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/* tunnel4.c: Generic IP tunnel transformer.
 *
 * Copyright (C) 2003 David S. Miller (davem@redhat.com)
 */
 
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/icmp.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/xfrm.h>
 
static struct xfrm_tunnel *tunnel4_handlers;
static struct xfrm_tunnel *tunnel64_handlers;
static DEFINE_MUTEX(tunnel4_mutex);
 
static inline struct xfrm_tunnel **fam_handlers(unsigned short family)
{
	return (family == AF_INET) ? &tunnel4_handlers : &tunnel64_handlers;
}
 
int xfrm4_tunnel_register(struct xfrm_tunnel *handler, unsigned short family)
{
	struct xfrm_tunnel **pprev;
	int ret = -EEXIST;
	int priority = handler->priority;
 
	mutex_lock(&tunnel4_mutex);
 
	for (pprev = fam_handlers(family); *pprev; pprev = &(*pprev)->next) {
		if ((*pprev)->priority > priority)
			break;
		if ((*pprev)->priority == priority)
			goto err;
	}
 
	handler->next = *pprev;
	*pprev = handler;
 
	ret = 0;
 
err:
	mutex_unlock(&tunnel4_mutex);
 
	return ret;
}
 
EXPORT_SYMBOL(xfrm4_tunnel_register);
 
int xfrm4_tunnel_deregister(struct xfrm_tunnel *handler, unsigned short family)
{
	struct xfrm_tunnel **pprev;
	int ret = -ENOENT;
 
	mutex_lock(&tunnel4_mutex);
 
	for (pprev = fam_handlers(family); *pprev; pprev = &(*pprev)->next) {
		if (*pprev == handler) {
			*pprev = handler->next;
			ret = 0;
			break;
		}
	}
 
	mutex_unlock(&tunnel4_mutex);
 
	synchronize_net();
 
	return ret;
}
 
EXPORT_SYMBOL(xfrm4_tunnel_deregister);
 
static int tunnel4_rcv(struct sk_buff *skb)
{
	struct xfrm_tunnel *handler;
 
	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
		goto drop;
 
	for (handler = tunnel4_handlers; handler; handler = handler->next)
		if (!handler->handler(skb))
			return 0;
 
	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 
drop:
	kfree_skb(skb);
	return 0;
}
 
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
static int tunnel64_rcv(struct sk_buff *skb)
{
	struct xfrm_tunnel *handler;
 
	if (!pskb_may_pull(skb, sizeof(struct iphdr)))
		goto drop;
 
	for (handler = tunnel64_handlers; handler; handler = handler->next)
		if (!handler->handler(skb))
			return 0;
 
	icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
 
drop:
	kfree_skb(skb);
	return 0;
}
#endif
 
static void tunnel4_err(struct sk_buff *skb, u32 info)
{
	struct xfrm_tunnel *handler;
 
	for (handler = tunnel4_handlers; handler; handler = handler->next)
		if (!handler->err_handler(skb, info))
			break;
}
 
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
static void tunnel64_err(struct sk_buff *skb, u32 info)
{
	struct xfrm_tunnel *handler;
 
	for (handler = tunnel64_handlers; handler; handler = handler->next)
		if (!handler->err_handler(skb, info))
			break;
}
#endif
 
static struct net_protocol tunnel4_protocol = {
	.handler	=	tunnel4_rcv,
	.err_handler	=	tunnel4_err,
	.no_policy	=	1,
};
 
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
static struct net_protocol tunnel64_protocol = {
	.handler	=	tunnel64_rcv,
	.err_handler	=	tunnel64_err,
	.no_policy	=	1,
};
#endif
 
static int __init tunnel4_init(void)
{
	if (inet_add_protocol(&tunnel4_protocol, IPPROTO_IPIP)) {
		printk(KERN_ERR "tunnel4 init: can't add protocol\n");
		return -EAGAIN;
	}
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
	if (inet_add_protocol(&tunnel64_protocol, IPPROTO_IPV6)) {
		printk(KERN_ERR "tunnel64 init: can't add protocol\n");
		inet_del_protocol(&tunnel4_protocol, IPPROTO_IPIP);
		return -EAGAIN;
	}
#endif
	return 0;
}
 
static void __exit tunnel4_fini(void)
{
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
	if (inet_del_protocol(&tunnel64_protocol, IPPROTO_IPV6))
		printk(KERN_ERR "tunnel64 close: can't remove protocol\n");
#endif
	if (inet_del_protocol(&tunnel4_protocol, IPPROTO_IPIP))
		printk(KERN_ERR "tunnel4 close: can't remove protocol\n");
}
 
module_init(tunnel4_init);
module_exit(tunnel4_fini);
MODULE_LICENSE("GPL");