#ifndef _IPV6_H
  #define _IPV6_H

  #include <uapi/linux/ipv6.h>

  #define ipv6_optlen(p)  (((p)->hdrlen+1) << 3)

  #define ipv6_authlen(p) (((p)->hdrlen+2) << 2)

  /*
   * This structure contains configuration options per IPv6 link.
   */
  struct ipv6_devconf {
  	__s32		forwarding;
  	__s32		hop_limit;
  	__s32		mtu6;
  	__s32		accept_ra;
  	__s32		accept_redirects;
  	__s32		autoconf;
  	__s32		dad_transmits;
  	__s32		rtr_solicits;
  	__s32		rtr_solicit_interval;
  	__s32		rtr_solicit_delay;
  	__s32		force_mld_version;

  	__s32		mldv1_unsolicited_report_interval;
  	__s32		mldv2_unsolicited_report_interval;

  	__s32		use_tempaddr;
  	__s32		temp_valid_lft;
  	__s32		temp_prefered_lft;
  	__s32		regen_max_retry;
  	__s32		max_desync_factor;

  	__s32		max_addresses;

  	__s32		accept_ra_defrtr;

  	__s32		accept_ra_pinfo;

  #ifdef CONFIG_IPV6_ROUTER_PREF
  	__s32		accept_ra_rtr_pref;

  	__s32		rtr_probe_interval;

  #ifdef CONFIG_IPV6_ROUTE_INFO
  	__s32		accept_ra_rt_info_max_plen;
  #endif

  #endif

  	__s32		proxy_ndp;

  	__s32		accept_source_route;

  	__s32		accept_ra_from_local;

  #ifdef CONFIG_IPV6_OPTIMISTIC_DAD
  	__s32		optimistic_dad;

  	__s32		use_optimistic;

  #endif

  #ifdef CONFIG_IPV6_MROUTE
  	__s32		mc_forwarding;
  #endif

  	__s32		disable_ipv6;

  	__s32		accept_dad;

  	__s32		force_tllao;

  	__s32           ndisc_notify;

  	__s32		suppress_frag_ndisc;

  	__s32		accept_ra_mtu;

  	struct ipv6_stable_secret {
  		bool initialized;
  		struct in6_addr secret;
  	} stable_secret;

  	void		*sysctl;
  };

  
  struct ipv6_params {
  	__s32 disable_ipv6;
  	__s32 autoconf;
  };
  extern struct ipv6_params ipv6_defaults;

  #include <linux/icmpv6.h>

  #include <linux/tcp.h>
  #include <linux/udp.h>

  #include <net/inet_sock.h>

  static inline struct ipv6hdr *ipv6_hdr(const struct sk_buff *skb)
  {
  	return (struct ipv6hdr *)skb_network_header(skb);
  }

  static inline struct ipv6hdr *inner_ipv6_hdr(const struct sk_buff *skb)
  {
  	return (struct ipv6hdr *)skb_inner_network_header(skb);
  }

  static inline struct ipv6hdr *ipipv6_hdr(const struct sk_buff *skb)
  {

  	return (struct ipv6hdr *)skb_transport_header(skb);

  }

  /* 
     This structure contains results of exthdrs parsing
     as offsets from skb->nh.
   */
  
  struct inet6_skb_parm {
  	int			iif;

  	__be16			ra;

  	__u16			hop;
  	__u16			dst0;
  	__u16			srcrt;
  	__u16			dst1;

  	__u16			lastopt;

  	__u16			nhoff;

  	__u16			flags;

  #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)

  	__u16			dsthao;
  #endif

  	__u16			frag_max_size;

  
  #define IP6SKB_XFRM_TRANSFORMED	1

  #define IP6SKB_FORWARDED	2

  #define IP6SKB_REROUTED		4

  #define IP6SKB_ROUTERALERT	8

  #define IP6SKB_FRAGMENTED      16

  };
  
  #define IP6CB(skb)	((struct inet6_skb_parm*)((skb)->cb))

  #define IP6CBMTU(skb)	((struct ip6_mtuinfo *)((skb)->cb))

  static inline int inet6_iif(const struct sk_buff *skb)
  {
  	return IP6CB(skb)->iif;
  }

  struct tcp6_request_sock {
  	struct tcp_request_sock	  tcp6rsk_tcp;

  };

  struct ipv6_mc_socklist;
  struct ipv6_ac_socklist;
  struct ipv6_fl_socklist;

  struct inet6_cork {
  	struct ipv6_txoptions *opt;
  	u8 hop_limit;
  	u8 tclass;
  };

  /**
   * struct ipv6_pinfo - ipv6 private area
   *
   * In the struct sock hierarchy (tcp6_sock, upd6_sock, etc)
   * this _must_ be the last member, so that inet6_sk_generic
   * is able to calculate its offset from the base struct sock
   * by using the struct proto->slab_obj_size member. -acme
   */
  struct ipv6_pinfo {
  	struct in6_addr 	saddr;

  	struct in6_pktinfo	sticky_pktinfo;

  	const struct in6_addr		*daddr_cache;

  #ifdef CONFIG_IPV6_SUBTREES

  	const struct in6_addr		*saddr_cache;

  #endif

  	__be32			flow_label;

  	__u32			frag_size;

  
  	/*
  	 * Packed in 16bits.
  	 * Omit one shift by by putting the signed field at MSB.
  	 */
  #if defined(__BIG_ENDIAN_BITFIELD)
  	__s16			hop_limit:9;
  	__u16			__unused_1:7;
  #else
  	__u16			__unused_1:7;
  	__s16			hop_limit:9;
  #endif
  
