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File: [cvs.NetBSD.org] / src / sys / netinet / in4_cksum.c (download)

Revision 1.17, Tue Feb 12 13:05:55 2008 UTC (10 years, 8 months ago) by joerg
Branch: MAIN
CVS Tags: yamt-pf42-baseX, yamt-pf42-base4, yamt-pf42-base3, yamt-pf42-base2, yamt-pf42-base, yamt-pf42, yamt-nfs-mp-base9, yamt-nfs-mp-base8, yamt-nfs-mp-base7, yamt-nfs-mp-base6, yamt-nfs-mp-base5, yamt-nfs-mp-base4, yamt-nfs-mp-base3, yamt-nfs-mp-base2, yamt-nfs-mp-base11, yamt-nfs-mp-base10, yamt-nfs-mp-base, yamt-nfs-mp, yamt-lazymbuf-base15, yamt-lazymbuf-base14, wrstuden-revivesa-base-4, wrstuden-revivesa-base-3, wrstuden-revivesa-base-2, wrstuden-revivesa-base-1, wrstuden-revivesa-base, wrstuden-revivesa, uebayasi-xip-base4, uebayasi-xip-base3, uebayasi-xip-base2, uebayasi-xip-base1, uebayasi-xip-base, uebayasi-xip, simonb-wapbl-nbase, simonb-wapbl-base, simonb-wapbl, nick-net80211-sync-base, nick-net80211-sync, nick-hppapmap-base4, nick-hppapmap-base3, nick-hppapmap-base2, nick-hppapmap-base, nick-hppapmap, netbsd-5-base, netbsd-5-2-RELEASE, netbsd-5-2-RC1, netbsd-5-2-3-RELEASE, netbsd-5-2-2-RELEASE, netbsd-5-2-1-RELEASE, netbsd-5-2, netbsd-5-1-RELEASE, netbsd-5-1-RC4, netbsd-5-1-RC3, netbsd-5-1-RC2, netbsd-5-1-RC1, netbsd-5-1-5-RELEASE, netbsd-5-1-4-RELEASE, netbsd-5-1-3-RELEASE, netbsd-5-1-2-RELEASE, netbsd-5-1-1-RELEASE, netbsd-5-1, netbsd-5-0-RELEASE, netbsd-5-0-RC4, netbsd-5-0-RC3, netbsd-5-0-RC2, netbsd-5-0-RC1, netbsd-5-0-2-RELEASE, netbsd-5-0-1-RELEASE, netbsd-5-0, netbsd-5, mjf-devfs2-base, mjf-devfs2, mjf-devfs-base, matt-premerge-20091211, matt-nb5-pq3-base, matt-nb5-pq3, matt-nb5-mips64-u2-k2-k4-k7-k8-k9, matt-nb5-mips64-u1-k1-k5, matt-nb5-mips64-premerge-20101231, matt-nb5-mips64-premerge-20091211, matt-nb5-mips64-k15, matt-nb5-mips64, matt-nb4-mips64-k7-u2a-k9b, matt-mips64-premerge-20101231, matt-mips64-base2, matt-armv6-nbase, keiichi-mipv6-nbase, keiichi-mipv6-base, keiichi-mipv6, jymxensuspend-base, jym-xensuspend-nbase, jym-xensuspend-base, jym-xensuspend, jruoho-x86intr-base, hpcarm-cleanup-nbase, hpcarm-cleanup-base, haad-nbase2, haad-dm-base2, haad-dm-base1, haad-dm-base, haad-dm, bouyer-quota2-nbase, bouyer-quota2-base, bouyer-quota2, ad-socklock-base1, ad-audiomp2-base, ad-audiomp2
Branch point for: rmind-uvmplock, jruoho-x86intr
Changes since 1.16: +4 -4 lines

Explicitly predict panic conditions as false.

/*	$NetBSD: in4_cksum.c,v 1.17 2008/02/12 13:05:55 joerg Exp $	*/

/*-
 * Copyright (c) 2008 Joerg Sonnenberger <joerg@NetBSD.org>.
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
 * COPYRIGHT HOLDERS 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: in4_cksum.c,v 1.17 2008/02/12 13:05:55 joerg Exp $");

#include <sys/param.h>
#include <sys/mbuf.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>

/*
 * Checksum of the IPv4 pseudo header.
 *
 * off is supposed to be the skipped IPv4 header, len is the payload size.
 */

int
in4_cksum(struct mbuf *m, u_int8_t nxt, int off, int len)
{
	uint32_t sum;
	uint16_t *w;

	if (__predict_false(off < sizeof(struct ip)))
		panic("in4_cksum: offset too short for IP header");
	if (__predict_false(m->m_len < sizeof(struct ip)))
		panic("in4_cksum: mbuf too short for IP header");

	if (nxt == 0)
		return cpu_in_cksum(m, len, off, 0);

	/*
	 * Compute the equivalent of:
	 * struct ipovly ip;
	 *
	 * bzero(sizeof(*ip));
	 * ip.ih_pr = nxt;
	 * ip.ip_len = htons(len);
	 * ip.ih_src = mtod(m, struct ip *)->ip_src;
	 * ip.ih_dst = mtod(m, struct ip *)->ip_dst;
	 * sum = one_add(&ip);
	 */

#if BYTE_ORDER == LITTLE_ENDIAN
	sum = ((len & 0xffff) + nxt) << 8;
#else
	sum = (len & 0xffff) + nxt;
#endif
	w = (uint16_t *)(mtod(m, char  *) + offsetof(struct ip, ip_src));
	if (__predict_true((uintptr_t)w % 2 == 0)) {
		sum += w[0];
		sum += w[1];
		sum += w[2];
		sum += w[3];
	} else {
		uint32_t partial;
		w = (void *)((uintptr_t)w - 1);
#if BYTE_ORDER == LITTLE_ENDIAN
		partial = w[0] & 0xff00;
#else
		partial = w[0] & 0x00ff;
#endif
		partial += w[1];
		partial += w[2];
		partial += w[3];
#if BYTE_ORDER == LITTLE_ENDIAN
		partial += w[4] & 0x00ff;
#else
		partial += w[4] & 0xff00;
#endif
		sum += partial << 8;
	}

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