corrected copyright notices

[gnutls.git] / lib / x509 / crl.c

/*
 * Copyright (C) 2003-2012 Free Software Foundation, Inc.
 *
 * Author: Nikos Mavrogiannopoulos
 *
 * This file is part of GnuTLS.
 *
 * The GnuTLS is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 3 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 <http://www.gnu.org/licenses/>
 *
 */

#include <gnutls_int.h>
#include <libtasn1.h>

#include <gnutls_datum.h>
#include <gnutls_global.h>
#include <gnutls_errors.h>
#include <common.h>
#include <x509_b64.h>
#include <x509_int.h>
#include <gnutls_x509.h>

/**
 * gnutls_x509_crl_init:
 * @crl: The structure to be initialized
 *
 * This function will initialize a CRL structure. CRL stands for
 * Certificate Revocation List. A revocation list usually contains
 * lists of certificate serial numbers that have been revoked by an
 * Authority. The revocation lists are always signed with the
 * authority's private key.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int
gnutls_x509_crl_init (gnutls_x509_crl_t * crl)
{
  *crl = gnutls_calloc (1, sizeof (gnutls_x509_crl_int));

  if (*crl)
    {
      int result = asn1_create_element (_gnutls_get_pkix (),
                                        "PKIX1.CertificateList",
                                        &(*crl)->crl);
      if (result != ASN1_SUCCESS)
        {
          gnutls_assert ();
          gnutls_free (*crl);
          return _gnutls_asn2err (result);
        }
      return 0;                 /* success */
    }
  return GNUTLS_E_MEMORY_ERROR;
}

/**
 * gnutls_x509_crl_deinit:
 * @crl: The structure to be initialized
 *
 * This function will deinitialize a CRL structure.
 **/
void
gnutls_x509_crl_deinit (gnutls_x509_crl_t crl)
{
  if (!crl)
    return;

  if (crl->crl)
    asn1_delete_structure (&crl->crl);

  gnutls_free (crl);
}

/**
 * gnutls_x509_crl_import:
 * @crl: The structure to store the parsed CRL.
 * @data: The DER or PEM encoded CRL.
 * @format: One of DER or PEM
 *
 * This function will convert the given DER or PEM encoded CRL
 * to the native #gnutls_x509_crl_t format. The output will be stored in 'crl'.
 *
 * If the CRL is PEM encoded it should have a header of "X509 CRL".
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int
gnutls_x509_crl_import (gnutls_x509_crl_t crl,
                        const gnutls_datum_t * data,
                        gnutls_x509_crt_fmt_t format)
{
  int result = 0, need_free = 0;
  gnutls_datum_t _data;

  _data.data = data->data;
  _data.size = data->size;

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

  /* If the CRL is in PEM format then decode it
   */
  if (format == GNUTLS_X509_FMT_PEM)
    {
      result = _gnutls_fbase64_decode (PEM_CRL, data->data, data->size, &_data);

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

      need_free = 1;
    }


  result = asn1_der_decoding (&crl->crl, _data.data, _data.size, NULL);
  if (result != ASN1_SUCCESS)
    {
      result = _gnutls_asn2err (result);
      gnutls_assert ();
      goto cleanup;
    }

  if (need_free)
    _gnutls_free_datum (&_data);

  return 0;

cleanup:
  if (need_free)
    _gnutls_free_datum (&_data);
  return result;
}


/**
 * gnutls_x509_crl_get_issuer_dn:
 * @crl: should contain a gnutls_x509_crl_t structure
 * @buf: a pointer to a structure to hold the peer's name (may be null)
 * @sizeof_buf: initially holds the size of @buf
 *
 * This function will copy the name of the CRL 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.
 *
 * Returns: %GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is
 * not long enough, and in that case the sizeof_buf will be updated
 * with the required size, and 0 on success.
 *
 **/
int
gnutls_x509_crl_get_issuer_dn (const gnutls_x509_crl_t crl, char *buf,
                               size_t * sizeof_buf)
{
  if (crl == NULL)
    {
      gnutls_assert ();
      return GNUTLS_E_INVALID_REQUEST;
    }

  return _gnutls_x509_parse_dn (crl->crl,
                                "tbsCertList.issuer.rdnSequence",
                                buf, sizeof_buf);
}

