in6_cksum.c revision 139826
1/* $FreeBSD: head/sys/netinet6/in6_cksum.c 139826 2005-01-07 02:30:35Z imp $ */ 2/* $KAME: in6_cksum.c,v 1.10 2000/12/03 00:53:59 itojun Exp $ */ 3 4/*- 5 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the project nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33/*- 34 * Copyright (c) 1988, 1992, 1993 35 * The Regents of the University of California. All rights reserved. 36 * 37 * Redistribution and use in source and binary forms, with or without 38 * modification, are permitted provided that the following conditions 39 * are met: 40 * 1. Redistributions of source code must retain the above copyright 41 * notice, this list of conditions and the following disclaimer. 42 * 2. Redistributions in binary form must reproduce the above copyright 43 * notice, this list of conditions and the following disclaimer in the 44 * documentation and/or other materials provided with the distribution. 45 * 4. Neither the name of the University nor the names of its contributors 46 * may be used to endorse or promote products derived from this software 47 * without specific prior written permission. 48 * 49 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 50 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 51 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 52 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 53 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 54 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 55 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 56 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 57 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 58 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 59 * SUCH DAMAGE. 60 * 61 * @(#)in_cksum.c 8.1 (Berkeley) 6/10/93 62 */ 63 64#include <sys/param.h> 65#include <sys/mbuf.h> 66#include <sys/systm.h> 67#include <netinet/in.h> 68#include <netinet/ip6.h> 69 70#include <net/net_osdep.h> 71 72/* 73 * Checksum routine for Internet Protocol family headers (Portable Version). 74 * 75 * This routine is very heavily used in the network 76 * code and should be modified for each CPU to be as fast as possible. 77 */ 78 79#define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) 80#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} 81 82/* 83 * m MUST contain a continuous IP6 header. 84 * off is an offset where TCP/UDP/ICMP6 header starts. 85 * len is a total length of a transport segment. 86 * (e.g. TCP header + TCP payload) 87 */ 88 89int 90in6_cksum(m, nxt, off, len) 91 struct mbuf *m; 92 u_int8_t nxt; 93 u_int32_t off, len; 94{ 95 u_int16_t *w; 96 int sum = 0; 97 int mlen = 0; 98 int byte_swapped = 0; 99 struct ip6_hdr *ip6; 100 union { 101 u_int16_t phs[4]; 102 struct { 103 u_int32_t ph_len; 104 u_int8_t ph_zero[3]; 105 u_int8_t ph_nxt; 106 } ph __packed; 107 } uph; 108 union { 109 u_int8_t c[2]; 110 u_int16_t s; 111 } s_util; 112 union { 113 u_int16_t s[2]; 114 u_int32_t l; 115 } l_util; 116 117 /* sanity check */ 118 if (m->m_pkthdr.len < off + len) { 119 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)", 120 m->m_pkthdr.len, off, len); 121 } 122 123 bzero(&uph, sizeof(uph)); 124 125 /* 126 * First create IP6 pseudo header and calculate a summary. 127 */ 128 ip6 = mtod(m, struct ip6_hdr *); 129 w = (u_int16_t *)&ip6->ip6_src; 130 uph.ph.ph_len = htonl(len); 131 uph.ph.ph_nxt = nxt; 132 133 /* IPv6 source address */ 134 sum += w[0]; 135 if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) 136 sum += w[1]; 137 sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5]; 138 sum += w[6]; sum += w[7]; 139 /* IPv6 destination address */ 140 sum += w[8]; 141 if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) 142 sum += w[9]; 143 sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13]; 144 sum += w[14]; sum += w[15]; 145 /* Payload length and upper layer identifier */ 146 sum += uph.phs[0]; sum += uph.phs[1]; 147 sum += uph.phs[2]; sum += uph.phs[3]; 148 149 /* 150 * Secondly calculate a summary of the first mbuf excluding offset. 