#ifndef __LINUX_NETFILTER_H
  #define __LINUX_NETFILTER_H

  #include <linux/init.h>

  #include <linux/skbuff.h>
  #include <linux/net.h>
  #include <linux/if.h>

  #include <linux/in.h>
  #include <linux/in6.h>

  #include <linux/wait.h>
  #include <linux/list.h>

  #include <linux/static_key.h>

  #include <linux/netfilter_defs.h>

  #include <linux/netdevice.h>
  #include <net/net_namespace.h>

  #ifdef CONFIG_NETFILTER

  static inline int NF_DROP_GETERR(int verdict)
  {
  	return -(verdict >> NF_VERDICT_QBITS);
  }

  static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
  				   const union nf_inet_addr *a2)
  {
  	return a1->all[0] == a2->all[0] &&
  	       a1->all[1] == a2->all[1] &&
  	       a1->all[2] == a2->all[2] &&
  	       a1->all[3] == a2->all[3];
  }

  static inline void nf_inet_addr_mask(const union nf_inet_addr *a1,
  				     union nf_inet_addr *result,
  				     const union nf_inet_addr *mask)
  {
  	result->all[0] = a1->all[0] & mask->all[0];
  	result->all[1] = a1->all[1] & mask->all[1];
  	result->all[2] = a1->all[2] & mask->all[2];
  	result->all[3] = a1->all[3] & mask->all[3];
  }

  int netfilter_init(void);

  struct sk_buff;

  struct nf_hook_ops;

  struct sock;

  struct nf_hook_state {
  	unsigned int hook;
  	int thresh;
  	u_int8_t pf;
  	struct net_device *in;
  	struct net_device *out;

  	struct sock *sk;

  	struct list_head *hook_list;

  	int (*okfn)(struct sock *, struct sk_buff *);

  };

  static inline void nf_hook_state_init(struct nf_hook_state *p,

  				      struct list_head *hook_list,

  				      unsigned int hook,
  				      int thresh, u_int8_t pf,
  				      struct net_device *indev,
  				      struct net_device *outdev,

  				      struct sock *sk,

  				      int (*okfn)(struct sock *, struct sk_buff *))

  {
  	p->hook = hook;
  	p->thresh = thresh;
  	p->pf = pf;
  	p->in = indev;
  	p->out = outdev;

  	p->sk = sk;

  	p->hook_list = hook_list;

  	p->okfn = okfn;
  }

  typedef unsigned int nf_hookfn(const struct nf_hook_ops *ops,

  			       struct sk_buff *skb,

  			       const struct nf_hook_state *state);

  struct nf_hook_ops {

  	struct list_head 	list;

  
  	/* User fills in from here down. */

  	nf_hookfn		*hook;

  	struct net_device	*dev;

  	struct module		*owner;
  	void			*priv;
  	u_int8_t		pf;
  	unsigned int		hooknum;

  	/* Hooks are ordered in ascending priority. */

  	int			priority;

  };

  struct nf_sockopt_ops {

  	struct list_head list;

  	u_int8_t pf;

  
  	/* Non-inclusive ranges: use 0/0/NULL to never get called. */
  	int set_optmin;
  	int set_optmax;
  	int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);

  #ifdef CONFIG_COMPAT

  	int (*compat_set)(struct sock *sk, int optval,
  			void __user *user, unsigned int len);

  #endif

  	int get_optmin;
  	int get_optmax;
  	int (*get)(struct sock *sk, int optval, void __user *user, int *len);

  #ifdef CONFIG_COMPAT

  	int (*compat_get)(struct sock *sk, int optval,
  			void __user *user, int *len);

  #endif

  	/* Use the module struct to lock set/get code in place */
  	struct module *owner;

  };

  /* Function to register/unregister hook points. */

  int nf_register_net_hook(struct net *net, const struct nf_hook_ops *ops);
  void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *ops);
  int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg,
  			  unsigned int n);
  void nf_unregister_net_hooks(struct net *net, const struct nf_hook_ops *reg,
  			     unsigned int n);

  int nf_register_hook(struct nf_hook_ops *reg);
  void nf_unregister_hook(struct nf_hook_ops *reg);

  int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
  void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);

