/src/gnutls/lib/x509/x509.c

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/*
 * Copyright (C) 2003-2018 Free Software Foundation, Inc.
 * Copyright (C) 2018 Red Hat, Inc.
 *
 * Authors: Nikos Mavrogiannopoulos, Simon Josefsson, Howard Chu
 *
 * 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 on X.509 Certificate parsing
 */

#include "gnutls_int.h"
#include "datum.h"
#include "global.h"
#include "errors.h"
#include "common.h"
#include <gnutls/x509-ext.h>
#include "x509.h"
#include "x509_b64.h"
#include "x509_int.h"
#include <libtasn1.h>
#include "pk.h"
#include "pkcs11_int.h"
#include "urls.h"
#include "system-keys.h"
#include "hash.h"
#include "hash-pjw-bare.h"

static int crt_reinit(gnutls_x509_crt_t crt)
{
  int result;

  _gnutls_free_datum(&crt->der);
  crt->raw_dn.size = 0;
  crt->raw_issuer_dn.size = 0;
  crt->raw_spki.size = 0;

  asn1_delete_structure(&crt->cert);

  result = asn1_create_element(_gnutls_get_pkix(), "PKIX1.Certificate",
             &crt->cert);
  if (result != ASN1_SUCCESS) {
    result = _gnutls_asn2err(result);
    gnutls_assert();
    return result;
  }

  gnutls_subject_alt_names_deinit(crt->san);
  result = gnutls_subject_alt_names_init(&crt->san);
  if (result < 0) {
    gnutls_assert();
    return result;
  }

  gnutls_subject_alt_names_deinit(crt->ian);
  result = gnutls_subject_alt_names_init(&crt->ian);
  if (result < 0) {
    gnutls_assert();
    return result;
  }

  return 0;
}

/**
 * gnutls_x509_crt_equals - This function compares two gnutls_x509_crt_t certificates
 * @cert1: The first certificate
 * @cert2: The second certificate
 *
 * This function will compare two X.509 certificate structures.
 *
 * Returns: On equality non-zero is returned, otherwise zero.
 *
 * Since: 3.5.0
 **/
unsigned gnutls_x509_crt_equals(gnutls_x509_crt_t cert1,
        gnutls_x509_crt_t cert2)
{
  int ret;
  bool result;

  if (cert1->modified == 0 && cert2->modified == 0 &&
      cert1->raw_dn.size > 0 && cert2->raw_dn.size > 0) {
    ret = _gnutls_is_same_dn(cert1, cert2);
    if (ret == 0)
      return 0;
  }

  if (cert1->der.size == 0 || cert2->der.size == 0 ||
      cert1->modified != 0 || cert2->modified != 0) {
    gnutls_datum_t tmp1, tmp2;

    /* on uninitialized or modified certificates, we have to re-encode */
    ret = gnutls_x509_crt_export2(cert1, GNUTLS_X509_FMT_DER,
                &tmp1);
    if (ret < 0)
      return gnutls_assert_val(0);

    ret = gnutls_x509_crt_export2(cert2, GNUTLS_X509_FMT_DER,
                &tmp2);
    if (ret < 0) {
      gnutls_free(tmp1.data);
      return gnutls_assert_val(0);
    }

    if ((tmp1.size == tmp2.size) &&
        (memcmp(tmp1.data, tmp2.data, tmp1.size) == 0))
      result = 1;
    else
      result = 0;

    gnutls_free(tmp1.data);
    gnutls_free(tmp2.data);
  } else {
    if ((cert1->der.size == cert2->der.size) &&
        (memcmp(cert1->der.data, cert2->der.data,
          cert1->der.size) == 0))
      result = 1;
    else
      result = 0;
  }

  return result;
}

/**
 * gnutls_x509_crt_equals2 - This function compares a gnutls_x509_crt_t cert with DER data
 * @cert1: The first certificate
 * @der: A DER encoded certificate
 *
 * This function will compare an X.509 certificate structures, with DER
 * encoded certificate data.
 *
 * Returns: On equality non-zero is returned, otherwise zero.
 *
 * Since: 3.5.0
 **/
unsigned gnutls_x509_crt_equals2(gnutls_x509_crt_t cert1,
         const gnutls_datum_t *der)
{
  bool result;

  if (cert1 == NULL || der == NULL)
    return 0;

  if (cert1->der.size == 0 || cert1->modified) {
    gnutls_datum_t tmp1;
    int ret;

    /* on uninitialized or modified certificates, we have to re-encode */
    ret = gnutls_x509_crt_export2(cert1, GNUTLS_X509_FMT_DER,
                &tmp1);
    if (ret < 0)
      return gnutls_assert_val(0);

    if ((tmp1.size == der->size) &&
        (memcmp(tmp1.data, der->data, tmp1.size) == 0))
      result = 1;
    else
      result = 0;

    gnutls_free(tmp1.data);
  } else {
    if ((cert1->der.size == der->size) &&
        (memcmp(cert1->der.data, der->data, cert1->der.size) == 0))
      result = 1;
    else
      result = 0;
  }

  return result;
}

/**
 * gnutls_x509_crt_init:
 * @cert: A pointer to the type to be initialized
 *
 * This function will initialize an X.509 certificate structure.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int gnutls_x509_crt_init(gnutls_x509_crt_t *cert)
{
  gnutls_x509_crt_t tmp;
  int result;

  *cert = NULL;
  FAIL_IF_LIB_ERROR;

  tmp = gnutls_calloc(1, sizeof(gnutls_x509_crt_int));

  if (!tmp)
    return GNUTLS_E_MEMORY_ERROR;

  result = asn1_create_element(_gnutls_get_pkix(), "PKIX1.Certificate",
             &tmp->cert);
  if (result != ASN1_SUCCESS) {
    gnutls_assert();
    gnutls_free(tmp);
    return _gnutls_asn2err(result);
  }

  result = gnutls_subject_alt_names_init(&tmp->san);
  if (result < 0) {
    gnutls_assert();
    asn1_delete_structure(&tmp->cert);
    gnutls_free(tmp);
    return result;
  }

  result = gnutls_subject_alt_names_init(&tmp->ian);
  if (result < 0) {
    gnutls_assert();
    asn1_delete_structure(&tmp->cert);
    gnutls_subject_alt_names_deinit(tmp->san);
    gnutls_free(tmp);
    return result;
  }

  /* If you add anything here, be sure to check if it has to be added
     to gnutls_x509_crt_import as well. */

  *cert = tmp;

  return 0; /* success */
}

/*-
 * _gnutls_x509_crt_cpy - This function copies a gnutls_x509_crt_t type
 * @dest: The data where to copy
 * @src: The data to be copied
 * @flags: zero or CRT_CPY_FAST
 *
 * This function will copy an X.509 certificate structure.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 -*/
int _gnutls_x509_crt_cpy(gnutls_x509_crt_t dest, gnutls_x509_crt_t src)
{
  int ret;
  gnutls_datum_t tmp;
  unsigned dealloc = 0;

  if (src->der.size == 0 || src->modified) {
    ret = gnutls_x509_crt_export2(src, GNUTLS_X509_FMT_DER, &tmp);
    if (ret < 0)
      return gnutls_assert_val(ret);
    dealloc = 1;
  } else {
    tmp.data = src->der.data;
    tmp.size = src->der.size;
  }

  ret = gnutls_x509_crt_import(dest, &tmp, GNUTLS_X509_FMT_DER);

  if (dealloc) {
    gnutls_free(tmp.data);
  }

  if (ret < 0)
    return gnutls_assert_val(ret);

  return 0;
}

/**
 * gnutls_x509_crt_deinit:
 * @cert: The data to be deinitialized
 *
 * This function will deinitialize a certificate structure.
 **/
void gnutls_x509_crt_deinit(gnutls_x509_crt_t cert)
{
  if (!cert)
    return;

  if (cert->cert)
    asn1_delete_structure(&cert->cert);
  gnutls_free(cert->der.data);
  gnutls_subject_alt_names_deinit(cert->san);
  gnutls_subject_alt_names_deinit(cert->ian);
  gnutls_free(cert);
}

static int compare_sig_algorithm(gnutls_x509_crt_t cert)
{
  int ret, len1, len2, result;
  char oid1[MAX_OID_SIZE];
  char oid2[MAX_OID_SIZE];
  gnutls_datum_t sp1 = { NULL, 0 };
  gnutls_datum_t sp2 = { NULL, 0 };
  unsigned empty1 = 0, empty2 = 0;

  len1 = sizeof(oid1);
  result = asn1_read_value(cert->cert, "signatureAlgorithm.algorithm",
         oid1, &len1);
  if (result != ASN1_SUCCESS) {
    gnutls_assert();
    return _gnutls_asn2err(result);
  }

  len2 = sizeof(oid2);
  result = asn1_read_value(
    cert->cert, "tbsCertificate.signature.algorithm", oid2, &len2);
  if (result != ASN1_SUCCESS) {
    gnutls_assert();
    return _gnutls_asn2err(result);
  }

  if (len1 != len2 || memcmp(oid1, oid2, len1) != 0) {
    _gnutls_debug_log(
      "signatureAlgorithm.algorithm differs from tbsCertificate.signature.algorithm: %s, %s\n",
      oid1, oid2);
    gnutls_assert();
    return GNUTLS_E_CERTIFICATE_ERROR;
  }

  /* compare the parameters */
  ret = _gnutls_x509_read_value(cert->cert,
              "signatureAlgorithm.parameters", &sp1);
  if (ret == GNUTLS_E_ASN1_ELEMENT_NOT_FOUND) {
    empty1 = 1;
  } else if (ret < 0) {
    gnutls_assert();
    return ret;
  }

  ret = _gnutls_x509_read_value(
    cert->cert, "tbsCertificate.signature.parameters", &sp2);
  if (ret == GNUTLS_E_ASN1_ELEMENT_NOT_FOUND) {
    empty2 = 1;
  } else if (ret < 0) {
    gnutls_assert();
    return ret;
  }

  /* handle equally empty parameters with missing parameters */
  if (sp1.size == 2 && memcmp(sp1.data, "\x05\x00", 2) == 0) {
    empty1 = 1;
    _gnutls_free_datum(&sp1);
  }

  if (sp2.size == 2 && memcmp(sp2.data, "\x05\x00", 2) == 0) {
    empty2 = 1;
    _gnutls_free_datum(&sp2);
  }

  if (empty1 != empty2 || sp1.size != sp2.size ||
      (sp1.size > 0 && memcmp(sp1.data, sp2.data, sp1.size) != 0)) {
    gnutls_assert();
    ret = GNUTLS_E_CERTIFICATE_ERROR;
    goto cleanup;
  }

  ret = 0;
cleanup:
  _gnutls_free_datum(&sp1);
  _gnutls_free_datum(&sp2);
  return ret;
}

static int cache_alt_names(gnutls_x509_crt_t cert)
{
  gnutls_datum_t tmpder = { NULL, 0 };
  int ret;

  /* pre-parse subject alt name */
  ret = _gnutls_x509_crt_get_extension(cert, "2.5.29.17", 0, &tmpder,
               NULL);
  if (ret < 0 && ret != GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) {
    gnutls_free(tmpder.data);
    return gnutls_assert_val(ret);
  }

  if (ret >= 0) {
    ret = gnutls_x509_ext_import_subject_alt_names(&tmpder,
                     cert->san, 0);
    gnutls_free(tmpder.data);
    if (ret < 0)
      return gnutls_assert_val(ret);
  }

  ret = _gnutls_x509_crt_get_extension(cert, "2.5.29.18", 0, &tmpder,
               NULL);
  if (ret < 0 && ret != GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
    return gnutls_assert_val(ret);

  if (ret >= 0) {
    ret = gnutls_x509_ext_import_subject_alt_names(&tmpder,
                     cert->ian, 0);
    gnutls_free(tmpder.data);
    if (ret < 0)
      return gnutls_assert_val(ret);
  }

  return 0;
}

static bool hcomparator(const void *v1, const void *v2)
{
  return (strcmp(v1, v2) == 0);
}

static size_t hhasher(const void *entry, size_t n)
{
  const char *e = entry;
  if (e == NULL || e[0] == 0)
    return 0;

  return hash_pjw_bare(e, strlen(e)) % n;
}

#ifdef STRICT_X509

/* Check whether certificates serial number is RFC5280 compliant */
static bool has_valid_serial(gnutls_x509_crt_t cert)
{
  int err, is_zero;
  unsigned i;
  unsigned char serial[128];
  size_t serial_size = sizeof(serial);

  err = gnutls_x509_crt_get_serial(cert, serial, &serial_size);
  if (err < 0) {
    _gnutls_debug_log("error: could not read serial number\n");
    return false;
  }

  if (serial_size > 20) {
    _gnutls_debug_log(
      "error: serial number value is longer than 20 octets\n");
    return false;
  }

  if (serial[0] & 0x80) {
    _gnutls_debug_log("error: serial number is negative\n");
    return false;
  }

  is_zero = 1;
  for (i = 0; i < serial_size; ++i) {
    if (serial[i]) {
      is_zero = 0;
      break;
    }
  }

  if (is_zero) {
    _gnutls_debug_log("error: serial number is zero\n");
    return false;
  }

  return true;
}

/* Check if extension can be successfully parsed */
static bool is_valid_extension(const char *oid, gnutls_datum_t *der)
{
  int err = 0, i;
  unsigned u;
  size_t sz;
  time_t t1, t2;
  char *s1 = NULL, *s2 = NULL;
  gnutls_datum_t datum = { NULL, 0 };

  if (!strcmp(oid, GNUTLS_X509EXT_OID_BASIC_CONSTRAINTS)) {
    err = gnutls_x509_ext_import_basic_constraints(der, &u, &i);
  } else if (!strcmp(oid, GNUTLS_X509EXT_OID_SUBJECT_KEY_ID)) {
    err = gnutls_x509_ext_import_subject_key_id(der, &datum);
  } else if (!strcmp(oid, GNUTLS_X509EXT_OID_CRT_POLICY)) {
    gnutls_x509_policies_t policies;
    if (gnutls_x509_policies_init(&policies) < 0)
      return false;
    err = gnutls_x509_ext_import_policies(der, policies, 0);
    gnutls_x509_policies_deinit(policies);
  } else if (!strcmp(oid, GNUTLS_X509_OID_POLICY_ANY)) {
    err = gnutls_x509_ext_import_inhibit_anypolicy(der, &u);
  } else if (!strcmp(oid, GNUTLS_X509EXT_OID_AUTHORITY_KEY_ID)) {
    gnutls_x509_aki_t aki;
    if (gnutls_x509_aki_init(&aki) < 0)
      return false;
    err = gnutls_x509_ext_import_authority_key_id(der, aki, 0);
    gnutls_x509_aki_deinit(aki);
  } else if (!strcmp(oid, GNUTLS_X509EXT_OID_KEY_USAGE)) {
    err = gnutls_x509_ext_import_key_usage(der, &u);
  } else if (!strcmp(oid, GNUTLS_X509EXT_OID_PRIVATE_KEY_USAGE_PERIOD)) {
    err = gnutls_x509_ext_import_private_key_usage_period(der, &t1,
                      &t2);
  } else if (!strcmp(oid, GNUTLS_X509EXT_OID_EXTENDED_KEY_USAGE)) {
    gnutls_x509_key_purposes_t purposes;
    if (gnutls_x509_key_purpose_init(&purposes) < 0)
      return false;
    err = gnutls_x509_ext_import_key_purposes(der, purposes, 0);
    gnutls_x509_key_purpose_deinit(purposes);
  } else if (!strcmp(oid, GNUTLS_X509EXT_OID_SAN) ||
       !strcmp(oid, GNUTLS_X509EXT_OID_IAN)) {
    gnutls_subject_alt_names_t names;
    if (gnutls_subject_alt_names_init(&names) < 0)
      return false;
    err = gnutls_x509_ext_import_subject_alt_names(der, names, 0);
    gnutls_subject_alt_names_deinit(names);
  } else if (!strcmp(oid, GNUTLS_X509EXT_OID_CRL_DIST_POINTS)) {
    gnutls_x509_crl_dist_points_t dp;
    if (gnutls_x509_crl_dist_points_init(&dp) < 0)
      return false;
    err = gnutls_x509_ext_import_crl_dist_points(der, dp, 0);
    gnutls_x509_crl_dist_points_deinit(dp);
  } else if (!strcmp(oid, GNUTLS_X509EXT_OID_PROXY_CRT_INFO)) {
    err = gnutls_x509_ext_import_proxy(der, &i, &s1, &s2, &sz);
  } else if (!strcmp(oid, GNUTLS_X509EXT_OID_AUTHORITY_INFO_ACCESS)) {
    gnutls_x509_aia_t aia;
    if (gnutls_x509_aia_init(&aia) < 0)
      return false;
    err = gnutls_x509_ext_import_aia(der, aia, 0);
    gnutls_x509_aia_deinit(aia);
  } else if (!strcmp(oid, GNUTLS_X509EXT_OID_CT_SCT_V1)) {
    gnutls_x509_ct_scts_t scts;
    if (gnutls_x509_ext_ct_scts_init(&scts) < 0)
      return false;
    err = gnutls_x509_ext_ct_import_scts(der, scts, 0);
    gnutls_x509_ext_ct_scts_deinit(scts);
  } else if (!strcmp(oid, GNUTLS_X509EXT_OID_NAME_CONSTRAINTS)) {
    gnutls_x509_name_constraints_t nc;
    if (gnutls_x509_name_constraints_init(&nc) < 0)
      return false;
    err = gnutls_x509_ext_import_name_constraints(der, nc, 0);
    gnutls_x509_name_constraints_deinit(nc);
  } else if (!strcmp(oid, GNUTLS_X509EXT_OID_TLSFEATURES)) {
    gnutls_x509_tlsfeatures_t features;
    if (gnutls_x509_tlsfeatures_init(&features) < 0)
      return false;
    err = gnutls_x509_ext_import_tlsfeatures(der, features, 0);
    gnutls_x509_tlsfeatures_deinit(features);
  } else {
    return true;
  }

  gnutls_free(s1);
  gnutls_free(s2);
  _gnutls_free_datum(&datum);

  return err == 0;
}

#endif /* STRICT_X509 */

int _gnutls_check_cert_sanity(gnutls_x509_crt_t cert)
{
  int ret = 0, version;
  gnutls_datum_t exts;
  Hash_table *htable = NULL;

  if (cert->flags & GNUTLS_X509_CRT_FLAG_IGNORE_SANITY)
    return 0;

