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/*
* Copyright (c) 2006 Patrick McHardy <kaber@trash.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Based on ipt_random and ipt_nth by Fabrice MARIE <fabrice@netfilter.org>.
*/
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/skbuff.h>
#include <linux/net.h>
#include <linux/netfilter/xt_statistic.h>
#include <linux/netfilter/x_tables.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_DESCRIPTION("xtables statistical match module");
MODULE_ALIAS("ipt_statistic");
MODULE_ALIAS("ip6t_statistic");
static DEFINE_SPINLOCK(nth_lock);
static int
match(const struct sk_buff *skb,
const struct net_device *in, const struct net_device *out,
const struct xt_match *match, const void *matchinfo,
int offset, unsigned int protoff, int *hotdrop)
{
struct xt_statistic_info *info = (struct xt_statistic_info *)matchinfo;
int ret = info->flags & XT_STATISTIC_INVERT ? 1 : 0;
switch (info->mode) {
case XT_STATISTIC_MODE_RANDOM:
if ((net_random() & 0x7FFFFFFF) < info->u.random.probability)
ret ^= 1;
break;
case XT_STATISTIC_MODE_NTH:
info = info->master;
spin_lock_bh(&nth_lock);
if (info->u.nth.count++ == info->u.nth.every) {
info->u.nth.count = 0;
ret ^= 1;
}
spin_unlock_bh(&nth_lock);
break;
}
return ret;
}
static int
checkentry(const char *tablename, const void *entry,
const struct xt_match *match, void *matchinfo,
unsigned int matchsize, unsigned int hook_mask)
{
struct xt_statistic_info *info = (struct xt_statistic_info *)matchinfo;
if (info->mode > XT_STATISTIC_MODE_MAX ||
info->flags & ~XT_STATISTIC_MASK)
return 0;
info->master = info;
return 1;
}
static struct xt_match statistic_match = {
.name = "statistic",
.match = match,
.matchsize = sizeof(struct xt_statistic_info),
.checkentry = checkentry,
.family = AF_INET,
.me = THIS_MODULE,
};
static struct xt_match statistic_match6 = {
.name = "statistic",
.match = match,
.matchsize = sizeof(struct xt_statistic_info),
.checkentry = checkentry,
.family = AF_INET6,
.me = THIS_MODULE,
};
static int __init xt_statistic_init(void)
{
int ret;
ret = xt_register_match(&statistic_match);
if (ret)
goto err1;
ret = xt_register_match(&statistic_match6);
if (ret)
goto err2;
return ret;
err2:
xt_unregister_match(&statistic_match);
err1:
return ret;
}
static void __exit xt_statistic_fini(void)
{
xt_unregister_match(&statistic_match6);
xt_unregister_match(&statistic_match);
}
module_init(xt_statistic_init);
module_exit(xt_statistic_fini);
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