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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 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 xt_statistic_match[] = {
- {
- .name = "statistic",
- .family = AF_INET,
- .checkentry = checkentry,
- .match = match,
- .matchsize = sizeof(struct xt_statistic_info),
- .me = THIS_MODULE,
- },
- {
- .name = "statistic",
- .family = AF_INET6,
- .checkentry = checkentry,
- .match = match,
- .matchsize = sizeof(struct xt_statistic_info),
- .me = THIS_MODULE,
- },
- };
- static int __init xt_statistic_init(void)
- {
- return xt_register_matches(xt_statistic_match,
- ARRAY_SIZE(xt_statistic_match));
- }
- static void __exit xt_statistic_fini(void)
- {
- xt_unregister_matches(xt_statistic_match,
- ARRAY_SIZE(xt_statistic_match));
- }
- module_init(xt_statistic_init);
- module_exit(xt_statistic_fini);
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