#ifndef __NET_IP_TUNNELS_H
  #define __NET_IP_TUNNELS_H 1
  
  #include <linux/if_tunnel.h>
  #include <linux/netdevice.h>
  #include <linux/skbuff.h>

  #include <linux/socket.h>

  #include <linux/types.h>
  #include <linux/u64_stats_sync.h>

  #include <linux/bitops.h>

  #include <net/dsfield.h>
  #include <net/gro_cells.h>
  #include <net/inet_ecn.h>

  #include <net/netns/generic.h>

  #include <net/rtnetlink.h>

  #include <net/lwtunnel.h>

  #include <net/dst_cache.h>

  
  #if IS_ENABLED(CONFIG_IPV6)
  #include <net/ipv6.h>
  #include <net/ip6_fib.h>
  #include <net/ip6_route.h>
  #endif
  
  /* Keep error state on tunnel for 30 sec */
  #define IPTUNNEL_ERR_TIMEO	(30*HZ)

  /* Used to memset ip_tunnel padding. */

  #define IP_TUNNEL_KEY_SIZE	offsetofend(struct ip_tunnel_key, tp_dst)

  /* Used to memset ipv4 address padding. */
  #define IP_TUNNEL_KEY_IPV4_PAD	offsetofend(struct ip_tunnel_key, u.ipv4.dst)
  #define IP_TUNNEL_KEY_IPV4_PAD_LEN				\
  	(FIELD_SIZEOF(struct ip_tunnel_key, u) -		\
  	 FIELD_SIZEOF(struct ip_tunnel_key, u.ipv4))

  struct ip_tunnel_key {
  	__be64			tun_id;

  	union {
  		struct {
  			__be32	src;
  			__be32	dst;
  		} ipv4;
  		struct {
  			struct in6_addr src;
  			struct in6_addr dst;
  		} ipv6;
  	} u;

  	__be16			tun_flags;

  	u8			tos;		/* TOS for IPv4, TC for IPv6 */
  	u8			ttl;		/* TTL for IPv4, HL for IPv6 */

  	__be32			label;		/* Flow Label for IPv6 */

  	__be16			tp_src;
  	__be16			tp_dst;

  };

  /* Flags for ip_tunnel_info mode. */
  #define IP_TUNNEL_INFO_TX	0x01	/* represents tx tunnel parameters */

  #define IP_TUNNEL_INFO_IPV6	0x02	/* key contains IPv6 addresses */

  /* Maximum tunnel options length. */
  #define IP_TUNNEL_OPTS_MAX					\
  	GENMASK((FIELD_SIZEOF(struct ip_tunnel_info,		\
  			      options_len) * BITS_PER_BYTE) - 1, 0)

  struct ip_tunnel_info {
  	struct ip_tunnel_key	key;

  #ifdef CONFIG_DST_CACHE
  	struct dst_cache	dst_cache;
  #endif

  	u8			options_len;

  	u8			mode;

  };

  /* 6rd prefix/relay information */
  #ifdef CONFIG_IPV6_SIT_6RD
  struct ip_tunnel_6rd_parm {
  	struct in6_addr		prefix;
  	__be32			relay_prefix;
  	u16			prefixlen;
  	u16			relay_prefixlen;
  };
  #endif

  struct ip_tunnel_encap {

  	u16			type;
  	u16			flags;

  	__be16			sport;
  	__be16			dport;
  };

  struct ip_tunnel_prl_entry {
  	struct ip_tunnel_prl_entry __rcu *next;
  	__be32				addr;
  	u16				flags;
  	struct rcu_head			rcu_head;
  };

  struct metadata_dst;

  struct ip_tunnel {
  	struct ip_tunnel __rcu	*next;
  	struct hlist_node hash_node;
  	struct net_device	*dev;

  	struct net		*net;	/* netns for packet i/o */

  	unsigned long	err_time;	/* Time when the last ICMP error
  					 * arrived */

  	int		err_count;	/* Number of arrived ICMP errors */

  
  	/* These four fields used only by GRE */

  	u32		i_seqno;	/* The last seen seqno	*/
  	u32		o_seqno;	/* The last output seqno */

  	int		tun_hlen;	/* Precalculated header length */

  	struct dst_cache dst_cache;

  	struct ip_tunnel_parm parms;

  	int		mlink;

  	int		encap_hlen;	/* Encap header length (FOU,GUE) */

  	int		hlen;		/* tun_hlen + encap_hlen */

  	struct ip_tunnel_encap encap;

