mod_drop.c

/*
 * mod_drop.c
 *
 * Copyright (c) 2001 Dug Song <dugsong@monkey.org>
 *
 * $Id: mod_drop.c,v 1.3 2002/04/07 22:55:20 dugsong Exp $
 */

#include "config.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "pkt.h"
#include "mod.h"

#define DROP_FIRST	1
#define DROP_LAST	2
#define DROP_RANDOM	3

struct drop_data {
	rand_t	*rnd;
	int	 which;
	int	 percent;
};

void *
drop_close(void *d)
{
	struct drop_data *data = (struct drop_data *)d;
	
	if (data != NULL) {
		rand_close(data->rnd);
		free(data);
	}
	return (NULL);
}

void *
drop_open(int argc, char *argv[])
{
	struct drop_data *data;
	
	if (argc != 3)
		return (NULL);
	
	if ((data = calloc(1, sizeof(*data))) == NULL)
		return (NULL);

	data->rnd = rand_open();
	
	if (strcasecmp(argv[1], "first") == 0)
		data->which = DROP_FIRST;
	else if (strcasecmp(argv[1], "last") == 0)
		data->which = DROP_LAST;
	else if (strcasecmp(argv[1], "random") == 0)
		data->which = DROP_RANDOM;
	else
		return (drop_close(data));
	
	if ((data->percent = atoi(argv[2])) <= 0 || data->percent > 100)
		return (drop_close(data));

	return (data);
}

int
drop_apply(void *d, struct pktq *pktq)
{
	struct drop_data *data = (struct drop_data *)d;
	struct pkt *pkt;

	if (data->percent < 100 &&
	    (rand_uint16(data->rnd) % 100) > data->percent)
		return (0);
	
	if (data->which == DROP_FIRST)
		pkt = TAILQ_FIRST(pktq);
	else if (data->which == DROP_LAST)
		pkt = TAILQ_LAST(pktq, pktq);
	else
		pkt = pktq_random(data->rnd, pktq);

	TAILQ_REMOVE(pktq, pkt, pkt_next);
	pkt_free(pkt);
	
	return (0);
}

struct mod mod_drop = {
	"drop",					/* name */
	"drop first|last|random <prob-%>",	/* usage */
	drop_open,				/* open */
	drop_apply,				/* apply */
	drop_close				/* close */
};