/* $OpenBSD: a_int.c,v 1.44 2022/07/13 20:07:44 jsing Exp $ */

/* 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 <limits.h>

#include <stdio.h>

#include <string.h>

#include <openssl/asn1.h>

#include <openssl/asn1t.h>

#include <openssl/bn.h>

#include <openssl/buffer.h>

#include <openssl/err.h>

#include "bytestring.h"

const ASN1_ITEM ASN1_INTEGER_it = {

  .itype = ASN1_ITYPE_PRIMITIVE,

  .utype = V_ASN1_INTEGER,

  .sname = "ASN1_INTEGER",

};

ASN1_INTEGER *

ASN1_INTEGER_new(void)

{

  return (ASN1_INTEGER *)ASN1_item_new(&ASN1_INTEGER_it);

}

static void

asn1_aint_clear(ASN1_INTEGER *aint)

{

  freezero(aint->data, aint->length);

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

  aint->type = V_ASN1_INTEGER;

}

void

ASN1_INTEGER_free(ASN1_INTEGER *a)

{

  ASN1_item_free((ASN1_VALUE *)a, &ASN1_INTEGER_it);

}

static int

ASN1_INTEGER_valid(const ASN1_INTEGER *a)

{

  return (a != NULL && a->length >= 0);

}

ASN1_INTEGER *

ASN1_INTEGER_dup(const ASN1_INTEGER *x)

{

  if (!ASN1_INTEGER_valid(x))

    return NULL;

  return ASN1_STRING_dup(x);

}

int

ASN1_INTEGER_cmp(const ASN1_INTEGER *a, const ASN1_INTEGER *b)

{

  int ret = 1;

  /* Compare sign, then content. */

  if ((a->type & V_ASN1_NEG) == (b->type & V_ASN1_NEG))

    ret = ASN1_STRING_cmp(a, b);

  if ((a->type & V_ASN1_NEG) != 0)

    return -ret;

  return ret;

}

int

asn1_aint_get_uint64(CBS *cbs, uint64_t *out_val)

{

  uint64_t val = 0;

  uint8_t u8;

  *out_val = 0;

  while (CBS_len(cbs) > 0) {

    if (!CBS_get_u8(cbs, &u8))

      return 0;

    if (val > (UINT64_MAX >> 8)) {

      ASN1error(ASN1_R_TOO_LARGE);

      return 0;

    }

    val = val << 8 | u8;

  }

  *out_val = val;

  return 1;

}

int

asn1_aint_set_uint64(uint64_t val, uint8_t **out_data, int *out_len)

{

  uint8_t *data = NULL;

  size_t data_len = 0;

  int started = 0;

  uint8_t u8;

  CBB cbb;

  int i;

  int ret = 0;

  if (!CBB_init(&cbb, sizeof(long)))

    goto err;

  if (out_data == NULL || out_len == NULL)

    goto err;

  if (*out_data != NULL || *out_len != 0)

    goto err;

  for (i = sizeof(uint64_t) - 1; i >= 0; i--) {

    u8 = (val >> (i * 8)) & 0xff;

    if (!started && i != 0 && u8 == 0)

      continue;

    if (!CBB_add_u8(&cbb, u8))

      goto err;

    started = 1;

  }

  if (!CBB_finish(&cbb, &data, &data_len))

    goto err;

  if (data_len > INT_MAX)

    goto err;

  *out_data = data;

  *out_len = (int)data_len;

  data = NULL;

  ret = 1;

 err:

  CBB_cleanup(&cbb);

  freezero(data, data_len);

  return ret;

}

int

asn1_aint_get_int64(CBS *cbs, int negative, int64_t *out_val)

{

  uint64_t val;

  if (!asn1_aint_get_uint64(cbs, &val))

    return 0;

  if (negative) {

    if (val > (uint64_t)INT64_MIN) {

      ASN1error(ASN1_R_TOO_SMALL);

      return 0;

    }

    *out_val = (int64_t)-val;

  } else {

    if (val > (uint64_t)INT64_MAX) {

      ASN1error(ASN1_R_TOO_LARGE);

      return 0;

    }

    *out_val = (int64_t)val;

  }

  return 1;

}

int

ASN1_INTEGER_get_uint64(uint64_t *out_val, const ASN1_INTEGER *aint)

{

  uint64_t val;

