/*
 * Copyright (C) 2001,2002,2003 Nikos Mavroyanopoulos
 * Copyright (C) 2004 Free Software Foundation
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307  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;

    /* 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;
}


/* 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;
}