1 /* $OpenBSD: in4_cksum.c,v 1.11 2022/02/01 15:30:10 miod 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 <sys/socketvar.h>
70 #include <netinet/in.h>
71 #include <netinet/ip.h>
72 #include <netinet/ip_var.h>
73
74 /*
75 * Checksum routine for Internet Protocol family headers (Portable Version).
76 * This is only for IPv4 pseudo header checksum.
77 * No need to clear non-pseudo-header fields in IPv4 header.
78 * len is for actual payload size, and does not include IPv4 header and
79 * skipped header chain (off + len should be equal to the whole packet).
80 *
81 * This routine is very heavily used in the network
82 * code and should be modified for each CPU to be as fast as possible.
83 */
84
85 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
86 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
87
88 int
89 in4_cksum(struct mbuf *m, u_int8_t nxt, int off, int len)
90 {
91 u_int16_t *w;
92 int sum = 0;
93 int mlen = 0;
94 int byte_swapped = 0;
95 union {
96 struct ipovly ipov;
97 u_int16_t w[10];
98 } u;
99 union {
100 u_int8_t c[2];
101 u_int16_t s;
102 } s_util;
103 union {
104 u_int16_t s[2];
105 u_int32_t l;
106 } l_util;
107
108 if (nxt != 0) {
109 /* pseudo header */
110 if (off < sizeof(struct ipovly))
111 panic("in4_cksum: offset too short");
112 if (m->m_len < sizeof(struct ip))
113 panic("in4_cksum: bad mbuf chain");
114 u.ipov.ih_x1[8] = 0;
115 u.ipov.ih_pr = nxt;
116 u.ipov.ih_len = htons(len);
117 u.ipov.ih_src = mtod(m, struct ip *)->ip_src;
118 u.ipov.ih_dst = mtod(m, struct ip *)->ip_dst;
119 w = u.w;
120 /* assumes sizeof(ipov) == 20 and first 8 bytes are zeroes */
121 sum += w[4]; sum += w[5]; sum += w[6];
122 sum += w[7]; sum += w[8]; sum += w[9];
123 }
124
125 /* skip unnecessary part */
126 while (m && off > 0) {
127 if (m->m_len > off)
128 break;
129 off -= m->m_len;
130 m = m->m_next;
131 }
132
133 for (;m && len; m = m->m_next) {
134 if (m->m_len == 0)
135 continue;
136 w = (u_int16_t *)(mtod(m, caddr_t) + off);
137 if (mlen == -1) {
138 /*
139 * The first byte of this mbuf is the continuation
140 * of a word spanning between this mbuf and the
141 * last mbuf.
142 *
143 * s_util.c[0] is already saved when scanning previous
144 * mbuf.
145 */
146 s_util.c[1] = *(u_int8_t *)w;
147 sum += s_util.s;
148 w = (u_int16_t *)((u_int8_t *)w + 1);
149 mlen = m->m_len - off - 1;
150 len--;
151 } else
152 mlen = m->m_len - off;
153 off = 0;
154 if (len < mlen)
155 mlen = len;
156 len -= mlen;
157 /*
158 * Force to even boundary.
159 */
160 if ((1 & (long) w) && (mlen > 0)) {
161 REDUCE;
162 sum <<= 8;
163 s_util.c[0] = *(u_int8_t *)w;
164 w = (u_int16_t *)((int8_t *)w + 1);
165 mlen--;
166 byte_swapped = 1;
167 }
168 /*
169 * Unroll the loop to make overhead from
170 * branches &c small.
171 */
172 while ((mlen -= 32) >= 0) {
173 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
174 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
175 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
176 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
177 w += 16;
178 }
179 mlen += 32;
180 while ((mlen -= 8) >= 0) {
181 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
182 w += 4;
183 }
184 mlen += 8;
185 if (mlen == 0 && byte_swapped == 0)
186 continue;
187 REDUCE;
188 while ((mlen -= 2) >= 0) {
189 sum += *w++;
190 }
191 if (byte_swapped) {
192 REDUCE;
193 sum <<= 8;
194 byte_swapped = 0;
195 if (mlen == -1) {
196 s_util.c[1] = *(u_int8_t *)w;
197 sum += s_util.s;
198 mlen = 0;
199 } else
200 mlen = -1;
201 } else if (mlen == -1)
202 s_util.c[0] = *(u_int8_t *)w;
203 }
204 if (len)
205 printf("cksum4: out of data\n");
206 if (mlen == -1) {
207 /* The last mbuf has odd # of bytes. Follow the
208 standard (the odd byte may be shifted left by 8 bits
209 or not as determined by endian-ness of the machine) */
210 s_util.c[1] = 0;
211 sum += s_util.s;
212 }
213 REDUCE;
214 return (~sum & 0xffff);
215 }
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