/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)

 * All rights reserved.

 *

 * This package is an SSL implementation written

 * by Eric Young (eay@cryptsoft.com).

 * The implementation was written so as to conform with Netscapes SSL.

 *

 * This library is free for commercial and non-commercial use as long as

 * the following conditions are aheared to.  The following conditions

 * apply to all code found in this distribution, be it the RC4, RSA,

 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation

 * included with this distribution is covered by the same copyright terms

 * except that the holder is Tim Hudson (tjh@cryptsoft.com).

 *

 * Copyright remains Eric Young's, and as such any Copyright notices in

 * the code are not to be removed.

 * If this package is used in a product, Eric Young should be given attribution

 * as the author of the parts of the library used.

 * This can be in the form of a textual message at program startup or

 * in documentation (online or textual) provided with the package.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. All advertising materials mentioning features or use of this software

 *    must display the following acknowledgement:

 *    "This product includes cryptographic software written by

 *     Eric Young (eay@cryptsoft.com)"

 *    The word 'cryptographic' can be left out if the rouines from the library

 *    being used are not cryptographic related :-).

 * 4. If you include any Windows specific code (or a derivative thereof) from

 *    the apps directory (application code) you must include an acknowledgement:

 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"

 *

 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 *

 * The licence and distribution terms for any publically available version or

 * derivative of this code cannot be changed.  i.e. this code cannot simply be

 * copied and put under another distribution licence

 * [including the GNU Public Licence.] */

#include <openssl/bn.h>

#include <assert.h>

#include <ctype.h>

#include <limits.h>

#include <stdio.h>

#include <openssl/bio.h>

#include <openssl/bytestring.h>

#include <openssl/err.h>

#include <openssl/mem.h>

#include "../fipsmodule/bn/internal.h"

int BN_bn2cbb_padded(CBB *out, size_t len, const BIGNUM *in) {

  uint8_t *ptr;

  return CBB_add_space(out, &ptr, len) && BN_bn2bin_padded(ptr, len, in);

}

static const char hextable[] = "0123456789abcdef";

char *BN_bn2hex(const BIGNUM *bn) {

  int width = bn_minimal_width(bn);

  char *buf = OPENSSL_malloc(1 /* leading '-' */ + 1 /* zero is non-empty */ +

                             width * BN_BYTES * 2 + 1 /* trailing NUL */);

  if (buf == NULL) {

    return NULL;

  }

  char *p = buf;

  if (bn->neg) {

    *(p++) = '-';

  }

  if (BN_is_zero(bn)) {

    *(p++) = '0';

  }

  int z = 0;

  for (int i = width - 1; i >= 0; i--) {

    for (int j = BN_BITS2 - 8; j >= 0; j -= 8) {

      // strip leading zeros

      int v = ((int)(bn->d[i] >> (long)j)) & 0xff;

      if (z || v != 0) {

        *(p++) = hextable[v >> 4];

        *(p++) = hextable[v & 0x0f];

        z = 1;

      }

    }

  }

  *p = '\0';

  return buf;

}

// decode_hex decodes |in_len| bytes of hex data from |in| and updates |bn|.

static int decode_hex(BIGNUM *bn, const char *in, int in_len) {

  if (in_len > INT_MAX/4) {

    OPENSSL_PUT_ERROR(BN, BN_R_BIGNUM_TOO_LONG);

    return 0;

  }

  // |in_len| is the number of hex digits.

  if (!bn_expand(bn, in_len * 4)) {

    return 0;

  }

  int i = 0;

  while (in_len > 0) {

    // Decode one |BN_ULONG| at a time.

    int todo = BN_BYTES * 2;

    if (todo > in_len) {

      todo = in_len;

    }

    BN_ULONG word = 0;

    int j;

    for (j = todo; j > 0; j--) {

      uint8_t hex = 0;

      if (!OPENSSL_fromxdigit(&hex, in[in_len - j])) {

        // This shouldn't happen. The caller checks |OPENSSL_isxdigit|.

        assert(0);

      }

      word = (word << 4) | hex;

    }

    bn->d[i++] = word;

    in_len -= todo;

  }

  assert(i <= bn->dmax);

  bn->width = i;

  return 1;

