/*

 * 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>

 *

 * Based on net/ipv4/xfrm4_tunnel.c

 *

 */

#include <linux/module.h>

#include <linux/xfrm.h>

#include <linux/list.h>

#include <net/ip.h>

#include <net/xfrm.h>

#include <net/ipv6.h>

#include <linux/ipv6.h>

#include <linux/icmpv6.h>

#include <linux/mutex.h>

/*

 * xfrm_tunnel_spi things are for allocating unique id ("spi")

 * per xfrm_address_t.

 */

struct xfrm6_tunnel_spi {

	struct hlist_node list_byaddr;

	struct hlist_node list_byspi;

	xfrm_address_t addr;

	u32 spi;

	atomic_t refcnt;

};

static DEFINE_RWLOCK(xfrm6_tunnel_spi_lock);

static u32 xfrm6_tunnel_spi;

#define XFRM6_TUNNEL_SPI_MIN	1

#define XFRM6_TUNNEL_SPI_MAX	0xffffffff

static struct kmem_cache *xfrm6_tunnel_spi_kmem __read_mostly;

#define XFRM6_TUNNEL_SPI_BYADDR_HSIZE 256

#define XFRM6_TUNNEL_SPI_BYSPI_HSIZE 256

static struct hlist_head xfrm6_tunnel_spi_byaddr[XFRM6_TUNNEL_SPI_BYADDR_HSIZE];

static struct hlist_head xfrm6_tunnel_spi_byspi[XFRM6_TUNNEL_SPI_BYSPI_HSIZE];

static inline unsigned xfrm6_tunnel_spi_hash_byaddr(xfrm_address_t *addr)

{

	unsigned h;

	h = (__force u32)(addr->a6[0] ^ addr->a6[1] ^ addr->a6[2] ^ addr->a6[3]);

	h ^= h >> 16;

	h ^= h >> 8;

	h &= XFRM6_TUNNEL_SPI_BYADDR_HSIZE - 1;

	return h;

}

static inline unsigned xfrm6_tunnel_spi_hash_byspi(u32 spi)

{

	return spi % XFRM6_TUNNEL_SPI_BYSPI_HSIZE;

}

static int xfrm6_tunnel_spi_init(void)

{

	int i;

	xfrm6_tunnel_spi = 0;

	xfrm6_tunnel_spi_kmem = kmem_cache_create("xfrm6_tunnel_spi",

						  sizeof(struct xfrm6_tunnel_spi),

						  0, SLAB_HWCACHE_ALIGN,

						  NULL);

	if (!xfrm6_tunnel_spi_kmem)

		return -ENOMEM;

	for (i = 0; i < XFRM6_TUNNEL_SPI_BYADDR_HSIZE; i++)

		INIT_HLIST_HEAD(&xfrm6_tunnel_spi_byaddr[i]);

	for (i = 0; i < XFRM6_TUNNEL_SPI_BYSPI_HSIZE; i++)

		INIT_HLIST_HEAD(&xfrm6_tunnel_spi_byspi[i]);

	return 0;

}

static void xfrm6_tunnel_spi_fini(void)

{

	int i;

	for (i = 0; i < XFRM6_TUNNEL_SPI_BYADDR_HSIZE; i++) {

		if (!hlist_empty(&xfrm6_tunnel_spi_byaddr[i]))

			return;

	}

	for (i = 0; i < XFRM6_TUNNEL_SPI_BYSPI_HSIZE; i++) {

		if (!hlist_empty(&xfrm6_tunnel_spi_byspi[i]))

			return;

	}

	kmem_cache_destroy(xfrm6_tunnel_spi_kmem);

	xfrm6_tunnel_spi_kmem = NULL;

}

static struct xfrm6_tunnel_spi *__xfrm6_tunnel_spi_lookup(xfrm_address_t *saddr)

{

	struct xfrm6_tunnel_spi *x6spi;

	struct hlist_node *pos;

	hlist_for_each_entry(x6spi, pos,

			     &xfrm6_tunnel_spi_byaddr[xfrm6_tunnel_spi_hash_byaddr(saddr)],

			     list_byaddr) {

		if (memcmp(&x6spi->addr, saddr, sizeof(x6spi->addr)) == 0)

			return x6spi;

