text: /*
   * 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);
  