  /* enforce the rule that only version 3 certificates carry extensions */
  ret = gnutls_x509_crt_get_version(cert);
  if (ret < 0) {
    return gnutls_assert_val(ret);
  }

  version = ret;

#ifdef STRICT_X509
  /* enforce upper bound on certificate version (RFC5280 compliant) */
  if (version > 3) {
    _gnutls_debug_log("error: invalid certificate version %d\n",
          version);
    return gnutls_assert_val(GNUTLS_E_X509_CERTIFICATE_ERROR);
  }
#endif

  if (version < 3) {
    if (!cert->modified) {
      ret = _gnutls_x509_get_raw_field2(
        cert->cert, &cert->der,
        "tbsCertificate.extensions", &exts);
      if (ret >= 0 && exts.size > 0) {
        _gnutls_debug_log(
          "error: extensions present in certificate with version %d\n",
          version);
        return gnutls_assert_val(
          GNUTLS_E_X509_CERTIFICATE_ERROR);
      }
    } else {
      if (cert->use_extensions) {
        _gnutls_debug_log(
          "error: extensions set in certificate with version %d\n",
          version);
        return gnutls_assert_val(
          GNUTLS_E_X509_CERTIFICATE_ERROR);
      }
    }
  } else {
    /* Version is 3; ensure no duplicate extensions are present. */
    unsigned i, critical;
    char oid[MAX_OID_SIZE];
    size_t oid_size;
    char *o;

    htable = hash_initialize(16, NULL, hhasher, hcomparator,
           gnutls_free);
    if (htable == NULL)
      return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

    for (i = 0;; i++) {
      oid_size = sizeof(oid);
      ret = gnutls_x509_crt_get_extension_info(
        cert, i, oid, &oid_size, &critical);
      if (ret < 0) {
        if (ret ==
            GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
          break;
        gnutls_assert();
        goto cleanup;
      }
      o = gnutls_strdup(oid);
      if (o == NULL) {
        ret = gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);
        goto cleanup;
      }

      ret = hash_insert_if_absent(htable, o, NULL);
      if (ret == -1) {
        gnutls_free(o);
        ret = gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);
        goto cleanup;
      } else if (ret == 0) {
        /* duplicate */
        gnutls_free(o);
        _gnutls_debug_log(
          "error: duplicate extension (%s) detected\n",
          oid);
        ret = gnutls_assert_val(
          GNUTLS_E_X509_DUPLICATE_EXTENSION);
        goto cleanup;
      }

#ifdef STRICT_X509
      gnutls_datum_t der = { NULL, 0 };
      ret = gnutls_x509_crt_get_extension_data2(cert, i,
                  &der);
      if (ret < 0)
        continue;
      if (critical && !is_valid_extension(oid, &der)) {
        _gnutls_free_datum(&der);
        _gnutls_debug_log(
          "error: could not parse extension (%s)\n");
        return gnutls_assert_val(
          GNUTLS_E_X509_CERTIFICATE_ERROR);
      }
      _gnutls_free_datum(&der);
#endif
    }

    hash_free(htable);
    htable = NULL;
  }

  if (version < 2) {
    char id[128];
    size_t id_size;

    id_size = sizeof(id);
    ret = gnutls_x509_crt_get_subject_unique_id(cert, id, &id_size);
    if (ret >= 0 || ret == GNUTLS_E_SHORT_MEMORY_BUFFER) {
      _gnutls_debug_log(
        "error: subjectUniqueID present in certificate with version %d\n",
        version);
      ret = gnutls_assert_val(
        GNUTLS_E_X509_CERTIFICATE_ERROR);
      goto cleanup;
    }

    id_size = sizeof(id);
    ret = gnutls_x509_crt_get_issuer_unique_id(cert, id, &id_size);
    if (ret >= 0 || ret == GNUTLS_E_SHORT_MEMORY_BUFFER) {
      _gnutls_debug_log(
        "error: subjectUniqueID present in certificate with version %d\n",
        version);
      ret = gnutls_assert_val(
        GNUTLS_E_X509_CERTIFICATE_ERROR);
      goto cleanup;
    }
  }

#ifdef STRICT_X509
  if (!has_valid_serial(cert)) {
    ret = gnutls_assert_val(GNUTLS_E_X509_CERTIFICATE_ERROR);
    goto cleanup;
  }
#endif

  if (gnutls_x509_crt_get_expiration_time(cert) == -1 ||
      gnutls_x509_crt_get_activation_time(cert) == -1) {
    _gnutls_debug_log(
      "error: invalid expiration or activation time in certificate\n");
    ret = gnutls_assert_val(GNUTLS_E_CERTIFICATE_TIME_ERROR);
    goto cleanup;
  }

  ret = 0;

cleanup:
  if (htable)
    hash_free(htable);
  return ret;
}

/**
 * gnutls_x509_crt_import:
 * @cert: The data to store the parsed certificate.
 * @data: The DER or PEM encoded certificate.
 * @format: One of DER or PEM
 *
 * This function will convert the given DER or PEM encoded Certificate
 * to the native gnutls_x509_crt_t format. The output will be stored
 * in @cert.
 *
 * If the Certificate is PEM encoded it should have a header of "X509
 * CERTIFICATE", or "CERTIFICATE".
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int gnutls_x509_crt_import(gnutls_x509_crt_t cert, const gnutls_datum_t *data,
         gnutls_x509_crt_fmt_t format)
{
  int result;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  if (cert->expanded) {
    /* Any earlier _asn1_strict_der_decode will modify the ASN.1
       structure, so we need to replace it with a fresh
       structure. */
    result = crt_reinit(cert);
    if (result < 0) {
      gnutls_assert();
      goto cleanup;
    }
  }

  /* If the Certificate is in PEM format then decode it
   */
  if (format == GNUTLS_X509_FMT_PEM) {
    /* Try the first header */
    result = _gnutls_fbase64_decode(PEM_X509_CERT2, data->data,
            data->size, &cert->der);

    if (result < 0) {
      /* try for the second header */
      result = _gnutls_fbase64_decode(PEM_X509_CERT,
              data->data, data->size,
              &cert->der);

      if (result < 0) {
        gnutls_assert();
        return result;
      }
    }
  } else {
    result = _gnutls_set_datum(&cert->der, data->data, data->size);
    if (result < 0) {
      gnutls_assert();
      return result;
    }
  }

  cert->expanded = 1;
  cert->modified = 0;

  result = _asn1_strict_der_decode(&cert->cert, cert->der.data,
           cert->der.size, NULL);
  if (result != ASN1_SUCCESS) {
    result = _gnutls_asn2err(result);
    gnutls_assert();
    goto cleanup;
  }

  result = compare_sig_algorithm(cert);
  if (result < 0) {
    gnutls_assert();
    goto cleanup;
  }

  /* The following do not allocate but rather point to DER data */
  result = _gnutls_x509_get_raw_field2(
    cert->cert, &cert->der, "tbsCertificate.issuer.rdnSequence",
    &cert->raw_issuer_dn);
  if (result < 0) {
    gnutls_assert();
    goto cleanup;
  }

  result = _gnutls_x509_get_raw_field2(
    cert->cert, &cert->der, "tbsCertificate.subject.rdnSequence",
    &cert->raw_dn);
  if (result < 0) {
    gnutls_assert();
    goto cleanup;
  }

  result = _gnutls_x509_get_raw_field2(
    cert->cert, &cert->der, "tbsCertificate.subjectPublicKeyInfo",
    &cert->raw_spki);
  if (result < 0) {
    gnutls_assert();
    goto cleanup;
  }

  result = cache_alt_names(cert);
  if (result < 0) {
    gnutls_assert();
    goto cleanup;
  }

  result = _gnutls_check_cert_sanity(cert);
  if (result < 0) {
    gnutls_assert();
    goto cleanup;
  }

  /* Since we do not want to disable any extension
   */
  cert->use_extensions = 1;

  return 0;

cleanup:
  _gnutls_free_datum(&cert->der);
  return result;
}

/**
 * gnutls_x509_crt_get_issuer_dn:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @buf: a pointer to a structure to hold the name (may be null)
 * @buf_size: initially holds the size of @buf
 *
 * This function will copy the name of the Certificate issuer in the
 * provided buffer. The name will be in the form
 * "C=xxxx,O=yyyy,CN=zzzz" as described in RFC4514. The output string
 * will be ASCII or UTF-8 encoded, depending on the certificate data.
 *
 * If @buf is null then only the size will be filled.
 *
 * This function does not output a fully RFC4514 compliant string, if
 * that is required see gnutls_x509_crt_get_issuer_dn3().
 *
 * Returns: %GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not
 *   long enough, and in that case the @buf_size will be updated
 *   with the required size. %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE if
 *   the DN does not exist, or another error value on error. On success 0 is returned.
 **/
int gnutls_x509_crt_get_issuer_dn(gnutls_x509_crt_t cert, char *buf,
          size_t *buf_size)
{
  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  return _gnutls_x509_parse_dn(cert->cert,
             "tbsCertificate.issuer.rdnSequence", buf,
             buf_size, GNUTLS_X509_DN_FLAG_COMPAT);
}

/**
 * gnutls_x509_crt_get_issuer_dn2:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @dn: a pointer to a structure to hold the name; must be freed using gnutls_free()
 *
 * This function will allocate buffer and copy the name of issuer of the Certificate.
 * The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
 * described in RFC4514. The output string will be ASCII or UTF-8
 * encoded, depending on the certificate data.
 *
 * This function does not output a fully RFC4514 compliant string, if
 * that is required see gnutls_x509_crt_get_issuer_dn3().
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 *
 * Since: 3.1.10
 **/
int gnutls_x509_crt_get_issuer_dn2(gnutls_x509_crt_t cert, gnutls_datum_t *dn)
{
  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  return _gnutls_x509_get_dn(cert->cert,
           "tbsCertificate.issuer.rdnSequence", dn,
           GNUTLS_X509_DN_FLAG_COMPAT);
}

/**
 * gnutls_x509_crt_get_issuer_dn3:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @dn: a pointer to a structure to hold the name; must be freed using gnutls_free()
 * @flags: zero or %GNUTLS_X509_DN_FLAG_COMPAT
 *
 * This function will allocate buffer and copy the name of issuer of the Certificate.
 * The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
 * described in RFC4514. The output string will be ASCII or UTF-8
 * encoded, depending on the certificate data.
 *
 * When the flag %GNUTLS_X509_DN_FLAG_COMPAT is specified, the output
 * format will match the format output by previous to 3.5.6 versions of GnuTLS
 * which was not not fully RFC4514-compliant.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 *
 * Since: 3.5.7
 **/
int gnutls_x509_crt_get_issuer_dn3(gnutls_x509_crt_t cert, gnutls_datum_t *dn,
           unsigned flags)
{
  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  return _gnutls_x509_get_dn(
    cert->cert, "tbsCertificate.issuer.rdnSequence", dn, flags);
}

/**
 * gnutls_x509_crt_get_issuer_dn_by_oid:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @oid: holds an Object Identified in null terminated string
 * @indx: In case multiple same OIDs exist in the RDN, this specifies which to send. Use (0) to get the first one.
 * @raw_flag: If non-zero returns the raw DER data of the DN part.
 * @buf: a pointer to a structure to hold the name (may be null)
 * @buf_size: initially holds the size of @buf
 *
 * This function will extract the part of the name of the Certificate
 * issuer specified by the given OID. The output, if the raw flag is not
 * used, will be encoded as described in RFC4514. Thus a string that is
 * ASCII or UTF-8 encoded, depending on the certificate data.
 *
 * Some helper macros with popular OIDs can be found in gnutls/x509.h
 * If raw flag is (0), this function will only return known OIDs as
 * text. Other OIDs will be DER encoded, as described in RFC4514 --
 * in hex format with a '#' prefix.  You can check about known OIDs
 * using gnutls_x509_dn_oid_known().
 *
 * If @buf is null then only the size will be filled. If the @raw_flag
 * is not specified the output is always null terminated, although the
 * @buf_size will not include the null character.
 *
 * Returns: %GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not
 *   long enough, and in that case the @buf_size will be updated with
 *   the required size. %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE if there
 *   are no data in the current index. On success 0 is returned.
 **/
int gnutls_x509_crt_get_issuer_dn_by_oid(gnutls_x509_crt_t cert,
           const char *oid, unsigned indx,
           unsigned int raw_flag, void *buf,
           size_t *buf_size)
{
  gnutls_datum_t td;
  int ret;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  ret = _gnutls_x509_parse_dn_oid(cert->cert,
          "tbsCertificate.issuer.rdnSequence",
          oid, indx, raw_flag, &td);
  if (ret < 0)
    return gnutls_assert_val(ret);

  return _gnutls_strdatum_to_buf(&td, buf, buf_size);
}

/**
 * gnutls_x509_crt_get_issuer_dn_oid:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @indx: This specifies which OID to return. Use (0) to get the first one.
 * @oid: a pointer to a buffer to hold the OID (may be null)
 * @oid_size: initially holds the size of @oid
 *
 * This function will extract the OIDs of the name of the Certificate
 * issuer specified by the given index.
 *
 * If @oid is null then only the size will be filled. The @oid
 * returned will be null terminated, although @oid_size will not
 * account for the trailing null.
 *
 * Returns: %GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not
 *   long enough, and in that case the @buf_size will be updated with
 *   the required size. %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE if there
 *   are no data in the current index. On success 0 is returned.
 **/
int gnutls_x509_crt_get_issuer_dn_oid(gnutls_x509_crt_t cert, unsigned indx,
              void *oid, size_t *oid_size)
{
  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  return _gnutls_x509_get_dn_oid(cert->cert,
               "tbsCertificate.issuer.rdnSequence",
               indx, oid, oid_size);
}

/**
 * gnutls_x509_crt_get_dn:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @buf: a pointer to a structure to hold the name (may be null)
 * @buf_size: initially holds the size of @buf
 *
 * This function will copy the name of the Certificate in the provided
 * buffer. The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
 * described in RFC4514. The output string will be ASCII or UTF-8
 * encoded, depending on the certificate data.
 *
 * The @buf returned will be null terminated and the @buf_size will account
 * for the trailing null. If @buf is null then only the size will be filled.
 *
 * This function does not output a fully RFC4514 compliant string, if
 * that is required see gnutls_x509_crt_get_dn3().
 *
 * Returns: %GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not
 *   long enough, and in that case the @buf_size will be updated
 *   with the required size. %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE if
 *   the DN does not exist, or another error value on error. On success 0 is returned.
 **/
int gnutls_x509_crt_get_dn(gnutls_x509_crt_t cert, char *buf, size_t *buf_size)
{
  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  return _gnutls_x509_parse_dn(cert->cert,
             "tbsCertificate.subject.rdnSequence", buf,
             buf_size, GNUTLS_X509_DN_FLAG_COMPAT);
}

/**
 * gnutls_x509_crt_get_dn2:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @dn: a pointer to a structure to hold the name; must be freed using gnutls_free()
 *
 * This function will allocate buffer and copy the name of the Certificate.
 * The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
 * described in RFC4514. The output string will be ASCII or UTF-8
 * encoded, depending on the certificate data.
 *
 * This function does not output a fully RFC4514 compliant string, if
 * that is required see gnutls_x509_crt_get_dn3().
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 *
 * Since: 3.1.10
 **/
int gnutls_x509_crt_get_dn2(gnutls_x509_crt_t cert, gnutls_datum_t *dn)
{
  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  return _gnutls_x509_get_dn(cert->cert,
           "tbsCertificate.subject.rdnSequence", dn,
           GNUTLS_X509_DN_FLAG_COMPAT);
}