  CBS cbs;

  *out_val = 0;

  if (aint == NULL || aint->length < 0)

    return 0;

  if (aint->type == V_ASN1_NEG_INTEGER) {

    ASN1error(ASN1_R_ILLEGAL_NEGATIVE_VALUE);

    return 0;

  }

  if (aint->type != V_ASN1_INTEGER) {

    ASN1error(ASN1_R_WRONG_INTEGER_TYPE);

    return 0;

  }

  CBS_init(&cbs, aint->data, aint->length);

  if (!asn1_aint_get_uint64(&cbs, &val))

    return 0;

  *out_val = val;

  return 1;

}

int

ASN1_INTEGER_set_uint64(ASN1_INTEGER *aint, uint64_t val)

{

  asn1_aint_clear(aint);

  return asn1_aint_set_uint64(val, &aint->data, &aint->length);

}

int

ASN1_INTEGER_get_int64(int64_t *out_val, const ASN1_INTEGER *aint)

{

  CBS cbs;

  *out_val = 0;

  if (aint == NULL || aint->length < 0)

    return 0;

  if (aint->type != V_ASN1_INTEGER &&

      aint->type != V_ASN1_NEG_INTEGER) {

    ASN1error(ASN1_R_WRONG_INTEGER_TYPE);

    return 0;

  }

  CBS_init(&cbs, aint->data, aint->length);

  return asn1_aint_get_int64(&cbs, (aint->type == V_ASN1_NEG_INTEGER),

      out_val);

}

int

ASN1_INTEGER_set_int64(ASN1_INTEGER *aint, int64_t val)

{

  uint64_t uval;

  asn1_aint_clear(aint);

  uval = (uint64_t)val;

  if (val < 0) {

    aint->type = V_ASN1_NEG_INTEGER;

    uval = -uval;

  }

  return asn1_aint_set_uint64(uval, &aint->data, &aint->length);

}

long

ASN1_INTEGER_get(const ASN1_INTEGER *aint)

{

  int64_t val;

  if (aint == NULL)

    return 0;

  if (!ASN1_INTEGER_get_int64(&val, aint))

    return -1;

  if (val < LONG_MIN || val > LONG_MAX) {

    /* hmm... a bit ugly, return all ones */

    return -1;

  }

  return (long)val;

}

int

ASN1_INTEGER_set(ASN1_INTEGER *aint, long val)

{

  return ASN1_INTEGER_set_int64(aint, val);

}

ASN1_INTEGER *

BN_to_ASN1_INTEGER(const BIGNUM *bn, ASN1_INTEGER *ai)

{

  ASN1_INTEGER *ret;

  int len, j;

  if (ai == NULL)

    ret = ASN1_INTEGER_new();

  else

    ret = ai;

  if (ret == NULL) {

    ASN1error(ERR_R_NESTED_ASN1_ERROR);

    goto err;

  }

  if (!ASN1_INTEGER_valid(ret))

    goto err;

  if (BN_is_negative(bn))

    ret->type = V_ASN1_NEG_INTEGER;

  else

    ret->type = V_ASN1_INTEGER;

  j = BN_num_bits(bn);

  len = ((j == 0) ? 0 : ((j / 8) + 1));

  if (ret->length < len + 4) {

    unsigned char *new_data = realloc(ret->data, len + 4);

    if (!new_data) {

      ASN1error(ERR_R_MALLOC_FAILURE);

      goto err;

    }

    ret->data = new_data;

  }

  ret->length = BN_bn2bin(bn, ret->data);

  /* Correct zero case */

  if (!ret->length) {

    ret->data[0] = 0;

    ret->length = 1;

  }

  return (ret);

 err:

  if (ret != ai)

    ASN1_INTEGER_free(ret);

  return (NULL);

}

BIGNUM *

ASN1_INTEGER_to_BN(const ASN1_INTEGER *ai, BIGNUM *bn)

{

  BIGNUM *ret;

  if (!ASN1_INTEGER_valid(ai))

    return (NULL);

  if ((ret = BN_bin2bn(ai->data, ai->length, bn)) == NULL)

    ASN1error(ASN1_R_BN_LIB);

  else if (ai->type == V_ASN1_NEG_INTEGER)

    BN_set_negative(ret, 1);

  return (ret);

}

int

i2a_ASN1_INTEGER(BIO *bp, const ASN1_INTEGER *a)

