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1 | /* |
2 | * Copyright (c) 1988 Regents of the University of California. | |
3 | * All rights reserved. | |
4 | * | |
5 | * Redistribution and use in source and binary forms, with or without | |
6 | * modification, are permitted provided that the following conditions | |
7 | * are met: | |
8 | * 1. Redistributions of source code must retain the above copyright | |
9 | * notice, this list of conditions and the following disclaimer. | |
10 | * 2. Redistributions in binary form must reproduce the above copyright | |
11 | * notice, this list of conditions and the following disclaimer in the | |
12 | * documentation and/or other materials provided with the distribution. | |
13 | * 3. All advertising materials mentioning features or use of this software | |
14 | * must display the following acknowledgement: | |
15 | * This product includes software developed by the University of | |
16 | * California, Berkeley and its contributors. | |
17 | * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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 | * @(#)in_cksum.c 7.3 (Berkeley) 6/28/90 | |
34 | */ | |
35 | ||
36 | #include "../h/types.h" | |
37 | #include "../h/mbuf.h" | |
38 | ||
39 | /* | |
40 | * Checksum routine for Internet Protocol family headers (Portable Version). | |
41 | * | |
42 | * This routine is very heavily used in the network | |
43 | * code and should be modified for each CPU to be as fast as possible. | |
44 | */ | |
45 | ||
46 | #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) | |
47 | #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} | |
48 | ||
49 | in_cksum_c(m, len) | |
50 | register struct mbuf *m; | |
51 | register int len; | |
52 | { | |
53 | register u_short *w; | |
54 | register int sum = 0; | |
55 | register int mlen = 0; | |
56 | int byte_swapped = 0; | |
57 | ||
58 | union { | |
59 | char c[2]; | |
60 | u_short s; | |
61 | } s_util; | |
62 | union { | |
63 | u_short s[2]; | |
64 | long l; | |
65 | } l_util; | |
66 | ||
67 | for (;m && len; m = m->m_next) { | |
68 | if (m->m_len == 0) | |
69 | continue; | |
70 | w = mtod(m, u_short *); | |
71 | if (mlen == -1) { | |
72 | /* | |
73 | * The first byte of this mbuf is the continuation | |
74 | * of a word spanning between this mbuf and the | |
75 | * last mbuf. | |
76 | * | |
77 | * s_util.c[0] is already saved when scanning previous | |
78 | * mbuf. | |
79 | */ | |
80 | s_util.c[1] = *(char *)w; | |
81 | sum += s_util.s; | |
82 | w = (u_short *)((char *)w + 1); | |
83 | mlen = m->m_len - 1; | |
84 | len--; | |
85 | } else | |
86 | mlen = m->m_len; | |
87 | if (len < mlen) | |
88 | mlen = len; | |
89 | len -= mlen; | |
90 | /* | |
91 | * Force to even boundary. | |
92 | */ | |
93 | if ((1 & (int) w) && (mlen > 0)) { | |
94 | REDUCE; | |
95 | sum <<= 8; | |
96 | s_util.c[0] = *(u_char *)w; | |
97 | w = (u_short *)((char *)w + 1); | |
98 | mlen--; | |
99 | byte_swapped = 1; | |
100 | } | |
101 | /* | |
102 | * Unroll the loop to make overhead from | |
103 | * branches &c small. | |
104 | */ | |
105 | while ((mlen -= 32) >= 0) { | |
106 | sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; | |
107 | sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; | |
108 | sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; | |
109 | sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; | |
110 | w += 16; | |
111 | } | |
112 | mlen += 32; | |
113 | while ((mlen -= 8) >= 0) { | |
114 | sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; | |
115 | w += 4; | |
116 | } | |
117 | mlen += 8; | |
118 | if (mlen == 0 && byte_swapped == 0) | |
119 | continue; | |
120 | REDUCE; | |
121 | while ((mlen -= 2) >= 0) { | |
122 | sum += *w++; | |
123 | } | |
124 | if (byte_swapped) { | |
125 | REDUCE; | |
126 | sum <<= 8; | |
127 | byte_swapped = 0; | |
128 | if (mlen == -1) { | |
129 | s_util.c[1] = *(char *)w; | |
130 | sum += s_util.s; | |
131 | mlen = 0; | |
132 | } else | |
133 | mlen = -1; | |
134 | } else if (mlen == -1) | |
135 | s_util.c[0] = *(char *)w; | |
136 | } | |
137 | if (len) | |
138 | printf("cksum: out of data\n"); | |
139 | if (mlen == -1) { | |
140 | /* The last mbuf has odd # of bytes. Follow the | |
141 | standard (the odd byte may be shifted left by 8 bits | |
142 | or not as determined by endian-ness of the machine) */ | |
143 | s_util.c[1] = 0; | |
144 | sum += s_util.s; | |
145 | } | |
146 | REDUCE; | |
147 | return (~sum & 0xffff); | |
148 | } |