/**
 * gnutls_x509_crt_get_dn3:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @dn: a pointer to a structure to hold the name; must be freed using gnutls_free()
 * @flags: zero or %GNUTLS_X509_DN_FLAG_COMPAT
 *
 * This function will allocate buffer and copy the name of the Certificate.
 * The name will be in the form "C=xxxx,O=yyyy,CN=zzzz" as
 * described in RFC4514. The output string will be ASCII or UTF-8
 * encoded, depending on the certificate data.
 *
 * When the flag %GNUTLS_X509_DN_FLAG_COMPAT is specified, the output
 * format will match the format output by previous to 3.5.6 versions of GnuTLS
 * which was not not fully RFC4514-compliant.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 *
 * Since: 3.5.7
 **/
int gnutls_x509_crt_get_dn3(gnutls_x509_crt_t cert, gnutls_datum_t *dn,
          unsigned flags)
{
  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  return _gnutls_x509_get_dn(
    cert->cert, "tbsCertificate.subject.rdnSequence", dn, flags);
}

/**
 * gnutls_x509_crt_get_dn_by_oid:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @oid: holds an Object Identified in null terminated string
 * @indx: In case multiple same OIDs exist in the RDN, this specifies which to send. Use (0) to get the first one.
 * @raw_flag: If non-zero returns the raw DER data of the DN part.
 * @buf: a pointer where the DN part will be copied (may be null).
 * @buf_size: initially holds the size of @buf
 *
 * This function will extract the part of the name of the Certificate
 * subject specified by the given OID. The output, if the raw flag is
 * not used, will be encoded as described in RFC4514. Thus a string
 * that is ASCII or UTF-8 encoded, depending on the certificate data.
 *
 * Some helper macros with popular OIDs can be found in gnutls/x509.h
 * If raw flag is (0), this function will only return known OIDs as
 * text. Other OIDs will be DER encoded, as described in RFC4514 --
 * in hex format with a '#' prefix.  You can check about known OIDs
 * using gnutls_x509_dn_oid_known().
 *
 * If @buf is null then only the size will be filled. If the @raw_flag
 * is not specified the output is always null terminated, although the
 * @buf_size will not include the null character.
 *
 * Returns: %GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not
 *   long enough, and in that case the @buf_size will be updated with
 *   the required size. %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE if there
 *   are no data in the current index. On success 0 is returned.
 **/
int gnutls_x509_crt_get_dn_by_oid(gnutls_x509_crt_t cert, const char *oid,
          unsigned indx, unsigned int raw_flag,
          void *buf, size_t *buf_size)
{
  gnutls_datum_t td;
  int ret;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  ret = _gnutls_x509_parse_dn_oid(cert->cert,
          "tbsCertificate.subject.rdnSequence",
          oid, indx, raw_flag, &td);
  if (ret < 0)
    return gnutls_assert_val(ret);

  return _gnutls_strdatum_to_buf(&td, buf, buf_size);
}

/**
 * gnutls_x509_crt_get_dn_oid:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @indx: This specifies which OID to return. Use (0) to get the first one.
 * @oid: a pointer to a buffer to hold the OID (may be null)
 * @oid_size: initially holds the size of @oid
 *
 * This function will extract the OIDs of the name of the Certificate
 * subject specified by the given index.
 *
 * If @oid is null then only the size will be filled. The @oid
 * returned will be null terminated, although @oid_size will not
 * account for the trailing null.
 *
 * Returns: %GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is not
 *   long enough, and in that case the @buf_size will be updated with
 *   the required size. %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE if there
 *   are no data in the current index. On success 0 is returned.
 **/
int gnutls_x509_crt_get_dn_oid(gnutls_x509_crt_t cert, unsigned indx, void *oid,
             size_t *oid_size)
{
  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  return _gnutls_x509_get_dn_oid(cert->cert,
               "tbsCertificate.subject.rdnSequence",
               indx, oid, oid_size);
}

/**
 * gnutls_x509_crt_get_signature_algorithm:
 * @cert: should contain a #gnutls_x509_crt_t type
 *
 * This function will return a value of the #gnutls_sign_algorithm_t
 * enumeration that is the signature algorithm that has been used to
 * sign this certificate.
 *
 * Since 3.6.0 this function never returns a negative error code.
 * Error cases and unknown/unsupported signature algorithms are
 * mapped to %GNUTLS_SIGN_UNKNOWN.
 *
 * Returns: a #gnutls_sign_algorithm_t value
 **/
int gnutls_x509_crt_get_signature_algorithm(gnutls_x509_crt_t cert)
{
  return map_errs_to_zero(_gnutls_x509_get_signature_algorithm(
    cert->cert, "signatureAlgorithm"));
}

/**
 * gnutls_x509_crt_get_signature_oid:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @oid: a pointer to a buffer to hold the OID (may be null)
 * @oid_size: initially holds the size of @oid
 *
 * This function will return the OID of the signature algorithm
 * that has been used to sign this certificate. This is function
 * is useful in the case gnutls_x509_crt_get_signature_algorithm()
 * returned %GNUTLS_SIGN_UNKNOWN.
 *
 * Returns: zero or a negative error code on error.
 *
 * Since: 3.5.0
 **/
int gnutls_x509_crt_get_signature_oid(gnutls_x509_crt_t cert, char *oid,
              size_t *oid_size)
{
  char str[MAX_OID_SIZE];
  int len, result, ret;
  gnutls_datum_t out;

  len = sizeof(str);
  result = asn1_read_value(cert->cert, "signatureAlgorithm.algorithm",
         str, &len);
  if (result != ASN1_SUCCESS) {
    gnutls_assert();
    return _gnutls_asn2err(result);
  }

  out.data = (void *)str;
  out.size = len;

  ret = _gnutls_copy_string(&out, (void *)oid, oid_size);
  if (ret < 0) {
    gnutls_assert();
    return ret;
  }

  return 0;
}

/**
 * gnutls_x509_crt_get_pk_oid:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @oid: a pointer to a buffer to hold the OID (may be null)
 * @oid_size: initially holds the size of @oid
 *
 * This function will return the OID of the public key algorithm
 * on that certificate. This is function
 * is useful in the case gnutls_x509_crt_get_pk_algorithm()
 * returned %GNUTLS_PK_UNKNOWN.
 *
 * Returns: zero or a negative error code on error.
 *
 * Since: 3.5.0
 **/
int gnutls_x509_crt_get_pk_oid(gnutls_x509_crt_t cert, char *oid,
             size_t *oid_size)
{
  char str[MAX_OID_SIZE];
  int len, result, ret;
  gnutls_datum_t out;

  len = sizeof(str);
  result = asn1_read_value(
    cert->cert,
    "tbsCertificate.subjectPublicKeyInfo.algorithm.algorithm", str,
    &len);
  if (result != ASN1_SUCCESS) {
    gnutls_assert();
    return _gnutls_asn2err(result);
  }

  out.data = (void *)str;
  out.size = len;

  ret = _gnutls_copy_string(&out, (void *)oid, oid_size);
  if (ret < 0) {
    gnutls_assert();
    return ret;
  }

  return 0;
}

/**
 * gnutls_x509_crt_get_signature:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @sig: a pointer where the signature part will be copied (may be null).
 * @sig_size: initially holds the size of @sig
 *
 * This function will extract the signature field of a certificate.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int gnutls_x509_crt_get_signature(gnutls_x509_crt_t cert, char *sig,
          size_t *sig_size)
{
  gnutls_datum_t dsig = { NULL, 0 };
  int ret;

  if (cert == NULL)
    return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

  ret = _gnutls_x509_get_signature(cert->cert, "signature", &dsig);
  if (ret < 0)
    return gnutls_assert_val(ret);

  ret = _gnutls_copy_data(&dsig, (uint8_t *)sig, sig_size);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = 0;
cleanup:
  gnutls_free(dsig.data);
  return ret;
}

/**
 * gnutls_x509_crt_get_version:
 * @cert: should contain a #gnutls_x509_crt_t type
 *
 * This function will return the version of the specified Certificate.
 *
 * Returns: version of certificate, or a negative error code on error.
 **/
int gnutls_x509_crt_get_version(gnutls_x509_crt_t cert)
{
  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  return _gnutls_x509_get_version(cert->cert, "tbsCertificate.version");
}

/**
 * gnutls_x509_crt_get_activation_time:
 * @cert: should contain a #gnutls_x509_crt_t type
 *
 * This function will return the time this Certificate was or will be
 * activated.
 *
 * Returns: activation time, or (time_t)-1 on error.
 **/
time_t gnutls_x509_crt_get_activation_time(gnutls_x509_crt_t cert)
{
  if (cert == NULL) {
    gnutls_assert();
    return (time_t)-1;
  }

  return _gnutls_x509_get_time(cert->cert,
             "tbsCertificate.validity.notBefore", 0);
}

/**
 * gnutls_x509_crt_get_expiration_time:
 * @cert: should contain a #gnutls_x509_crt_t type
 *
 * This function will return the time this certificate was or will be
 * expired.
 *
 * Returns: expiration time, or (time_t)-1 on error.
 **/
time_t gnutls_x509_crt_get_expiration_time(gnutls_x509_crt_t cert)
{
  if (cert == NULL) {
    gnutls_assert();
    return (time_t)-1;
  }

  return _gnutls_x509_get_time(cert->cert,
             "tbsCertificate.validity.notAfter", 0);
}

/**
 * gnutls_x509_crt_get_private_key_usage_period:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @activation: The activation time
 * @expiration: The expiration time
 * @critical: the extension status
 *
 * This function will return the expiration and activation
 * times of the private key of the certificate. It relies on
 * the PKIX extension 2.5.29.16 being present.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
 * if the extension is not present, otherwise a negative error value.
 **/
int gnutls_x509_crt_get_private_key_usage_period(gnutls_x509_crt_t cert,
             time_t *activation,
             time_t *expiration,
             unsigned int *critical)
{
  int ret;
  gnutls_datum_t der = { NULL, 0 };

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  ret = _gnutls_x509_crt_get_extension(cert, "2.5.29.16", 0, &der,
               critical);
  if (ret < 0)
    return gnutls_assert_val(ret);

  if (der.size == 0 || der.data == NULL)
    return gnutls_assert_val(GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);

  ret = gnutls_x509_ext_import_private_key_usage_period(&der, activation,
                    expiration);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = 0;

cleanup:
  _gnutls_free_datum(&der);

  return ret;
}

/**
 * gnutls_x509_crt_get_serial:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @result: The place where the serial number will be copied
 * @result_size: Holds the size of the result field.
 *
 * This function will return the X.509 certificate's serial number.
 * This is obtained by the X509 Certificate serialNumber field. Serial
 * is not always a 32 or 64bit number. Some CAs use large serial
 * numbers, thus it may be wise to handle it as something uint8_t.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int gnutls_x509_crt_get_serial(gnutls_x509_crt_t cert, void *result,
             size_t *result_size)
{
  int ret, len;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  len = *result_size;
  ret = asn1_read_value(cert->cert, "tbsCertificate.serialNumber", result,
            &len);
  *result_size = len;

  if (ret != ASN1_SUCCESS) {
    gnutls_assert();
    return _gnutls_asn2err(ret);
  }

  return 0;
}

/**
 * gnutls_x509_crt_get_subject_key_id:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @ret: The place where the identifier will be copied
 * @ret_size: Holds the size of the result field.
 * @critical: will be non-zero if the extension is marked as critical (may be null)
 *
 * This function will return the X.509v3 certificate's subject key
 * identifier.  This is obtained by the X.509 Subject Key identifier
 * extension field (2.5.29.14).
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
 * if the extension is not present, otherwise a negative error value.
 **/
int gnutls_x509_crt_get_subject_key_id(gnutls_x509_crt_t cert, void *ret,
               size_t *ret_size, unsigned int *critical)
{
  int result;
  gnutls_datum_t id = { NULL, 0 };
  gnutls_datum_t der = { NULL, 0 };

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  if (ret == NULL)
    *ret_size = 0;

  if ((result = _gnutls_x509_crt_get_extension(cert, "2.5.29.14", 0, &der,
                 critical)) < 0) {
    return result;
  }

  result = gnutls_x509_ext_import_subject_key_id(&der, &id);
  if (result < 0) {
    gnutls_assert();
    goto cleanup;
  }

  result = _gnutls_copy_data(&id, ret, ret_size);
  if (result < 0) {
    gnutls_assert();
    goto cleanup;
  }

  result = 0;

cleanup:
  gnutls_free(der.data);
  gnutls_free(id.data);
  return result;
}

inline static int is_type_printable(int type)
{
  if (type == GNUTLS_SAN_DNSNAME || type == GNUTLS_SAN_RFC822NAME ||
      type == GNUTLS_SAN_URI || type == GNUTLS_SAN_OTHERNAME_XMPP ||
      type == GNUTLS_SAN_OTHERNAME || type == GNUTLS_SAN_REGISTERED_ID)
    return 1;
  else
    return 0;
}

/**
 * gnutls_x509_crt_get_authority_key_gn_serial:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
 * @alt: is the place where the alternative name will be copied to
 * @alt_size: holds the size of alt.
 * @alt_type: holds the type of the alternative name (one of gnutls_x509_subject_alt_name_t).
 * @serial: buffer to store the serial number (may be null)
 * @serial_size: Holds the size of the serial field (may be null)
 * @critical: will be non-zero if the extension is marked as critical (may be null)
 *
 * This function will return the X.509 authority key
 * identifier when stored as a general name (authorityCertIssuer)
 * and serial number.
 *
 * Because more than one general names might be stored
 * @seq can be used as a counter to request them all until
 * %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
 * if the extension is not present, otherwise a negative error value.
 *
 * Since: 3.0
 **/
int gnutls_x509_crt_get_authority_key_gn_serial(
  gnutls_x509_crt_t cert, unsigned int seq, void *alt, size_t *alt_size,
  unsigned int *alt_type, void *serial, size_t *serial_size,
  unsigned int *critical)
{
  int ret;
  gnutls_datum_t der, san, iserial;
  gnutls_x509_aki_t aki = NULL;
  unsigned san_type;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  if ((ret = _gnutls_x509_crt_get_extension(cert, "2.5.29.35", 0, &der,
              critical)) < 0) {
    return gnutls_assert_val(ret);
  }

  if (der.size == 0 || der.data == NULL) {
    gnutls_assert();
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
  }

  ret = gnutls_x509_aki_init(&aki);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = gnutls_x509_ext_import_authority_key_id(&der, aki, 0);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = gnutls_x509_aki_get_cert_issuer(aki, seq, &san_type, &san, NULL,
                &iserial);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  if (is_type_printable(san_type))
    ret = _gnutls_copy_string(&san, alt, alt_size);
  else
    ret = _gnutls_copy_data(&san, alt, alt_size);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  if (alt_type)
    *alt_type = san_type;

  ret = _gnutls_copy_data(&iserial, serial, serial_size);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = 0;
cleanup:
  if (aki != NULL)
    gnutls_x509_aki_deinit(aki);
  gnutls_free(der.data);
  return ret;
}

/**
 * gnutls_x509_crt_get_authority_key_id:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @id: The place where the identifier will be copied
 * @id_size: Holds the size of the id field.
 * @critical: will be non-zero if the extension is marked as critical (may be null)
 *
 * This function will return the X.509v3 certificate authority's key
 * identifier.  This is obtained by the X.509 Authority Key
 * identifier extension field (2.5.29.35). Note that this function
 * only returns the keyIdentifier field of the extension and
 * %GNUTLS_E_X509_UNSUPPORTED_EXTENSION, if the extension contains
 * the name and serial number of the certificate. In that case
 * gnutls_x509_crt_get_authority_key_gn_serial() may be used.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
 * if the extension is not present, otherwise a negative error value.
 **/
int gnutls_x509_crt_get_authority_key_id(gnutls_x509_crt_t cert, void *id,
           size_t *id_size,
           unsigned int *critical)
{
  int ret;
  gnutls_datum_t der, l_id;
  gnutls_x509_aki_t aki = NULL;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  if ((ret = _gnutls_x509_crt_get_extension(cert, "2.5.29.35", 0, &der,
              critical)) < 0) {
    return gnutls_assert_val(ret);
  }

  if (der.size == 0 || der.data == NULL) {
    gnutls_assert();
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
  }

  ret = gnutls_x509_aki_init(&aki);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = gnutls_x509_ext_import_authority_key_id(&der, aki, 0);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = gnutls_x509_aki_get_id(aki, &l_id);

  if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) {
    gnutls_datum_t serial;
    ret = gnutls_x509_aki_get_cert_issuer(aki, 0, NULL, NULL, NULL,
                  &serial);
    if (ret >= 0) {
      ret = gnutls_assert_val(
        GNUTLS_E_X509_UNSUPPORTED_EXTENSION);
    } else {
      ret = gnutls_assert_val(
        GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);
    }
  }

  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = _gnutls_copy_data(&l_id, id, id_size);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = 0;
cleanup:
  if (aki != NULL)
    gnutls_x509_aki_deinit(aki);
  gnutls_free(der.data);
  return ret;
}

