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 struct xt_statistic_priv {
23 MODULE_LICENSE("GPL");
24 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
25 MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)");
26 MODULE_ALIAS("ipt_statistic");
27 MODULE_ALIAS("ip6t_statistic");
29 static DEFINE_SPINLOCK(nth_lock);
32 statistic_mt(const struct sk_buff *skb, const struct xt_match_param *par)
34 const struct xt_statistic_info *info = par->matchinfo;
35 bool ret = info->flags & XT_STATISTIC_INVERT;
38 case XT_STATISTIC_MODE_RANDOM:
39 if ((net_random() & 0x7FFFFFFF) < info->u.random.probability)
42 case XT_STATISTIC_MODE_NTH:
43 spin_lock_bh(&nth_lock);
44 if (info->master->count++ == info->u.nth.every) {
45 info->master->count = 0;
48 spin_unlock_bh(&nth_lock);
55 static bool statistic_mt_check(const struct xt_mtchk_param *par)
57 struct xt_statistic_info *info = par->matchinfo;
59 if (info->mode > XT_STATISTIC_MODE_MAX ||
60 info->flags & ~XT_STATISTIC_MASK)
63 info->master = kzalloc(sizeof(*info->master), GFP_KERNEL);
64 if (info->master == NULL) {
65 printk(KERN_ERR KBUILD_MODNAME ": Out of memory\n");
68 info->master->count = info->u.nth.count;
73 static void statistic_mt_destroy(const struct xt_mtdtor_param *par)
75 const struct xt_statistic_info *info = par->matchinfo;
80 static struct xt_match xt_statistic_mt_reg __read_mostly = {
83 .family = NFPROTO_UNSPEC,
84 .match = statistic_mt,
85 .checkentry = statistic_mt_check,
86 .destroy = statistic_mt_destroy,
87 .matchsize = sizeof(struct xt_statistic_info),
91 static int __init statistic_mt_init(void)
93 return xt_register_match(&xt_statistic_mt_reg);
96 static void __exit statistic_mt_exit(void)
98 xt_unregister_match(&xt_statistic_mt_reg);
101 module_init(statistic_mt_init);
102 module_exit(statistic_mt_exit);