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(struct mbuf *m, u_int8_t nxt, u_int32_t off, u_int32_t len) 92 { 93 u_int16_t *w; 94 int sum = 0; 95 int mlen = 0; 96 int byte_swapped = 0; 97 struct ip6_hdr *ip6; 98 struct in6_addr in6; 99 union { 100 u_int16_t phs[4]; 101 struct { 102 u_int32_t ph_len; 103 u_int8_t ph_zero[3]; 104 u_int8_t ph_nxt; 105 } ph __packed; 106 } uph; 107 union { 108 u_int8_t c[2]; 109 u_int16_t s; 110 } s_util; 111 union { 112 u_int16_t s[2]; 113 u_int32_t l; 114 } l_util; 115 116 /* sanity check */ 117 if (m->m_pkthdr.len < off + len) { 118 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)", 119 m->m_pkthdr.len, off, len); 120 } 121 122 bzero(&uph, sizeof(uph)); 123 124 /* 125 * First create IP6 pseudo header and calculate a summary. 126 */ 127 ip6 = mtod(m, struct ip6_hdr *); 128 uph.ph.ph_len = htonl(len); 129 uph.ph.ph_nxt = nxt; 130 131 /* 132 * IPv6 source address. 133 * XXX: we'd like to avoid copying the address, but we can't due to 134 * the possibly embedded scope zone ID. 135 */ 136 in6 = ip6->ip6_src; 137 in6_clearscope(&in6); 138 w = (u_int16_t *)&in6; 139 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 140 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 141 142 /* IPv6 destination address */ 143 in6 = ip6->ip6_dst; 144 in6_clearscope(&in6); 145 w = (u_int16_t *)&in6; 146 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 147 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 148 149 /* Payload length and upper layer identifier */ 150 sum += uph.phs[0]; sum += uph.phs[1]; 151 sum += uph.phs[2]; sum += uph.phs[3]; 152 153 /* 154 * Secondly calculate a summary of the first mbuf excluding offset. 155 */ 156 while (m != NULL && off > 0) { 157 if (m->m_len <= off) 158 off -= m->m_len; 159 else 160 break; 161 m = m->m_next; 162 } 163 w = (u_int16_t *)(mtod(m, u_char *) + off); 164 mlen = m->m_len - off; 165 if (len < mlen) 166 mlen = len; 167 len -= mlen; 168 /* 169 * Force to even boundary. 170 */ 171 if ((1 & (long) w) && (mlen > 0)) { 172 REDUCE; 173 sum <<= 8; 174 s_util.c[0] = *(u_char *)w; 175 w = (u_int16_t *)((char *)w + 1); 176 mlen--; 177 byte_swapped = 1; 178 } 179 /* 180 * Unroll the loop to make overhead from 181 * branches &c small. 182 */ 183 while ((mlen -= 32) >= 0) { 184 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 185 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 186 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 187 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 188 w += 16; 189 } 190 mlen += 32; 191 while ((mlen -= 8) >= 0) { 192 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 193 w += 4; 194 } 195 mlen += 8; 196 if (mlen == 0 && byte_swapped == 0) 197 goto next; 198 REDUCE; 199 while ((mlen -= 2) >= 0) { 200 sum += *w++; 201 } 202 if (byte_swapped) { 203 REDUCE; 204 sum <<= 8; 205 byte_swapped = 0; 206 if (mlen == -1) { 207 s_util.c[1] = *(char *)w; 208 sum += s_util.s; 209 mlen = 0; 210 } else 211 mlen = -1; 212 } else if (mlen == -1) 213 s_util.c[0] = *(char *)w; 214 next: 215 m = m->m_next; 216 217 /* 218 * Lastly calculate a summary of the rest of mbufs. 219 */ 220 221 for (;m && len; m = m->m_next) { 222 if (m->m_len == 0) 223 continue; 224 w = mtod(m, u_int16_t *); 225 if (mlen == -1) { 226 /* 227 * The first byte of this mbuf is the continuation 228 * of a word spanning between this mbuf and the 229 * last mbuf. 230 * 231 * s_util.c[0] is already saved when scanning previous 232 * mbuf. 233 */ 234 s_util.c[1] = *(char *)w; 235 sum += s_util.s; 236 w = (u_int16_t *)((char *)w + 1); 237 mlen = m->m_len - 1; 238 len--; 239 } else 240 mlen = m->m_len; 241 if (len < mlen) 242 mlen = len; 243 len -= mlen; 244 /* 245 * Force to even boundary. 246 */ 247 if ((1 & (long) w) && (mlen > 0)) { 248 REDUCE; 249 sum <<= 8; 250 s_util.c[0] = *(u_char *)w; 251 w = (u_int16_t *)((char *)w + 1); 252 mlen--; 253 byte_swapped = 1; 254 } 255 /* 256 * Unroll the loop to make overhead from 257 * branches &c small. 258 */ 259 while ((mlen -= 32) >= 0) { 260 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 261 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; 262 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; 263 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; 264 w += 16; 265 } 266 mlen += 32; 267 while ((mlen -= 8) >= 0) { 268 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; 269 w += 4; 270 } 271 mlen += 8; 272 if (mlen == 0 && byte_swapped == 0) 273 continue; 274 REDUCE; 275 while ((mlen -= 2) >= 0) { 276 sum += *w++; 277 } 278 if (byte_swapped) { 279 REDUCE; 280 sum <<= 8; 281 byte_swapped = 0; 282 if (mlen == -1) { 283 s_util.c[1] = *(char *)w; 284 sum += s_util.s; 285 mlen = 0; 286 } else 287 mlen = -1; 288 } else if (mlen == -1) 289 s_util.c[0] = *(char *)w; 290 } 291 if (len) 292 panic("in6_cksum: out of data"); 293 if (mlen == -1) { 294 /* The last mbuf has odd # of bytes. Follow the 295 standard (the odd byte may be shifted left by 8 bits 296 or not as determined by endian-ness of the machine) */ 297 s_util.c[1] = 0; 298 sum += s_util.s; 299 } 300 REDUCE; 301 return (~sum & 0xffff); 302 } 303