in6_cksum.c

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    1 /*      $NetBSD: in6_cksum.c,v 1.16 2003/08/07 16:33:24 agc Exp $       */
    2 /*      $KAME: in6_cksum.c,v 1.9 2000/09/09 15:33:31 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. Neither the name of the University nor the names of its contributors
   46  *    may be used to endorse or promote products derived from this software
   47  *    without specific prior written permission.
   48  *
   49  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   50  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   51  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   52  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   53  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   54  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   55  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   56  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   57  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   58  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   59  * SUCH DAMAGE.
   60  *
   61  *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
   62  */
   63 
   64 #include <sys/cdefs.h>
   65 __KERNEL_RCSID(0, "$NetBSD: in6_cksum.c,v 1.16 2003/08/07 16:33:24 agc Exp $");
   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 /*
   86  * m MUST contain a continuous IP6 header.
   87  * off is a offset where TCP/UDP/ICMP6 header starts.
   88  * len is a total length of a transport segment.
   89  * (e.g. TCP header + TCP payload)
   90  */
   91 
   92 int
   93 in6_cksum(m, nxt, off, len)
   94         struct mbuf *m;
   95         u_int8_t nxt;
   96         u_int32_t off, 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("in6_cksum: mbuf len (%d) < off+len (%d+%d)",
  123                         m->m_pkthdr.len, off, len);
  124         }
  125 
  126         /* Skip pseudo-header if nxt == 0. */
  127         if (nxt == 0)
  128                 goto skip_phdr;
  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         w = (u_int16_t *)&ip6->ip6_src;
  137         uph.ph.ph_len = htonl(len);
  138         uph.ph.ph_nxt = nxt;
  139 
  140         /* IPv6 source address */
  141         sum += w[0];
  142         if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
  143                 sum += w[1];
  144         sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
  145         sum += w[6]; sum += w[7];
  146         /* IPv6 destination address */
  147         sum += w[8];
  148         if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
  149                 sum += w[9];
  150         sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13];
  151         sum += w[14]; sum += w[15];
  152         /* Payload length and upper layer identifier */
  153         sum += uph.phs[0];  sum += uph.phs[1];
  154         sum += uph.phs[2];  sum += uph.phs[3];
  155 
  156  skip_phdr:
  157         /*
  158          * Secondly calculate a summary of the first mbuf excluding offset.
  159          */
  160         while (m != NULL && off > 0) {
  161                 if (m->m_len <= off)
  162                         off -= m->m_len;
  163                 else
  164                         break;
  165                 m = m->m_next;
  166         }
  167         w = (u_int16_t *)(mtod(m, u_char *) + off);
  168         mlen = m->m_len - off;
  169         if (len < mlen)
  170                 mlen = len;
  171         len -= mlen;
  172         /*
  173          * Force to even boundary.
  174          */
  175         if ((1 & (long) w) && (mlen > 0)) {
  176                 REDUCE;
  177                 sum <<= 8;
  178                 s_util.c[0] = *(u_char *)w;
  179                 w = (u_int16_t *)((char *)w + 1);
  180                 mlen--;
  181                 byte_swapped = 1;
  182         }
  183         /*
  184          * Unroll the loop to make overhead from
  185          * branches &c small.
  186          */
  187         while ((mlen -= 32) >= 0) {
  188                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  189                 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  190                 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
  191                 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
  192                 w += 16;
  193         }
  194         mlen += 32;
  195         while ((mlen -= 8) >= 0) {
  196                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  197                 w += 4;
  198         }
  199         mlen += 8;
  200         if (mlen == 0 && byte_swapped == 0)
  201                 goto next;
  202         REDUCE;
  203         while ((mlen -= 2) >= 0) {
  204                 sum += *w++;
  205         }
  206         if (byte_swapped) {
  207                 REDUCE;
  208                 sum <<= 8;
  209                 byte_swapped = 0;
  210                 if (mlen == -1) {
  211                         s_util.c[1] = *(char *)w;
  212                         sum += s_util.s;
  213                         mlen = 0;
  214                 } else
  215                         mlen = -1;
  216         } else if (mlen == -1)
  217                 s_util.c[0] = *(char *)w;
  218  next:
  219         m = m->m_next;
  220 
  221         /*
  222          * Lastly calculate a summary of the rest of mbufs.
  223          */
  224 
  225         for (;m && len; m = m->m_next) {
  226                 if (m->m_len == 0)
  227                         continue;
  228                 w = mtod(m, u_int16_t *);
  229                 if (mlen == -1) {
  230                         /*
  231                          * The first byte of this mbuf is the continuation
  232                          * of a word spanning between this mbuf and the
  233                          * last mbuf.
  234                          *
  235                          * s_util.c[0] is already saved when scanning previous
  236                          * mbuf.
  237                          */
  238                         s_util.c[1] = *(char *)w;
  239                         sum += s_util.s;
  240                         w = (u_int16_t *)((char *)w + 1);
  241                         mlen = m->m_len - 1;
  242                         len--;
  243                 } else
  244                         mlen = m->m_len;
  245                 if (len < mlen)
  246                         mlen = len;
  247                 len -= mlen;
  248                 /*
  249                  * Force to even boundary.
  250                  */
  251                 if ((1 & (long) w) && (mlen > 0)) {
  252                         REDUCE;
  253                         sum <<= 8;
  254                         s_util.c[0] = *(u_char *)w;
  255                         w = (u_int16_t *)((char *)w + 1);
  256                         mlen--;
  257                         byte_swapped = 1;
  258                 }
  259                 /*
  260                  * Unroll the loop to make overhead from
  261                  * branches &c small.
  262                  */
  263                 while ((mlen -= 32) >= 0) {
  264                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  265                         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  266                         sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
  267                         sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
  268                         w += 16;
  269                 }
  270                 mlen += 32;
  271                 while ((mlen -= 8) >= 0) {
  272                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  273                         w += 4;
  274                 }
  275                 mlen += 8;
  276                 if (mlen == 0 && byte_swapped == 0)
  277                         continue;
  278                 REDUCE;
  279                 while ((mlen -= 2) >= 0) {
  280                         sum += *w++;
  281                 }
  282                 if (byte_swapped) {
  283                         REDUCE;
  284                         sum <<= 8;
  285                         byte_swapped = 0;
  286                         if (mlen == -1) {
  287                                 s_util.c[1] = *(char *)w;
  288                                 sum += s_util.s;
  289                                 mlen = 0;
  290                         } else
  291                                 mlen = -1;
  292                 } else if (mlen == -1)
  293                         s_util.c[0] = *(char *)w;
  294         }
  295         if (len)
  296                 panic("in6_cksum: out of data");
  297         if (mlen == -1) {
  298                 /* The last mbuf has odd # of bytes. Follow the
  299                    standard (the odd byte may be shifted left by 8 bits
  300                    or not as determined by endian-ness of the machine) */
  301                 s_util.c[1] = 0;
  302                 sum += s_util.s;
  303         }
  304         REDUCE;
  305         return (~sum & 0xffff);
  306 }
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FreeBSD/Linux Kernel Cross Reference sys/netinet6/in6_cksum.c

FreeBSD/Linux Kernel Cross Reference
sys/netinet6/in6_cksum.c
