1 /* $NetBSD: in6_cksum.c,v 1.19 2006/01/27 20:08:11 rpaulo Exp $ */
2 /* $KAME: in6_cksum.c,v 1.9 2000/09/09 15:33:31 itojun Exp $ */
3
4 /*
5 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the project nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 /*
34 * Copyright (c) 1988, 1992, 1993
35 * The Regents of the University of California. All rights reserved.
36 *
37 * Redistribution and use in source and binary forms, with or without
38 * modification, are permitted provided that the following conditions
39 * are met:
40 * 1. Redistributions of source code must retain the above copyright
41 * notice, this list of conditions and the following disclaimer.
42 * 2. Redistributions in binary form must reproduce the above copyright
43 * notice, this list of conditions and the following disclaimer in the
44 * documentation and/or other materials provided with the distribution.
45 * 3. Neither the name of the University nor the names of its contributors
46 * may be used to endorse or promote products derived from this software
47 * without specific prior written permission.
48 *
49 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
50 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
51 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
52 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
53 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
54 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
55 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
56 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
57 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
58 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
59 * SUCH DAMAGE.
60 *
61 * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
62 */
63
64 #include <sys/cdefs.h>
65 __KERNEL_RCSID(0, "$NetBSD: in6_cksum.c,v 1.19 2006/01/27 20:08:11 rpaulo Exp $");
66
67 #include <sys/param.h>
68 #include <sys/mbuf.h>
69 #include <sys/systm.h>
70 #include <netinet/in.h>
71 #include <netinet/ip6.h>
72 #include <netinet6/scope6_var.h>
73
74 #include <net/net_osdep.h>
75
76 /*
77 * Checksum routine for Internet Protocol family headers (Portable Version).
78 *
79 * This routine is very heavily used in the network
80 * code and should be modified for each CPU to be as fast as possible.
81 */
82
83 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
84 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
85
86 /*
87 * m MUST contain a continuous IP6 header.
88 * off is a offset where TCP/UDP/ICMP6 header starts.
89 * len is a total length of a transport segment.
90 * (e.g. TCP header + TCP payload)
91 */
92
93 int
94 in6_cksum(m, nxt, off, len)
95 struct mbuf *m;
96 u_int8_t nxt;
97 u_int32_t off, len;
98 {
99 u_int16_t *w;
100 int sum = 0;
101 int mlen = 0;
102 int byte_swapped = 0;
103 struct ip6_hdr *ip6;
104 struct in6_addr in6;
105 union {
106 u_int16_t phs[4];
107 struct {
108 u_int32_t ph_len;
109 u_int8_t ph_zero[3];
110 u_int8_t ph_nxt;
111 } ph __attribute__((__packed__));
112 } uph;
113 union {
114 u_int8_t c[2];
115 u_int16_t s;
116 } s_util;
117 union {
118 u_int16_t s[2];
119 u_int32_t l;
120 } l_util;
121
122 /* sanity check */
123 if (m->m_pkthdr.len < off + len) {
124 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)",
125 m->m_pkthdr.len, off, len);
126 }
127
128 /* Skip pseudo-header if nxt == 0. */
129 if (nxt == 0)
130 goto skip_phdr;
131
132 bzero(&uph, sizeof(uph));
133
134 /*
135 * First create IP6 pseudo header and calculate a summary.
136 */
137 ip6 = mtod(m, struct ip6_hdr *);
138 w = (u_int16_t *)&ip6->ip6_src;
139 uph.ph.ph_len = htonl(len);
140 uph.ph.ph_nxt = nxt;
141
142 /*
143 * IPv6 source address
144 * XXX: we'd like to avoid copying the address, but we can't due to
145 * the possibly embedded scope zone ID.
146 */
147 in6 = ip6->ip6_src;
148 in6_clearscope(&in6);
149 w = (u_int16_t *)&in6;
150 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
151 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
152
153 /* IPv6 destination address */
154 in6 = ip6->ip6_dst;
155 in6_clearscope(&in6);
156 w = (u_int16_t *)&in6;
157 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
158 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
159
160 /* Payload length and upper layer identifier */
161 sum += uph.phs[0]; sum += uph.phs[1];
162 sum += uph.phs[2]; sum += uph.phs[3];
163
164 skip_phdr:
165 /*
166 * Secondly calculate a summary of the first mbuf excluding offset.
