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 #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 73 union l_util { 74 u_int16_t s[2]; 75 u_int32_t l; 76 }; 77 union q_util { 78 u_int16_t s[4]; 79 u_int32_t l[2]; 80 u_int64_t q; 81 }; 82 83 u_short 84 in_addword(u_short a, u_short b) 85 { 86 u_int64_t sum = a + b; 87 88 ADDCARRY(sum); 89 return (sum); 90 } 91 92 static 93 uint64_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 } 102 103 u_short 104 in_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); 129 skip_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 } 144 145 u_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