/* Add encapsulation header.
*
* In transport mode, the IP header and mutable extension headers will be moved
* forward to make space for the encapsulation header.
*
* In tunnel mode, the top IP header will be constructed per RFC 2401.
* The following fields in it shall be filled in by x->type->output:
* payload_len
*
* 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 void xfrm6_encap(struct sk_buff *skb)
{
struct dst_entry *dst = skb->dst;
struct xfrm_state *x = dst->xfrm;
struct ipv6hdr *iph, *top_iph;
int dsfield;
skb_push(skb, x->props.header_len);
iph = skb->nh.ipv6h;
if (!x->props.mode) {
u8 *prevhdr;
int hdr_len;
#ifdef CONFIG_XFRM_ENHANCEMENT
hdr_len = xfrm6_place_find(skb, &prevhdr, x->id.proto);
#else
hdr_len = ip6_find_1stfragopt(skb, &prevhdr);
#endif
skb->nh.raw = prevhdr - x->props.header_len;
skb->h.raw = skb->data + hdr_len;
memmove(skb->data, iph, hdr_len);
return;
}
skb->nh.raw = skb->data;
top_iph = skb->nh.ipv6h;
skb->nh.raw = &top_iph->nexthdr;
skb->h.ipv6h = top_iph + 1;
top_iph->version = 6;
top_iph->priority = iph->priority;
top_iph->flow_lbl[0] = iph->flow_lbl[0];
top_iph->flow_lbl[1] = iph->flow_lbl[1];
top_iph->flow_lbl[2] = iph->flow_lbl[2];
dsfield = ipv6_get_dsfield(top_iph);
dsfield = INET_ECN_encapsulate(dsfield, dsfield);
if (x->props.flags & XFRM_STATE_NOECN)
dsfield &= ~INET_ECN_MASK;
ipv6_change_dsfield(top_iph, 0, dsfield);
top_iph->nexthdr = IPPROTO_IPV6;
top_iph->hop_limit = dst_path_metric(dst, RTAX_HOPLIMIT);
ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
}
/* Add encapsulation header.
*
* In transport mode, the IP header will be moved forward to make space
* for the encapsulation header.
*
* In tunnel mode, the top IP header will be constructed per RFC 2401.
* The following fields in it shall be filled in by x->type->output:
* tot_len
* check
*
* On exit, skb->h will be set to the start of the payload to be processed
* by x->type->output and skb->nh will be set to the top IP header.
*/
static void xfrm4_encap(struct sk_buff *skb)
{
struct dst_entry *dst = skb->dst;
struct xfrm_state *x = dst->xfrm;
struct iphdr *iph, *top_iph;
iph = skb->nh.iph;
skb->h.ipiph = iph;
skb->nh.raw = skb_push(skb, x->props.header_len);
top_iph = skb->nh.iph;
if (!x->props.mode) {
skb->h.raw += iph->ihl*4;
memmove(top_iph, iph, iph->ihl*4);
return;
}
top_iph->ihl = 5;
top_iph->version = 4;
/* DS disclosed */
top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);
if (x->props.flags & XFRM_STATE_NOECN)
IP_ECN_clear(top_iph);
top_iph->frag_off = iph->frag_off & htons(IP_DF);
if (!top_iph->frag_off)
__ip_select_ident(top_iph, dst, 0);
top_iph->ttl = dst_path_metric(dst, RTAX_HOPLIMIT);
top_iph->saddr = x->props.saddr.a4;
top_iph->daddr = x->id.daddr.a4;
top_iph->protocol = IPPROTO_IPIP;
memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
}
