bsd/netinet6/in6_cksum.c

   1 /*      $FreeBSD: src/sys/netinet6/in6_cksum.c,v 1.1.2.3 2001/07/03 11:01:52 ume Exp $  */
   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  * 3. All advertising materials mentioning features or use of this software
  46  *    must display the following acknowledgement:
  47  *      This product includes software developed by the University of
  48  *      California, Berkeley and its contributors.
  49  * 4. Neither the name of the University nor the names of its contributors
  50  *    may be used to endorse or promote products derived from this software
  51  *    without specific prior written permission.
  52  *
  53  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  54  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  55  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  56  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  57  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  58  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  59  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  60  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  61  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  62  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  63  * SUCH DAMAGE.
  64  *
  65  *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
  66  */
  67
  68 #include <sys/param.h>
  69 #include <sys/mbuf.h>
  70 #include <sys/systm.h>
  71 #include <netinet/in.h>
  72 #include <netinet/ip6.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 #if 0
 104         int srcifid = 0, dstifid = 0;
 105 #endif
 106         struct ip6_hdr *ip6;
 107         union {
 108                 u_int16_t phs[4];
 109                 struct {
 110                         u_int32_t       ph_len;
 111                         u_int8_t        ph_zero[3];
 112                         u_int8_t        ph_nxt;
 113                 } ph __attribute__((__packed__));
 114         } uph;
 115         union {
 116                 u_int8_t        c[2];
 117                 u_int16_t       s;
 118         } s_util;
 119         union {
 120                 u_int16_t s[2];
 121                 u_int32_t l;
 122         } l_util;
 123
 124         /* sanity check */
 125         if (m->m_pkthdr.len < off + len) {
 126                 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)\n",
 127                         m->m_pkthdr.len, off, len);
 128         }
 129
 130         bzero(&uph, sizeof(uph));
 131
 132         /*
 133          * First create IP6 pseudo header and calculate a summary.
 134          */
 135         ip6 = mtod(m, struct ip6_hdr *);
 136 #if 0
 137         if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) {
 138                 srcifid = ip6->ip6_src.s6_addr16[1];
 139                 ip6->ip6_src.s6_addr16[1] = 0;
 140         }
 141         if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) {
 142                 dstifid = ip6->ip6_dst.s6_addr16[1];
 143                 ip6->ip6_dst.s6_addr16[1] = 0;
 144         }
 145 #endif
 146         w = (u_int16_t *)&ip6->ip6_src;
 147         uph.ph.ph_len = htonl(len);
 148         uph.ph.ph_nxt = nxt;
 149
 150         /* IPv6 source address */
 151         sum += w[0];
 152         if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
 153                 sum += w[1];
 154         sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
 155         sum += w[6]; sum += w[7];
 156         /* IPv6 destination address */
 157         sum += w[8];
 158         if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
 159                 sum += w[9];
 160         sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13];
 161         sum += w[14]; sum += w[15];
 162         /* Payload length and upper layer identifier */
 163         sum += uph.phs[0];  sum += uph.phs[1];
 164         sum += uph.phs[2];  sum += uph.phs[3];
 165
 166 #if 0
 167         if (srcifid)
 168                 ip6->ip6_src.s6_addr16[1] = srcifid;
 169         if (dstifid)
 170                 ip6->ip6_dst.s6_addr16[1] = dstifid;
 171 #endif
 172         /*
 173          * Secondly calculate a summary of the first mbuf excluding offset.
 174          */
 175         while (m != NULL && off > 0) {
 176                 if (m->m_len <= off)
 177                         off -= m->m_len;
 178                 else
 179                         break;
 180                 m = m->m_next;
 181         }
 182         w = (u_int16_t *)(mtod(m, u_char *) + off);
 183         mlen = m->m_len - off;
 184         if (len < mlen)
 185                 mlen = len;
 186         len -= mlen;
 187         /*
 188          * Force to even boundary.