151 */ 152 while (m != NULL && off > 0) { 153 if (m->m_len <= off) 154 off -= m->m_len; 155 else 156 break; 157 m = m->m_next; 158 } 159 w = (u_int16_t *)(mtod(m, u_char *) + off); 160 mlen = m->m_len - off; 161 if (len < mlen) 162 mlen = len; 163 len -= mlen; 164 /* 165 * Force to even boundary. 166 */ 167 if ((1 & (long) w) && (mlen > 0)) { 168 REDUCE; 169 sum <<= 8; 170 s_util.c[0] = *(u_char *)w; 171 w = (u_int16_t *)((char *)w + 1); 172 mlen--; 173 byte_swapped = 1; 174 } 175 /* 176 * Unroll the loop to make overhead from 177 * branches &c small. 178 */ 179 while ((mlen -= 32) >= 0) { 180 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 181 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 182 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 183 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 184 w += 16; 185 } 186 mlen += 32; 187 while ((mlen -= 8) >= 0) { 188 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 189 w += 4; 190 } 191 mlen += 8; 192 if (mlen == 0 && byte_swapped == 0) 193 goto next; 194 REDUCE; 195 while ((mlen -= 2) >= 0) { 196 sum += *w++; 197 } 198 if (byte_swapped) { 199 REDUCE; 200 sum <<= 8; 201 byte_swapped = 0; 202 if (mlen == -1) { 203 s_util.c[1] = *(char *)w; 204 sum += s_util.s; 205 mlen = 0; 206 } else 207 mlen = -1; 208 } else if (mlen == -1) 209 s_util.c[0] = *(char *)w; 210 next: 211 m = m->m_next; 212 213 /* 214 * Lastly calculate a summary of the rest of mbufs. 215 */ 216 217 for (;m && len; m = m->m_next) { 218 if (m->m_len == 0) 219 continue; 220 w = mtod(m, u_int16_t *); 221 if (mlen == -1) { 222 /* 223 * The first byte of this mbuf is the continuation 224 * of a word spanning between this mbuf and the 225 * last mbuf. 226 * 227 * s_util.c[0] is already saved when scanning previous 228 * mbuf. 229 */ 230 s_util.c[1] = *(char *)w; 231 sum += s_util.s; 232 w = (u_int16_t *)((char *)w + 1); 233 mlen = m->m_len - 1; 234 len--; 235 } else 236 mlen = m->m_len; 237 if (len < mlen) 238 mlen = len; 239 len -= mlen; 240 /* 241 * Force to even boundary. 242 */ 243 if ((1 & (long) w) && (mlen > 0)) { 244 REDUCE; 245 sum <<= 8; 246 s_util.c[0] = *(u_char *)w; 247 w = (u_int16_t *)((char *)w + 1); 248 mlen--; 249 byte_swapped = 1; 250 } 251 /* 252 * Unroll the loop to make overhead from 253 * branches &c small. 254 */ 255 while ((mlen -= 32) >= 0) { 256 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 257 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 258 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 259 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 260 w += 16; 261 } 262 mlen += 32; 263 while ((mlen -= 8) >= 0) { 264 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 265 w += 4; 266 } 267 mlen += 8; 268 if (mlen == 0 && byte_swapped == 0) 269 continue; 270 REDUCE; 271 while ((mlen -= 2) >= 0) { 272 sum += *w++; 273 } 274 if (byte_swapped) { 275 REDUCE; 276 sum <<= 8; 277 byte_swapped = 0; 278 if (mlen == -1) { 279 s_util.c[1] = *(char *)w; 280 sum += s_util.s; 281 mlen = 0; 282 } else 283 mlen = -1; 284 } else if (mlen == -1) 285 s_util.c[0] = *(char *)w; 286 } 287 if (len) 288 panic("in6_cksum: out of data"); 289 if (mlen == -1) { 290 /* The last mbuf has odd # of bytes. Follow the 291 standard (the odd byte may be shifted left by 8 bits 292 or not as determined by endian-ness of the machine) */ 293 s_util.c[1] = 0; 294 sum += s_util.s; 295 } 296 REDUCE; 297 return (~sum & 0xffff); 298} 299