/*
   * Filtering ARP tables module.
   *
   * Copyright (C) 2002 David S. Miller (davem@redhat.com)
   *
   */
  
  #include <linux/module.h>

  #include <linux/netfilter/x_tables.h>

  #include <linux/netfilter_arp/arp_tables.h>

  #include <linux/slab.h>

  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
  MODULE_DESCRIPTION("arptables filter table");
  
  #define FILTER_VALID_HOOKS ((1 << NF_ARP_IN) | (1 << NF_ARP_OUT) | \
  			   (1 << NF_ARP_FORWARD))

  static int __net_init arptable_filter_table_init(struct net *net);

  static const struct xt_table packet_filter = {

  	.name		= "filter",
  	.valid_hooks	= FILTER_VALID_HOOKS,

  	.me		= THIS_MODULE,

  	.af		= NFPROTO_ARP,

  	.priority	= NF_IP_PRI_FILTER,

  	.table_init	= arptable_filter_table_init,

  };
  
  /* The work comes in here from netfilter.c */

  static unsigned int

  arptable_filter_hook(void *priv, struct sk_buff *skb,

  		     const struct nf_hook_state *state)

  {

  	return arpt_do_table(skb, state, state->net->ipv4.arptable_filter);

  }

  static struct nf_hook_ops *arpfilter_ops __read_mostly;

  static int __net_init arptable_filter_table_init(struct net *net)

  {

  	struct arpt_replace *repl;

  	int err;

  	if (net->ipv4.arptable_filter)
  		return 0;

  	repl = arpt_alloc_initial_table(&packet_filter);
  	if (repl == NULL)
  		return -ENOMEM;

  	err = arpt_register_table(net, &packet_filter, repl, arpfilter_ops,
  				  &net->ipv4.arptable_filter);

  	kfree(repl);

  	return err;

  }
  
  static void __net_exit arptable_filter_net_exit(struct net *net)
  {

  	if (!net->ipv4.arptable_filter)
  		return;

  	arpt_unregister_table(net, net->ipv4.arptable_filter, arpfilter_ops);

  	net->ipv4.arptable_filter = NULL;

  }
  
  static struct pernet_operations arptable_filter_net_ops = {

  	.exit = arptable_filter_net_exit,
  };

  static int __init arptable_filter_init(void)

  {

  	int ret;

  	arpfilter_ops = xt_hook_ops_alloc(&packet_filter, arptable_filter_hook);
  	if (IS_ERR(arpfilter_ops))
  		return PTR_ERR(arpfilter_ops);

  	ret = register_pernet_subsys(&arptable_filter_net_ops);

  	if (ret < 0) {
  		kfree(arpfilter_ops);

  		return ret;

  	}

  	ret = arptable_filter_table_init(&init_net);
  	if (ret) {
  		unregister_pernet_subsys(&arptable_filter_net_ops);
  		kfree(arpfilter_ops);
  	}

  	return ret;
  }

  static void __exit arptable_filter_fini(void)

  {

  	unregister_pernet_subsys(&arptable_filter_net_ops);

  	kfree(arpfilter_ops);

  }

  module_init(arptable_filter_init);
  module_exit(arptable_filter_fini);