sys/netinet6/in6_cksum.c

   1 /*      $FreeBSD: src/sys/netinet6/in6_cksum.c,v 1.1.2.4 2003/05/06 06:46:58 suz Exp $  */
   2 /*      $DragonFly: src/sys/netinet6/in6_cksum.c,v 1.4 2006/10/24 06:18:42 hsu Exp $    */
   3 /*      $KAME: in6_cksum.c,v 1.10 2000/12/03 00:53:59 itojun Exp $      */
   4
   5 /*
   6  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. Neither the name of the project nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 /*
  35  * Copyright (c) 1988, 1992, 1993
  36  *      The Regents of the University of California.  All rights reserved.
  37  *
  38  * Redistribution and use in source and binary forms, with or without
  39  * modification, are permitted provided that the following conditions
  40  * are met:
  41  * 1. Redistributions of source code must retain the above copyright
  42  *    notice, this list of conditions and the following disclaimer.
  43  * 2. Redistributions in binary form must reproduce the above copyright
  44  *    notice, this list of conditions and the following disclaimer in the
  45  *    documentation and/or other materials provided with the distribution.
  46  * 3. Neither the name of the University nor the names of its contributors
  47  *    may be used to endorse or promote products derived from this software
  48  *    without specific prior written permission.
  49  *
  50  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  51  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  52  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  53  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  54  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  55  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  56  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  57  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  58  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  59  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  60  * SUCH DAMAGE.
  61  *
  62  *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
  63  */
  64
  65 #include <sys/param.h>
  66 #include <sys/mbuf.h>
  67 #include <sys/systm.h>
  68 #include <netinet/in.h>
  69 #include <netinet/ip6.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 a 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         union {
  99                 u_int16_t phs[4];
 100                 struct {
 101                         u_int32_t       ph_len;
 102                         u_int8_t        ph_zero[3];
 103                         u_int8_t        ph_nxt;
 104                 } ph __attribute__((__packed__));
 105         } uph;
 106         union {
 107                 u_int8_t        c[2];
 108                 u_int16_t       s;
 109         } s_util;
 110         union {
 111                 u_int16_t s[2];
 112                 u_int32_t l;
 113         } l_util;
 114
 115         /* sanity check */
 116         if (m->m_pkthdr.len < off + len) {
 117                 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)",
 118                         m->m_pkthdr.len, off, len);
 119         }
 120
 121         bzero(&uph, sizeof(uph));
 122
 123         /*
 124          * First create IP6 pseudo header and calculate a summary.
 125          */
 126         ip6 = mtod(m, struct ip6_hdr *);
 127         w = (u_int16_t *)&ip6->ip6_src;
 128         uph.ph.ph_len = htonl(len);
 129         uph.ph.ph_nxt = nxt;
 130
 131         /* IPv6 source address */
 132         sum += w[0];
 133         if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
 134                 sum += w[1];
 135         sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
 136         sum += w[6]; sum += w[7];
 137         /* IPv6 destination address */
 138         sum += w[8];
 139         if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
 140                 sum += w[9];
 141         sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13];
 142         sum += w[14]; sum += w[15];
 143         /* Payload length and upper layer identifier */
 144         sum += uph.phs[0];  sum += uph.phs[1];
 145         sum += uph.phs[2];  sum += uph.phs[3];
 146
 147         /*
 148          * Secondly calculate a summary of the first mbuf excluding offset.
 149          */
 150         while (m != NULL && off > 0) {
 151                 if (m->m_len <= off)
 152                         off -= m->m_len;
 153                 else
 154                         break;
 155                 m = m->m_next;
 156         }
 157         w = (u_int16_t *)(mtod(m, u_char *) + off);
 158         mlen = m->m_len - off;
 159         if (len < mlen)
 160                 mlen = len;
 161         len -= mlen;
 162         /*
 163          * Force to even boundary.
 164          */
 165         if ((1 & (long) w) && (mlen > 0)) {
 166                 REDUCE;
 167                 sum <<= 8;
 168                 s_util.c[0] = *(u_char *)w;
 169                 w = (u_int16_t *)((char *)w + 1);
 170                 mlen--;
 171                 byte_swapped = 1;
 172         }
 173         /*
 174          * Unroll the loop to make overhead from
 175          * branches &c small.
