1. 根目录:
2. include
3. net
4. fou.h

#ifndef __NET_FOU_H
#define __NET_FOU_H

#include <linux/skbuff.h>

#include <net/flow.h>
#include <net/gue.h>
#include <net/ip_tunnels.h>
#include <net/udp.h>

size_t fou_encap_hlen(struct ip_tunnel_encap *e);
static size_t gue_encap_hlen(struct ip_tunnel_encap *e);

int fou_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
		     u8 *protocol, struct flowi4 *fl4);
int gue_build_header(struct sk_buff *skb, struct ip_tunnel_encap *e,
		     u8 *protocol, struct flowi4 *fl4);

#endif