1*4882a593Smuzhiyun /*
2*4882a593Smuzhiyun * This file was originally taken from the FreeBSD project.
3*4882a593Smuzhiyun *
4*4882a593Smuzhiyun * Copyright (c) 2001 Charles Mott <cm@linktel.net>
5*4882a593Smuzhiyun * Copyright (c) 2008 coresystems GmbH
6*4882a593Smuzhiyun * All rights reserved.
7*4882a593Smuzhiyun *
8*4882a593Smuzhiyun * SPDX-License-Identifier: BSD-2-Clause
9*4882a593Smuzhiyun */
10*4882a593Smuzhiyun
11*4882a593Smuzhiyun #include <common.h>
12*4882a593Smuzhiyun #include <net.h>
13*4882a593Smuzhiyun
compute_ip_checksum(const void * vptr,unsigned nbytes)14*4882a593Smuzhiyun unsigned compute_ip_checksum(const void *vptr, unsigned nbytes)
15*4882a593Smuzhiyun {
16*4882a593Smuzhiyun int sum, oddbyte;
17*4882a593Smuzhiyun const unsigned short *ptr = vptr;
18*4882a593Smuzhiyun
19*4882a593Smuzhiyun sum = 0;
20*4882a593Smuzhiyun while (nbytes > 1) {
21*4882a593Smuzhiyun sum += *ptr++;
22*4882a593Smuzhiyun nbytes -= 2;
23*4882a593Smuzhiyun }
24*4882a593Smuzhiyun if (nbytes == 1) {
25*4882a593Smuzhiyun oddbyte = 0;
26*4882a593Smuzhiyun ((u8 *)&oddbyte)[0] = *(u8 *)ptr;
27*4882a593Smuzhiyun ((u8 *)&oddbyte)[1] = 0;
28*4882a593Smuzhiyun sum += oddbyte;
29*4882a593Smuzhiyun }
30*4882a593Smuzhiyun sum = (sum >> 16) + (sum & 0xffff);
31*4882a593Smuzhiyun sum += (sum >> 16);
32*4882a593Smuzhiyun sum = ~sum & 0xffff;
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun return sum;
35*4882a593Smuzhiyun }
36*4882a593Smuzhiyun
add_ip_checksums(unsigned offset,unsigned sum,unsigned new)37*4882a593Smuzhiyun unsigned add_ip_checksums(unsigned offset, unsigned sum, unsigned new)
38*4882a593Smuzhiyun {
39*4882a593Smuzhiyun unsigned long checksum;
40*4882a593Smuzhiyun
41*4882a593Smuzhiyun sum = ~sum & 0xffff;
42*4882a593Smuzhiyun new = ~new & 0xffff;
43*4882a593Smuzhiyun if (offset & 1) {
44*4882a593Smuzhiyun /*
45*4882a593Smuzhiyun * byte-swap the sum if it came from an odd offset; since the
46*4882a593Smuzhiyun * computation is endian independant this works.
47*4882a593Smuzhiyun */
48*4882a593Smuzhiyun new = ((new >> 8) & 0xff) | ((new << 8) & 0xff00);
49*4882a593Smuzhiyun }
50*4882a593Smuzhiyun checksum = sum + new;
51*4882a593Smuzhiyun if (checksum > 0xffff)
52*4882a593Smuzhiyun checksum -= 0xffff;
53*4882a593Smuzhiyun
54*4882a593Smuzhiyun return (~checksum) & 0xffff;
55*4882a593Smuzhiyun }
56*4882a593Smuzhiyun
ip_checksum_ok(const void * addr,unsigned nbytes)57*4882a593Smuzhiyun int ip_checksum_ok(const void *addr, unsigned nbytes)
58*4882a593Smuzhiyun {
59*4882a593Smuzhiyun return !(compute_ip_checksum(addr, nbytes) & 0xfffe);
60*4882a593Smuzhiyun }
61