/**
 * gnutls_x509_crl_get_issuer_dn_by_oid:
 * @crl: should contain a gnutls_x509_crl_t structure
 * @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 peer's name (may be null)
 * @sizeof_buf: initially holds the size of @buf
 *
 * This function will extract the part of the name of the CRL issuer
 * specified by the given OID. The output will be encoded as described
 * in RFC4514. The output string will be 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.
 *
 * Returns: %GNUTLS_E_SHORT_MEMORY_BUFFER if the provided buffer is
 * not long enough, and in that case the sizeof_buf will be updated
 * with the required size, and 0 on success.
 **/
int
gnutls_x509_crl_get_issuer_dn_by_oid (gnutls_x509_crl_t crl,
                                      const char *oid, int indx,
                                      unsigned int raw_flag, void *buf,
                                      size_t * sizeof_buf)
{
gnutls_datum_t td;
int ret;

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

  ret = _gnutls_x509_parse_dn_oid (crl->crl,
                                    "tbsCertList.issuer.rdnSequence",
                                    oid, indx, raw_flag, &td);
  if (ret < 0)
    return gnutls_assert_val(ret);
  
  return _gnutls_strdatum_to_buf (&td, buf, sizeof_buf);
}


/**
 * gnutls_x509_crl_get_dn_oid:
 * @crl: should contain a gnutls_x509_crl_t structure
 * @indx: Specifies which DN OID to send. Use (0) to get the first one.
 * @oid: a pointer to a structure to hold the name (may be null)
 * @sizeof_oid: initially holds the size of 'oid'
 *
 * This function will extract the requested OID of the name of the CRL
 * issuer, specified by the given index.
 *
 * If oid 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 sizeof_oid will be updated
 * with the required size.  On success 0 is returned.
 **/
int
gnutls_x509_crl_get_dn_oid (gnutls_x509_crl_t crl,
                            int indx, void *oid, size_t * sizeof_oid)
{
  if (crl == NULL)
    {
      gnutls_assert ();
      return GNUTLS_E_INVALID_REQUEST;
    }

  return _gnutls_x509_get_dn_oid (crl->crl,
                                  "tbsCertList.issuer.rdnSequence", indx,
                                  oid, sizeof_oid);
}


/**
 * gnutls_x509_crl_get_signature_algorithm:
 * @crl: should contain a #gnutls_x509_crl_t structure
 *
 * This function will return a value of the #gnutls_sign_algorithm_t
 * enumeration that is the signature algorithm.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value.
 **/
int
gnutls_x509_crl_get_signature_algorithm (gnutls_x509_crl_t crl)
{
  int result;
  gnutls_datum_t sa;

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

  /* Read the signature algorithm. Note that parameters are not
   * read. They will be read from the issuer's certificate if needed.
   */

  result =
    _gnutls_x509_read_value (crl->crl, "signatureAlgorithm.algorithm",
                             &sa);

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

  result = _gnutls_x509_oid2sign_algorithm ((const char *) sa.data);

  _gnutls_free_datum (&sa);

  return result;
}

/**
 * gnutls_x509_crl_get_signature:
 * @crl: should contain a gnutls_x509_crl_t structure
 * @sig: a pointer where the signature part will be copied (may be null).
 * @sizeof_sig: initially holds the size of @sig
 *
 * This function will extract the signature field of a CRL.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value. and a negative error code on error.
 **/
int
gnutls_x509_crl_get_signature (gnutls_x509_crl_t crl,
                               char *sig, size_t * sizeof_sig)
{
  int result;
  unsigned int bits;
  int len;

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

  len = 0;
  result = asn1_read_value (crl->crl, "signature", NULL, &len);

