#ifndef LKH_HOOK_H
#define LKH_HOOK_H

static DEFINE_MUTEX(lkh_hook_mutex);

#define MAX_HOOK_COUNT		1024

/* 多核信息同步处理 */
#define lkh_entry_dereference(e) rcu_dereference_protected(e, lockdep_is_held(&lkh_hook_mutex))

/* 执行HOOK处理后的返回值 */
#define LKH_DROP 0
#define LKH_ACCEPT 1
#define LKH_STOLEN 2
#define LKH_QUEUE 3
#define LKH_REPEAT 4
#define LKH_STOP 5	/* Deprecated, for userspace nf_queue compatibility. */

/* 钩子函数调用位置 */
enum lkh_inet_hooks 
{
    LKH_INET_PRE_FORWARD,
    LKH_INET_NUMHOOKS
};


/* 支持的协议类型 */
enum 
{
    LKH_PROTO_UNSPEC =  0,
    LKH_PROTO_IPV4   =  1,
    LKH_PROTO_IPV6   =  2,
    LKH_PROTO_NUMPROTO,
};

struct lkh_hook_entries_rcu_head 
{
    struct rcu_head head;
    void *allocation;
};

struct lkh_hook_state 
{
    unsigned int hook_stage;
    u_int8_t pf;
    struct net_device *in;
    struct net_device *out;
    struct sock *sk;
    struct net *net;
};

typedef unsigned int lkh_hookfn(void *priv, struct sk_buff *skb, const struct lkh_hook_state *state);

struct lkh_hook_ops 
{
    /* User fills in from here down. */
    lkh_hookfn		*hook;          /*  钩子函数 */
    void			*priv;
    u_int8_t		pf;             /* 协议类型 IPv4、IPv6、brigde等 */
    unsigned int		hook_stage;    /* 阶段ID，比如PRE_FORWARD等*/
    int			priority;          /* 优先级 */
};
				   
struct lkh_hook_entry 
{
    lkh_hookfn			*hook;
    void				*priv;
};

/* 一种协议类型的hook集合，包括多个处理阶段 */
struct lkh_hook_entries 
{
    u_int8_t				num_hook_entries;
    struct lkh_hook_entry		hooks[];
};
				  
struct lkh_hook
{
    struct list_head list;
    void * net_ptr;          /* 记录struct net 结构指针，用来查找对应的hook */
    struct lkh_hook_entries __rcu *hooks_ipv4[LKH_INET_NUMHOOKS];
    struct lkh_hook_entries __rcu *hooks_ipv6[LKH_INET_NUMHOOKS];
};


/* 句柄 */
struct lkh_hook_handle 
{
    struct list_head list;
    unsigned int net_num;                 /* 网络命名空间数量 */
};

extern struct lkh_hook_handle g_lkh_hook_handle;
extern void lkh_hash_struct_show(void);
extern int lkh_register_net_hooks(struct net *net, const struct lkh_hook_ops *reg, unsigned int hookcount);
extern void lkh_unregister_net_hooks(struct net *net, const struct lkh_hook_ops *reg, unsigned int hookcount);
extern int lkh_hook(u_int8_t pf, 
				 unsigned int hook_stage, 
				 struct net *net,
				 struct sock *sk, 
				 struct sk_buff *skb,
				 struct net_device *indev, 
				 struct net_device *outdev);

#endif