1/* $OpenBSD: in4_cksum.c,v 1.11 2022/02/01 15:30:10 miod 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 <sys/socketvar.h> 70#include <netinet/in.h> 71#include <netinet/ip.h> 72#include <netinet/ip_var.h> 73 74/* 75 * Checksum routine for Internet Protocol family headers (Portable Version). 76 * This is only for IPv4 pseudo header checksum. 77 * No need to clear non-pseudo-header fields in IPv4 header. 78 * len is for actual payload size, and does not include IPv4 header and 79 * skipped header chain (off + len should be equal to the whole packet). 80 * 81 * This routine is very heavily used in the network 82 * code and should be modified for each CPU to be as fast as possible. 83 */ 84 85#define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) 86#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} 87 88int 89in4_cksum(struct mbuf *m, u_int8_t nxt, int off, int len) 90{ 91 u_int16_t *w; 92 int sum = 0; 93 int mlen = 0; 94 int byte_swapped = 0; 95 union { 96 struct ipovly ipov; 97 u_int16_t w[10]; 98 } u; 99 union { 100 u_int8_t c[2]; 101 u_int16_t s; 102 } s_util; 103 union { 104 u_int16_t s[2]; 105 u_int32_t l; 106 } l_util; 107 108 if (nxt != 0) { 109 /* pseudo header */ 110 if (off < sizeof(struct ipovly)) 111 panic("in4_cksum: offset too short"); 112 if (m->m_len < sizeof(struct ip)) 113 panic("in4_cksum: bad mbuf chain"); 114 u.ipov.ih_x1[8] = 0; 115 u.ipov.ih_pr = nxt; 116 u.ipov.ih_len = htons(len); 117 u.ipov.ih_src = mtod(m, struct ip *)->ip_src; 118 u.ipov.ih_dst = mtod(m, struct ip *)->ip_dst; 119 w = u.w; 120 /* assumes sizeof(ipov) == 20 and first 8 bytes are zeroes */ 121 sum += w[4]; sum += w[5]; sum += w[6]; 122 sum += w[7]; sum += w[8]; sum += w[9]; 123 } 124 125 /* skip unnecessary part */ 126 while (m && off > 0) { 127 if (m->m_len > off) 128 break; 129 off -= m->m_len; 130 m = m->m_next; 131 } 132 133 for (;m && len; m = m->m_next) { 134 if (m->m_len == 0) 135 continue; 136 w = (u_int16_t *)(mtod(m, caddr_t) + off); 137 if (mlen == -1) { 138 /* 139 * The first byte of this mbuf is the continuation 140 * of a word spanning between this mbuf and the 141 * last mbuf. 142 * 143 * s_util.c[0] is already saved when scanning previous 144 * mbuf. 145 */ 146 s_util.c[1] = *(u_int8_t *)w; 147 sum += s_util.s; 148 w = (u_int16_t *)((u_int8_t *)w + 1); 149 mlen = m->m_len - off - 1; 150 len--; 151 } else 152 mlen = m->m_len - off; 153 off = 0; 154 if (len < mlen) 155 mlen = len; 156 len -= mlen; 157 /* 158 * Force to even boundary. 159 */ 160 if ((1 & (long) w) && (mlen > 0)) { 161 REDUCE; 162 sum <<= 8; 163 s_util.c[0] = *(u_int8_t *)w; 164 w = (u_int16_t *)((int8_t *)w + 1); 165 mlen--; 166 byte_swapped = 1; 167 } 168 /* 169 * Unroll the loop to make overhead from 170 * branches &c small. 171 */ 172 while ((mlen -= 32) >= 0) { 173 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 174 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 175 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 176 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 177 w += 16; 178 } 179 mlen += 32; 180 while ((mlen -= 8) >= 0) { 181 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 182 w += 4; 183 } 184 mlen += 8; 185 if (mlen == 0 && byte_swapped == 0) 186 continue; 187 REDUCE; 188 while ((mlen -= 2) >= 0) { 189 sum += *w++; 190 } 191 if (byte_swapped) { 192 REDUCE; 193 sum <<= 8; 194 byte_swapped = 0; 195 if (mlen == -1) { 196 s_util.c[1] = *(u_int8_t *)w; 197 sum += s_util.s; 198 mlen = 0; 199 } else 200 mlen = -1; 201 } else if (mlen == -1) 202 s_util.c[0] = *(u_int8_t *)w; 203 } 204 if (len) 205 printf("cksum4: out of data\n"); 206 if (mlen == -1) { 207 /* The last mbuf has odd # of bytes. Follow the 208 standard (the odd byte may be shifted left by 8 bits 209 or not as determined by endian-ness of the machine) */ 210 s_util.c[1] = 0; 211 sum += s_util.s; 212 } 213 REDUCE; 214 return (~sum & 0xffff); 215} 216