/*
   * Copyright (C)2003,2004 USAGI/WIDE Project
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   *
   * Authors	Mitsuru KANDA  <mk@linux-ipv6.org>
   * 		YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
   */

  #include <linux/icmpv6.h>

  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/mutex.h>
  #include <linux/netdevice.h>
  #include <linux/skbuff.h>

  #include <linux/slab.h>

  #include <net/ipv6.h>

  #include <net/protocol.h>
  #include <net/xfrm.h>

  static struct xfrm6_tunnel __rcu *tunnel6_handlers __read_mostly;
  static struct xfrm6_tunnel __rcu *tunnel46_handlers __read_mostly;

  static DEFINE_MUTEX(tunnel6_mutex);

  int xfrm6_tunnel_register(struct xfrm6_tunnel *handler, unsigned short family)

  {

  	struct xfrm6_tunnel __rcu **pprev;
  	struct xfrm6_tunnel *t;

  	int ret = -EEXIST;
  	int priority = handler->priority;
  
  	mutex_lock(&tunnel6_mutex);

  	for (pprev = (family == AF_INET6) ? &tunnel6_handlers : &tunnel46_handlers;

  	     (t = rcu_dereference_protected(*pprev,
  			lockdep_is_held(&tunnel6_mutex))) != NULL;
  	     pprev = &t->next) {
  		if (t->priority > priority)

  			break;

  		if (t->priority == priority)

  			goto err;
  	}
  
  	handler->next = *pprev;

  	rcu_assign_pointer(*pprev, handler);

  
  	ret = 0;
  
  err:
  	mutex_unlock(&tunnel6_mutex);
  
  	return ret;
  }
  
  EXPORT_SYMBOL(xfrm6_tunnel_register);

  int xfrm6_tunnel_deregister(struct xfrm6_tunnel *handler, unsigned short family)

  {

  	struct xfrm6_tunnel __rcu **pprev;
  	struct xfrm6_tunnel *t;

  	int ret = -ENOENT;
  
  	mutex_lock(&tunnel6_mutex);

  	for (pprev = (family == AF_INET6) ? &tunnel6_handlers : &tunnel46_handlers;

  	     (t = rcu_dereference_protected(*pprev,
  			lockdep_is_held(&tunnel6_mutex))) != NULL;
  	     pprev = &t->next) {
  		if (t == handler) {

  			*pprev = handler->next;
  			ret = 0;
  			break;
  		}
  	}
  
  	mutex_unlock(&tunnel6_mutex);
  
  	synchronize_net();
  
  	return ret;
  }
  
  EXPORT_SYMBOL(xfrm6_tunnel_deregister);

  #define for_each_tunnel_rcu(head, handler)		\
  	for (handler = rcu_dereference(head);		\
  	     handler != NULL;				\
  	     handler = rcu_dereference(handler->next))	\

  static int tunnel6_rcv(struct sk_buff *skb)

  {

  	struct xfrm6_tunnel *handler;

  	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
  		goto drop;

  	for_each_tunnel_rcu(tunnel6_handlers, handler)

  		if (!handler->handler(skb))
  			return 0;

  	icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);

  
  drop:

  	kfree_skb(skb);
  	return 0;
  }

  static int tunnel46_rcv(struct sk_buff *skb)

  {

  	struct xfrm6_tunnel *handler;

  	if (!pskb_may_pull(skb, sizeof(struct iphdr)))

  		goto drop;

  	for_each_tunnel_rcu(tunnel46_handlers, handler)

  		if (!handler->handler(skb))
  			return 0;

  	icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);

  
  drop:
  	kfree_skb(skb);
  	return 0;
  }

  static void tunnel6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,

  			u8 type, u8 code, int offset, __be32 info)

  {
  	struct xfrm6_tunnel *handler;

  	for_each_tunnel_rcu(tunnel6_handlers, handler)

  		if (!handler->err_handler(skb, opt, type, code, offset, info))
  			break;
  }

  static const struct inet6_protocol tunnel6_protocol = {

  	.handler	= tunnel6_rcv,
  	.err_handler	= tunnel6_err,
  	.flags          = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
  };

  static const struct inet6_protocol tunnel46_protocol = {

  	.handler	= tunnel46_rcv,
  	.err_handler	= tunnel6_err,
  	.flags          = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
  };

  static int __init tunnel6_init(void)
  {
  	if (inet6_add_protocol(&tunnel6_protocol, IPPROTO_IPV6)) {
  		printk(KERN_ERR "tunnel6 init(): can't add protocol
  ");
  		return -EAGAIN;
  	}

  	if (inet6_add_protocol(&tunnel46_protocol, IPPROTO_IPIP)) {
  		printk(KERN_ERR "tunnel6 init(): can't add protocol
  ");
  		inet6_del_protocol(&tunnel6_protocol, IPPROTO_IPV6);
  		return -EAGAIN;
  	}

  	return 0;
  }
  
  static void __exit tunnel6_fini(void)
  {

  	if (inet6_del_protocol(&tunnel46_protocol, IPPROTO_IPIP))
  		printk(KERN_ERR "tunnel6 close: can't remove protocol
  ");

  	if (inet6_del_protocol(&tunnel6_protocol, IPPROTO_IPV6))
  		printk(KERN_ERR "tunnel6 close: can't remove protocol
  ");
  }
  
  module_init(tunnel6_init);
  module_exit(tunnel6_fini);
  MODULE_LICENSE("GPL");