workbench/network/stacks/AROSTCP/bsdsocket/netinet/in_cksum.c

   1 /*
   2  * Copyright (C) 1993 AmiTCP/IP Group, <amitcp-group@hut.fi>
   3  *                    Helsinki University of Technology, Finland.
   4  *                    All rights reserved.
   5  * Copyright (C) 2005 Neil Cafferkey
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  19  * MA 02111-1307, USA.
  20  *
  21  */
  22
  23 /*
  24  * Copyright (c) 1988 Regents of the University of California.
  25  * All rights reserved.
  26  *
  27  * Redistribution and use in source and binary forms, with or without
  28  * modification, are permitted provided that the following conditions
  29  * are met:
  30  * 1. Redistributions of source code must retain the above copyright
  31  *    notice, this list of conditions and the following disclaimer.
  32  * 2. Redistributions in binary form must reproduce the above copyright
  33  *    notice, this list of conditions and the following disclaimer in the
  34  *    documentation and/or other materials provided with the distribution.
  35  * 3. All advertising materials mentioning features or use of this software
  36  *    must display the following acknowledgement:
  37  *      This product includes software developed by the University of
  38  *      California, Berkeley and its contributors.
  39  * 4. Neither the name of the University nor the names of its contributors
  40  *    may be used to endorse or promote products derived from this software
  41  *    without specific prior written permission.
  42  *
  43  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  44  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  45  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  46  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  47  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  48  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  49  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  50  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  51  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  52  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  53  * SUCH DAMAGE.
  54  *
  55  *      @(#)in_cksum.c  7.3 (Berkeley) 6/28/90
  56  */
  57
  58 #include <conf.h>
  59
  60 #include <sys/param.h>
  61 #include <sys/systm.h>
  62 #include <sys/malloc.h>
  63 #include <sys/mbuf.h>
  64
  65 #include <netinet/in_cksum_protos.h>
  66
  67 /*
  68  * Checksum routine for Internet Protocol family headers (Portable Version).
  69  *
  70  * This routine is very heavily used in the network
  71  * code and should be modified for each CPU to be as fast as possible.
  72  */
  73
  74 #define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
  75 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
  76
  77 int
  78 in_cksum(m, len)
  79         register struct mbuf *m;
  80         register int len;
  81 {
  82         register u_short *w;
  83         register int sum = 0;
  84         register int mlen = 0;
  85         int byte_swapped = 0;
  86
  87         union {
  88                 char    c[2];
  89                 u_short s;
  90         } s_util;
  91         union {
  92                 u_short s[2];
  93                 long    l;
  94         } l_util;
  95
  96         for (;m && len; m = m->m_next) {
  97                 if (m->m_len == 0)
  98                         continue;
  99                 w = mtod(m, u_short *);
 100                 if (mlen == -1) {
 101                         /*
 102                          * The first byte of this mbuf is the continuation
 103                          * of a word spanning between this mbuf and the
 104                          * last mbuf.
 105                          *
 106                          * s_util.c[0] is already saved when scanning previous
 107                          * mbuf.
 108                          */
 109                         s_util.c[1] = *(char *)w;
 110                         sum += s_util.s;
 111                         w = (u_short *)((char *)w + 1);
 112                         mlen = m->m_len - 1;
 113                         len--;
 114                 } else
 115                         mlen = m->m_len;
 116                 if (len < mlen)
 117                         mlen = len;
 118                 len -= mlen;
 119                 /*
 120                  * Force to even boundary.
 121                  */
 122                 if ((1 & (long) w) && (mlen > 0)) {
 123                         REDUCE;
 124                         sum <<= 8;
 125                         s_util.c[0] = *(u_char *)w;
 126                         w = (u_short *)((char *)w + 1);
 127                         mlen--;
 128                         byte_swapped = 1;
 129                 }
 130                 /*
 131                  * Unroll the loop to make overhead from
 132                  * branches &c small.
 133                  */
 134                 while ((mlen -= 32) >= 0) {
 135                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 136                         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
 137                         sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
 138                         sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
 139                         w += 16;
 140                 }
 141                 mlen += 32;
 142                 while ((mlen -= 8) >= 0) {
 143                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
 144                         w += 4;
 145                 }
 146                 mlen += 8;
 147                 if (mlen == 0 && byte_swapped == 0)
 148                         continue;
 149                 REDUCE;
 150                 while ((mlen -= 2) >= 0) {
 151                         sum += *w++;
 152                 }
 153                 if (byte_swapped) {
 154                         REDUCE;
 155                         sum <<= 8;
 156                         byte_swapped = 0;
 157                         if (mlen == -1) {
 158                                 s_util.c[1] = *(char *)w;
 159                                 sum += s_util.s;
 160                                 mlen = 0;
 161                         } else
 162                                 mlen = -1;
 163                 } else if (mlen == -1)
 164                         s_util.c[0] = *(char *)w;
 165         }
 166         if (len)
 167                 printf("cksum: out of data\n");
 168         if (mlen == -1) {
 169                 /* The last mbuf has odd # of bytes. Follow the
 170                    standard (the odd byte may be shifted left by 8 bits
 171                    or not as determined by endian-ness of the machine) */
 172                 s_util.c[1] = 0;
 173                 sum += s_util.s;
 174         }
 175         REDUCE;
 176         return (~sum & 0xffff);
 177 }