1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
|
/* $OpenBSD: ns_cksum.c,v 1.4 2001/09/20 17:02:32 mpech Exp $ */
/* $NetBSD: ns_cksum.c,v 1.3 1995/03/08 02:14:53 cgd Exp $ */
/*
* Copyright (c) 1982, 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)ns_cksum.c 8.1 (Berkeley) 6/10/93
*/
#include <sys/param.h>
#include <sys/mbuf.h>
#include <netns/ns_var.h>
/*
* Checksum routine for Network Systems Protocol Packets (Big-Endian).
*
* This routine is very heavily used in the network
* code and should be modified for each CPU to be as fast as possible.
*/
#define ADDCARRY(x) { if ((x) > 65535) (x) -= 65535; }
#define FOLD(x) {l_util.l = (x); (x) = l_util.s[0] + l_util.s[1]; ADDCARRY(x);}
u_short
ns_cksum(m, len)
register struct mbuf *m;
register int len;
{
register u_int16_t *w;
register int sum = 0;
register int mlen = 0;
register int sum2;
union {
u_int16_t s[2];
int32_t l;
} l_util;
for (;m && len; m = m->m_next) {
if (m->m_len == 0)
continue;
/*
* Each trip around loop adds in
* word from one mbuf segment.
*/
w = mtod(m, u_int16_t *);
if (mlen == -1) {
/*
* There is a byte left from the last segment;
* ones-complement add it into the checksum.
*/
#if BYTE_ORDER == BIG_ENDIAN
sum += *(u_char *)w;
#else
sum += *(u_char *)w << 8;
#endif
sum += sum;
w = (u_int16_t *)(1 + (char *)w);
mlen = m->m_len - 1;
len--;
FOLD(sum);
} else
mlen = m->m_len;
if (len < mlen)
mlen = len;
len -= mlen;
/*
* We can do a 16 bit ones complement sum using
* 32 bit arithmetic registers for adding,
* with carries from the low added
* into the high (by normal carry-chaining)
* so long as we fold back before 16 carries have occurred.
*/
if (1 & (long) w)
goto uuuuglyy;
#ifndef TINY
/* -DTINY reduces the size from 1250 to 550, but slows it down by 22% */
while ((mlen -= 32) >= 0) {
sum += w[0]; sum += sum; sum += w[1]; sum += sum;
sum += w[2]; sum += sum; sum += w[3]; sum += sum;
sum += w[4]; sum += sum; sum += w[5]; sum += sum;
sum += w[6]; sum += sum; sum += w[7]; sum += sum;
FOLD(sum);
sum += w[8]; sum += sum; sum += w[9]; sum += sum;
sum += w[10]; sum += sum; sum += w[11]; sum += sum;
sum += w[12]; sum += sum; sum += w[13]; sum += sum;
sum += w[14]; sum += sum; sum += w[15]; sum += sum;
FOLD(sum);
w += 16;
}
mlen += 32;
#endif
while ((mlen -= 8) >= 0) {
sum += w[0]; sum += sum; sum += w[1]; sum += sum;
sum += w[2]; sum += sum; sum += w[3]; sum += sum;
FOLD(sum);
w += 4;
}
mlen += 8;
while ((mlen -= 2) >= 0) {
sum += *w++; sum += sum;
}
goto commoncase;
uuuuglyy:
#if BYTE_ORDER == BIG_ENDIAN
#define ww(n) (((u_char *)w)[n + n + 1])
#define vv(n) (((u_char *)w)[n + n])
#else
#if BYTE_ORDER == LITTLE_ENDIAN
#define vv(n) (((u_char *)w)[n + n + 1])
#define ww(n) (((u_char *)w)[n + n])
#endif
#endif
sum2 = 0;
#ifndef TINY
while ((mlen -= 32) >= 0) {
sum += ww(0); sum += sum; sum += ww(1); sum += sum;
sum += ww(2); sum += sum; sum += ww(3); sum += sum;
sum += ww(4); sum += sum; sum += ww(5); sum += sum;
sum += ww(6); sum += sum; sum += ww(7); sum += sum;
FOLD(sum);
sum += ww(8); sum += sum; sum += ww(9); sum += sum;
sum += ww(10); sum += sum; sum += ww(11); sum += sum;
sum += ww(12); sum += sum; sum += ww(13); sum += sum;
sum += ww(14); sum += sum; sum += ww(15); sum += sum;
FOLD(sum);
sum2 += vv(0); sum2 += sum2; sum2 += vv(1); sum2 += sum2;
sum2 += vv(2); sum2 += sum2; sum2 += vv(3); sum2 += sum2;
sum2 += vv(4); sum2 += sum2; sum2 += vv(5); sum2 += sum2;
sum2 += vv(6); sum2 += sum2; sum2 += vv(7); sum2 += sum2;
FOLD(sum2);
sum2 += vv(8); sum2 += sum2; sum2 += vv(9); sum2 += sum2;
sum2 += vv(10); sum2 += sum2; sum2 += vv(11); sum2 += sum2;
sum2 += vv(12); sum2 += sum2; sum2 += vv(13); sum2 += sum2;
sum2 += vv(14); sum2 += sum2; sum2 += vv(15); sum2 += sum2;
FOLD(sum2);
w += 16;
}
mlen += 32;
#endif
while ((mlen -= 8) >= 0) {
sum += ww(0); sum += sum; sum += ww(1); sum += sum;
sum += ww(2); sum += sum; sum += ww(3); sum += sum;
FOLD(sum);
sum2 += vv(0); sum2 += sum2; sum2 += vv(1); sum2 += sum2;
sum2 += vv(2); sum2 += sum2; sum2 += vv(3); sum2 += sum2;
FOLD(sum2);
w += 4;
}
mlen += 8;
while ((mlen -= 2) >= 0) {
sum += ww(0); sum += sum;
sum2 += vv(0); sum2 += sum2;
w++;
}
sum += (sum2 << 8);
commoncase:
if (mlen == -1) {
#if BYTE_ORDER == BIG_ENDIAN
sum += *(u_char *)w << 8;
#else
sum += *(u_char *)w;
#endif
}
FOLD(sum);
}
if (mlen == -1) {
/* We had an odd number of bytes to sum; assume a garbage
byte of zero and clean up */
sum += sum;
FOLD(sum);
}
/*
* sum has already been kept to low sixteen bits.
* just examine result and exit.
*/
if(sum==0xffff) sum = 0;
return (sum);
}
|