{

  int i, n = 0;

  static const char h[] = "0123456789ABCDEF";

  char buf[2];

  if (a == NULL)

    return (0);

  if (a->type & V_ASN1_NEG) {

    if (BIO_write(bp, "-", 1) != 1)

      goto err;

    n = 1;

  }

  if (a->length == 0) {

    if (BIO_write(bp, "00", 2) != 2)

      goto err;

    n += 2;

  } else {

    for (i = 0; i < a->length; i++) {

      if ((i != 0) && (i % 35 == 0)) {

        if (BIO_write(bp, "\\\n", 2) != 2)

          goto err;

        n += 2;

      }

      buf[0] = h[((unsigned char)a->data[i] >> 4) & 0x0f];

      buf[1] = h[((unsigned char)a->data[i]) & 0x0f];

      if (BIO_write(bp, buf, 2) != 2)

        goto err;

      n += 2;

    }

  }

  return (n);

 err:

  return (-1);

}

int

a2i_ASN1_INTEGER(BIO *bp, ASN1_INTEGER *bs, char *buf, int size)

{

  int ret = 0;

  int i, j,k, m,n, again, bufsize;

  unsigned char *s = NULL, *sp;

  unsigned char *bufp;

  int num = 0, slen = 0, first = 1;

  bs->type = V_ASN1_INTEGER;

  bufsize = BIO_gets(bp, buf, size);

  for (;;) {

    if (bufsize < 1)

      goto err_sl;

    i = bufsize;

    if (buf[i - 1] == '\n')

      buf[--i] = '\0';

    if (i == 0)

      goto err_sl;

    if (buf[i - 1] == '\r')

      buf[--i] = '\0';

    if (i == 0)

      goto err_sl;

    if (buf[i - 1] == '\\') {

      i--;

      again = 1;

    } else

      again = 0;

    buf[i] = '\0';

    if (i < 2)

      goto err_sl;

    bufp = (unsigned char *)buf;

    if (first) {

      first = 0;

      if ((bufp[0] == '0') && (buf[1] == '0')) {

        bufp += 2;

        i -= 2;

      }

    }

    k = 0;

    if (i % 2 != 0) {

      ASN1error(ASN1_R_ODD_NUMBER_OF_CHARS);

      goto err;

    }

    i /= 2;

    if (num + i > slen) {

      if ((sp = recallocarray(s, slen, num + i, 1)) == NULL) {

        ASN1error(ERR_R_MALLOC_FAILURE);

        goto err;

      }

      s = sp;

      slen = num + i;

    }

    for (j = 0; j < i; j++, k += 2) {

      for (n = 0; n < 2; n++) {

        m = bufp[k + n];

        if ((m >= '0') && (m <= '9'))

          m -= '0';

        else if ((m >= 'a') && (m <= 'f'))

          m = m - 'a' + 10;

        else if ((m >= 'A') && (m <= 'F'))

          m = m - 'A' + 10;

        else {

          ASN1error(ASN1_R_NON_HEX_CHARACTERS);

          goto err;

        }

        s[num + j] <<= 4;

        s[num + j] |= m;

      }

    }

    num += i;

    if (again)

      bufsize = BIO_gets(bp, buf, size);

    else

      break;

  }

  bs->length = num;

  bs->data = s;

  return (1);

 err_sl:

  ASN1error(ASN1_R_SHORT_LINE);

 err:

  free(s);

  return (ret);

}

/*

 * This converts an ASN1 INTEGER into its content encoding.

 * The internal representation is an ASN1_STRING whose data is a big endian

 * representation of the value, ignoring the sign. The sign is determined by

 * the type: V_ASN1_INTEGER for positive and V_ASN1_NEG_INTEGER for negative.

 *

 * Positive integers are no problem: they are almost the same as the DER

 * encoding, except if the first byte is >= 0x80 we need to add a zero pad.

 *

 * Negative integers are a bit trickier...

 * The DER representation of negative integers is in 2s complement form.

 * The internal form is converted by complementing each octet and finally

 * adding one to the result. This can be done less messily with a little trick.

 * If the internal form has trailing zeroes then they will become FF by the

 * complement and 0 by the add one (due to carry) so just copy as many trailing

 * zeros to the destination as there are in the source. The carry will add one

 * to the last none zero octet: so complement this octet and add one and finally

 * complement any left over until you get to the start of the string.

