1 /* $OpenBSD: in6_cksum.c,v 1.14 2006/11/17 01:11:23 itojun Exp $ */
2 /* $KAME: in6_cksum.c,v 1.10 2000/12/03 00:53:59 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/param.h>
65 #include <sys/mbuf.h>
66 #include <sys/systm.h>
67 #include <netinet/in.h>
68 #include <netinet/ip6.h>
69
70 /*
71 * Checksum routine for Internet Protocol family headers (Portable Version).
72 *
73 * This routine is very heavily used in the network
74 * code and should be modified for each CPU to be as fast as possible.
75 */
76
77 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
78 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
79
80 /*
81 * m MUST contain a continuous IP6 header.
82 * off is a offset where TCP/UDP/ICMP6 header starts.
83 * len is a total length of a transport segment.
84 * (e.g. TCP header + TCP payload)
85 */
86
87 int
88 in6_cksum(m, nxt, off, len)
89 struct mbuf *m;
90 u_int8_t nxt;
91 u_int32_t off, len;
92 {
93 u_int16_t *w;
94 int sum = 0;
95 int mlen = 0;
96 int byte_swapped = 0;
97 struct ip6_hdr *ip6;
98 union {
99 u_int16_t phs[4];
100 struct {
101 u_int32_t ph_len;
102 u_int8_t ph_zero[3];
103 u_int8_t ph_nxt;
104 } ph __packed;
105 } uph;
106 union {
107 u_int8_t c[2];
108 u_int16_t s;
109 } s_util;
110 union {
111 u_int16_t s[2];
112 u_int32_t l;
113 } l_util;
114
115 /* sanity check */
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);
119 }
120
121 bzero(&uph, sizeof(uph));
122
123 /*
124 * First create IP6 pseudo header and calculate a summary.
125 */
126 ip6 = mtod(m, struct ip6_hdr *);
127 w = (u_int16_t *)&ip6->ip6_src;
128 uph.ph.ph_len = htonl(len);
129 uph.ph.ph_nxt = nxt;
130
131 /* IPv6 source address */
132 sum += w[0];
133 if (!IN6_IS_SCOPE_EMBED(&ip6->ip6_src))
134 sum += w[1];
135 sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
136 sum += w[6]; sum += w[7];
137 /* IPv6 destination address */
138 sum += w[8];
139 if (!IN6_IS_SCOPE_EMBED(&ip6->ip6_dst))
140 sum += w[9];
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];
146
147 /*
148 * Secondly calculate a summary of the first mbuf excluding offset.
149 */
150 while (m != NULL && off > 0) {
151 if (m->m_len <= off)
152 off -= m->m_len;
153 else
154 break;
155 m = m->m_next;
156 }
157 w = (u_int16_t *)(mtod(m, u_char *) + off);
158 mlen = m->m_len - off;
159 if (len < mlen)
160 mlen = len;
161 len -= mlen;
162 /*
163 * Force to even boundary.
164 */
165 if ((1 & (long) w) && (mlen > 0)) {
166 REDUCE;
167 sum <<= 8;
168 s_util.c[0] = *(u_char *)w;
169 w = (u_int16_t *)((char *)w + 1);
170 mlen--;
171 byte_swapped = 1;
172 }
173 /*
174 * Unroll the loop to make overhead from
175 * branches &c small.
176 */
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];
182 w += 16;
183 }
184 mlen += 32;
185 while ((mlen -= 8) >= 0) {
186 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
187 w += 4;
188 }
189 mlen += 8;
190 if (mlen == 0 && byte_swapped == 0)
191 goto next;
192 REDUCE;
193 while ((mlen -= 2) >= 0) {
194 sum += *w++;
195 }
196 if (byte_swapped) {
197 REDUCE;
198 sum <<= 8;
199 byte_swapped = 0;
200 if (mlen == -1) {
201 s_util.c[1] = *(char *)w;
202 sum += s_util.s;
203 mlen = 0;
204 } else
205 mlen = -1;
206 } else if (mlen == -1)
207 s_util.c[0] = *(char *)w;
208 next:
209 m = m->m_next;
210
211 /*
212 * Lastly calculate a summary of the rest of mbufs.
213 */
214
215 for (;m && len; m = m->m_next) {
216 if (m->m_len == 0)
217 continue;
218 w = mtod(m, u_int16_t *);
219 if (mlen == -1) {
220 /*
221 * The first byte of this mbuf is the continuation
222 * of a word spanning between this mbuf and the
223 * last mbuf.
224 *
225 * s_util.c[0] is already saved when scanning previous
226 * mbuf.
227 */
228 s_util.c[1] = *(char *)w;
229 sum += s_util.s;
230 w = (u_int16_t *)((char *)w + 1);
231 mlen = m->m_len - 1;
232 len--;
233 } else
234 mlen = m->m_len;
235 if (len < mlen)
236 mlen = len;
237 len -= mlen;
238 /*
239 * Force to even boundary.
240 */
241 if ((1 & (long) w) && (mlen > 0)) {
242 REDUCE;
243 sum <<= 8;
244 s_util.c[0] = *(u_char *)w;
245 w = (u_int16_t *)((char *)w + 1);
246 mlen--;
247 byte_swapped = 1;
248 }
249 /*
250 * Unroll the loop to make overhead from
251 * branches &c small.
252 */
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];
258 w += 16;
259 }
260 mlen += 32;
261 while ((mlen -= 8) >= 0) {
262 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
263 w += 4;
264 }
265 mlen += 8;
266 if (mlen == 0 && byte_swapped == 0)
267 continue;
268 REDUCE;
269 while ((mlen -= 2) >= 0) {
270 sum += *w++;
271 }
272 if (byte_swapped) {
273 REDUCE;
274 sum <<= 8;
275 byte_swapped = 0;
276 if (mlen == -1) {
277 s_util.c[1] = *(char *)w;
278 sum += s_util.s;
279 mlen = 0;
280 } else
281 mlen = -1;
282 } else if (mlen == -1)
283 s_util.c[0] = *(char *)w;
284 }
285 if (len)
286 panic("in6_cksum: out of data");
287 if (mlen == -1) {
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) */
291 s_util.c[1] = 0;
292 sum += s_util.s;
293 }
294 REDUCE;
295 return (~sum & 0xffff);
296 }