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>
72 * Checksum routine for Internet Protocol family headers (Portable Version).
74 * This routine is very heavily used in the network
75 * code and should be modified for each CPU to be as fast as possible.
78 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
79 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
82 * m MUST contain a continuous IP6 header.
83 * off is an offset where TCP/UDP/ICMP6 header starts.
84 * len is a total length of a transport segment.
85 * (e.g. TCP header + TCP payload)
89 in6_cksum(struct mbuf *m, u_int8_t nxt, u_int32_t off, u_int32_t len)
115 if (m->m_pkthdr.len < off + len) {
116 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)",
117 m->m_pkthdr.len, off, len);
120 bzero(&uph, sizeof(uph));
123 * First create IP6 pseudo header and calculate a summary.
125 ip6 = mtod(m, struct ip6_hdr *);
126 uph.ph.ph_len = htonl(len);
130 * IPv6 source address.
131 * XXX: we'd like to avoid copying the address, but we can't due to
132 * the possibly embedded scope zone ID.
135 in6_clearscope(&in6);
136 w = (u_int16_t *)&in6;
137 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
138 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
140 /* IPv6 destination address */
142 in6_clearscope(&in6);
143 w = (u_int16_t *)&in6;
144 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
145 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
147 /* Payload length and upper layer identifier */
148 sum += uph.phs[0]; sum += uph.phs[1];
149 sum += uph.phs[2]; sum += uph.phs[3];
152 * Secondly calculate a summary of the first mbuf excluding offset.
161 w = (u_int16_t *)(mtod(m, u_char *) + off);
162 mlen = m->m_len - off;
167 * Force to even boundary.
169 if ((1 & (long) w) && (mlen > 0)) {
172 s_util.c[0] = *(u_char *)w;
173 w = (u_int16_t *)((char *)w + 1);
178 * Unroll the loop to make overhead from
181 while ((mlen -= 32) >= 0) {
182 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
183 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
184 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
185 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
189 while ((mlen -= 8) >= 0) {
190 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
194 if (mlen == 0 && byte_swapped == 0)
197 while ((mlen -= 2) >= 0) {
205 s_util.c[1] = *(char *)w;
210 } else if (mlen == -1)
211 s_util.c[0] = *(char *)w;
216 * Lastly calculate a summary of the rest of mbufs.
219 for (;m && len; m = m->m_next) {
222 w = mtod(m, u_int16_t *);
225 * The first byte of this mbuf is the continuation
226 * of a word spanning between this mbuf and the
229 * s_util.c[0] is already saved when scanning previous
232 s_util.c[1] = *(char *)w;
234 w = (u_int16_t *)((char *)w + 1);
243 * Force to even boundary.
245 if ((1 & (long) w) && (mlen > 0)) {
248 s_util.c[0] = *(u_char *)w;
249 w = (u_int16_t *)((char *)w + 1);
254 * Unroll the loop to make overhead from
257 while ((mlen -= 32) >= 0) {
258 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
259 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
260 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
261 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
265 while ((mlen -= 8) >= 0) {
266 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
270 if (mlen == 0 && byte_swapped == 0)
273 while ((mlen -= 2) >= 0) {
281 s_util.c[1] = *(char *)w;
286 } else if (mlen == -1)
287 s_util.c[0] = *(char *)w;
290 panic("in6_cksum: out of data");
292 /* The last mbuf has odd # of bytes. Follow the
293 standard (the odd byte may be shifted left by 8 bits
294 or not as determined by endian-ness of the machine) */
299 return (~sum & 0xffff);