/*
 * 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 <http://www.gnu.org/licenses/>
 *
 */

/* This file contains the functions needed for RSA/DSA public key
 * encryption and signatures. 
 */

#include <gnutls_int.h>
#include <gnutls_mpi.h>
#include <gnutls_pk.h>
#include <gnutls_errors.h>
#include <gnutls_datum.h>
#include <gnutls_global.h>
#include <gnutls_num.h>
#include "debug.h"
#include <x509/x509_int.h>
#include <x509/common.h>
#include <random.h>

/* encodes the Dss-Sig-Value structure
 */
int
_gnutls_encode_ber_rs_raw(gnutls_datum_t * sig_value,
			  const gnutls_datum_t * r,
			  const gnutls_datum_t * s)
{
	ASN1_TYPE sig;
	int result;

	if ((result =
	     asn1_create_element(_gnutls_get_gnutls_asn(),
				 "GNUTLS.DSASignatureValue",
				 &sig)) != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(result);
	}

	result = asn1_write_value(sig, "r", r->data, r->size);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		asn1_delete_structure(&sig);
		return _gnutls_asn2err(result);
	}

	result = asn1_write_value(sig, "s", s->data, s->size);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		asn1_delete_structure(&sig);
		return _gnutls_asn2err(result);
	}

	result = _gnutls_x509_der_encode(sig, "", sig_value, 0);
	asn1_delete_structure(&sig);

	if (result < 0)
		return gnutls_assert_val(result);

	return 0;
}

int
_gnutls_encode_ber_rs(gnutls_datum_t * sig_value, bigint_t r, bigint_t s)
{
	ASN1_TYPE sig;
	int result;

	if ((result =
	     asn1_create_element(_gnutls_get_gnutls_asn(),
				 "GNUTLS.DSASignatureValue",
				 &sig)) != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(result);
	}

	result = _gnutls_x509_write_int(sig, "r", r, 1);
	if (result < 0) {
		gnutls_assert();
		asn1_delete_structure(&sig);
		return result;
	}

	result = _gnutls_x509_write_int(sig, "s", s, 1);
	if (result < 0) {
		gnutls_assert();
		asn1_delete_structure(&sig);
		return result;
	}

	result = _gnutls_x509_der_encode(sig, "", sig_value, 0);
	asn1_delete_structure(&sig);

	if (result < 0)
		return gnutls_assert_val(result);

	return 0;
}


/* decodes the Dss-Sig-Value structure
 */
int
_gnutls_decode_ber_rs(const gnutls_datum_t * sig_value, bigint_t * r,
		      bigint_t * s)
{
	ASN1_TYPE sig;
	int result;

	if ((result =
	     asn1_create_element(_gnutls_get_gnutls_asn(),
				 "GNUTLS.DSASignatureValue",
				 &sig)) != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(result);
	}

	result =
	    asn1_der_decoding(&sig, sig_value->data, sig_value->size,
			      NULL);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		asn1_delete_structure(&sig);
		return _gnutls_asn2err(result);
	}

	result = _gnutls_x509_read_int(sig, "r", r);
	if (result < 0) {
		gnutls_assert();
		asn1_delete_structure(&sig);
		return result;
	}

	result = _gnutls_x509_read_int(sig, "s", s);
	if (result < 0) {
		gnutls_assert();
		_gnutls_mpi_release(s);
		asn1_delete_structure(&sig);
		return result;
	}

	asn1_delete_structure(&sig);

	return 0;
}

/* some generic pk functions */

int _gnutls_pk_params_copy(gnutls_pk_params_st * dst,
			   const gnutls_pk_params_st * src)
{
	unsigned int i, j;
	dst->params_nr = 0;

	if (src == NULL || src->params_nr == 0) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	for (i = 0; i < src->params_nr; i++) {
		dst->params[i] = _gnutls_mpi_set(NULL, src->params[i]);
		if (dst->params[i] == NULL) {
			for (j = 0; j < i; j++)
				_gnutls_mpi_release(&dst->params[j]);
			return GNUTLS_E_MEMORY_ERROR;
		}
		dst->params_nr++;
	}

	return 0;
}

void gnutls_pk_params_init(gnutls_pk_params_st * p)
{
	memset(p, 0, sizeof(gnutls_pk_params_st));
}

void gnutls_pk_params_release(gnutls_pk_params_st * p)
{
	unsigned int i;
	for (i = 0; i < p->params_nr; i++) {
		_gnutls_mpi_release(&p->params[i]);
	}
	p->params_nr = 0;
}

void gnutls_pk_params_clear(gnutls_pk_params_st * p)
{
	unsigned int i;
	for (i = 0; i < p->params_nr; i++) {
		if (p->params[i] != NULL)
			_gnutls_mpi_clear(p->params[i]);
	}
}

int
_gnutls_pk_get_hash_algorithm(gnutls_pk_algorithm_t pk,
			      gnutls_pk_params_st * params,
			      gnutls_digest_algorithm_t * dig,
			      unsigned int *mand)
{
	if (mand) {
		if (pk == GNUTLS_PK_DSA)
			*mand = 1;
		else
			*mand = 0;
	}

	return _gnutls_x509_verify_algorithm(dig, NULL, pk, params);

