60 lines
943 B
C
60 lines
943 B
C
|
/*
|
||
|
|
* BIRD Library -- IP One-Complement Checksum
|
||
|
|
*
|
||
|
|
* (c) 1999 Martin Mares <mj@ucw.cz>
|
||
|
|
*
|
||
|
|
* Can be freely distributed and used under the terms of the GNU GPL.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <stdarg.h>
|
||
|
|
|
||
|
|
#include "nest/bird.h"
|
||
|
|
#include "checksum.h"
|
||
|
|
|
||
|
|
static u16
|
||
|
|
ipsum_calc(void *frag, unsigned len, va_list args)
|
||
|
|
{
|
||
|
|
u16 sum = 0;
|
||
|
|
|
||
|
|
for(;;)
|
||
|
|
{
|
||
|
|
u16 *x = frag;
|
||
|
|
ASSERT(!(len % 2));
|
||
|
|
while (len)
|
||
|
|
{
|
||
|
|
u16 z = sum + *x++;
|
||
|
|
sum = z + (z < sum);
|
||
|
|
len -= 2;
|
||
|
|
}
|
||
|
|
frag = va_arg(args, void *);
|
||
|
|
if (!frag)
|
||
|
|
break;
|
||
|
|
len = va_arg(args, unsigned);
|
||
|
|
}
|
||
|
|
return sum;
|
||
|
|
}
|
||
|
|
|
||
|
|
int
|
||
|
|
ipsum_verify(void *frag, unsigned len, ...)
|
||
|
|
{
|
||
|
|
va_list args;
|
||
|
|
u16 sum;
|
||
|
|
|
||
|
|
va_start(args, len);
|
||
|
|
sum = ipsum_calc(frag, len, args);
|
||
|
|
va_end(args);
|
||
|
|
return sum == 0xffff;
|
||
|
|
}
|
||
|
|
|
||
|
|
u16
|
||
|
|
ipsum_calculate(void *frag, unsigned len, ...)
|
||
|
|
{
|
||
|
|
va_list args;
|
||
|
|
u16 sum;
|
||
|
|
|
||
|
|
va_start(args, len);
|
||
|
|
sum = ipsum_calc(frag, len, args);
|
||
|
|
va_end(args);
|
||
|
|
return 0xffff - sum;
|
||
|
|
}
|