/**
 * gnutls_x509_crt_get_pk_algorithm:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @bits: if bits is non null it will hold the size of the parameters' in bits
 *
 * This function will return the public key algorithm of an X.509
 * certificate.
 *
 * If bits is non null, it should have enough size to hold the parameters
 * size in bits. For RSA the bits returned is the modulus.
 * For DSA the bits returned are of the public
 * exponent.
 *
 * Unknown/unsupported algorithms are mapped to %GNUTLS_PK_UNKNOWN.
 *
 * Returns: a member of the #gnutls_pk_algorithm_t enumeration on
 * success, or a negative error code on error.
 **/
int gnutls_x509_crt_get_pk_algorithm(gnutls_x509_crt_t cert, unsigned int *bits)
{
  int result;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  if (bits)
    *bits = 0;

  result = _gnutls_x509_get_pk_algorithm(
    cert->cert, "tbsCertificate.subjectPublicKeyInfo", NULL, bits);

  if (result < 0) {
    gnutls_assert();
    return result;
  }

  return result;
}

/**
 * gnutls_x509_crt_get_spki:
 * @cert: a certificate of type #gnutls_x509_crt_t
 * @spki: a SubjectPublicKeyInfo structure of type #gnutls_x509_spki_t
 * @flags: must be zero
 *
 * This function will return the public key information of an X.509
 * certificate. The provided @spki must be initialized.
 *
 * Since: 3.6.0
 **/
int gnutls_x509_crt_get_spki(gnutls_x509_crt_t cert, gnutls_x509_spki_t spki,
           unsigned int flags)
{
  int result;
  gnutls_x509_spki_st params;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  spki->pk = gnutls_x509_crt_get_pk_algorithm(cert, NULL);

  memset(&params, 0, sizeof(params));

  result = _gnutls_x509_crt_read_spki_params(cert, &params);
  if (result < 0) {
    gnutls_assert();
    return result;
  }

  if (params.pk == GNUTLS_PK_UNKNOWN)
    return gnutls_assert_val(GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);

  spki->rsa_pss_dig = params.rsa_pss_dig;
  spki->salt_size = params.salt_size;

  return 0;
}

/* returns the type and the name on success.
 * Type is also returned as a parameter in case of an error.
 *
 * @seq: in case of GeneralNames it will return the corresponding name.
 *       in case of GeneralName, it must be -1
 * @dname: the name returned
 * @ret_type: The type of the name
 * @othername_oid: if the name is otherName return the OID
 *
 */
int _gnutls_parse_general_name2(asn1_node src, const char *src_name, int seq,
        gnutls_datum_t *dname, unsigned int *ret_type,
        int othername_oid)
{
  int len, ret;
  char nptr[MAX_NAME_SIZE];
  int result;
  gnutls_datum_t tmp = { NULL, 0 };
  char choice_type[128];
  gnutls_x509_subject_alt_name_t type;

  if (seq != -1) {
    seq++; /* 0->1, 1->2 etc */

    if (src_name[0] != 0)
      snprintf(nptr, sizeof(nptr), "%s.?%d", src_name, seq);
    else
      snprintf(nptr, sizeof(nptr), "?%d", seq);
  } else {
    snprintf(nptr, sizeof(nptr), "%s", src_name);
  }

  len = sizeof(choice_type);
  result = asn1_read_value(src, nptr, choice_type, &len);
  if (result == ASN1_VALUE_NOT_FOUND ||
      result == ASN1_ELEMENT_NOT_FOUND) {
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
  }

  if (result != ASN1_SUCCESS) {
    gnutls_assert();
    return _gnutls_asn2err(result);
  }

  type = _gnutls_x509_san_find_type(choice_type);
  if (type == (gnutls_x509_subject_alt_name_t)-1) {
    gnutls_assert();
    return GNUTLS_E_X509_UNKNOWN_SAN;
  }

  if (ret_type)
    *ret_type = type;

  if (type == GNUTLS_SAN_OTHERNAME) {
    if (othername_oid)
      _gnutls_str_cat(nptr, sizeof(nptr),
          ".otherName.type-id");
    else
      _gnutls_str_cat(nptr, sizeof(nptr), ".otherName.value");

    ret = _gnutls_x509_read_value(src, nptr, &tmp);
    if (ret < 0) {
      gnutls_assert();
      return ret;
    }

    if (othername_oid) {
      dname->size = tmp.size;
      dname->data = tmp.data;
    } else {
      char oid[MAX_OID_SIZE];

      if (src_name[0] != 0 && seq != -1)
        snprintf(nptr, sizeof(nptr),
           "%s.?%d.otherName.type-id", src_name,
           seq);
      else if (src_name[0] != 0)
        snprintf(nptr, sizeof(nptr),
           "%s.otherName.type-id", src_name);
      else
        snprintf(nptr, sizeof(nptr),
           "?%d.otherName.type-id", seq);

      len = sizeof(oid);

      result = asn1_read_value(src, nptr, oid, &len);
      if (result != ASN1_SUCCESS) {
        gnutls_assert();
        ret = _gnutls_asn2err(result);
        goto cleanup;
      }
      if (len > 0)
        len--;

      dname->size = tmp.size;
      dname->data = tmp.data;
    }
  } else if (type == GNUTLS_SAN_DN) {
    _gnutls_str_cat(nptr, sizeof(nptr), ".directoryName");
    ret = _gnutls_x509_get_dn(src, nptr, dname, 0);
    if (ret < 0) {
      gnutls_assert();
      goto cleanup;
    }
  } else if (othername_oid) {
    gnutls_assert();
    ret = GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
    goto cleanup;
  } else {
    _gnutls_str_cat(nptr, sizeof(nptr), ".");
    _gnutls_str_cat(nptr, sizeof(nptr), choice_type);

    ret = _gnutls_x509_read_null_value(src, nptr, &tmp);
    if (ret < 0) {
      gnutls_assert();
      return ret;
    }

    /* _gnutls_x509_read_value() null terminates */
    dname->size = tmp.size;
    dname->data = tmp.data;
  }

  return type;

cleanup:
  gnutls_free(tmp.data);
  return ret;
}

/* returns the type and the name on success.
 * Type is also returned as a parameter in case of an error.
 */
int _gnutls_parse_general_name(asn1_node src, const char *src_name, int seq,
             void *name, size_t *name_size,
             unsigned int *ret_type, int othername_oid)
{
  int ret;
  gnutls_datum_t res = { NULL, 0 };
  unsigned type;

  ret = _gnutls_parse_general_name2(src, src_name, seq, &res, ret_type,
            othername_oid);
  if (ret < 0)
    return gnutls_assert_val(ret);

  type = ret;

  if (is_type_printable(type)) {
    ret = _gnutls_copy_string(&res, name, name_size);
  } else {
    ret = _gnutls_copy_data(&res, name, name_size);
  }

  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = type;
cleanup:
  gnutls_free(res.data);
  return ret;
}

static int get_alt_name(gnutls_subject_alt_names_t san, unsigned int seq,
      uint8_t *alt, size_t *alt_size, unsigned int *alt_type,
      unsigned int *critical, int othername_oid)
{
  int ret;
  gnutls_datum_t ooid = { NULL, 0 };
  gnutls_datum_t oname;
  gnutls_datum_t virt = { NULL, 0 };
  unsigned int type;

  if (san == NULL) {
    gnutls_assert();
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
  }

  if (alt == NULL)
    *alt_size = 0;

  ret = gnutls_subject_alt_names_get(san, seq, &type, &oname, &ooid);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  if (type == GNUTLS_SAN_OTHERNAME && ooid.data) {
    unsigned vtype;
    ret = gnutls_x509_othername_to_virtual((char *)ooid.data,
                   &oname, &vtype, &virt);
    if (ret >= 0) {
      type = vtype;
      oname.data = virt.data;
      oname.size = virt.size;
    }
  }

  if (alt_type)
    *alt_type = type;

  if (othername_oid) {
    ret = _gnutls_copy_string(&ooid, alt, alt_size);
  } else {
    if (is_type_printable(type)) {
      ret = _gnutls_copy_string(&oname, alt, alt_size);
    } else {
      ret = _gnutls_copy_data(&oname, alt, alt_size);
    }
  }

  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = type;
cleanup:
  gnutls_free(virt.data);

  return ret;
}

/**
 * gnutls_x509_crt_get_subject_alt_name:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
 * @san: is the place where the alternative name will be copied to
 * @san_size: holds the size of san.
 * @critical: will be non-zero if the extension is marked as critical (may be null)
 *
 * This function retrieves the Alternative Name (2.5.29.17), contained
 * in the given certificate in the X509v3 Certificate Extensions.
 *
 * When the SAN type is otherName, it will extract the data in the
 * otherName's value field, and %GNUTLS_SAN_OTHERNAME is returned.
 * You may use gnutls_x509_crt_get_subject_alt_othername_oid() to get
 * the corresponding OID and the "virtual" SAN types (e.g.,
 * %GNUTLS_SAN_OTHERNAME_XMPP).
 *
 * If an otherName OID is known, the data will be decoded.  Otherwise
 * the returned data will be DER encoded, and you will have to decode
 * it yourself.  Currently, only the RFC 3920 id-on-xmppAddr SAN is
 * recognized.
 *
 * Returns: the alternative subject name type on success, one of the
 *   enumerated #gnutls_x509_subject_alt_name_t.  It will return
 *   %GNUTLS_E_SHORT_MEMORY_BUFFER if @san_size is not large enough to
 *   hold the value.  In that case @san_size will be updated with the
 *   required size.  If the certificate does not have an Alternative
 *   name with the specified sequence number then
 *   %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.
 **/
int gnutls_x509_crt_get_subject_alt_name(gnutls_x509_crt_t cert,
           unsigned int seq, void *san,
           size_t *san_size,
           unsigned int *critical)
{
  return get_alt_name(cert->san, seq, san, san_size, NULL, critical, 0);
}

/**
 * gnutls_x509_crt_get_issuer_alt_name:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
 * @ian: is the place where the alternative name will be copied to
 * @ian_size: holds the size of ian.
 * @critical: will be non-zero if the extension is marked as critical (may be null)
 *
 * This function retrieves the Issuer Alternative Name (2.5.29.18),
 * contained in the given certificate in the X509v3 Certificate
 * Extensions.
 *
 * When the SAN type is otherName, it will extract the data in the
 * otherName's value field, and %GNUTLS_SAN_OTHERNAME is returned.
 * You may use gnutls_x509_crt_get_subject_alt_othername_oid() to get
 * the corresponding OID and the "virtual" SAN types (e.g.,
 * %GNUTLS_SAN_OTHERNAME_XMPP).
 *
 * If an otherName OID is known, the data will be decoded.  Otherwise
 * the returned data will be DER encoded, and you will have to decode
 * it yourself.  Currently, only the RFC 3920 id-on-xmppAddr Issuer
 * AltName is recognized.
 *
 * Returns: the alternative issuer name type on success, one of the
 *   enumerated #gnutls_x509_subject_alt_name_t.  It will return
 *   %GNUTLS_E_SHORT_MEMORY_BUFFER if @ian_size is not large enough
 *   to hold the value.  In that case @ian_size will be updated with
 *   the required size.  If the certificate does not have an
 *   Alternative name with the specified sequence number then
 *   %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.
 *
 * Since: 2.10.0
 **/
int gnutls_x509_crt_get_issuer_alt_name(gnutls_x509_crt_t cert,
          unsigned int seq, void *ian,
          size_t *ian_size,
          unsigned int *critical)
{
  return get_alt_name(cert->ian, seq, ian, ian_size, NULL, critical, 0);
}

/**
 * gnutls_x509_crt_get_subject_alt_name2:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
 * @san: is the place where the alternative name will be copied to
 * @san_size: holds the size of ret.
 * @san_type: holds the type of the alternative name (one of gnutls_x509_subject_alt_name_t).
 * @critical: will be non-zero if the extension is marked as critical (may be null)
 *
 * This function will return the alternative names, contained in the
 * given certificate. It is the same as
 * gnutls_x509_crt_get_subject_alt_name() except for the fact that it
 * will return the type of the alternative name in @san_type even if
 * the function fails for some reason (i.e.  the buffer provided is
 * not enough).
 *
 * Returns: the alternative subject name type on success, one of the
 *   enumerated #gnutls_x509_subject_alt_name_t.  It will return
 *   %GNUTLS_E_SHORT_MEMORY_BUFFER if @san_size is not large enough
 *   to hold the value.  In that case @san_size will be updated with
 *   the required size.  If the certificate does not have an
 *   Alternative name with the specified sequence number then
 *   %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.
 **/
int gnutls_x509_crt_get_subject_alt_name2(gnutls_x509_crt_t cert,
            unsigned int seq, void *san,
            size_t *san_size,
            unsigned int *san_type,
            unsigned int *critical)
{
  return get_alt_name(cert->san, seq, san, san_size, san_type, critical,
          0);
}

/**
 * gnutls_x509_crt_get_issuer_alt_name2:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
 * @ian: is the place where the alternative name will be copied to
 * @ian_size: holds the size of ret.
 * @ian_type: holds the type of the alternative name (one of gnutls_x509_subject_alt_name_t).
 * @critical: will be non-zero if the extension is marked as critical (may be null)
 *
 * This function will return the alternative names, contained in the
 * given certificate. It is the same as
 * gnutls_x509_crt_get_issuer_alt_name() except for the fact that it
 * will return the type of the alternative name in @ian_type even if
 * the function fails for some reason (i.e.  the buffer provided is
 * not enough).
 *
 * Returns: the alternative issuer name type on success, one of the
 *   enumerated #gnutls_x509_subject_alt_name_t.  It will return
 *   %GNUTLS_E_SHORT_MEMORY_BUFFER if @ian_size is not large enough
 *   to hold the value.  In that case @ian_size will be updated with
 *   the required size.  If the certificate does not have an
 *   Alternative name with the specified sequence number then
 *   %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.
 *
 * Since: 2.10.0
 *
 **/
int gnutls_x509_crt_get_issuer_alt_name2(gnutls_x509_crt_t cert,
           unsigned int seq, void *ian,
           size_t *ian_size,
           unsigned int *ian_type,
           unsigned int *critical)
{
  return get_alt_name(cert->ian, seq, ian, ian_size, ian_type, critical,
          0);
}

/**
 * gnutls_x509_crt_get_subject_alt_othername_oid:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
 * @oid: is the place where the otherName OID will be copied to
 * @oid_size: holds the size of ret.
 *
 * This function will extract the type OID of an otherName Subject
 * Alternative Name, contained in the given certificate, and return
 * the type as an enumerated element.
 *
 * This function is only useful if
 * gnutls_x509_crt_get_subject_alt_name() returned
 * %GNUTLS_SAN_OTHERNAME.
 *
 * If @oid is null then only the size will be filled. The @oid
 * returned will be null terminated, although @oid_size will not
 * account for the trailing null.
 *
 * Returns: the alternative subject name type on success, one of the
 * enumerated gnutls_x509_subject_alt_name_t.  For supported OIDs, it
 * will return one of the virtual (GNUTLS_SAN_OTHERNAME_*) types,
 * e.g. %GNUTLS_SAN_OTHERNAME_XMPP, and %GNUTLS_SAN_OTHERNAME for
 * unknown OIDs.  It will return %GNUTLS_E_SHORT_MEMORY_BUFFER if
 * @ian_size is not large enough to hold the value.  In that case
 * @ian_size will be updated with the required size.  If the
 * certificate does not have an Alternative name with the specified
 * sequence number and with the otherName type then
 * %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.
 **/
int gnutls_x509_crt_get_subject_alt_othername_oid(gnutls_x509_crt_t cert,
              unsigned int seq, void *oid,
              size_t *oid_size)
{
  return get_alt_name(cert->san, seq, oid, oid_size, NULL, NULL, 1);
}

/**
 * gnutls_x509_crt_get_issuer_alt_othername_oid:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @seq: specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.)
 * @ret: is the place where the otherName OID will be copied to
 * @ret_size: holds the size of ret.
 *
 * This function will extract the type OID of an otherName Subject
 * Alternative Name, contained in the given certificate, and return
 * the type as an enumerated element.
 *
 * If @oid is null then only the size will be filled. The @oid
 * returned will be null terminated, although @oid_size will not
 * account for the trailing null.
 *
 * This function is only useful if
 * gnutls_x509_crt_get_issuer_alt_name() returned
 * %GNUTLS_SAN_OTHERNAME.
 *
 * Returns: the alternative issuer name type on success, one of the
 * enumerated gnutls_x509_subject_alt_name_t.  For supported OIDs, it
 * will return one of the virtual (GNUTLS_SAN_OTHERNAME_*) types,
 * e.g. %GNUTLS_SAN_OTHERNAME_XMPP, and %GNUTLS_SAN_OTHERNAME for
 * unknown OIDs.  It will return %GNUTLS_E_SHORT_MEMORY_BUFFER if
 * @ret_size is not large enough to hold the value.  In that case
 * @ret_size will be updated with the required size.  If the
 * certificate does not have an Alternative name with the specified
 * sequence number and with the otherName type then
 * %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.
 *
 * Since: 2.10.0
 **/
int gnutls_x509_crt_get_issuer_alt_othername_oid(gnutls_x509_crt_t cert,
             unsigned int seq, void *ret,
             size_t *ret_size)
{
  return get_alt_name(cert->ian, seq, ret, ret_size, NULL, NULL, 1);
}