  	/* for SIT */
  #ifdef CONFIG_IPV6_SIT_6RD
  	struct ip_tunnel_6rd_parm ip6rd;
  #endif
  	struct ip_tunnel_prl_entry __rcu *prl;	/* potential router list */
  	unsigned int		prl_count;	/* # of entries in PRL */
  	int			ip_tnl_net_id;
  	struct gro_cells	gro_cells;

  	bool			collect_md;

  	bool			ignore_df;

  };

  #define TUNNEL_CSUM		__cpu_to_be16(0x01)
  #define TUNNEL_ROUTING		__cpu_to_be16(0x02)
  #define TUNNEL_KEY		__cpu_to_be16(0x04)
  #define TUNNEL_SEQ		__cpu_to_be16(0x08)
  #define TUNNEL_STRICT		__cpu_to_be16(0x10)
  #define TUNNEL_REC		__cpu_to_be16(0x20)
  #define TUNNEL_VERSION		__cpu_to_be16(0x40)
  #define TUNNEL_NO_KEY		__cpu_to_be16(0x80)

  #define TUNNEL_DONT_FRAGMENT    __cpu_to_be16(0x0100)

  #define TUNNEL_OAM		__cpu_to_be16(0x0200)
  #define TUNNEL_CRIT_OPT		__cpu_to_be16(0x0400)

  #define TUNNEL_GENEVE_OPT	__cpu_to_be16(0x0800)
  #define TUNNEL_VXLAN_OPT	__cpu_to_be16(0x1000)

  #define TUNNEL_NOCACHE		__cpu_to_be16(0x2000)

  
  #define TUNNEL_OPTIONS_PRESENT	(TUNNEL_GENEVE_OPT | TUNNEL_VXLAN_OPT)

  
  struct tnl_ptk_info {
  	__be16 flags;
  	__be16 proto;
  	__be32 key;
  	__be32 seq;

  	int hdr_len;

  };
  
  #define PACKET_RCVD	0
  #define PACKET_REJECT	1

  #define PACKET_NEXT	2

  #define IP_TNL_HASH_BITS   7

  #define IP_TNL_HASH_SIZE   (1 << IP_TNL_HASH_BITS)
  
  struct ip_tunnel_net {

  	struct net_device *fb_tunnel_dev;

  	struct hlist_head tunnels[IP_TNL_HASH_SIZE];

  	struct ip_tunnel __rcu *collect_md_tun;

  };

  static inline void ip_tunnel_key_init(struct ip_tunnel_key *key,
  				      __be32 saddr, __be32 daddr,

  				      u8 tos, u8 ttl, __be32 label,

  				      __be16 tp_src, __be16 tp_dst,
  				      __be64 tun_id, __be16 tun_flags)

  {

  	key->tun_id = tun_id;
  	key->u.ipv4.src = saddr;
  	key->u.ipv4.dst = daddr;
  	memset((unsigned char *)key + IP_TUNNEL_KEY_IPV4_PAD,

  	       0, IP_TUNNEL_KEY_IPV4_PAD_LEN);

  	key->tos = tos;
  	key->ttl = ttl;

  	key->label = label;

  	key->tun_flags = tun_flags;

  
  	/* For the tunnel types on the top of IPsec, the tp_src and tp_dst of
  	 * the upper tunnel are used.
  	 * E.g: GRE over IPSEC, the tp_src and tp_port are zero.
  	 */

  	key->tp_src = tp_src;
  	key->tp_dst = tp_dst;

  
  	/* Clear struct padding. */

  	if (sizeof(*key) != IP_TUNNEL_KEY_SIZE)
  		memset((unsigned char *)key + IP_TUNNEL_KEY_SIZE,
  		       0, sizeof(*key) - IP_TUNNEL_KEY_SIZE);

  }

  static inline bool
  ip_tunnel_dst_cache_usable(const struct sk_buff *skb,
  			   const struct ip_tunnel_info *info)
  {
  	if (skb->mark)
  		return false;
  	if (!info)
  		return true;
  	if (info->key.tun_flags & TUNNEL_NOCACHE)
  		return false;
  
  	return true;
  }

  static inline unsigned short ip_tunnel_info_af(const struct ip_tunnel_info
  					       *tun_info)
  {
  	return tun_info->mode & IP_TUNNEL_INFO_IPV6 ? AF_INET6 : AF_INET;
  }

  static inline __be64 key32_to_tunnel_id(__be32 key)
  {
  #ifdef __BIG_ENDIAN
  	return (__force __be64)key;
  #else
  	return (__force __be64)((__force u64)key << 32);
  #endif
  }
  
