sendto_dbg.c

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <stdio.h>
#include <stdlib.h>
#include <netinet/in.h>

void *memcpy(void *dest, const void *src, size_t n);
static int first_time = 1;
static int cutoff = 25; /* default is 25% loss */

void sendto_dbg_init(int percent)
{
	/* percent is in integer form (i.e. 1 = 1%, 5 = 5%) */
	cutoff = percent;
	if( cutoff < 0 ) cutoff = 0;
	else if( cutoff > 100 ) cutoff = 100;

	printf("\n++++++++++ cutoff value is %d +++++++++\n", cutoff);
}

int sendto_dbg(int s, const char *buf, int len, int flags,
	       const struct sockaddr *to, int tolen )
{
	int 	ret;
	int	decision;
	struct sockaddr_in drop_addr;

	if( first_time )
	{
		struct timeval t;
		gettimeofday( &t, NULL );
		srand( t.tv_sec );
		printf("\n+++++++++\n seed is %d\n++++++++\n", (int)t.tv_sec);
		first_time = 0;
	}
        decision = rand() % 100 + 1;
	if( (cutoff > 0) && (decision <= cutoff ) ) {
		/*printf("dropping pkt\n");*/
		memcpy(&drop_addr, to, tolen);
		drop_addr.sin_port = htons(ntohs(drop_addr.sin_port) + 1);
		ret = sendto( s, buf, len, flags, (struct sockaddr *) &drop_addr, tolen );
		return(ret);
	}
	ret = sendto( s, buf, len, flags, to, tolen );
	return( ret );
}