buffer_clear(&session->internals.hb_local_data);
  _gnutls_buffer_clear(&session->internals.record_presend_buffer);
  _gnutls_buffer_clear(&session->internals.record_key_update_buffer);
  _gnutls_buffer_clear(&session->internals.reauth_buffer);

  _mbuffer_head_clear(&session->internals.record_buffer);
  _mbuffer_head_clear(&session->internals.record_recv_buffer);
  _mbuffer_head_clear(&session->internals.record_send_buffer);

  _mbuffer_head_clear(&session->internals.early_data_recv_buffer);
  _gnutls_buffer_clear(&session->internals.early_data_presend_buffer);

  _gnutls_free_datum(&session->internals.resumption_data);
  _gnutls_free_datum(&session->internals.dtls.dcookie);

  for (i = 0; i < session->internals.rexts_size; i++)
    gnutls_free(session->internals.rexts[i].name);
  gnutls_free(session->internals.rexts);
  gnutls_free(session->internals.post_handshake_cr_context.data);

  gnutls_free(session->internals.saved_username);
  gnutls_free(session->internals.rsup);

  gnutls_credentials_clear(session);
  _gnutls_selected_certs_deinit(session);

  /* destroy any session ticket we may have received */
  tls13_ticket_deinit(&session->internals.tls13_ticket);

  /* we rely on priorities' internal reference counting */
  gnutls_priority_deinit(session->internals.priorities);

  /* overwrite any temp TLS1.3 keys */
  gnutls_memset(&session->key.proto, 0, sizeof(session->key.proto));

  /* clear session ticket keys */
  _gnutls_memory_mark_defined(session->key.session_ticket_key,
            TICKET_MASTER_KEY_SIZE);
  gnutls_memset(&session->key.session_ticket_key, 0,
          TICKET_MASTER_KEY_SIZE);
  _gnutls_memory_mark_undefined(session->key.session_ticket_key,
              TICKET_MASTER_KEY_SIZE);

  _gnutls_memory_mark_defined(session->key.previous_ticket_key,
            TICKET_MASTER_KEY_SIZE);
  gnutls_memset(&session->key.previous_ticket_key, 0,
          TICKET_MASTER_KEY_SIZE);
  _gnutls_memory_mark_undefined(session->key.previous_ticket_key,
              TICKET_MASTER_KEY_SIZE);

  _gnutls_memory_mark_defined(session->key.initial_stek,
            TICKET_MASTER_KEY_SIZE);
  gnutls_memset(&session->key.initial_stek, 0, TICKET_MASTER_KEY_SIZE);
  _gnutls_memory_mark_undefined(session->key.initial_stek,
              TICKET_MASTER_KEY_SIZE);

  gnutls_mutex_deinit(&session->internals.post_negotiation_lock);
  gnutls_mutex_deinit(&session->internals.epoch_lock);

  gnutls_free(session);
}

int _gnutls_dh_set_peer_public(gnutls_session_t session, bigint_t public)
{
  dh_info_st *dh;
  int ret;

  switch (gnutls_auth_get_type(session)) {
  case GNUTLS_CRD_ANON: {
    anon_auth_info_t info;
    info = _gnutls_get_auth_info(session, GNUTLS_CRD_ANON);
    if (info == NULL)
      return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

    dh = &info->dh;
    break;
  }
  case GNUTLS_CRD_PSK: {
    psk_auth_info_t info;
    info = _gnutls_get_auth_info(session, GNUTLS_CRD_PSK);
    if (info == NULL)
      return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

    dh = &info->dh;
    break;
  }
  case GNUTLS_CRD_CERTIFICATE: {
    cert_auth_info_t info;

    info = _gnutls_get_auth_info(session, GNUTLS_CRD_CERTIFICATE);
    if (info == NULL)
      return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

    dh = &info->dh;
    break;
  }
  default:
    return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);
  }

  if (dh->public_key.data)
    _gnutls_free_datum(&dh->public_key);

  ret = _gnutls_mpi_dprint_lz(public, &dh->public_key);
  if (ret < 0) {
    gnutls_assert();
    return ret;
  }

  return 0;
}

int _gnutls_dh_set_secret_bits(gnutls_session_t session, unsigned bits)
{
  switch (gnutls_auth_get_type(session)) {
  case GNUTLS_CRD_ANON: {
    anon_auth_info_t info;
    info = _gnutls_get_auth_info(session, GNUTLS_CRD_ANON);
    if (info == NULL)
      return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);
    info->dh.secret_bits = bits;
    break;
  }
  case GNUTLS_CRD_PSK: {
    psk_auth_info_t info;
    info = _gnutls_get_auth_info(session, GNUTLS_CRD_PSK);
    if (info == NULL)
      return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);
    info->dh.secret_bits = bits;
    break;
  }
  case GNUTLS_CRD_CERTIFICATE: {
    cert_auth_info_t info;

