/*

 * Copyright (C) 2001-2012 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 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/>

 *

 */

/* Here lie everything that has to do with large numbers, libgcrypt and

 * other stuff that didn't fit anywhere else.

 */

#include "gnutls_int.h"

#include <libtasn1.h>

#include "errors.h"

#include <num.h>

#include <mpi.h>

#include <random.h>

#include <x509/x509_int.h>

/* Functions that refer to the mpi library.

 */

/* Returns a random number r, 0 < r < p */

bigint_t

_gnutls_mpi_random_modp(bigint_t r, bigint_t p, gnutls_rnd_level_t level)

{

  size_t size;

  int ret;

  bigint_t tmp;

  uint8_t tmpbuf[512];

  uint8_t *buf;

  int buf_release = 0;

  size = ((_gnutls_mpi_get_nbits(p) + 64) / 8) + 1;

  if (size < sizeof(tmpbuf)) {

    buf = tmpbuf;

  } else {

    buf = gnutls_malloc(size);

    if (buf == NULL) {

      gnutls_assert();

      goto cleanup;

    }

    buf_release = 1;

  }

  ret = gnutls_rnd(level, buf, size);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  ret = _gnutls_mpi_init_scan(&tmp, buf, size);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  ret = _gnutls_mpi_modm(tmp, tmp, p);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  if (_gnutls_mpi_cmp_ui(tmp, 0) == 0) {

    ret = _gnutls_mpi_add_ui(tmp, tmp, 1);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

  }

  if (buf_release != 0) {

    gnutls_free(buf);

  }

  if (r != NULL) {

    ret = _gnutls_mpi_set(r, tmp);

    if (ret < 0)

      goto cleanup;

    _gnutls_mpi_release(&tmp);

    return r;

  }

  return tmp;

 cleanup:

  if (buf_release != 0)

    gnutls_free(buf);

  return NULL;

}

/* returns %GNUTLS_E_SUCCESS (0) on success

 */

int _gnutls_mpi_init_scan(bigint_t * ret_mpi, const void *buffer, size_t nbytes)

{

  bigint_t r;

  int ret;

  ret = _gnutls_mpi_init(&r);

  if (ret < 0)

    return gnutls_assert_val(ret);

  ret = _gnutls_mpi_scan(r, buffer, nbytes);

  if (ret < 0) {

    gnutls_assert();

    _gnutls_mpi_release(&r);

    return ret;

  }

  *ret_mpi = r;

  return 0;

}

/* returns %GNUTLS_E_SUCCESS (0) on success. Fails if the number is zero.

 */

int

_gnutls_mpi_init_scan_nz(bigint_t * ret_mpi, const void *buffer, size_t nbytes)

{

  int ret;

  ret = _gnutls_mpi_init_scan(ret_mpi, buffer, nbytes);

  if (ret < 0)

    return ret;

  /* MPIs with 0 bits are illegal

   */

  if (_gnutls_mpi_cmp_ui(*ret_mpi, 0) == 0) {

    _gnutls_mpi_release(ret_mpi);

    return GNUTLS_E_MPI_SCAN_FAILED;

  }

  return 0;

}

int

_gnutls_mpi_init_scan_le(bigint_t * ret_mpi, const void *buffer, size_t nbytes)

{

  bigint_t r;

  int ret;

  ret = _gnutls_mpi_init(&r);

  if (ret < 0)

    return gnutls_assert_val(ret);

  ret = _gnutls_mpi_scan_le(r, buffer, nbytes);

  if (ret < 0) {

    gnutls_assert();

    _gnutls_mpi_release(&r);

    return ret;

  }

  *ret_mpi = r;

  return 0;

}

int _gnutls_mpi_dprint_le(const bigint_t a, gnutls_datum_t * dest)

{

  int ret;

  uint8_t *buf = NULL;

  size_t bytes = 0;

  if (dest == NULL || a == NULL)

    return GNUTLS_E_INVALID_REQUEST;

  _gnutls_mpi_print_le(a, NULL, &bytes);

  if (bytes != 0)

    buf = gnutls_malloc(bytes);

  if (buf == NULL)

    return GNUTLS_E_MEMORY_ERROR;

  ret = _gnutls_mpi_print_le(a, buf, &bytes);

  if (ret < 0) {

    gnutls_free(buf);

    return ret;

