2 * Copyright (c) 2006 Patrick McHardy <kaber@trash.net>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
8 * Based on ipt_random and ipt_nth by Fabrice MARIE <fabrice@netfilter.org>.
11 #include <linux/init.h>
12 #include <linux/spinlock.h>
13 #include <linux/skbuff.h>
14 #include <linux/net.h>
16 #include <linux/netfilter/xt_statistic.h>
17 #include <linux/netfilter/x_tables.h>
19 MODULE_LICENSE("GPL");
20 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
21 MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)");
22 MODULE_ALIAS("ipt_statistic");
23 MODULE_ALIAS("ip6t_statistic");
25 static DEFINE_SPINLOCK(nth_lock);
28 statistic_mt(const struct sk_buff *skb, const struct xt_match_param *par)
30 struct xt_statistic_info *info = (void *)par->matchinfo;
31 bool ret = info->flags & XT_STATISTIC_INVERT;
34 case XT_STATISTIC_MODE_RANDOM:
35 if ((net_random() & 0x7FFFFFFF) < info->u.random.probability)
38 case XT_STATISTIC_MODE_NTH:
40 spin_lock_bh(&nth_lock);
41 if (info->u.nth.count++ == info->u.nth.every) {
42 info->u.nth.count = 0;
45 spin_unlock_bh(&nth_lock);
53 statistic_mt_check(const char *tablename, const void *entry,
54 const struct xt_match *match, void *matchinfo,
55 unsigned int hook_mask)
57 struct xt_statistic_info *info = matchinfo;
59 if (info->mode > XT_STATISTIC_MODE_MAX ||
60 info->flags & ~XT_STATISTIC_MASK)
66 static struct xt_match xt_statistic_mt_reg __read_mostly = {
69 .family = NFPROTO_UNSPEC,
70 .match = statistic_mt,
71 .checkentry = statistic_mt_check,
72 .matchsize = sizeof(struct xt_statistic_info),
76 static int __init statistic_mt_init(void)
78 return xt_register_match(&xt_statistic_mt_reg);
81 static void __exit statistic_mt_exit(void)
83 xt_unregister_match(&xt_statistic_mt_reg);
86 module_init(statistic_mt_init);
87 module_exit(statistic_mt_exit);