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

  bits = len;
  if (bits % 8 != 0)
    {
      gnutls_assert ();
      return GNUTLS_E_CERTIFICATE_ERROR;
    }

  len = bits / 8;

  if (*sizeof_sig < (unsigned)len)
    {
      *sizeof_sig = bits / 8;
      return GNUTLS_E_SHORT_MEMORY_BUFFER;
    }

  result = asn1_read_value (crl->crl, "signature", sig, &len);
  if (result != ASN1_SUCCESS)
    {
      gnutls_assert ();
      return _gnutls_asn2err (result);
    }

  return 0;
}

/**
 * gnutls_x509_crl_get_version:
 * @crl: should contain a #gnutls_x509_crl_t structure
 *
 * This function will return the version of the specified CRL.
 *
 * Returns: The version number, or a negative error code on error.
 **/
int
gnutls_x509_crl_get_version (gnutls_x509_crl_t crl)
{
  uint8_t version[8];
  int len, result;

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

  len = sizeof (version);
  if ((result =
       asn1_read_value (crl->crl, "tbsCertList.version", version,
                        &len)) != ASN1_SUCCESS)
    {
      gnutls_assert ();
      return _gnutls_asn2err (result);
    }

  return (int) version[0] + 1;
}

/**
 * gnutls_x509_crl_get_this_update:
 * @crl: should contain a #gnutls_x509_crl_t structure
 *
 * This function will return the time this CRL was issued.
 *
 * Returns: when the CRL was issued, or (time_t)-1 on error.
 **/
time_t
gnutls_x509_crl_get_this_update (gnutls_x509_crl_t crl)
{
  if (crl == NULL)
    {
      gnutls_assert ();
      return (time_t) - 1;
    }

  return _gnutls_x509_get_time (crl->crl, "tbsCertList.thisUpdate", 0);
}

/**
 * gnutls_x509_crl_get_next_update:
 * @crl: should contain a #gnutls_x509_crl_t structure
 *
 * This function will return the time the next CRL will be issued.
 * This field is optional in a CRL so it might be normal to get an
 * error instead.
 *
 * Returns: when the next CRL will be issued, or (time_t)-1 on error.
 **/
time_t
gnutls_x509_crl_get_next_update (gnutls_x509_crl_t crl)
{
  if (crl == NULL)
    {
      gnutls_assert ();
      return (time_t) - 1;
    }

  return _gnutls_x509_get_time (crl->crl, "tbsCertList.nextUpdate", 0);
}

/**
 * gnutls_x509_crl_get_crt_count:
 * @crl: should contain a #gnutls_x509_crl_t structure
 *
 * This function will return the number of revoked certificates in the
 * given CRL.
 *
 * Returns: number of certificates, a negative error code on failure.
 **/
int
gnutls_x509_crl_get_crt_count (gnutls_x509_crl_t crl)
{

  int count, result;

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

  result =
    asn1_number_of_elements (crl->crl,
                             "tbsCertList.revokedCertificates", &count);

  if (result != ASN1_SUCCESS)
    {
      gnutls_assert ();
      return 0;                 /* no certificates */
    }

  return count;
}

/**
 * gnutls_x509_crl_get_crt_serial:
 * @crl: should contain a #gnutls_x509_crl_t structure
 * @indx: the index of the certificate to extract (starting from 0)
 * @serial: where the serial number will be copied
 * @serial_size: initially holds the size of serial
 * @t: if non null, will hold the time this certificate was revoked
 *
 * This function will retrieve the serial number of the specified, by
 * the index, revoked certificate.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value. and a negative error code on error.
 **/
int
gnutls_x509_crl_get_crt_serial (gnutls_x509_crl_t crl, int indx,
                                unsigned char *serial,
                                size_t * serial_size, time_t * t)
{

  int result, _serial_size;
  char serial_name[ASN1_MAX_NAME_SIZE];
  char date_name[ASN1_MAX_NAME_SIZE];

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

  snprintf (serial_name, sizeof (serial_name),
            "tbsCertList.revokedCertificates.?%u.userCertificate", indx + 1);
  snprintf (date_name, sizeof (date_name),
            "tbsCertList.revokedCertificates.?%u.revocationDate", indx + 1);

