/*

 * IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173

 *

 * Copyright (C)2003 USAGI/WIDE Project

 *

 * Author	Mitsuru KANDA  <mk@linux-ipv6.org>

 *

 * 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

 */

/*

 * [Memo]

 *

 * Outbound:

 *  The compression of IP datagram MUST be done before AH/ESP processing,

 *  fragmentation, and the addition of Hop-by-Hop/Routing header.

 *

 * Inbound:

 *  The decompression of IP datagram MUST be done after the reassembly,

 *  AH/ESP processing.

 */

#include <linux/module.h>

#include <net/ip.h>

#include <net/xfrm.h>

#include <net/ipcomp.h>

#include <linux/crypto.h>

#include <linux/err.h>

#include <linux/pfkeyv2.h>

#include <linux/random.h>

#include <linux/percpu.h>

#include <linux/smp.h>

#include <linux/list.h>

#include <linux/vmalloc.h>

#include <linux/rtnetlink.h>

#include <net/icmp.h>

#include <net/ipv6.h>

#include <net/protocol.h>

#include <linux/ipv6.h>

#include <linux/icmpv6.h>

#include <linux/mutex.h>

static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,

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

{

	__be32 spi;

	struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;

	struct ip_comp_hdr *ipcomph =

		(struct ip_comp_hdr *)(skb->data + offset);

	struct xfrm_state *x;

	if (type != ICMPV6_DEST_UNREACH && type != ICMPV6_PKT_TOOBIG)

		return;

	spi = htonl(ntohs(ipcomph->cpi));

	if (!x)

		return;

	xfrm_state_put(x);

}

static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)

{

	struct xfrm_state *t = NULL;

	if (!t)

		goto out;

	t->id.proto = IPPROTO_IPV6;

	t->id.spi = xfrm6_tunnel_alloc_spi((xfrm_address_t *)&x->props.saddr);

	if (!t->id.spi)

		goto error;

	memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));

	memcpy(&t->sel, &x->sel, sizeof(t->sel));

	t->props.family = AF_INET6;

	t->props.mode = x->props.mode;

	memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));

	if (xfrm_init_state(t))

		goto error;

	atomic_set(&t->tunnel_users, 1);

out:

	return t;

error:

	t->km.state = XFRM_STATE_DEAD;

	xfrm_state_put(t);

	t = NULL;

	goto out;

}

static int ipcomp6_tunnel_attach(struct xfrm_state *x)

{

	int err = 0;

	struct xfrm_state *t = NULL;

	__be32 spi;

	spi = xfrm6_tunnel_spi_lookup((xfrm_address_t *)&x->props.saddr);

	if (spi)

					      spi, IPPROTO_IPV6, AF_INET6);

	if (!t) {

		t = ipcomp6_tunnel_create(x);

		if (!t) {

			err = -EINVAL;

			goto out;

		}

		xfrm_state_insert(t);

		xfrm_state_hold(t);

	}

	x->tunnel = t;

	atomic_inc(&t->tunnel_users);

out:

	return err;

}

static int ipcomp6_init_state(struct xfrm_state *x)

{

	int err = -EINVAL;

	x->props.header_len = 0;

	switch (x->props.mode) {

	case XFRM_MODE_TRANSPORT:

		break;

	case XFRM_MODE_TUNNEL:

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

		break;

	default:

		goto out;

	}

	err = ipcomp_init_state(x);

	if (err)

		goto out;

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

		err = ipcomp6_tunnel_attach(x);

		if (err)

			goto error_tunnel;

	}

	err = 0;

out:

	return err;

error_tunnel:

	ipcomp_destroy(x);

	goto out;

}

static const struct xfrm_type ipcomp6_type =

{

	.description	= "IPCOMP6",

	.owner		= THIS_MODULE,

	.proto		= IPPROTO_COMP,

	.init_state	= ipcomp6_init_state,

	.destructor	= ipcomp_destroy,

	.input		= ipcomp_input,

	.output		= ipcomp_output,

	.hdr_offset	= xfrm6_find_1stfragopt,

};

static struct inet6_protocol ipcomp6_protocol =

{

	.handler	= xfrm6_rcv,

	.err_handler	= ipcomp6_err,

	.flags		= INET6_PROTO_NOPOLICY,

};

static int __init ipcomp6_init(void)

{

	if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {

		printk(KERN_INFO "ipcomp6 init: can't add xfrm type\n");

		return -EAGAIN;

	}

	if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {

		printk(KERN_INFO "ipcomp6 init: can't add protocol\n");

		xfrm_unregister_type(&ipcomp6_type, AF_INET6);

		return -EAGAIN;

	}

	return 0;

}

static void __exit ipcomp6_fini(void)

{

	if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)

		printk(KERN_INFO "ipv6 ipcomp close: can't remove protocol\n");

	if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)

		printk(KERN_INFO "ipv6 ipcomp close: can't remove xfrm type\n");

}

module_init(ipcomp6_init);

module_exit(ipcomp6_fini);

MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");

MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");

MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);