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/* $OpenBSD: in_cksum.c,v 1.2 2005/05/05 14:28:34 miod Exp $ */
/*
* Copyright (C) 1995, 1996 Wolfgang Solfrank.
* Copyright (C) 1995, 1996 TooLs GmbH.
* 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 TooLs GmbH.
* 4. The name of TooLs GmbH may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``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 TOOLS GMBH 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.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/socketvar.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#define REDUCE (sum = (sum & 0xffff) + (sum >> 16))
#define ROL (sum <<= 8)
#define ADDB (ROL, sum += *w, byte_swapped ^= 1)
#define ADDS (sum += *(u_short *)w)
#define SHIFT(n) (w += (n), mlen -= (n))
#define ADDCARRY do { while (sum > 0xffff) REDUCE; } while (0)
static __inline__ int
in_cksum_internal(struct mbuf *m, int off, int len, u_int sum)
{
u_char *w;
int mlen;
int byte_swapped = 0;
for (; m && len; m = m->m_next) {
if (m->m_len == 0)
continue;
w = mtod(m, u_char *) + off;
mlen = m->m_len - off;
off = 0;
if (len < mlen)
mlen = len;
len -= mlen;
if ((long)w & 1) {
REDUCE;
ADDB;
SHIFT(1);
}
while (mlen >= 2) {
ADDS;
SHIFT(2);
}
REDUCE;
if (mlen == 1)
ADDB;
}
if (byte_swapped) {
REDUCE;
ROL;
}
ADDCARRY;
return (0xffff ^ sum);
}
int
in_cksum(struct mbuf *m, int len)
{
return (in_cksum_internal(m, 0, len, 0));
}
int
in4_cksum(struct mbuf *m, uint8_t nxt, int off, int len)
{
u_int16_t *w;
u_int sum = 0;
struct ipovly ipov;
if (nxt != 0) {
/* pseudo header */
bzero(&ipov, sizeof(ipov));
ipov.ih_len = htons(len);
ipov.ih_pr = nxt;
ipov.ih_src = mtod(m, struct ip *)->ip_src;
ipov.ih_dst = mtod(m, struct ip *)->ip_dst;
w = (u_int16_t *)&ipov;
/* assumes sizeof(ipov) == 20 */
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];
}
/* skip unnecessary part */
while (m && off > 0) {
if (m->m_len > off)
break;
off -= m->m_len;
m = m->m_next;
}
return (in_cksum_internal(m, off, len, sum));
}
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