in4_cksum.c revision 126259
1/* $OpenBSD: in4_cksum.c,v 1.7 2003/06/02 23:28:13 millert Exp $ */ 2/* $KAME: in4_cksum.c,v 1.10 2001/11/30 10:06:15 itojun Exp $ */ 3/* $NetBSD: in_cksum.c,v 1.13 1996/10/13 02:03:03 christos Exp $ */ 4 5/* 6 * Copyright (C) 1999 WIDE Project. 7 * All rights reserved. 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. Neither the name of the project nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34/* 35 * Copyright (c) 1988, 1992, 1993 36 * The Regents of the University of California. All rights reserved. 37 * 38 * Redistribution and use in source and binary forms, with or without 39 * modification, are permitted provided that the following conditions 40 * are met: 41 * 1. Redistributions of source code must retain the above copyright 42 * notice, this list of conditions and the following disclaimer. 43 * 2. Redistributions in binary form must reproduce the above copyright 44 * notice, this list of conditions and the following disclaimer in the 45 * documentation and/or other materials provided with the distribution. 46 * 3. Neither the name of the University nor the names of its contributors 47 * may be used to endorse or promote products derived from this software 48 * without specific prior written permission. 49 * 50 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 51 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 52 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 53 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 54 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 55 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 56 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 57 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 58 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 59 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 60 * SUCH DAMAGE. 61 * 62 * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93 63 */ 64 65#include <sys/param.h> 66#include <sys/mbuf.h> 67#include <sys/systm.h> 68#include <sys/socket.h> 69#include <net/route.h> 70#include <netinet/in.h> 71#include <netinet/in_systm.h> 72#include <netinet/ip.h> 73#include <netinet/ip_var.h> 74 75/* 76 * Checksum routine for Internet Protocol family headers (Portable Version). 77 * This is only for IPv4 pseudo header checksum. 78 * No need to clear non-pseudo-header fields in IPv4 header. 79 * len is for actual payload size, and does not include IPv4 header and 80 * skipped header chain (off + len should be equal to the whole packet). 81 * 82 * This routine is very heavily used in the network 83 * code and should be modified for each CPU to be as fast as possible. 84 */ 85 86#define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) 87#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} 88 89int 90in4_cksum(m, nxt, off, len) 91 struct mbuf *m; 92 u_int8_t nxt; 93 int off, len; 94{ 95 u_int16_t *w; 96 int sum = 0; 97 int mlen = 0; 98 int byte_swapped = 0; 99 union { 100 struct ipovly ipov; 101 u_int16_t w[10]; 102 } u; 103 union { 104 u_int8_t c[2]; 105 u_int16_t s; 106 } s_util; 107 union { 108 u_int16_t s[2]; 109 u_int32_t l; 110 } l_util; 111 112 if (nxt != 0) { 113 /* pseudo header */ 114 if (off < sizeof(struct ipovly)) 115 panic("in4_cksum: offset too short"); 116 if (m->m_len < sizeof(struct ip)) 117 panic("in4_cksum: bad mbuf chain"); 118 bzero(&u.ipov, sizeof(u.ipov)); 119 u.ipov.ih_len = htons(len); 120 u.ipov.ih_pr = nxt; 121 u.ipov.ih_src = mtod(m, struct ip *)->ip_src; 122 u.ipov.ih_dst = mtod(m, struct ip *)->ip_dst; 123 w = u.w; 124 /* assumes sizeof(ipov) == 20 */ 125 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; sum += w[4]; 126 sum += w[5]; sum += w[6]; sum += w[7]; sum += w[8]; sum += w[9]; 127 } 128 129 /* skip unnecessary part */ 130 while (m && off > 0) { 131 if (m->m_len > off) 132 break; 133 off -= m->m_len; 134 m = m->m_next; 135 } 136 137 for (;m && len; m = m->m_next) { 138 if (m->m_len == 0) 139 continue; 140 w = (u_int16_t *)(mtod(m, caddr_t) + off); 141 if (mlen == -1) { 142 /* 143 * The first byte of this mbuf is the continuation 144 * of a word spanning between this mbuf and the 145 * last mbuf. 146 * 147 * s_util.c[0] is already saved when scanning previous 148 * mbuf. 149 */ 150 s_util.c[1] = *(u_int8_t *)w; 151 sum += s_util.s; 152 w = (u_int16_t *)((u_int8_t *)w + 1); 153 mlen = m->m_len - off - 1; 154 len--; 155 } else 156 mlen = m->m_len - off; 157 off = 0; 158 if (len < mlen) 159 mlen = len; 160 len -= mlen; 161 /* 162 * Force to even boundary. 163 */ 164 if ((1 & (long) w) && (mlen > 0)) { 165 REDUCE; 166 sum <<= 8; 167 s_util.c[0] = *(u_int8_t *)w; 168 w = (u_int16_t *)((int8_t *)w + 1); 169 mlen--; 170 byte_swapped = 1; 171 } 172 /* 173 * Unroll the loop to make overhead from 174 * branches &c small. 175 */ 176 while ((mlen -= 32) >= 0) { 177 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 178 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 179 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 180 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 181 w += 16; 182 } 183 mlen += 32; 184 while ((mlen -= 8) >= 0) { 185 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 186 w += 4; 187 } 188 mlen += 8; 189 if (mlen == 0 && byte_swapped == 0) 190 continue; 191 REDUCE; 192 while ((mlen -= 2) >= 0) { 193 sum += *w++; 194 } 195 if (byte_swapped) { 196 REDUCE; 197 sum <<= 8; 198 byte_swapped = 0; 199 if (mlen == -1) { 200 s_util.c[1] = *(u_int8_t *)w; 201 sum += s_util.s; 202 mlen = 0; 203 } else 204 mlen = -1; 205 } else if (mlen == -1) 206 s_util.c[0] = *(u_int8_t *)w; 207 } 208 if (len) 209 printf("cksum4: out of data\n"); 210 if (mlen == -1) { 211 /* The last mbuf has odd # of bytes. Follow the 212 standard (the odd byte may be shifted left by 8 bits 213 or not as determined by endian-ness of the machine) */ 214 s_util.c[1] = 0; 215 sum += s_util.s; 216 } 217 REDUCE; 218 return (~sum & 0xffff); 219} 220