in4_cksum.c revision 1.2
1 1.2 itojun /* $NetBSD: in4_cksum.c,v 1.2 1999/12/13 15:17:19 itojun Exp $ */ 2 1.2 itojun 3 1.2 itojun /* 4 1.2 itojun * Copyright (C) 1999 WIDE Project. 5 1.2 itojun * All rights reserved. 6 1.2 itojun * 7 1.2 itojun * Redistribution and use in source and binary forms, with or without 8 1.2 itojun * modification, are permitted provided that the following conditions 9 1.2 itojun * are met: 10 1.2 itojun * 1. Redistributions of source code must retain the above copyright 11 1.2 itojun * notice, this list of conditions and the following disclaimer. 12 1.2 itojun * 2. Redistributions in binary form must reproduce the above copyright 13 1.2 itojun * notice, this list of conditions and the following disclaimer in the 14 1.2 itojun * documentation and/or other materials provided with the distribution. 15 1.2 itojun * 3. Neither the name of the project nor the names of its contributors 16 1.2 itojun * may be used to endorse or promote products derived from this software 17 1.2 itojun * without specific prior written permission. 18 1.2 itojun * 19 1.2 itojun * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 20 1.2 itojun * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 1.2 itojun * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 1.2 itojun * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 23 1.2 itojun * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 1.2 itojun * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 1.2 itojun * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 1.2 itojun * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 1.2 itojun * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 1.2 itojun * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 1.2 itojun * SUCH DAMAGE. 30 1.2 itojun */ 31 1.2 itojun 32 1.2 itojun /* 33 1.2 itojun * Copyright (c) 1988, 1992, 1993 34 1.2 itojun * The Regents of the University of California. All rights reserved. 35 1.2 itojun * 36 1.2 itojun * Redistribution and use in source and binary forms, with or without 37 1.2 itojun * modification, are permitted provided that the following conditions 38 1.2 itojun * are met: 39 1.2 itojun * 1. Redistributions of source code must retain the above copyright 40 1.2 itojun * notice, this list of conditions and the following disclaimer. 41 1.2 itojun * 2. Redistributions in binary form must reproduce the above copyright 42 1.2 itojun * notice, this list of conditions and the following disclaimer in the 43 1.2 itojun * documentation and/or other materials provided with the distribution. 44 1.2 itojun * 3. All advertising materials mentioning features or use of this software 45 1.2 itojun * must display the following acknowledgement: 46 1.2 itojun * This product includes software developed by the University of 47 1.2 itojun * California, Berkeley and its contributors. 48 1.2 itojun * 4. Neither the name of the University nor the names of its contributors 49 1.2 itojun * may be used to endorse or promote products derived from this software 50 1.2 itojun * without specific prior written permission. 51 1.2 itojun * 52 1.2 itojun * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 53 1.2 itojun * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 54 1.2 itojun * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 55 1.2 itojun * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 56 1.2 itojun * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 57 1.2 itojun * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 58 1.2 itojun * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 59 1.2 itojun * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 60 1.2 itojun * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 61 1.2 itojun * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 62 1.2 itojun * SUCH DAMAGE. 63 1.2 itojun * 64 1.2 itojun * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93 65 1.2 itojun */ 66 1.2 itojun 67 1.2 itojun #include <sys/param.h> 68 1.2 itojun #include <sys/mbuf.h> 69 1.2 itojun #include <sys/systm.h> 70 1.2 itojun #include <sys/socket.h> 71 1.2 itojun #include <net/route.h> 72 1.2 itojun #include <netinet/in.h> 73 1.2 itojun #include <netinet/in_systm.h> 74 1.2 itojun #include <netinet/ip.h> 75 1.2 itojun #include <netinet/ip_var.h> 76 1.2 itojun 77 1.2 itojun /* 78 1.2 itojun * Checksum routine for Internet Protocol family headers (Portable Version). 79 1.2 itojun * This is only for IPv4 pseudo header checksum. 80 1.2 itojun * No need to clear non-pseudo-header fields in IPv4 header. 81 1.2 itojun * len is for actual payload size, and does not include IPv4 header and 82 1.2 itojun * skipped header chain (off + len should be equal to the whole packet). 