/*

 * CDDL HEADER START

 *

 * The contents of this file are subject to the terms of the

 * Common Development and Distribution License (the "License").

 * You may not use this file except in compliance with the License.

 *

 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE

 * or http://www.opensolaris.org/os/licensing.

 * See the License for the specific language governing permissions

 * and limitations under the License.

 *

 * When distributing Covered Code, include this CDDL HEADER in each

 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.

 * If applicable, add the following below this CDDL HEADER, with the

 * fields enclosed by brackets "[]" replaced with your own identifying

 * information: Portions Copyright [yyyy] [name of copyright owner]

 *

 * CDDL HEADER END

 */

/*

 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.

 * Use is subject to license terms.

 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

#include <sys/zfs_context.h>

#include <sys/spa.h>

#include <sys/zio.h>

#include <sys/zio_checksum.h>

/*

 * Checksum vectors.

 *

 * In the SPA, everything is checksummed.  We support checksum vectors

 * for three distinct reasons:

 *

 *   1. Different kinds of data need different levels of protection.

 *	For SPA metadata, we always want a very strong checksum.

 *	For user data, we let users make the trade-off between speed

 *	and checksum strength.

 *

 *   2. Cryptographic hash and MAC algorithms are an area of active research.

 *	It is likely that in future hash functions will be at least as strong

 *	as current best-of-breed, and may be substantially faster as well.

 *	We want the ability to take advantage of these new hashes as soon as

 *	they become available.

 *

 *   3. If someone develops hardware that can compute a strong hash quickly,

 *	we want the ability to take advantage of that hardware.

 *

 * Of course, we don't want a checksum upgrade to invalidate existing

 * data, so we store the checksum *function* in five bits of the DVA.

 * This gives us room for up to 32 different checksum functions.

 *

 * When writing a block, we always checksum it with the latest-and-greatest

 * checksum function of the appropriate strength.  When reading a block,

 * we compare the expected checksum against the actual checksum, which we

 * compute via the checksum function specified in the DVA encoding.

 */

/*ARGSUSED*/

static void

zio_checksum_off(const void *buf, uint64_t size, zio_cksum_t *zcp)

{

	ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);

}

zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = {

	{{NULL,			NULL},			0, 0,	"inherit"},

	{{NULL,			NULL},			0, 0,	"on"},

	{{zio_checksum_off,	zio_checksum_off},	0, 0,	"off"},

	{{zio_checksum_SHA256,	zio_checksum_SHA256},	1, 1,	"label"},

	{{zio_checksum_SHA256,	zio_checksum_SHA256},	1, 1,	"gang_header"},

	{{fletcher_2_native,	fletcher_2_byteswap},	0, 1,	"zilog"},

	{{fletcher_2_native,	fletcher_2_byteswap},	0, 0,	"fletcher2"},

	{{fletcher_4_native,	fletcher_4_byteswap},	1, 0,	"fletcher4"},

	{{zio_checksum_SHA256,	zio_checksum_SHA256},	1, 0,	"SHA256"},

};

uint8_t

zio_checksum_select(uint8_t child, uint8_t parent)

{

	ASSERT(child < ZIO_CHECKSUM_FUNCTIONS);

	ASSERT(parent < ZIO_CHECKSUM_FUNCTIONS);

	ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON);

	if (child == ZIO_CHECKSUM_INHERIT)

		return (parent);

	if (child == ZIO_CHECKSUM_ON)

		return (ZIO_CHECKSUM_ON_VALUE);

	return (child);

}

/*

 * Generate the checksum.

 */

void

zio_checksum(uint_t checksum, zio_cksum_t *zcp, void *data, uint64_t size)

{

	zio_block_tail_t *zbt = (zio_block_tail_t *)((char *)data + size) - 1;

	zio_checksum_info_t *ci = &zio_checksum_table[checksum];

	zio_cksum_t zbt_cksum;

	ASSERT(checksum < ZIO_CHECKSUM_FUNCTIONS);

	ASSERT(ci->ci_func[0] != NULL);

	if (ci->ci_zbt) {

		*zcp = zbt->zbt_cksum;

		zbt->zbt_magic = ZBT_MAGIC;

		ci->ci_func[0](data, size, &zbt_cksum);

		zbt->zbt_cksum = zbt_cksum;

	} else {

		ci->ci_func[0](data, size, zcp);

	}

}

int

zio_checksum_error(zio_t *zio)

{

	blkptr_t *bp = zio->io_bp;

	zio_cksum_t zc = bp->blk_cksum;

	uint_t checksum = BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER :

	    BP_GET_CHECKSUM(bp);

	int byteswap = BP_SHOULD_BYTESWAP(bp);

	void *data = zio->io_data;

	uint64_t size = ZIO_GET_IOSIZE(zio);

	zio_block_tail_t *zbt = (zio_block_tail_t *)((char *)data + size) - 1;

	zio_checksum_info_t *ci = &zio_checksum_table[checksum];

	zio_cksum_t actual_cksum, expected_cksum;

	if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL)

		return (EINVAL);

	if (ci->ci_zbt) {

		if (checksum == ZIO_CHECKSUM_GANG_HEADER)

			zio_set_gang_verifier(zio, &zc);

		if (zbt->zbt_magic == BSWAP_64(ZBT_MAGIC)) {

			expected_cksum = zbt->zbt_cksum;

			byteswap_uint64_array(&expected_cksum,

			    sizeof (zio_cksum_t));

			zbt->zbt_cksum = zc;

			byteswap_uint64_array(&zbt->zbt_cksum,

			    sizeof (zio_cksum_t));

			ci->ci_func[1](data, size, &actual_cksum);

			zbt->zbt_cksum = expected_cksum;

			byteswap_uint64_array(&zbt->zbt_cksum,

			    sizeof (zio_cksum_t));

		} else {

			expected_cksum = zbt->zbt_cksum;

			zbt->zbt_cksum = zc;

			ci->ci_func[0](data, size, &actual_cksum);

			zbt->zbt_cksum = expected_cksum;

		}

		zc = expected_cksum;

	} else {

		ASSERT(!BP_IS_GANG(bp));

		ci->ci_func[byteswap](data, size, &actual_cksum);

	}

	if (!ZIO_CHECKSUM_EQUAL(actual_cksum, zc))

		return (ECKSUM);

	if (zio_injection_enabled && !zio->io_error)

		return (zio_handle_fault_injection(zio, ECKSUM));

	return (0);

}