/**
 * gnutls_x509_crt_get_basic_constraints:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @critical: will be non-zero if the extension is marked as critical
 * @ca: pointer to output integer indicating CA status, may be NULL,
 *   value is 1 if the certificate CA flag is set, 0 otherwise.
 * @pathlen: pointer to output integer indicating path length (may be
 *   NULL), non-negative error codes indicate a present pathLenConstraint
 *   field and the actual value, -1 indicate that the field is absent.
 *
 * This function will read the certificate's basic constraints, and
 * return the certificates CA status.  It reads the basicConstraints
 * X.509 extension (2.5.29.19).
 *
 * Returns: If the certificate is a CA a positive value will be
 * returned, or (0) if the certificate does not have CA flag set.  A
 * negative error code may be returned in case of errors.  If the
 * certificate does not contain the basicConstraints extension
 * GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.
 **/
int gnutls_x509_crt_get_basic_constraints(gnutls_x509_crt_t cert,
            unsigned int *critical,
            unsigned int *ca, int *pathlen)
{
  int result;
  gnutls_datum_t basicConstraints;
  unsigned int tmp_ca;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  if ((result = _gnutls_x509_crt_get_extension(
         cert, "2.5.29.19", 0, &basicConstraints, critical)) < 0) {
    return result;
  }

  if (basicConstraints.size == 0 || basicConstraints.data == NULL) {
    gnutls_assert();
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
  }

  result = gnutls_x509_ext_import_basic_constraints(&basicConstraints,
                &tmp_ca, pathlen);
  if (ca)
    *ca = tmp_ca;

  _gnutls_free_datum(&basicConstraints);

  if (result < 0) {
    gnutls_assert();
    return result;
  }

  return tmp_ca;
}

/**
 * gnutls_x509_crt_get_ca_status:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @critical: will be non-zero if the extension is marked as critical
 *
 * This function will return certificates CA status, by reading the
 * basicConstraints X.509 extension (2.5.29.19). If the certificate is
 * a CA a positive value will be returned, or (0) if the certificate
 * does not have CA flag set.
 *
 * Use gnutls_x509_crt_get_basic_constraints() if you want to read the
 * pathLenConstraint field too.
 *
 * Returns: If the certificate is a CA a positive value will be
 * returned, or (0) if the certificate does not have CA flag set.  A
 * negative error code may be returned in case of errors.  If the
 * certificate does not contain the basicConstraints extension
 * GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.
 **/
int gnutls_x509_crt_get_ca_status(gnutls_x509_crt_t cert,
          unsigned int *critical)
{
  int pathlen;
  unsigned int ca;
  return gnutls_x509_crt_get_basic_constraints(cert, critical, &ca,
                 &pathlen);
}

/**
 * gnutls_x509_crt_get_key_usage:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @key_usage: where the key usage bits will be stored
 * @critical: will be non-zero if the extension is marked as critical
 *
 * This function will return certificate's key usage, by reading the
 * keyUsage X.509 extension (2.5.29.15). The key usage value will ORed
 * values of the: %GNUTLS_KEY_DIGITAL_SIGNATURE,
 * %GNUTLS_KEY_NON_REPUDIATION, %GNUTLS_KEY_KEY_ENCIPHERMENT,
 * %GNUTLS_KEY_DATA_ENCIPHERMENT, %GNUTLS_KEY_KEY_AGREEMENT,
 * %GNUTLS_KEY_KEY_CERT_SIGN, %GNUTLS_KEY_CRL_SIGN,
 * %GNUTLS_KEY_ENCIPHER_ONLY, %GNUTLS_KEY_DECIPHER_ONLY.
 *
 * Returns: zero on success, or a negative error code in case of
 *   parsing error.  If the certificate does not contain the keyUsage
 *   extension %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be
 *   returned.
 **/
int gnutls_x509_crt_get_key_usage(gnutls_x509_crt_t cert,
          unsigned int *key_usage,
          unsigned int *critical)
{
  int result;
  gnutls_datum_t keyUsage;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  if ((result = _gnutls_x509_crt_get_extension(
         cert, "2.5.29.15", 0, &keyUsage, critical)) < 0) {
    return result;
  }

  if (keyUsage.size == 0 || keyUsage.data == NULL) {
    gnutls_assert();
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
  }

  result = gnutls_x509_ext_import_key_usage(&keyUsage, key_usage);
  _gnutls_free_datum(&keyUsage);

  if (result < 0) {
    gnutls_assert();
    return result;
  }

  return 0;
}

/**
 * gnutls_x509_crt_get_inhibit_anypolicy:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @skipcerts: will hold the number of certificates after which anypolicy is no longer acceptable.
 * @critical: will be non-zero if the extension is marked as critical
 *
 * This function will return certificate's value of the SkipCerts, i.e.,
 * the Inhibit anyPolicy X.509 extension (2.5.29.54).
 *
 * The returned value is the number of additional certificates that
 * may appear in the path before the anyPolicy is no longer acceptable.

 * Returns: zero on success, or a negative error code in case of
 *   parsing error.  If the certificate does not contain the Inhibit anyPolicy
 *   extension %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be
 *   returned.
 *
 * Since: 3.6.0
 **/
int gnutls_x509_crt_get_inhibit_anypolicy(gnutls_x509_crt_t cert,
            unsigned int *skipcerts,
            unsigned int *critical)
{
  int ret;
  gnutls_datum_t ext;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  if ((ret = _gnutls_x509_crt_get_extension(cert, "2.5.29.54", 0, &ext,
              critical)) < 0) {
    return ret;
  }

  if (ext.size == 0 || ext.data == NULL) {
    gnutls_assert();
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
  }

  ret = gnutls_x509_ext_import_key_usage(&ext, skipcerts);
  _gnutls_free_datum(&ext);

  if (ret < 0) {
    gnutls_assert();
    return ret;
  }

  return 0;
}

/**
 * gnutls_x509_crt_get_proxy:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @critical: will be non-zero if the extension is marked as critical
 * @pathlen: pointer to output integer indicating path length (may be
 *   NULL), non-negative error codes indicate a present pCPathLenConstraint
 *   field and the actual value, -1 indicate that the field is absent.
 * @policyLanguage: output variable with OID of policy language
 * @policy: output variable with policy data
 * @sizeof_policy: output variable size of policy data
 *
 * This function will get information from a proxy certificate.  It
 * reads the ProxyCertInfo X.509 extension (1.3.6.1.5.5.7.1.14).
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,
 *   otherwise a negative error code is returned.
 **/
int gnutls_x509_crt_get_proxy(gnutls_x509_crt_t cert, unsigned int *critical,
            int *pathlen, char **policyLanguage,
            char **policy, size_t *sizeof_policy)
{
  int result;
  gnutls_datum_t proxyCertInfo;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  if ((result = _gnutls_x509_crt_get_extension(cert, "1.3.6.1.5.5.7.1.14",
                 0, &proxyCertInfo,
                 critical)) < 0) {
    return result;
  }

  if (proxyCertInfo.size == 0 || proxyCertInfo.data == NULL) {
    gnutls_assert();
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
  }

  result = gnutls_x509_ext_import_proxy(
    &proxyCertInfo, pathlen, policyLanguage, policy, sizeof_policy);
  _gnutls_free_datum(&proxyCertInfo);
  if (result < 0) {
    gnutls_assert();
    return result;
  }

  return 0;
}

/**
 * gnutls_x509_policy_release:
 * @policy: a certificate policy
 *
 * This function will deinitialize all memory associated with the provided
 * @policy. The policy is allocated using gnutls_x509_crt_get_policy().
 *
 * Since: 3.1.5
 **/
void gnutls_x509_policy_release(struct gnutls_x509_policy_st *policy)
{
  unsigned i;

  gnutls_free(policy->oid);
  for (i = 0; i < policy->qualifiers; i++)
    gnutls_free(policy->qualifier[i].data);
}

/**
 * gnutls_x509_crt_get_policy:
 * @crt: should contain a #gnutls_x509_crt_t type
 * @indx: This specifies which policy to return. Use (0) to get the first one.
 * @policy: A pointer to a policy structure.
 * @critical: will be non-zero if the extension is marked as critical
 *
 * This function will extract the certificate policy (extension 2.5.29.32)
 * specified by the given index.
 *
 * The policy returned by this function must be deinitialized by using
 * gnutls_x509_policy_release().
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
 * if the extension is not present, otherwise a negative error value.
 *
 * Since: 3.1.5
 **/
int gnutls_x509_crt_get_policy(gnutls_x509_crt_t crt, unsigned indx,
             struct gnutls_x509_policy_st *policy,
             unsigned int *critical)
{
  gnutls_datum_t tmpd = { NULL, 0 };
  int ret;
  gnutls_x509_policies_t policies = NULL;

  if (crt == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  memset(policy, 0, sizeof(*policy));

  ret = gnutls_x509_policies_init(&policies);
  if (ret < 0)
    return gnutls_assert_val(ret);

  if ((ret = _gnutls_x509_crt_get_extension(crt, "2.5.29.32", 0, &tmpd,
              critical)) < 0) {
    goto cleanup;
  }

  if (tmpd.size == 0 || tmpd.data == NULL) {
    gnutls_assert();
    ret = GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
    goto cleanup;
  }

  ret = gnutls_x509_ext_import_policies(&tmpd, policies, 0);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = gnutls_x509_policies_get(policies, indx, policy);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  _gnutls_x509_policies_erase(policies, indx);

  ret = 0;

cleanup:
  if (policies != NULL)
    gnutls_x509_policies_deinit(policies);
  _gnutls_free_datum(&tmpd);

  return ret;
}

/**
 * gnutls_x509_crt_get_extension_by_oid:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @oid: holds an Object Identified in null terminated string
 * @indx: In case multiple same OIDs exist in the extensions, this specifies which to send. Use (0) to get the first one.
 * @buf: a pointer to a structure to hold the name (may be null)
 * @buf_size: initially holds the size of @buf
 * @critical: will be non-zero if the extension is marked as critical
 *
 * This function will return the extension specified by the OID in the
 * certificate.  The extensions will be returned as binary data DER
 * encoded, in the provided buffer.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,
 *   otherwise a negative error code is returned. If the certificate does not
 *   contain the specified extension
 *   GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.
 **/
int gnutls_x509_crt_get_extension_by_oid(gnutls_x509_crt_t cert,
           const char *oid, unsigned indx,
           void *buf, size_t *buf_size,
           unsigned int *critical)
{
  int result;
  gnutls_datum_t output;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  if ((result = _gnutls_x509_crt_get_extension(cert, oid, indx, &output,
                 critical)) < 0) {
    gnutls_assert();
    return result;
  }

  if (output.size == 0 || output.data == NULL) {
    gnutls_assert();
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
  }

  if (output.size > (unsigned int)*buf_size) {
    *buf_size = output.size;
    _gnutls_free_datum(&output);
    return GNUTLS_E_SHORT_MEMORY_BUFFER;
  }

  *buf_size = output.size;

  if (buf)
    memcpy(buf, output.data, output.size);

  _gnutls_free_datum(&output);

  return 0;
}

/**
 * gnutls_x509_crt_get_extension_by_oid2:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @oid: holds an Object Identified in null terminated string
 * @indx: In case multiple same OIDs exist in the extensions, this specifies which to send. Use (0) to get the first one.
 * @output: will hold the allocated extension data
 * @critical: will be non-zero if the extension is marked as critical
 *
 * This function will return the extension specified by the OID in the
 * certificate.  The extensions will be returned as binary data DER
 * encoded, in the provided buffer.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,
 *   otherwise a negative error code is returned. If the certificate does not
 *   contain the specified extension
 *   GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned.
 *
 * Since: 3.3.8
 **/
int gnutls_x509_crt_get_extension_by_oid2(gnutls_x509_crt_t cert,
            const char *oid, unsigned indx,
            gnutls_datum_t *output,
            unsigned int *critical)
{
  int ret;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  if ((ret = _gnutls_x509_crt_get_extension(cert, oid, indx, output,
              critical)) < 0) {
    gnutls_assert();
    return ret;
  }

  if (output->size == 0 || output->data == NULL) {
    gnutls_assert();
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
  }

  return 0;
}

/**
 * gnutls_x509_crt_get_extension_oid:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @indx: Specifies which extension OID to send. Use (0) to get the first one.
 * @oid: a pointer to a structure to hold the OID (may be null)
 * @oid_size: initially holds the size of @oid
 *
 * This function will return the requested extension OID in the certificate.
 * The extension OID will be stored as a string in the provided buffer.
 *
 * The @oid returned will be null terminated, although @oid_size will not
 * account for the trailing null.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,
 *   otherwise a negative error code is returned.  If you have reached the
 *   last extension available %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
 *   will be returned.
 **/
int gnutls_x509_crt_get_extension_oid(gnutls_x509_crt_t cert, unsigned indx,
              void *oid, size_t *oid_size)
{
  int result;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  result = _gnutls_x509_crt_get_extension_oid(cert, indx, oid, oid_size);
  if (result < 0) {
    return result;
  }

  return 0;
}

/**
 * gnutls_x509_crt_get_extension_info:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @indx: Specifies which extension OID to send. Use (0) to get the first one.
 * @oid: a pointer to a structure to hold the OID
 * @oid_size: initially holds the maximum size of @oid, on return
 *   holds actual size of @oid.
 * @critical: output variable with critical flag, may be NULL.
 *
 * This function will return the requested extension OID in the
 * certificate, and the critical flag for it.  The extension OID will
 * be stored as a string in the provided buffer.  Use
 * gnutls_x509_crt_get_extension() to extract the data.
 *
 * If the buffer provided is not long enough to hold the output, then
 * @oid_size is updated and %GNUTLS_E_SHORT_MEMORY_BUFFER will be
 * returned. The @oid returned will be null terminated, although
 * @oid_size will not account for the trailing null (the latter is not
 * true for GnuTLS prior to 3.6.0).
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,
 *   otherwise a negative error code is returned.  If you have reached the
 *   last extension available %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
 *   will be returned.
 **/
int gnutls_x509_crt_get_extension_info(gnutls_x509_crt_t cert, unsigned indx,
               void *oid, size_t *oid_size,
               unsigned int *critical)
{
  int result;
  char str_critical[10];
  char name[MAX_NAME_SIZE];
  int len;

  if (!cert) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  snprintf(name, sizeof(name), "tbsCertificate.extensions.?%u.extnID",
     indx + 1);

  len = *oid_size;
  result = asn1_read_value(cert->cert, name, oid, &len);
  *oid_size = len;

  if (result == ASN1_ELEMENT_NOT_FOUND)
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
  else if (result != ASN1_SUCCESS) {
    gnutls_assert();
    return _gnutls_asn2err(result);
  }

  /* remove any trailing null */
  if (oid && len > 0 && ((uint8_t *)oid)[len - 1] == 0)
    (*oid_size)--;

  if (critical) {
    snprintf(name, sizeof(name),
       "tbsCertificate.extensions.?%u.critical", indx + 1);
    len = sizeof(str_critical);
    result = asn1_read_value(cert->cert, name, str_critical, &len);
    if (result != ASN1_SUCCESS) {
      gnutls_assert();
      return _gnutls_asn2err(result);
    }

    if (str_critical[0] == 'T')
      *critical = 1;
    else
      *critical = 0;
  }

  return 0;
}

/**
 * gnutls_x509_crt_get_extension_data:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @indx: Specifies which extension OID to send. Use (0) to get the first one.
 * @data: a pointer to a structure to hold the data (may be null)
 * @sizeof_data: initially holds the size of @data
 *
 * This function will return the requested extension data in the
 * certificate.  The extension data will be stored in the
 * provided buffer.
 *
 * Use gnutls_x509_crt_get_extension_info() to extract the OID and
 * critical flag.  Use gnutls_x509_crt_get_extension_by_oid() instead,
 * if you want to get data indexed by the extension OID rather than
 * sequence.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,
 *   otherwise a negative error code is returned.  If you have reached the
 *   last extension available %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
 *   will be returned.
 **/
int gnutls_x509_crt_get_extension_data(gnutls_x509_crt_t cert, unsigned indx,
               void *data, size_t *sizeof_data)
{
  int result, len;
  char name[MAX_NAME_SIZE];

  if (!cert) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  snprintf(name, sizeof(name), "tbsCertificate.extensions.?%u.extnValue",
     indx + 1);

  len = *sizeof_data;
  result = asn1_read_value(cert->cert, name, data, &len);
  *sizeof_data = len;

  if (result == ASN1_ELEMENT_NOT_FOUND) {
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
  } else if (result == ASN1_MEM_ERROR && data == NULL) {
    /* normally we should return GNUTLS_E_SHORT_MEMORY_BUFFER,
     * but we haven't done that for long time, so use
     * backwards compatible behavior */
    return 0;
  } else if (result != ASN1_SUCCESS) {
    gnutls_assert();
    return _gnutls_asn2err(result);
  }

  return 0;
}

/**
 * gnutls_x509_crt_get_raw_issuer_dn:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @dn: will hold the starting point of the DN
 *
 * This function will return a pointer to the DER encoded DN structure
 * and the length. This points to allocated data that must be free'd using gnutls_free().
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.or a negative error code on error.
 *
 **/
int gnutls_x509_crt_get_raw_issuer_dn(gnutls_x509_crt_t cert,
              gnutls_datum_t *dn)
{
  if (cert->raw_issuer_dn.size > 0 && cert->modified == 0) {
    return _gnutls_set_datum(dn, cert->raw_issuer_dn.data,
           cert->raw_issuer_dn.size);
  } else {
    return _gnutls_x509_get_raw_field(
      cert->cert, "tbsCertificate.issuer.rdnSequence", dn);
  }
}

