1 /* $NetBSD: in4_cksum.c,v 1.10 2003/08/07 16:33:10 agc Exp $ */
2
3 /*
4 * Copyright (C) 1999 WIDE Project.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the project nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 /*
33 * Copyright (c) 1988, 1992, 1993
34 * The Regents of the University of California. All rights reserved.
35 *
36 * Redistribution and use in source and binary forms, with or without
37 * modification, are permitted provided that the following conditions
38 * are met:
39 * 1. Redistributions of source code must retain the above copyright
40 * notice, this list of conditions and the following disclaimer.
41 * 2. Redistributions in binary form must reproduce the above copyright
42 * notice, this list of conditions and the following disclaimer in the
43 * documentation and/or other materials provided with the distribution.
44 * 3. Neither the name of the University nor the names of its contributors
45 * may be used to endorse or promote products derived from this software
46 * without specific prior written permission.
47 *
48 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
49 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
50 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
51 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
52 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
53 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
54 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
55 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
56 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
57 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
58 * SUCH DAMAGE.
59 *
60 * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
61 */
62
63 #include <sys/cdefs.h>
64 __KERNEL_RCSID(0, "$NetBSD: in4_cksum.c,v 1.10 2003/08/07 16:33:10 agc Exp $");
65
66 #include <sys/param.h>
67 #include <sys/mbuf.h>
68 #include <sys/systm.h>
69 #include <sys/socket.h>
70 #include <net/route.h>
71 #include <netinet/in.h>
72 #include <netinet/in_systm.h>
73 #include <netinet/ip.h>
74 #include <netinet/ip_var.h>
75
76 /*
77 * Checksum routine for Internet Protocol family headers (Portable Version).
78 * This is only for IPv4 pseudo header checksum.
79 * No need to clear non-pseudo-header fields in IPv4 header.
80 * len is for actual payload size, and does not include IPv4 header and
81 * skipped header chain (off + len should be equal to the whole packet).
82 *
83 * This routine is very heavily used in the network
84 * code and should be modified for each CPU to be as fast as possible.
85 */
86
87 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
88 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
89
90 int
91 in4_cksum(m, nxt, off, len)
92 struct mbuf *m;
93 u_int8_t nxt;
94 int off, len;
95 {
96 u_int16_t *w;
97 int sum = 0;
98 int mlen = 0;
99 int byte_swapped = 0;
100 union {
101 struct ipovly ipov;
102 u_int16_t w[10];
103 } u;
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 if (nxt != 0) {
114 /* pseudo header */
115 if (off < sizeof(struct ipovly))
116 panic("in4_cksum: offset too short");
117 if (m->m_len < sizeof(struct ip))
118 panic("in4_cksum: bad mbuf chain");
119 bzero(&u.ipov, sizeof(u.ipov));
120 u.ipov.ih_len = htons(len);
121 u.ipov.ih_pr = nxt;
122 u.ipov.ih_src = mtod(m, struct ip *)->ip_src;
123 u.ipov.ih_dst = mtod(m, struct ip *)->ip_dst;
124 w = u.w;
125 /* assumes sizeof(ipov) == 20 */
126 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; sum += w[4];
127 sum += w[5]; sum += w[6]; sum += w[7]; sum += w[8]; sum += w[9];
128 }
129
130 /* skip unnecessary part */
131 while (m && off > 0) {
132 if (m->m_len > off)
133 break;
134 off -= m->m_len;
135 m = m->m_next;
136 }
137
138 for (;m && len; m = m->m_next) {
139 if (m->m_len == 0)
140 continue;
141 w = (u_int16_t *)(mtod(m, caddr_t) + off);
142 if (mlen == -1) {
143 /*
144 * The first byte of this mbuf is the continuation
145 * of a word spanning between this mbuf and the
146 * last mbuf.
147 *
148 * s_util.c[0] is already saved when scanning previous
149 * mbuf.
150 */
151 s_util.c[1] = *(u_int8_t *)w;
152 sum += s_util.s;
153 w = (u_int16_t *)((u_int8_t *)w + 1);
154 mlen = m->m_len - off - 1;
155 len--;
156 } else
157 mlen = m->m_len - off;
158 off = 0;
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_int8_t *)w;
169 w = (u_int16_t *)((int8_t *)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 continue;
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] = *(u_int8_t *)w;
202 sum += s_util.s;
203 mlen = 0;
204 } else
205 mlen = -1;
206 } else if (mlen == -1)
207 s_util.c[0] = *(u_int8_t *)w;
208 }
209 if (len)
210 printf("cksum4: out of data\n");
211 if (mlen == -1) {
212 /* The last mbuf has odd # of bytes. Follow the
213 standard (the odd byte may be shifted left by 8 bits
214 or not as determined by endian-ness of the machine) */
215 s_util.c[1] = 0;
216 sum += s_util.s;
217 }
218 REDUCE;
219 return (~sum & 0xffff);
220 }
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