  _serial_size = *serial_size;
  result = asn1_read_value (crl->crl, serial_name, serial, &_serial_size);

  *serial_size = _serial_size;
  if (result != ASN1_SUCCESS)
    {
      gnutls_assert ();
      if (result == ASN1_ELEMENT_NOT_FOUND)
        return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
      return _gnutls_asn2err (result);
    }

  if (t)
    {
      *t = _gnutls_x509_get_time (crl->crl, date_name, 0);
    }

  return 0;
}

/**
 * gnutls_x509_crl_get_raw_issuer_dn:
 * @crl: should contain a gnutls_x509_crl_t structure
 * @dn: will hold the starting point of the DN
 *
 * This function will return a pointer to the DER encoded DN structure
 * and the length.
 *
 * Returns: a negative error code on error, and (0) on success.
 *
 * Since: 2.12.0
 **/
int
gnutls_x509_crl_get_raw_issuer_dn (gnutls_x509_crl_t crl,
                                   gnutls_datum_t * dn)
{
  ASN1_TYPE c2 = ASN1_TYPE_EMPTY;
  int result, len1;
  int start1, end1;
  gnutls_datum_t crl_signed_data;

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

  /* get the issuer of 'crl'
   */
  if ((result =
       asn1_create_element (_gnutls_get_pkix (), "PKIX1.TBSCertList",
                            &c2)) != ASN1_SUCCESS)
    {
      gnutls_assert ();
      return _gnutls_asn2err (result);
    }

  result =
    _gnutls_x509_get_signed_data (crl->crl, "tbsCertList", &crl_signed_data);
  if (result < 0)
    {
      gnutls_assert ();
      goto cleanup;
    }

  result =
    asn1_der_decoding (&c2, crl_signed_data.data, crl_signed_data.size, NULL);
  if (result != ASN1_SUCCESS)
    {
      /* couldn't decode DER */
      gnutls_assert ();
      asn1_delete_structure (&c2);
      result = _gnutls_asn2err (result);
      goto cleanup;
    }

  result =
    asn1_der_decoding_startEnd (c2, crl_signed_data.data,
                                crl_signed_data.size, "issuer",
                                &start1, &end1);

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

  len1 = end1 - start1 + 1;

  _gnutls_set_datum (dn, &crl_signed_data.data[start1], len1);

  result = 0;

cleanup:
  asn1_delete_structure (&c2);
  _gnutls_free_datum (&crl_signed_data);
  return result;
}

/**
 * gnutls_x509_crl_export:
 * @crl: Holds the revocation list
 * @format: the format of output params. One of PEM or DER.
 * @output_data: will contain a private key 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 revocation list to DER or PEM format.
 *
 * If the buffer provided is not long enough to hold the output, then
 * %GNUTLS_E_SHORT_MEMORY_BUFFER will be returned.
 *
 * If the structure is PEM encoded, it will have a header
 * of "BEGIN X509 CRL".
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value. and a negative error code on failure.
 **/
int
gnutls_x509_crl_export (gnutls_x509_crl_t crl,
                        gnutls_x509_crt_fmt_t format, void *output_data,
                        size_t * output_data_size)
{
  if (crl == NULL)
    {
      gnutls_assert ();
      return GNUTLS_E_INVALID_REQUEST;
    }

  return _gnutls_x509_export_int (crl->crl, format, PEM_CRL,
                                  output_data, output_data_size);
}

/**
 * gnutls_x509_crl_export2:
 * @crl: Holds the revocation list
 * @format: the format of output params. One of PEM or DER.
 * @out: will contain a private key PEM or DER encoded
 *
 * This function will export the revocation list 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 X509 CRL".
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error value. and a negative error code on failure.
 *
 * Since 3.1.3
 **/
int
gnutls_x509_crl_export2 (gnutls_x509_crl_t crl,
                        gnutls_x509_crt_fmt_t format, gnutls_datum_t *out)
{
  if (crl == NULL)
    {
      gnutls_assert ();
      return GNUTLS_E_INVALID_REQUEST;
    }