    info = _gnutls_get_auth_info(session, GNUTLS_CRD_CERTIFICATE);
    if (info == NULL)
      return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

    info->dh.secret_bits = bits;
    break;
  default:
    return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);
  }
  }

  return 0;
}

/* Sets the prime and the generator in the auth info structure.
 */
int _gnutls_dh_save_group(gnutls_session_t session, bigint_t gen,
        bigint_t prime)
{
  dh_info_st *dh;
  int ret;

  switch (gnutls_auth_get_type(session)) {
  case GNUTLS_CRD_ANON: {
    anon_auth_info_t info;
    info = _gnutls_get_auth_info(session, GNUTLS_CRD_ANON);
    if (info == NULL)
      return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

    dh = &info->dh;
    break;
  }
  case GNUTLS_CRD_PSK: {
    psk_auth_info_t info;
    info = _gnutls_get_auth_info(session, GNUTLS_CRD_PSK);
    if (info == NULL)
      return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

    dh = &info->dh;
    break;
  }
  case GNUTLS_CRD_CERTIFICATE: {
    cert_auth_info_t info;

    info = _gnutls_get_auth_info(session, GNUTLS_CRD_CERTIFICATE);
    if (info == NULL)
      return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

    dh = &info->dh;
    break;
  }
  default:
    return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);
  }

  if (dh->prime.data)
    _gnutls_free_datum(&dh->prime);

  if (dh->generator.data)
    _gnutls_free_datum(&dh->generator);

  /* prime
   */
  ret = _gnutls_mpi_dprint_lz(prime, &dh->prime);
  if (ret < 0) {
    gnutls_assert();
    return ret;
  }

  /* generator
   */
  ret = _gnutls_mpi_dprint_lz(gen, &dh->generator);
  if (ret < 0) {
    gnutls_assert();
    _gnutls_free_datum(&dh->prime);
    return ret;
  }

  return 0;
}

/**
 * gnutls_certificate_send_x509_rdn_sequence:
 * @session: a #gnutls_session_t type.
 * @status: is 0 or 1
 *
 * If status is non zero, this function will order gnutls not to send
 * the rdnSequence in the certificate request message. That is the
 * server will not advertise its trusted CAs to the peer. If status
 * is zero then the default behaviour will take effect, which is to
 * advertise the server's trusted CAs.
 *
 * This function has no effect in clients, and in authentication
 * methods other than certificate with X.509 certificates.
 **/
void gnutls_certificate_send_x509_rdn_sequence(gnutls_session_t session,
                 int status)
{
  session->internals.ignore_rdn_sequence = status;
}

/*-
 * _gnutls_record_set_default_version - Used to set the default version for the first record packet
 * @session: is a #gnutls_session_t type.
 * @major: is a tls major version
 * @minor: is a tls minor version
 *
 * This function sets the default version that we will use in the first
 * record packet (client hello). This function is only useful to people
 * that know TLS internals and want to debug other implementations.
 -*/
void _gnutls_record_set_default_version(gnutls_session_t session,
          unsigned char major,
          unsigned char minor)
{
  session->internals.default_record_version[0] = major;
  session->internals.default_record_version[1] = minor;
}

/*-
 * _gnutls_hello_set_default_version - Used to set the default version for the first record packet
 * @session: is a #gnutls_session_t type.
 * @major: is a tls major version
 * @minor: is a tls minor version
 *
 * This function sets the default version that we will use in the first
 * record packet (client hello). This function is only useful to people
 * that know TLS internals and want to debug other implementations.
 -*/
void _gnutls_hello_set_default_version(gnutls_session_t session,
               unsigned char major, unsigned char minor)
{
  session->internals.default_hello_version[0] = major;
  session->internals.default_hello_version[1] = minor;
}

/**
 * gnutls_handshake_set_private_extensions:
 * @session: is a #gnutls_session_t type.
 * @allow: is an integer (0 or 1)
 *
 * This function will enable or disable the use of private cipher
 * suites (the ones that start with 0xFF).  By default or if @allow
 * is 0 then these cipher suites will not be advertised nor used.
 *
 * Currently GnuTLS does not include such cipher-suites or
 * compression algorithms.
 *
 * Enabling the private ciphersuites when talking to other than
 * gnutls servers and clients may cause interoperability problems.
 **/
void gnutls_handshake_set_private_extensions(gnutls_session_t session,
               int allow)
{
  /* we have no private extensions */
  return;
}