  /* Returns the least-significant 32 bits of a __be64. */
  static inline __be32 tunnel_id_to_key32(__be64 tun_id)
  {
  #ifdef __BIG_ENDIAN
  	return (__force __be32)tun_id;
  #else
  	return (__force __be32)((__force u64)tun_id >> 32);
  #endif
  }

  #ifdef CONFIG_INET

  int ip_tunnel_init(struct net_device *dev);
  void ip_tunnel_uninit(struct net_device *dev);
  void  ip_tunnel_dellink(struct net_device *dev, struct list_head *head);

  struct net *ip_tunnel_get_link_net(const struct net_device *dev);

  int ip_tunnel_get_iflink(const struct net_device *dev);

  int ip_tunnel_init_net(struct net *net, int ip_tnl_net_id,
  		       struct rtnl_link_ops *ops, char *devname);

  void ip_tunnel_delete_net(struct ip_tunnel_net *itn, struct rtnl_link_ops *ops);

  
  void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,

  		    const struct iphdr *tnl_params, const u8 protocol);

  void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
  		       const u8 proto);

  int ip_tunnel_ioctl(struct net_device *dev, struct ip_tunnel_parm *p, int cmd);

  int __ip_tunnel_change_mtu(struct net_device *dev, int new_mtu, bool strict);

  int ip_tunnel_change_mtu(struct net_device *dev, int new_mtu);
  
  struct rtnl_link_stats64 *ip_tunnel_get_stats64(struct net_device *dev,
  						struct rtnl_link_stats64 *tot);
  struct ip_tunnel *ip_tunnel_lookup(struct ip_tunnel_net *itn,
  				   int link, __be16 flags,
  				   __be32 remote, __be32 local,
  				   __be32 key);
  
  int ip_tunnel_rcv(struct ip_tunnel *tunnel, struct sk_buff *skb,

  		  const struct tnl_ptk_info *tpi, struct metadata_dst *tun_dst,
  		  bool log_ecn_error);

  int ip_tunnel_changelink(struct net_device *dev, struct nlattr *tb[],
  			 struct ip_tunnel_parm *p);
  int ip_tunnel_newlink(struct net_device *dev, struct nlattr *tb[],
  		      struct ip_tunnel_parm *p);
  void ip_tunnel_setup(struct net_device *dev, int net_id);

  
  struct ip_tunnel_encap_ops {
  	size_t (*encap_hlen)(struct ip_tunnel_encap *e);
  	int (*build_header)(struct sk_buff *skb, struct ip_tunnel_encap *e,
  			    u8 *protocol, struct flowi4 *fl4);
  };
  
  #define MAX_IPTUN_ENCAP_OPS 8
  
  extern const struct ip_tunnel_encap_ops __rcu *
  		iptun_encaps[MAX_IPTUN_ENCAP_OPS];
  
  int ip_tunnel_encap_add_ops(const struct ip_tunnel_encap_ops *op,
  			    unsigned int num);
  int ip_tunnel_encap_del_ops(const struct ip_tunnel_encap_ops *op,
  			    unsigned int num);

  int ip_tunnel_encap_setup(struct ip_tunnel *t,
  			  struct ip_tunnel_encap *ipencap);

  static inline int ip_encap_hlen(struct ip_tunnel_encap *e)
  {
  	const struct ip_tunnel_encap_ops *ops;
  	int hlen = -EINVAL;
  
  	if (e->type == TUNNEL_ENCAP_NONE)
  		return 0;
  
  	if (e->type >= MAX_IPTUN_ENCAP_OPS)
  		return -EINVAL;
  
  	rcu_read_lock();
  	ops = rcu_dereference(iptun_encaps[e->type]);
  	if (likely(ops && ops->encap_hlen))
  		hlen = ops->encap_hlen(e);
  	rcu_read_unlock();
  
  	return hlen;
  }
  
  static inline int ip_tunnel_encap(struct sk_buff *skb, struct ip_tunnel *t,
  				  u8 *protocol, struct flowi4 *fl4)
  {
  	const struct ip_tunnel_encap_ops *ops;
  	int ret = -EINVAL;
  
  	if (t->encap.type == TUNNEL_ENCAP_NONE)
  		return 0;
  
  	if (t->encap.type >= MAX_IPTUN_ENCAP_OPS)
  		return -EINVAL;
  
  	rcu_read_lock();
  	ops = rcu_dereference(iptun_encaps[t->encap.type]);
  	if (likely(ops && ops->build_header))
  		ret = ops->build_header(skb, &t->encap, protocol, fl4);
  	rcu_read_unlock();
  
  	return ret;
  }

  /* Extract dsfield from inner protocol */
  static inline u8 ip_tunnel_get_dsfield(const struct iphdr *iph,
  				       const struct sk_buff *skb)
  {
  	if (skb->protocol == htons(ETH_P_IP))
  		return iph->tos;
  	else if (skb->protocol == htons(ETH_P_IPV6))
  		return ipv6_get_dsfield((const struct ipv6hdr *)iph);
  	else
  		return 0;
  }
  
