in6_cksum.c revision 1.18
1 /* $NetBSD: in6_cksum.c,v 1.18 2006/01/21 00:15:36 rpaulo 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 1.18 2006/01/21 00:15:36 rpaulo 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 #include <netinet6/scope6_var.h> 73 74 #include <net/net_osdep.h> 75 76 /* 77 * Checksum routine for Internet Protocol family headers (Portable Version). 78 * 79 * This routine is very heavily used in the network 80 * code and should be modified for each CPU to be as fast as possible. 81 */ 82 83 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) 84 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} 85 86 /* 87 * m MUST contain a continuous IP6 header. 88 * off is a offset where TCP/UDP/ICMP6 header starts. 89 * len is a total length of a transport segment. 90 * (e.g. TCP header + TCP payload) 91 */ 92 93 int 94 in6_cksum(m, nxt, off, len) 95 struct mbuf *m; 96 u_int8_t nxt; 97 u_int32_t off, len; 98 { 99 u_int16_t *w; 100 int sum = 0; 101 int mlen = 0; 102 int byte_swapped = 0; 103 struct ip6_hdr *ip6; 104 struct in6_addr in6; 105 union { 106 u_int16_t phs[4]; 107 struct { 108 u_int32_t ph_len; 109 u_int8_t ph_zero[3]; 110 u_int8_t ph_nxt; 111 } ph __attribute__((__packed__)); 112 } uph; 113 union { 114 u_int8_t c[2]; 115 u_int16_t s; 116 } s_util; 117 union { 118 u_int16_t s[2]; 119 u_int32_t l; 120 } l_util; 121 122 /* sanity check */ 123 if (m->m_pkthdr.len < off + len) { 124 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)", 125 m->m_pkthdr.len, off, len); 126 } 127 128 /* Skip pseudo-header if nxt == 0. */ 129 if (nxt == 0) 130 goto skip_phdr; 131 132 bzero(&uph, sizeof(uph)); 133 134 /* 135 * First create IP6 pseudo header and calculate a summary. 136 */ 137 ip6 = mtod(m, struct ip6_hdr *); 138 w = (u_int16_t *)&ip6->ip6_src; 139 uph.ph.ph_len = htonl(len); 140 uph.ph.ph_nxt = nxt; 141 142 /* 143 * IPv6 source address 144 * XXX: we'd like to avoid copying the address, but we can't due to 145 * the possibly embedded scope zone ID. 146 */ 147 in6 = ip6->ip6_src; 148 in6_clearscope(&in6); 149 w = (u_int16_t *)&in6; 150 sum += w[0]; 151 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 152 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 153 154 /* IPv6 destination address */ 155 in6 = ip6->ip6_dst; 156 in6_clearscope(&in6); 157 w = (u_int16_t *)&in6; 158 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 159 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 160 161 /* Payload length and upper layer identifier */ 162 sum += uph.phs[0]; sum += uph.phs[1]; 163 sum += uph.phs[2]; sum += uph.phs[3]; 164 165 skip_phdr: 166 /* 167 * Secondly calculate a summary of the first mbuf excluding offset. 168 */ 169 while (m != NULL && off > 0) { 170 if (m->m_len <= off) 171 off -= m->m_len; 172 else 173 break; 174 m = m->m_next; 175 } 176 w = (u_int16_t *)(mtod(m, u_char *) + off); 177 mlen = m->m_len - off; 178 if (len < mlen) 179 mlen = len; 180 len -= mlen; 181 /* 182 * Force to even boundary. 183 */ 184 if ((1 & (long) w) && (mlen > 0)) { 185 REDUCE; 186 sum <<= 8; 187 s_util.c[0] = *(u_char *)w; 188 w = (u_int16_t *)((char *)w + 1); 189 mlen--; 190 byte_swapped = 1; 191 } 192 /* 193 * Unroll the loop to make overhead from 194 * branches &c small. 195 */ 196 while ((mlen -= 32) >= 0) { 197 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 198 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 199 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 200 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 201 w += 16; 202 } 203 mlen += 32; 204 while ((mlen -= 8) >= 0) { 205 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 206 w += 4; 207 } 208 mlen += 8; 209 if (mlen == 0 && byte_swapped == 0) 210 goto next; 211 REDUCE; 212 while ((mlen -= 2) >= 0) { 213 sum += *w++; 214 } 215 if (byte_swapped) { 216 REDUCE; 217 sum <<= 8; 218 byte_swapped = 0; 219 if (mlen == -1) { 220 s_util.c[1] = *(char *)w; 221 sum += s_util.s; 222 mlen = 0; 223 } else 224 mlen = -1; 225 } else if (mlen == -1) 226 s_util.c[0] = *(char *)w; 227 next: 228 m = m->m_next; 229 230 /* 231 * Lastly calculate a summary of the rest of mbufs. 232 */ 233 234 for (;m && len; m = m->m_next) { 235 if (m->m_len == 0) 236 continue; 237 w = mtod(m, u_int16_t *); 238 if (mlen == -1) { 239 /* 240 * The first byte of this mbuf is the continuation 241 * of a word spanning between this mbuf and the 242 * last mbuf. 243 * 244 * s_util.c[0] is already saved when scanning previous 245 * mbuf. 246 */ 247 s_util.c[1] = *(char *)w; 248 sum += s_util.s; 249 w = (u_int16_t *)((char *)w + 1); 250 mlen = m->m_len - 1; 251 len--; 252 } else 253 mlen = m->m_len; 254 if (len < mlen) 255 mlen = len; 256 len -= mlen; 257 /* 258 * Force to even boundary. 259 */ 260 if ((1 & (long) w) && (mlen > 0)) { 261 REDUCE; 262 sum <<= 8; 263 s_util.c[0] = *(u_char *)w; 264 w = (u_int16_t *)((char *)w + 1); 265 mlen--; 266 byte_swapped = 1; 267 } 268 /* 269 * Unroll the loop to make overhead from 270 * branches &c small. 271 */ 272 while ((mlen -= 32) >= 0) { 273 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 274 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 275 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 276 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 277 w += 16; 278 } 279 mlen += 32; 280 while ((mlen -= 8) >= 0) { 281 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 282 w += 4; 283 } 284 mlen += 8; 285 if (mlen == 0 && byte_swapped == 0) 286 continue; 287 REDUCE; 288 while ((mlen -= 2) >= 0) { 289 sum += *w++; 290 } 291 if (byte_swapped) { 292 REDUCE; 293 sum <<= 8; 294 byte_swapped = 0; 295 if (mlen == -1) { 296 s_util.c[1] = *(char *)w; 297 sum += s_util.s; 298 mlen = 0; 299 } else 300 mlen = -1; 301 } else if (mlen == -1) 302 s_util.c[0] = *(char *)w; 303 } 304 if (len) 305 panic("in6_cksum: out of data"); 306 if (mlen == -1) { 307 /* The last mbuf has odd # of bytes. Follow the 308 standard (the odd byte may be shifted left by 8 bits 309 or not as determined by endian-ness of the machine) */ 310 s_util.c[1] = 0; 311 sum += s_util.s; 312 } 313 REDUCE; 314 return (~sum & 0xffff); 315 } 316
Indexes created Wed Oct 01 19:09:53 GMT 2025