  return _gnutls_x509_export_int2 (crl->crl, format, PEM_CRL, out);
}

/*-
 * _gnutls_x509_crl_cpy - This function copies a gnutls_x509_crl_t structure
 * @dest: The structure where to copy
 * @src: The structure to be copied
 *
 * 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_crl_cpy (gnutls_x509_crl_t dest, gnutls_x509_crl_t src)
{
  int ret;
  gnutls_datum_t tmp;

  ret = gnutls_x509_crl_export2 (src, GNUTLS_X509_FMT_DER, &tmp);
  if (ret < 0)
    return gnutls_assert_val(ret);

  ret = gnutls_x509_crl_import (dest, &tmp, GNUTLS_X509_FMT_DER);

  gnutls_free (tmp.data);

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

  return 0;

}

static int
_get_authority_key_id (gnutls_x509_crl_t cert, ASN1_TYPE *c2,
                       unsigned int *critical)
{
  int ret;
  gnutls_datum_t id;
  
  *c2 = ASN1_TYPE_EMPTY;

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

  if ((ret =
       _gnutls_x509_crl_get_extension (cert, "2.5.29.35", 0, &id,
                                       critical)) < 0)
    {
      return gnutls_assert_val(ret);
    }

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

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

  ret = asn1_der_decoding (c2, id.data, id.size, NULL);
  _gnutls_free_datum (&id);

  if (ret != ASN1_SUCCESS)
    {
      gnutls_assert ();
      asn1_delete_structure (c2);
      return _gnutls_asn2err (ret);
    }

  return 0;
}

/**
 * gnutls_x509_crl_get_authority_key_gn_serial:
 * @crl: should contain a #gnutls_x509_crl_t structure
 * @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: Returns 0 on success, or an error code.
 *
 * Since: 3.0
 **/
int
gnutls_x509_crl_get_authority_key_gn_serial (gnutls_x509_crl_t crl,
                                             unsigned int seq,
                                             void *alt,
                                             size_t * alt_size,
                                             unsigned int *alt_type,
                                             void* serial,
                                             size_t *serial_size,
                                             unsigned int *critical)
{
  int ret, result, len;
  ASN1_TYPE c2;

  ret = _get_authority_key_id(crl, &c2, critical);
  if (ret < 0)
    return gnutls_assert_val(ret);

  ret =
    _gnutls_parse_general_name (c2, "authorityCertIssuer", seq, alt, alt_size, alt_type,
                                0);
  if (ret < 0)
    {
      ret = gnutls_assert_val(ret);
      goto fail;
    }

  if (serial)
    {
      len = *serial_size;
      result = asn1_read_value (c2, "authorityCertSerialNumber", serial, &len);
      
      *serial_size = len;
      
      if (result < 0)
        {
          ret = _gnutls_asn2err(result);
          goto fail;
        }
      
    }
   
  ret = 0;

fail:
  asn1_delete_structure (&c2);
  
  return ret;
}


/**
 * gnutls_x509_crl_get_authority_key_id:
 * @crl: should contain a #gnutls_x509_crl_t structure
 * @id: The place where the identifier will be copied
 * @id_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 CRL 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_crl_get_authority_key_gn_serial() may be used.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code in case of an error.
 *
 * Since: 2.8.0
 **/
int
gnutls_x509_crl_get_authority_key_id (gnutls_x509_crl_t crl, void *id,
                                      size_t * id_size,
                                      unsigned int *critical)
{
  int result, len, ret;
  ASN1_TYPE c2;

  ret = _get_authority_key_id(crl, &c2, critical);
  if (ret < 0)
    return gnutls_assert_val(ret);

  len = *id_size;
  result = asn1_read_value (c2, "keyIdentifier", id, &len);

  *id_size = len;
  asn1_delete_structure (&c2);

  if (result == ASN1_VALUE_NOT_FOUND || result == ASN1_ELEMENT_NOT_FOUND)
    return gnutls_assert_val(GNUTLS_E_X509_UNSUPPORTED_EXTENSION);

