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