/**
 * gnutls_x509_crt_get_raw_dn:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @dn: will hold the starting point of the DN
 *
 * This function will return a pointer to the DER encoded DN structure and
 * the length. This points to allocated data that must be free'd using gnutls_free().
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value. or a negative error code on error.
 *
 **/
int gnutls_x509_crt_get_raw_dn(gnutls_x509_crt_t cert, gnutls_datum_t *dn)
{
  if (cert->raw_dn.size > 0 && cert->modified == 0) {
    return _gnutls_set_datum(dn, cert->raw_dn.data,
           cert->raw_dn.size);
  } else {
    return _gnutls_x509_get_raw_field(
      cert->cert, "tbsCertificate.subject.rdnSequence", dn);
  }
}

static int get_dn(gnutls_x509_crt_t cert, const char *whom,
      gnutls_x509_dn_t *dn, unsigned subject)
{
  gnutls_x509_dn_st *store;

  if (subject)
    store = &cert->dn;
  else
    store = &cert->idn;

  store->asn = asn1_find_node(cert->cert, whom);
  if (!store->asn)
    return GNUTLS_E_ASN1_ELEMENT_NOT_FOUND;

  *dn = store;

  return 0;
}

/**
 * gnutls_x509_crt_get_subject:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @dn: output variable with pointer to uint8_t DN.
 *
 * Return the Certificate's Subject DN as a %gnutls_x509_dn_t data type,
 * that can be decoded using gnutls_x509_dn_get_rdn_ava().
 *
 * Note that @dn should be treated as constant. Because it points
 * into the @cert object, you should not use @dn after @cert is
 * deallocated.
 *
 * Returns: Returns 0 on success, or an error code.
 **/
int gnutls_x509_crt_get_subject(gnutls_x509_crt_t cert, gnutls_x509_dn_t *dn)
{
  return get_dn(cert, "tbsCertificate.subject.rdnSequence", dn, 1);
}

/**
 * gnutls_x509_crt_get_issuer:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @dn: output variable with pointer to uint8_t DN
 *
 * Return the Certificate's Issuer DN as a %gnutls_x509_dn_t data type,
 * that can be decoded using gnutls_x509_dn_get_rdn_ava().
 *
 * Note that @dn should be treated as constant. Because it points
 * into the @cert object, you should not use @dn after @cert is
 * deallocated.
 *
 * Returns: Returns 0 on success, or an error code.
 **/
int gnutls_x509_crt_get_issuer(gnutls_x509_crt_t cert, gnutls_x509_dn_t *dn)
{
  return get_dn(cert, "tbsCertificate.issuer.rdnSequence", dn, 0);
}

/**
 * gnutls_x509_crt_get_fingerprint:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @algo: is a digest algorithm
 * @buf: a pointer to a structure to hold the fingerprint (may be null)
 * @buf_size: initially holds the size of @buf
 *
 * This function will calculate and copy the certificate's fingerprint
 * in the provided buffer. The fingerprint is a hash of the DER-encoded
 * data of the certificate.
 *
 * If the buffer is null then only the size will be filled.
 *
 * Returns: %GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is
 *   not long enough, and in that case the *buf_size will be updated
 *   with the required size.  On success 0 is returned.
 **/
int gnutls_x509_crt_get_fingerprint(gnutls_x509_crt_t cert,
            gnutls_digest_algorithm_t algo, void *buf,
            size_t *buf_size)
{
  uint8_t *cert_buf;
  int cert_buf_size;
  int result;
  gnutls_datum_t tmp;

  if (buf_size == 0 || cert == NULL) {
    return GNUTLS_E_INVALID_REQUEST;
  }

  cert_buf_size = 0;
  result = asn1_der_coding(cert->cert, "", NULL, &cert_buf_size, NULL);
  if (result != ASN1_MEM_ERROR) {
    gnutls_assert();
    return _gnutls_asn2err(result);
  }

  cert_buf = gnutls_malloc(cert_buf_size);
  if (cert_buf == NULL) {
    gnutls_assert();
    return GNUTLS_E_MEMORY_ERROR;
  }

  result =
    asn1_der_coding(cert->cert, "", cert_buf, &cert_buf_size, NULL);

  if (result != ASN1_SUCCESS) {
    gnutls_assert();
    gnutls_free(cert_buf);
    return _gnutls_asn2err(result);
  }

  tmp.data = cert_buf;
  tmp.size = cert_buf_size;

  result = gnutls_fingerprint(algo, &tmp, buf, buf_size);
  gnutls_free(cert_buf);

  return result;
}

/**
 * gnutls_x509_crt_export:
 * @cert: Holds the certificate
 * @format: the format of output params. One of PEM or DER.
 * @output_data: will contain a certificate PEM or DER encoded
 * @output_data_size: holds the size of output_data (and will be
 *   replaced by the actual size of parameters)
 *
 * This function will export the certificate to DER or PEM format.
 *
 * If the buffer provided is not long enough to hold the output, then
 * *output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will
 * be returned.
 *
 * If the structure is PEM encoded, it will have a header
 * of "BEGIN CERTIFICATE".
 *
 * Returns: In case of failure a negative error code will be
 *   returned, and 0 on success.
 **/
int gnutls_x509_crt_export(gnutls_x509_crt_t cert, gnutls_x509_crt_fmt_t format,
         void *output_data, size_t *output_data_size)
{
  gnutls_datum_t out;
  int ret;

  ret = gnutls_x509_crt_export2(cert, format, &out);
  if (ret < 0)
    return gnutls_assert_val(ret);

  if (format == GNUTLS_X509_FMT_PEM)
    ret = _gnutls_copy_string(&out, (uint8_t *)output_data,
            output_data_size);
  else
    ret = _gnutls_copy_data(&out, (uint8_t *)output_data,
          output_data_size);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = 0;
cleanup:
  gnutls_free(out.data);
  return ret;
}

/**
 * gnutls_x509_crt_export2:
 * @cert: Holds the certificate
 * @format: the format of output params. One of PEM or DER.
 * @out: will contain a certificate PEM or DER encoded
 *
 * This function will export the certificate to DER or PEM format.
 * The output buffer is allocated using gnutls_malloc().
 *
 * If the structure is PEM encoded, it will have a header
 * of "BEGIN CERTIFICATE".
 *
 * Returns: In case of failure a negative error code will be
 *   returned, and 0 on success.
 *
 * Since: 3.1.3
 **/
int gnutls_x509_crt_export2(gnutls_x509_crt_t cert,
          gnutls_x509_crt_fmt_t format, gnutls_datum_t *out)
{
  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  if (!cert->modified && cert->der.size) {
    if (format == GNUTLS_X509_FMT_DER)
      return _gnutls_set_datum(out, cert->der.data,
             cert->der.size);
    else {
      int ret = _gnutls_fbase64_encode(PEM_X509_CERT2,
               cert->der.data,
               cert->der.size, out);
      if (ret < 0)
        return ret;
      return 0;
    }
  }

  return _gnutls_x509_export_int2(cert->cert, format, PEM_X509_CERT2,
          out);
}

int _gnutls_get_key_id(gnutls_pk_params_st *params, unsigned char *output_data,
           size_t *output_data_size, unsigned flags)
{
  int ret = 0;
  gnutls_datum_t der = { NULL, 0 };
  gnutls_digest_algorithm_t hash = GNUTLS_DIG_SHA1;
  unsigned int digest_len;

  if ((flags & GNUTLS_KEYID_USE_SHA512) ||
      (flags & GNUTLS_KEYID_USE_BEST_KNOWN))
    hash = GNUTLS_DIG_SHA512;
  else if (flags & GNUTLS_KEYID_USE_SHA256)
    hash = GNUTLS_DIG_SHA256;

  digest_len = _gnutls_hash_get_algo_len(hash_to_entry(hash));

  if (output_data == NULL || *output_data_size < digest_len) {
    gnutls_assert();
    *output_data_size = digest_len;
    return GNUTLS_E_SHORT_MEMORY_BUFFER;
  }

  ret = _gnutls_x509_encode_PKI_params(&der, params);
  if (ret < 0)
    return gnutls_assert_val(ret);

  ret = _gnutls_hash_fast(hash, der.data, der.size, output_data);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }
  *output_data_size = digest_len;

  ret = 0;

cleanup:

  _gnutls_free_datum(&der);
  return ret;
}

/**
 * gnutls_x509_crt_get_key_id:
 * @crt: Holds the certificate
 * @flags: should be one of the flags from %gnutls_keyid_flags_t
 * @output_data: will contain the key ID
 * @output_data_size: holds the size of output_data (and will be
 *   replaced by the actual size of parameters)
 *
 * This function will return a unique ID that depends on the public
 * key parameters. This ID can be used in checking whether a
 * certificate corresponds to the given private key.
 *
 * If the buffer provided is not long enough to hold the output, then
 * *output_data_size is updated and GNUTLS_E_SHORT_MEMORY_BUFFER will
 * be returned.  The output will normally be a SHA-1 hash output,
 * which is 20 bytes.
 *
 * Returns: In case of failure a negative error code will be
 *   returned, and 0 on success.
 **/
int gnutls_x509_crt_get_key_id(gnutls_x509_crt_t crt, unsigned int flags,
             unsigned char *output_data,
             size_t *output_data_size)
{
  int ret = 0;
  gnutls_pk_params_st params;

  if (crt == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  /* initializes params */
  ret = _gnutls_x509_crt_get_mpis(crt, &params);
  if (ret < 0) {
    gnutls_assert();
    return ret;
  }

  ret = _gnutls_get_key_id(&params, output_data, output_data_size, flags);

  gnutls_pk_params_release(&params);

  return ret;
}

static int crl_issuer_matches(gnutls_x509_crl_t crl, gnutls_x509_crt_t cert)
{
  if (_gnutls_x509_compare_raw_dn(&crl->raw_issuer_dn,
          &cert->raw_issuer_dn) != 0)
    return 1;
  else
    return 0;
}

/* This is exactly as gnutls_x509_crt_check_revocation() except that
 * it calls func.
 */
int _gnutls_x509_crt_check_revocation(gnutls_x509_crt_t cert,
              const gnutls_x509_crl_t *crl_list,
              int crl_list_length,
              gnutls_verify_output_function func)
{
  uint8_t serial[128];
  uint8_t cert_serial[128];
  size_t serial_size, cert_serial_size;
  int ret, j;
  gnutls_x509_crl_iter_t iter = NULL;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  for (j = 0; j < crl_list_length; j++) { /* do for all the crls */

    /* Step 1. check if issuer's DN match
     */
    ret = crl_issuer_matches(crl_list[j], cert);
    if (ret == 0) {
      /* issuers do not match so don't even
       * bother checking.
       */
      gnutls_assert();
      continue;
    }

    /* Step 2. Read the certificate's serial number
     */
    cert_serial_size = sizeof(cert_serial);
    ret = gnutls_x509_crt_get_serial(cert, cert_serial,
             &cert_serial_size);
    if (ret < 0) {
      gnutls_assert();
      return ret;
    }

    /* Step 3. cycle through the CRL serials and compare with
     *   certificate serial we have.
     */

    iter = NULL;
    do {
      serial_size = sizeof(serial);
      ret = gnutls_x509_crl_iter_crt_serial(
        crl_list[j], &iter, serial, &serial_size, NULL);
      if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) {
        break;
      } else if (ret < 0) {
        gnutls_assert();
        goto fail;
      }

      if (serial_size == cert_serial_size) {
        if (memcmp(serial, cert_serial, serial_size) ==
            0) {
          /* serials match */
          if (func)
            func(cert, NULL, crl_list[j],
                 GNUTLS_CERT_REVOKED |
                   GNUTLS_CERT_INVALID);
          ret = 1; /* revoked! */
          goto fail;
        }
      }
    } while (1);

    gnutls_x509_crl_iter_deinit(iter);
    iter = NULL;

    if (func)
      func(cert, NULL, crl_list[j], 0);
  }
  return 0; /* not revoked. */

fail:
  gnutls_x509_crl_iter_deinit(iter);
  return ret;
}

/**
 * gnutls_x509_crt_check_revocation:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @crl_list: should contain a list of gnutls_x509_crl_t types
 * @crl_list_length: the length of the crl_list
 *
 * This function will check if the given certificate is
 * revoked.  It is assumed that the CRLs have been verified before.
 *
 * Returns: 0 if the certificate is NOT revoked, and 1 if it is.  A
 * negative error code is returned on error.
 **/
int gnutls_x509_crt_check_revocation(gnutls_x509_crt_t cert,
             const gnutls_x509_crl_t *crl_list,
             unsigned crl_list_length)
{
  return _gnutls_x509_crt_check_revocation(cert, crl_list,
             crl_list_length, NULL);
}

/**
 * gnutls_x509_crt_check_key_purpose:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @purpose: a key purpose OID (e.g., %GNUTLS_KP_CODE_SIGNING)
 * @flags: zero or %GNUTLS_KP_FLAG_DISALLOW_ANY
 *
 * This function will check whether the given certificate matches
 * the provided key purpose. If @flags contains %GNUTLS_KP_FLAG_ALLOW_ANY then
 * it a certificate marked for any purpose will not match.
 *
 * Returns: zero if the key purpose doesn't match, and non-zero otherwise.
 *
 * Since: 3.5.6
 **/
unsigned gnutls_x509_crt_check_key_purpose(gnutls_x509_crt_t cert,
             const char *purpose, unsigned flags)
{
  return _gnutls_check_key_purpose(
    cert, purpose, (flags & GNUTLS_KP_FLAG_DISALLOW_ANY) ? 1 : 0);
}

/**
 * gnutls_x509_crt_get_preferred_hash_algorithm:
 * @crt: Holds the certificate
 * @hash: The result of the call with the hash algorithm used for signature
 * @mand: If non-zero it means that the algorithm MUST use this hash. May be %NULL.
 *
 * This function will read the certificate and return the appropriate digest
 * algorithm to use for signing with this certificate. Some certificates (i.e.
 * DSA might not be able to sign without the preferred algorithm).
 *
 * Deprecated: Please use gnutls_pubkey_get_preferred_hash_algorithm().
 *
 * Returns: the 0 if the hash algorithm is found. A negative error code is
 * returned on error.
 *
 * Since: 2.12.0
 **/
int gnutls_x509_crt_get_preferred_hash_algorithm(gnutls_x509_crt_t crt,
             gnutls_digest_algorithm_t *hash,
             unsigned int *mand)
{
  int ret;
  gnutls_pubkey_t pubkey;

  if (crt == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  ret = gnutls_pubkey_init(&pubkey);
  if (ret < 0)
    return gnutls_assert_val(ret);

  ret = gnutls_pubkey_import_x509(pubkey, crt, 0);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = gnutls_pubkey_get_preferred_hash_algorithm(pubkey, hash, mand);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

cleanup:
  gnutls_pubkey_deinit(pubkey);
  return ret;
}

/**
 * gnutls_x509_crt_get_crl_dist_points:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @seq: specifies the sequence number of the distribution point (0 for the first one, 1 for the second etc.)
 * @san: is the place where the distribution point will be copied to
 * @san_size: holds the size of ret.
 * @reason_flags: Revocation reasons. An ORed sequence of flags from %gnutls_x509_crl_reason_flags_t.
 * @critical: will be non-zero if the extension is marked as critical (may be null)
 *
 * This function retrieves the CRL distribution points (2.5.29.31),
 * contained in the given certificate in the X509v3 Certificate
 * Extensions.
 *
 * Returns: %GNUTLS_E_SHORT_MEMORY_BUFFER and updates @ret_size if
 *   @ret_size is not enough to hold the distribution point, or the
 *   type of the distribution point if everything was ok. The type is
 *   one of the enumerated %gnutls_x509_subject_alt_name_t.  If the
 *   certificate does not have an Alternative name with the specified
 *   sequence number then %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is
 *   returned.
 **/
int gnutls_x509_crt_get_crl_dist_points(gnutls_x509_crt_t cert,
          unsigned int seq, void *san,
          size_t *san_size,
          unsigned int *reason_flags,
          unsigned int *critical)
{
  int ret;
  gnutls_datum_t dist_points = { NULL, 0 };
  unsigned type;
  gnutls_x509_crl_dist_points_t cdp = NULL;
  gnutls_datum_t t_san;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  ret = gnutls_x509_crl_dist_points_init(&cdp);
  if (ret < 0)
    return gnutls_assert_val(ret);

  if (reason_flags)
    *reason_flags = 0;

  ret = _gnutls_x509_crt_get_extension(cert, "2.5.29.31", 0, &dist_points,
               critical);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  if (dist_points.size == 0 || dist_points.data == NULL) {
    gnutls_assert();
    ret = GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
    goto cleanup;
  }

  ret = gnutls_x509_ext_import_crl_dist_points(&dist_points, cdp, 0);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = gnutls_x509_crl_dist_points_get(cdp, seq, &type, &t_san,
                reason_flags);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = _gnutls_copy_string(&t_san, san, san_size);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = type;

cleanup:
  _gnutls_free_datum(&dist_points);
  if (cdp != NULL)
    gnutls_x509_crl_dist_points_deinit(cdp);

  return ret;
}

/**
 * gnutls_x509_crt_get_key_purpose_oid:
 * @cert: should contain a #gnutls_x509_crt_t type
 * @indx: This specifies which OID to return. Use (0) to get the first one.
 * @oid: a pointer to a buffer to hold the OID (may be null)
 * @oid_size: initially holds the size of @oid
 * @critical: output flag to indicate criticality of extension
 *
 * This function will extract the key purpose OIDs of the Certificate
 * specified by the given index.  These are stored in the Extended Key
 * Usage extension (2.5.29.37) See the GNUTLS_KP_* definitions for
 * human readable names.
 *
 * If @oid is null then only the size will be filled. The @oid
 * returned will be null terminated, although @oid_size will not
 * account for the trailing null.
 *
 * Returns: %GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is
 *   not long enough, and in that case the *oid_size will be updated
 *   with the required size.  On success 0 is returned.
 **/
int gnutls_x509_crt_get_key_purpose_oid(gnutls_x509_crt_t cert, unsigned indx,
          void *oid, size_t *oid_size,
          unsigned int *critical)
{
  int ret;
  gnutls_datum_t ext;
  gnutls_x509_key_purposes_t p = NULL;
  gnutls_datum_t out;

  if (cert == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  if (oid)
    memset(oid, 0, *oid_size);
  else
    *oid_size = 0;

  if ((ret = _gnutls_x509_crt_get_extension(cert, "2.5.29.37", 0, &ext,
              critical)) < 0) {
    return ret;
  }

  if (ext.size == 0 || ext.data == NULL) {
    gnutls_assert();
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
  }

  ret = gnutls_x509_key_purpose_init(&p);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = gnutls_x509_ext_import_key_purposes(&ext, p, 0);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = gnutls_x509_key_purpose_get(p, indx, &out);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = _gnutls_copy_string(&out, oid, oid_size);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = 0;

cleanup:
  gnutls_free(ext.data);
  if (p != NULL)
    gnutls_x509_key_purpose_deinit(p);
  return ret;
}

