1 /* $OpenBSD: in4_cksum.c,v 1.7 2003/06/02 23:28:13 millert Exp $ */
2 /* $KAME: in4_cksum.c,v 1.10 2001/11/30 10:06:15 itojun Exp $ */
3 /* $NetBSD: in_cksum.c,v 1.13 1996/10/13 02:03:03 christos Exp $ */
4
5 /*
6 * Copyright (C) 1999 WIDE Project.
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the project nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34 /*
35 * Copyright (c) 1988, 1992, 1993
36 * The Regents of the University of California. All rights reserved.
37 *
38 * Redistribution and use in source and binary forms, with or without
39 * modification, are permitted provided that the following conditions
40 * are met:
41 * 1. Redistributions of source code must retain the above copyright
42 * notice, this list of conditions and the following disclaimer.
43 * 2. Redistributions in binary form must reproduce the above copyright
44 * notice, this list of conditions and the following disclaimer in the
45 * documentation and/or other materials provided with the distribution.
46 * 3. Neither the name of the University nor the names of its contributors
47 * may be used to endorse or promote products derived from this software
48 * without specific prior written permission.
49 *
50 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
51 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
52 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
53 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
54 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
55 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
56 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
57 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
58 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
59 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
60 * SUCH DAMAGE.
61 *
62 * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
63 */
64
65 #include <sys/param.h>
66 #include <sys/mbuf.h>
67 #include <sys/systm.h>
68 #include <sys/socket.h>
69 #include <net/route.h>
70 #include <netinet/in.h>
71 #include <netinet/in_systm.h>
72 #include <netinet/ip.h>
73 #include <netinet/ip_var.h>
74
75 /*
76 * Checksum routine for Internet Protocol family headers (Portable Version).
77 * This is only for IPv4 pseudo header checksum.
78 * No need to clear non-pseudo-header fields in IPv4 header.
79 * len is for actual payload size, and does not include IPv4 header and
80 * skipped header chain (off + len should be equal to the whole packet).
81 *
82 * This routine is very heavily used in the network
83 * code and should be modified for each CPU to be as fast as possible.
84 */
85
86 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
87 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
88
89 int
90 in4_cksum(m, nxt, off, len)
91 struct mbuf *m;
92 u_int8_t nxt;
93 int off, len;
94 {
95 u_int16_t *w;
96 int sum = 0;
97 int mlen = 0;
98 int byte_swapped = 0;
99 union {
100 struct ipovly ipov;
101 u_int16_t w[10];
102 } u;
103 union {
104 u_int8_t c[2];
105 u_int16_t s;
106 } s_util;
107 union {
108 u_int16_t s[2];
109 u_int32_t l;
110 } l_util;
111
112 if (nxt != 0) {
113 /* pseudo header */
114 if (off < sizeof(struct ipovly))
115 panic("in4_cksum: offset too short");
116 if (m->m_len < sizeof(struct ip))
117 panic("in4_cksum: bad mbuf chain");
118 bzero(&u.ipov, sizeof(u.ipov));
119 u.ipov.ih_len = htons(len);
120 u.ipov.ih_pr = nxt;
121 u.ipov.ih_src = mtod(m, struct ip *)->ip_src;
122 u.ipov.ih_dst = mtod(m, struct ip *)->ip_dst;
123 w = u.w;
124 /* assumes sizeof(ipov) == 20 */
125 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; sum += w[4];
126 sum += w[5]; sum += w[6]; sum += w[7]; sum += w[8]; sum += w[9];
127 }
128
129 /* skip unnecessary part */
130 while (m && off > 0) {
131 if (m->m_len > off)
132 break;
133 off -= m->m_len;
134 m = m->m_next;
135 }
136
137 for (;m && len; m = m->m_next) {
138 if (m->m_len == 0)
139 continue;
140 w = (u_int16_t *)(mtod(m, caddr_t) + off);
141 if (mlen == -1) {
142 /*
143 * The first byte of this mbuf is the continuation
144 * of a word spanning between this mbuf and the
145 * last mbuf.
146 *
147 * s_util.c[0] is already saved when scanning previous
148 * mbuf.
149 */
150 s_util.c[1] = *(u_int8_t *)w;
151 sum += s_util.s;
152 w = (u_int16_t *)((u_int8_t *)w + 1);
153 mlen = m->m_len - off - 1;
154 len--;
155 } else
156 mlen = m->m_len - off;
157 off = 0;
158 if (len < mlen)
159 mlen = len;
160 len -= mlen;
161 /*
162 * Force to even boundary.
163 */
164 if ((1 & (long) w) && (mlen > 0)) {
165 REDUCE;
166 sum <<= 8;
167 s_util.c[0] = *(u_int8_t *)w;
168 w = (u_int16_t *)((int8_t *)w + 1);
169 mlen--;
170 byte_swapped = 1;
171 }
172 /*
173 * Unroll the loop to make overhead from
174 * branches &c small.
175 */
176 while ((mlen -= 32) >= 0) {
177 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
178 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
179 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
180 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
181 w += 16;
182 }
183 mlen += 32;
184 while ((mlen -= 8) >= 0) {
185 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
186 w += 4;
187 }
188 mlen += 8;
189 if (mlen == 0 && byte_swapped == 0)
190 continue;
191 REDUCE;
192 while ((mlen -= 2) >= 0) {
193 sum += *w++;
194 }
195 if (byte_swapped) {
196 REDUCE;
197 sum <<= 8;
198 byte_swapped = 0;
199 if (mlen == -1) {
200 s_util.c[1] = *(u_int8_t *)w;
201 sum += s_util.s;
202 mlen = 0;
203 } else
204 mlen = -1;
205 } else if (mlen == -1)
206 s_util.c[0] = *(u_int8_t *)w;
207 }
208 if (len)
209 printf("cksum4: out of data\n");
210 if (mlen == -1) {
211 /* The last mbuf has odd # of bytes. Follow the
212 standard (the odd byte may be shifted left by 8 bits
213 or not as determined by endian-ness of the machine) */
214 s_util.c[1] = 0;
215 sum += s_util.s;
216 }
217 REDUCE;
218 return (~sum & 0xffff);
219 }