 *

 * Padding is a little trickier too. If the first bytes is > 0x80 then we pad

 * with 0xff. However if the first byte is 0x80 and one of the following bytes

 * is non-zero we pad with 0xff. The reason for this distinction is that 0x80

 * followed by optional zeros isn't padded.

 */

int

i2c_ASN1_INTEGER(ASN1_INTEGER *a, unsigned char **pp)

{

  int pad = 0, ret, i, neg;

  unsigned char *p, *n, pb = 0;

  if (!ASN1_INTEGER_valid(a))

    return 0;

  neg = a->type & V_ASN1_NEG;

  if (a->length == 0)

    ret = 1;

  else {

    ret = a->length;

    i = a->data[0];

    if (!neg && (i > 127)) {

      pad = 1;

      pb = 0;

    } else if (neg) {

      if (i > 128) {

        pad = 1;

        pb = 0xFF;

      } else if (i == 128) {

        /*

         * Special case: if any other bytes non zero we pad:

         * otherwise we don't.

         */

        for (i = 1; i < a->length; i++) if (a->data[i]) {

          pad = 1;

          pb = 0xFF;

          break;

        }

      }

    }

    ret += pad;

  }

  if (pp == NULL)

    return (ret);

  p= *pp;

  if (pad)

    *(p++) = pb;

  if (a->length == 0)

    *(p++) = 0;

  else if (!neg)

    memcpy(p, a->data, a->length);

  else {

    /* Begin at the end of the encoding */

    n = a->data + a->length - 1;

    p += a->length - 1;

    i = a->length;

    /* Copy zeros to destination as long as source is zero */

    while (!*n) {

      *(p--) = 0;

      n--;

      i--;

    }

    /* Complement and increment next octet */

    *(p--) = ((*(n--)) ^ 0xff) + 1;

    i--;

    /* Complement any octets left */

    for (; i > 0; i--)

      *(p--) = *(n--) ^ 0xff;

  }

  *pp += ret;

  return (ret);

}

static void

asn1_aint_twos_complement(uint8_t *data, size_t data_len)

{

  uint8_t carry = 1;

  ssize_t i;

  for (i = data_len - 1; i >= 0; i--) {

    data[i] = (data[i] ^ 0xff) + carry;

    if (data[i] != 0)

      carry = 0;

  }

}

static int

asn1_aint_keep_twos_padding(const uint8_t *data, size_t data_len)

{

  size_t i;

  /*

   * If a two's complement value has a padding byte (0xff) and the rest

   * of the value is all zeros, the padding byte cannot be removed as when

   * converted from two's complement this becomes 0x01 (in the place of

   * the padding byte) followed by the same number of zero bytes.

   */

  if (data_len <= 1 || data[0] != 0xff)

    return 0;

  for (i = 1; i < data_len; i++) {

    if (data[i] != 0)

      return 0;

  }

  return 1;

}

int

c2i_ASN1_INTEGER_cbs(ASN1_INTEGER **out_aint, CBS *cbs)

{

  ASN1_INTEGER *aint = NULL;

  uint8_t *data = NULL;

  size_t data_len = 0;

  uint8_t padding, val;

  uint8_t negative = 0;

  int ret = 0;

  if (out_aint == NULL)

    goto err;

  if (*out_aint != NULL) {

    ASN1_INTEGER_free(*out_aint);

    *out_aint = NULL;

  }

  if (CBS_len(cbs) == 0) {

    /* XXX INVALID ENCODING? */

    ASN1error(ERR_R_ASN1_LENGTH_MISMATCH);

    goto err;

  }

  if (!CBS_peek_u8(cbs, &val))

    goto err;

  /* Top most bit indicates sign, padding is all zeros or all ones. */

  negative = (val >> 7);

  padding = ~(negative - 1) & 0xff;

  /*

   * Ensure that the first 9 bits are not all zero or all one, as per

   * X.690 section 8.3.2. Remove the padding octet if possible.