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

  return 0;
}

/**
 * gnutls_x509_crl_get_number:
 * @crl: should contain a #gnutls_x509_crl_t structure
 * @ret: The place where the number 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 CRL number extension.  This is
 * obtained by the CRL Number extension field (2.5.29.20).
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code in case of an error.
 *
 * Since: 2.8.0
 **/
int
gnutls_x509_crl_get_number (gnutls_x509_crl_t crl, void *ret,
                            size_t * ret_size, unsigned int *critical)
{
  int result;
  gnutls_datum_t id;

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


  if (ret)
    memset (ret, 0, *ret_size);
  else
    *ret_size = 0;

  if ((result =
       _gnutls_x509_crl_get_extension (crl, "2.5.29.20", 0, &id,
                                       critical)) < 0)
    {
      return result;
    }

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

  result = _gnutls_x509_ext_extract_number (ret, ret_size, id.data, id.size);

  _gnutls_free_datum (&id);

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

  return 0;
}

/**
 * gnutls_x509_crl_get_extension_oid:
 * @crl: should contain a #gnutls_x509_crl_t structure
 * @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)
 * @sizeof_oid: initially holds the size of @oid
 *
 * This function will return the requested extension OID in the CRL.
 * The extension OID will be stored as a string in the provided
 * buffer.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code in case of an error.  If your have reached the
 *   last extension available %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
 *   will be returned.
 *
 * Since: 2.8.0
 **/
int
gnutls_x509_crl_get_extension_oid (gnutls_x509_crl_t crl, int indx,
                                   void *oid, size_t * sizeof_oid)
{
  int result;

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

  result = _gnutls_x509_crl_get_extension_oid (crl, indx, oid, sizeof_oid);
  if (result < 0)
    {
      return result;
    }

  return 0;

}

/**
 * gnutls_x509_crl_get_extension_info:
 * @crl: should contain a #gnutls_x509_crl_t structure
 * @indx: Specifies which extension OID to send, use (0) to get the first one.
 * @oid: a pointer to a structure to hold the OID
 * @sizeof_oid: 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 CRL,
 * and the critical flag for it.  The extension OID will be stored as
 * a string in the provided buffer.  Use
 * gnutls_x509_crl_get_extension_data() to extract the data.
 *
 * If the buffer provided is not long enough to hold the output, then
 * *@sizeof_oid is updated and %GNUTLS_E_SHORT_MEMORY_BUFFER will be
 * returned.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
 *   negative error code in case of an error.  If your have reached the
 *   last extension available %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
 *   will be returned.
 *
 * Since: 2.8.0
 **/
int
gnutls_x509_crl_get_extension_info (gnutls_x509_crl_t crl, int indx,
                                    void *oid, size_t * sizeof_oid,
                                    unsigned int *critical)
{
  int result;
  char str_critical[10];
  char name[ASN1_MAX_NAME_SIZE];
  int len;

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

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

  len = *sizeof_oid;
  result = asn1_read_value (crl->crl, name, oid, &len);
  *sizeof_oid = 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);
    }

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

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

  return 0;

}

/**
 * gnutls_x509_crl_get_extension_data:
 * @crl: should contain a #gnutls_x509_crl_t structure
 * @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 @oid
 *
 * This function will return the requested extension data in the CRL.
 * The extension data will be stored as a string in the provided
 * buffer.
 *
 * Use gnutls_x509_crl_get_extension_info() to extract the OID and
 * critical flag.  Use gnutls_x509_crl_get_extension_info() 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 in case of an error.  If your have reached the
 *   last extension available %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE
 *   will be returned.
 *
 * Since: 2.8.0
 **/
int
gnutls_x509_crl_get_extension_data (gnutls_x509_crl_t crl, int indx,
                                    void *data, size_t * sizeof_data)
{
  int result, len;
  char name[ASN1_MAX_NAME_SIZE];

