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/*
* This file was originally taken from the FreeBSD project.
*
* Copyright (c) 2001 Charles Mott <cm@linktel.net>
* Copyright (c) 2008 coresystems GmbH
* All rights reserved.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <common.h>
#include <net.h>
unsigned compute_ip_checksum(const void *vptr, unsigned nbytes)
{
int sum, oddbyte;
const unsigned short *ptr = vptr;
sum = 0;
while (nbytes > 1) {
sum += *ptr++;
nbytes -= 2;
}
if (nbytes == 1) {
oddbyte = 0;
((u8 *)&oddbyte)[0] = *(u8 *)ptr;
((u8 *)&oddbyte)[1] = 0;
sum += oddbyte;
}
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
sum = ~sum & 0xffff;
return sum;
}
unsigned add_ip_checksums(unsigned offset, unsigned sum, unsigned new)
{
unsigned long checksum;
sum = ~sum & 0xffff;
new = ~new & 0xffff;
if (offset & 1) {
/*
* byte-swap the sum if it came from an odd offset; since the
* computation is endian independant this works.
*/
new = ((new >> 8) & 0xff) | ((new << 8) & 0xff00);
}
checksum = sum + new;
if (checksum > 0xffff)
checksum -= 0xffff;
return (~checksum) & 0xffff;
}
int ip_checksum_ok(const void *addr, unsigned nbytes)
{
return !(compute_ip_checksum(addr, nbytes) & 0xfffe);
}
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