in4_cksum.c

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    1 /*      $NetBSD: in4_cksum.c,v 1.12 2005/12/11 12:24:57 christos Exp $  */
    2 
    3 /*
    4  * Copyright (C) 1999 WIDE Project.
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 3. Neither the name of the project nor the names of its contributors
   16  *    may be used to endorse or promote products derived from this software
   17  *    without specific prior written permission.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   29  * SUCH DAMAGE.
   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  * 3. 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 __KERNEL_RCSID(0, "$NetBSD: in4_cksum.c,v 1.12 2005/12/11 12:24:57 christos Exp $");
   65 
   66 #include <sys/param.h>
   67 #include <sys/mbuf.h>
   68 #include <sys/systm.h>
   69 #include <sys/socket.h>
   70 #include <net/route.h>
   71 #include <netinet/in.h>
   72 #include <netinet/in_systm.h>
   73 #include <netinet/ip.h>
   74 #include <netinet/ip_var.h>
   75 
   76 /*
   77  * Checksum routine for Internet Protocol family headers (Portable Version).
   78  * This is only for IPv4 pseudo header checksum.
   79  * No need to clear non-pseudo-header fields in IPv4 header.
   80  * len is for actual payload size, and does not include IPv4 header and
   81  * skipped header chain (off + len should be equal to the whole packet).
   82  *
   83  * This routine is very heavily used in the network
   84  * code and should be modified for each CPU to be as fast as possible.
   85  */
   86 
   87 #define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
   88 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
   89 
   90 int
   91 in4_cksum(struct mbuf *m, u_int8_t nxt, int off, int len)
   92 {
   93         u_int16_t *w;
   94         int sum = 0;
   95         int mlen = 0;
   96         int byte_swapped = 0;
   97         union {
   98                 struct ipovly ipov;
   99                 u_int16_t w[10];
  100         } u;
  101         union {
  102                 u_int8_t  c[2];
  103                 u_int16_t s;
  104         } s_util;
  105         union {
  106                 u_int16_t s[2];
  107                 u_int32_t l;
  108         } l_util;
  109 
  110         if (nxt != 0) {
  111                 /* pseudo header */
  112                 if (off < sizeof(struct ipovly))
  113                         panic("in4_cksum: offset too short");
  114                 if (m->m_len < sizeof(struct ip))
  115                         panic("in4_cksum: bad mbuf chain");
  116                 bzero(&u.ipov, sizeof(u.ipov));
  117                 u.ipov.ih_len = htons(len);
  118                 u.ipov.ih_pr = nxt;
  119                 u.ipov.ih_src = mtod(m, struct ip *)->ip_src;
  120                 u.ipov.ih_dst = mtod(m, struct ip *)->ip_dst;
  121                 w = u.w;
  122                 /* assumes sizeof(ipov) == 20 */
  123                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; sum += w[4];
  124                 sum += w[5]; sum += w[6]; sum += w[7]; sum += w[8]; sum += w[9];
  125         }
  126 
  127         /* skip unnecessary part */
  128         while (m && off > 0) {
  129                 if (m->m_len > off)
  130                         break;
  131                 off -= m->m_len;
  132                 m = m->m_next;
  133         }
  134 
  135         for (;m && len; m = m->m_next) {
  136                 if (m->m_len == 0)
  137                         continue;
  138                 w = (u_int16_t *)(mtod(m, caddr_t) + off);
  139                 if (mlen == -1) {
  140                         /*
  141                          * The first byte of this mbuf is the continuation
  142                          * of a word spanning between this mbuf and the
  143                          * last mbuf.
  144                          *
  145                          * s_util.c[0] is already saved when scanning previous
  146                          * mbuf.
  147                          */
  148                         s_util.c[1] = *(u_int8_t *)w;
  149                         sum += s_util.s;
  150                         w = (u_int16_t *)((u_int8_t *)w + 1);
  151                         mlen = m->m_len - off - 1;
  152                         len--;
  153                 } else
  154                         mlen = m->m_len - off;
  155                 off = 0;
  156                 if (len < mlen)
  157                         mlen = len;
  158                 len -= mlen;
  159                 /*
  160                  * Force to even boundary.
  161                  */
  162                 if ((1 & (long) w) && (mlen > 0)) {
  163                         REDUCE;
  164                         sum <<= 8;
  165                         s_util.c[0] = *(u_int8_t *)w;
  166                         w = (u_int16_t *)((int8_t *)w + 1);
  167                         mlen--;
  168                         byte_swapped = 1;
  169                 }
  170                 /*
  171                  * Unroll the loop to make overhead from
  172                  * branches &c small.
  173                  */
  174                 while ((mlen -= 32) >= 0) {
  175                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  176                         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  177                         sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
  178                         sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
  179                         w += 16;
  180                 }
  181                 mlen += 32;
  182                 while ((mlen -= 8) >= 0) {
  183                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  184                         w += 4;
  185                 }
  186                 mlen += 8;
  187                 if (mlen == 0 && byte_swapped == 0)
  188                         continue;
  189                 REDUCE;
  190                 while ((mlen -= 2) >= 0) {
  191                         sum += *w++;
  192                 }
  193                 if (byte_swapped) {
  194                         REDUCE;
  195                         sum <<= 8;
  196                         byte_swapped = 0;
  197                         if (mlen == -1) {
  198                                 s_util.c[1] = *(u_int8_t *)w;
  199                                 sum += s_util.s;
  200                                 mlen = 0;
  201                         } else
  202                                 mlen = -1;
  203                 } else if (mlen == -1)
  204                         s_util.c[0] = *(u_int8_t *)w;
  205         }
  206         if (len)
  207                 printf("cksum4: out of data\n");
  208         if (mlen == -1) {
  209                 /* The last mbuf has odd # of bytes. Follow the
  210                    standard (the odd byte may be shifted left by 8 bits
  211                    or not as determined by endian-ness of the machine) */
  212                 s_util.c[1] = 0;
  213                 sum += s_util.s;
  214         }
  215         REDUCE;
  216         return (~sum & 0xffff);
  217 }

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FreeBSD/Linux Kernel Cross Reference sys/netinet/in4_cksum.c

FreeBSD/Linux Kernel Cross Reference
sys/netinet/in4_cksum.c