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/*
* xfrm6_mode_transport.c - Transport mode encapsulation for IPv6.
*
* Copyright (C) 2002 USAGI/WIDE Project
* Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/stringify.h>
#include <net/dst.h>
#include <net/ipv6.h>
#include <net/xfrm.h>
/* Add encapsulation header.
*
* The IP header and mutable extension headers will be moved forward to make
* space for the encapsulation header.
*
* On exit, skb->h will be set to the start of the encapsulation header to be
* filled in by x->type->output and skb->nh will be set to the nextheader field
* of the extension header directly preceding the encapsulation header, or in
* its absence, that of the top IP header. The value of skb->data will always
* point to the top IP header.
*/
static int xfrm6_transport_output(struct sk_buff *skb)
{
struct xfrm_state *x = skb->dst->xfrm;
struct ipv6hdr *iph;
u8 *prevhdr;
int hdr_len;
skb_push(skb, x->props.header_len);
iph = skb->nh.ipv6h;
hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
skb->nh.raw = prevhdr - x->props.header_len;
skb->h.raw = skb->data + hdr_len;
memmove(skb->data, iph, hdr_len);
return 0;
}
/* Remove encapsulation header.
*
* The IP header will be moved over the top of the encapsulation header.
*
* On entry, skb->h shall point to where the IP header should be and skb->nh
* shall be set to where the IP header currently is. skb->data shall point
* to the start of the payload.
*/
static int xfrm6_transport_input(struct xfrm_state *x, struct sk_buff *skb)
{
int ihl = skb->data - skb->h.raw;
if (skb->h.raw != skb->nh.raw)
skb->nh.raw = memmove(skb->h.raw, skb->nh.raw, ihl);
skb->nh.ipv6h->payload_len = htons(skb->len + ihl -
sizeof(struct ipv6hdr));
skb->h.raw = skb->data;
return 0;
}
static struct xfrm_mode xfrm6_transport_mode = {
.input = xfrm6_transport_input,
.output = xfrm6_transport_output,
.owner = THIS_MODULE,
.encap = XFRM_MODE_TRANSPORT,
};
static int __init xfrm6_transport_init(void)
{
return xfrm_register_mode(&xfrm6_transport_mode, AF_INET6);
}
static void __exit xfrm6_transport_exit(void)
{
int err;
err = xfrm_unregister_mode(&xfrm6_transport_mode, AF_INET6);
BUG_ON(err);
}
module_init(xfrm6_transport_init);
module_exit(xfrm6_transport_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TRANSPORT);
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