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. All advertising materials mentioning features or use of this software
  47  *    must display the following acknowledgement:
  48  *      This product includes software developed by the University of
  49  *      California, Berkeley and its contributors.
  50  * 4. Neither the name of the University nor the names of its contributors
  51  *    may be used to endorse or promote products derived from this software
  52  *    without specific prior written permission.
  53  *
  54  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  55  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  56  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  57  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  58  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  59  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  60  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  61  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  62  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  63  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  64  * SUCH DAMAGE.
  65  *
  66  *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
  67  */
  68
  69 #include <sys/param.h>
  70 #include <sys/mbuf.h>
  71 #include <sys/systm.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 int
  95 in6_cksum(struct mbuf *m, u_int8_t nxt, u_int32_t off, u_int32_t len)
  96 {
  97         u_int16_t *w;
  98         int sum = 0;
  99         int mlen = 0;
 100         int byte_swapped = 0;
 101 #if 0
 102         int srcifid = 0, dstifid = 0;
 103 #endif
 104         struct ip6_hdr *ip6;
 105         union {
 106                 u_int16_t phs[4];
 107                 struct {
 108                         u_int32_t       ph_len;
 109                         u_int8_t        ph_zero[3];
 110                         u_int8_t        ph_nxt;
 111                 } ph __attribute__((__packed__));
 112         } uph;
 113         union {
 114                 u_int8_t        c[2];
 115                 u_int16_t       s;
 116         } s_util;
 117         union {
 118                 u_int16_t s[2];
 119                 u_int32_t l;
 120         } l_util;
 121
 122         /* sanity check */
 123         if (m->m_pkthdr.len < off + len) {
 124                 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)",
 125                         m->m_pkthdr.len, off, len);
 126         }
 127
 128         bzero(&uph, sizeof(uph));
 129
 130         /*
 131          * First create IP6 pseudo header and calculate a summary.
 132          */
 133         ip6 = mtod(m, struct ip6_hdr *);
 134 #if 0
 135         if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) {
 136                 srcifid = ip6->ip6_src.s6_addr16[1];
 137                 ip6->ip6_src.s6_addr16[1] = 0;
 138         }
 139         if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) {
 140                 dstifid = ip6->ip6_dst.s6_addr16[1];
 141                 ip6->ip6_dst.s6_addr16[1] = 0;
 142         }
 143 #endif
 144         w = (u_int16_t *)&ip6->ip6_src;
 145         uph.ph.ph_len = htonl(len);
 146         uph.ph.ph_nxt = nxt;
 147
 148         /* IPv6 source address */
 149         sum += w[0];
 150         if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
 151                 sum += w[1];
 152         sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
 153         sum += w[6]; sum += w[7];
 154         /* IPv6 destination address */
 155         sum += w[8];
 156         if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
 157                 sum += w[9];
 158         sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13];
 159         sum += w[14]; sum += w[15];
 160         /* Payload length and upper layer identifier */
 161         sum += uph.phs[0];  sum += uph.phs[1];
 162         sum += uph.phs[2];  sum += uph.phs[3];
 163
 164 #if 0
 165         if (srcifid)
 166                 ip6->ip6_src.s6_addr16[1] = srcifid;
 167         if (dstifid)
 168                 ip6->ip6_dst.s6_addr16[1] = dstifid;
 169 #endif
 170         /*
 171          * Secondly calculate a summary of the first mbuf excluding offset.
 172          */
 173         while (m != NULL && off > 0) {
 174                 if (m->m_len <= off)
 175                         off -= m->m_len;
 176                 else
 177                         break;
 178                 m = m->m_next;
 179         }
 180         w = (u_int16_t *)(mtod(m, u_char *) + off);
 181         mlen = m->m_len - off;
 182         if (len < mlen)
 183                 mlen = len;
 184         len -= mlen;
 185         /*
 186          * Force to even boundary.
 187          */
 188         if ((1 & (long) w) && (mlen > 0)) {
 189                 REDUCE;
 190                 sum <<= 8;
 191                 s_util.c[0] = *(u_char *)w;
 192                 w = (u_int16_t *)((char *)w + 1);
 193                 mlen--;
 194                 byte_swapped = 1;
 195         }
 196         /*
 197          * Unroll the loop to make overhead from
 198          * branches &c small.