 176          */
 177         while ((mlen -= 32) >= 0) {
 178                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 179                 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
 180                 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
 181                 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
 182                 w += 16;
 183         }
 184         mlen += 32;
 185         while ((mlen -= 8) >= 0) {
 186                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 187                 w += 4;
 188         }
 189         mlen += 8;
 190         if (mlen == 0 && byte_swapped == 0)
 191                 goto next;
 192         REDUCE;
 193         while ((mlen -= 2) >= 0) {
 194                 sum += *w++;
 195         }
 196         if (byte_swapped) {
 197                 REDUCE;
 198                 sum <<= 8;
 199                 byte_swapped = 0;
 200                 if (mlen == -1) {
 201                         s_util.c[1] = *(char *)w;
 202                         sum += s_util.s;
 203                         mlen = 0;
 204                 } else
 205                         mlen = -1;
 206         } else if (mlen == -1)
 207                 s_util.c[0] = *(char *)w;
 208 next:
 209         m = m->m_next;
 210
 211         /*
 212          * Lastly calculate a summary of the rest of mbufs.
 213          */
 214
 215         for (;m && len; m = m->m_next) {
 216                 if (m->m_len == 0)
 217                         continue;
 218                 w = mtod(m, u_int16_t *);
 219                 if (mlen == -1) {
 220                         /*
 221                          * The first byte of this mbuf is the continuation
 222                          * of a word spanning between this mbuf and the
 223                          * last mbuf.
 224                          *
 225                          * s_util.c[0] is already saved when scanning previous
 226                          * mbuf.
 227                          */
 228                         s_util.c[1] = *(char *)w;
 229                         sum += s_util.s;
 230                         w = (u_int16_t *)((char *)w + 1);
 231                         mlen = m->m_len - 1;
 232                         len--;
 233                 } else
 234                         mlen = m->m_len;
 235                 if (len < mlen)
 236                         mlen = len;
 237                 len -= mlen;
 238                 /*
 239                  * Force to even boundary.
 240                  */
 241                 if ((1 & (long) w) && (mlen > 0)) {
 242                         REDUCE;
 243                         sum <<= 8;
 244                         s_util.c[0] = *(u_char *)w;
 245                         w = (u_int16_t *)((char *)w + 1);
 246                         mlen--;
 247                         byte_swapped = 1;
 248                 }
 249                 /*
 250                  * Unroll the loop to make overhead from
 251                  * branches &c small.
 252                  */
 253                 while ((mlen -= 32) >= 0) {
 254                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 255                         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
 256                         sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
 257                         sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
 258                         w += 16;
 259                 }
 260                 mlen += 32;
 261                 while ((mlen -= 8) >= 0) {
 262                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 263                         w += 4;
 264                 }
 265                 mlen += 8;
 266                 if (mlen == 0 && byte_swapped == 0)
 267                         continue;
 268                 REDUCE;
 269                 while ((mlen -= 2) >= 0) {
 270                         sum += *w++;
 271                 }
 272                 if (byte_swapped) {
 273                         REDUCE;
 274                         sum <<= 8;
 275                         byte_swapped = 0;
 276                         if (mlen == -1) {
 277                                 s_util.c[1] = *(char *)w;
 278                                 sum += s_util.s;
 279                                 mlen = 0;
 280                         } else
 281                                 mlen = -1;
 282                 } else if (mlen == -1)
 283                         s_util.c[0] = *(char *)w;
 284         }
 285         if (len)
 286                 panic("in6_cksum: out of data");
 287         if (mlen == -1) {
 288                 /* The last mbuf has odd # of bytes. Follow the
 289                    standard (the odd byte may be shifted left by 8 bits
 290                    or not as determined by endian-ness of the machine) */
 291                 s_util.c[1] = 0;
 292                 sum += s_util.s;
 293         }
 294         REDUCE;
 295         return (~sum & 0xffff);
 296 }