--- /dev/null
+#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