1 /*
2 * Copyright (c) 2000-2018 Apple Inc. All rights reserved.
3 *
4 * @APPLE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. Please obtain a copy of the License at
10 * http://www.opensource.apple.com/apsl/ and read it before using this
11 * file.
12 *
13 * The Original Code and all software distributed under the License are
14 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
15 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
16 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
18 * Please see the License for the specific language governing rights and
19 * limitations under the License.
20 *
21 * @APPLE_LICENSE_HEADER_END@
22 */
23
24 /*
25 * Copyright (c) 1988, 1992, 1993
26 * The Regents of the University of California. All rights reserved.
27 *
28 * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93
29 */
30
31 #include <sys/param.h>
32 #include "in_cksum.h"
33
34 typedef union {
35 char c[2];
36 u_short s;
37 } short_union_t;
38
39 typedef union {
40 u_short s[2];
41 long l;
42 } long_union_t;
43
44 static __inline__ void
reduce(int * sum)45 reduce(int * sum)
46 {
47 long_union_t l_util;
48
49 l_util.l = *sum;
50 *sum = l_util.s[0] + l_util.s[1];
51 if (*sum > 65535) {
52 *sum -= 65535;
53 }
54 return;
55 }
56
57
58 #include <stdio.h>
59
60 unsigned short
in_cksum(void * pkt,int len)61 in_cksum(void * pkt, int len)
62 {
63 u_short * w;
64 int sum = 0;
65
66 w = (u_short *)pkt;
67 while ((len -= 32) >= 0) {
68 sum += w[0]; sum += w[1];
69 sum += w[2]; sum += w[3];
70 sum += w[4]; sum += w[5];
71 sum += w[6]; sum += w[7];
72 sum += w[8]; sum += w[9];
73 sum += w[10]; sum += w[11];
74 sum += w[12]; sum += w[13];
75 sum += w[14]; sum += w[15];
76 w += 16;
77 }
78 len += 32;
79 while ((len -= 8) >= 0) {
80 sum += w[0]; sum += w[1];
81 sum += w[2]; sum += w[3];
82 w += 4;
83 }
84 len += 8;
85 if (len) {
86 reduce(&sum);
87 while ((len -= 2) >= 0) {
88 sum += *w++;
89 }
90 }
91 if (len == -1) { /* odd-length packet */
92 short_union_t s_util;
93
94 s_util.s = 0;
95 s_util.c[0] = *((char *)w);
96 s_util.c[1] = 0;
97 sum += s_util.s;
98 }
99 reduce(&sum);
100 return ~sum & 0xffff;
101 }
102