in6_cksum.c

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    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 #if 0
   98         int srcifid = 0, dstifid = 0;
   99 #endif
  100         struct ip6_hdr *ip6;
  101         union {
  102                 u_int16_t phs[4];
  103                 struct {
  104                         u_int32_t       ph_len;
  105                         u_int8_t        ph_zero[3];
  106                         u_int8_t        ph_nxt;
  107                 } ph __attribute__((__packed__));
  108         } uph;
  109         union {
  110                 u_int8_t        c[2];
  111                 u_int16_t       s;
  112         } s_util;
  113         union {
  114                 u_int16_t s[2];
  115                 u_int32_t l;
  116         } l_util;
  117 
  118         /* sanity check */
  119         if (m->m_pkthdr.len < off + len) {
  120                 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)",
  121                         m->m_pkthdr.len, off, len);
  122         }
  123 
  124         bzero(&uph, sizeof(uph));
  125 
  126         /*
  127          * First create IP6 pseudo header and calculate a summary.
  128          */
  129         ip6 = mtod(m, struct ip6_hdr *);
  130 #if 0
  131         if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src)) {
  132                 srcifid = ip6->ip6_src.s6_addr16[1];
  133                 ip6->ip6_src.s6_addr16[1] = 0;
  134         }
  135         if (IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst)) {
  136                 dstifid = ip6->ip6_dst.s6_addr16[1];
  137                 ip6->ip6_dst.s6_addr16[1] = 0;
  138         }
  139 #endif
  140         w = (u_int16_t *)&ip6->ip6_src;
  141         uph.ph.ph_len = htonl(len);
  142         uph.ph.ph_nxt = nxt;
  143 
  144         /* IPv6 source address */
  145         sum += w[0];
  146         if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_src))
  147                 sum += w[1];
  148         sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5];
  149         sum += w[6]; sum += w[7];
  150         /* IPv6 destination address */
  151         sum += w[8];
  152         if (!IN6_IS_SCOPE_LINKLOCAL(&ip6->ip6_dst))
  153                 sum += w[9];
  154         sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13];
  155         sum += w[14]; sum += w[15];
  156         /* Payload length and upper layer identifier */
  157         sum += uph.phs[0];  sum += uph.phs[1];
  158         sum += uph.phs[2];  sum += uph.phs[3];
  159 
  160 #if 0
  161         if (srcifid)
  162                 ip6->ip6_src.s6_addr16[1] = srcifid;
  163         if (dstifid)
  164                 ip6->ip6_dst.s6_addr16[1] = dstifid;
  165 #endif
  166         /*
  167          * Secondly calculate a summary of the first mbuf excluding offset.
  168          */
  169         while (m != NULL && off > 0) {
  170                 if (m->m_len <= off)
  171                         off -= m->m_len;
  172                 else
  173                         break;
  174                 m = m->m_next;
  175         }
  176         w = (u_int16_t *)(mtod(m, u_char *) + off);
  177         mlen = m->m_len - off;
  178         if (len < mlen)
  179                 mlen = len;
  180         len -= mlen;
  181         /*
  182          * Force to even boundary.
  183          */
  184         if ((1 & (long) w) && (mlen > 0)) {
  185                 REDUCE;
  186                 sum <<= 8;
  187                 s_util.c[0] = *(u_char *)w;
  188                 w = (u_int16_t *)((char *)w + 1);
  189                 mlen--;
  190                 byte_swapped = 1;
  191         }
  192         /*
  193          * Unroll the loop to make overhead from
  194          * branches &c small.
  195          */
  196         while ((mlen -= 32) >= 0) {
  197                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  198                 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  199                 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
  200                 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
  201                 w += 16;
  202         }
  203         mlen += 32;
  204         while ((mlen -= 8) >= 0) {
  205                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  206                 w += 4;
  207         }
  208         mlen += 8;
  209         if (mlen == 0 && byte_swapped == 0)
  210                 goto next;
  211         REDUCE;
  212         while ((mlen -= 2) >= 0) {
  213                 sum += *w++;
  214         }
  215         if (byte_swapped) {
  216                 REDUCE;
  217                 sum <<= 8;
  218                 byte_swapped = 0;
  219                 if (mlen == -1) {
  220                         s_util.c[1] = *(char *)w;
  221                         sum += s_util.s;
  222                         mlen = 0;
  223                 } else
  224                         mlen = -1;
  225         } else if (mlen == -1)
  226                 s_util.c[0] = *(char *)w;
  227 next:
  228         m = m->m_next;
  229 
  230         /*
  231          * Lastly calculate a summary of the rest of mbufs.
  232          */
  233 
  234         for (;m && len; m = m->m_next) {
  235                 if (m->m_len == 0)
  236                         continue;
  237                 w = mtod(m, u_int16_t *);
  238                 if (mlen == -1) {
  239                         /*
  240                          * The first byte of this mbuf is the continuation
  241                          * of a word spanning between this mbuf and the
  242                          * last mbuf.
  243                          *
  244                          * s_util.c[0] is already saved when scanning previous
  245                          * mbuf.
  246                          */
  247                         s_util.c[1] = *(char *)w;
  248                         sum += s_util.s;
  249                         w = (u_int16_t *)((char *)w + 1);
  250                         mlen = m->m_len - 1;
  251                         len--;
  252                 } else
  253                         mlen = m->m_len;
  254                 if (len < mlen)
  255                         mlen = len;
  256                 len -= mlen;
  257                 /*
  258                  * Force to even boundary.
  259                  */
  260                 if ((1 & (long) w) && (mlen > 0)) {
  261                         REDUCE;
  262                         sum <<= 8;
  263                         s_util.c[0] = *(u_char *)w;
  264                         w = (u_int16_t *)((char *)w + 1);
  265                         mlen--;
  266                         byte_swapped = 1;
  267                 }
  268                 /*
  269                  * Unroll the loop to make overhead from
  270                  * branches &c small.
  271                  */
  272                 while ((mlen -= 32) >= 0) {
  273                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  274                         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  275                         sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
  276                         sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
  277                         w += 16;
  278                 }
  279                 mlen += 32;
  280                 while ((mlen -= 8) >= 0) {
  281                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  282                         w += 4;
  283                 }
  284                 mlen += 8;
  285                 if (mlen == 0 && byte_swapped == 0)
  286                         continue;
  287                 REDUCE;
  288                 while ((mlen -= 2) >= 0) {
  289                         sum += *w++;
  290                 }
  291                 if (byte_swapped) {
  292                         REDUCE;
  293                         sum <<= 8;
  294                         byte_swapped = 0;
  295                         if (mlen == -1) {
  296                                 s_util.c[1] = *(char *)w;
  297                                 sum += s_util.s;
  298                                 mlen = 0;
  299                         } else
  300                                 mlen = -1;
  301                 } else if (mlen == -1)
  302                         s_util.c[0] = *(char *)w;
  303         }
  304         if (len)
  305                 panic("in6_cksum: out of data");
  306         if (mlen == -1) {
  307                 /* The last mbuf has odd # of bytes. Follow the
  308                    standard (the odd byte may be shifted left by 8 bits
  309                    or not as determined by endian-ness of the machine) */
  310                 s_util.c[1] = 0;
  311                 sum += s_util.s;
  312         }
  313         REDUCE;
  314         return (~sum & 0xffff);
  315 }
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FreeBSD/Linux Kernel Cross Reference sys/netinet6/in6_cksum.c

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