xref: /freebsd/sys/netinet6/in6_cksum.c (revision 41466b50c1d5bfd1cf6adaae547a579a75d7c04e)
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  * 3. All advertising materials mentioning features or use of this software
46  *    must display the following acknowledgement:
47  *	This product includes software developed by the University of
48  *	California, Berkeley and its contributors.
49  * 4. Neither the name of the University nor the names of its contributors
50  *    may be used to endorse or promote products derived from this software
51  *    without specific prior written permission.
52  *
53  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
54  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
55  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
56  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
57  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
58  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
59  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
60  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
61  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
62  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
63  * SUCH DAMAGE.
64  *
65  *	@(#)in_cksum.c	8.1 (Berkeley) 6/10/93
66  */
67 
68 #include <sys/param.h>
69 #include <sys/mbuf.h>
70 #include <sys/systm.h>
71 #include <netinet/in.h>
72 #include <netinet/ip6.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 #if 0
104 	int srcifid = 0, dstifid = 0;
105 #endif
106 	struct ip6_hdr *ip6;
107 	union {
108 		u_int16_t phs[4];
109 		struct {
110 			u_int32_t	ph_len;
111 			u_int8_t	ph_zero[3];
112 			u_int8_t	ph_nxt;
113 		} ph __attribute__((__packed__));
114 	} uph;
115 	union {
116 		u_int8_t	c[2];
117 		u_int16_t	s;
118 	} s_util;
119 	union {
120 		u_int16_t s[2];
121 		u_int32_t l;
122 	} l_util;
123 
124 	/* sanity check */
125 	if (m->m_pkthdr.len < off + len) {
126 		panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)\n",
127 			m->m_pkthdr.len, off, len);
128 	}
129 
130 	bzero(&uph, sizeof(uph));
131 
132 	/*
133 	 * First create IP6 pseudo header and calculate a summary.
134 	 */
135 	ip6 = mtod(m, struct ip6_hdr *);
136 #if 0
137 	if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) {
138 		srcifid = ip6->ip6_src.s6_addr16[1];
139 		ip6->ip6_src.s6_addr16[1] = 0;
140 	}
141 	if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) {
142 		dstifid = ip6->ip6_dst.s6_addr16[1];
143 		ip6->ip6_dst.s6_addr16[1] = 0;
144 	}
145 #endif
146 	w = (u_int16_t *)&ip6->ip6_src;
147 	uph.ph.ph_len = htonl(len);
148 	uph.ph.ph_nxt = nxt;
149 
150 	/* IPv6 source address */
151 	sum += w[0];
152 	if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
153 		sum += w[1];
154 	sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
155 	sum += w[6]; sum += w[7];
156 	/* IPv6 destination address */
157 	sum += w[8];
158 	if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
159 		sum += w[9];
160 	sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13];
161 	sum += w[14]; sum += w[15];
162 	/* Payload length and upper layer identifier */
163 	sum += uph.phs[0];  sum += uph.phs[1];
164 	sum += uph.phs[2];  sum += uph.phs[3];
165 
166 #if 0
167 	if (srcifid)
168 		ip6->ip6_src.s6_addr16[1] = srcifid;
169 	if (dstifid)
170 		ip6->ip6_dst.s6_addr16[1] = dstifid;
171 #endif
172 	/*
173 	 * Secondly calculate a summary of the first mbuf excluding offset.
174 	 */
175 	while (m != NULL && off > 0) {
176 		if (m->m_len <= off)
177 			off -= m->m_len;
178 		else
179 			break;
180 		m = m->m_next;
181 	}
182 	w = (u_int16_t *)(mtod(m, u_char *) + off);
183 	mlen = m->m_len - off;
184 	if (len < mlen)
185 		mlen = len;
186 	len -= mlen;
187 	/*
188 	 * Force to even boundary.
