#ifndef __NET_UDP_TUNNEL_H
  #define __NET_UDP_TUNNEL_H

  #include <net/ip_tunnels.h>
  #include <net/udp.h>
  
  #if IS_ENABLED(CONFIG_IPV6)
  #include <net/ipv6.h>
  #include <net/addrconf.h>
  #endif

  struct udp_port_cfg {
  	u8			family;
  
  	/* Used only for kernel-created sockets */
  	union {
  		struct in_addr		local_ip;
  #if IS_ENABLED(CONFIG_IPV6)
  		struct in6_addr		local_ip6;
  #endif
  	};
  
  	union {
  		struct in_addr		peer_ip;
  #if IS_ENABLED(CONFIG_IPV6)
  		struct in6_addr		peer_ip6;
  #endif
  	};
  
  	__be16			local_udp_port;
  	__be16			peer_udp_port;
  	unsigned int		use_udp_checksums:1,
  				use_udp6_tx_checksums:1,

  				use_udp6_rx_checksums:1,
  				ipv6_v6only:1;

  };

  int udp_sock_create4(struct net *net, struct udp_port_cfg *cfg,
  		     struct socket **sockp);
  
  #if IS_ENABLED(CONFIG_IPV6)
  int udp_sock_create6(struct net *net, struct udp_port_cfg *cfg,
  		     struct socket **sockp);
  #else
  static inline int udp_sock_create6(struct net *net, struct udp_port_cfg *cfg,
  				   struct socket **sockp)
  {
  	return 0;
  }
  #endif
  
  static inline int udp_sock_create(struct net *net,
  				  struct udp_port_cfg *cfg,
  				  struct socket **sockp)
  {
  	if (cfg->family == AF_INET)
  		return udp_sock_create4(net, cfg, sockp);
  
  	if (cfg->family == AF_INET6)
  		return udp_sock_create6(net, cfg, sockp);
  
  	return -EPFNOSUPPORT;
  }

  typedef int (*udp_tunnel_encap_rcv_t)(struct sock *sk, struct sk_buff *skb);
  typedef void (*udp_tunnel_encap_destroy_t)(struct sock *sk);

  typedef struct sk_buff **(*udp_tunnel_gro_receive_t)(struct sock *sk,
  						     struct sk_buff **head,
  						     struct sk_buff *skb);
  typedef int (*udp_tunnel_gro_complete_t)(struct sock *sk, struct sk_buff *skb,
  					 int nhoff);

  
  struct udp_tunnel_sock_cfg {
  	void *sk_user_data;     /* user data used by encap_rcv call back */
  	/* Used for setting up udp_sock fields, see udp.h for details */
  	__u8  encap_type;
  	udp_tunnel_encap_rcv_t encap_rcv;
  	udp_tunnel_encap_destroy_t encap_destroy;

  	udp_tunnel_gro_receive_t gro_receive;
  	udp_tunnel_gro_complete_t gro_complete;

  };
  
  /* Setup the given (UDP) sock to receive UDP encapsulated packets */
  void setup_udp_tunnel_sock(struct net *net, struct socket *sock,
  			   struct udp_tunnel_sock_cfg *sock_cfg);

  /* -- List of parsable UDP tunnel types --
   *
   * Adding to this list will result in serious debate.  The main issue is
   * that this list is essentially a list of workarounds for either poorly
   * designed tunnels, or poorly designed device offloads.
   *
   * The parsing supported via these types should really be used for Rx
   * traffic only as the network stack will have already inserted offsets for
   * the location of the headers in the skb.  In addition any ports that are
   * pushed should be kept within the namespace without leaking to other
   * devices such as VFs or other ports on the same device.
   *
   * It is strongly encouraged to use CHECKSUM_COMPLETE for Rx to avoid the
   * need to use this for Rx checksum offload.  It should not be necessary to
   * call this function to perform Tx offloads on outgoing traffic.
   */
  enum udp_parsable_tunnel_type {
  	UDP_TUNNEL_TYPE_VXLAN,		/* RFC 7348 */
  	UDP_TUNNEL_TYPE_GENEVE,		/* draft-ietf-nvo3-geneve */

  	UDP_TUNNEL_TYPE_VXLAN_GPE,	/* draft-ietf-nvo3-vxlan-gpe */

  };
  
  struct udp_tunnel_info {
  	unsigned short type;
  	sa_family_t sa_family;
  	__be16 port;
  };
  
  /* Notify network devices of offloadable types */
  void udp_tunnel_push_rx_port(struct net_device *dev, struct socket *sock,
  			     unsigned short type);
  void udp_tunnel_notify_add_rx_port(struct socket *sock, unsigned short type);
  void udp_tunnel_notify_del_rx_port(struct socket *sock, unsigned short type);

  static inline void udp_tunnel_get_rx_info(struct net_device *dev)
  {
  	ASSERT_RTNL();
  	call_netdevice_notifiers(NETDEV_UDP_TUNNEL_PUSH_INFO, dev);
  }

  /* Transmit the skb using UDP encapsulation. */

  void udp_tunnel_xmit_skb(struct rtable *rt, struct sock *sk, struct sk_buff *skb,
  			 __be32 src, __be32 dst, __u8 tos, __u8 ttl,
  			 __be16 df, __be16 src_port, __be16 dst_port,
  			 bool xnet, bool nocheck);

  
  #if IS_ENABLED(CONFIG_IPV6)

  int udp_tunnel6_xmit_skb(struct dst_entry *dst, struct sock *sk,
  			 struct sk_buff *skb,

  			 struct net_device *dev, struct in6_addr *saddr,
  			 struct in6_addr *daddr,

  			 __u8 prio, __u8 ttl, __be32 label,
  			 __be16 src_port, __be16 dst_port, bool nocheck);

  #endif
  
  void udp_tunnel_sock_release(struct socket *sock);

  struct metadata_dst *udp_tun_rx_dst(struct sk_buff *skb, unsigned short family,
  				    __be16 flags, __be64 tunnel_id,
  				    int md_size);

  #ifdef CONFIG_INET

  static inline int udp_tunnel_handle_offloads(struct sk_buff *skb, bool udp_csum)

  {
  	int type = udp_csum ? SKB_GSO_UDP_TUNNEL_CSUM : SKB_GSO_UDP_TUNNEL;

  	return iptunnel_handle_offloads(skb, type);

  }

  #endif

  
  static inline void udp_tunnel_encap_enable(struct socket *sock)
  {
  #if IS_ENABLED(CONFIG_IPV6)
  	if (sock->sk->sk_family == PF_INET6)
  		ipv6_stub->udpv6_encap_enable();
  	else
  #endif
  		udp_encap_enable();
  }

  #endif