xfrm6_mode_ro.c

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/*
 * xfrm6_mode_ro.c - Route optimization mode for IPv6.
 *
 * Copyright (C)2003-2006 Helsinki University of Technology
 * Copyright (C)2003-2006 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:
 *  Noriaki TAKAMIYA @USAGI
 *  Masahide NAKAMURA @USAGI
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/stringify.h>
#include <linux/time.h>
#include <net/ipv6.h>
#include <net/xfrm.h>

/* Add route optimization header space.
 *
 * The IP header and mutable extension headers will be moved forward to make
 * space for the route optimization header.
 */
static int xfrm6_ro_output(struct xfrm_state *x, struct sk_buff *skb)
{
    struct ipv6hdr *iph;
    u8 *prevhdr;
    int hdr_len;

    iph = ipv6_hdr(skb);

    hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
    skb_set_mac_header(skb, (prevhdr - x->props.header_len) - skb->data);
    skb_set_network_header(skb, -x->props.header_len);
    skb->transport_header = skb->network_header + hdr_len;
    __skb_pull(skb, hdr_len);
    memmove(ipv6_hdr(skb), iph, hdr_len);

    x->lastused = get_seconds();

    return 0;
}

static struct xfrm_mode xfrm6_ro_mode = {
    .output = xfrm6_ro_output,
    .owner = THIS_MODULE,
    .encap = XFRM_MODE_ROUTEOPTIMIZATION,
};

static int __init xfrm6_ro_init(void)
{
    return xfrm_register_mode(&xfrm6_ro_mode, AF_INET6);
}

static void __exit xfrm6_ro_exit(void)
{
    int err;

    err = xfrm_unregister_mode(&xfrm6_ro_mode, AF_INET6);
    BUG_ON(err);
}

module_init(xfrm6_ro_init);
module_exit(xfrm6_ro_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_ROUTEOPTIMIZATION);