in6_cksum.c

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    1 /*-
    2  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. Neither the name of the project nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      $KAME: in6_cksum.c,v 1.10 2000/12/03 00:53:59 itojun Exp $
   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  * 4. Neither the name of the University nor the names of its contributors
   45  *    may be used to endorse or promote products derived from this software
   46  *    without specific prior written permission.
   47  *
   48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   58  * SUCH DAMAGE.
   59  *
   60  *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
   61  */
   62 
   63 #include <sys/cdefs.h>
   64 __FBSDID("$FreeBSD$");
   65 
   66 #include <sys/param.h>
   67 #include <sys/mbuf.h>
   68 #include <sys/systm.h>
   69 #include <netinet/in.h>
   70 #include <netinet/ip6.h>
   71 #include <netinet6/scope6_var.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 an 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         struct in6_addr in6;
  104         union {
  105                 u_int16_t phs[4];
  106                 struct {
  107                         u_int32_t       ph_len;
  108                         u_int8_t        ph_zero[3];
  109                         u_int8_t        ph_nxt;
  110                 } ph __packed;
  111         } uph;
  112         union {
  113                 u_int8_t        c[2];
  114                 u_int16_t       s;
  115         } s_util;
  116         union {
  117                 u_int16_t s[2];
  118                 u_int32_t l;
  119         } l_util;
  120 
  121         /* sanity check */
  122         if (m->m_pkthdr.len < off + len) {
  123                 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)",
  124                         m->m_pkthdr.len, off, len);
  125         }
  126 
  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         uph.ph.ph_len = htonl(len);
  134         uph.ph.ph_nxt = nxt;
  135 
  136         /*
  137          * IPv6 source address.
  138          * XXX: we'd like to avoid copying the address, but we can't due to
  139          * the possibly embedded scope zone ID.
  140          */
  141         in6 = ip6->ip6_src;
  142         in6_clearscope(&in6);
  143         w = (u_int16_t *)&in6;
  144         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  145         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  146 
  147         /* IPv6 destination address */
  148         in6 = ip6->ip6_dst;
  149         in6_clearscope(&in6);
  150         w = (u_int16_t *)&in6;
  151         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  152         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  153 
  154         /* Payload length and upper layer identifier */
  155         sum += uph.phs[0];  sum += uph.phs[1];
  156         sum += uph.phs[2];  sum += uph.phs[3];
  157 
  158         /*
  159          * Secondly calculate a summary of the first mbuf excluding offset.
  160          */
  161         while (m != NULL && off > 0) {
  162                 if (m->m_len <= off)
  163                         off -= m->m_len;
  164                 else
  165                         break;
  166                 m = m->m_next;
  167         }
  168         w = (u_int16_t *)(mtod(m, u_char *) + off);
  169         mlen = m->m_len - off;
  170         if (len < mlen)
  171                 mlen = len;
  172         len -= mlen;
  173         /*
  174          * Force to even boundary.
  175          */
  176         if ((1 & (long) w) && (mlen > 0)) {
  177                 REDUCE;
  178                 sum <<= 8;
  179                 s_util.c[0] = *(u_char *)w;
  180                 w = (u_int16_t *)((char *)w + 1);
  181                 mlen--;
  182                 byte_swapped = 1;
  183         }
  184         /*
  185          * Unroll the loop to make overhead from
  186          * branches &c small.
  187          */
  188         while ((mlen -= 32) >= 0) {
  189                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  190                 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  191                 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
  192                 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
  193                 w += 16;
  194         }
  195         mlen += 32;
  196         while ((mlen -= 8) >= 0) {
  197                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  198                 w += 4;
  199         }
  200         mlen += 8;
  201         if (mlen == 0 && byte_swapped == 0)
  202                 goto next;
  203         REDUCE;
  204         while ((mlen -= 2) >= 0) {
  205                 sum += *w++;
  206         }
  207         if (byte_swapped) {
  208                 REDUCE;
  209                 sum <<= 8;
  210                 byte_swapped = 0;
  211                 if (mlen == -1) {
  212                         s_util.c[1] = *(char *)w;
  213                         sum += s_util.s;
  214                         mlen = 0;
  215                 } else
  216                         mlen = -1;
  217         } else if (mlen == -1)
  218                 s_util.c[0] = *(char *)w;
  219  next:
  220         m = m->m_next;
  221 
  222         /*
  223          * Lastly calculate a summary of the rest of mbufs.
  224          */
  225 
  226         for (;m && len; m = m->m_next) {
  227                 if (m->m_len == 0)
  228                         continue;
  229                 w = mtod(m, u_int16_t *);
  230                 if (mlen == -1) {
  231                         /*
  232                          * The first byte of this mbuf is the continuation
  233                          * of a word spanning between this mbuf and the
  234                          * last mbuf.
  235                          *
  236                          * s_util.c[0] is already saved when scanning previous
  237                          * mbuf.
  238                          */
  239                         s_util.c[1] = *(char *)w;
  240                         sum += s_util.s;
  241                         w = (u_int16_t *)((char *)w + 1);
  242                         mlen = m->m_len - 1;
  243                         len--;
  244                 } else
  245                         mlen = m->m_len;
  246                 if (len < mlen)
  247                         mlen = len;
  248                 len -= mlen;
  249                 /*
  250                  * Force to even boundary.
  251                  */
  252                 if ((1 & (long) w) && (mlen > 0)) {
  253                         REDUCE;
  254                         sum <<= 8;
  255                         s_util.c[0] = *(u_char *)w;
  256                         w = (u_int16_t *)((char *)w + 1);
  257                         mlen--;
  258                         byte_swapped = 1;
  259                 }
  260                 /*
  261                  * Unroll the loop to make overhead from
  262                  * branches &c small.
  263                  */
  264                 while ((mlen -= 32) >= 0) {
  265                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  266                         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  267                         sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
  268                         sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
  269                         w += 16;
  270                 }
  271                 mlen += 32;
  272                 while ((mlen -= 8) >= 0) {
  273                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  274                         w += 4;
  275                 }
  276                 mlen += 8;
  277                 if (mlen == 0 && byte_swapped == 0)
  278                         continue;
  279                 REDUCE;
  280                 while ((mlen -= 2) >= 0) {
  281                         sum += *w++;
  282                 }
  283                 if (byte_swapped) {
  284                         REDUCE;
  285                         sum <<= 8;
  286                         byte_swapped = 0;
  287                         if (mlen == -1) {
  288                                 s_util.c[1] = *(char *)w;
  289                                 sum += s_util.s;
  290                                 mlen = 0;
  291                         } else
  292                                 mlen = -1;
  293                 } else if (mlen == -1)
  294                         s_util.c[0] = *(char *)w;
  295         }
  296         if (len)
  297                 panic("in6_cksum: out of data");
  298         if (mlen == -1) {
  299                 /* The last mbuf has odd # of bytes. Follow the
  300                    standard (the odd byte may be shifted left by 8 bits
  301                    or not as determined by endian-ness of the machine) */
  302                 s_util.c[1] = 0;
  303                 sum += s_util.s;
  304         }
  305         REDUCE;
  306         return (~sum & 0xffff);
  307 }
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FreeBSD/Linux Kernel Cross Reference sys/netinet6/in6_cksum.c

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