  }

  dest->data = buf;

  dest->size = bytes;

  return 0;

}

/* Always has the first bit zero */

int _gnutls_mpi_dprint_lz(const bigint_t a, gnutls_datum_t * dest)

{

  int ret;

  uint8_t *buf = NULL;

  size_t bytes = 0;

  if (dest == NULL || a == NULL)

    return GNUTLS_E_INVALID_REQUEST;

  _gnutls_mpi_print_lz(a, NULL, &bytes);

  if (bytes != 0)

    buf = gnutls_malloc(bytes);

  if (buf == NULL)

    return GNUTLS_E_MEMORY_ERROR;

  ret = _gnutls_mpi_print_lz(a, buf, &bytes);

  if (ret < 0) {

    gnutls_free(buf);

    return ret;

  }

  dest->data = buf;

  dest->size = bytes;

  return 0;

}

int _gnutls_mpi_dprint(const bigint_t a, gnutls_datum_t * dest)

{

  int ret;

  uint8_t *buf = NULL;

  size_t bytes = 0;

  if (dest == NULL || a == NULL)

    return GNUTLS_E_INVALID_REQUEST;

  _gnutls_mpi_print(a, NULL, &bytes);

  if (bytes != 0)

    buf = gnutls_malloc(bytes);

  if (buf == NULL)

    return GNUTLS_E_MEMORY_ERROR;

  ret = _gnutls_mpi_print(a, buf, &bytes);

  if (ret < 0) {

    gnutls_free(buf);

    return ret;

  }

  dest->data = buf;

  dest->size = bytes;

  return 0;

}

/* This function will copy the mpi data into a datum,

 * but will set minimum size to 'size'. That means that

 * the output value is left padded with zeros.

 */

int

_gnutls_mpi_dprint_size(const bigint_t a, gnutls_datum_t * dest, size_t size)

{

  int ret;

  uint8_t *buf = NULL;

  size_t bytes = 0;

  unsigned int i;

  if (dest == NULL || a == NULL)

    return GNUTLS_E_INVALID_REQUEST;

  _gnutls_mpi_print(a, NULL, &bytes);

  if (bytes != 0)

    buf = gnutls_malloc(MAX(size, bytes));

  if (buf == NULL)

    return GNUTLS_E_MEMORY_ERROR;

  if (bytes <= size) {

    size_t diff = size - bytes;

    for (i = 0; i < diff; i++)

      buf[i] = 0;

    ret = _gnutls_mpi_print(a, &buf[diff], &bytes);

  } else {

    ret = _gnutls_mpi_print(a, buf, &bytes);

  }

  if (ret < 0) {

    gnutls_free(buf);

    return ret;

  }

  dest->data = buf;

  dest->size = MAX(size, bytes);

  return 0;

}

/* like _gnutls_mpi_dprint_size, but prints into preallocated byte buffer */

int _gnutls_mpi_bprint_size(const bigint_t a, uint8_t * buf, size_t size)

{

  int result;

  size_t bytes = 0;

  result = _gnutls_mpi_print(a, NULL, &bytes);

  if (result != GNUTLS_E_SHORT_MEMORY_BUFFER)

    return gnutls_assert_val(result);

  if (bytes <= size) {

    unsigned i;

    size_t diff = size - bytes;

    for (i = 0; i < diff; i++)

      buf[i] = 0;

    result = _gnutls_mpi_print(a, &buf[diff], &bytes);

  } else {

    result = _gnutls_mpi_print(a, buf, &bytes);

  }

  return result;

}

/* Flags for __gnutls_x509_read_int() and __gnutls_x509_write_int */

#define GNUTLS_X509_INT_OVERWRITE (1 << 0)

#define GNUTLS_X509_INT_LE    (1 << 1)

#define GNUTLS_X509_INT_LZ    (1 << 2)  /* write only */

/* this function reads an integer

 * from asn1 structs. Combines the read and mpi_scan

 * steps.

