/* * This file is part of the libpayload project. * * It has originally been taken from the FreeBSD project. * * Copyright (c) 2001 Charles Mott <cm@linktel.net> * Copyright (c) 2008 coresystems GmbH * 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. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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. */ #include <libpayload.h> unsigned short ipchksum(const void *vptr, unsigned long 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); return (~sum); }