  /* Propogate ECN bits out */
  static inline u8 ip_tunnel_ecn_encap(u8 tos, const struct iphdr *iph,
  				     const struct sk_buff *skb)
  {
  	u8 inner = ip_tunnel_get_dsfield(iph, skb);
  
  	return INET_ECN_encapsulate(tos, inner);
  }

  int __iptunnel_pull_header(struct sk_buff *skb, int hdr_len,
  			   __be16 inner_proto, bool raw_proto, bool xnet);
  
  static inline int iptunnel_pull_header(struct sk_buff *skb, int hdr_len,
  				       __be16 inner_proto, bool xnet)
  {
  	return __iptunnel_pull_header(skb, hdr_len, inner_proto, false, xnet);
  }

  void iptunnel_xmit(struct sock *sk, struct rtable *rt, struct sk_buff *skb,
  		   __be32 src, __be32 dst, u8 proto,
  		   u8 tos, u8 ttl, __be16 df, bool xnet);

  struct metadata_dst *iptunnel_metadata_reply(struct metadata_dst *md,
  					     gfp_t flags);

  int iptunnel_handle_offloads(struct sk_buff *skb, int gso_type_mask);

  static inline int iptunnel_pull_offloads(struct sk_buff *skb)
  {
  	if (skb_is_gso(skb)) {
  		int err;
  
  		err = skb_unclone(skb, GFP_ATOMIC);
  		if (unlikely(err))
  			return err;
  		skb_shinfo(skb)->gso_type &= ~(NETIF_F_GSO_ENCAP_ALL >>
  					       NETIF_F_GSO_SHIFT);
  	}
  
  	skb->encapsulation = 0;
  	return 0;
  }

  static inline void iptunnel_xmit_stats(struct net_device *dev, int pkt_len)

  {

  	if (pkt_len > 0) {
  		struct pcpu_sw_netstats *tstats = get_cpu_ptr(dev->tstats);

  		u64_stats_update_begin(&tstats->syncp);

  		tstats->tx_bytes += pkt_len;

  		tstats->tx_packets++;
  		u64_stats_update_end(&tstats->syncp);

  		put_cpu_ptr(tstats);

  	} else {

  		struct net_device_stats *err_stats = &dev->stats;
  
  		if (pkt_len < 0) {
  			err_stats->tx_errors++;
  			err_stats->tx_aborted_errors++;
  		} else {
  			err_stats->tx_dropped++;
  		}

  	}
  }

  static inline void *ip_tunnel_info_opts(struct ip_tunnel_info *info)

  {
  	return info + 1;
  }

  static inline void ip_tunnel_info_opts_get(void *to,
  					   const struct ip_tunnel_info *info)
  {
  	memcpy(to, info + 1, info->options_len);
  }
  
  static inline void ip_tunnel_info_opts_set(struct ip_tunnel_info *info,
  					   const void *from, int len)
  {
  	memcpy(ip_tunnel_info_opts(info), from, len);
  	info->options_len = len;
  }

  static inline struct ip_tunnel_info *lwt_tun_info(struct lwtunnel_state *lwtstate)
  {
  	return (struct ip_tunnel_info *)lwtstate->data;
  }

  extern struct static_key ip_tunnel_metadata_cnt;
  
  /* Returns > 0 if metadata should be collected */
  static inline int ip_tunnel_collect_metadata(void)
  {
  	return static_key_false(&ip_tunnel_metadata_cnt);
  }

  void __init ip_tunnel_core_init(void);

  void ip_tunnel_need_metadata(void);
  void ip_tunnel_unneed_metadata(void);

  #else /* CONFIG_INET */
  
  static inline struct ip_tunnel_info *lwt_tun_info(struct lwtunnel_state *lwtstate)
  {
  	return NULL;
  }
  
  static inline void ip_tunnel_need_metadata(void)
  {
  }
  
  static inline void ip_tunnel_unneed_metadata(void)
  {
  }

  static inline void ip_tunnel_info_opts_get(void *to,
  					   const struct ip_tunnel_info *info)
  {
  }
  
  static inline void ip_tunnel_info_opts_set(struct ip_tunnel_info *info,
  					   const void *from, int len)
  {
  	info->options_len = 0;
  }

  #endif /* CONFIG_INET */

  #endif /* __NET_IP_TUNNELS_H */