}

// decode_dec decodes |in_len| bytes of decimal data from |in| and updates |bn|.

static int decode_dec(BIGNUM *bn, const char *in, int in_len) {

  int i, j;

  BN_ULONG l = 0;

  // Decode |BN_DEC_NUM| digits at a time.

  j = BN_DEC_NUM - (in_len % BN_DEC_NUM);

  if (j == BN_DEC_NUM) {

    j = 0;

  }

  l = 0;

  for (i = 0; i < in_len; i++) {

    l *= 10;

    l += in[i] - '0';

    if (++j == BN_DEC_NUM) {

      if (!BN_mul_word(bn, BN_DEC_CONV) ||

          !BN_add_word(bn, l)) {

        return 0;

      }

      l = 0;

      j = 0;

    }

  }

  return 1;

}

typedef int (*decode_func) (BIGNUM *bn, const char *in, int in_len);

typedef int (*char_test_func) (int c);

static int bn_x2bn(BIGNUM **outp, const char *in, decode_func decode, char_test_func want_char) {

  BIGNUM *ret = NULL;

  int neg = 0, i;

  int num;

  if (in == NULL || *in == 0) {

    return 0;

  }

  if (*in == '-') {

    neg = 1;

    in++;

  }

  for (i = 0; want_char((unsigned char)in[i]) && i + neg < INT_MAX; i++) {}

  num = i + neg;

  if (outp == NULL) {

    return num;

  }

  // in is the start of the hex digits, and it is 'i' long

  if (*outp == NULL) {

    ret = BN_new();

    if (ret == NULL) {

      return 0;

    }

  } else {

    ret = *outp;

    BN_zero(ret);

  }

  if (!decode(ret, in, i)) {

    goto err;

  }

  bn_set_minimal_width(ret);

  if (!BN_is_zero(ret)) {

    ret->neg = neg;

  }

  *outp = ret;

  return num;

err:

  if (*outp == NULL) {

    BN_free(ret);

  }

  return 0;

}

int BN_hex2bn(BIGNUM **outp, const char *in) {

  return bn_x2bn(outp, in, decode_hex, OPENSSL_isxdigit);

}

char *BN_bn2dec(const BIGNUM *a) {

  // It is easier to print strings little-endian, so we assemble it in reverse

  // and fix at the end.

  BIGNUM *copy = NULL;

  CBB cbb;

  if (!CBB_init(&cbb, 16) ||

      !CBB_add_u8(&cbb, 0 /* trailing NUL */)) {

    goto err;

  }

  if (BN_is_zero(a)) {

    if (!CBB_add_u8(&cbb, '0')) {

      goto err;

    }

  } else {

    copy = BN_dup(a);

    if (copy == NULL) {

      goto err;

    }

    while (!BN_is_zero(copy)) {

      BN_ULONG word = BN_div_word(copy, BN_DEC_CONV);

      if (word == (BN_ULONG)-1) {

        goto err;

      }

      const int add_leading_zeros = !BN_is_zero(copy);

      for (int i = 0; i < BN_DEC_NUM && (add_leading_zeros || word != 0); i++) {

        if (!CBB_add_u8(&cbb, '0' + word % 10)) {

          goto err;

        }

        word /= 10;

      }

      assert(word == 0);

    }

  }

  if (BN_is_negative(a) &&

      !CBB_add_u8(&cbb, '-')) {

    goto err;

  }

  uint8_t *data;

  size_t len;

  if (!CBB_finish(&cbb, &data, &len)) {

    goto err;

  }

  // Reverse the buffer.

  for (size_t i = 0; i < len/2; i++) {

    uint8_t tmp = data[i];

    data[i] = data[len - 1 - i];

    data[len - 1 - i] = tmp;

  }

  BN_free(copy);

  return (char *)data;

err:

  BN_free(copy);

  CBB_cleanup(&cbb);

  return NULL;

}

int BN_dec2bn(BIGNUM **outp, const char *in) {

  return bn_x2bn(outp, in, decode_dec, OPENSSL_isdigit);

}

int BN_asc2bn(BIGNUM **outp, const char *in) {

  const char *const orig_in = in;

  if (*in == '-') {

    in++;