	}

	return NULL;

}

__be32 xfrm6_tunnel_spi_lookup(xfrm_address_t *saddr)

{

	struct xfrm6_tunnel_spi *x6spi;

	u32 spi;

	read_lock_bh(&xfrm6_tunnel_spi_lock);

	x6spi = __xfrm6_tunnel_spi_lookup(saddr);

	spi = x6spi ? x6spi->spi : 0;

	read_unlock_bh(&xfrm6_tunnel_spi_lock);

	return htonl(spi);

}

EXPORT_SYMBOL(xfrm6_tunnel_spi_lookup);

static int __xfrm6_tunnel_spi_check(u32 spi)

{

	struct xfrm6_tunnel_spi *x6spi;

	int index = xfrm6_tunnel_spi_hash_byspi(spi);

	struct hlist_node *pos;

	hlist_for_each_entry(x6spi, pos,

			     &xfrm6_tunnel_spi_byspi[index],

			     list_byspi) {

		if (x6spi->spi == spi)

			return -1;

	}

	return index;

}

static u32 __xfrm6_tunnel_alloc_spi(xfrm_address_t *saddr)

{

	u32 spi;

	struct xfrm6_tunnel_spi *x6spi;

	int index;

	if (xfrm6_tunnel_spi < XFRM6_TUNNEL_SPI_MIN ||

	    xfrm6_tunnel_spi >= XFRM6_TUNNEL_SPI_MAX)

		xfrm6_tunnel_spi = XFRM6_TUNNEL_SPI_MIN;

	else

		xfrm6_tunnel_spi++;

	for (spi = xfrm6_tunnel_spi; spi <= XFRM6_TUNNEL_SPI_MAX; spi++) {

		index = __xfrm6_tunnel_spi_check(spi);

		if (index >= 0)

			goto alloc_spi;

	}

	for (spi = XFRM6_TUNNEL_SPI_MIN; spi < xfrm6_tunnel_spi; spi++) {

		index = __xfrm6_tunnel_spi_check(spi);

		if (index >= 0)

			goto alloc_spi;

	}

	spi = 0;

	goto out;

alloc_spi:

	xfrm6_tunnel_spi = spi;

	x6spi = kmem_cache_alloc(xfrm6_tunnel_spi_kmem, GFP_ATOMIC);

	if (!x6spi)

		goto out;

	memcpy(&x6spi->addr, saddr, sizeof(x6spi->addr));

	x6spi->spi = spi;

	atomic_set(&x6spi->refcnt, 1);

	hlist_add_head(&x6spi->list_byspi, &xfrm6_tunnel_spi_byspi[index]);

	index = xfrm6_tunnel_spi_hash_byaddr(saddr);

	hlist_add_head(&x6spi->list_byaddr, &xfrm6_tunnel_spi_byaddr[index]);

out:

	return spi;

}

__be32 xfrm6_tunnel_alloc_spi(xfrm_address_t *saddr)

{

	struct xfrm6_tunnel_spi *x6spi;

	u32 spi;

	write_lock_bh(&xfrm6_tunnel_spi_lock);

	x6spi = __xfrm6_tunnel_spi_lookup(saddr);

	if (x6spi) {

		atomic_inc(&x6spi->refcnt);

		spi = x6spi->spi;

	} else

		spi = __xfrm6_tunnel_alloc_spi(saddr);

	write_unlock_bh(&xfrm6_tunnel_spi_lock);

	return htonl(spi);

}

EXPORT_SYMBOL(xfrm6_tunnel_alloc_spi);

void xfrm6_tunnel_free_spi(xfrm_address_t *saddr)

{

	struct xfrm6_tunnel_spi *x6spi;

	struct hlist_node *pos, *n;

	write_lock_bh(&xfrm6_tunnel_spi_lock);

	hlist_for_each_entry_safe(x6spi, pos, n,

				  &xfrm6_tunnel_spi_byaddr[xfrm6_tunnel_spi_hash_byaddr(saddr)],

				  list_byaddr)