/**
 * gnutls_session_is_resumed:
 * @session: is a #gnutls_session_t type.
 *
 * Checks whether session is resumed or not. This is functional
 * for both server and client side.
 *
 * Returns: non zero if this session is resumed, or a zero if this is
 *   a new session.
 **/
int gnutls_session_is_resumed(gnutls_session_t session)
{
  if (session->security_parameters.entity == GNUTLS_CLIENT) {
    const version_entry_st *ver = get_version(session);
    if (ver && ver->tls13_sem) {
      return session->internals.resumed;
    }

    if (session->security_parameters.session_id_size > 0 &&
        session->security_parameters.session_id_size ==
          session->internals.resumed_security_parameters
            .session_id_size &&
        memcmp(session->security_parameters.session_id,
         session->internals.resumed_security_parameters
           .session_id,
         session->security_parameters.session_id_size) == 0)
      return 1;
  } else {
    if (session->internals.resumed)
      return 1;
  }

  return 0;
}

/**
 * gnutls_session_resumption_requested:
 * @session: is a #gnutls_session_t type.
 *
 * Check whether the client has asked for session resumption.
 * This function is valid only on server side.
 *
 * Returns: non zero if session resumption was asked, or a zero if not.
 **/
int gnutls_session_resumption_requested(gnutls_session_t session)
{
  if (session->security_parameters.entity == GNUTLS_CLIENT) {
    return 0;
  } else {
    return session->internals.resumption_requested;
  }
}

/*-
 * _gnutls_session_is_psk - Used to check whether this session uses PSK kx
 * @session: is a #gnutls_session_t type.
 *
 * This function will return non zero if this session uses a PSK key
 * exchange algorithm.
 -*/
int _gnutls_session_is_psk(gnutls_session_t session)
{
  gnutls_kx_algorithm_t kx;

  kx = session->security_parameters.cs->kx_algorithm;
  if (kx == GNUTLS_KX_PSK || kx == GNUTLS_KX_DHE_PSK ||
      kx == GNUTLS_KX_RSA_PSK)
    return 1;

  return 0;
}

/*-
 * _gnutls_session_is_ecc - Used to check whether this session uses ECC kx
 * @session: is a #gnutls_session_t type.
 *
 * This function will return non zero if this session uses an elliptic
 * curves key exchange exchange algorithm.
 -*/
int _gnutls_session_is_ecc(gnutls_session_t session)
{
  gnutls_kx_algorithm_t kx;

  /* We get the key exchange algorithm through the ciphersuite because
   * the negotiated key exchange might not have been set yet.
   */
  kx = session->security_parameters.cs->kx_algorithm;

  return _gnutls_kx_is_ecc(kx);
}

/**
 * gnutls_session_get_ptr:
 * @session: is a #gnutls_session_t type.
 *
 * Get user pointer for session.  Useful in callbacks.  This is the
 *   pointer set with gnutls_session_set_ptr().
 *
 * Returns: the user given pointer from the session structure, or
 *   %NULL if it was never set.
 **/
void *gnutls_session_get_ptr(gnutls_session_t session)
{
  return session->internals.user_ptr;
}

/**
 * gnutls_session_set_ptr:
 * @session: is a #gnutls_session_t type.
 * @ptr: is the user pointer
 *
 * This function will set (associate) the user given pointer @ptr to
 * the session structure.  This pointer can be accessed with
 * gnutls_session_get_ptr().
 **/
void gnutls_session_set_ptr(gnutls_session_t session, void *ptr)
{
  session->internals.user_ptr = ptr;
}

/**
 * gnutls_session_set_verify_function:
 * @session: is a #gnutls_session_t type.
 * @func: is the callback function
 *
 * This function sets a callback to be called when peer's certificate
 * has been received in order to verify it on receipt rather than
 * doing after the handshake is completed. This overrides any callback
 * set using gnutls_certificate_set_verify_function().
 *
 * The callback's function prototype is:
 * int (*callback)(gnutls_session_t);
 *
 * If the callback function is provided then gnutls will call it, in the
 * handshake, just after the certificate message has been received.
 * To verify or obtain the certificate the gnutls_certificate_verify_peers2(),
 * gnutls_certificate_type_get(), gnutls_certificate_get_peers() functions
 * can be used.
 *
 * The callback function should return 0 for the handshake to continue
 * or non-zero to terminate.
 *
 * Since: 3.4.6
 **/
void gnutls_session_set_verify_function(
  gnutls_session_t session, gnutls_certificate_verify_function *func)
{
  session->internals.verify_callback = func;
}