  
  /* Functions to register get/setsockopt ranges (non-inclusive).  You
     need to check permissions yourself! */
  int nf_register_sockopt(struct nf_sockopt_ops *reg);
  void nf_unregister_sockopt(struct nf_sockopt_ops *reg);

  #ifdef HAVE_JUMP_LABEL

  extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];

  static inline bool nf_hook_list_active(struct list_head *nf_hook_list,
  				       u_int8_t pf, unsigned int hook)

  {
  	if (__builtin_constant_p(pf) &&
  	    __builtin_constant_p(hook))

  		return static_key_false(&nf_hooks_needed[pf][hook]);

  	return !list_empty(nf_hook_list);

  }
  #else

  static inline bool nf_hook_list_active(struct list_head *nf_hook_list,
  				       u_int8_t pf, unsigned int hook)

  {

  	return !list_empty(nf_hook_list);

  }
  #endif

  int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state);

  
  /**
   *	nf_hook_thresh - call a netfilter hook

   *

   *	Returns 1 if the hook has allowed the packet to pass.  The function
   *	okfn must be invoked by the caller in this case.  Any other return
   *	value indicates the packet has been consumed by the hook.
   */

  static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,

  				 struct sock *sk,

  				 struct sk_buff *skb,

  				 struct net_device *indev,
  				 struct net_device *outdev,

  				 int (*okfn)(struct sock *, struct sk_buff *),
  				 int thresh)

  {

  	struct net *net = dev_net(indev ? indev : outdev);
  	struct list_head *nf_hook_list = &net->nf.hooks[pf][hook];

  
  	if (nf_hook_list_active(nf_hook_list, pf, hook)) {

  		struct nf_hook_state state;

  		nf_hook_state_init(&state, nf_hook_list, hook, thresh,

  				   pf, indev, outdev, sk, okfn);

  		return nf_hook_slow(skb, &state);
  	}

  	return 1;

  }

  static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sock *sk,
  			  struct sk_buff *skb, struct net_device *indev,
  			  struct net_device *outdev,
  			  int (*okfn)(struct sock *, struct sk_buff *))

  {

  	return nf_hook_thresh(pf, hook, sk, skb, indev, outdev, okfn, INT_MIN);

  }

                     
  /* Activate hook; either okfn or kfree_skb called, unless a hook
     returns NF_STOLEN (in which case, it's up to the hook to deal with
     the consequences).
  
     Returns -ERRNO if packet dropped.  Zero means queued, stolen or
     accepted.
  */
  
  /* RR:
     > I don't want nf_hook to return anything because people might forget
     > about async and trust the return value to mean "packet was ok".
  
     AK:
     Just document it clearly, then you can expect some sense from kernel
     coders :)
  */

  static inline int

  NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sock *sk,
  	       struct sk_buff *skb, struct net_device *in,
  	       struct net_device *out,
  	       int (*okfn)(struct sock *, struct sk_buff *), int thresh)

  {

  	int ret = nf_hook_thresh(pf, hook, sk, skb, in, out, okfn, thresh);

  	if (ret == 1)

  		ret = okfn(sk, skb);

  	return ret;
  }

  static inline int

  NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sock *sk,
  	     struct sk_buff *skb, struct net_device *in, struct net_device *out,
  	     int (*okfn)(struct sock *, struct sk_buff *), bool cond)

  {

  	int ret;
  
  	if (!cond ||

  	    ((ret = nf_hook_thresh(pf, hook, sk, skb, in, out, okfn, INT_MIN)) == 1))
  		ret = okfn(sk, skb);

  	return ret;
  }

  static inline int

  NF_HOOK(uint8_t pf, unsigned int hook, struct sock *sk, struct sk_buff *skb,

  	struct net_device *in, struct net_device *out,

  	int (*okfn)(struct sock *, struct sk_buff *))

  {

  	return NF_HOOK_THRESH(pf, hook, sk, skb, in, out, okfn, INT_MIN);

  }

  
  /* Call setsockopt() */

  int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,

  		  unsigned int len);

  int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,

  		  int *len);

  #ifdef CONFIG_COMPAT

  int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,

  		char __user *opt, unsigned int len);

  int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,

  		char __user *opt, int *len);

