bsd/netinet6/in6_cksum.c

   1 /*      $KAME: in6_cksum.c,v 1.5 2000/02/22 14:04:17 itojun Exp $       */
   2
   3 /*
   4  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the project nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 /*
  33  * Copyright (c) 1988, 1992, 1993
  34  *      The Regents of the University of California.  All rights reserved.
  35  *
  36  * Redistribution and use in source and binary forms, with or without
  37  * modification, are permitted provided that the following conditions
  38  * are met:
  39  * 1. Redistributions of source code must retain the above copyright
  40  *    notice, this list of conditions and the following disclaimer.
  41  * 2. Redistributions in binary form must reproduce the above copyright
  42  *    notice, this list of conditions and the following disclaimer in the
  43  *    documentation and/or other materials provided with the distribution.
  44  * 3. All advertising materials mentioning features or use of this software
  45  *    must display the following acknowledgement:
  46  *      This product includes software developed by the University of
  47  *      California, Berkeley and its contributors.
  48  * 4. Neither the name of the University nor the names of its contributors
  49  *    may be used to endorse or promote products derived from this software
  50  *    without specific prior written permission.
  51  *
  52  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  53  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  54  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  55  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  56  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  57  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  58  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  59  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  60  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  61  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  62  * SUCH DAMAGE.
  63  *
  64  *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
  65  */
  66
  67 #include <sys/param.h>
  68 #include <sys/mbuf.h>
  69 #include <sys/systm.h>
  70 #include <netinet/in.h>
  71 #include <netinet/ip6.h>
  72
  73 #include <net/net_osdep.h>
  74
  75 /*
  76  * Checksum routine for Internet Protocol family headers (Portable Version).
  77  *
  78  * This routine is very heavily used in the network
  79  * code and should be modified for each CPU to be as fast as possible.
  80  */
  81
  82 #define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
  83 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
  84
  85 static union {
  86         u_int16_t phs[4];
  87         struct {
  88                 u_int32_t       ph_len;
  89                 u_int8_t        ph_zero[3];
  90                 u_int8_t        ph_nxt;
  91         } ph;
  92 } uph;
  93
  94 /*
  95  * m MUST contain a continuous IP6 header.
  96  * off is a offset where TCP/UDP/ICMP6 header starts.
  97  * len is a total length of a transport segment.
  98  * (e.g. TCP header + TCP payload)
  99  */
 100
 101 int
 102 in6_cksum(m, nxt, off, len)
 103         register struct mbuf *m;
 104         u_int8_t nxt;
 105         u_int32_t off, len;
 106 {
 107         register u_int16_t *w;
 108         register int sum = 0;
 109         register int mlen = 0;
 110         int byte_swapped = 0;
 111 #if 0
 112         int srcifid = 0, dstifid = 0;
 113 #endif
 114         struct ip6_hdr *ip6;
 115
 116         union {
 117                 u_int8_t        c[2];
 118                 u_int16_t       s;
 119         } s_util;
 120         union {
 121                 u_int16_t s[2];
 122                 u_int32_t l;
 123         } l_util;
 124
 125         /* sanity check */
 126         if (m->m_pkthdr.len < off + len) {
 127                 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)\n",
 128                         m->m_pkthdr.len, off, len);
 129         }
 130
 131         /*
 132          * First create IP6 pseudo header and calculate a summary.
 133          */
 134         ip6 = mtod(m, struct ip6_hdr *);
 135 #if 0
 136         if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) {
 137                 srcifid = ip6->ip6_src.s6_addr16[1];
 138                 ip6->ip6_src.s6_addr16[1] = 0;
 139         }
 140         if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) {
 141                 dstifid = ip6->ip6_dst.s6_addr16[1];
 142                 ip6->ip6_dst.s6_addr16[1] = 0;
 143         }
 144 #endif
 145         w = (u_int16_t *)&ip6->ip6_src;
 146         uph.ph.ph_len = htonl(len);
 147         uph.ph.ph_nxt = nxt;
 148
 149         /* IPv6 source address */
 150         sum += w[0];
 151         if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
 152                 sum += w[1];
 153         sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
 154         sum += w[6]; sum += w[7];
 155         /* IPv6 destination address */
 156         sum += w[8];
 157         if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
 158                 sum += w[9];
 159         sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13];
 160         sum += w[14]; sum += w[15];
 161         /* Payload length and upper layer identifier */
 162         sum += uph.phs[0];  sum += uph.phs[1];
 163         sum += uph.phs[2];  sum += uph.phs[3];
 164
 165 #if 0
 166         if (srcifid)
 167                 ip6->ip6_src.s6_addr16[1] = srcifid;
 168         if (dstifid)
 169                 ip6->ip6_dst.s6_addr16[1] = dstifid;
 170 #endif
 171         /*
 172          * Secondly calculate a summary of the first mbuf excluding offset.
