mirror of
https://git.hardenedbsd.org/hardenedbsd/HardenedBSD.git
synced 2024-11-23 03:11:10 +01:00
85 lines
2.7 KiB
C
85 lines
2.7 KiB
C
|
/*-
|
||
|
|
* SPDX-License-Identifier: BSD-3-Clause
|
||
|
|
*
|
||
|
|
* Copyright (c) 1989, 1993
|
||
|
|
* The Regents of the University of California. All rights reserved.
|
||
|
|
*
|
||
|
|
* This code is derived from software contributed to Berkeley by
|
||
|
|
* Mike Muuss.
|
||
|
|
*
|
||
|
|
* 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. 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.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <string.h>
|
||
|
|
|
||
|
|
#include "utils.h"
|
||
|
|
|
||
|
|
/*
|
||
|
|
* in_cksum --
|
||
|
|
* Checksum routine for Internet Protocol family headers (C Version)
|
||
|
|
*/
|
||
|
|
u_short
|
||
|
|
in_cksum(u_char *addr, int len)
|
||
|
|
{
|
||
|
|
int nleft, sum;
|
||
|
|
u_char *w;
|
||
|
|
union {
|
||
|
|
u_short us;
|
||
|
|
u_char uc[2];
|
||
|
|
} last;
|
||
|
|
u_short answer;
|
||
|
|
|
||
|
|
nleft = len;
|
||
|
|
sum = 0;
|
||
|
|
w = addr;
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Our algorithm is simple, using a 32 bit accumulator (sum), we add
|
||
|
|
* sequential 16 bit words to it, and at the end, fold back all the
|
||
|
|
* carry bits from the top 16 bits into the lower 16 bits.
|
||
|
|
*/
|
||
|
|
while (nleft > 1) {
|
||
|
|
u_short data;
|
||
|
|
|
||
|
|
memcpy(&data, w, sizeof(data));
|
||
|
|
sum += data;
|
||
|
|
w += sizeof(data);
|
||
|
|
nleft -= sizeof(data);
|
||
|
|
}
|
||
|
|
|
||
|
|
/* mop up an odd byte, if necessary */
|
||
|
|
if (nleft == 1) {
|
||
|
|
last.uc[0] = *w;
|
||
|
|
last.uc[1] = 0;
|
||
|
|
sum += last.us;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* add back carry outs from top 16 bits to low 16 bits */
|
||
|
|
sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
|
||
|
|
sum += (sum >> 16); /* add carry */
|
||
|
|
answer = ~sum; /* truncate to 16 bits */
|
||
|
|
return(answer);
|
||
|
|
}
|