/**
 * gnutls_record_get_direction:
 * @session: is a #gnutls_session_t type.
 *
 * This function is useful to determine whether a GnuTLS function was interrupted
 * while sending or receiving, so that select() or poll() may be called appropriately.
 *
 * It provides information about the internals of the record
 * protocol and is only useful if a prior gnutls function call,
 * e.g.  gnutls_handshake(), was interrupted and returned
 * %GNUTLS_E_INTERRUPTED or %GNUTLS_E_AGAIN. After such an interrupt
 * applications may call select() or poll() before restoring the
 * interrupted GnuTLS function.
 *
 * This function's output is unreliable if you are using the same
 * @session in different threads for sending and receiving.
 *
 * Returns: 0 if interrupted while trying to read data, or 1 while trying to write data.
 **/
int gnutls_record_get_direction(gnutls_session_t session)
{
  return session->internals.direction;
}

/*-
 * _gnutls_rsa_pms_set_version - Sets a version to be used at the RSA PMS
 * @session: is a #gnutls_session_t type.
 * @major: is the major version to use
 * @minor: is the minor version to use
 *
 * This function will set the given version number to be used at the
 * RSA PMS secret. This is only useful to clients, which want to
 * test server's capabilities.
 -*/
void _gnutls_rsa_pms_set_version(gnutls_session_t session, unsigned char major,
         unsigned char minor)
{
  session->internals.rsa_pms_version[0] = major;
  session->internals.rsa_pms_version[1] = minor;
}

void _gnutls_session_client_cert_type_set(gnutls_session_t session,
            gnutls_certificate_type_t ct)
{
  _gnutls_handshake_log(
    "HSK[%p]: Selected client certificate type %s (%d)\n", session,
    gnutls_certificate_type_get_name(ct), ct);
  session->security_parameters.client_ctype = ct;
}

void _gnutls_session_server_cert_type_set(gnutls_session_t session,
            gnutls_certificate_type_t ct)
{
  _gnutls_handshake_log(
    "HSK[%p]: Selected server certificate type %s (%d)\n", session,
    gnutls_certificate_type_get_name(ct), ct);
  session->security_parameters.server_ctype = ct;
}

/**
 * gnutls_handshake_set_post_client_hello_function:
 * @session: is a #gnutls_session_t type.
 * @func: is the function to be called
 *
 * This function will set a callback to be called after the client
 * hello has been received (callback valid in server side only). This
 * allows the server to adjust settings based on received extensions.
 *
 * Those settings could be ciphersuites, requesting certificate, or
 * anything else except for version negotiation (this is done before
 * the hello message is parsed).
 *
 * This callback must return 0 on success or a gnutls error code to
 * terminate the handshake.
 *
 * Since GnuTLS 3.3.5 the callback is
 * allowed to return %GNUTLS_E_AGAIN or %GNUTLS_E_INTERRUPTED to
 * put the handshake on hold. In that case gnutls_handshake()
 * will return %GNUTLS_E_INTERRUPTED and can be resumed when needed.
 *
 * Warning: You should not use this function to terminate the
 * handshake based on client input unless you know what you are
 * doing. Before the handshake is finished there is no way to know if
 * there is a man-in-the-middle attack being performed.
 **/
void gnutls_handshake_set_post_client_hello_function(
  gnutls_session_t session, gnutls_handshake_simple_hook_func func)
{
  session->internals.user_hello_func = func;
}

/**
 * gnutls_session_enable_compatibility_mode:
 * @session: is a #gnutls_session_t type.
 *
 * This function can be used to disable certain (security) features in
 * TLS in order to maintain maximum compatibility with buggy
 * clients. Because several trade-offs with security are enabled,
 * if required they will be reported through the audit subsystem.
 *
 * Normally only servers that require maximum compatibility with
 * everything out there, need to call this function.
 *
 * Note that this function must be called after any call to gnutls_priority
 * functions.
 *
 * Since: 2.1.4
 **/
void gnutls_session_enable_compatibility_mode(gnutls_session_t session)
{
  ENABLE_COMPAT(&session->internals);
}

