1/* $NetBSD: in_cksum.c,v 1.7 1997/09/02 13:18:15 thorpej Exp $ */ 2 3/*- 4 * Copyright (c) 1988, 1992, 1993 5 * The Regents of the University of California. All rights reserved. 6 * Copyright (c) 1996 7 * Matt Thomas <matt@3am-software.com> 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by the University of 20 * California, Berkeley and its contributors. 21 * 4. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93 38 */ 39 40#include <sys/cdefs.h> /* RCS ID & Copyright macro defns */ 41__FBSDID("$FreeBSD$"); 42 43#include <sys/param.h> 44#include <sys/mbuf.h> 45#include <sys/systm.h> 46#include <netinet/in_systm.h> 47#include <netinet/in.h> 48#include <netinet/ip.h> 49#include <machine/in_cksum.h> 50 51/* 52 * Checksum routine for Internet Protocol family headers 53 * (Portable Alpha version). 54 * 55 * This routine is very heavily used in the network 56 * code and should be modified for each CPU to be as fast as possible. 57 */ 58 59#define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) 60#define REDUCE32 \ 61 { \ 62 q_util.q = sum; \ 63 sum = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \ 64 } 65#define REDUCE16 \ 66 { \ 67 q_util.q = sum; \ 68 l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \ 69 sum = l_util.s[0] + l_util.s[1]; \ 70 ADDCARRY(sum); \ 71 } 72 73union l_util { 74 u_int16_t s[2]; 75 u_int32_t l; 76}; 77union q_util { 78 u_int16_t s[4]; 79 u_int32_t l[2]; 80 u_int64_t q; 81}; 82 83u_short 84in_addword(u_short a, u_short b) 85{ 86 u_int64_t sum = a + b; 87 88 ADDCARRY(sum); 89 return (sum); 90} 91 92static 93uint64_t _do_cksum(void *addr, int len) 94{ 95 uint64_t sum; 96 union q_util q_util; 97 98 sum = do_cksum(addr, len); 99 REDUCE32; 100 return (sum); 101} 102 103u_short 104in_cksum_skip(struct mbuf *m, int len, int skip) 105{ 106 u_int64_t sum = 0; 107 int mlen = 0; 108 int clen = 0; 109 caddr_t addr; 110 union q_util q_util; 111 union l_util l_util; 112 113 len -= skip; 114 for (; skip && m; m = m->m_next) { 115 if (m->m_len > skip) { 116 mlen = m->m_len - skip; 117 addr = mtod(m, caddr_t) + skip; 118 goto skip_start; 119 } else { 120 skip -= m->m_len; 121 } 122 } 123 124 for (; m && len; m = m->m_next) { 125 if (m->m_len == 0) 126 continue; 127 mlen = m->m_len; 128 addr = mtod(m, caddr_t); 129skip_start: 130 if (len < mlen) 131 mlen = len; 132 133 if ((clen ^ (int) addr) & 1) 134 sum += _do_cksum(addr, mlen) << 8; 135 else 136 sum += _do_cksum(addr, mlen); 137 138 clen += mlen; 139 len -= mlen; 140 } 141 REDUCE16; 142 return (~sum & 0xffff); 143} 144 145u_int in_cksum_hdr(const struct ip *ip) 146{ 147 u_int64_t sum = do_cksum(ip, sizeof(struct ip)); 148 union q_util q_util; 149 union l_util l_util; 150 REDUCE16; 151 return (~sum & 0xffff); 152} 153