1 /* $FreeBSD$ */
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 * 4. 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 #include <net/net_osdep.h>
71
72 /*
73 * Checksum routine for Internet Protocol family headers (Portable Version).
74 *
75 * This routine is very heavily used in the network
76 * code and should be modified for each CPU to be as fast as possible.
77 */
78
79 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
80 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
81
82 /*
83 * m MUST contain a continuous IP6 header.
84 * off is an offset where TCP/UDP/ICMP6 header starts.
85 * len is a total length of a transport segment.
86 * (e.g. TCP header + TCP payload)
87 */
88
89 int
90 in6_cksum(m, nxt, off, len)
91 struct mbuf *m;
92 u_int8_t nxt;
93 u_int32_t off, len;
94 {
95 u_int16_t *w;
96 int sum = 0;
97 int mlen = 0;
98 int byte_swapped = 0;
99 struct ip6_hdr *ip6;
100 union {
101 u_int16_t phs[4];
102 struct {
103 u_int32_t ph_len;
104 u_int8_t ph_zero[3];
105 u_int8_t ph_nxt;
106 } ph __packed;
107 } uph;
108 union {
109 u_int8_t c[2];
110 u_int16_t s;
111 } s_util;
112 union {
113 u_int16_t s[2];
114 u_int32_t l;
115 } l_util;
116
117 /* sanity check */
118 if (m->m_pkthdr.len < off + len) {
119 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)",
120 m->m_pkthdr.len, off, len);
121 }
122
123 bzero(&uph, sizeof(uph));
124
125 /*
126 * First create IP6 pseudo header and calculate a summary.
127 */
128 ip6 = mtod(m, struct ip6_hdr *);
129 w = (u_int16_t *)&ip6->ip6_src;
130 uph.ph.ph_len = htonl(len);
131 uph.ph.ph_nxt = nxt;
132
133 /* IPv6 source address */
134 sum += w[0];
135 if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
136 sum += w[1];
137 sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
138 sum += w[6]; sum += w[7];
139 /* IPv6 destination address */
140 sum += w[8];
141 if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
142 sum += w[9];
143 sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13];
144 sum += w[14]; sum += w[15];
145 /* Payload length and upper layer identifier */
146 sum += uph.phs[0]; sum += uph.phs[1];
147 sum += uph.phs[2]; sum += uph.phs[3];
148
149 /*
150 * Secondly calculate a summary of the first mbuf excluding offset.
151 */
152 while (m != NULL && off > 0) {
153 if (m->m_len <= off)
154 off -= m->m_len;
155 else
156 break;
157 m = m->m_next;
158 }
159 w = (u_int16_t *)(mtod(m, u_char *) + off);
160 mlen = m->m_len - off;
161 if (len < mlen)
162 mlen = len;
163 len -= mlen;
164 /*
165 * Force to even boundary.
166 */
167 if ((1 & (long) w) && (mlen > 0)) {
168 REDUCE;
169 sum <<= 8;
170 s_util.c[0] = *(u_char *)w;
171 w = (u_int16_t *)((char *)w + 1);
172 mlen--;
173 byte_swapped = 1;
174 }
175 /*
176 * Unroll the loop to make overhead from
177 * branches &c small.
178 */
179 while ((mlen -= 32) >= 0) {
180 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
181 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
182 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
183 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
184 w += 16;
185 }
186 mlen += 32;
187 while ((mlen -= 8) >= 0) {
188 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
189 w += 4;
190 }
191 mlen += 8;
192 if (mlen == 0 && byte_swapped == 0)
193 goto next;
194 REDUCE;
195 while ((mlen -= 2) >= 0) {
196 sum += *w++;
197 }
198 if (byte_swapped) {
199 REDUCE;
200 sum <<= 8;
201 byte_swapped = 0;
202 if (mlen == -1) {
203 s_util.c[1] = *(char *)w;
204 sum += s_util.s;
205 mlen = 0;
206 } else
207 mlen = -1;
208 } else if (mlen == -1)
209 s_util.c[0] = *(char *)w;
210 next:
211 m = m->m_next;
212
213 /*
214 * Lastly calculate a summary of the rest of mbufs.
215 */
216
217 for (;m && len; m = m->m_next) {
218 if (m->m_len == 0)
219 continue;
220 w = mtod(m, u_int16_t *);
221 if (mlen == -1) {
222 /*
223 * The first byte of this mbuf is the continuation
224 * of a word spanning between this mbuf and the
225 * last mbuf.
226 *
227 * s_util.c[0] is already saved when scanning previous
228 * mbuf.
229 */
230 s_util.c[1] = *(char *)w;
231 sum += s_util.s;
232 w = (u_int16_t *)((char *)w + 1);
233 mlen = m->m_len - 1;
234 len--;
235 } else
236 mlen = m->m_len;
237 if (len < mlen)
238 mlen = len;
239 len -= mlen;
240 /*
241 * Force to even boundary.
242 */
243 if ((1 & (long) w) && (mlen > 0)) {
244 REDUCE;
245 sum <<= 8;
246 s_util.c[0] = *(u_char *)w;
247 w = (u_int16_t *)((char *)w + 1);
248 mlen--;
249 byte_swapped = 1;
250 }
251 /*
252 * Unroll the loop to make overhead from
253 * branches &c small.
254 */
255 while ((mlen -= 32) >= 0) {
256 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
257 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
258 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
259 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
260 w += 16;
261 }
262 mlen += 32;
263 while ((mlen -= 8) >= 0) {
264 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
265 w += 4;
266 }
267 mlen += 8;
268 if (mlen == 0 && byte_swapped == 0)
269 continue;
270 REDUCE;
271 while ((mlen -= 2) >= 0) {
272 sum += *w++;
273 }
274 if (byte_swapped) {
275 REDUCE;
276 sum <<= 8;
277 byte_swapped = 0;
278 if (mlen == -1) {
279 s_util.c[1] = *(char *)w;
280 sum += s_util.s;
281 mlen = 0;
282 } else
283 mlen = -1;
284 } else if (mlen == -1)
285 s_util.c[0] = *(char *)w;
286 }
287 if (len)
288 panic("in6_cksum: out of data");
289 if (mlen == -1) {
290 /* The last mbuf has odd # of bytes. Follow the
291 standard (the odd byte may be shifted left by 8 bits
292 or not as determined by endian-ness of the machine) */
293 s_util.c[1] = 0;
294 sum += s_util.s;
295 }
296 REDUCE;
297 return (~sum & 0xffff);
298 }
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