1 /* $FreeBSD$ */ 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 #include <netinet6/scope6_var.h> 70 71 /* 72 * Checksum routine for Internet Protocol family headers (Portable Version). 73 * 74 * This routine is very heavily used in the network 75 * code and should be modified for each CPU to be as fast as possible. 76 */ 77 78 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) 79 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} 80 81 /* 82 * m MUST contain a continuous IP6 header. 83 * off is an offset where TCP/UDP/ICMP6 header starts. 84 * len is a total length of a transport segment. 85 * (e.g. TCP header + TCP payload) 86 */ 87 88 int 89 in6_cksum(struct mbuf *m, u_int8_t nxt, u_int32_t off, u_int32_t len) 90 { 91 u_int16_t *w; 92 int sum = 0; 93 int mlen = 0; 94 int byte_swapped = 0; 95 struct ip6_hdr *ip6; 96 struct in6_addr in6; 97 union { 98 u_int16_t phs[4]; 99 struct { 100 u_int32_t ph_len; 101 u_int8_t ph_zero[3]; 102 u_int8_t ph_nxt; 103 } __packed ph; 104 } uph; 105 union { 106 u_int8_t c[2]; 107 u_int16_t s; 108 } s_util; 109 union { 110 u_int16_t s[2]; 111 u_int32_t l; 112 } l_util; 113 114 /* sanity check */ 115 if (m->m_pkthdr.len < off + len) { 116 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)", 117 m->m_pkthdr.len, off, len); 118 } 119 120 bzero(&uph, sizeof(uph)); 121 122 /* 123 * First create IP6 pseudo header and calculate a summary. 124 */ 125 ip6 = mtod(m, struct ip6_hdr *); 126 uph.ph.ph_len = htonl(len); 127 uph.ph.ph_nxt = nxt; 128 129 /* 130 * IPv6 source address. 131 * XXX: we'd like to avoid copying the address, but we can't due to 132 * the possibly embedded scope zone ID. 133 */ 134 in6 = ip6->ip6_src; 135 in6_clearscope(&in6); 136 w = (u_int16_t *)&in6; 137 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 138 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 139 140 /* IPv6 destination address */ 141 in6 = ip6->ip6_dst; 142 in6_clearscope(&in6); 143 w = (u_int16_t *)&in6; 144 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 145 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 146 147 /* Payload length and upper layer identifier */ 148 sum += uph.phs[0]; sum += uph.phs[1]; 149 sum += uph.phs[2]; sum += uph.phs[3]; 150 151 /* 152 * Secondly calculate a summary of the first mbuf excluding offset. 153 */ 154 while (off > 0) { 155 if (m->m_len <= off) 156 off -= m->m_len; 157 else 158 break; 159 m = m->m_next; 160 } 161 w = (u_int16_t *)(mtod(m, u_char *) + off); 162 mlen = m->m_len - off; 163 if (len < mlen) 164 mlen = len; 165 len -= mlen; 166 /* 167 * Force to even boundary. 168 */ 169 if ((1 & (long) w) && (mlen > 0)) { 170 REDUCE; 171 sum <<= 8; 172 s_util.c[0] = *(u_char *)w; 173 w = (u_int16_t *)((char *)w + 1); 174 mlen--; 175 byte_swapped = 1; 176 } 177 /* 178 * Unroll the loop to make overhead from 179 * branches &c small. 180 */ 181 while ((mlen -= 32) >= 0) { 182 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 183 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 184 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 185 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 186 w += 16; 187 } 188 mlen += 32; 189 while ((mlen -= 8) >= 0) { 190 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 191 w += 4; 192 } 193 mlen += 8; 194 if (mlen == 0 && byte_swapped == 0) 195 goto next; 196 REDUCE; 197 while ((mlen -= 2) >= 0) { 198 sum += *w++; 199 } 200 if (byte_swapped) { 201 REDUCE; 202 sum <<= 8; 203 byte_swapped = 0; 204 if (mlen == -1) { 205 s_util.c[1] = *(char *)w; 206 sum += s_util.s; 207 mlen = 0; 208 } else 209 mlen = -1; 210 } else if (mlen == -1) 211 s_util.c[0] = *(char *)w; 212 next: 213 m = m->m_next; 214 215 /* 216 * Lastly calculate a summary of the rest of mbufs. 217 */ 218 219 for (;m && len; m = m->m_next) { 220 if (m->m_len == 0) 221 continue; 222 w = mtod(m, u_int16_t *); 223 if (mlen == -1) { 224 /* 225 * The first byte of this mbuf is the continuation 226 * of a word spanning between this mbuf and the 227 * last mbuf. 228 * 229 * s_util.c[0] is already saved when scanning previous 230 * mbuf. 231 */ 232 s_util.c[1] = *(char *)w; 233 sum += s_util.s; 234 w = (u_int16_t *)((char *)w + 1); 235 mlen = m->m_len - 1; 236 len--; 237 } else 238 mlen = m->m_len; 239 if (len < mlen) 240 mlen = len; 241 len -= mlen; 242 /* 243 * Force to even boundary. 244 */ 245 if ((1 & (long) w) && (mlen > 0)) { 246 REDUCE; 247 sum <<= 8; 248 s_util.c[0] = *(u_char *)w; 249 w = (u_int16_t *)((char *)w + 1); 250 mlen--; 251 byte_swapped = 1; 252 } 253 /* 254 * Unroll the loop to make overhead from 255 * branches &c small. 256 */ 257 while ((mlen -= 32) >= 0) { 258 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 259 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 260 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 261 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 262 w += 16; 263 } 264 mlen += 32; 265 while ((mlen -= 8) >= 0) { 266 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 267 w += 4; 268 } 269 mlen += 8; 270 if (mlen == 0 && byte_swapped == 0) 271 continue; 272 REDUCE; 273 while ((mlen -= 2) >= 0) { 274 sum += *w++; 275 } 276 if (byte_swapped) { 277 REDUCE; 278 sum <<= 8; 279 byte_swapped = 0; 280 if (mlen == -1) { 281 s_util.c[1] = *(char *)w; 282 sum += s_util.s; 283 mlen = 0; 284 } else 285 mlen = -1; 286 } else if (mlen == -1) 287 s_util.c[0] = *(char *)w; 288 } 289 if (len) 290 panic("in6_cksum: out of data"); 291 if (mlen == -1) { 292 /* The last mbuf has odd # of bytes. Follow the 293 standard (the odd byte may be shifted left by 8 bits 294 or not as determined by endian-ness of the machine) */ 295 s_util.c[1] = 0; 296 sum += s_util.s; 297 } 298 REDUCE; 299 return (~sum & 0xffff); 300 } 301