1 /* $NetBSD: in_cksum.c,v 1.7 1997/09/02 13:18:15 thorpej Exp $ */ 2 3 /*- 4 * SPDX-License-Identifier: BSD-4-Clause 5 * 6 * Copyright (c) 1988, 1992, 1993 7 * The Regents of the University of California. All rights reserved. 8 * Copyright (c) 1996 9 * Matt Thomas <matt@3am-software.com> 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 * 39 * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93 40 */ 41 42 #include <sys/cdefs.h> /* RCS ID & Copyright macro defns */ 43 __FBSDID("$FreeBSD$"); 44 45 #include <sys/param.h> 46 #include <sys/mbuf.h> 47 #include <sys/systm.h> 48 #include <netinet/in_systm.h> 49 #include <netinet/in.h> 50 #include <netinet/ip.h> 51 #include <machine/in_cksum.h> 52 53 /* 54 * Checksum routine for Internet Protocol family headers 55 * (Portable Alpha version). 56 * 57 * This routine is very heavily used in the network 58 * code and should be modified for each CPU to be as fast as possible. 59 */ 60 61 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) 62 #define REDUCE32 \ 63 { \ 64 q_util.q = sum; \ 65 sum = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \ 66 } 67 #define REDUCE16 \ 68 { \ 69 q_util.q = sum; \ 70 l_util.l = q_util.s[0] + q_util.s[1] + q_util.s[2] + q_util.s[3]; \ 71 sum = l_util.s[0] + l_util.s[1]; \ 72 ADDCARRY(sum); \ 73 } 74 75 union l_util { 76 u_int16_t s[2]; 77 u_int32_t l; 78 }; 79 union q_util { 80 u_int16_t s[4]; 81 u_int32_t l[2]; 82 u_int64_t q; 83 }; 84 85 u_short 86 in_addword(u_short a, u_short b) 87 { 88 u_int64_t sum = a + b; 89 90 ADDCARRY(sum); 91 return (sum); 92 } 93 94 static 95 uint64_t _do_cksum(void *addr, int len) 96 { 97 uint64_t sum; 98 union q_util q_util; 99 100 sum = do_cksum(addr, len); 101 REDUCE32; 102 return (sum); 103 } 104 105 u_short 106 in_cksum_skip(struct mbuf *m, int len, int skip) 107 { 108 u_int64_t sum = 0; 109 int mlen = 0; 110 int clen = 0; 111 caddr_t addr; 112 union q_util q_util; 113 union l_util l_util; 114 115 len -= skip; 116 for (; skip && m; m = m->m_next) { 117 if (m->m_len > skip) { 118 mlen = m->m_len - skip; 119 addr = mtod(m, caddr_t) + skip; 120 goto skip_start; 121 } else { 122 skip -= m->m_len; 123 } 124 } 125 126 for (; m && len; m = m->m_next) { 127 if (m->m_len == 0) 128 continue; 129 mlen = m->m_len; 130 addr = mtod(m, caddr_t); 131 skip_start: 132 if (len < mlen) 133 mlen = len; 134 135 if ((clen ^ (int) addr) & 1) 136 sum += _do_cksum(addr, mlen) << 8; 137 else 138 sum += _do_cksum(addr, mlen); 139 140 clen += mlen; 141 len -= mlen; 142 } 143 REDUCE16; 144 return (~sum & 0xffff); 145 } 146 147 u_int in_cksum_hdr(const struct ip *ip) 148 { 149 u_int64_t sum = do_cksum(ip, sizeof(struct ip)); 150 union q_util q_util; 151 union l_util l_util; 152 REDUCE16; 153 return (~sum & 0xffff); 154 } 155