text: /*
   * INET		An implementation of the TCP/IP protocol suite for the LINUX
   *		operating system.  INET is implemented using the  BSD Socket
   *		interface as the means of communication with the user level.
   *
   *		Definitions for the UDP protocol.
   *
   * Version:	@(#)udp.h	1.0.2	04/28/93
   *
   * Author:	Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
   *
   *		This program is free software; you can redistribute it and/or
   *		modify it under the terms of the GNU General Public License
   *		as published by the Free Software Foundation; either version
   *		2 of the License, or (at your option) any later version.
   */
  #ifndef _LINUX_UDP_H
  #define _LINUX_UDP_H
  
  #include <net/inet_sock.h>
  #include <linux/skbuff.h>
  #include <net/netns/hash.h>
  #include <uapi/linux/udp.h>
  
  static inline struct udphdr *udp_hdr(const struct sk_buff *skb)
  {
  	return (struct udphdr *)skb_transport_header(skb);
  }
  
  static inline struct udphdr *inner_udp_hdr(const struct sk_buff *skb)
  {
  	return (struct udphdr *)skb_inner_transport_header(skb);
  }
  
  #define UDP_HTABLE_SIZE_MIN		(CONFIG_BASE_SMALL ? 128 : 256)
  
  static inline u32 udp_hashfn(const struct net *net, u32 num, u32 mask)
  {
  	return (num + net_hash_mix(net)) & mask;
  }
  
  struct udp_sock {
  	/* inet_sock has to be the first member */
  	struct inet_sock inet;
  #define udp_port_hash		inet.sk.__sk_common.skc_u16hashes[0]
  #define udp_portaddr_hash	inet.sk.__sk_common.skc_u16hashes[1]
  #define udp_portaddr_node	inet.sk.__sk_common.skc_portaddr_node
  	int		 pending;	/* Any pending frames ? */
  	unsigned int	 corkflag;	/* Cork is required */
  	__u8		 encap_type;	/* Is this an Encapsulation socket? */
  	unsigned char	 no_check6_tx:1,/* Send zero UDP6 checksums on TX? */
  			 no_check6_rx:1;/* Allow zero UDP6 checksums on RX? */
  	/*
  	 * Following member retains the information to create a UDP header
  	 * when the socket is uncorked.
  	 */
  	__u16		 len;		/* total length of pending frames */
  	/*
  	 * Fields specific to UDP-Lite.
  	 */
  	__u16		 pcslen;
  	__u16		 pcrlen;
  /* indicator bits used by pcflag: */
  #define UDPLITE_BIT      0x1  		/* set by udplite proto init function */
  #define UDPLITE_SEND_CC  0x2  		/* set via udplite setsockopt         */
  #define UDPLITE_RECV_CC  0x4		/* set via udplite setsocktopt        */
  	__u8		 pcflag;        /* marks socket as UDP-Lite if > 0    */
  	__u8		 unused[3];
  	/*
  	 * For encapsulation sockets.
  	 */
  	int (*encap_rcv)(struct sock *sk, struct sk_buff *skb);
  	void (*encap_destroy)(struct sock *sk);
  
  	/* GRO functions for UDP socket */
  	struct sk_buff **	(*gro_receive)(struct sock *sk,
  					       struct sk_buff **head,
  					       struct sk_buff *skb);
  	int			(*gro_complete)(struct sock *sk,
  						struct sk_buff *skb,
  						int nhoff);
  };
  
  static inline struct udp_sock *udp_sk(const struct sock *sk)
  {
  	return (struct udp_sock *)sk;
  }
  
  static inline void udp_set_no_check6_tx(struct sock *sk, bool val)
  {
  	udp_sk(sk)->no_check6_tx = val;
  }
  
  static inline void udp_set_no_check6_rx(struct sock *sk, bool val)
  {
  	udp_sk(sk)->no_check6_rx = val;
  }
  
  static inline bool udp_get_no_check6_tx(struct sock *sk)
  {
  	return udp_sk(sk)->no_check6_tx;
  }
  
  static inline bool udp_get_no_check6_rx(struct sock *sk)
  {
  	return udp_sk(sk)->no_check6_rx;
  }
  
  #define udp_portaddr_for_each_entry(__sk, list) \
  	hlist_for_each_entry(__sk, list, __sk_common.skc_portaddr_node)
  
  #define udp_portaddr_for_each_entry_rcu(__sk, list) \
  	hlist_for_each_entry_rcu(__sk, list, __sk_common.skc_portaddr_node)
  
  #define IS_UDPLITE(__sk) (udp_sk(__sk)->pcflag)
  
  #endif	/* _LINUX_UDP_H */
  