 173          */
 174         while (m != NULL && off > 0) {
 175                 if (m->m_len <= off)
 176                         off -= m->m_len;
 177                 else
 178                         break;
 179                 m = m->m_next;
 180         }
 181         w = (u_int16_t *)(mtod(m, u_char *) + off);
 182         mlen = m->m_len - off;
 183         if (len < mlen)
 184                 mlen = len;
 185         len -= mlen;
 186         /*
 187          * Force to even boundary.
 188          */
 189         if ((1 & (long) w) && (mlen > 0)) {
 190                 REDUCE;
 191                 sum <<= 8;
 192                 s_util.c[0] = *(u_char *)w;
 193                 w = (u_int16_t *)((char *)w + 1);
 194                 mlen--;
 195                 byte_swapped = 1;
 196         }
 197         /*
 198          * Unroll the loop to make overhead from
 199          * branches &c small.
 200          */
 201         while ((mlen -= 32) >= 0) {
 202                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 203                 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
 204                 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
 205                 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
 206                 w += 16;
 207         }
 208         mlen += 32;
 209         while ((mlen -= 8) >= 0) {
 210                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 211                 w += 4;
 212         }
 213         mlen += 8;
 214         if (mlen == 0 && byte_swapped == 0)
 215                 goto next;
 216         REDUCE;
 217         while ((mlen -= 2) >= 0) {
 218                 sum += *w++;
 219         }
 220         if (byte_swapped) {
 221                 REDUCE;
 222                 sum <<= 8;
 223                 byte_swapped = 0;
 224                 if (mlen == -1) {
 225                         s_util.c[1] = *(char *)w;
 226                         sum += s_util.s;
 227                         mlen = 0;
 228                 } else
 229                         mlen = -1;
 230         } else if (mlen == -1)
 231                 s_util.c[0] = *(char *)w;
 232  next:
 233         m = m->m_next;
 234
 235         /*
 236          * Lastly calculate a summary of the rest of mbufs.
 237          */
 238
 239         for (;m && len; m = m->m_next) {
 240                 if (m->m_len == 0)
 241                         continue;
 242                 w = mtod(m, u_int16_t *);
 243                 if (mlen == -1) {
 244                         /*
 245                          * The first byte of this mbuf is the continuation
 246                          * of a word spanning between this mbuf and the
 247                          * last mbuf.
 248                          *
 249                          * s_util.c[0] is already saved when scanning previous
 250                          * mbuf.
 251                          */
 252                         s_util.c[1] = *(char *)w;
 253                         sum += s_util.s;
 254                         w = (u_int16_t *)((char *)w + 1);
 255                         mlen = m->m_len - 1;
 256                         len--;
 257                 } else
 258                         mlen = m->m_len;
 259                 if (len < mlen)
 260                         mlen = len;
 261                 len -= mlen;
 262                 /*
 263                  * Force to even boundary.
 264                  */
 265                 if ((1 & (long) w) && (mlen > 0)) {
 266                         REDUCE;
 267                         sum <<= 8;
 268                         s_util.c[0] = *(u_char *)w;
 269                         w = (u_int16_t *)((char *)w + 1);
 270                         mlen--;
 271                         byte_swapped = 1;
 272                 }
 273                 /*
 274                  * Unroll the loop to make overhead from
 275                  * branches &c small.
 276                  */
 277                 while ((mlen -= 32) >= 0) {
 278                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 279                         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
 280                         sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
 281                         sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
 282                         w += 16;
 283                 }
 284                 mlen += 32;
 285                 while ((mlen -= 8) >= 0) {
 286                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 287                         w += 4;
 288                 }
 289                 mlen += 8;
 290                 if (mlen == 0 && byte_swapped == 0)
 291                         continue;
 292                 REDUCE;
 293                 while ((mlen -= 2) >= 0) {
 294                         sum += *w++;
 295                 }
 296                 if (byte_swapped) {
 297                         REDUCE;
 298                         sum <<= 8;
 299                         byte_swapped = 0;
 300                         if (mlen == -1) {
 301                                 s_util.c[1] = *(char *)w;
 302                                 sum += s_util.s;
 303                                 mlen = 0;
 304                         } else
 305                                 mlen = -1;
 306                 } else if (mlen == -1)
 307                         s_util.c[0] = *(char *)w;
 308         }
 309         if (len)
 310                 panic("in6_cksum: out of data\n");
 311         if (mlen == -1) {
 312                 /* The last mbuf has odd # of bytes. Follow the
 313                    standard (the odd byte may be shifted left by 8 bits
 314                    or not as determined by endian-ness of the machine) */
 315                 s_util.c[1] = 0;
 316                 sum += s_util.s;
 317         }
 318         REDUCE;
 319         return (~sum & 0xffff);
 320 }