xref: /src/sys/netinet6/in6_cksum.c

/*	$NetBSD: in6_cksum.c,v 1.22 2008/01/25 21:12:15 joerg Exp $	*/
/*	$KAME: in6_cksum.c,v 1.9 2000/09/09 15:33:31 itojun Exp $	*/

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Copyright (c) 1988, 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)in_cksum.c	8.1 (Berkeley) 6/10/93
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: in6_cksum.c,v 1.22 2008/01/25 21:12:15 joerg Exp $");

#include <sys/param.h>
#include <sys/mbuf.h>
#include <sys/systm.h>
#include <netinet/in.h>
#include <netinet/ip6.h>
#include <netinet6/scope6_var.h>

#include <net/net_osdep.h>

/*
 * Checksum routine for Internet Protocol family headers (Portable Version).
 *
 * This routine is very heavily used in the network
 * code and should be modified for each CPU to be as fast as possible.
 */

#define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}

/*
 * m MUST contain a continuous IP6 header.
 * off is a offset where TCP/UDP/ICMP6 header starts.
 * len is a total length of a transport segment.
 * (e.g. TCP header + TCP payload)
 */

int
in6_cksum(struct mbuf *m, u_int8_t nxt, u_int32_t off, u_int32_t len)
{
	u_int16_t *w;
	uint32_t sum = 0;
	struct ip6_hdr *ip6;
	struct in6_addr in6;
	union {
		u_int16_t phs[4];
		struct {
			u_int32_t	ph_len;
			u_int8_t	ph_zero[3];
			u_int8_t	ph_nxt;
		} ph __packed;
	} uph;

	/* sanity check */
	if (m->m_pkthdr.len < off + len) {
		panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)",
			m->m_pkthdr.len, off, len);
	}

	/* Skip pseudo-header if nxt == 0. */
	if (nxt == 0)
		goto skip_phdr;

	bzero(&uph, sizeof(uph));

	/*
	 * First create IP6 pseudo header and calculate a summary.
	 */
	ip6 = mtod(m, struct ip6_hdr *);
	w = (u_int16_t *)&ip6->ip6_src;
	uph.ph.ph_len = htonl(len);
	uph.ph.ph_nxt = nxt;

	/*
	 * IPv6 source address
	 * XXX: we'd like to avoid copying the address, but we can't due to
	 * the possibly embedded scope zone ID.
	 */
	in6 = ip6->ip6_src;
	in6_clearscope(&in6);
	w = (u_int16_t *)&in6;
	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
	sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];

	/* IPv6 destination address */
	in6 = ip6->ip6_dst;
	in6_clearscope(&in6);
	w = (u_int16_t *)&in6;
	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
	sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];

	/* Payload length and upper layer identifier */
	sum += uph.phs[0];  sum += uph.phs[1];
	sum += uph.phs[2];  sum += uph.phs[3];

 skip_phdr:
	return cpu_in_cksum(m, len, off, sum);
}