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 <kern/debug.h>
  72 #include <netinet/in.h>
  73 #include <netinet/ip6.h>
  74
  75 #include <net/net_osdep.h>
  76
  77 /*
  78  * Checksum routine for Internet Protocol family headers (Portable Version).
  79  *
  80  * This routine is very heavily used in the network
  81  * code and should be modified for each CPU to be as fast as possible.
  82  */
  83
  84 #define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
  85 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
  86
  87 /*
  88  * m MUST contain a continuous IP6 header.
  89  * off is a offset where TCP/UDP/ICMP6 header starts.
  90  * len is a total length of a transport segment.
  91  * (e.g. TCP header + TCP payload)
  92  */
  93
  94 u_int16_t
  95 inet6_cksum(struct mbuf *m, unsigned int nxt, unsigned int off,
  96     unsigned int len)
  97 {
  98         u_int16_t *w;
  99         int sum = 0;
 100         int mlen = 0;
 101         int byte_swapped = 0;
 102         struct ip6_hdr *ip6;
 103         union {
 104                 u_int16_t phs[4];
 105                 struct {
 106                         u_int32_t       ph_len;
 107                         u_int8_t        ph_zero[3];
 108                         u_int8_t        ph_nxt;
 109                 } ph __attribute__((__packed__));
 110         } uph;
 111         union {
 112                 u_int8_t        c[2];
 113                 u_int16_t       s;
 114         } s_util;
 115         union {
 116                 u_int16_t s[2];
 117                 u_int32_t l;
 118         } l_util;
 119
 120         /* sanity check */
 121         if (m->m_pkthdr.len < off + len) {
 122                 panic("inet6_cksum: mbuf len (%d) < off+len (%d+%d)\n",
 123                     m->m_pkthdr.len, off, len);
 124         }
 125
 126         if (nxt != 0) {
 127                 bzero(&uph, sizeof (uph));
 128
 129                 /*
 130                  * First create IP6 pseudo header and calculate a summary.
 131                  */
 132                 ip6 = mtod(m, struct ip6_hdr *);
 133                 w = (u_int16_t *)&ip6->ip6_src;
 134                 uph.ph.ph_len = htonl(len);
 135                 uph.ph.ph_nxt = nxt;
 136
 137                 /* IPv6 source address */
 138                 sum += w[0];
 139                 if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
 140                         sum += w[1];
 141                 sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
 142                 sum += w[6]; sum += w[7];
 143                 /* IPv6 destination address */
 144                 sum += w[8];
 145                 if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
 146                         sum += w[9];
 147                 sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13];
 148                 sum += w[14]; sum += w[15];
 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         /*
 155          * Secondly calculate a summary of the first mbuf excluding offset.
 156          */
 157         while (m != NULL && off > 0) {
 158                 if (m->m_len <= off)
 159                         off -= m->m_len;
 160                 else
 161                         break;
 162                 m = m->m_next;
 163         }
 164         w = (u_int16_t *)(mtod(m, u_char *) + off);
 165         mlen = m->m_len - off;
 166         if (len < mlen)
 167                 mlen = len;
 168         len -= mlen;
 169         /*
 170          * Force to even boundary.
 171          */
 172         if ((1 & (long) w) && (mlen > 0)) {
 173                 REDUCE;
 174                 sum <<= 8;
 175                 s_util.c[0] = *(u_char *)w;
 176                 w = (u_int16_t *)((char *)w + 1);
 177                 mlen--;
 178                 byte_swapped = 1;
 179         }
 180         /*
 181          * Unroll the loop to make overhead from
 182          * branches &c small.
 183          */
 184         while ((mlen -= 32) >= 0) {
 185                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 186                 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
 187                 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
 188                 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
 189                 w += 16;
 190         }
 191         mlen += 32;
 192         while ((mlen -= 8) >= 0) {
 193                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 194                 w += 4;
 195         }
 196         mlen += 8;
 197         if (mlen == 0 && byte_swapped == 0)
 198                 goto next;
 199         REDUCE;
 200         while ((mlen -= 2) >= 0) {
 201                 sum += *w++;
 202         }
 203         if (byte_swapped) {
 204                 REDUCE;
 205                 sum <<= 8;
 206                 byte_swapped = 0;
 207                 if (mlen == -1) {
 208                         s_util.c[1] = *(char *)w;
 209                         sum += s_util.s;
 210                         mlen = 0;
 211                 } else
 212                         mlen = -1;
 213         } else if (mlen == -1)
 214                 s_util.c[0] = *(char *)w;
 215  next:
 216         m = m->m_next;
 217
 218         /*
 219          * Lastly calculate a summary of the rest of mbufs.
 220          */
 221
 222         for (;m && len; m = m->m_next) {
 223                 if (m->m_len == 0)
 224                         continue;
 225                 w = mtod(m, u_int16_t *);
 226                 if (mlen == -1) {
 227                         /*
 228                          * The first byte of this mbuf is the continuation
 229                          * of a word spanning between this mbuf and the
 230                          * last mbuf.
 231                          *
 232                          * s_util.c[0] is already saved when scanning previous
 233                          * mbuf.
 234                          */
 235                         s_util.c[1] = *(char *)w;
 236                         sum += s_util.s;
 237                         w = (u_int16_t *)((char *)w + 1);
 238                         mlen = m->m_len - 1;
 239                         len--;
 240                 } else
 241                         mlen = m->m_len;
 242                 if (len < mlen)
 243                         mlen = len;
 244                 len -= mlen;
 245                 /*
 246                  * Force to even boundary.
 247                  */
 248                 if ((1 & (long) w) && (mlen > 0)) {
 249                         REDUCE;
 250                         sum <<= 8;
 251                         s_util.c[0] = *(u_char *)w;
 252                         w = (u_int16_t *)((char *)w + 1);
 253                         mlen--;
 254                         byte_swapped = 1;
 255                 }
 256                 /*
 257                  * Unroll the loop to make overhead from
 258                  * branches &c small.
 259                  */
 260                 while ((mlen -= 32) >= 0) {
 261                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 262                         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
 263                         sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
 264                         sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
 265                         w += 16;
 266                 }
 267                 mlen += 32;
 268                 while ((mlen -= 8) >= 0) {
 269                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 270                         w += 4;
 271                 }
 272                 mlen += 8;
 273                 if (mlen == 0 && byte_swapped == 0)
 274                         continue;
 275                 REDUCE;
 276                 while ((mlen -= 2) >= 0) {
 277                         sum += *w++;
 278                 }
 279                 if (byte_swapped) {
 280                         REDUCE;
 281                         sum <<= 8;
 282                         byte_swapped = 0;
 283                         if (mlen == -1) {
 284                                 s_util.c[1] = *(char *)w;
 285                                 sum += s_util.s;
 286                                 mlen = 0;
 287                         } else
 288                                 mlen = -1;
 289                 } else if (mlen == -1)
 290                         s_util.c[0] = *(char *)w;
 291         }
 292         if (len)
 293                 printf("inet6_cksum: out of data by %d\n", len);
 294         if (mlen == -1) {
 295                 /* The last mbuf has odd # of bytes. Follow the
 296                    standard (the odd byte may be shifted left by 8 bits
 297                    or not as determined by endian-ness of the machine) */
 298                 s_util.c[1] = 0;
 299                 sum += s_util.s;
 300         }
 301         REDUCE;
 302         return (~sum & 0xffff);
 303 }