bsd/netns/ns_cksum.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Copyright (c) 1982, 1992, 1993
  24  *      The Regents of the University of California.  All rights reserved.
  25  *
  26  * Redistribution and use in source and binary forms, with or without
  27  * modification, are permitted provided that the following conditions
  28  * are met:
  29  * 1. Redistributions of source code must retain the above copyright
  30  *    notice, this list of conditions and the following disclaimer.
  31  * 2. Redistributions in binary form must reproduce the above copyright
  32  *    notice, this list of conditions and the following disclaimer in the
  33  *    documentation and/or other materials provided with the distribution.
  34  * 3. All advertising materials mentioning features or use of this software
  35  *    must display the following acknowledgement:
  36  *      This product includes software developed by the University of
  37  *      California, Berkeley and its contributors.
  38  * 4. Neither the name of the University nor the names of its contributors
  39  *    may be used to endorse or promote products derived from this software
  40  *    without specific prior written permission.
  41  *
  42  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  43  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  44  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  45  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  46  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  47  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  48  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  49  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  50  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  51  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  52  * SUCH DAMAGE.
  53  *
  54  *      @(#)ns_cksum.c  8.1 (Berkeley) 6/10/93
  55  */
  56
  57 #include <sys/param.h>
  58 #include <sys/mbuf.h>
  59
  60 /*
  61  * Checksum routine for Network Systems Protocol Packets (Big-Endian).
  62  *
  63  * This routine is very heavily used in the network
  64  * code and should be modified for each CPU to be as fast as possible.
  65  */
  66
  67 #define ADDCARRY(x)  { if ((x) > 65535) (x) -= 65535; }
  68 #define FOLD(x) {l_util.l = (x); (x) = l_util.s[0] + l_util.s[1]; ADDCARRY(x);}
  69
  70 u_short
  71 ns_cksum(m, len)
  72         register struct mbuf *m;
  73         register int len;
  74 {
  75         register u_short *w;
  76         register int sum = 0;
  77         register int mlen = 0;
  78         register int sum2;
  79
  80         union {
  81                 u_short s[2];
  82                 long    l;
  83         } l_util;
  84
  85         for (;m && len; m = m->m_next) {
  86                 if (m->m_len == 0)
  87                         continue;
  88                 /*
  89                  * Each trip around loop adds in
  90                  * word from one mbuf segment.
  91                  */
  92                 w = mtod(m, u_short *);
  93                 if (mlen == -1) {
  94                         /*
  95                          * There is a byte left from the last segment;
  96                          * ones-complement add it into the checksum.
  97                          */
  98 #if BYTE_ORDER == BIG_ENDIAN
  99                         sum  += *(u_char *)w;
 100 #else
 101                         sum  += *(u_char *)w << 8;
 102 #endif
 103                         sum += sum;
 104                         w = (u_short *)(1 + (char *)w);
 105                         mlen = m->m_len - 1;
 106                         len--;
 107                         FOLD(sum);
 108                 } else
 109                         mlen = m->m_len;
 110                 if (len < mlen)
 111                         mlen = len;
 112                 len -= mlen;
 113                 /*
 114                  * We can do a 16 bit ones complement sum using
 115                  * 32 bit arithmetic registers for adding,
 116                  * with carries from the low added
 117                  * into the high (by normal carry-chaining)
 118                  * so long as we fold back before 16 carries have occured.
