/* 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, struct xt_action_param *par)

  {

  	const struct xt_state_info *sinfo = par->matchinfo;

  	enum ip_conntrack_info ctinfo;
  	unsigned int statebit;

  	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);

  	if (!ct)

  		statebit = XT_STATE_INVALID;

  	else {
  		if (nf_ct_is_untracked(ct))
  			statebit = XT_STATE_UNTRACKED;
  		else
  			statebit = XT_STATE_BIT(ctinfo);
  	}

  	return (sinfo->statemask & statebit);
  }

  static int state_mt_check(const struct xt_mtchk_param *par)

  {

  	int ret;
  
  	ret = nf_ct_l3proto_try_module_get(par->family);

  	if (ret < 0)

  		pr_info("cannot load conntrack support for proto=%u
  ",
  			par->family);

  	return ret;

  }

  static void state_mt_destroy(const struct xt_mtdtor_param *par)

  {

  	nf_ct_l3proto_module_put(par->family);

  }

  static struct xt_match state_mt_reg __read_mostly = {
  	.name       = "state",
  	.family     = NFPROTO_UNSPEC,
  	.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_match(&state_mt_reg);

  }

  static void __exit state_mt_exit(void)

  {

  	xt_unregister_match(&state_mt_reg);

  }

  module_init(state_mt_init);
  module_exit(state_mt_exit);