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, see <http://www.gnu.org/licenses/>.
19 */
20 /*
21 * Authors:
22 * Noriaki TAKAMIYA @USAGI
23 * Masahide NAKAMURA @USAGI
24 */
25
26 #include <linux/init.h>
27 #include <linux/kernel.h>
28 #include <linux/module.h>
29 #include <linux/skbuff.h>
30 #include <linux/spinlock.h>
31 #include <linux/stringify.h>
32 #include <linux/time.h>
33 #include <net/ipv6.h>
34 #include <net/xfrm.h>
35
36 /* Add route optimization header space.
37 *
38 * The IP header and mutable extension headers will be moved forward to make
39 * space for the route optimization header.
40 */
41 static int xfrm6_ro_output(struct xfrm_state *x, struct sk_buff *skb)
42 {
43 struct ipv6hdr *iph;
44 u8 *prevhdr;
45 int hdr_len;
46
47 iph = ipv6_hdr(skb);
48
49 hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
50 skb_set_mac_header(skb, (prevhdr - x->props.header_len) - skb->data);
51 skb_set_network_header(skb, -x->props.header_len);
52 skb->transport_header = skb->network_header + hdr_len;
53 __skb_pull(skb, hdr_len);
54 memmove(ipv6_hdr(skb), iph, hdr_len);
55
56 x->lastused = get_seconds();
57
58 return 0;
59 }
60
61 static struct xfrm_mode xfrm6_ro_mode = {
62 .output = xfrm6_ro_output,
63 .owner = THIS_MODULE,
64 .encap = XFRM_MODE_ROUTEOPTIMIZATION,
65 };
66
67 static int __init xfrm6_ro_init(void)
68 {
69 return xfrm_register_mode(&xfrm6_ro_mode, AF_INET6);
70 }
71
72 static void __exit xfrm6_ro_exit(void)
73 {
74 int err;
75
76 err = xfrm_unregister_mode(&xfrm6_ro_mode, AF_INET6);
77 BUG_ON(err);
78 }
79
80 module_init(xfrm6_ro_init);
81 module_exit(xfrm6_ro_exit);
82 MODULE_LICENSE("GPL");
83 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_ROUTEOPTIMIZATION);
84
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