[apple/xnu.git] / bsd / netinet6 / in6_cksum.c

/*	$FreeBSD: src/sys/netinet6/in6_cksum.c,v 1.1.2.3 2001/07/03 11:01:52 ume Exp $	*/
/*	$KAME: in6_cksum.c,v 1.10 2000/12/03 00:53:59 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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/param.h>
#include <sys/mbuf.h>
#include <sys/systm.h>
#include <kern/debug.h>
#include <netinet/in.h>
#include <netinet/ip6.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)
 */

u_int16_t
inet6_cksum(struct mbuf *m, unsigned int nxt, unsigned int off,
    unsigned int len)
{
	u_int16_t *w;
	int sum = 0;
	int mlen = 0;
	int byte_swapped = 0;
	struct ip6_hdr *ip6;
	union {
		u_int16_t phs[4];
		struct {
			u_int32_t	ph_len;
			u_int8_t	ph_zero[3];
			u_int8_t	ph_nxt;
		} ph __attribute__((__packed__));
	} uph;
	union {
		u_int8_t	c[2];
		u_int16_t	s;
	} s_util;
	union {
		u_int16_t s[2];
		u_int32_t l;
	} l_util;

	/* sanity check */
	if (m->m_pkthdr.len < off + len) {
		panic("inet6_cksum: mbuf len (%d) < off+len (%d+%d)\n",
		    m->m_pkthdr.len, off, len);
	}

	if (nxt != 0) {
		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 */
		sum += w[0];
		if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
			sum += w[1];
		sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
		sum += w[6]; sum += w[7];
		/* IPv6 destination address */
		sum += w[8];
		if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
			sum += w[9];
		sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13];
		sum += w[14]; sum += w[15];
		/* Payload length and upper layer identifier */
		sum += uph.phs[0];  sum += uph.phs[1];
		sum += uph.phs[2];  sum += uph.phs[3];
	}

	/*
	 * Secondly calculate a summary of the first mbuf excluding offset.
	 */
	while (m != NULL && off > 0) {
		if (m->m_len <= off)
			off -= m->m_len;
		else
			break;
		m = m->m_next;
	}
	w = (u_int16_t *)(mtod(m, u_char *) + off);
	mlen = m->m_len - off;
	if (len < mlen)
		mlen = len;
	len -= mlen;
	/*
	 * Force to even boundary.
	 */
	if ((1 & (long) w) && (mlen > 0)) {
		REDUCE;
		sum <<= 8;
		s_util.c[0] = *(u_char *)w;
		w = (u_int16_t *)((char *)w + 1);
		mlen--;
		byte_swapped = 1;
	}
	/*
	 * Unroll the loop to make overhead from
	 * branches &c small.
	 */
	while ((mlen -= 32) >= 0) {
		sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
		sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
		sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
		sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
		w += 16;
	}
	mlen += 32;
	while ((mlen -= 8) >= 0) {
		sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
		w += 4;
	}
	mlen += 8;
	if (mlen == 0 && byte_swapped == 0)
		goto next;
	REDUCE;
	while ((mlen -= 2) >= 0) {
		sum += *w++;
	}
	if (byte_swapped) {
		REDUCE;
		sum <<= 8;
		byte_swapped = 0;
		if (mlen == -1) {
			s_util.c[1] = *(char *)w;
			sum += s_util.s;
			mlen = 0;
		} else
			mlen = -1;
	} else if (mlen == -1)
		s_util.c[0] = *(char *)w;
 next:
	m = m->m_next;