/**
 * gnutls_x509_crt_get_pk_rsa_raw:
 * @crt: Holds the certificate
 * @m: will hold the modulus
 * @e: will hold the public exponent
 *
 * This function will export the RSA public key's parameters found in
 * the given structure.  The new parameters will be allocated using
 * gnutls_malloc() and will be stored in the appropriate datum.
 *
 * Returns: %GNUTLS_E_SUCCESS on success, otherwise a negative error code.
 **/
int gnutls_x509_crt_get_pk_rsa_raw(gnutls_x509_crt_t crt, gnutls_datum_t *m,
           gnutls_datum_t *e)
{
  int ret;
  gnutls_pubkey_t pubkey;

  if (crt == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  ret = gnutls_pubkey_init(&pubkey);
  if (ret < 0)
    return gnutls_assert_val(ret);

  ret = gnutls_pubkey_import_x509(pubkey, crt, 0);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = gnutls_pubkey_export_rsa_raw(pubkey, m, e);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

cleanup:
  gnutls_pubkey_deinit(pubkey);
  return ret;
}

/**
 * gnutls_x509_crt_get_pk_ecc_raw:
 * @crt: Holds the certificate
 * @curve: will hold the curve
 * @x: will hold the x-coordinate
 * @y: will hold the y-coordinate
 *
 * This function will export the ECC public key's parameters found in
 * the given certificate.  The new parameters will be allocated using
 * gnutls_malloc() and will be stored in the appropriate datum.
 *
 * In EdDSA curves the @y parameter will be %NULL and the other parameters
 * will be in the native format for the curve.
 *
 * Returns: %GNUTLS_E_SUCCESS on success, otherwise a negative error code.
 *
 * Since: 3.4.1
 **/
int gnutls_x509_crt_get_pk_ecc_raw(gnutls_x509_crt_t crt,
           gnutls_ecc_curve_t *curve, gnutls_datum_t *x,
           gnutls_datum_t *y)
{
  int ret;
  gnutls_pubkey_t pubkey;

  if (crt == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  ret = gnutls_pubkey_init(&pubkey);
  if (ret < 0)
    return gnutls_assert_val(ret);

  ret = gnutls_pubkey_import_x509(pubkey, crt, 0);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = gnutls_pubkey_export_ecc_raw(pubkey, curve, x, y);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

cleanup:
  gnutls_pubkey_deinit(pubkey);
  return ret;
}

/**
 * gnutls_x509_crt_get_pk_gost_raw:
 * @crt: Holds the certificate
 * @curve: will hold the curve
 * @digest: will hold the digest
 * @paramset: will hold the GOST parameter set ID
 * @x: will hold the x-coordinate
 * @y: will hold the y-coordinate
 *
 * This function will export the GOST public key's parameters found in
 * the given certificate.  The new parameters will be allocated using
 * gnutls_malloc() and will be stored in the appropriate datum.
 *
 * Returns: %GNUTLS_E_SUCCESS on success, otherwise a negative error code.
 *
 * Since: 3.6.3
 **/
int gnutls_x509_crt_get_pk_gost_raw(gnutls_x509_crt_t crt,
            gnutls_ecc_curve_t *curve,
            gnutls_digest_algorithm_t *digest,
            gnutls_gost_paramset_t *paramset,
            gnutls_datum_t *x, gnutls_datum_t *y)
{
  int ret;
  gnutls_pubkey_t pubkey;

  if (crt == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  ret = gnutls_pubkey_init(&pubkey);
  if (ret < 0)
    return gnutls_assert_val(ret);

  ret = gnutls_pubkey_import_x509(pubkey, crt, 0);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = gnutls_pubkey_export_gost_raw2(pubkey, curve, digest, paramset, x,
               y, 0);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

cleanup:
  gnutls_pubkey_deinit(pubkey);
  return ret;
}

/**
 * gnutls_x509_crt_get_pk_dsa_raw:
 * @crt: Holds the certificate
 * @p: will hold the p
 * @q: will hold the q
 * @g: will hold the g
 * @y: will hold the y
 *
 * This function will export the DSA public key's parameters found in
 * the given certificate.  The new parameters will be allocated using
 * gnutls_malloc() and will be stored in the appropriate datum.
 *
 * Returns: %GNUTLS_E_SUCCESS on success, otherwise a negative error code.
 **/
int gnutls_x509_crt_get_pk_dsa_raw(gnutls_x509_crt_t crt, gnutls_datum_t *p,
           gnutls_datum_t *q, gnutls_datum_t *g,
           gnutls_datum_t *y)
{
  int ret;
  gnutls_pubkey_t pubkey;

  if (crt == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  ret = gnutls_pubkey_init(&pubkey);
  if (ret < 0)
    return gnutls_assert_val(ret);

  ret = gnutls_pubkey_import_x509(pubkey, crt, 0);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  ret = gnutls_pubkey_export_dsa_raw(pubkey, p, q, g, y);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

cleanup:
  gnutls_pubkey_deinit(pubkey);
  return ret;
}

/**
 * gnutls_x509_crt_list_import2:
 * @certs: Will hold the parsed certificate list.
 * @size: It will contain the size of the list.
 * @data: The PEM encoded certificate.
 * @format: One of DER or PEM.
 * @flags: must be (0) or an OR'd sequence of gnutls_certificate_import_flags.
 *
 * This function will convert the given PEM encoded certificate list
 * to the native gnutls_x509_crt_t format. The output will be stored
 * in @certs which will be allocated and initialized.
 *
 * If the Certificate is PEM encoded it should have a header of "X509
 * CERTIFICATE", or "CERTIFICATE".
 *
 * To deinitialize @certs, you need to deinitialize each crt structure
 * independently, and use gnutls_free() at @certs.
 *
 * Returns: %GNUTLS_E_SUCCESS on success, otherwise a negative error code.
 *
 * Since: 3.0
 **/
int gnutls_x509_crt_list_import2(gnutls_x509_crt_t **certs, unsigned int *size,
         const gnutls_datum_t *data,
         gnutls_x509_crt_fmt_t format,
         unsigned int flags)
{
  unsigned int init = 1024;
  int ret;

  *certs = _gnutls_reallocarray(NULL, init, sizeof(gnutls_x509_crt_t));
  if (*certs == NULL) {
    gnutls_assert();
    return GNUTLS_E_MEMORY_ERROR;
  }

  ret = gnutls_x509_crt_list_import(
    *certs, &init, data, format,
    flags | GNUTLS_X509_CRT_LIST_IMPORT_FAIL_IF_EXCEED);
  if (ret == GNUTLS_E_SHORT_MEMORY_BUFFER) {
    *certs = _gnutls_reallocarray_fast(*certs, init,
               sizeof(gnutls_x509_crt_t));
    if (*certs == NULL) {
      gnutls_assert();
      return GNUTLS_E_MEMORY_ERROR;
    }

    ret = gnutls_x509_crt_list_import(*certs, &init, data, format,
              flags);
  }

  if (ret < 0) {
    gnutls_free(*certs);
    return ret;
  }

  *size = init;
  return 0;
}

/**
 * gnutls_x509_crt_list_import:
 * @certs: Indicates where the parsed list will be copied to. Must not be initialized.
 * @cert_max: Initially must hold the maximum number of certs. It will be updated with the number of certs available.
 * @data: The PEM encoded certificate.
 * @format: One of DER or PEM.
 * @flags: must be (0) or an OR'd sequence of gnutls_certificate_import_flags.
 *
 * This function will convert the given PEM encoded certificate list
 * to the native gnutls_x509_crt_t format. The output will be stored
 * in @certs.  They will be automatically initialized.
 *
 * The flag %GNUTLS_X509_CRT_LIST_IMPORT_FAIL_IF_EXCEED will cause
 * import to fail if the certificates in the provided buffer are more
 * than the available structures. The %GNUTLS_X509_CRT_LIST_FAIL_IF_UNSORTED
 * flag will cause the function to fail if the provided list is not
 * sorted from subject to issuer.
 *
 * If the Certificate is PEM encoded it should have a header of "X509
 * CERTIFICATE", or "CERTIFICATE".
 *
 * Returns: the number of certificates read or a negative error value.
 **/
int gnutls_x509_crt_list_import(gnutls_x509_crt_t *certs,
        unsigned int *cert_max,
        const gnutls_datum_t *data,
        gnutls_x509_crt_fmt_t format,
        unsigned int flags)
{
  int size;
  const char *ptr;
  gnutls_datum_t tmp;
  int ret, nocopy = 0;
  unsigned int count = 0, j, copied = 0;

  if (format == GNUTLS_X509_FMT_DER) {
    if (*cert_max < 1) {
      *cert_max = 1;
      return GNUTLS_E_SHORT_MEMORY_BUFFER;
    }

    count = 1; /* import only the first one */

    ret = gnutls_x509_crt_init(&certs[0]);
    if (ret < 0) {
      gnutls_assert();
      goto error;
    }

    ret = gnutls_x509_crt_import(certs[0], data, format);
    if (ret < 0) {
      gnutls_assert();
      goto error;
    }

    *cert_max = 1;
    return 1;
  }

  /* move to the certificate
   */
  ptr = memmem(data->data, data->size, PEM_CERT_SEP,
         sizeof(PEM_CERT_SEP) - 1);
  if (ptr == NULL)
    ptr = memmem(data->data, data->size, PEM_CERT_SEP2,
           sizeof(PEM_CERT_SEP2) - 1);

  if (ptr == NULL)
    return gnutls_assert_val(GNUTLS_E_NO_CERTIFICATE_FOUND);

  count = 0;

  do {
    if (count >= *cert_max) {
      if (!(flags &
            GNUTLS_X509_CRT_LIST_IMPORT_FAIL_IF_EXCEED))
        break;
      else
        nocopy = 1;
    }

    if (!nocopy) {
      ret = gnutls_x509_crt_init(&certs[count]);
      if (ret < 0) {
        gnutls_assert();
        goto error;
      }

      tmp.data = (void *)ptr;
      tmp.size = data->size - (ptr - (char *)data->data);

      ret = gnutls_x509_crt_import(certs[count], &tmp,
                 GNUTLS_X509_FMT_PEM);
      if (ret < 0) {
        count++;
        gnutls_assert();
        goto error;
      }

      copied++;
    }

    /* now we move ptr after the pem header
     */
    ptr++;
    /* find the next certificate (if any)
     */
    size = data->size - (ptr - (char *)data->data);

    if (size > 0) {
      char *ptr2;

      ptr2 = memmem(ptr, size, PEM_CERT_SEP,
              sizeof(PEM_CERT_SEP) - 1);
      if (ptr2 == NULL)
        ptr2 = memmem(ptr, size, PEM_CERT_SEP2,
                sizeof(PEM_CERT_SEP2) - 1);

      ptr = ptr2;
    } else
      ptr = NULL;

    count++;
  } while (ptr != NULL);

  *cert_max = count;

  if (nocopy == 0) {
    if (flags & GNUTLS_X509_CRT_LIST_SORT && *cert_max > 1) {
      if (*cert_max > DEFAULT_MAX_VERIFY_DEPTH) {
        ret = GNUTLS_E_UNIMPLEMENTED_FEATURE;
        goto error;
      }
      count = _gnutls_sort_clist(certs, *cert_max);
      if (count < *cert_max) {
        for (j = count; j < *cert_max; j++) {
          gnutls_x509_crt_deinit(certs[j]);
        }
      }
      *cert_max = count;
    }

    if (flags & GNUTLS_X509_CRT_LIST_FAIL_IF_UNSORTED) {
      ret = _gnutls_check_if_sorted(certs, *cert_max);
      if (ret < 0) {
        gnutls_assert();
        goto error;
      }
    }

    return count;
  } else {
    count = copied;
    ret = GNUTLS_E_SHORT_MEMORY_BUFFER;
  }

error:
  for (j = 0; j < count; j++)
    gnutls_x509_crt_deinit(certs[j]);
  return ret;
}

/**
 * gnutls_x509_crt_get_subject_unique_id:
 * @crt: Holds the certificate
 * @buf: user allocated memory buffer, will hold the unique id
 * @buf_size: size of user allocated memory buffer (on input), will hold
 * actual size of the unique ID on return.
 *
 * This function will extract the subjectUniqueID value (if present) for
 * the given certificate.
 *
 * If the user allocated memory buffer is not large enough to hold the
 * full subjectUniqueID, then a GNUTLS_E_SHORT_MEMORY_BUFFER error will be
 * returned, and buf_size will be set to the actual length.
 *
 * This function had a bug prior to 3.4.8 that prevented the setting
 * of %NULL @buf to discover the @buf_size. To use this function safely
 * with the older versions the @buf must be a valid buffer that can hold
 * at least a single byte if @buf_size is zero.
 *
 * Returns: %GNUTLS_E_SUCCESS on success, otherwise a negative error code.
 **/
int gnutls_x509_crt_get_subject_unique_id(gnutls_x509_crt_t crt, char *buf,
            size_t *buf_size)
{
  int result;
  gnutls_datum_t datum = { NULL, 0 };

  result = _gnutls_x509_read_value(
    crt->cert, "tbsCertificate.subjectUniqueID", &datum);
  if (result < 0)
    return gnutls_assert_val(result);

  if (datum.size > *buf_size) { /* then we're not going to fit */
    *buf_size = datum.size;
    result = GNUTLS_E_SHORT_MEMORY_BUFFER;
  } else {
    *buf_size = datum.size;
    memcpy(buf, datum.data, datum.size);
  }

  _gnutls_free_datum(&datum);

  return result;
}

/**
 * gnutls_x509_crt_get_issuer_unique_id:
 * @crt: Holds the certificate
 * @buf: user allocated memory buffer, will hold the unique id
 * @buf_size: size of user allocated memory buffer (on input), will hold
 * actual size of the unique ID on return.
 *
 * This function will extract the issuerUniqueID value (if present) for
 * the given certificate.
 *
 * If the user allocated memory buffer is not large enough to hold the
 * full subjectUniqueID, then a GNUTLS_E_SHORT_MEMORY_BUFFER error will be
 * returned, and buf_size will be set to the actual length.
 *
 * This function had a bug prior to 3.4.8 that prevented the setting
 * of %NULL @buf to discover the @buf_size. To use this function safely
 * with the older versions the @buf must be a valid buffer that can hold
 * at least a single byte if @buf_size is zero.
 *
 * Returns: %GNUTLS_E_SUCCESS on success, otherwise a negative error code.
 *
 * Since: 2.12.0
 **/
int gnutls_x509_crt_get_issuer_unique_id(gnutls_x509_crt_t crt, char *buf,
           size_t *buf_size)
{
  int result;
  gnutls_datum_t datum = { NULL, 0 };

  result = _gnutls_x509_read_value(
    crt->cert, "tbsCertificate.issuerUniqueID", &datum);
  if (result < 0)
    return gnutls_assert_val(result);

  if (datum.size > *buf_size) { /* then we're not going to fit */
    *buf_size = datum.size;
    result = GNUTLS_E_SHORT_MEMORY_BUFFER;
  } else {
    *buf_size = datum.size;
    memcpy(buf, datum.data, datum.size);
  }

