1/*
2 * xfrm6_mode_ro.c - Route optimization mode for IPv6.
3 *
4 * Copyright (C)2003-2006 Helsinki University of Technology
5 * Copyright (C)2003-2006 USAGI/WIDE Project
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20 */
21/*
22 * Authors:
23 *	Noriaki TAKAMIYA @USAGI
24 *	Masahide NAKAMURA @USAGI
25 */
26
27#include <linux/init.h>
28#include <linux/kernel.h>
29#include <linux/module.h>
30#include <linux/skbuff.h>
31#include <linux/stringify.h>
32#include <net/ipv6.h>
33#include <net/xfrm.h>
34
35/* Add route optimization header space.
36 *
37 * The IP header and mutable extension headers will be moved forward to make
38 * space for the route optimization header.
39 *
40 * On exit, skb->h will be set to the start of the encapsulation header to be
41 * filled in by x->type->output and skb->nh will be set to the nextheader field
42 * of the extension header directly preceding the encapsulation header, or in
43 * its absence, that of the top IP header.  The value of skb->data will always
44 * point to the top IP header.
45 */
46static int xfrm6_ro_output(struct xfrm_state *x, struct sk_buff *skb)
47{
48	struct ipv6hdr *iph;
49	u8 *prevhdr;
50	int hdr_len;
51
52	skb_push(skb, x->props.header_len);
53	iph = ipv6_hdr(skb);
54
55	hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
56	skb_set_network_header(skb,
57			       (prevhdr - x->props.header_len) - skb->data);
58	skb_set_transport_header(skb, hdr_len);
59	memmove(skb->data, iph, hdr_len);
60	return 0;
61}
62
63/*
64 * Do nothing about routing optimization header unlike IPsec.
65 */
66static int xfrm6_ro_input(struct xfrm_state *x, struct sk_buff *skb)
67{
68	return 0;
69}
70
71static struct xfrm_mode xfrm6_ro_mode = {
72	.input = xfrm6_ro_input,
73	.output = xfrm6_ro_output,
74	.owner = THIS_MODULE,
75	.encap = XFRM_MODE_ROUTEOPTIMIZATION,
76};
77
78static int __init xfrm6_ro_init(void)
79{
80	return xfrm_register_mode(&xfrm6_ro_mode, AF_INET6);
81}
82
83static void __exit xfrm6_ro_exit(void)
84{
85	int err;
86
87	err = xfrm_unregister_mode(&xfrm6_ro_mode, AF_INET6);
88	BUG_ON(err);
89}
90
91module_init(xfrm6_ro_init);
92module_exit(xfrm6_ro_exit);
93MODULE_LICENSE("GPL");
94MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_ROUTEOPTIMIZATION);
95