/**
 * gnutls_session_channel_binding:
 * @session: is a #gnutls_session_t type.
 * @cbtype: an #gnutls_channel_binding_t enumeration type
 * @cb: output buffer array with data
 *
 * Extract given channel binding data of the @cbtype (e.g.,
 * %GNUTLS_CB_TLS_UNIQUE) type.
 *
 * Returns: %GNUTLS_E_SUCCESS on success,
 * %GNUTLS_E_UNIMPLEMENTED_FEATURE if the @cbtype is unsupported,
 * %GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLE if the data is not
 * currently available, or an error code.
 *
 * Since: 2.12.0
 **/
int gnutls_session_channel_binding(gnutls_session_t session,
           gnutls_channel_binding_t cbtype,
           gnutls_datum_t *cb)
{
  if (!session->internals.initial_negotiation_completed)
    return GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLE;

  if (cbtype == GNUTLS_CB_TLS_UNIQUE) {
    const version_entry_st *ver = get_version(session);
    if (unlikely(ver == NULL || ver->tls13_sem))
      return GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLE;

    cb->size = session->internals.cb_tls_unique_len;
    cb->data = gnutls_malloc(cb->size);
    if (cb->data == NULL)
      return GNUTLS_E_MEMORY_ERROR;

    memcpy(cb->data, session->internals.cb_tls_unique, cb->size);

    return 0;
  }

  if (cbtype == GNUTLS_CB_TLS_SERVER_END_POINT) {
    const gnutls_datum_t *ders;
    unsigned int num_certs = 1;
    int ret;
    size_t rlen;
    gnutls_x509_crt_t cert;
    gnutls_digest_algorithm_t algo;

    /* Only X509 certificates are supported for this binding type */
    ret = gnutls_certificate_type_get(session);
    if (ret != GNUTLS_CRT_X509)
      return GNUTLS_E_UNIMPLEMENTED_FEATURE;

    if (session->security_parameters.entity == GNUTLS_CLIENT)
      ders = gnutls_certificate_get_peers(session,
                  &num_certs);
    else
      ders = gnutls_certificate_get_ours(session);

    /* Previous check indicated we have x509 but you never know */
    if (!ders || num_certs == 0)
      return GNUTLS_E_UNIMPLEMENTED_FEATURE;

    ret = gnutls_x509_crt_list_import(&cert, &num_certs, ders,
              GNUTLS_X509_FMT_DER, 0);
    /* Again, this is not supposed to happen (normally) */
    if (ret < 0 || num_certs == 0)
      return GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLE;

    /* Obtain signature algorithm used by certificate */
    ret = gnutls_x509_crt_get_signature_algorithm(cert);
    if (ret < 0 || ret == GNUTLS_SIGN_UNKNOWN)
      return GNUTLS_E_UNIMPLEMENTED_FEATURE;

    /* obtain hash function from signature and normalize it */
    algo = gnutls_sign_get_hash_algorithm(ret);
    switch (algo) {
    case GNUTLS_DIG_MD5:
    case GNUTLS_DIG_SHA1:
      algo = GNUTLS_DIG_SHA256;
      break;
    case GNUTLS_DIG_UNKNOWN:
    case GNUTLS_DIG_NULL:
    case GNUTLS_DIG_MD5_SHA1:
      /* double hashing not supported either */
      gnutls_x509_crt_deinit(cert);
      return GNUTLS_E_UNIMPLEMENTED_FEATURE;
    default:
      break;
    }

    /* preallocate 512 bits buffer as maximum supported digest */
    rlen = MAX_HASH_SIZE;
    cb->data = gnutls_malloc(rlen);
    if (cb->data == NULL) {
      gnutls_x509_crt_deinit(cert);
      return GNUTLS_E_MEMORY_ERROR;
    }

    ret = gnutls_x509_crt_get_fingerprint(cert, algo, cb->data,
                  &rlen);
    if (ret == GNUTLS_E_SHORT_MEMORY_BUFFER) {
      cb->data = gnutls_realloc_fast(cb->data, cb->size);
      if (cb->data == NULL) {
        gnutls_x509_crt_deinit(cert);
        return GNUTLS_E_MEMORY_ERROR;
      }
      ret = gnutls_x509_crt_get_fingerprint(cert, algo,
                    cb->data, &rlen);
    }
    cb->size = rlen;
    gnutls_x509_crt_deinit(cert);
    return ret;
  }

  if (cbtype == GNUTLS_CB_TLS_EXPORTER) {
#define RFC5705_LABEL_DATA "EXPORTER-Channel-Binding"
#define RFC5705_LABEL_LEN 24
#define EXPORTER_CTX_DATA ""
#define EXPORTER_CTX_LEN 0

    const version_entry_st *ver = get_version(session);
    if (unlikely(ver == NULL)) {
      return GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLE;
    }