 199          */
 200         while ((mlen -= 32) >= 0) {
 201                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 202                 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
 203                 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
 204                 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
 205                 w += 16;
 206         }
 207         mlen += 32;
 208         while ((mlen -= 8) >= 0) {
 209                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 210                 w += 4;
 211         }
 212         mlen += 8;
 213         if (mlen == 0 && byte_swapped == 0)
 214                 goto next;
 215         REDUCE;
 216         while ((mlen -= 2) >= 0) {
 217                 sum += *w++;
 218         }
 219         if (byte_swapped) {
 220                 REDUCE;
 221                 sum <<= 8;
 222                 byte_swapped = 0;
 223                 if (mlen == -1) {
 224                         s_util.c[1] = *(char *)w;
 225                         sum += s_util.s;
 226                         mlen = 0;
 227                 } else
 228                         mlen = -1;
 229         } else if (mlen == -1)
 230                 s_util.c[0] = *(char *)w;
 231 next:
 232         m = m->m_next;
 233
 234         /*
 235          * Lastly calculate a summary of the rest of mbufs.
 236          */
 237
 238         for (;m && len; m = m->m_next) {
 239                 if (m->m_len == 0)
 240                         continue;
 241                 w = mtod(m, u_int16_t *);
 242                 if (mlen == -1) {
 243                         /*
 244                          * The first byte of this mbuf is the continuation
 245                          * of a word spanning between this mbuf and the
 246                          * last mbuf.
 247                          *
 248                          * s_util.c[0] is already saved when scanning previous
 249                          * mbuf.
 250                          */
 251                         s_util.c[1] = *(char *)w;
 252                         sum += s_util.s;
 253                         w = (u_int16_t *)((char *)w + 1);
 254                         mlen = m->m_len - 1;
 255                         len--;
 256                 } else
 257                         mlen = m->m_len;
 258                 if (len < mlen)
 259                         mlen = len;
 260                 len -= mlen;
 261                 /*
 262                  * Force to even boundary.
 263                  */
 264                 if ((1 & (long) w) && (mlen > 0)) {
 265                         REDUCE;
 266                         sum <<= 8;
 267                         s_util.c[0] = *(u_char *)w;
 268                         w = (u_int16_t *)((char *)w + 1);
 269                         mlen--;
 270                         byte_swapped = 1;
 271                 }
 272                 /*
 273                  * Unroll the loop to make overhead from
 274                  * branches &c small.
 275                  */
 276                 while ((mlen -= 32) >= 0) {
 277                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 278                         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
 279                         sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
 280                         sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
 281                         w += 16;
 282                 }
 283                 mlen += 32;
 284                 while ((mlen -= 8) >= 0) {
 285                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 286                         w += 4;
 287                 }
 288                 mlen += 8;
 289                 if (mlen == 0 && byte_swapped == 0)
 290                         continue;
 291                 REDUCE;
 292                 while ((mlen -= 2) >= 0) {
 293                         sum += *w++;
 294                 }
 295                 if (byte_swapped) {
 296                         REDUCE;
 297                         sum <<= 8;
 298                         byte_swapped = 0;
 299                         if (mlen == -1) {
 300                                 s_util.c[1] = *(char *)w;
 301                                 sum += s_util.s;
 302                                 mlen = 0;
 303                         } else
 304                                 mlen = -1;
 305                 } else if (mlen == -1)
 306                         s_util.c[0] = *(char *)w;
 307         }
 308         if (len)
 309                 panic("in6_cksum: out of data");
 310         if (mlen == -1) {
 311                 /* The last mbuf has odd # of bytes. Follow the
 312                    standard (the odd byte may be shifted left by 8 bits
 313                    or not as determined by endian-ness of the machine) */
 314                 s_util.c[1] = 0;
 315                 sum += s_util.s;
 316         }
 317         REDUCE;
 318         return (~sum & 0xffff);
 319 }