   */

  if (CBS_len(cbs) > 1 && val == padding) {

    if (!asn1_aint_keep_twos_padding(CBS_data(cbs), CBS_len(cbs))) {

      if (!CBS_get_u8(cbs, &padding))

        goto err;

      if (!CBS_peek_u8(cbs, &val))

        goto err;

      if ((val >> 7) == (padding >> 7)) {

        /* XXX INVALID ENCODING? */

        ASN1error(ERR_R_ASN1_LENGTH_MISMATCH);

        goto err;

      }

    }

  }

  if (!CBS_stow(cbs, &data, &data_len))

    goto err;

  if (data_len > INT_MAX)

    goto err;

  if ((aint = ASN1_INTEGER_new()) == NULL)

    goto err;

  /*

   * Negative integers are handled as a separate type - convert from

   * two's complement for internal representation.

   */

  if (negative) {

    aint->type = V_ASN1_NEG_INTEGER;

    asn1_aint_twos_complement(data, data_len);

  }

  aint->data = data;

  aint->length = (int)data_len;

  data = NULL;

  *out_aint = aint;

  aint = NULL;

  ret = 1;

 err:

  ASN1_INTEGER_free(aint);

  freezero(data, data_len);

  return ret;

}

ASN1_INTEGER *

c2i_ASN1_INTEGER(ASN1_INTEGER **out_aint, const unsigned char **pp, long len)

{

  ASN1_INTEGER *aint = NULL;

  CBS content;

  if (out_aint != NULL) {

    ASN1_INTEGER_free(*out_aint);

    *out_aint = NULL;

  }

  if (len < 0) {

    ASN1error(ASN1_R_LENGTH_ERROR);

    return NULL;

  }

  CBS_init(&content, *pp, len);

  if (!c2i_ASN1_INTEGER_cbs(&aint, &content))

    return NULL;

  *pp = CBS_data(&content);

  if (out_aint != NULL)

    *out_aint = aint;

  return aint;

}

int

i2d_ASN1_INTEGER(ASN1_INTEGER *a, unsigned char **out)

{

  return ASN1_item_i2d((ASN1_VALUE *)a, out, &ASN1_INTEGER_it);

}

ASN1_INTEGER *

d2i_ASN1_INTEGER(ASN1_INTEGER **a, const unsigned char **in, long len)

{

  return (ASN1_INTEGER *)ASN1_item_d2i((ASN1_VALUE **)a, in, len,

      &ASN1_INTEGER_it);

}

/* This is a version of d2i_ASN1_INTEGER that ignores the sign bit of

 * ASN1 integers: some broken software can encode a positive INTEGER

 * with its MSB set as negative (it doesn't add a padding zero).

 */

ASN1_INTEGER *

d2i_ASN1_UINTEGER(ASN1_INTEGER **a, const unsigned char **pp, long length)

{

  ASN1_INTEGER *ret = NULL;

  const unsigned char *p;

  unsigned char *s;

  long len;

  int inf, tag, xclass;

  int i;

  if ((a == NULL) || ((*a) == NULL)) {

    if ((ret = ASN1_INTEGER_new()) == NULL)

      return (NULL);

  } else

    ret = (*a);

  if (!ASN1_INTEGER_valid(ret)) {

    i = ERR_R_ASN1_LENGTH_MISMATCH;

    goto err;

  }

  p = *pp;

  inf = ASN1_get_object(&p, &len, &tag, &xclass, length);

  if (inf & 0x80) {

    i = ASN1_R_BAD_OBJECT_HEADER;

    goto err;

  }

  if (tag != V_ASN1_INTEGER) {

    i = ASN1_R_EXPECTING_AN_INTEGER;

    goto err;

  }

  /* We must malloc stuff, even for 0 bytes otherwise it

   * signifies a missing NULL parameter. */

  if (len < 0 || len > INT_MAX) {

    i = ERR_R_ASN1_LENGTH_MISMATCH;

    goto err;

  }

  s = malloc(len + 1);

  if (s == NULL) {

    i = ERR_R_MALLOC_FAILURE;

    goto err;

  }

  ret->type = V_ASN1_INTEGER;

  if (len) {

    if ((*p == 0) && (len != 1)) {

      p++;

      len--;

    }

    memcpy(s, p, len);

    p += len;

  }

  free(ret->data);

  ret->data = s;

  ret->length = (int)len;

  if (a != NULL)

    (*a) = ret;

  *pp = p;

  return (ret);

 err:

  ASN1error(i);

  if (a == NULL || *a != ret)

    ASN1_INTEGER_free(ret);

  return (NULL);

}