2 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
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25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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29 * $KAME: in6_cksum.c,v 1.10 2000/12/03 00:53:59 itojun Exp $
33 * Copyright (c) 1988, 1992, 1993
34 * The Regents of the University of California. All rights reserved.
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37 * modification, are permitted provided that the following conditions
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40 * notice, this list of conditions and the following disclaimer.
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45 * may be used to endorse or promote products derived from this software
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49 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
50 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
51 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
52 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
53 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
54 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
55 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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60 * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
63 #include <sys/cdefs.h>
64 __FBSDID("$FreeBSD$");
66 #include <sys/param.h>
68 #include <sys/systm.h>
69 #include <netinet/in.h>
70 #include <netinet/ip6.h>
71 #include <netinet6/scope6_var.h>
74 * Checksum routine for Internet Protocol family headers (Portable Version).
76 * This routine is very heavily used in the network
77 * code and should be modified for each CPU to be as fast as possible.
80 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
81 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; (void)ADDCARRY(sum);}
84 * m MUST contain a contiguous IP6 header.
85 * off is an offset where TCP/UDP/ICMP6 header starts.
86 * len is a total length of a transport segment.
87 * (e.g. TCP header + TCP payload)
90 in6_cksum(struct mbuf *m, u_int8_t nxt, u_int32_t off, u_int32_t len)
116 if (m->m_pkthdr.len < off + len) {
117 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)",
118 m->m_pkthdr.len, off, len);
121 bzero(&uph, sizeof(uph));
124 * First create IP6 pseudo header and calculate a summary.
126 ip6 = mtod(m, struct ip6_hdr *);
127 uph.ph.ph_len = htonl(len);
131 * IPv6 source address.
132 * XXX: we'd like to avoid copying the address, but we can't due to
133 * the possibly embedded scope zone ID.
136 in6_clearscope(&in6);
137 w = (u_int16_t *)&in6;
138 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
139 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
141 /* IPv6 destination address */
143 in6_clearscope(&in6);
144 w = (u_int16_t *)&in6;
145 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
146 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
148 /* Payload length and upper layer identifier */
149 sum += uph.phs[0]; sum += uph.phs[1];
150 sum += uph.phs[2]; sum += uph.phs[3];
153 * Secondly calculate a summary of the first mbuf excluding offset.
162 w = (u_int16_t *)(mtod(m, u_char *) + off);
163 mlen = m->m_len - off;
168 * Force to even boundary.
170 if ((1 & (long) w) && (mlen > 0)) {
173 s_util.c[0] = *(u_char *)w;
174 w = (u_int16_t *)((char *)w + 1);
179 * Unroll the loop to make overhead from
182 while ((mlen -= 32) >= 0) {
183 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
184 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
185 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
186 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
190 while ((mlen -= 8) >= 0) {
191 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
195 if (mlen == 0 && byte_swapped == 0)
198 while ((mlen -= 2) >= 0) {
206 s_util.c[1] = *(char *)w;
211 } else if (mlen == -1)
212 s_util.c[0] = *(char *)w;
217 * Lastly calculate a summary of the rest of mbufs.
220 for (;m && len; m = m->m_next) {
223 w = mtod(m, u_int16_t *);
226 * The first byte of this mbuf is the continuation
227 * of a word spanning between this mbuf and the
230 * s_util.c[0] is already saved when scanning previous
233 s_util.c[1] = *(char *)w;
235 w = (u_int16_t *)((char *)w + 1);
244 * Force to even boundary.
246 if ((1 & (long) w) && (mlen > 0)) {
249 s_util.c[0] = *(u_char *)w;
250 w = (u_int16_t *)((char *)w + 1);
255 * Unroll the loop to make overhead from
258 while ((mlen -= 32) >= 0) {
259 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
260 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
261 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
262 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
266 while ((mlen -= 8) >= 0) {
267 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
271 if (mlen == 0 && byte_swapped == 0)
274 while ((mlen -= 2) >= 0) {
282 s_util.c[1] = *(char *)w;
287 } else if (mlen == -1)
288 s_util.c[0] = *(char *)w;
291 panic("in6_cksum: out of data");
293 /* The last mbuf has odd # of bytes. Follow the
294 standard (the odd byte may be shifted left by 8 bits
295 or not as determined by endian-ness of the machine) */
300 return (~sum & 0xffff);