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 #include <net/net_osdep.h> 72 73 /* 74 * Checksum routine for Internet Protocol family headers (Portable Version). 75 * 76 * This routine is very heavily used in the network 77 * code and should be modified for each CPU to be as fast as possible. 78 */ 79 80 #define ADDCARRY(x) (x > 65535 ? x -= 65535 : x) 81 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);} 82 83 /* 84 * m MUST contain a continuous IP6 header. 85 * off is an offset where TCP/UDP/ICMP6 header starts. 86 * len is a total length of a transport segment. 87 * (e.g. TCP header + TCP payload) 88 */ 89 90 int 91 in6_cksum(m, nxt, off, len) 92 struct mbuf *m; 93 u_int8_t nxt; 94 u_int32_t off, len; 95 { 96 u_int16_t *w; 97 int sum = 0; 98 int mlen = 0; 99 int byte_swapped = 0; 100 struct ip6_hdr *ip6; 101 struct in6_addr in6; 102 union { 103 u_int16_t phs[4]; 104 struct { 105 u_int32_t ph_len; 106 u_int8_t ph_zero[3]; 107 u_int8_t ph_nxt; 108 } ph __packed; 109 } uph; 110 union { 111 u_int8_t c[2]; 112 u_int16_t s; 113 } s_util; 114 union { 115 u_int16_t s[2]; 116 u_int32_t l; 117 } l_util; 118 119 /* sanity check */ 120 if (m->m_pkthdr.len < off + len) { 121 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)", 122 m->m_pkthdr.len, off, len); 123 } 124 125 bzero(&uph, sizeof(uph)); 126 127 /* 128 * First create IP6 pseudo header and calculate a summary. 129 */ 130 ip6 = mtod(m, struct ip6_hdr *); 131 uph.ph.ph_len = htonl(len); 132 uph.ph.ph_nxt = nxt; 133 134 /* 135 * IPv6 source address. 136 * XXX: we'd like to avoid copying the address, but we can't due to 137 * the possibly embedded scope zone ID. 138 */ 139 in6 = ip6->ip6_src; 140 in6_clearscope(&in6); 141 w = (u_int16_t *)&in6; 142 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 143 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 144 145 /* IPv6 destination address */ 146 in6 = ip6->ip6_dst; 147 in6_clearscope(&in6); 148 w = (u_int16_t *)&in6; 149 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 150 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 151 152 /* 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 /* 157 * Secondly calculate a summary of the first mbuf excluding offset. 158 */ 159 while (m != NULL && off > 0) { 160 if (m->m_len <= off) 161 off -= m->m_len; 162 else 163 break; 164 m = m->m_next; 165 } 166 w = (u_int16_t *)(mtod(m, u_char *) + off); 167 mlen = m->m_len - off; 168 if (len < mlen) 169 mlen = len; 170 len -= mlen; 171 /* 172 * Force to even boundary. 173 */ 174 if ((1 & (long) w) && (mlen > 0)) { 175 REDUCE; 176 sum <<= 8; 177 s_util.c[0] = *(u_char *)w; 178 w = (u_int16_t *)((char *)w + 1); 179 mlen--; 180 byte_swapped = 1; 181 } 182 /* 183 * Unroll the loop to make overhead from 184 * branches &c small. 185 */ 186 while ((mlen -= 32) >= 0) { 187 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 188 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 189 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 190 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 191 w += 16; 192 } 193 mlen += 32; 194 while ((mlen -= 8) >= 0) { 195 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 196 w += 4; 197 } 198 mlen += 8; 199 if (mlen == 0 && byte_swapped == 0) 200 goto next; 201 REDUCE; 202 while ((mlen -= 2) >= 0) { 203 sum += *w++; 204 } 205 if (byte_swapped) { 206 REDUCE; 207 sum <<= 8; 208 byte_swapped = 0; 209 if (mlen == -1) { 210 s_util.c[1] = *(char *)w; 211 sum += s_util.s; 212 mlen = 0; 213 } else 214 mlen = -1; 215 } else if (mlen == -1) 216 s_util.c[0] = *(char *)w; 217 next: 218 m = m->m_next; 219 220 /* 221 * Lastly calculate a summary of the rest of mbufs. 222 */ 223 224 for (;m && len; m = m->m_next) { 225 if (m->m_len == 0) 226 continue; 227 w = mtod(m, u_int16_t *); 228 if (mlen == -1) { 229 /* 230 * The first byte of this mbuf is the continuation 231 * of a word spanning between this mbuf and the 232 * last mbuf. 233 * 234 * s_util.c[0] is already saved when scanning previous 235 * mbuf. 236 */ 237 s_util.c[1] = *(char *)w; 238 sum += s_util.s; 239 w = (u_int16_t *)((char *)w + 1); 240 mlen = m->m_len - 1; 241 len--; 242 } else 243 mlen = m->m_len; 244 if (len < mlen) 245 mlen = len; 246 len -= mlen; 247 /* 248 * Force to even boundary. 249 */ 250 if ((1 & (long) w) && (mlen > 0)) { 251 REDUCE; 252 sum <<= 8; 253 s_util.c[0] = *(u_char *)w; 254 w = (u_int16_t *)((char *)w + 1); 255 mlen--; 256 byte_swapped = 1; 257 } 258 /* 259 * Unroll the loop to make overhead from 260 * branches &c small. 261 */ 262 while ((mlen -= 32) >= 0) { 263 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 264 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 265 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 266 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 267 w += 16; 268 } 269 mlen += 32; 270 while ((mlen -= 8) >= 0) { 271 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 272 w += 4; 273 } 274 mlen += 8; 275 if (mlen == 0 && byte_swapped == 0) 276 continue; 277 REDUCE; 278 while ((mlen -= 2) >= 0) { 279 sum += *w++; 280 } 281 if (byte_swapped) { 282 REDUCE; 283 sum <<= 8; 284 byte_swapped = 0; 285 if (mlen == -1) { 286 s_util.c[1] = *(char *)w; 287 sum += s_util.s; 288 mlen = 0; 289 } else 290 mlen = -1; 291 } else if (mlen == -1) 292 s_util.c[0] = *(char *)w; 293 } 294 if (len) 295 panic("in6_cksum: out of data"); 296 if (mlen == -1) { 297 /* The last mbuf has odd # of bytes. Follow the 298 standard (the odd byte may be shifted left by 8 bits 299 or not as determined by endian-ness of the machine) */ 300 s_util.c[1] = 0; 301 sum += s_util.s; 302 } 303 REDUCE; 304 return (~sum & 0xffff); 305 } 306