 189          */
 190         if ((1 & (long) w) && (mlen > 0)) {
 191                 REDUCE;
 192                 sum <<= 8;
 193                 s_util.c[0] = *(u_char *)w;
 194                 w = (u_int16_t *)((char *)w + 1);
 195                 mlen--;
 196                 byte_swapped = 1;
 197         }
 198         /*
 199          * Unroll the loop to make overhead from
 200          * branches &c small.
 201          */
 202         while ((mlen -= 32) >= 0) {
 203                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 204                 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
 205                 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
 206                 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
 207                 w += 16;
 208         }
 209         mlen += 32;
 210         while ((mlen -= 8) >= 0) {
 211                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 212                 w += 4;
 213         }
 214         mlen += 8;
 215         if (mlen == 0 && byte_swapped == 0)
 216                 goto next;
 217         REDUCE;
 218         while ((mlen -= 2) >= 0) {
 219                 sum += *w++;
 220         }
 221         if (byte_swapped) {
 222                 REDUCE;
 223                 sum <<= 8;
 224                 byte_swapped = 0;
 225                 if (mlen == -1) {
 226                         s_util.c[1] = *(char *)w;
 227                         sum += s_util.s;
 228                         mlen = 0;
 229                 } else
 230                         mlen = -1;
 231         } else if (mlen == -1)
 232                 s_util.c[0] = *(char *)w;
 233  next:
 234         m = m->m_next;
 235
 236         /*
 237          * Lastly calculate a summary of the rest of mbufs.
 238          */
 239
 240         for (;m && len; m = m->m_next) {
 241                 if (m->m_len == 0)
 242                         continue;
 243                 w = mtod(m, u_int16_t *);
 244                 if (mlen == -1) {
 245                         /*
 246                          * The first byte of this mbuf is the continuation
 247                          * of a word spanning between this mbuf and the
 248                          * last mbuf.
 249                          *
 250                          * s_util.c[0] is already saved when scanning previous
 251                          * mbuf.
 252                          */
 253                         s_util.c[1] = *(char *)w;
 254                         sum += s_util.s;
 255                         w = (u_int16_t *)((char *)w + 1);
 256                         mlen = m->m_len - 1;
 257                         len--;
 258                 } else
 259                         mlen = m->m_len;
 260                 if (len < mlen)
 261                         mlen = len;
 262                 len -= mlen;
 263                 /*
 264                  * Force to even boundary.
 265                  */
 266                 if ((1 & (long) w) && (mlen > 0)) {
 267                         REDUCE;
 268                         sum <<= 8;
 269                         s_util.c[0] = *(u_char *)w;
 270                         w = (u_int16_t *)((char *)w + 1);
 271                         mlen--;
 272                         byte_swapped = 1;
 273                 }
 274                 /*
 275                  * Unroll the loop to make overhead from
 276                  * branches &c small.
 277                  */
 278                 while ((mlen -= 32) >= 0) {
 279                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 280                         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
 281                         sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
 282                         sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
 283                         w += 16;
 284                 }
 285                 mlen += 32;
 286                 while ((mlen -= 8) >= 0) {
 287                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 288                         w += 4;
 289                 }
 290                 mlen += 8;
 291                 if (mlen == 0 && byte_swapped == 0)
 292                         continue;
 293                 REDUCE;
 294                 while ((mlen -= 2) >= 0) {
 295                         sum += *w++;
 296                 }
 297                 if (byte_swapped) {
 298                         REDUCE;
 299                         sum <<= 8;
 300                         byte_swapped = 0;
 301                         if (mlen == -1) {
 302                                 s_util.c[1] = *(char *)w;
 303                                 sum += s_util.s;
 304                                 mlen = 0;
 305                         } else
 306                                 mlen = -1;
 307                 } else if (mlen == -1)
 308                         s_util.c[0] = *(char *)w;
 309         }
 310         if (len)
 311                 panic("in6_cksum: out of data\n");
 312         if (mlen == -1) {
 313                 /* The last mbuf has odd # of bytes. Follow the
 314                    standard (the odd byte may be shifted left by 8 bits
 315                    or not as determined by endian-ness of the machine) */
 316                 s_util.c[1] = 0;
 317                 sum += s_util.s;
 318         }
 319         REDUCE;
 320         return (~sum & 0xffff);
 321 }