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 1.4 2006/10/24 06:18:42 hsu Exp $ */
3 /* $KAME: in6_cksum.c,v 1.10 2000/12/03 00:53:59 itojun Exp $ */
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62 * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
65 #include <sys/param.h>
67 #include <sys/systm.h>
68 #include <netinet/in.h>
69 #include <netinet/ip6.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 a 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)
104 } ph __attribute__((__packed__));
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 w = (u_int16_t *)&ip6->ip6_src;
128 uph.ph.ph_len = htonl(len);
131 /* IPv6 source address */
133 if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
135 sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
136 sum += w[6]; sum += w[7];
137 /* IPv6 destination address */
139 if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
141 sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13];
142 sum += w[14]; sum += w[15];
143 /* Payload length and upper layer identifier */
144 sum += uph.phs[0]; sum += uph.phs[1];
145 sum += uph.phs[2]; sum += uph.phs[3];
148 * Secondly calculate a summary of the first mbuf excluding offset.
150 while (m != NULL && off > 0) {
157 w = (u_int16_t *)(mtod(m, u_char *) + off);
158 mlen = m->m_len - off;
163 * Force to even boundary.
165 if ((1 & (long) w) && (mlen > 0)) {
168 s_util.c[0] = *(u_char *)w;
169 w = (u_int16_t *)((char *)w + 1);
174 * Unroll the loop to make overhead from
177 while ((mlen -= 32) >= 0) {
178 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
179 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
180 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
181 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
185 while ((mlen -= 8) >= 0) {
186 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
190 if (mlen == 0 && byte_swapped == 0)
193 while ((mlen -= 2) >= 0) {
201 s_util.c[1] = *(char *)w;
206 } else if (mlen == -1)
207 s_util.c[0] = *(char *)w;
212 * Lastly calculate a summary of the rest of mbufs.
215 for (;m && len; m = m->m_next) {
218 w = mtod(m, u_int16_t *);
221 * The first byte of this mbuf is the continuation
222 * of a word spanning between this mbuf and the
225 * s_util.c[0] is already saved when scanning previous
228 s_util.c[1] = *(char *)w;
230 w = (u_int16_t *)((char *)w + 1);
239 * Force to even boundary.
241 if ((1 & (long) w) && (mlen > 0)) {
244 s_util.c[0] = *(u_char *)w;
245 w = (u_int16_t *)((char *)w + 1);
250 * Unroll the loop to make overhead from
253 while ((mlen -= 32) >= 0) {
254 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
255 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
256 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
257 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
261 while ((mlen -= 8) >= 0) {
262 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
266 if (mlen == 0 && byte_swapped == 0)
269 while ((mlen -= 2) >= 0) {
277 s_util.c[1] = *(char *)w;
282 } else if (mlen == -1)
283 s_util.c[0] = *(char *)w;
286 panic("in6_cksum: out of data");
288 /* The last mbuf has odd # of bytes. Follow the
289 standard (the odd byte may be shifted left by 8 bits
290 or not as determined by endian-ness of the machine) */
295 return (~sum & 0xffff);