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

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

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

  if (result == ASN1_ELEMENT_NOT_FOUND)
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
  else if (result < 0)
    {
      gnutls_assert ();
      return _gnutls_asn2err (result);
    }

  return 0;
}

/**
 * gnutls_x509_crl_list_import2:
 * @crls: The structures to store the parsed crl list. Must not be initialized.
 * @size: It will contain the size of the list.
 * @data: The PEM encoded CRL.
 * @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 CRL list
 * to the native gnutls_x509_crl_t format. The output will be stored
 * in @crls.  They will be automatically initialized.
 *
 * If the Certificate is PEM encoded it should have a header of "X509
 * CRL".
 *
 * Returns: the number of certificates read or a negative error value.
 *
 * Since: 3.0
 **/
int
gnutls_x509_crl_list_import2 (gnutls_x509_crl_t ** crls,
                             unsigned int * size,
                             const gnutls_datum_t * data,
                             gnutls_x509_crt_fmt_t format, unsigned int flags)
{
unsigned int init = 1024;
int ret;

  *crls = gnutls_malloc(sizeof(gnutls_x509_crl_t)*init);
  if (*crls == NULL)
    {
      gnutls_assert();
      return GNUTLS_E_MEMORY_ERROR;
    }

  ret = gnutls_x509_crl_list_import(*crls, &init, data, format, GNUTLS_X509_CRT_LIST_IMPORT_FAIL_IF_EXCEED);
  if (ret == GNUTLS_E_SHORT_MEMORY_BUFFER)
    {
      *crls = gnutls_realloc_fast(*crls, sizeof(gnutls_x509_crl_t)*init);
      if (*crls == NULL)
        {
          gnutls_assert();
          return GNUTLS_E_MEMORY_ERROR;
        }
      
      ret = gnutls_x509_crl_list_import(*crls, &init, data, format, flags);
    }

  if (ret < 0)
    {
      gnutls_free(*crls);
      *crls = NULL;
      return ret;
    }

  *size = init;
  return 0;
}

/**
 * gnutls_x509_crl_list_import:
 * @crls: The structures to store the parsed CRLs. Must not be initialized.
 * @crl_max: Initially must hold the maximum number of crls. It will be updated with the number of crls available.
 * @data: The PEM encoded CRLs
 * @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 CRL list
 * to the native gnutls_x509_crl_t format. The output will be stored
 * in @crls.  They will be automatically initialized.
 *
 * If the Certificate is PEM encoded it should have a header of "X509 CRL".
 *
 * Returns: the number of certificates read or a negative error value.
 *
 * Since: 3.0
 **/
int
gnutls_x509_crl_list_import (gnutls_x509_crl_t * crls,
                             unsigned int *crl_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;

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

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

      ret = gnutls_x509_crl_init (&crls[0]);
      if (ret < 0)
        {
          gnutls_assert ();
          goto error;
        }

      ret = gnutls_x509_crl_import (crls[0], data, format);
      if (ret < 0)
        {
          gnutls_assert ();
          goto error;
        }

      *crl_max = 1;
      return 1;
    }

  /* move to the certificate
   */
  ptr = memmem (data->data, data->size,
                PEM_CRL_SEP, sizeof (PEM_CRL_SEP) - 1);
  if (ptr == NULL)
    {
      gnutls_assert ();
      return GNUTLS_E_BASE64_DECODING_ERROR;
    }

  count = 0;

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

      if (!nocopy)
        {
          ret = gnutls_x509_crl_init (&crls[count]);
          if (ret < 0)
            {
              gnutls_assert ();
              goto error;
            }

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

          ret =
            gnutls_x509_crl_import (crls[count], &tmp, GNUTLS_X509_FMT_PEM);
          if (ret < 0)
            {
              gnutls_assert ();
              goto error;
            }
        }

      /* 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)
        {
          ptr = memmem (ptr, size, PEM_CRL_SEP, sizeof (PEM_CRL_SEP) - 1);
        }
      else
        ptr = NULL;

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

  *crl_max = count;

  if (nocopy == 0)
    return count;
  else
    return GNUTLS_E_SHORT_MEMORY_BUFFER;

error:
  for (j = 0; j < count; j++)
    gnutls_x509_crl_deinit (crls[j]);
  return ret;
}