/*
 * Copyright(c) 2019 Free Software Foundation, Inc.
 *
 * This file is part of libtasn1.
 *
 * Libtasn1 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 3 of the License, or
 * (at your option) any later version.
 *
 * Libtasn1 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 libtasn1.  If not, see <https://www.gnu.org/licenses/>.
 *
 * This fuzzer is testing arbitrary DER input data with GnuTLS's ASN.1 definition (lib/gnutls.asn).
 * So, any issues found here likely have a real world impact on every software using libgnutls.
 */

#include <config.h>

#include <assert.h> // assert
#include <stdlib.h> // malloc, free
#include <string.h> // strcmp, memcpy

#include "libtasn1.h"
#include "fuzzer.h"

/*
 * This is a ASN.1 definition array used by GnuTLS.
 * It is created from lib/gnutls.asn over at the GnuTLS project.
 */
const asn1_static_node gnutls_asn1_tab[] = {
  { "GNUTLS", 536872976, NULL },
  { NULL, 1073741836, NULL },
  { "RSAPublicKey", 1610612741, NULL },
  { "modulus", 1073741827, NULL },
  { "publicExponent", 3, NULL },
  { "RSAPrivateKey", 1610612741, NULL },
  { "version", 1073741827, NULL },
  { "modulus", 1073741827, NULL },
  { "publicExponent", 1073741827, NULL },
  { "privateExponent", 1073741827, NULL },
  { "prime1", 1073741827, NULL },
  { "prime2", 1073741827, NULL },
  { "exponent1", 1073741827, NULL },
  { "exponent2", 1073741827, NULL },
  { "coefficient", 1073741827, NULL },
  { "otherPrimeInfos", 16386, "OtherPrimeInfos"},
  { "ProvableSeed", 1610612741, NULL },
  { "algorithm", 1073741836, NULL },
  { "seed", 7, NULL },
  { "OtherPrimeInfos", 1612709899, NULL },
  { "MAX", 1074266122, "1"},
  { NULL, 2, "OtherPrimeInfo"},
  { "OtherPrimeInfo", 1610612741, NULL },
  { "prime", 1073741827, NULL },
  { "exponent", 1073741827, NULL },
  { "coefficient", 3, NULL },
  { "AlgorithmIdentifier", 1610612741, NULL },
  { "algorithm", 1073741836, NULL },
  { "parameters", 541081613, NULL },
  { "algorithm", 1, NULL },
  { "DigestInfo", 1610612741, NULL },
  { "digestAlgorithm", 1073741826, "DigestAlgorithmIdentifier"},
  { "digest", 7, NULL },
  { "DigestAlgorithmIdentifier", 1073741826, "AlgorithmIdentifier"},
  { "DSAPublicKey", 1073741827, NULL },
  { "DSAParameters", 1610612741, NULL },
  { "p", 1073741827, NULL },
  { "q", 1073741827, NULL },
  { "g", 3, NULL },
  { "DSASignatureValue", 1610612741, NULL },
  { "r", 1073741827, NULL },
  { "s", 3, NULL },
  { "DSAPrivateKey", 1610612741, NULL },
  { "version", 1073741827, NULL },
  { "p", 1073741827, NULL },
  { "q", 1073741827, NULL },
  { "g", 1073741827, NULL },
  { "Y", 1073741827, NULL },
  { "priv", 3, NULL },
  { "DHParameter", 1610612741, NULL },
  { "prime", 1073741827, NULL },
  { "base", 1073741827, NULL },
  { "privateValueLength", 16387, NULL },
  { "ECParameters", 1610612754, NULL },
  { "namedCurve", 12, NULL },
  { "ECPrivateKey", 1610612741, NULL },
  { "Version", 1073741827, NULL },
  { "privateKey", 1073741831, NULL },
  { "parameters", 1610637314, "ECParameters"},
  { NULL, 2056, "0"},
  { "publicKey", 536895494, NULL },
  { NULL, 2056, "1"},
  { "PrincipalName", 1610612741, NULL },
  { "name-type", 1610620931, NULL },
  { NULL, 2056, "0"},
  { "name-string", 536879115, NULL },
  { NULL, 1073743880, "1"},
  { NULL, 27, NULL },
  { "KRB5PrincipalName", 1610612741, NULL },
  { "realm", 1610620955, NULL },
  { NULL, 2056, "0"},
  { "principalName", 536879106, "PrincipalName"},
  { NULL, 2056, "1"},
  { "RSAPSSParameters", 1610612741, NULL },
  { "hashAlgorithm", 1610637314, "AlgorithmIdentifier"},
  { NULL, 2056, "0"},
  { "maskGenAlgorithm", 1610637314, "AlgorithmIdentifier"},
  { NULL, 2056, "1"},
  { "saltLength", 1610653699, NULL },
  { NULL, 1073741833, "20"},
  { NULL, 2056, "2"},
  { "trailerField", 536911875, NULL },
  { NULL, 1073741833, "1"},
  { NULL, 2056, "3"},
  { "GOSTParameters", 1610612741, NULL },
  { "publicKeyParamSet", 1073741836, NULL },
  { "digestParamSet", 1073741836, NULL },
  { "encryptionParamSet", 16396, NULL },
  { "GOSTPrivateKey", 1073741831, NULL },
  { "GOSTPrivateKeyOld", 3, NULL },
  { NULL, 0, NULL }
};

int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
{
	static asn1_node _gnutls_gnutls_asn = NULL;
	static int first = 1;
	asn1_node dn;
	int res;

	if (size > 10000) // same as max_len = 10000 in .options file
		return 0;

	if (first) {
		first = 0;

		// from _gnutls_global_init()
		res = asn1_array2tree(gnutls_asn1_tab, &_gnutls_gnutls_asn, NULL);
		assert(res == ASN1_SUCCESS);
	}

	// from gnutls_dh_params_import_pkcs3()
	if ((res = asn1_create_element(_gnutls_gnutls_asn, "GNUTLS.DHParameter", &dn)) == ASN1_SUCCESS) {
		// from cert_get_issuer_dn()
		res = asn1_der_decoding(&dn, data, size, NULL);
		asn1_delete_structure(&dn);
	}

	// from _gnutls_x509_write_gost_params()
	if ((res = asn1_create_element(_gnutls_gnutls_asn, "GNUTLS.GOSTParameters", &dn)) == ASN1_SUCCESS) {
		if ((res = asn1_write_value(dn, "digestParamSet", "1.2.643.7.1.1.2.2", 1)) == ASN1_SUCCESS) {
			// from cert_get_issuer_dn()
			res = asn1_der_decoding(&dn, data, size, NULL);

			// from _gnutls_x509_der_encode()
			int dersize = 0;
			if ((res = asn1_der_coding(dn, "", NULL, &dersize, NULL)) == ASN1_MEM_ERROR) {
				void *der = malloc(dersize);
				assert(der);
				res = asn1_der_coding(dn, "", der, &dersize, NULL);
				free(der);
			}
		}

		asn1_delete_structure(&dn);
	}

	return 0;
}