  _gnutls_free_datum(&datum);

  return result;
}

static int legacy_parse_aia(asn1_node src, unsigned int seq, int what,
          gnutls_datum_t *data)
{
  int len;
  char nptr[MAX_NAME_SIZE];
  int result;
  gnutls_datum_t d;
  const char *oid = NULL;

  seq++; /* 0->1, 1->2 etc */
  switch (what) {
  case GNUTLS_IA_ACCESSMETHOD_OID:
    snprintf(nptr, sizeof(nptr), "?%u.accessMethod", seq);
    break;

  case GNUTLS_IA_ACCESSLOCATION_GENERALNAME_TYPE:
    snprintf(nptr, sizeof(nptr), "?%u.accessLocation", seq);
    break;

  case GNUTLS_IA_CAISSUERS_URI:
    oid = GNUTLS_OID_AD_CAISSUERS;
    FALLTHROUGH;

  case GNUTLS_IA_OCSP_URI:
    if (oid == NULL)
      oid = GNUTLS_OID_AD_OCSP;
    {
      char tmpoid[MAX_OID_SIZE];
      snprintf(nptr, sizeof(nptr), "?%u.accessMethod", seq);
      len = sizeof(tmpoid);
      result = asn1_read_value(src, nptr, tmpoid, &len);

      if (result == ASN1_VALUE_NOT_FOUND ||
          result == ASN1_ELEMENT_NOT_FOUND)
        return gnutls_assert_val(
          GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);

      if (result != ASN1_SUCCESS) {
        gnutls_assert();
        return _gnutls_asn2err(result);
      }
      if ((unsigned)len != strlen(oid) + 1 ||
          memcmp(tmpoid, oid, len) != 0)
        return gnutls_assert_val(
          GNUTLS_E_UNKNOWN_ALGORITHM);
    }
    FALLTHROUGH;

  case GNUTLS_IA_URI:
    snprintf(nptr, sizeof(nptr),
       "?%u.accessLocation.uniformResourceIdentifier", seq);
    break;

  default:
    return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
  }

  len = 0;
  result = asn1_read_value(src, nptr, NULL, &len);
  if (result == ASN1_VALUE_NOT_FOUND || result == ASN1_ELEMENT_NOT_FOUND)
    return gnutls_assert_val(GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE);

  if (result != ASN1_MEM_ERROR) {
    gnutls_assert();
    return _gnutls_asn2err(result);
  }

  d.size = len;

  d.data = gnutls_malloc(d.size);
  if (d.data == NULL)
    return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

  result = asn1_read_value(src, nptr, d.data, &len);
  if (result != ASN1_SUCCESS) {
    gnutls_assert();
    gnutls_free(d.data);
    return _gnutls_asn2err(result);
  }

  if (data) {
    data->data = d.data;
    data->size = d.size;
  } else
    gnutls_free(d.data);

  return 0;
}

/**
 * gnutls_x509_crt_get_authority_info_access:
 * @crt: Holds the certificate
 * @seq: specifies the sequence number of the access descriptor (0 for the first one, 1 for the second etc.)
 * @what: what data to get, a #gnutls_info_access_what_t type.
 * @data: output data to be freed with gnutls_free().
 * @critical: pointer to output integer that is set to non-zero if the extension is marked as critical (may be %NULL)
 *
 * Note that a simpler API to access the authority info data is provided
 * by gnutls_x509_aia_get() and gnutls_x509_ext_import_aia().
 *
 * This function extracts the Authority Information Access (AIA)
 * extension, see RFC 5280 section 4.2.2.1 for more information.  The
 * AIA extension holds a sequence of AccessDescription (AD) data.
 *
 * The @seq input parameter is used to indicate which member of the
 * sequence the caller is interested in.  The first member is 0, the
 * second member 1 and so on.  When the @seq value is out of bounds,
 * %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned.
 *
 * The type of data returned in @data is specified via @what which
 * should be #gnutls_info_access_what_t values.
 *
 * If @what is %GNUTLS_IA_ACCESSMETHOD_OID then @data will hold the
 * accessMethod OID (e.g., "1.3.6.1.5.5.7.48.1").
 *
 * If @what is %GNUTLS_IA_ACCESSLOCATION_GENERALNAME_TYPE, @data will
 * hold the accessLocation GeneralName type (e.g.,
 * "uniformResourceIdentifier").
 *
 * If @what is %GNUTLS_IA_URI, @data will hold the accessLocation URI
 * data.  Requesting this @what value leads to an error if the
 * accessLocation is not of the "uniformResourceIdentifier" type.
 *
 * If @what is %GNUTLS_IA_OCSP_URI, @data will hold the OCSP URI.
 * Requesting this @what value leads to an error if the accessMethod
 * is not 1.3.6.1.5.5.7.48.1 aka OCSP, or if accessLocation is not of
 * the "uniformResourceIdentifier" type. In that case %GNUTLS_E_UNKNOWN_ALGORITHM
 * will be returned, and @seq should be increased and this function
 * called again.
 *
 * If @what is %GNUTLS_IA_CAISSUERS_URI, @data will hold the caIssuers
 * URI.  Requesting this @what value leads to an error if the
 * accessMethod is not 1.3.6.1.5.5.7.48.2 aka caIssuers, or if
 * accessLocation is not of the "uniformResourceIdentifier" type.
 * In that case handle as in %GNUTLS_IA_OCSP_URI.
 *
 * More @what values may be allocated in the future as needed.
 *
 * If @data is NULL, the function does the same without storing the
 * output data, that is, it will set @critical and do error checking
 * as usual.
 *
 * The value of the critical flag is returned in *@critical.  Supply a
 * NULL @critical if you want the function to make sure the extension
 * is non-critical, as required by RFC 5280.
 *
 * Returns: %GNUTLS_E_SUCCESS on success, %GNUTLS_E_INVALID_REQUEST on
 * invalid @crt, %GNUTLS_E_CONSTRAINT_ERROR if the extension is
 * incorrectly marked as critical (use a non-NULL @critical to
 * override), %GNUTLS_E_UNKNOWN_ALGORITHM if the requested OID does
 * not match (e.g., when using %GNUTLS_IA_OCSP_URI), otherwise a
 * negative error code.
 *
 * Since: 3.0
 **/
int gnutls_x509_crt_get_authority_info_access(gnutls_x509_crt_t crt,
                unsigned int seq, int what,
                gnutls_datum_t *data,
                unsigned int *critical)
{
  int ret;
  gnutls_datum_t aia;
  asn1_node c2 = NULL;

  if (crt == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  if ((ret = _gnutls_x509_crt_get_extension(crt, GNUTLS_OID_AIA, 0, &aia,
              critical)) < 0)
    return ret;

  if (aia.size == 0 || aia.data == NULL) {
    gnutls_assert();
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
  }

  if (critical && *critical)
    return GNUTLS_E_CONSTRAINT_ERROR;

  ret = asn1_create_element(_gnutls_get_pkix(),
          "PKIX1.AuthorityInfoAccessSyntax", &c2);
  if (ret != ASN1_SUCCESS) {
    gnutls_assert();
    _gnutls_free_datum(&aia);
    return _gnutls_asn2err(ret);
  }

  ret = _asn1_strict_der_decode(&c2, aia.data, aia.size, NULL);
  /* asn1_print_structure (stdout, c2, "", ASN1_PRINT_ALL); */
  _gnutls_free_datum(&aia);
  if (ret != ASN1_SUCCESS) {
    gnutls_assert();
    asn1_delete_structure(&c2);
    return _gnutls_asn2err(ret);
  }

  ret = legacy_parse_aia(c2, seq, what, data);

  asn1_delete_structure(&c2);
  if (ret < 0)
    gnutls_assert();

  return ret;
}

/**
 * gnutls_x509_crt_set_pin_function:
 * @crt: The certificate structure
 * @fn: the callback
 * @userdata: data associated with the callback
 *
 * This function will set a callback function to be used when
 * it is required to access a protected object. This function overrides
 * the global function set using gnutls_pkcs11_set_pin_function().
 *
 * Note that this callback is currently used only during the import
 * of a PKCS #11 certificate with gnutls_x509_crt_import_url().
 *
 * Since: 3.1.0
 *
 **/
void gnutls_x509_crt_set_pin_function(gnutls_x509_crt_t crt,
              gnutls_pin_callback_t fn, void *userdata)
{
  if (crt) {
    crt->pin.cb = fn;
    crt->pin.data = userdata;
  }
}

/**
 * gnutls_x509_crt_import_url:
 * @crt: A certificate of type #gnutls_x509_crt_t
 * @url: A PKCS 11 url
 * @flags: One of GNUTLS_PKCS11_OBJ_* flags for PKCS#11 URLs or zero otherwise
 *
 * This function will import a certificate present in a PKCS#11 token
 * or any type of back-end that supports URLs.
 *
 * In previous versions of gnutls this function was named
 * gnutls_x509_crt_import_pkcs11_url, and the old name is
 * an alias to this one.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 *
 * Since: 3.4.0
 **/
int gnutls_x509_crt_import_url(gnutls_x509_crt_t crt, const char *url,
             unsigned int flags)
{
  int ret;
  unsigned i;

  for (i = 0; i < _gnutls_custom_urls_size; i++) {
    if (strncmp(url, _gnutls_custom_urls[i].name,
          _gnutls_custom_urls[i].name_size) == 0) {
      if (_gnutls_custom_urls[i].import_crt) {
        ret = _gnutls_custom_urls[i].import_crt(
          crt, url, flags);
        goto cleanup;
      }
      break;
    }
  }

  if (strncmp(url, SYSTEM_URL, SYSTEM_URL_SIZE) == 0) {
    ret = _gnutls_x509_crt_import_system_url(crt, url);
#ifdef ENABLE_PKCS11
  } else if (strncmp(url, PKCS11_URL, PKCS11_URL_SIZE) == 0) {
    ret = _gnutls_x509_crt_import_pkcs11_url(crt, url, flags);
#endif
  } else {
    ret = gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
  }

cleanup:
  return ret;
}

/**
 * gnutls_x509_crt_list_import_url:
 * @certs: Will hold the allocated certificate list.
 * @size: It will contain the size of the list.
 * @url: A PKCS 11 url
 * @pin_fn: a PIN callback if not globally set
 * @pin_fn_userdata: parameter for the PIN callback
 * @flags: One of GNUTLS_PKCS11_OBJ_* flags for PKCS#11 URLs or zero otherwise
 *
 * This function will import a certificate chain present in a PKCS#11 token
 * or any type of back-end that supports URLs. The certificates
 * must be deinitialized afterwards using gnutls_x509_crt_deinit()
 * and the returned pointer must be freed using gnutls_free().
 *
 * The URI provided must be the first certificate in the chain; subsequent
 * certificates will be retrieved using gnutls_pkcs11_get_raw_issuer() or
 * equivalent functionality for the supported URI.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 *
 * Since: 3.6.3
 **/
int gnutls_x509_crt_list_import_url(gnutls_x509_crt_t **certs,
            unsigned int *size, const char *url,
            gnutls_pin_callback_t pin_fn,
            void *pin_fn_userdata, unsigned int flags)
{
  int ret;
  unsigned i;
  gnutls_x509_crt_t crts[DEFAULT_MAX_VERIFY_DEPTH];
  gnutls_datum_t issuer = { NULL, 0 };
  unsigned total = 0;

  memset(crts, 0, sizeof(crts));

  ret = gnutls_x509_crt_init(&crts[0]);
  if (ret < 0)
    return gnutls_assert_val(ret);

  gnutls_x509_crt_set_pin_function(crts[0], pin_fn, pin_fn_userdata);

  total = 1;

  ret = gnutls_x509_crt_import_url(crts[0], url, flags);
  if (ret < 0) {
    gnutls_assert();
    goto cleanup;
  }

  for (i = 1; i < DEFAULT_MAX_VERIFY_DEPTH; i++) {
    ret = _gnutls_get_raw_issuer(
      url, crts[i - 1], &issuer,
      flags | GNUTLS_PKCS11_OBJ_FLAG_RETRIEVE_ANY);
    if (ret < 0) {
      issuer.data = NULL;
      break;
    }

    if (gnutls_x509_crt_equals2(crts[i - 1], &issuer)) {
      gnutls_free(issuer.data);
      break;
    }

    ret = gnutls_x509_crt_init(&crts[i]);
    if (ret < 0) {
      gnutls_assert();
      goto cleanup;
    }

    total++;

    gnutls_x509_crt_set_pin_function(crts[i], pin_fn,
             pin_fn_userdata);

    ret = gnutls_x509_crt_import(crts[i], &issuer,
               GNUTLS_X509_FMT_DER);
    if (ret < 0) {
      gnutls_assert();
      goto cleanup;
    }

    gnutls_free(issuer.data);
  }

  *certs = _gnutls_reallocarray(NULL, total, sizeof(gnutls_x509_crt_t));
  if (*certs == NULL) {
    ret = GNUTLS_E_MEMORY_ERROR;
    goto cleanup;
  }

  memcpy(*certs, crts, total * sizeof(gnutls_x509_crt_t));
  *size = total;

  return 0;
cleanup:
  gnutls_free(issuer.data);
  for (i = 0; i < total; i++)
    gnutls_x509_crt_deinit(crts[i]);

  return ret;
}

/*-
 * gnutls_x509_crt_verify_data3:
 * @crt: Holds the certificate to verify with
 * @algo: The signature algorithm used
 * @flags: Zero or an OR list of #gnutls_certificate_verify_flags
 * @data: holds the signed data
 * @signature: contains the signature
 *
 * This function will verify the given signed data, using the
 * parameters from the certificate.
 *
 * Returns: In case of a verification failure %GNUTLS_E_PK_SIG_VERIFY_FAILED
 * is returned, %GNUTLS_E_EXPIRED or %GNUTLS_E_NOT_YET_ACTIVATED on expired
 * or not yet activated certificate and zero or positive code on success.
 *
 * Since: 3.5.6
 -*/
int gnutls_x509_crt_verify_data3(gnutls_x509_crt_t crt,
         gnutls_sign_algorithm_t algo,
         gnutls_typed_vdata_st *vdata,
         unsigned int vdata_size,
         const gnutls_datum_t *data,
         const gnutls_datum_t *signature,
         unsigned int flags)
{
  int ret;
  gnutls_pubkey_t pubkey;

  if (crt == NULL) {
    gnutls_assert();
    return GNUTLS_E_INVALID_REQUEST;
  }

  ret = gnutls_pubkey_init(&pubkey);
  if (ret < 0)
    return gnutls_assert_val(ret);

  ret = gnutls_pubkey_import_x509(pubkey, crt, 0);
  if (ret < 0)
    return gnutls_assert_val(ret);

  ret = gnutls_pubkey_verify_data2(pubkey, algo, flags, data, signature);
  gnutls_pubkey_deinit(pubkey);

  if (ret >= 0) {
    time_t now = gnutls_time(0);
    int res;
    unsigned usage, i;

    if (!(flags & GNUTLS_VERIFY_DISABLE_TRUSTED_TIME_CHECKS) ||
        !(flags & GNUTLS_VERIFY_DISABLE_TIME_CHECKS)) {
      if (now > gnutls_x509_crt_get_expiration_time(crt)) {
        return gnutls_assert_val(GNUTLS_E_EXPIRED);
      }

      if (now < gnutls_x509_crt_get_activation_time(crt)) {
        return gnutls_assert_val(
          GNUTLS_E_NOT_YET_ACTIVATED);
      }
    }

    res = gnutls_x509_crt_get_key_usage(crt, &usage, NULL);
    if (res >= 0) {
      if (!(usage & GNUTLS_KEY_DIGITAL_SIGNATURE)) {
        return gnutls_assert_val(
          GNUTLS_CERT_SIGNER_CONSTRAINTS_FAILURE);
      }
    }

    for (i = 0; i < vdata_size; i++) {
      if (vdata[i].type == GNUTLS_DT_KEY_PURPOSE_OID) {
        res = _gnutls_check_key_purpose(
          crt, (char *)vdata[i].data, 0);
        if (res == 0)
          return gnutls_assert_val(
            GNUTLS_CERT_SIGNER_CONSTRAINTS_FAILURE);
        break;
      }
    }
  }

  return ret;
}

/**
 * gnutls_x509_crt_verify_data2:
 * @crt: Holds the certificate to verify with
 * @algo: The signature algorithm used
 * @flags: Zero or an OR list of #gnutls_certificate_verify_flags
 * @data: holds the signed data
 * @signature: contains the signature
 *
 * This function will verify the given signed data, using the
 * parameters from the certificate.
 *
 * Returns: In case of a verification failure %GNUTLS_E_PK_SIG_VERIFY_FAILED
 * is returned, %GNUTLS_E_EXPIRED or %GNUTLS_E_NOT_YET_ACTIVATED on expired
 * or not yet activated certificate and zero or positive code on success.
 *
 * Note that since GnuTLS 3.5.6 this function introduces checks in the
 * end certificate (@crt), including time checks and key usage checks.
 *
 * Since: 3.4.0
 **/
int gnutls_x509_crt_verify_data2(gnutls_x509_crt_t crt,
         gnutls_sign_algorithm_t algo,
         unsigned int flags, const gnutls_datum_t *data,
         const gnutls_datum_t *signature)
{
  return gnutls_x509_crt_verify_data3(crt, algo, NULL, 0, data, signature,
              flags);
}

/**
 * gnutls_x509_crt_set_flags:
 * @cert: A type #gnutls_x509_crt_t
 * @flags: flags from the %gnutls_x509_crt_flags
 *
 * This function will set flags for the specified certificate.
 * Currently this is useful for the %GNUTLS_X509_CRT_FLAG_IGNORE_SANITY
 * which allows importing certificates even if they have known issues.
 *
 * Since: 3.6.0
 *
 **/
void gnutls_x509_crt_set_flags(gnutls_x509_crt_t cert, unsigned int flags)
{
  cert->flags = flags;
}

Coverage Report

Created: 2023-11-27 06:16