	/*
	 * Lastly calculate a summary of the rest of mbufs.
	 */

	for (;m && len; m = m->m_next) {
		if (m->m_len == 0)
			continue;
		w = mtod(m, u_int16_t *);
		if (mlen == -1) {
			/*
			 * The first byte of this mbuf is the continuation
			 * of a word spanning between this mbuf and the
			 * last mbuf.
			 *
			 * s_util.c[0] is already saved when scanning previous
			 * mbuf.
			 */
			s_util.c[1] = *(char *)w;
			sum += s_util.s;
			w = (u_int16_t *)((char *)w + 1);
			mlen = m->m_len - 1;
			len--;
		} else
			mlen = m->m_len;
		if (len < mlen)
			mlen = len;
		len -= mlen;
		/*
		 * Force to even boundary.
		 */
		if ((1 & (long) w) && (mlen > 0)) {
			REDUCE;
			sum <<= 8;
			s_util.c[0] = *(u_char *)w;
			w = (u_int16_t *)((char *)w + 1);
			mlen--;
			byte_swapped = 1;
		}
		/*
		 * Unroll the loop to make overhead from
		 * branches &c small.
		 */
		while ((mlen -= 32) >= 0) {
			sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
			sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
			sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
			sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
			w += 16;
		}
		mlen += 32;
		while ((mlen -= 8) >= 0) {
			sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
			w += 4;
		}
		mlen += 8;
		if (mlen == 0 && byte_swapped == 0)
			continue;
		REDUCE;
		while ((mlen -= 2) >= 0) {
			sum += *w++;
		}
		if (byte_swapped) {
			REDUCE;
			sum <<= 8;
			byte_swapped = 0;
			if (mlen == -1) {
				s_util.c[1] = *(char *)w;
				sum += s_util.s;
				mlen = 0;
			} else
				mlen = -1;
		} else if (mlen == -1)
			s_util.c[0] = *(char *)w;
	}
	if (len)
		printf("inet6_cksum: out of data by %d\n", len);
	if (mlen == -1) {
		/* The last mbuf has odd # of bytes. Follow the
		   standard (the odd byte may be shifted left by 8 bits
		   or not as determined by endian-ness of the machine) */
		s_util.c[1] = 0;
		sum += s_util.s;
	}
	REDUCE;
	return (~sum & 0xffff);
}
Commit	Line	Data
9bccf70c A	1	/* $FreeBSD: src/sys/netinet6/in6_cksum.c,v 1.1.2.3 2001/07/03 11:01:52 ume Exp $ */
9bccf70c A	2	/* $KAME: in6_cksum.c,v 1.10 2000/12/03 00:53:59 itojun Exp $ */
1c79356b A	3
	4	/*
	5	* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
	6	* All rights reserved.
	7	*
	8	* Redistribution and use in source and binary forms, with or without
	9	* modification, are permitted provided that the following conditions
	10	* are met:
	11	* 1. Redistributions of source code must retain the above copyright
	12	* notice, this list of conditions and the following disclaimer.
	13	* 2. Redistributions in binary form must reproduce the above copyright
	14	* notice, this list of conditions and the following disclaimer in the
	15	* documentation and/or other materials provided with the distribution.
	16	* 3. Neither the name of the project nor the names of its contributors
	17	* may be used to endorse or promote products derived from this software
	18	* without specific prior written permission.
	19	*
	20	* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
	21	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
	24	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	* SUCH DAMAGE.
	31	*/
	32
	33	/*
	34	* Copyright (c) 1988, 1992, 1993
	35	* The Regents of the University of California. All rights reserved.
	36	*
	37	* Redistribution and use in source and binary forms, with or without
	38	* modification, are permitted provided that the following conditions
	39	* are met:
	40	* 1. Redistributions of source code must retain the above copyright
	41	* notice, this list of conditions and the following disclaimer.
	42	* 2. Redistributions in binary form must reproduce the above copyright
	43	* notice, this list of conditions and the following disclaimer in the
