diff options
Diffstat (limited to 'net/netfilter/xt_statistic.c')
-rw-r--r-- | net/netfilter/xt_statistic.c | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/net/netfilter/xt_statistic.c b/net/netfilter/xt_statistic.c new file mode 100644 index 0000000..0d75141 --- /dev/null +++ b/net/netfilter/xt_statistic.c @@ -0,0 +1,84 @@ +/* + * 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: statistics-based matching (\"Nth\", random)"); +MODULE_ALIAS("ipt_statistic"); +MODULE_ALIAS("ip6t_statistic"); + +static DEFINE_SPINLOCK(nth_lock); + +static bool +statistic_mt(const struct sk_buff *skb, const struct xt_match_param *par) +{ + struct xt_statistic_info *info = (void *)par->matchinfo; + bool ret = info->flags & XT_STATISTIC_INVERT; + + switch (info->mode) { + case XT_STATISTIC_MODE_RANDOM: + if ((net_random() & 0x7FFFFFFF) < info->u.random.probability) + ret = !ret; + 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 = !ret; + } + spin_unlock_bh(&nth_lock); + break; + } + + return ret; +} + +static bool statistic_mt_check(const struct xt_mtchk_param *par) +{ + struct xt_statistic_info *info = par->matchinfo; + + if (info->mode > XT_STATISTIC_MODE_MAX || + info->flags & ~XT_STATISTIC_MASK) + return false; + info->master = info; + return true; +} + +static struct xt_match xt_statistic_mt_reg __read_mostly = { + .name = "statistic", + .revision = 0, + .family = NFPROTO_UNSPEC, + .match = statistic_mt, + .checkentry = statistic_mt_check, + .matchsize = sizeof(struct xt_statistic_info), + .me = THIS_MODULE, +}; + +static int __init statistic_mt_init(void) +{ + return xt_register_match(&xt_statistic_mt_reg); +} + +static void __exit statistic_mt_exit(void) +{ + xt_unregister_match(&xt_statistic_mt_reg); +} + +module_init(statistic_mt_init); +module_exit(statistic_mt_exit); |