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 #include <netinet6/scope6_var.h>
70
71 /*
72 * Checksum routine for Internet Protocol family headers (Portable Version).
73 *
74 * This routine is very heavily used in the network
75 * code and should be modified for each CPU to be as fast as possible.
76 */
77
78 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
79 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
80
81 /*
82 * m MUST contain a continuous IP6 header.
83 * off is an offset where TCP/UDP/ICMP6 header starts.
84 * len is a total length of a transport segment.
85 * (e.g. TCP header + TCP payload)
86 */
87 int
88 in6_cksum(struct mbuf *m, u_int8_t nxt, u_int32_t off, u_int32_t len)
89 {
90 u_int16_t *w;
91 int sum = 0;
92 int mlen = 0;
93 int byte_swapped = 0;
94 struct ip6_hdr *ip6;
95 struct in6_addr in6;
96 union {
97 u_int16_t phs[4];
98 struct {
99 u_int32_t ph_len;
100 u_int8_t ph_zero[3];
101 u_int8_t ph_nxt;
102 } __packed ph;
103 } uph;
104 union {
105 u_int8_t c[2];
106 u_int16_t s;
107 } s_util;
108 union {
109 u_int16_t s[2];
110 u_int32_t l;
111 } l_util;
112
113 /* sanity check */
114 if (m->m_pkthdr.len < off + len) {
115 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)",
116 m->m_pkthdr.len, off, len);
117 }
118
119 bzero(&uph, sizeof(uph));
120
121 /*
122 * First create IP6 pseudo header and calculate a summary.
123 */
124 ip6 = mtod(m, struct ip6_hdr *);
125 uph.ph.ph_len = htonl(len);
126 uph.ph.ph_nxt = nxt;
127
128 /*
129 * IPv6 source address.
130 * XXX: we'd like to avoid copying the address, but we can't due to
131 * the possibly embedded scope zone ID.
132 */
133 in6 = ip6->ip6_src;
134 in6_clearscope(&in6);
135 w = (u_int16_t *)&in6;
136 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
137 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
138
139 /* IPv6 destination address */
140 in6 = ip6->ip6_dst;
141 in6_clearscope(&in6);
142 w = (u_int16_t *)&in6;
143 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
144 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
145
146 /* Payload length and upper layer identifier */
147 sum += uph.phs[0]; sum += uph.phs[1];
148 sum += uph.phs[2]; sum += uph.phs[3];
149
150 /*
151 * Secondly calculate a summary of the first mbuf excluding offset.
152 */
153 while (off > 0) {
154 if (m->m_len <= off)
155 off -= m->m_len;
156 else
157 break;
158 m = m->m_next;
159 }
160 w = (u_int16_t *)(mtod(m, u_char *) + off);
161 mlen = m->m_len - off;
162 if (len < mlen)
163 mlen = len;
164 len -= mlen;
165 /*
166 * Force to even boundary.
167 */
168 if ((1 & (long) w) && (mlen > 0)) {
169 REDUCE;
170 sum <<= 8;
171 s_util.c[0] = *(u_char *)w;
172 w = (u_int16_t *)((char *)w + 1);
173 mlen--;
174 byte_swapped = 1;
175 }
176 /*
177 * Unroll the loop to make overhead from
178 * branches &c small.
179 */
180 while ((mlen -= 32) >= 0) {
181 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
182 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
183 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
184 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
185 w += 16;
186 }
187 mlen += 32;
188 while ((mlen -= 8) >= 0) {
189 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
190 w += 4;
191 }
192 mlen += 8;
193 if (mlen == 0 && byte_swapped == 0)
194 goto next;
195 REDUCE;
196 while ((mlen -= 2) >= 0) {
197 sum += *w++;
198 }
199 if (byte_swapped) {
200 REDUCE;
201 sum <<= 8;
202 byte_swapped = 0;
203 if (mlen == -1) {
204 s_util.c[1] = *(char *)w;
205 sum += s_util.s;
206 mlen = 0;
207 } else
208 mlen = -1;
209 } else if (mlen == -1)
210 s_util.c[0] = *(char *)w;
211 next:
212 m = m->m_next;
213
214 /*
215 * Lastly calculate a summary of the rest of mbufs.
216 */
217
218 for (;m && len; m = m->m_next) {
219 if (m->m_len == 0)
220 continue;
221 w = mtod(m, u_int16_t *);
222 if (mlen == -1) {
223 /*
224 * The first byte of this mbuf is the continuation
225 * of a word spanning between this mbuf and the
226 * last mbuf.
227 *
228 * s_util.c[0] is already saved when scanning previous
229 * mbuf.
230 */
231 s_util.c[1] = *(char *)w;
232 sum += s_util.s;
233 w = (u_int16_t *)((char *)w + 1);
234 mlen = m->m_len - 1;
235 len--;
236 } else
237 mlen = m->m_len;
238 if (len < mlen)
239 mlen = len;
240 len -= mlen;
241 /*
242 * Force to even boundary.
243 */
244 if ((1 & (long) w) && (mlen > 0)) {
245 REDUCE;
246 sum <<= 8;
247 s_util.c[0] = *(u_char *)w;
248 w = (u_int16_t *)((char *)w + 1);
249 mlen--;
250 byte_swapped = 1;
251 }
252 /*
253 * Unroll the loop to make overhead from
254 * branches &c small.
255 */
256 while ((mlen -= 32) >= 0) {
257 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
258 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
259 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
260 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
261 w += 16;
262 }
263 mlen += 32;
264 while ((mlen -= 8) >= 0) {
265 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
266 w += 4;
267 }
268 mlen += 8;
269 if (mlen == 0 && byte_swapped == 0)
270 continue;
271 REDUCE;
272 while ((mlen -= 2) >= 0) {
273 sum += *w++;
274 }
275 if (byte_swapped) {
276 REDUCE;
277 sum <<= 8;
278 byte_swapped = 0;
279 if (mlen == -1) {
280 s_util.c[1] = *(char *)w;
281 sum += s_util.s;
282 mlen = 0;
283 } else
284 mlen = -1;
285 } else if (mlen == -1)
286 s_util.c[0] = *(char *)w;
287 }
288 if (len)
289 panic("in6_cksum: out of data");
290 if (mlen == -1) {
291 /* The last mbuf has odd # of bytes. Follow the
292 standard (the odd byte may be shifted left by 8 bits
293 or not as determined by endian-ness of the machine) */
294 s_util.c[1] = 0;
295 sum += s_util.s;
296 }
297 REDUCE;
298 return (~sum & 0xffff);
299 }
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