189 	 */
190 	if ((1 & (long) w) && (mlen > 0)) {
191 		REDUCE;
192 		sum <<= 8;
193 		s_util.c[0] = *(u_char *)w;
194 		w = (u_int16_t *)((char *)w + 1);
195 		mlen--;
196 		byte_swapped = 1;
197 	}
198 	/*
199 	 * Unroll the loop to make overhead from
200 	 * branches &c small.
201 	 */
202 	while ((mlen -= 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];
207 		w += 16;
208 	}
209 	mlen += 32;
210 	while ((mlen -= 8) >= 0) {
211 		sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
212 		w += 4;
213 	}
214 	mlen += 8;
215 	if (mlen == 0 && byte_swapped == 0)
216 		goto next;
217 	REDUCE;
218 	while ((mlen -= 2) >= 0) {
219 		sum += *w++;
220 	}
221 	if (byte_swapped) {
222 		REDUCE;
223 		sum <<= 8;
224 		byte_swapped = 0;
225 		if (mlen == -1) {
226 			s_util.c[1] = *(char *)w;
227 			sum += s_util.s;
228 			mlen = 0;
229 		} else
230 			mlen = -1;
231 	} else if (mlen == -1)
232 		s_util.c[0] = *(char *)w;
233  next:
234 	m = m->m_next;
235 
236 	/*
237 	 * Lastly calculate a summary of the rest of mbufs.
238 	 */
239 
240 	for (;m && len; m = m->m_next) {
241 		if (m->m_len == 0)
242 			continue;
243 		w = mtod(m, u_int16_t *);
244 		if (mlen == -1) {
245 			/*
246 			 * The first byte of this mbuf is the continuation
247 			 * of a word spanning between this mbuf and the
248 			 * last mbuf.
249 			 *
250 			 * s_util.c[0] is already saved when scanning previous
251 			 * mbuf.
252 			 */
253 			s_util.c[1] = *(char *)w;
254 			sum += s_util.s;
255 			w = (u_int16_t *)((char *)w + 1);
256 			mlen = m->m_len - 1;
257 			len--;
258 		} else
259 			mlen = m->m_len;
260 		if (len < mlen)
261 			mlen = len;
262 		len -= mlen;
263 		/*
264 		 * Force to even boundary.
265 		 */
266 		if ((1 & (long) w) && (mlen > 0)) {
267 			REDUCE;
268 			sum <<= 8;
269 			s_util.c[0] = *(u_char *)w;
270 			w = (u_int16_t *)((char *)w + 1);
271 			mlen--;
272 			byte_swapped = 1;
273 		}
274 		/*
275 		 * Unroll the loop to make overhead from
276 		 * branches &c small.
277 		 */
278 		while ((mlen -= 32) >= 0) {
279 			sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
280 			sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
281 			sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
282 			sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
283 			w += 16;
284 		}
285 		mlen += 32;
286 		while ((mlen -= 8) >= 0) {
287 			sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
288 			w += 4;
289 		}
290 		mlen += 8;
291 		if (mlen == 0 && byte_swapped == 0)
292 			continue;
293 		REDUCE;
294 		while ((mlen -= 2) >= 0) {
295 			sum += *w++;
296 		}
297 		if (byte_swapped) {
298 			REDUCE;
299 			sum <<= 8;
300 			byte_swapped = 0;
301 			if (mlen == -1) {
302 				s_util.c[1] = *(char *)w;
303 				sum += s_util.s;
304 				mlen = 0;
305 			} else
306 				mlen = -1;
307 		} else if (mlen == -1)
308 			s_util.c[0] = *(char *)w;
309 	}
310 	if (len)
311 		panic("in6_cksum: out of data\n");
312 	if (mlen == -1) {
313 		/* The last mbuf has odd # of bytes. Follow the
314 		   standard (the odd byte may be shifted left by 8 bits
315 		   or not as determined by endian-ness of the machine) */
316 		s_util.c[1] = 0;
317 		sum += s_util.s;
318 	}
319 	REDUCE;
320 	return (~sum & 0xffff);
321 }
322