[NETFILTER]: x_tables: add statistic match
Add statistic match which is a combination of the nth and random matches.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netfilter/xt_statistic.c b/net/netfilter/xt_statistic.c
new file mode 100644
index 0000000..de1037f
--- /dev/null
+++ b/net/netfilter/xt_statistic.c
@@ -0,0 +1,112 @@
+/*
+ * 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);