149 lines
4.3 KiB
C
149 lines
4.3 KiB
C
/*
|
|
* Copyright (c) 1988 Regents of the University of California.
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the University of
|
|
* California, Berkeley and its contributors.
|
|
* 4. Neither the name of the University nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* @(#)in_cksum.c 7.3 (Berkeley) 6/28/90
|
|
*/
|
|
|
|
#include "../h/types.h"
|
|
#include "../h/mbuf.h"
|
|
|
|
/*
|
|
* Checksum routine for Internet Protocol family headers (Portable Version).
|
|
*
|
|
* This routine is very heavily used in the network
|
|
* code and should be modified for each CPU to be as fast as possible.
|
|
*/
|
|
|
|
#define ADDCARRY(x) (x > 65535 ? x -= 65535 : x)
|
|
#define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
|
|
|
|
in_cksum_c(m, len)
|
|
register struct mbuf *m;
|
|
register int len;
|
|
{
|
|
register u_short *w;
|
|
register int sum = 0;
|
|
register int mlen = 0;
|
|
int byte_swapped = 0;
|
|
|
|
union {
|
|
char c[2];
|
|
u_short s;
|
|
} s_util;
|
|
union {
|
|
u_short s[2];
|
|
long l;
|
|
} l_util;
|
|
|
|
for (;m && len; m = m->m_next) {
|
|
if (m->m_len == 0)
|
|
continue;
|
|
w = mtod(m, u_short *);
|
|
if (mlen == -1) {
|
|
/*
|
|
* The first byte of this mbuf is the continuation
|
|
* of a word spanning between this mbuf and the
|
|
* last mbuf.
|
|
*
|
|
* s_util.c[0] is already saved when scanning previous
|
|
* mbuf.
|
|
*/
|
|
s_util.c[1] = *(char *)w;
|
|
sum += s_util.s;
|
|
w = (u_short *)((char *)w + 1);
|
|
mlen = m->m_len - 1;
|
|
len--;
|
|
} else
|
|
mlen = m->m_len;
|
|
if (len < mlen)
|
|
mlen = len;
|
|
len -= mlen;
|
|
/*
|
|
* Force to even boundary.
|
|
*/
|
|
if ((1 & (int) w) && (mlen > 0)) {
|
|
REDUCE;
|
|
sum <<= 8;
|
|
s_util.c[0] = *(u_char *)w;
|
|
w = (u_short *)((char *)w + 1);
|
|
mlen--;
|
|
byte_swapped = 1;
|
|
}
|
|
/*
|
|
* Unroll the loop to make overhead from
|
|
* branches &c small.
|
|
*/
|
|
while ((mlen -= 32) >= 0) {
|
|
sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
|
|
sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
|
|
sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
|
|
sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
|
|
w += 16;
|
|
}
|
|
mlen += 32;
|
|
while ((mlen -= 8) >= 0) {
|
|
sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
|
|
w += 4;
|
|
}
|
|
mlen += 8;
|
|
if (mlen == 0 && byte_swapped == 0)
|
|
continue;
|
|
REDUCE;
|
|
while ((mlen -= 2) >= 0) {
|
|
sum += *w++;
|
|
}
|
|
if (byte_swapped) {
|
|
REDUCE;
|
|
sum <<= 8;
|
|
byte_swapped = 0;
|
|
if (mlen == -1) {
|
|
s_util.c[1] = *(char *)w;
|
|
sum += s_util.s;
|
|
mlen = 0;
|
|
} else
|
|
mlen = -1;
|
|
} else if (mlen == -1)
|
|
s_util.c[0] = *(char *)w;
|
|
}
|
|
if (len)
|
|
printf("cksum: out of data\n");
|
|
if (mlen == -1) {
|
|
/* The last mbuf has odd # of bytes. Follow the
|
|
standard (the odd byte may be shifted left by 8 bits
|
|
or not as determined by endian-ness of the machine) */
|
|
s_util.c[1] = 0;
|
|
sum += s_util.s;
|
|
}
|
|
REDUCE;
|
|
return (~sum & 0xffff);
|
|
}
|