83 1.2 itojun * 84 1.2 itojun * This routine is very heavily used in the network 85 1.2 itojun * code and should be modified for each CPU to be as fast as possible. 86 1.2 itojun */ 87 1.2 itojun 88 1.2 itojun #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) 89 1.2 itojun #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} 90 1.2 itojun 91 1.2 itojun int 92 1.2 itojun in4_cksum(m, nxt, off, len) 93 1.2 itojun register struct mbuf *m; 94 1.2 itojun u_int8_t nxt; 95 1.2 itojun register int off, len; 96 1.2 itojun { 97 1.2 itojun register u_int16_t *w; 98 1.2 itojun register int sum = 0; 99 1.2 itojun register int mlen = 0; 100 1.2 itojun int byte_swapped = 0; 101 1.2 itojun struct ipovly ipov; 102 1.2 itojun 103 1.2 itojun union { 104 1.2 itojun u_int8_t c[2]; 105 1.2 itojun u_int16_t s; 106 1.2 itojun } s_util; 107 1.2 itojun union { 108 1.2 itojun u_int16_t s[2]; 109 1.2 itojun u_int32_t l; 110 1.2 itojun } l_util; 111 1.2 itojun 112 1.2 itojun /* pseudo header */ 113 1.2 itojun if (off < sizeof(struct ipovly)) 114 1.2 itojun panic("offset too short"); 115 1.2 itojun bzero(&ipov, sizeof(ipov)); 116 1.2 itojun ipov.ih_len = htons(len); 117 1.2 itojun ipov.ih_pr = nxt; 118 1.2 itojun ipov.ih_src = mtod(m, struct ip *)->ip_src; 119 1.2 itojun ipov.ih_dst = mtod(m, struct ip *)->ip_dst; 120 1.2 itojun w = (u_int16_t *)&ipov; 121 1.2 itojun /* assumes sizeof(ipov) == 20 */ 122 1.2 itojun sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; sum += w[4]; 123 1.2 itojun sum += w[5]; sum += w[6]; sum += w[7]; sum += w[8]; sum += w[9]; 124 1.2 itojun 125 1.2 itojun /* skip unnecessary part */ 126 1.2 itojun while (m && off > 0) { 127 1.2 itojun if (m->m_len > off) 128 1.2 itojun break; 129 1.2 itojun off -= m->m_len; 130 1.2 itojun m = m->m_next; 131 1.2 itojun } 132 1.2 itojun 133 1.2 itojun for (;m && len; m = m->m_next) { 134 1.2 itojun if (m->m_len == 0) 135 1.2 itojun continue; 136 1.2 itojun w = (u_int16_t *)(mtod(m, caddr_t) + off); 137 1.2 itojun if (mlen == -1) { 138 1.2 itojun /* 139 1.2 itojun * The first byte of this mbuf is the continuation 140 1.2 itojun * of a word spanning between this mbuf and the 141 1.2 itojun * last mbuf. 142 1.2 itojun * 143 1.2 itojun * s_util.c[0] is already saved when scanning previous 144 1.2 itojun * mbuf. 145 1.2 itojun */ 146 1.2 itojun s_util.c[1] = *(u_int8_t *)w; 147 1.2 itojun sum += s_util.s; 148 1.2 itojun w = (u_int16_t *)((u_int8_t *)w + 1); 149 1.2 itojun mlen = m->m_len - off - 1; 150 1.2 itojun len--; 151 1.2 itojun } else 152 1.2 itojun mlen = m->m_len - off; 153 1.2 itojun off = 0; 154 1.2 itojun if (len < mlen) 155 1.2 itojun mlen = len; 156 1.2 itojun len -= mlen; 157 1.2 itojun /* 158 1.2 itojun * Force to even boundary. 159 1.2 itojun */ 160 1.2 itojun if ((1 & (long) w) && (mlen > 0)) { 161 1.2 itojun REDUCE; 162 1.2 itojun sum <<= 8; 163 1.2 itojun s_util.c[0] = *(u_int8_t *)w; 164 1.2 itojun w = (u_int16_t *)((int8_t *)w + 1); 165 1.2 itojun mlen--; 166 1.2 itojun byte_swapped = 1; 167 1.2 itojun } 168 1.2 itojun /* 169 1.2 itojun * Unroll the loop to make overhead from 170 1.2 itojun * branches &c small. 171 1.2 itojun */ 172 1.2 itojun while ((mlen -= 32) >= 0) { 173 1.2 itojun sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 174 1.2 itojun sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 175 1.2 itojun sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 176 1.2 itojun sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 177 1.2 itojun w += 16; 178 1.2 itojun } 179 1.2 itojun mlen += 32; 180 1.2 itojun while ((mlen -= 8) >= 0) { 181 1.2 itojun sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 182 1.2 itojun w += 4; 183 1.2 itojun } 184 1.2 itojun mlen += 8; 185 1.2 itojun if (mlen == 0 && byte_swapped == 0) 186 1.2 itojun continue; 187 1.2 itojun REDUCE; 188 1.2 itojun while ((mlen -= 2) >= 0) { 189 1.2 itojun sum += *w++; 190 1.2 itojun } 191 1.2 itojun if (byte_swapped) { 192 1.2 itojun REDUCE; 193 1.2 itojun sum <<= 8; 194 1.2 itojun byte_swapped = 0; 195 1.2 itojun if (mlen == -1) { 196 1.2 itojun s_util.c[1] = *(u_int8_t *)w; 197 1.2 itojun sum += s_util.s; 198 1.2 itojun mlen = 0; 199 1.2 itojun } else 200 1.2 itojun mlen = -1; 201 1.2 itojun } else if (mlen == -1) 202 1.2 itojun s_util.c[0] = *(u_int8_t *)w; 203 1.2 itojun } 204 1.2 itojun if (len) 205 1.2 itojun printf("cksum4: out of data\n"); 206 1.2 itojun if (mlen == -1) { 207 1.2 itojun /* The last mbuf has odd # of bytes. Follow the 208 1.2 itojun standard (the odd byte may be shifted left by 8 bits 209 1.2 itojun or not as determined by endian-ness of the machine) */ 210 1.2 itojun s_util.c[1] = 0; 211 1.2 itojun sum += s_util.s; 212 1.2 itojun } 213 1.2 itojun REDUCE; 214 1.2 itojun return (~sum & 0xffff); 215 1.2 itojun } 216
Indexes created Thu Oct 02 01:09:59 GMT 2025