/* $OpenBSD: in_cksum.c,v 1.3 2007/01/08 19:32:39 deraadt Exp $ */ /* $NetBSD: in_cksum.c,v 1.3 1995/04/22 13:53:48 cgd Exp $ */ /* * Copyright (c) 1992 Regents of the University of California. * All rights reserved. * * This software was developed by the Computer Systems Engineering group * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and * contributed to Berkeley. * * 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. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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. * * @(#) Header: in_cksum.c,v 1.1 92/09/11 01:15:55 leres Exp (LBL) */ #include <sys/types.h> #include "dvmrpd.h" #include "log.h" /* * Checksum routine for Internet Protocol family headers. * This routine is very heavily used in the network * code and should be modified for each CPU to be as fast as possible. * In particular, it should not be this one. */ u_int16_t in_cksum(void *p, size_t l) { unsigned int sum = 0; int len; u_char *cp = p; /* ensure that < 2^16 bytes being summed */ if (l >= (1 << 16)) fatalx("in_cksum: packet to big"); len = (int)l; if (((long)cp & 1) == 0) { while (len > 1) { sum += htons(*(u_short *)cp); cp += 2; len -= 2; } } else { while (len > 1) { sum += *cp++ << 8; sum += *cp++; len -= 2; } } if (len == 1) sum += *cp << 8; sum = (sum >> 16) + (sum & 0xffff); /* add in accumulated carries */ sum += sum >> 16; /* add potential last carry */ sum = ntohs(sum); return (0xffff & ~sum); }