    /* "tls-exporter" channel binding is defined only when
     * the TLS handshake results in unique master secrets,
     * i.e., either TLS 1.3, or TLS 1.2 with extended
     * master secret negotiated.
     */
    if (!ver->tls13_sem &&
        gnutls_session_ext_master_secret_status(session) == 0) {
      return GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLE;
    }

    cb->size = 32;
    cb->data = gnutls_malloc(cb->size);
    if (cb->data == NULL)
      return GNUTLS_E_MEMORY_ERROR;

    return gnutls_prf_rfc5705(session, RFC5705_LABEL_LEN,
            RFC5705_LABEL_DATA, EXPORTER_CTX_LEN,
            EXPORTER_CTX_DATA, cb->size,
            (char *)cb->data);
  }

  return GNUTLS_E_UNIMPLEMENTED_FEATURE;
}

/**
 * gnutls_ecc_curve_get:
 * @session: is a #gnutls_session_t type.
 *
 * Returns the currently used elliptic curve for key exchange. Only valid
 * when using an elliptic curve ciphersuite.
 *
 * Returns: the currently used curve, a #gnutls_ecc_curve_t
 *   type.
 *
 * Since: 3.0
 **/
gnutls_ecc_curve_t gnutls_ecc_curve_get(gnutls_session_t session)
{
  const gnutls_group_entry_st *e;

  e = get_group(session);
  if (e == NULL || e->curve == 0)
    return 0;
  return e->curve;
}

/**
 * gnutls_group_get:
 * @session: is a #gnutls_session_t type.
 *
 * Returns the currently used group for key exchange. Only valid
 * when using an elliptic curve or DH ciphersuite.
 *
 * Returns: the currently used group, a #gnutls_group_t
 *   type.
 *
 * Since: 3.6.0
 **/
gnutls_group_t gnutls_group_get(gnutls_session_t session)
{
  const gnutls_group_entry_st *e;

  e = get_group(session);
  if (e == NULL)
    return 0;
  return e->id;
}

/**
 * gnutls_protocol_get_version:
 * @session: is a #gnutls_session_t type.
 *
 * Get TLS version, a #gnutls_protocol_t value.
 *
 * Returns: The version of the currently used protocol.
 **/
gnutls_protocol_t gnutls_protocol_get_version(gnutls_session_t session)
{
  return get_num_version(session);
}

/**
 * gnutls_session_get_random:
 * @session: is a #gnutls_session_t type.
 * @client: the client part of the random
 * @server: the server part of the random
 *
 * This function returns pointers to the client and server
 * random fields used in the TLS handshake. The pointers are
 * not to be modified or deallocated.
 *
 * If a client random value has not yet been established, the output
 * will be garbage.
 *
 * Since: 3.0
 **/
void gnutls_session_get_random(gnutls_session_t session, gnutls_datum_t *client,
             gnutls_datum_t *server)
{
  if (client) {
    client->data = session->security_parameters.client_random;
    client->size =
      sizeof(session->security_parameters.client_random);
  }

  if (server) {
    server->data = session->security_parameters.server_random;
    server->size =
      sizeof(session->security_parameters.server_random);
  }
}

/**
 * gnutls_session_get_master_secret:
 * @session: is a #gnutls_session_t type.
 * @secret: the session's master secret
 *
 * This function returns pointers to the master secret
 * used in the TLS session. The pointers are not to be modified or deallocated.
 *
 * This function is only applicable under TLS 1.2 or earlier versions.
 *
 * Since: 3.5.0
 **/
void gnutls_session_get_master_secret(gnutls_session_t session,
              gnutls_datum_t *secret)
{
  secret->data = session->security_parameters.master_secret;
  secret->size = sizeof(session->security_parameters.master_secret);
}

unsigned int timespec_sub_ms(struct timespec *a, struct timespec *b)
{
  time_t dsecs;

  dsecs = a->tv_sec - b->tv_sec;
  if (!INT_MULTIPLY_OVERFLOW(dsecs, 1000)) {
    return (dsecs * 1000 +
      (a->tv_nsec - b->tv_nsec) / (1000 * 1000));
  } else {
    return UINT_MAX;
  }
}