  #endif

  /* Call this before modifying an existing packet: ensures it is
     modifiable and linear to the point you care about (writable_len).
     Returns true or false. */

  int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);

  struct flowi;

  struct nf_queue_entry;

  struct nf_afinfo {
  	unsigned short	family;

  	__sum16		(*checksum)(struct sk_buff *skb, unsigned int hook,

  				    unsigned int dataoff, u_int8_t protocol);

  	__sum16		(*checksum_partial)(struct sk_buff *skb,
  					    unsigned int hook,
  					    unsigned int dataoff,
  					    unsigned int len,
  					    u_int8_t protocol);

  	int		(*route)(struct net *net, struct dst_entry **dst,

  				 struct flowi *fl, bool strict);

  	void		(*saveroute)(const struct sk_buff *skb,

  				     struct nf_queue_entry *entry);

  	int		(*reroute)(struct sk_buff *skb,

  				   const struct nf_queue_entry *entry);

  	int		route_key_size;

  };

  extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];

  static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)

  {
  	return rcu_dereference(nf_afinfo[family]);
  }

  static inline __sum16

  nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
  	    u_int8_t protocol, unsigned short family)
  {

  	const struct nf_afinfo *afinfo;

  	__sum16 csum = 0;

  
  	rcu_read_lock();
  	afinfo = nf_get_afinfo(family);
  	if (afinfo)
  		csum = afinfo->checksum(skb, hook, dataoff, protocol);
  	rcu_read_unlock();
  	return csum;
  }

  static inline __sum16
  nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
  		    unsigned int dataoff, unsigned int len,
  		    u_int8_t protocol, unsigned short family)
  {
  	const struct nf_afinfo *afinfo;
  	__sum16 csum = 0;
  
  	rcu_read_lock();
  	afinfo = nf_get_afinfo(family);
  	if (afinfo)
  		csum = afinfo->checksum_partial(skb, hook, dataoff, len,
  						protocol);
  	rcu_read_unlock();
  	return csum;
  }

  int nf_register_afinfo(const struct nf_afinfo *afinfo);
  void nf_unregister_afinfo(const struct nf_afinfo *afinfo);

  #include <net/flow.h>

  extern void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);

  
  static inline void

  nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)

  {

  #ifdef CONFIG_NF_NAT_NEEDED

  	void (*decodefn)(struct sk_buff *, struct flowi *);

  	rcu_read_lock();
  	decodefn = rcu_dereference(nf_nat_decode_session_hook);
  	if (decodefn)
  		decodefn(skb, fl);
  	rcu_read_unlock();

  #endif
  }

  #else /* !CONFIG_NETFILTER */

  #define NF_HOOK(pf, hook, sk, skb, indev, outdev, okfn) (okfn)(sk, skb)
  #define NF_HOOK_COND(pf, hook, sk, skb, indev, outdev, okfn, cond) (okfn)(sk, skb)

  static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,

  				 struct sock *sk,

  				 struct sk_buff *skb,

  				 struct net_device *indev,
  				 struct net_device *outdev,

  				 int (*okfn)(struct sock *sk, struct sk_buff *), int thresh)

  {

  	return okfn(sk, skb);

  }

  static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sock *sk,
  			  struct sk_buff *skb, struct net_device *indev,
  			  struct net_device *outdev,
  			  int (*okfn)(struct sock *, struct sk_buff *))

  {

  	return 1;

  }

  struct flowi;

  static inline void

  nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
  {
  }

  #endif /*CONFIG_NETFILTER*/

  #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)

  extern void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *) __rcu;

  void nf_ct_attach(struct sk_buff *, const struct sk_buff *);

  extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;

  
  struct nf_conn;

  enum ip_conntrack_info;

  struct nlattr;
  
  struct nfq_ct_hook {
  	size_t (*build_size)(const struct nf_conn *ct);
  	int (*build)(struct sk_buff *skb, struct nf_conn *ct);
  	int (*parse)(const struct nlattr *attr, struct nf_conn *ct);

  	int (*attach_expect)(const struct nlattr *attr, struct nf_conn *ct,
  			     u32 portid, u32 report);

  	void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,

  			   enum ip_conntrack_info ctinfo, s32 off);

  };

  extern struct nfq_ct_hook __rcu *nfq_ct_hook;

  #else
  static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
  #endif

  #endif /*__LINUX_NETFILTER_H*/