/* Copyright (c) 2015, Google Inc.

 *

 * Permission to use, copy, modify, and/or distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY

 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION

 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN

 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */

#include <openssl/bn.h>

#include <openssl/bytestring.h>

#include <openssl/err.h>

int BN_parse_asn1_unsigned(CBS *cbs, BIGNUM *ret) {

  CBS child;

  int is_negative;

  if (!CBS_get_asn1(cbs, &child, CBS_ASN1_INTEGER) ||

      !CBS_is_valid_asn1_integer(&child, &is_negative)) {

    OPENSSL_PUT_ERROR(BN, BN_R_BAD_ENCODING);

    return 0;

  }

  if (is_negative) {

    OPENSSL_PUT_ERROR(BN, BN_R_NEGATIVE_NUMBER);

    return 0;

  }

  return BN_bin2bn(CBS_data(&child), CBS_len(&child), ret) != NULL;

}

int BN_marshal_asn1(CBB *cbb, const BIGNUM *bn) {

  // Negative numbers are unsupported.

  if (BN_is_negative(bn)) {

    OPENSSL_PUT_ERROR(BN, BN_R_NEGATIVE_NUMBER);

    return 0;

  }

  CBB child;

  if (!CBB_add_asn1(cbb, &child, CBS_ASN1_INTEGER) ||

      // The number must be padded with a leading zero if the high bit would

      // otherwise be set or if |bn| is zero.

      (BN_num_bits(bn) % 8 == 0 && !CBB_add_u8(&child, 0x00)) ||

      !BN_bn2cbb_padded(&child, BN_num_bytes(bn), bn) ||

      !CBB_flush(cbb)) {

    OPENSSL_PUT_ERROR(BN, BN_R_ENCODE_ERROR);

    return 0;

  }

  return 1;

}