ip_iptfs_hdr
struct ip_iptfs_hdr *ipth;
ipth = (struct ip_iptfs_hdr *)&iptcch;
struct ip_iptfs_hdr *h;
remaining = mtu - (skb->len - sizeof(struct ip_iptfs_hdr));
x->props.header_len += sizeof(struct iphdr) + sizeof(struct ip_iptfs_hdr);
x->props.header_len += sizeof(struct ipv6hdr) + sizeof(struct ip_iptfs_hdr);
x->props.enc_hdr_len = sizeof(struct ip_iptfs_hdr);