167 */
168 while (m != NULL && off > 0) {
169 if (m->m_len <= off)
170 off -= m->m_len;
171 else
172 break;
173 m = m->m_next;
174 }
175 w = (u_int16_t *)(mtod(m, u_char *) + off);
176 mlen = m->m_len - off;
177 if (len < mlen)
178 mlen = len;
179 len -= mlen;
180 /*
181 * Force to even boundary.
182 */
183 if ((1 & (long) w) && (mlen > 0)) {
184 REDUCE;
185 sum <<= 8;
186 s_util.c[0] = *(u_char *)w;
187 w = (u_int16_t *)((char *)w + 1);
188 mlen--;
189 byte_swapped = 1;
190 }
191 /*
192 * Unroll the loop to make overhead from
193 * branches &c small.
194 */
195 while ((mlen -= 32) >= 0) {
196 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
197 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
198 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
199 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
200 w += 16;
201 }
202 mlen += 32;
203 while ((mlen -= 8) >= 0) {
204 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
205 w += 4;
206 }
207 mlen += 8;
208 if (mlen == 0 && byte_swapped == 0)
209 goto next;
210 REDUCE;
211 while ((mlen -= 2) >= 0) {
212 sum += *w++;
213 }
214 if (byte_swapped) {
215 REDUCE;
216 sum <<= 8;
217 byte_swapped = 0;
218 if (mlen == -1) {
219 s_util.c[1] = *(char *)w;
220 sum += s_util.s;
221 mlen = 0;
222 } else
223 mlen = -1;
224 } else if (mlen == -1)
225 s_util.c[0] = *(char *)w;
226 next:
227 m = m->m_next;
228
229 /*
230 * Lastly calculate a summary of the rest of mbufs.
231 */
232
233 for (;m && len; m = m->m_next) {
234 if (m->m_len == 0)
235 continue;
236 w = mtod(m, u_int16_t *);
237 if (mlen == -1) {
238 /*
239 * The first byte of this mbuf is the continuation
240 * of a word spanning between this mbuf and the
241 * last mbuf.
242 *
243 * s_util.c[0] is already saved when scanning previous
244 * mbuf.
245 */
246 s_util.c[1] = *(char *)w;
247 sum += s_util.s;
248 w = (u_int16_t *)((char *)w + 1);
249 mlen = m->m_len - 1;
250 len--;
251 } else
252 mlen = m->m_len;
253 if (len < mlen)
254 mlen = len;
255 len -= mlen;
256 /*
257 * Force to even boundary.
258 */
259 if ((1 & (long) w) && (mlen > 0)) {
260 REDUCE;
261 sum <<= 8;
262 s_util.c[0] = *(u_char *)w;
263 w = (u_int16_t *)((char *)w + 1);
264 mlen--;
265 byte_swapped = 1;
266 }
267 /*
268 * Unroll the loop to make overhead from
269 * branches &c small.
270 */
271 while ((mlen -= 32) >= 0) {
272 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
273 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
274 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
275 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
276 w += 16;
277 }
278 mlen += 32;
279 while ((mlen -= 8) >= 0) {
280 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
281 w += 4;
282 }
283 mlen += 8;
284 if (mlen == 0 && byte_swapped == 0)
285 continue;
286 REDUCE;
287 while ((mlen -= 2) >= 0) {
288 sum += *w++;
289 }
290 if (byte_swapped) {
291 REDUCE;
292 sum <<= 8;
293 byte_swapped = 0;
294 if (mlen == -1) {
295 s_util.c[1] = *(char *)w;
296 sum += s_util.s;
297 mlen = 0;
298 } else
299 mlen = -1;
300 } else if (mlen == -1)
301 s_util.c[0] = *(char *)w;
302 }
303 if (len)
304 panic("in6_cksum: out of data");
305 if (mlen == -1) {
306 /* The last mbuf has odd # of bytes. Follow the
307 standard (the odd byte may be shifted left by 8 bits
308 or not as determined by endian-ness of the machine) */
309 s_util.c[1] = 0;
310 sum += s_util.s;
311 }
312 REDUCE;
313 return (~sum & 0xffff);
314 }
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