/**
 * gnutls_handshake_set_random:
 * @session: is a #gnutls_session_t type.
 * @random: a random value of 32-bytes
 *
 * This function will explicitly set the server or client hello 
 * random value in the subsequent TLS handshake. The random value 
 * should be a 32-byte value.
 *
 * Note that this function should not normally be used as gnutls
 * will select automatically a random value for the handshake.
 *
 * This function should not be used when resuming a session.
 *
 * Returns: %GNUTLS_E_SUCCESS on success, or an error code.
 *
 * Since 3.1.9
 **/
int gnutls_handshake_set_random(gnutls_session_t session,
        const gnutls_datum_t *random)
{
  if (random->size != GNUTLS_RANDOM_SIZE)
    return GNUTLS_E_INVALID_REQUEST;

  session->internals.sc_random_set = 1;
  if (session->security_parameters.entity == GNUTLS_CLIENT)
    memcpy(session->internals.resumed_security_parameters
             .client_random,
           random->data, random->size);
  else
    memcpy(session->internals.resumed_security_parameters
             .server_random,
           random->data, random->size);

  return 0;
}

/**
 * gnutls_handshake_set_hook_function:
 * @session: is a #gnutls_session_t type
 * @htype: the %gnutls_handshake_description_t of the message to hook at
 * @when: %GNUTLS_HOOK_* depending on when the hook function should be called
 * @func: is the function to be called
 *
 * This function will set a callback to be called after or before the specified
 * handshake message has been received or generated. This is a
 * generalization of gnutls_handshake_set_post_client_hello_function().
 *
 * To call the hook function prior to the message being generated or processed
 * use %GNUTLS_HOOK_PRE as @when parameter, %GNUTLS_HOOK_POST to call
 * after, and %GNUTLS_HOOK_BOTH for both cases.
 *
 * This callback must return 0 on success or a gnutls error code to
 * terminate the handshake.
 *
 * To hook at all handshake messages use an @htype of %GNUTLS_HANDSHAKE_ANY.
 *
 * Warning: You should not use this function to terminate the
 * handshake based on client input unless you know what you are
 * doing. Before the handshake is finished there is no way to know if
 * there is a man-in-the-middle attack being performed.
 **/
void gnutls_handshake_set_hook_function(gnutls_session_t session,
          unsigned int htype, int when,
          gnutls_handshake_hook_func func)
{
  session->internals.h_hook = func;
  session->internals.h_type = htype;
  session->internals.h_post = when;
}

/**
 * gnutls_handshake_set_read_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 handshake
 * message is being sent.
 *
 * Since: 3.7.0
 */
void gnutls_handshake_set_read_function(gnutls_session_t session,
          gnutls_handshake_read_func func)
{
  session->internals.h_read_func = func;
}

/**
 * gnutls_alert_set_read_function:
 * @session: is #gnutls_session_t type
 * @func: is the function to be called
 *
 * This function will set a callback to be called when an alert
 * message is being sent.
 *
 * Since: 3.7.0
 */
void gnutls_alert_set_read_function(gnutls_session_t session,
            gnutls_alert_read_func func)
{
  session->internals.alert_read_func = func;
}

/**
 * gnutls_record_get_state:
 * @session: is a #gnutls_session_t type
 * @read: if non-zero the read parameters are returned, otherwise the write
 * @mac_key: the key used for MAC (if a MAC is used)
 * @IV: the initialization vector or nonce used
 * @cipher_key: the cipher key
 * @seq_number: A 64-bit sequence number
 *
 * This function will return the parameters of the current record state.
 * These are only useful to be provided to an external off-loading device
 * or subsystem. The returned values should be considered constant
 * and valid for the lifetime of the session.
 *
 * In that case, to sync the state back you must call gnutls_record_set_state().
 *
 * Returns: %GNUTLS_E_SUCCESS on success, or an error code.
 *
 * Since 3.4.0
 **/
int gnutls_record_get_state(gnutls_session_t session, unsigned read,
          gnutls_datum_t *mac_key, gnutls_datum_t *IV,
          gnutls_datum_t *cipher_key,
          unsigned char seq_number[8])
{
  record_parameters_st *record_params;
  record_state_st *record_state;
  unsigned int epoch;
  int ret;

  if (read)
    epoch = EPOCH_READ_CURRENT;
  else
    epoch = EPOCH_WRITE_CURRENT;

  ret = _gnutls_epoch_get(session, epoch, &record_params);
  if (ret < 0)
    return gnutls_assert_val(ret);

  if (!record_params->initialized)
    return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

  if (read)
    record_state = &record_params->read;
  else
    record_state = &record_params->write;

  if (mac_key) {
    mac_key->data = record_state->mac_key;
    mac_key->size = record_state->mac_key_size;
  }

  if (IV) {
    IV->data = record_state->iv;
    IV->size = record_state->iv_size;
  }

  if (cipher_key) {
    cipher_key->data = record_state->key;
    cipher_key->size = record_state->key_size;
  }

  if (seq_number)
    _gnutls_write_uint64(record_state->sequence_number, seq_number);
  return 0;
}