 119                  */
 120                 if (1 & (int) w)
 121                         goto uuuuglyy;
 122 #ifndef TINY
 123 /* -DTINY reduces the size from 1250 to 550, but slows it down by 22% */
 124                 while ((mlen -= 32) >= 0) {
 125                         sum += w[0]; sum += sum; sum += w[1]; sum += sum;
 126                         sum += w[2]; sum += sum; sum += w[3]; sum += sum;
 127                         sum += w[4]; sum += sum; sum += w[5]; sum += sum;
 128                         sum += w[6]; sum += sum; sum += w[7]; sum += sum;
 129                         FOLD(sum);
 130                         sum += w[8]; sum += sum; sum += w[9]; sum += sum;
 131                         sum += w[10]; sum += sum; sum += w[11]; sum += sum;
 132                         sum += w[12]; sum += sum; sum += w[13]; sum += sum;
 133                         sum += w[14]; sum += sum; sum += w[15]; sum += sum;
 134                         FOLD(sum);
 135                         w += 16;
 136                 }
 137                 mlen += 32;
 138 #endif
 139                 while ((mlen -= 8) >= 0) {
 140                         sum += w[0]; sum += sum; sum += w[1]; sum += sum;
 141                         sum += w[2]; sum += sum; sum += w[3]; sum += sum;
 142                         FOLD(sum);
 143                         w += 4;
 144                 }
 145                 mlen += 8;
 146                 while ((mlen -= 2) >= 0) {
 147                         sum += *w++; sum += sum;
 148                 }
 149                 goto commoncase;
 150 uuuuglyy:
 151 #if BYTE_ORDER == BIG_ENDIAN
 152 #define ww(n) (((u_char *)w)[n + n + 1])
 153 #define vv(n) (((u_char *)w)[n + n])
 154 #else
 155 #if BYTE_ORDER == LITTLE_ENDIAN
 156 #define vv(n) (((u_char *)w)[n + n + 1])
 157 #define ww(n) (((u_char *)w)[n + n])
 158 #endif
 159 #endif
 160                 sum2 = 0;
 161 #ifndef TINY
 162                 while ((mlen -= 32) >= 0) {
 163                     sum += ww(0); sum += sum; sum += ww(1); sum += sum;
 164                     sum += ww(2); sum += sum; sum += ww(3); sum += sum;
 165                     sum += ww(4); sum += sum; sum += ww(5); sum += sum;
 166                     sum += ww(6); sum += sum; sum += ww(7); sum += sum;
 167                     FOLD(sum);
 168                     sum += ww(8); sum += sum; sum += ww(9); sum += sum;
 169                     sum += ww(10); sum += sum; sum += ww(11); sum += sum;
 170                     sum += ww(12); sum += sum; sum += ww(13); sum += sum;
 171                     sum += ww(14); sum += sum; sum += ww(15); sum += sum;
 172                     FOLD(sum);
 173                     sum2 += vv(0); sum2 += sum2; sum2 += vv(1); sum2 += sum2;
 174                     sum2 += vv(2); sum2 += sum2; sum2 += vv(3); sum2 += sum2;
 175                     sum2 += vv(4); sum2 += sum2; sum2 += vv(5); sum2 += sum2;
 176                     sum2 += vv(6); sum2 += sum2; sum2 += vv(7); sum2 += sum2;
 177                     FOLD(sum2);
 178                     sum2 += vv(8); sum2 += sum2; sum2 += vv(9); sum2 += sum2;
 179                     sum2 += vv(10); sum2 += sum2; sum2 += vv(11); sum2 += sum2;
 180                     sum2 += vv(12); sum2 += sum2; sum2 += vv(13); sum2 += sum2;
 181                     sum2 += vv(14); sum2 += sum2; sum2 += vv(15); sum2 += sum2;
 182                     FOLD(sum2);
 183                     w += 16;
 184                 }
 185                 mlen += 32;
 186 #endif
 187                 while ((mlen -= 8) >= 0) {
 188                     sum += ww(0); sum += sum; sum += ww(1); sum += sum;
 189                     sum += ww(2); sum += sum; sum += ww(3); sum += sum;
 190                     FOLD(sum);
 191                     sum2 += vv(0); sum2 += sum2; sum2 += vv(1); sum2 += sum2;
 192                     sum2 += vv(2); sum2 += sum2; sum2 += vv(3); sum2 += sum2;
 193                     FOLD(sum2);
 194                     w += 4;
 195                 }
 196                 mlen += 8;
 197                 while ((mlen -= 2) >= 0) {
 198                         sum += ww(0); sum += sum;
 199                         sum2 += vv(0); sum2 += sum2;
 200                         w++;
 201                 }
 202                 sum += (sum2 << 8);
 203 commoncase:
 204                 if (mlen == -1) {
 205 #if BYTE_ORDER == BIG_ENDIAN
 206                         sum += *(u_char *)w << 8;
 207 #else
 208                         sum += *(u_char *)w;
 209 #endif
 210                 }
 211                 FOLD(sum);
 212         }
 213         if (mlen == -1) {
 214                 /* We had an odd number of bytes to sum; assume a garbage
 215                    byte of zero and clean up */
 216                 sum += sum;
 217                 FOLD(sum);
 218         }
 219         /*
 220          * sum has already been kept to low sixteen bits.
 221          * just examine result and exit.
 222          */
 223         if(sum==0xffff) sum = 0;
 224         return (sum);
 225 }