/* * 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); }