	44	* documentation and/or other materials provided with the distribution.
	45	* 3. All advertising materials mentioning features or use of this software
	46	* must display the following acknowledgement:
	47	* This product includes software developed by the University of
	48	* California, Berkeley and its contributors.
	49	* 4. Neither the name of the University nor the names of its contributors
	50	* may be used to endorse or promote products derived from this software
	51	* without specific prior written permission.
	52	*
	53	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	54	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	55	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	56	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	57	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	58	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	59	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	60	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	61	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	62	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	63	* SUCH DAMAGE.
	64	*
	65	* @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
	66	*/
67
68	#include <sys/param.h>
69	#include <sys/mbuf.h>
70	#include <sys/systm.h>
2d21ac55	71	#include <kern/debug.h>
1c79356b A	72	#include <netinet/in.h>
	73	#include <netinet/ip6.h>
	74
	75	#include <net/net_osdep.h>
	76
	77	/*
	78	* Checksum routine for Internet Protocol family headers (Portable Version).
	79	*
	80	* This routine is very heavily used in the network
	81	* code and should be modified for each CPU to be as fast as possible.
	82	*/
	83
	84	#define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
	85	#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
	86
1c79356b A	87	/*
	88	* m MUST contain a continuous IP6 header.
	89	* off is a offset where TCP/UDP/ICMP6 header starts.
	90	* len is a total length of a transport segment.
	91	* (e.g. TCP header + TCP payload)
	92	*/
	93
2d21ac55 A	94	u_int16_t
	95	inet6_cksum(struct mbuf *m, unsigned int nxt, unsigned int off,
	96	unsigned int len)
1c79356b	97	{
9bccf70c A	98	u_int16_t *w;
	99	int sum = 0;
	100	int mlen = 0;
1c79356b	101	int byte_swapped = 0;
2d21ac55	102	struct ip6_hdr *ip6;
9bccf70c A	103	union {
	104	u_int16_t phs[4];
	105	struct {
	106	u_int32_t ph_len;
	107	u_int8_t ph_zero[3];
	108	u_int8_t ph_nxt;
	109	} ph __attribute__((__packed__));
	110	} uph;
1c79356b A	111	union {
	112	u_int8_t c[2];
	113	u_int16_t s;
	114	} s_util;
	115	union {
	116	u_int16_t s[2];
	117	u_int32_t l;
	118	} l_util;
	119
	120	/* sanity check */
	121	if (m->m_pkthdr.len < off + len) {
2d21ac55 A	122	panic("inet6_cksum: mbuf len (%d) < off+len (%d+%d)\n",
2d21ac55 A	123	m->m_pkthdr.len, off, len);
1c79356b A	124	}
1c79356b A	125
2d21ac55 A	126	if (nxt != 0) {
2d21ac55 A	127	bzero(&uph, sizeof (uph));
9bccf70c	128
2d21ac55 A	129	/*
	130	* First create IP6 pseudo header and calculate a summary.
	131	*/
	132	ip6 = mtod(m, struct ip6_hdr *);
	133	w = (u_int16_t *)&ip6->ip6_src;
	134	uph.ph.ph_len = htonl(len);
	135	uph.ph.ph_nxt = nxt;
1c79356b	136
2d21ac55 A	137	/* IPv6 source address */
	138	sum += w[0];
	139	if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
	140	sum += w[1];
	141	sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
	142	sum += w[6]; sum += w[7];
	143	/* IPv6 destination address */
	144	sum += w[8];
	145	if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
	146	sum += w[9];
	147	sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13];
	148	sum += w[14]; sum += w[15];
	149	/* Payload length and upper layer identifier */
	150	sum += uph.phs[0]; sum += uph.phs[1];
	151	sum += uph.phs[2]; sum += uph.phs[3];
