/*
 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * See the COPYRIGHT file distributed with this work for additional
 * information regarding copyright ownership.
 */

/*! \file */

#include <config.h>

#include <stdbool.h>

#include <isc/assertions.h>
#include <isc/platform.h>
#include <isc/safe.h>
#include <isc/sha1.h>
#include <isc/string.h>
#include <isc/types.h>
#include <isc/util.h>

#if OPENSSL_VERSION_NUMBER < 0x10100000L || defined(LIBRESSL_VERSION_NUMBER)
#define EVP_MD_CTX_new() &(context->_ctx)
#define EVP_MD_CTX_free(ptr) EVP_MD_CTX_cleanup(ptr)
#endif

void
isc_sha1_init(isc_sha1_t *context)
{
	INSIST(context != NULL);

	context->ctx = EVP_MD_CTX_new();
	RUNTIME_CHECK(context->ctx != NULL);
	if (EVP_DigestInit(context->ctx, EVP_sha1()) != 1) {
		FATAL_ERROR(__FILE__, __LINE__, "Cannot initialize SHA1.");
	}
}

void
isc_sha1_invalidate(isc_sha1_t *context) {
	EVP_MD_CTX_free(context->ctx);
	context->ctx = NULL;
}

void
isc_sha1_update(isc_sha1_t *context, const unsigned char *data,
		unsigned int len)
{
	INSIST(context != 0);
	INSIST(context->ctx != 0);
	INSIST(data != 0);

	RUNTIME_CHECK(EVP_DigestUpdate(context->ctx,
				       (const void *) data,
				       (size_t) len) == 1);
}

void
isc_sha1_final(isc_sha1_t *context, unsigned char *digest) {
	INSIST(digest != 0);
	INSIST(context != 0);
	INSIST(context->ctx != 0);

	RUNTIME_CHECK(EVP_DigestFinal(context->ctx, digest, NULL) == 1);
	EVP_MD_CTX_free(context->ctx);
	context->ctx = NULL;
}

/*
 * Check for SHA-1 support; if it does not work, raise a fatal error.
 *
 * Use "a" as the test vector.
 *
 * Standard use is testing false and result true.
 * Testing use is testing true and result false;
 */
bool
isc_sha1_check(bool testing) {
	isc_sha1_t ctx;
	unsigned char input = 'a';
	unsigned char digest[ISC_SHA1_DIGESTLENGTH];
	unsigned char expected[] = {
		0x86, 0xf7, 0xe4, 0x37, 0xfa, 0xa5, 0xa7, 0xfc,
		0xe1, 0x5d, 0x1d, 0xdc, 0xb9, 0xea, 0xea, 0xea,
		0x37, 0x76, 0x67, 0xb8
	};

	INSIST(sizeof(expected) == ISC_SHA1_DIGESTLENGTH);

	/*
	 * Introduce a fault for testing.
	 */
	if (testing) {
		input ^= 0x01;
	}

	/*
	 * These functions do not return anything; any failure will be fatal.
	 */
	isc_sha1_init(&ctx);
	isc_sha1_update(&ctx, &input, 1U);
	isc_sha1_final(&ctx, digest);

	/*
	 * Must return true in standard case, should return false for testing.
	 */
	return (memcmp(digest, expected, ISC_SHA1_DIGESTLENGTH) == 0);
}