	{

		if (memcmp(&x6spi->addr, saddr, sizeof(x6spi->addr)) == 0) {

			if (atomic_dec_and_test(&x6spi->refcnt)) {

				hlist_del(&x6spi->list_byaddr);

				hlist_del(&x6spi->list_byspi);

				kmem_cache_free(xfrm6_tunnel_spi_kmem, x6spi);

				break;

			}

		}

	}

	write_unlock_bh(&xfrm6_tunnel_spi_lock);

}

EXPORT_SYMBOL(xfrm6_tunnel_free_spi);

static int xfrm6_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)

{

	skb_push(skb, -skb_network_offset(skb));

	return 0;

}

static int xfrm6_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)

{

	return skb_network_header(skb)[IP6CB(skb)->nhoff];

}

static int xfrm6_tunnel_rcv(struct sk_buff *skb)

{

	struct ipv6hdr *iph = ipv6_hdr(skb);

	__be32 spi;

	spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&iph->saddr);

	return xfrm6_rcv_spi(skb, IPPROTO_IPV6, spi) > 0 ? : 0;

}

static int xfrm6_tunnel_err(struct sk_buff *skb, struct inet6_skb_parm *opt,

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

{

	/* xfrm6_tunnel native err handling */

	switch (type) {

	case ICMPV6_DEST_UNREACH:

		switch (code) {

		case ICMPV6_NOROUTE:

		case ICMPV6_ADM_PROHIBITED:

		case ICMPV6_NOT_NEIGHBOUR:

		case ICMPV6_ADDR_UNREACH:

		case ICMPV6_PORT_UNREACH:

		default:

			break;

		}

		break;

	case ICMPV6_PKT_TOOBIG:

		break;

	case ICMPV6_TIME_EXCEED:

		switch (code) {

		case ICMPV6_EXC_HOPLIMIT:

			break;

		case ICMPV6_EXC_FRAGTIME:

		default:

			break;

		}

		break;

	case ICMPV6_PARAMPROB:

		switch (code) {

		case ICMPV6_HDR_FIELD: break;

		case ICMPV6_UNK_NEXTHDR: break;

		case ICMPV6_UNK_OPTION: break;

		}

		break;

	default:

		break;

	}

	return 0;

}

static int xfrm6_tunnel_init_state(struct xfrm_state *x)

{

	if (x->props.mode != XFRM_MODE_TUNNEL)

		return -EINVAL;

	if (x->encap)

		return -EINVAL;

	x->props.header_len = sizeof(struct ipv6hdr);

	return 0;

}

static void xfrm6_tunnel_destroy(struct xfrm_state *x)

{

	xfrm6_tunnel_free_spi((xfrm_address_t *)&x->props.saddr);

}

static const struct xfrm_type xfrm6_tunnel_type = {

	.description	= "IP6IP6",

	.owner          = THIS_MODULE,

	.proto		= IPPROTO_IPV6,

	.init_state	= xfrm6_tunnel_init_state,

	.destructor	= xfrm6_tunnel_destroy,

	.input		= xfrm6_tunnel_input,

	.output		= xfrm6_tunnel_output,

};

static struct xfrm6_tunnel xfrm6_tunnel_handler = {

	.handler	= xfrm6_tunnel_rcv,

	.err_handler	= xfrm6_tunnel_err,

	.priority	= 2,

};

static struct xfrm6_tunnel xfrm46_tunnel_handler = {

	.handler	= xfrm6_tunnel_rcv,

	.err_handler	= xfrm6_tunnel_err,

	.priority	= 2,

};

static int __init xfrm6_tunnel_init(void)

{

	if (xfrm_register_type(&xfrm6_tunnel_type, AF_INET6) < 0)

}

static void __exit xfrm6_tunnel_fini(void)

{

	xfrm6_tunnel_spi_fini();

	xfrm6_tunnel_deregister(&xfrm46_tunnel_handler, AF_INET);

	xfrm6_tunnel_deregister(&xfrm6_tunnel_handler, AF_INET6);

	xfrm_unregister_type(&xfrm6_tunnel_type, AF_INET6);

}

module_init(xfrm6_tunnel_init);

module_exit(xfrm6_tunnel_fini);

MODULE_LICENSE("GPL");

MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_IPV6);