  }

  if (in[0] == '0' && (in[1] == 'X' || in[1] == 'x')) {

    if (!BN_hex2bn(outp, in+2)) {

      return 0;

    }

  } else {

    if (!BN_dec2bn(outp, in)) {

      return 0;

    }

  }

  if (*orig_in == '-' && !BN_is_zero(*outp)) {

    (*outp)->neg = 1;

  }

  return 1;

}

int BN_print(BIO *bp, const BIGNUM *a) {

  int i, j, v, z = 0;

  int ret = 0;

  if (a->neg && BIO_write(bp, "-", 1) != 1) {

    goto end;

  }

  if (BN_is_zero(a) && BIO_write(bp, "0", 1) != 1) {

    goto end;

  }

  for (i = bn_minimal_width(a) - 1; i >= 0; i--) {

    for (j = BN_BITS2 - 4; j >= 0; j -= 4) {

      // strip leading zeros

      v = ((int)(a->d[i] >> (long)j)) & 0x0f;

      if (z || v != 0) {

        if (BIO_write(bp, &hextable[v], 1) != 1) {

          goto end;

        }

        z = 1;

      }

    }

  }

  ret = 1;

end:

  return ret;

}

int BN_print_fp(FILE *fp, const BIGNUM *a) {

  BIO *b = BIO_new_fp(fp, BIO_NOCLOSE);

  if (b == NULL) {

    return 0;

  }

  int ret = BN_print(b, a);

  BIO_free(b);

  return ret;

}

size_t BN_bn2mpi(const BIGNUM *in, uint8_t *out) {

  const size_t bits = BN_num_bits(in);

  const size_t bytes = (bits + 7) / 8;

  // If the number of bits is a multiple of 8, i.e. if the MSB is set,

  // prefix with a zero byte.

  int extend = 0;

  if (bytes != 0 && (bits & 0x07) == 0) {

    extend = 1;

  }

  const size_t len = bytes + extend;

  if (len < bytes ||

      4 + len < len ||

      (len & 0xffffffff) != len) {

    // If we cannot represent the number then we emit zero as the interface

    // doesn't allow an error to be signalled.

    if (out) {

      OPENSSL_memset(out, 0, 4);

    }

    return 4;

  }

  if (out == NULL) {

    return 4 + len;

  }

  out[0] = len >> 24;

  out[1] = len >> 16;

  out[2] = len >> 8;

  out[3] = len;

  if (extend) {

    out[4] = 0;

  }

  BN_bn2bin(in, out + 4 + extend);

  if (in->neg && len > 0) {

    out[4] |= 0x80;

  }

  return len + 4;

}

BIGNUM *BN_mpi2bn(const uint8_t *in, size_t len, BIGNUM *out) {

  if (len < 4) {

    OPENSSL_PUT_ERROR(BN, BN_R_BAD_ENCODING);

    return NULL;

  }

  const size_t in_len = ((size_t)in[0] << 24) |

                        ((size_t)in[1] << 16) |

                        ((size_t)in[2] << 8) |

                        ((size_t)in[3]);

  if (in_len != len - 4) {

    OPENSSL_PUT_ERROR(BN, BN_R_BAD_ENCODING);

    return NULL;

  }

  int out_is_alloced = 0;

  if (out == NULL) {

    out = BN_new();

    if (out == NULL) {

      return NULL;

    }

    out_is_alloced = 1;

  }

  if (in_len == 0) {

    BN_zero(out);

    return out;

  }

  in += 4;

  if (BN_bin2bn(in, in_len, out) == NULL) {

    if (out_is_alloced) {

      BN_free(out);

    }

    return NULL;

  }

  out->neg = ((*in) & 0x80) != 0;

  if (out->neg) {

    BN_clear_bit(out, BN_num_bits(out) - 1);

  }

  return out;

}

int BN_bn2binpad(const BIGNUM *in, uint8_t *out, int len) {

  if (len < 0 ||

      !BN_bn2bin_padded(out, (size_t)len, in)) {

    return -1;

  }

  return len;

}

int BN_bn2lebinpad(const BIGNUM *in, uint8_t *out, int len) {

  if (len < 0 ||

      !BN_bn2le_padded(out, (size_t)len, in)) {

    return -1;

  }

  return len;

}