1 /* $FreeBSD: src/sys/netinet6/in6_cksum.c,v 1.1.2.4 2003/05/06 06:46:58 suz Exp $ */
2 /* $DragonFly: src/sys/netinet6/in6_cksum.c,v 1.2 2003/06/17 04:28:52 dillon Exp $ */
3 /* $KAME: in6_cksum.c,v 1.10 2000/12/03 00:53:59 itojun Exp $ */
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66 * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
69 #include <sys/param.h>
71 #include <sys/systm.h>
72 #include <netinet/in.h>
73 #include <netinet/ip6.h>
75 #include <net/net_osdep.h>
78 * Checksum routine for Internet Protocol family headers (Portable Version).
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.
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);}
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)
95 in6_cksum(m, nxt, off, len)
103 int byte_swapped = 0;
105 int srcifid = 0, dstifid = 0;
114 } ph __attribute__((__packed__));
126 if (m->m_pkthdr.len < off + len) {
127 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)",
128 m->m_pkthdr.len, off, len);
131 bzero(&uph, sizeof(uph));
134 * First create IP6 pseudo header and calculate a summary.
136 ip6 = mtod(m, struct ip6_hdr *);
138 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) {
139 srcifid = ip6->ip6_src.s6_addr16[1];
140 ip6->ip6_src.s6_addr16[1] = 0;
142 if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) {
143 dstifid = ip6->ip6_dst.s6_addr16[1];
144 ip6->ip6_dst.s6_addr16[1] = 0;
147 w = (u_int16_t *)&ip6->ip6_src;
148 uph.ph.ph_len = htonl(len);
151 /* IPv6 source address */
153 if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
155 sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
156 sum += w[6]; sum += w[7];
157 /* IPv6 destination address */
159 if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
161 sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13];
162 sum += w[14]; sum += w[15];
163 /* Payload length and upper layer identifier */
164 sum += uph.phs[0]; sum += uph.phs[1];
165 sum += uph.phs[2]; sum += uph.phs[3];
169 ip6->ip6_src.s6_addr16[1] = srcifid;
171 ip6->ip6_dst.s6_addr16[1] = dstifid;
174 * Secondly calculate a summary of the first mbuf excluding offset.
176 while (m != NULL && off > 0) {
183 w = (u_int16_t *)(mtod(m, u_char *) + off);
184 mlen = m->m_len - off;
189 * Force to even boundary.
191 if ((1 & (long) w) && (mlen > 0)) {
194 s_util.c[0] = *(u_char *)w;
195 w = (u_int16_t *)((char *)w + 1);
200 * Unroll the loop to make overhead from
203 while ((mlen -= 32) >= 0) {
204 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
205 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
206 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
207 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
211 while ((mlen -= 8) >= 0) {
212 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
216 if (mlen == 0 && byte_swapped == 0)
219 while ((mlen -= 2) >= 0) {
227 s_util.c[1] = *(char *)w;
232 } else if (mlen == -1)
233 s_util.c[0] = *(char *)w;
238 * Lastly calculate a summary of the rest of mbufs.
241 for (;m && len; m = m->m_next) {
244 w = mtod(m, u_int16_t *);
247 * The first byte of this mbuf is the continuation
248 * of a word spanning between this mbuf and the
251 * s_util.c[0] is already saved when scanning previous
254 s_util.c[1] = *(char *)w;
256 w = (u_int16_t *)((char *)w + 1);
265 * Force to even boundary.
267 if ((1 & (long) w) && (mlen > 0)) {
270 s_util.c[0] = *(u_char *)w;
271 w = (u_int16_t *)((char *)w + 1);
276 * Unroll the loop to make overhead from
279 while ((mlen -= 32) >= 0) {
280 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
281 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
282 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
283 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
287 while ((mlen -= 8) >= 0) {
288 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
292 if (mlen == 0 && byte_swapped == 0)
295 while ((mlen -= 2) >= 0) {
303 s_util.c[1] = *(char *)w;
308 } else if (mlen == -1)
309 s_util.c[0] = *(char *)w;
312 panic("in6_cksum: out of data");
314 /* The last mbuf has odd # of bytes. Follow the
315 standard (the odd byte may be shifted left by 8 bits
316 or not as determined by endian-ness of the machine) */
321 return (~sum & 0xffff);