path: root/lib/gnutls_mpi.c

/*
 * Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation
 *
 * Author: Nikos Mavroyanopoulos
 *
 * This file is part of GNUTLS.
 *
 * The GNUTLS library 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
 * USA
 *
 */

/* 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 <gnutls_errors.h>
#include <gnutls_num.h>

/* Functions that refer to the libgcrypt library.
 */

void
_gnutls_mpi_release (mpi_t * x)
{
  if (*x == NULL)
    return;
  gcry_mpi_release (*x);
  *x = NULL;
}

/* returns zero on success
 */
int
_gnutls_mpi_scan (mpi_t * ret_mpi, const opaque * buffer, size_t * nbytes)
{
  int ret;

  ret = gcry_mpi_scan (ret_mpi, GCRYMPI_FMT_USG, buffer, *nbytes, nbytes);
  if (ret)
    return GNUTLS_E_MPI_SCAN_FAILED;

  return 0;
}

/* returns zero on success. Fails if the number is zero.
 */
int
_gnutls_mpi_scan_nz (mpi_t * ret_mpi, const opaque * buffer, size_t * nbytes)
{
  int ret;

  ret = gcry_mpi_scan (ret_mpi, GCRYMPI_FMT_USG, buffer, *nbytes, nbytes);
  if (ret)
    return GNUTLS_E_MPI_SCAN_FAILED;

  /* MPIs with 0 bits are illegal
   */
  if (_gnutls_mpi_get_nbits (*ret_mpi) == 0)
    {
      _gnutls_mpi_release (ret_mpi);
      return GNUTLS_E_MPI_SCAN_FAILED;
    }

  return 0;
}

int
_gnutls_mpi_scan_pgp (mpi_t * ret_mpi, const opaque * buffer, size_t * nbytes)
{
  int ret;
  ret = gcry_mpi_scan (ret_mpi, GCRYMPI_FMT_PGP, buffer, *nbytes, nbytes);
  if (ret)
    return GNUTLS_E_MPI_SCAN_FAILED;

  /* MPIs with 0 bits are illegal
   */
  if (_gnutls_mpi_get_nbits (*ret_mpi) == 0)
    {
      _gnutls_mpi_release (ret_mpi);
      return GNUTLS_E_MPI_SCAN_FAILED;
    }

  return 0;
}

int
_gnutls_mpi_print (void *buffer, size_t * nbytes, const mpi_t a)
{
  int ret;

  if (nbytes == NULL || a == NULL)
    return GNUTLS_E_INVALID_REQUEST;

  ret = gcry_mpi_print (GCRYMPI_FMT_USG, buffer, *nbytes, nbytes, a);
  if (!ret)
    return 0;

  return GNUTLS_E_MPI_PRINT_FAILED;
}

/* Always has the first bit zero */
int
_gnutls_mpi_print_lz (void *buffer, size_t * nbytes, const mpi_t a)
{
  int ret;

  if (nbytes == NULL || a == NULL)
    return GNUTLS_E_INVALID_REQUEST;

  ret = gcry_mpi_print (GCRYMPI_FMT_STD, buffer, *nbytes, nbytes, a);
  if (!ret)
    return 0;

  return GNUTLS_E_MPI_PRINT_FAILED;
}

/* Always has the first bit zero */
int
_gnutls_mpi_dprint_lz (gnutls_datum_t * dest, const mpi_t a)
{
  int ret;
  opaque *buf = NULL;
  size_t bytes = 0;

  if (dest == NULL || a == NULL)
    return GNUTLS_E_INVALID_REQUEST;

  gcry_mpi_print (GCRYMPI_FMT_STD, NULL, 0, &bytes, a);

  if (bytes != 0)
    buf = gnutls_malloc (bytes);
  if (buf == NULL)
    return GNUTLS_E_MEMORY_ERROR;

  ret = gcry_mpi_print (GCRYMPI_FMT_STD, buf, bytes, &bytes, a);
  if (!ret)
    {
      dest->data = buf;
      dest->size = bytes;
      return 0;
    }

  gnutls_free (buf);
  return GNUTLS_E_MPI_PRINT_FAILED;
}

int
_gnutls_mpi_dprint (gnutls_datum_t * dest, const mpi_t a)
{
  int ret;
  opaque *buf = NULL;
  size_t bytes = 0;

  if (dest == NULL || a == NULL)
    return GNUTLS_E_INVALID_REQUEST;

  gcry_mpi_print (GCRYMPI_FMT_USG, NULL, 0, &bytes, a);

  if (bytes != 0)
    buf = gnutls_malloc (bytes);
  if (buf == NULL)
    return GNUTLS_E_MEMORY_ERROR;

  ret = gcry_mpi_print (GCRYMPI_FMT_USG, buf, bytes, &bytes, a);
  if (!ret)
    {
      dest->data = buf;
      dest->size = bytes;
      return 0;
    }

  gnutls_free (buf);
  return GNUTLS_E_MPI_PRINT_FAILED;
}


/* this function reads an integer
 * from asn1 structs. Combines the read and mpi_scan
 * steps.
 */
int
_gnutls_x509_read_int (ASN1_TYPE node, const char *value, mpi_t * ret_mpi)
{
  int result;
  size_t s_len;
  opaque *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_alloca (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_afree (tmpstr);
      return _gnutls_asn2err (result);
    }

  s_len = tmpstr_size;
  if (_gnutls_mpi_scan (ret_mpi, tmpstr, &s_len) != 0)
    {
      gnutls_assert ();
      gnutls_afree (tmpstr);
      return GNUTLS_E_MPI_SCAN_FAILED;
    }

  gnutls_afree (tmpstr);

  return 0;
}

/* Writes the specified integer into the specified node.
 */
int
_gnutls_x509_write_int (ASN1_TYPE node, const char *value, mpi_t mpi, int lz)
{
  opaque *tmpstr;
  size_t s_len;
  int result;

  s_len = 0;
  if (lz)
    result = _gnutls_mpi_print_lz (NULL, &s_len, mpi);
  else
    result = _gnutls_mpi_print (NULL, &s_len, mpi);

  tmpstr = gnutls_alloca (s_len);
  if (tmpstr == NULL)
    {
      gnutls_assert ();
      return GNUTLS_E_MEMORY_ERROR;
    }

  if (lz)
    result = _gnutls_mpi_print_lz (tmpstr, &s_len, mpi);
  else
    result = _gnutls_mpi_print (tmpstr, &s_len, mpi);

  if (result != 0)
    {
      gnutls_assert ();
      gnutls_afree (tmpstr);
      return GNUTLS_E_MPI_PRINT_FAILED;
    }

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

  gnutls_afree (tmpstr);

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

  return 0;
}