/*
   *		INETPEER - A storage for permanent information about peers
   *

   *  Authors:	Andrey V. Savochkin <saw@msu.ru>
   */
  
  #ifndef _NET_INETPEER_H
  #define _NET_INETPEER_H
  
  #include <linux/types.h>
  #include <linux/init.h>
  #include <linux/jiffies.h>
  #include <linux/spinlock.h>

  #include <linux/rtnetlink.h>

  #include <net/ipv6.h>

  #include <linux/atomic.h>

  struct inetpeer_addr_base {

  	union {

  		__be32			a4;
  		__be32			a6[4];

  	};

  };
  
  struct inetpeer_addr {
  	struct inetpeer_addr_base	addr;
  	__u16				family;

  };

  struct inet_peer {

  	/* group together avl_left,avl_right,v4daddr to speedup lookups */

  	struct inet_peer __rcu	*avl_left, *avl_right;

  	struct inetpeer_addr	daddr;

  	__u32			avl_height;

  
  	u32			metrics[RTAX_MAX];
  	u32			rate_tokens;	/* rate limiting for ICMP */

  	int			redirect_genid;

  	unsigned long		rate_last;
  	unsigned long		pmtu_expires;
  	u32			pmtu_orig;
  	u32			pmtu_learned;
  	struct inetpeer_addr_base redirect_learned;

  	/*
  	 * Once inet_peer is queued for deletion (refcnt == -1), following fields

  	 * are not available: rid, ip_id_count, tcp_ts, tcp_ts_stamp

  	 * We can share memory with rcu_head to help keep inet_peer small.

  	 */
  	union {
  		struct {

  			atomic_t			rid;		/* Frag reception counter */
  			atomic_t			ip_id_count;	/* IP ID for the next packet */
  			__u32				tcp_ts;
  			__u32				tcp_ts_stamp;

  		};
  		struct rcu_head         rcu;

  		struct inet_peer	*gc_next;

  	};

  
  	/* following fields might be frequently dirtied */
  	__u32			dtime;	/* the time of last use of not referenced entries */
  	atomic_t		refcnt;

  };
  
  void			inet_initpeers(void) __init;

  #define INETPEER_METRICS_NEW	(~(u32) 0)
  
  static inline bool inet_metrics_new(const struct inet_peer *p)
  {
  	return p->metrics[RTAX_LOCK-1] == INETPEER_METRICS_NEW;
  }

  /* can be called with or without local BH being disabled */

  struct inet_peer	*inet_getpeer(const struct inetpeer_addr *daddr, int create);

  
  static inline struct inet_peer *inet_getpeer_v4(__be32 v4daddr, int create)
  {

  	struct inetpeer_addr daddr;

  	daddr.addr.a4 = v4daddr;

  	daddr.family = AF_INET;
  	return inet_getpeer(&daddr, create);
  }

  static inline struct inet_peer *inet_getpeer_v6(const struct in6_addr *v6daddr, int create)

  {

  	struct inetpeer_addr daddr;

  	ipv6_addr_copy((struct in6_addr *)daddr.addr.a6, v6daddr);

  	daddr.family = AF_INET6;
  	return inet_getpeer(&daddr, create);
  }

  /* can be called from BH context or outside */

  extern void inet_putpeer(struct inet_peer *p);

  extern bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout);

  /*
   * temporary check to make sure we dont access rid, ip_id_count, tcp_ts,
   * tcp_ts_stamp if no refcount is taken on inet_peer
   */
  static inline void inet_peer_refcheck(const struct inet_peer *p)
  {
  	WARN_ON_ONCE(atomic_read(&p->refcnt) <= 0);
  }

  /* can be called with or without local BH being disabled */

  static inline int inet_getid(struct inet_peer *p, int more)

  {

  	int old, new;

  	more++;

  	inet_peer_refcheck(p);

  	do {
  		old = atomic_read(&p->ip_id_count);
  		new = old + more;
  		if (!new)
  			new = 1;
  	} while (atomic_cmpxchg(&p->ip_id_count, old, new) != old);
  	return new;

  }
  
  #endif /* _NET_INETPEER_H */