 */

static int

__gnutls_x509_read_int(asn1_node node, const char *value,

           bigint_t * ret_mpi, unsigned int flags)

{

  int result;

  uint8_t *tmpstr = NULL;

  int tmpstr_size;

  tmpstr_size = 0;

  result = asn1_read_value(node, value, NULL, &tmpstr_size);

  if (result != ASN1_MEM_ERROR) {

    gnutls_assert();

    return _gnutls_asn2err(result);

  }

  tmpstr = gnutls_malloc(tmpstr_size);

  if (tmpstr == NULL) {

    gnutls_assert();

    return GNUTLS_E_MEMORY_ERROR;

  }

  result = asn1_read_value(node, value, tmpstr, &tmpstr_size);

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    gnutls_free(tmpstr);

    return _gnutls_asn2err(result);

  }

  if (flags & GNUTLS_X509_INT_LE)

    result = _gnutls_mpi_init_scan_le(ret_mpi, tmpstr, tmpstr_size);

  else

    result = _gnutls_mpi_init_scan(ret_mpi, tmpstr, tmpstr_size);

  if (flags & GNUTLS_X509_INT_OVERWRITE)

    zeroize_key(tmpstr, tmpstr_size);

  gnutls_free(tmpstr);

  if (result < 0) {

    gnutls_assert();

    return result;

  }

  return 0;

}

int _gnutls_x509_read_int(asn1_node node, const char *value, bigint_t * ret_mpi)

{

  return __gnutls_x509_read_int(node, value, ret_mpi, 0);

}

int

_gnutls_x509_read_key_int(asn1_node node, const char *value, bigint_t * ret_mpi)

{

  return __gnutls_x509_read_int(node, value, ret_mpi,

              GNUTLS_X509_INT_OVERWRITE);

}

int

_gnutls_x509_read_key_int_le(asn1_node node, const char *value,

           bigint_t * ret_mpi)

{

  return __gnutls_x509_read_int(node, value, ret_mpi,

              GNUTLS_X509_INT_OVERWRITE |

              GNUTLS_X509_INT_LE);

}

/* Writes the specified integer into the specified node.

 */

static int

__gnutls_x509_write_int(asn1_node node, const char *value, bigint_t mpi,

      unsigned int flags)

{

  uint8_t *tmpstr;

  size_t s_len;

  int result;

  s_len = 0;

  if (flags & GNUTLS_X509_INT_LZ)

    result = _gnutls_mpi_print_lz(mpi, NULL, &s_len);

  else if (GNUTLS_X509_INT_LE)

    result = _gnutls_mpi_print_le(mpi, NULL, &s_len);

  else

    result = _gnutls_mpi_print(mpi, NULL, &s_len);

  if (result != GNUTLS_E_SHORT_MEMORY_BUFFER) {

    gnutls_assert();

    return result;

  }

  tmpstr = gnutls_malloc(s_len);

  if (tmpstr == NULL) {

    gnutls_assert();

    return GNUTLS_E_MEMORY_ERROR;

  }

  if (flags & GNUTLS_X509_INT_LZ)

    result = _gnutls_mpi_print_lz(mpi, tmpstr, &s_len);

  else if (GNUTLS_X509_INT_LE)

    result = _gnutls_mpi_print_le(mpi, tmpstr, &s_len);

  else

    result = _gnutls_mpi_print(mpi, tmpstr, &s_len);

  if (result != 0) {

    gnutls_assert();

    gnutls_free(tmpstr);

    return GNUTLS_E_MPI_PRINT_FAILED;

  }

  result = asn1_write_value(node, value, tmpstr, s_len);

  if (flags & GNUTLS_X509_INT_OVERWRITE)

    zeroize_key(tmpstr, s_len);

  gnutls_free(tmpstr);

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    return _gnutls_asn2err(result);

  }

  return 0;

}

int

_gnutls_x509_write_int(asn1_node node, const char *value, bigint_t mpi, int lz)

{

  return __gnutls_x509_write_int(node, value, mpi,

               lz ? GNUTLS_X509_INT_LZ : 0);

}

int

_gnutls_x509_write_key_int(asn1_node node, const char *value, bigint_t mpi,

         int lz)

{

  return __gnutls_x509_write_int(node, value, mpi,

               (lz ? GNUTLS_X509_INT_LZ : 0) |

               GNUTLS_X509_INT_OVERWRITE);

}

int

_gnutls_x509_write_key_int_le(asn1_node node, const char *value, bigint_t mpi)

{

  return __gnutls_x509_write_int(node, value, mpi,

               GNUTLS_X509_INT_OVERWRITE |

               GNUTLS_X509_INT_LE);

}