220 lines
7.0 KiB
C
220 lines
7.0 KiB
C
/* $OpenBSD: in4_cksum.c,v 1.7 2003/06/02 23:28:13 millert Exp $ */
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/* $KAME: in4_cksum.c,v 1.10 2001/11/30 10:06:15 itojun Exp $ */
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/* $NetBSD: in_cksum.c,v 1.13 1996/10/13 02:03:03 christos Exp $ */
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/*
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* Copyright (C) 1999 WIDE Project.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the project nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Copyright (c) 1988, 1992, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
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*/
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#include <sys/param.h>
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#include <sys/mbuf.h>
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#include <sys/systm.h>
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#include <sys/socket.h>
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#include <net/route.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/ip_var.h>
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/*
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* Checksum routine for Internet Protocol family headers (Portable Version).
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* This is only for IPv4 pseudo header checksum.
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* No need to clear non-pseudo-header fields in IPv4 header.
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* len is for actual payload size, and does not include IPv4 header and
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* skipped header chain (off + len should be equal to the whole packet).
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*
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* This routine is very heavily used in the network
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* code and should be modified for each CPU to be as fast as possible.
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*/
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#define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
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#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
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int
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in4_cksum(m, nxt, off, len)
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struct mbuf *m;
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u_int8_t nxt;
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int off, len;
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{
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u_int16_t *w;
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int sum = 0;
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int mlen = 0;
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int byte_swapped = 0;
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union {
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struct ipovly ipov;
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u_int16_t w[10];
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} u;
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union {
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u_int8_t c[2];
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u_int16_t s;
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} s_util;
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union {
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u_int16_t s[2];
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u_int32_t l;
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} l_util;
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if (nxt != 0) {
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/* pseudo header */
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if (off < sizeof(struct ipovly))
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panic("in4_cksum: offset too short");
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if (m->m_len < sizeof(struct ip))
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panic("in4_cksum: bad mbuf chain");
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bzero(&u.ipov, sizeof(u.ipov));
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u.ipov.ih_len = htons(len);
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u.ipov.ih_pr = nxt;
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u.ipov.ih_src = mtod(m, struct ip *)->ip_src;
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u.ipov.ih_dst = mtod(m, struct ip *)->ip_dst;
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w = u.w;
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/* assumes sizeof(ipov) == 20 */
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sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; sum += w[4];
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sum += w[5]; sum += w[6]; sum += w[7]; sum += w[8]; sum += w[9];
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}
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/* skip unnecessary part */
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while (m && off > 0) {
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if (m->m_len > off)
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break;
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off -= m->m_len;
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m = m->m_next;
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}
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for (;m && len; m = m->m_next) {
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if (m->m_len == 0)
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continue;
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w = (u_int16_t *)(mtod(m, caddr_t) + off);
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if (mlen == -1) {
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/*
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* The first byte of this mbuf is the continuation
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* of a word spanning between this mbuf and the
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* last mbuf.
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*
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* s_util.c[0] is already saved when scanning previous
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* mbuf.
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*/
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s_util.c[1] = *(u_int8_t *)w;
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sum += s_util.s;
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w = (u_int16_t *)((u_int8_t *)w + 1);
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mlen = m->m_len - off - 1;
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len--;
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} else
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mlen = m->m_len - off;
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off = 0;
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if (len < mlen)
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mlen = len;
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len -= mlen;
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/*
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* Force to even boundary.
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*/
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if ((1 & (long) w) && (mlen > 0)) {
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REDUCE;
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sum <<= 8;
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s_util.c[0] = *(u_int8_t *)w;
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w = (u_int16_t *)((int8_t *)w + 1);
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mlen--;
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byte_swapped = 1;
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}
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/*
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* Unroll the loop to make overhead from
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* branches &c small.
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*/
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while ((mlen -= 32) >= 0) {
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sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
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sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
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sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
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sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
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w += 16;
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}
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mlen += 32;
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while ((mlen -= 8) >= 0) {
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sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
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w += 4;
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}
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mlen += 8;
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if (mlen == 0 && byte_swapped == 0)
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continue;
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REDUCE;
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while ((mlen -= 2) >= 0) {
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sum += *w++;
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}
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if (byte_swapped) {
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REDUCE;
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sum <<= 8;
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byte_swapped = 0;
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if (mlen == -1) {
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s_util.c[1] = *(u_int8_t *)w;
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sum += s_util.s;
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mlen = 0;
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} else
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mlen = -1;
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} else if (mlen == -1)
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s_util.c[0] = *(u_int8_t *)w;
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}
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if (len)
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printf("cksum4: out of data\n");
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if (mlen == -1) {
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/* The last mbuf has odd # of bytes. Follow the
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standard (the odd byte may be shifted left by 8 bits
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or not as determined by endian-ness of the machine) */
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s_util.c[1] = 0;
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sum += s_util.s;
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}
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REDUCE;
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return (~sum & 0xffff);
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}
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