in6_cksum.c revision 1.16
1 /* $NetBSD: in6_cksum.c,v 1.16 2003/08/07 16:33:24 agc Exp $ */ 2 /* $KAME: in6_cksum.c,v 1.9 2000/09/09 15:33:31 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 * 3. 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/cdefs.h> 65 __KERNEL_RCSID(0, "$NetBSD: in6_cksum.c,v 1.16 2003/08/07 16:33:24 agc Exp $"); 66 67 #include <sys/param.h> 68 #include <sys/mbuf.h> 69 #include <sys/systm.h> 70 #include <netinet/in.h> 71 #include <netinet/ip6.h> 72 73 #include <net/net_osdep.h> 74 75 /* 76 * Checksum routine for Internet Protocol family headers (Portable Version). 77 * 78 * This routine is very heavily used in the network 79 * code and should be modified for each CPU to be as fast as possible. 80 */ 81 82 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) 83 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} 84 85 /* 86 * m MUST contain a continuous IP6 header. 87 * off is a offset where TCP/UDP/ICMP6 header starts. 88 * len is a total length of a transport segment. 89 * (e.g. TCP header + TCP payload) 90 */ 91 92 int 93 in6_cksum(m, nxt, off, len) 94 struct mbuf *m; 95 u_int8_t nxt; 96 u_int32_t off, len; 97 { 98 u_int16_t *w; 99 int sum = 0; 100 int mlen = 0; 101 int byte_swapped = 0; 102 struct ip6_hdr *ip6; 103 union { 104 u_int16_t phs[4]; 105 struct { 106 u_int32_t ph_len; 107 u_int8_t ph_zero[3]; 108 u_int8_t ph_nxt; 109 } ph __attribute__((__packed__)); 110 } uph; 111 union { 112 u_int8_t c[2]; 113 u_int16_t s; 114 } s_util; 115 union { 116 u_int16_t s[2]; 117 u_int32_t l; 118 } l_util; 119 120 /* sanity check */ 121 if (m->m_pkthdr.len < off + len) { 122 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)", 123 m->m_pkthdr.len, off, len); 124 } 125 126 /* Skip pseudo-header if nxt == 0. */ 127 if (nxt == 0) 128 goto skip_phdr; 129 130 bzero(&uph, sizeof(uph)); 131 132 /* 133 * First create IP6 pseudo header and calculate a summary. 134 */ 135 ip6 = mtod(m, struct ip6_hdr *); 136 w = (u_int16_t *)&ip6->ip6_src; 137 uph.ph.ph_len = htonl(len); 138 uph.ph.ph_nxt = nxt; 139 140 /* IPv6 source address */ 141 sum += w[0]; 142 if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) 143 sum += w[1]; 144 sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5]; 145 sum += w[6]; sum += w[7]; 146 /* IPv6 destination address */ 147 sum += w[8]; 148 if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) 149 sum += w[9]; 150 sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13]; 151 sum += w[14]; sum += w[15]; 152 /* Payload length and upper layer identifier */ 153 sum += uph.phs[0]; sum += uph.phs[1]; 154 sum += uph.phs[2]; sum += uph.phs[3]; 155 156 skip_phdr: 157 /* 158 * Secondly calculate a summary of the first mbuf excluding offset. 159 */ 160 while (m != NULL && off > 0) { 161 if (m->m_len <= off) 162 off -= m->m_len; 163 else 164 break; 165 m = m->m_next; 166 } 167 w = (u_int16_t *)(mtod(m, u_char *) + off); 168 mlen = m->m_len - off; 169 if (len < mlen) 170 mlen = len; 171 len -= mlen; 172 /* 173 * Force to even boundary. 174 */ 175 if ((1 & (long) w) && (mlen > 0)) { 176 REDUCE; 177 sum <<= 8; 178 s_util.c[0] = *(u_char *)w; 179 w = (u_int16_t *)((char *)w + 1); 180 mlen--; 181 byte_swapped = 1; 182 } 183 /* 184 * Unroll the loop to make overhead from 185 * branches &c small. 186 */ 187 while ((mlen -= 32) >= 0) { 188 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 189 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 190 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 191 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 192 w += 16; 193 } 194 mlen += 32; 195 while ((mlen -= 8) >= 0) { 196 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 197 w += 4; 198 } 199 mlen += 8; 200 if (mlen == 0 && byte_swapped == 0) 201 goto next; 202 REDUCE; 203 while ((mlen -= 2) >= 0) { 204 sum += *w++; 205 } 206 if (byte_swapped) { 207 REDUCE; 208 sum <<= 8; 209 byte_swapped = 0; 210 if (mlen == -1) { 211 s_util.c[1] = *(char *)w; 212 sum += s_util.s; 213 mlen = 0; 214 } else 215 mlen = -1; 216 } else if (mlen == -1) 217 s_util.c[0] = *(char *)w; 218 next: 219 m = m->m_next; 220 221 /* 222 * Lastly calculate a summary of the rest of mbufs. 223 */ 224 225 for (;m && len; m = m->m_next) { 226 if (m->m_len == 0) 227 continue; 228 w = mtod(m, u_int16_t *); 229 if (mlen == -1) { 230 /* 231 * The first byte of this mbuf is the continuation 232 * of a word spanning between this mbuf and the 233 * last mbuf. 234 * 235 * s_util.c[0] is already saved when scanning previous 236 * mbuf. 237 */ 238 s_util.c[1] = *(char *)w; 239 sum += s_util.s; 240 w = (u_int16_t *)((char *)w + 1); 241 mlen = m->m_len - 1; 242 len--; 243 } else 244 mlen = m->m_len; 245 if (len < mlen) 246 mlen = len; 247 len -= mlen; 248 /* 249 * Force to even boundary. 250 */ 251 if ((1 & (long) w) && (mlen > 0)) { 252 REDUCE; 253 sum <<= 8; 254 s_util.c[0] = *(u_char *)w; 255 w = (u_int16_t *)((char *)w + 1); 256 mlen--; 257 byte_swapped = 1; 258 } 259 /* 260 * Unroll the loop to make overhead from 261 * branches &c small. 262 */ 263 while ((mlen -= 32) >= 0) { 264 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 265 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 266 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 267 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 268 w += 16; 269 } 270 mlen += 32; 271 while ((mlen -= 8) >= 0) { 272 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 273 w += 4; 274 } 275 mlen += 8; 276 if (mlen == 0 && byte_swapped == 0) 277 continue; 278 REDUCE; 279 while ((mlen -= 2) >= 0) { 280 sum += *w++; 281 } 282 if (byte_swapped) { 283 REDUCE; 284 sum <<= 8; 285 byte_swapped = 0; 286 if (mlen == -1) { 287 s_util.c[1] = *(char *)w; 288 sum += s_util.s; 289 mlen = 0; 290 } else 291 mlen = -1; 292 } else if (mlen == -1) 293 s_util.c[0] = *(char *)w; 294 } 295 if (len) 296 panic("in6_cksum: out of data"); 297 if (mlen == -1) { 298 /* The last mbuf has odd # of bytes. Follow the 299 standard (the odd byte may be shifted left by 8 bits 300 or not as determined by endian-ness of the machine) */ 301 s_util.c[1] = 0; 302 sum += s_util.s; 303 } 304 REDUCE; 305 return (~sum & 0xffff); 306 } 307
Indexes created Wed Oct 01 19:09:53 GMT 2025