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31 * $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/cdefs.h>
66 __FBSDID("$FreeBSD$");
68 #include <sys/param.h>
70 #include <sys/systm.h>
71 #include <netinet/in.h>
72 #include <netinet/ip6.h>
73 #include <netinet6/scope6_var.h>
76 * Checksum routine for Internet Protocol family headers (Portable Version).
78 * This routine is very heavily used in the network
79 * code and should be modified for each CPU to be as fast as possible.
82 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
83 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; (void)ADDCARRY(sum);}
96 _in6_cksum_pseudo(struct ip6_hdr *ip6, uint32_t len, uint8_t nxt, uint16_t csum)
112 * First create IP6 pseudo header and calculate a summary.
114 uph.ph.ph_len = htonl(len);
115 uph.ph.ph_zero[0] = uph.ph.ph_zero[1] = uph.ph.ph_zero[2] = 0;
118 /* Payload length and upper layer identifier. */
119 sum += uph.phs[0]; sum += uph.phs[1];
120 sum += uph.phs[2]; sum += uph.phs[3];
122 /* IPv6 source address. */
123 scope = in6_getscope(&ip6->ip6_src);
124 w = (u_int16_t *)&ip6->ip6_src;
125 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
126 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
130 /* IPv6 destination address. */
131 scope = in6_getscope(&ip6->ip6_dst);
132 w = (u_int16_t *)&ip6->ip6_dst;
133 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
134 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
142 in6_cksum_pseudo(struct ip6_hdr *ip6, uint32_t len, uint8_t nxt, uint16_t csum)
147 sum = _in6_cksum_pseudo(ip6, len, nxt, csum);
153 in6_cksumdata(void *data, int *lenp, uint8_t *residp, int rlen)
161 KASSERT(*lenp >= 0, ("%s: negative len %d", __func__, *lenp));
162 KASSERT(rlen == 0 || rlen == 1, ("%s: rlen %d", __func__, rlen));
172 byte_swapped = false;
176 * Do we have a residual byte left over from the previous buffer?
179 s_util.c[0] = *residp;
180 s_util.c[1] = *(uint8_t *)w;
182 w = (uint16_t *)((uint8_t *)w + 1);
188 * Force to even boundary.
190 if ((1 & (uintptr_t)w) && len > 0) {
193 s_util.c[0] = *(uint8_t *)w;
194 w = (uint16_t *)((uint8_t *)w + 1);
200 * Unroll the loop to make overhead from branches &c small.
202 while ((len -= 32) >= 0) {
203 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
204 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
205 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
206 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
210 while ((len -= 8) >= 0) {
211 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
215 if (len == 0 && !byte_swapped)
218 while ((len -= 2) >= 0) {
225 s_util.c[1] = *(uint8_t *)w;
227 } else /* len == -2 */
228 *residp = s_util.c[0];
230 } else if (len == -1)
231 *residp = *(uint8_t *)w;
237 struct in6_cksum_partial_arg {
244 in6_cksum_partial_one(void *_arg, void *data, u_int len)
246 struct in6_cksum_partial_arg *arg = _arg;
248 arg->sum += in6_cksumdata(data, &len, &arg->resid, arg->rlen);
254 * m MUST contain a contiguous IP6 header.
255 * off is an offset where TCP/UDP/ICMP6 header starts.
256 * len is a total length of a transport segment.
257 * (e.g. TCP header + TCP payload)
258 * cov is the number of bytes to be taken into account for the checksum
261 in6_cksum_partial(struct mbuf *m, uint8_t nxt, uint32_t off, uint32_t len,
264 struct in6_cksum_partial_arg arg;
280 KASSERT(m->m_pkthdr.len >= off + len, ("%s: mbuf len (%d) < off(%d)+"
281 "len(%d)", __func__, m->m_pkthdr.len, off, len));
282 KASSERT(m->m_len >= sizeof(*ip6),
283 ("%s: mbuf len %d < sizeof(ip6)", __func__, m->m_len));
286 * First create IP6 pseudo header and calculate a summary.
288 uph.ph.ph_len = htonl(len);
289 uph.ph.ph_zero[0] = uph.ph.ph_zero[1] = uph.ph.ph_zero[2] = 0;
292 /* Payload length and upper layer identifier. */
293 sum = uph.phs[0]; sum += uph.phs[1];
294 sum += uph.phs[2]; sum += uph.phs[3];
296 ip6 = mtod(m, struct ip6_hdr *);
298 /* IPv6 source address. */
299 scope = in6_getscope(&ip6->ip6_src);
300 w = (uint16_t *)&ip6->ip6_src;
301 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
302 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
306 /* IPv6 destination address. */
307 scope = in6_getscope(&ip6->ip6_dst);
308 w = (uint16_t *)&ip6->ip6_dst;
309 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
310 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
315 * Loop over the rest of the mbuf chain and compute the rest of the
316 * checksum. m_apply() handles unmapped mbufs.
320 (void)m_apply(m, off, cov, in6_cksum_partial_one, &arg);
324 * Handle a residual byte.
327 s_util.c[0] = arg.resid;
332 return (~sum & 0xffff);
336 in6_cksum(struct mbuf *m, uint8_t nxt, uint32_t off, uint32_t len)
338 return (in6_cksum_partial(m, nxt, off, len, len));