	152	}
1c79356b	153
1c79356b A	154	/*
	155	* Secondly calculate a summary of the first mbuf excluding offset.
	156	*/
	157	while (m != NULL && off > 0) {
	158	if (m->m_len <= off)
	159	off -= m->m_len;
	160	else
	161	break;
	162	m = m->m_next;
	163	}
	164	w = (u_int16_t )(mtod(m, u_char ) + off);
	165	mlen = m->m_len - off;
	166	if (len < mlen)
	167	mlen = len;
	168	len -= mlen;
	169	/*
	170	* Force to even boundary.
	171	*/
	172	if ((1 & (long) w) && (mlen > 0)) {
	173	REDUCE;
	174	sum <<= 8;
	175	s_util.c[0] = (u_char )w;
	176	w = (u_int16_t )((char )w + 1);
	177	mlen--;
	178	byte_swapped = 1;
	179	}
	180	/*
	181	* Unroll the loop to make overhead from
	182	* branches &c small.
	183	*/
	184	while ((mlen -= 32) >= 0) {
	185	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
	186	sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
	187	sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
	188	sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
	189	w += 16;
	190	}
	191	mlen += 32;
	192	while ((mlen -= 8) >= 0) {
	193	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
	194	w += 4;
	195	}
	196	mlen += 8;
	197	if (mlen == 0 && byte_swapped == 0)
	198	goto next;
	199	REDUCE;
	200	while ((mlen -= 2) >= 0) {
	201	sum += *w++;
	202	}
	203	if (byte_swapped) {
	204	REDUCE;
	205	sum <<= 8;
	206	byte_swapped = 0;
	207	if (mlen == -1) {
	208	s_util.c[1] = (char )w;
	209	sum += s_util.s;
	210	mlen = 0;
	211	} else
	212	mlen = -1;
	213	} else if (mlen == -1)
	214	s_util.c[0] = (char )w;
	215	next:
	216	m = m->m_next;
	217
218	/*
219	* Lastly calculate a summary of the rest of mbufs.
220	*/
2d21ac55	221
1c79356b A	222	for (;m && len; m = m->m_next) {
	223	if (m->m_len == 0)
	224	continue;
	225	w = mtod(m, u_int16_t *);
	226	if (mlen == -1) {
	227	/*
	228	* The first byte of this mbuf is the continuation
	229	* of a word spanning between this mbuf and the
	230	* last mbuf.
	231	*
	232	* s_util.c[0] is already saved when scanning previous
	233	* mbuf.
	234	*/
	235	s_util.c[1] = (char )w;
	236	sum += s_util.s;
	237	w = (u_int16_t )((char )w + 1);
	238	mlen = m->m_len - 1;
	239	len--;
	240	} else
	241	mlen = m->m_len;
	242	if (len < mlen)
	243	mlen = len;
	244	len -= mlen;
	245	/*
	246	* Force to even boundary.
	247	*/
	248	if ((1 & (long) w) && (mlen > 0)) {
	249	REDUCE;
	250	sum <<= 8;
	251	s_util.c[0] = (u_char )w;
	252	w = (u_int16_t )((char )w + 1);
	253	mlen--;
	254	byte_swapped = 1;
	255	}
	256	/*
	257	* Unroll the loop to make overhead from
	258	* branches &c small.
	259	*/
	260	while ((mlen -= 32) >= 0) {
	261	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
	262	sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
	263	sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
	264	sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
	265	w += 16;
	266	}
	267	mlen += 32;
	268	while ((mlen -= 8) >= 0) {
	269	sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
	270	w += 4;
	271	}
	272	mlen += 8;
	273	if (mlen == 0 && byte_swapped == 0)
	274	continue;
	275	REDUCE;
	276	while ((mlen -= 2) >= 0) {
	277	sum += *w++;
	278	}
	279	if (byte_swapped) {
	280	REDUCE;
	281	sum <<= 8;
	282	byte_swapped = 0;
	283	if (mlen == -1) {
	284	s_util.c[1] = (char )w;
	285	sum += s_util.s;
286	mlen = 0;
287	} else
288	mlen = -1;
289	} else if (mlen == -1)
290	s_util.c[0] = (char )w;
291	}
292	if (len)
2d21ac55	293	printf("inet6_cksum: out of data by %d\n", len);
1c79356b A	294	if (mlen == -1) {
	295	/* The last mbuf has odd # of bytes. Follow the
	296	standard (the odd byte may be shifted left by 8 bits
	297	or not as determined by endian-ness of the machine) */
	298	s_util.c[1] = 0;
	299	sum += s_util.s;
	300	}
	301	REDUCE;
	302	return (~sum & 0xffff);
	303	}