2 /* $KAME: in6_cksum.c,v 1.10 2000/12/03 00:53:59 itojun Exp $ */
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61 * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
64 #include <sys/param.h>
66 #include <sys/systm.h>
67 #include <netinet/in.h>
68 #include <netinet/ip6.h>
69 #include <netinet6/scope6_var.h>
71 #include <net/net_osdep.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]; ADDCARRY(sum);}
84 * m MUST contain a continuous 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)
91 in6_cksum(struct mbuf *m, u_int8_t nxt, u_int32_t off, u_int32_t len)
117 if (m->m_pkthdr.len < off + len) {
118 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)",
119 m->m_pkthdr.len, off, len);
122 bzero(&uph, sizeof(uph));
125 * First create IP6 pseudo header and calculate a summary.
127 ip6 = mtod(m, struct ip6_hdr *);
128 uph.ph.ph_len = htonl(len);
132 * IPv6 source address.
133 * XXX: we'd like to avoid copying the address, but we can't due to
134 * the possibly embedded scope zone ID.
137 in6_clearscope(&in6);
138 w = (u_int16_t *)&in6;
139 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
140 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
142 /* IPv6 destination address */
144 in6_clearscope(&in6);
145 w = (u_int16_t *)&in6;
146 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
147 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
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];
154 * Secondly calculate a summary of the first mbuf excluding offset.
156 while (m != NULL && off > 0) {
163 w = (u_int16_t *)(mtod(m, u_char *) + off);
164 mlen = m->m_len - off;
169 * Force to even boundary.
171 if ((1 & (long) w) && (mlen > 0)) {
174 s_util.c[0] = *(u_char *)w;
175 w = (u_int16_t *)((char *)w + 1);
180 * Unroll the loop to make overhead from
183 while ((mlen -= 32) >= 0) {
184 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
185 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
186 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
187 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
191 while ((mlen -= 8) >= 0) {
192 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
196 if (mlen == 0 && byte_swapped == 0)
199 while ((mlen -= 2) >= 0) {
207 s_util.c[1] = *(char *)w;
212 } else if (mlen == -1)
213 s_util.c[0] = *(char *)w;
218 * Lastly calculate a summary of the rest of mbufs.
221 for (;m && len; m = m->m_next) {
224 w = mtod(m, u_int16_t *);
227 * The first byte of this mbuf is the continuation
228 * of a word spanning between this mbuf and the
231 * s_util.c[0] is already saved when scanning previous
234 s_util.c[1] = *(char *)w;
236 w = (u_int16_t *)((char *)w + 1);
245 * Force to even boundary.
247 if ((1 & (long) w) && (mlen > 0)) {
250 s_util.c[0] = *(u_char *)w;
251 w = (u_int16_t *)((char *)w + 1);
256 * Unroll the loop to make overhead from
259 while ((mlen -= 32) >= 0) {
260 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
261 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
262 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
263 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
267 while ((mlen -= 8) >= 0) {
268 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
272 if (mlen == 0 && byte_swapped == 0)
275 while ((mlen -= 2) >= 0) {
283 s_util.c[1] = *(char *)w;
288 } else if (mlen == -1)
289 s_util.c[0] = *(char *)w;
292 panic("in6_cksum: out of data");
294 /* The last mbuf has odd # of bytes. Follow the
295 standard (the odd byte may be shifted left by 8 bits
296 or not as determined by endian-ness of the machine) */
301 return (~sum & 0xffff);