/**
 * gnutls_record_set_state:
 * @session: is a #gnutls_session_t type
 * @read: if non-zero the read parameters are returned, otherwise the write
 * @seq_number: A 64-bit sequence number
 *
 * This function will set the sequence number in the current record state.
 * This function is useful if sending and receiving are offloaded from
 * gnutls. That is, if gnutls_record_get_state() was used.
 *
 * Returns: %GNUTLS_E_SUCCESS on success, or an error code.
 *
 * Since 3.4.0
 **/
int gnutls_record_set_state(gnutls_session_t session, unsigned read,
          const unsigned char seq_number[8])
{
  record_parameters_st *record_params;
  record_state_st *record_state;
  int epoch, ret;

  if (read)
    epoch = EPOCH_READ_CURRENT;
  else
    epoch = EPOCH_WRITE_CURRENT;

  ret = _gnutls_epoch_get(session, epoch, &record_params);
  if (ret < 0)
    return gnutls_assert_val(ret);

  if (!record_params->initialized)
    return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

  if (read)
    record_state = &record_params->read;
  else
    record_state = &record_params->write;

  record_state->sequence_number = _gnutls_read_uint64(seq_number);

  if (IS_DTLS(session)) {
    _dtls_reset_window(record_params);
  }

  return 0;
}

/**
 * gnutls_session_get_flags:
 * @session: is a #gnutls_session_t type.
 *
 * This function will return a series (ORed) of flags, applicable
 * for the current session.
 *
 * This replaces individual informational functions such as
 * gnutls_safe_renegotiation_status(), gnutls_session_ext_master_secret_status(),
 * etc.
 *
 * Returns: An ORed sequence of flags (see %gnutls_session_flags_t)
 *
 * Since: 3.5.0
 **/
unsigned gnutls_session_get_flags(gnutls_session_t session)
{
  unsigned flags = 0;

  if (gnutls_safe_renegotiation_status(session))
    flags |= GNUTLS_SFLAGS_SAFE_RENEGOTIATION;
  if (gnutls_session_ext_master_secret_status(session))
    flags |= GNUTLS_SFLAGS_EXT_MASTER_SECRET;
  if (gnutls_session_etm_status(session))
    flags |= GNUTLS_SFLAGS_ETM;
  if (gnutls_heartbeat_allowed(session, GNUTLS_HB_LOCAL_ALLOWED_TO_SEND))
    flags |= GNUTLS_SFLAGS_HB_LOCAL_SEND;
  if (gnutls_heartbeat_allowed(session, GNUTLS_HB_PEER_ALLOWED_TO_SEND))
    flags |= GNUTLS_SFLAGS_HB_PEER_SEND;
  if (session->internals.hsk_flags & HSK_FALSE_START_USED)
    flags |= GNUTLS_SFLAGS_FALSE_START;
  if ((session->internals.hsk_flags & HSK_EARLY_START_USED) &&
      (session->internals.flags & GNUTLS_ENABLE_EARLY_START))
    flags |= GNUTLS_SFLAGS_EARLY_START;
  if (session->internals.hsk_flags & HSK_USED_FFDHE)
    flags |= GNUTLS_SFLAGS_RFC7919;
  if (session->internals.hsk_flags & HSK_TICKET_RECEIVED)
    flags |= GNUTLS_SFLAGS_SESSION_TICKET;
  if (session->security_parameters.post_handshake_auth)
    flags |= GNUTLS_SFLAGS_POST_HANDSHAKE_AUTH;
  if (session->internals.hsk_flags & HSK_EARLY_DATA_ACCEPTED)
    flags |= GNUTLS_SFLAGS_EARLY_DATA;
  if (session->internals.hsk_flags & HSK_OCSP_REQUESTED)
    flags |= GNUTLS_SFLAGS_CLI_REQUESTED_OCSP;
  if (session->internals.hsk_flags & HSK_CLIENT_OCSP_REQUESTED)
    flags |= GNUTLS_SFLAGS_SERV_REQUESTED_OCSP;

  return flags;
}

Coverage Report

Created: 2025-03-06 06:58