  #if defined(__BIG_ENDIAN_BITFIELD)
  	/* Packed in 16bits. */
  	__s16			mcast_hops:9;
  	__u16			__unused_2:6,
  				mc_loop:1;
  #else
  	__u16			mc_loop:1,
  				__unused_2:6;
  	__s16			mcast_hops:9;
  #endif

  	int			ucast_oif;

  	int			mcast_oif;
  
  	/* pktoption flags */
  	union {
  		struct {

  			__u16	srcrt:1,
  				osrcrt:1,

  			        rxinfo:1,

  			        rxoinfo:1,

  				rxhlim:1,

  				rxohlim:1,

  				hopopts:1,

  				ohopopts:1,

  				dstopts:1,

  				odstopts:1,

                                  rxflow:1,

  				rxtclass:1,

  				rxpmtu:1,
  				rxorigdstaddr:1;
  				/* 2 bits hole */

  		} bits;

  		__u16		all;

  	} rxopt;
  
  	/* sockopt flags */

  	__u16			recverr:1,

  	                        sndflow:1,

  				repflow:1,

  				pmtudisc:3,

  				padding:1,	/* 1 bit hole */

  				srcprefs:3,	/* 001: prefer temporary address

  						 * 010: prefer public address
  						 * 100: prefer care-of address
  						 */

  				dontfrag:1,
  				autoflowlabel:1;

  	__u8			min_hopcount;

  	__u8			tclass;

  	__be32			rcv_flowinfo;

  
  	__u32			dst_cookie;

  	__u32			rx_dst_cookie;

  	struct ipv6_mc_socklist	__rcu *ipv6_mc_list;

  	struct ipv6_ac_socklist	*ipv6_ac_list;

  	struct ipv6_fl_socklist __rcu *ipv6_fl_list;

  
  	struct ipv6_txoptions	*opt;
  	struct sk_buff		*pktoptions;

  	struct sk_buff		*rxpmtu;

  	struct inet6_cork	cork;

  };
  
  /* WARNING: don't change the layout of the members in {raw,udp,tcp}6_sock! */
  struct raw6_sock {
  	/* inet_sock has to be the first member of raw6_sock */
  	struct inet_sock	inet;
  	__u32			checksum;	/* perform checksum */
  	__u32			offset;		/* checksum offset  */
  	struct icmp6_filter	filter;

  	__u32			ip6mr_table;

  	/* ipv6_pinfo has to be the last member of raw6_sock, see inet6_sk_generic */
  	struct ipv6_pinfo	inet6;
  };
  
  struct udp6_sock {
  	struct udp_sock	  udp;
  	/* ipv6_pinfo has to be the last member of udp6_sock, see inet6_sk_generic */
  	struct ipv6_pinfo inet6;
  };
  
  struct tcp6_sock {
  	struct tcp_sock	  tcp;
  	/* ipv6_pinfo has to be the last member of tcp6_sock, see inet6_sk_generic */
  	struct ipv6_pinfo inet6;
  };

  extern int inet6_sk_rebuild_header(struct sock *sk);

  struct tcp6_timewait_sock {
  	struct tcp_timewait_sock   tcp6tw_tcp;

  };

  #if IS_ENABLED(CONFIG_IPV6)

  static inline struct ipv6_pinfo * inet6_sk(const struct sock *__sk)
  {
  	return inet_sk(__sk)->pinet6;
  }
  
  static inline struct raw6_sock *raw6_sk(const struct sock *sk)
  {
  	return (struct raw6_sock *)sk;
  }
  
  static inline void inet_sk_copy_descendant(struct sock *sk_to,
  					   const struct sock *sk_from)
  {
  	int ancestor_size = sizeof(struct inet_sock);
  
  	if (sk_from->sk_family == PF_INET6)
  		ancestor_size += sizeof(struct ipv6_pinfo);
  
  	__inet_sk_copy_descendant(sk_to, sk_from, ancestor_size);
  }

  #define __ipv6_only_sock(sk)	(sk->sk_ipv6only)
  #define ipv6_only_sock(sk)	(__ipv6_only_sock(sk))

  #define ipv6_sk_rxinfo(sk)	((sk)->sk_family == PF_INET6 && \
  				 inet6_sk(sk)->rxopt.bits.rxinfo)

  static inline const struct in6_addr *inet6_rcv_saddr(const struct sock *sk)

  {

  	if (sk->sk_family == AF_INET6)
  		return &sk->sk_v6_rcv_saddr;
  	return NULL;

  }

  static inline int inet_v6_ipv6only(const struct sock *sk)

  {

  	/* ipv6only field is at same position for timewait and other sockets */
  	return ipv6_only_sock(sk);

  }

  #else
  #define __ipv6_only_sock(sk)	0
  #define ipv6_only_sock(sk)	0

  #define ipv6_sk_rxinfo(sk)	0

  
  static inline struct ipv6_pinfo * inet6_sk(const struct sock *__sk)
  {
  	return NULL;
  }

  static inline struct inet6_request_sock *
  			inet6_rsk(const struct request_sock *rsk)
  {
  	return NULL;
  }

  static inline struct raw6_sock *raw6_sk(const struct sock *sk)
  {
  	return NULL;
  }

  #define inet6_rcv_saddr(__sk)	NULL

  #define tcp_twsk_ipv6only(__sk)		0

  #define inet_v6_ipv6only(__sk)		0

  #endif /* IS_ENABLED(CONFIG_IPV6) */

  #endif /* _IPV6_H */