}

/* Writes the digest information and the digest in a DER encoded
 * structure. The digest info is allocated and stored into the info structure.
 */
int
encode_ber_digest_info(const mac_entry_st * e,
		       const gnutls_datum_t * digest,
		       gnutls_datum_t * output)
{
	ASN1_TYPE dinfo = ASN1_TYPE_EMPTY;
	int result;
	const char *algo;
	uint8_t *tmp_output;
	int tmp_output_size;

	algo = _gnutls_x509_mac_to_oid(e);
	if (algo == NULL) {
		gnutls_assert();
		_gnutls_debug_log("Hash algorithm: %d has no OID\n",
				  e->id);
		return GNUTLS_E_UNKNOWN_PK_ALGORITHM;
	}

	if ((result = asn1_create_element(_gnutls_get_gnutls_asn(),
					  "GNUTLS.DigestInfo",
					  &dinfo)) != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(result);
	}

	result =
	    asn1_write_value(dinfo, "digestAlgorithm.algorithm", algo, 1);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		asn1_delete_structure(&dinfo);
		return _gnutls_asn2err(result);
	}

	/* Write an ASN.1 NULL in the parameters field.  This matches RFC
	   3279 and RFC 4055, although is arguable incorrect from a historic
	   perspective (see those documents for more information).
	   Regardless of what is correct, this appears to be what most
	   implementations do.  */
	result = asn1_write_value(dinfo, "digestAlgorithm.parameters",
				  ASN1_NULL, ASN1_NULL_SIZE);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		asn1_delete_structure(&dinfo);
		return _gnutls_asn2err(result);
	}

	result =
	    asn1_write_value(dinfo, "digest", digest->data, digest->size);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		asn1_delete_structure(&dinfo);
		return _gnutls_asn2err(result);
	}

	tmp_output_size = 0;
	result = asn1_der_coding(dinfo, "", NULL, &tmp_output_size, NULL);
	if (result != ASN1_MEM_ERROR) {
		gnutls_assert();
		asn1_delete_structure(&dinfo);
		return _gnutls_asn2err(result);
	}

	tmp_output = gnutls_malloc(tmp_output_size);
	if (tmp_output == NULL) {
		gnutls_assert();
		asn1_delete_structure(&dinfo);
		return GNUTLS_E_MEMORY_ERROR;
	}

	result =
	    asn1_der_coding(dinfo, "", tmp_output, &tmp_output_size, NULL);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		asn1_delete_structure(&dinfo);
		return _gnutls_asn2err(result);
	}

	asn1_delete_structure(&dinfo);

	output->size = tmp_output_size;
	output->data = tmp_output;

	return 0;
}

/* Reads the digest information.
 * we use DER here, although we should use BER. It works fine
 * anyway.
 */
int
decode_ber_digest_info(const gnutls_datum_t * info,
		       gnutls_digest_algorithm_t * hash,
		       uint8_t * digest, unsigned int *digest_size)
{
	ASN1_TYPE dinfo = ASN1_TYPE_EMPTY;
	int result;
	char str[1024];
	int len;

	if ((result = asn1_create_element(_gnutls_get_gnutls_asn(),
					  "GNUTLS.DigestInfo",
					  &dinfo)) != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(result);
	}

	result = asn1_der_decoding(&dinfo, info->data, info->size, NULL);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		asn1_delete_structure(&dinfo);
		return _gnutls_asn2err(result);
	}

	len = sizeof(str) - 1;
	result =
	    asn1_read_value(dinfo, "digestAlgorithm.algorithm", str, &len);
	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		asn1_delete_structure(&dinfo);
		return _gnutls_asn2err(result);
	}

	*hash = _gnutls_x509_oid_to_digest(str);

	if (*hash == GNUTLS_DIG_UNKNOWN) {

		_gnutls_debug_log("verify.c: HASH OID: %s\n", str);

		gnutls_assert();
		asn1_delete_structure(&dinfo);
		return GNUTLS_E_UNKNOWN_ALGORITHM;
	}

	len = sizeof(str) - 1;
	result =
	    asn1_read_value(dinfo, "digestAlgorithm.parameters", str,
			    &len);
	/* To avoid permitting garbage in the parameters field, either the
	   parameters field is not present, or it contains 0x05 0x00. */
	if (!(result == ASN1_ELEMENT_NOT_FOUND ||
	      (result == ASN1_SUCCESS && len == ASN1_NULL_SIZE &&
	       memcmp(str, ASN1_NULL, ASN1_NULL_SIZE) == 0))) {
		gnutls_assert();
		asn1_delete_structure(&dinfo);
		return GNUTLS_E_ASN1_GENERIC_ERROR;
	}

	len = *digest_size;
	result = asn1_read_value(dinfo, "digest", digest, &len);

	if (result != ASN1_SUCCESS) {
		gnutls_assert();
		*digest_size = len;
		asn1_delete_structure(&dinfo);
		return _gnutls_asn2err(result);
	}

	*digest_size = len;
	asn1_delete_structure(&dinfo);

	return 0;
}
