/* Kernel module to match connection tracking information. */
  
  /* (C) 1999-2001 Paul `Rusty' Russell

   * (C) 2002-2005 Netfilter Core Team <coreteam@netfilter.org>

   *
   * 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.
   */
  
  #include <linux/module.h>
  #include <linux/skbuff.h>

  #include <net/netfilter/nf_conntrack.h>

  #include <linux/netfilter/x_tables.h>
  #include <linux/netfilter/xt_state.h>

  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");

  MODULE_DESCRIPTION("ip[6]_tables connection tracking state match module");
  MODULE_ALIAS("ipt_state");
  MODULE_ALIAS("ip6t_state");

  static bool

  state_mt(const struct sk_buff *skb, const struct xt_match_param *par)

  {

  	const struct xt_state_info *sinfo = par->matchinfo;

  	enum ip_conntrack_info ctinfo;
  	unsigned int statebit;

  	if (nf_ct_is_untracked(skb))

  		statebit = XT_STATE_UNTRACKED;

  	else if (!nf_ct_get(skb, &ctinfo))

  		statebit = XT_STATE_INVALID;

  	else

  		statebit = XT_STATE_BIT(ctinfo);

  
  	return (sinfo->statemask & statebit);
  }

  static bool state_mt_check(const struct xt_mtchk_param *par)

  {

  	if (nf_ct_l3proto_try_module_get(par->match->family) < 0) {

  		printk(KERN_WARNING "can't load conntrack support for "

  				    "proto=%u
  ", par->match->family);

  		return false;

  	}

  	return true;

  }

  static void state_mt_destroy(const struct xt_mtdtor_param *par)

  {

  	nf_ct_l3proto_module_put(par->match->family);

  }

  static struct xt_match state_mt_reg[] __read_mostly = {

  	{
  		.name		= "state",

  		.family		= NFPROTO_IPV4,

  		.checkentry	= state_mt_check,
  		.match		= state_mt,
  		.destroy	= state_mt_destroy,

  		.matchsize	= sizeof(struct xt_state_info),
  		.me		= THIS_MODULE,
  	},
  	{
  		.name		= "state",

  		.family		= NFPROTO_IPV6,

  		.checkentry	= state_mt_check,
  		.match		= state_mt,
  		.destroy	= state_mt_destroy,

  		.matchsize	= sizeof(struct xt_state_info),
  		.me		= THIS_MODULE,
  	},

  };

  static int __init state_mt_init(void)

  {

  	return xt_register_matches(state_mt_reg, ARRAY_SIZE(state_mt_reg));

  }

  static void __exit state_mt_exit(void)

  {

  	xt_unregister_matches(state_mt_reg, ARRAY_SIZE(state_mt_reg));

  }

  module_init(state_mt_init);
  module_exit(state_mt_exit);