1. 根目录:
2. include
3. net
4. neighbour.h

#ifndef _NET_NEIGHBOUR_H
#define _NET_NEIGHBOUR_H

#include <linux/neighbour.h>

/*
 *	Generic neighbour manipulation
 *
 *	Authors:
 *	Pedro Roque		<roque@di.fc.ul.pt>
 *	Alexey Kuznetsov	<kuznet@ms2.inr.ac.ru>
 *
 * 	Changes:
 *
 *	Harald Welte:		<laforge@gnumonks.org>
 *		- Add neighbour cache statistics like rtstat
 */

#include <linux/atomic.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/rcupdate.h>
#include <linux/seq_file.h>

#include <linux/err.h>
#include <linux/sysctl.h>
#include <linux/workqueue.h>
#include <net/rtnetlink.h>

/*
 * NUD stands for "neighbor unreachability detection"
 */

#define NUD_IN_TIMER	(NUD_INCOMPLETE|NUD_REACHABLE|NUD_DELAY|NUD_PROBE)
#define NUD_VALID	(NUD_PERMANENT|NUD_NOARP|NUD_REACHABLE|NUD_PROBE|NUD_STALE|NUD_DELAY)
#define NUD_CONNECTED	(NUD_PERMANENT|NUD_NOARP|NUD_REACHABLE)

struct neighbour;

struct neigh_parms {
#ifdef CONFIG_NET_NS
	struct net *net;
#endif
	struct net_device *dev;
	struct neigh_parms *next;
	int	(*neigh_setup)(struct neighbour *);
	void	(*neigh_cleanup)(struct neighbour *);
	struct neigh_table *tbl;

	void	*sysctl_table;

	int dead;
	atomic_t refcnt;
	struct rcu_head rcu_head;

	int	base_reachable_time;
	int	retrans_time;
	int	gc_staletime;
	int	reachable_time;
	int	delay_probe_time;

	int	queue_len_bytes;
	int	ucast_probes;
	int	app_probes;
	int	mcast_probes;
	int	anycast_delay;
	int	proxy_delay;
	int	proxy_qlen;
	int	locktime;
};

struct neigh_statistics {
	unsigned long allocs;		/* number of allocated neighs */
	unsigned long destroys;		/* number of destroyed neighs */
	unsigned long hash_grows;	/* number of hash resizes */

	unsigned long res_failed;	/* number of failed resolutions */

	unsigned long lookups;		/* number of lookups */
	unsigned long hits;		/* number of hits (among lookups) */

	unsigned long rcv_probes_mcast;	/* number of received mcast ipv6 */
	unsigned long rcv_probes_ucast; /* number of received ucast ipv6 */

	unsigned long periodic_gc_runs;	/* number of periodic GC runs */
	unsigned long forced_gc_runs;	/* number of forced GC runs */

	unsigned long unres_discards;	/* number of unresolved drops */
};

#define NEIGH_CACHE_STAT_INC(tbl, field) this_cpu_inc((tbl)->stats->field)

struct neighbour {
	struct neighbour __rcu	*next;
	struct neigh_table	*tbl;
	struct neigh_parms	*parms;
	unsigned long		confirmed;
	unsigned long		updated;
	rwlock_t		lock;
	atomic_t		refcnt;
	struct sk_buff_head	arp_queue;
	unsigned int		arp_queue_len_bytes;
	struct timer_list	timer;
	unsigned long		used;
	atomic_t		probes;
	__u8			flags;
	__u8			nud_state;
	__u8			type;
	__u8			dead;
	seqlock_t		ha_lock;
	unsigned char		ha[ALIGN(MAX_ADDR_LEN, sizeof(unsigned long))];
	struct hh_cache		hh;
	int			(*output)(struct neighbour *, struct sk_buff *);
	const struct neigh_ops	*ops;
	struct rcu_head		rcu;
	struct net_device	*dev;
	u8			primary_key[0];
};

struct neigh_ops {
	int			family;
	void			(*solicit)(struct neighbour *, struct sk_buff *);
	void			(*error_report)(struct neighbour *, struct sk_buff *);
	int			(*output)(struct neighbour *, struct sk_buff *);
	int			(*connected_output)(struct neighbour *, struct sk_buff *);
};

struct pneigh_entry {
	struct pneigh_entry	*next;
#ifdef CONFIG_NET_NS
	struct net		*net;
#endif
	struct net_device	*dev;
	u8			flags;
	u8			key[0];
};

/*
 *	neighbour table manipulation
 */

#define NEIGH_NUM_HASH_RND	4

struct neigh_hash_table {
	struct neighbour __rcu	**hash_buckets;
	unsigned int		hash_shift;
	__u32			hash_rnd[NEIGH_NUM_HASH_RND];
	struct rcu_head		rcu;
};


struct neigh_table {
	struct neigh_table	*next;
	int			family;
	int			entry_size;
	int			key_len;
	__u32			(*hash)(const void *pkey,
					const struct net_device *dev,
					__u32 *hash_rnd);
	int			(*constructor)(struct neighbour *);
	int			(*pconstructor)(struct pneigh_entry *);
	void			(*pdestructor)(struct pneigh_entry *);
	void			(*proxy_redo)(struct sk_buff *skb);
	char			*id;
	struct neigh_parms	parms;
	/* HACK. gc_* should follow parms without a gap! */
	int			gc_interval;
	int			gc_thresh1;
	int			gc_thresh2;
	int			gc_thresh3;
	unsigned long		last_flush;
	struct delayed_work	gc_work;
	struct timer_list 	proxy_timer;
	struct sk_buff_head	proxy_queue;
	atomic_t		entries;
	rwlock_t		lock;
	unsigned long		last_rand;
	struct neigh_statistics	__percpu *stats;
	struct neigh_hash_table __rcu *nht;
	struct pneigh_entry	**phash_buckets;
};

#define NEIGH_PRIV_ALIGN	sizeof(long long)
#define NEIGH_ENTRY_SIZE(size)	ALIGN((size), NEIGH_PRIV_ALIGN)

static inline void *neighbour_priv(const struct neighbour *n)
{
	return (char *)n + n->tbl->entry_size;
}

/* flags for neigh_update() */
#define NEIGH_UPDATE_F_OVERRIDE			0x00000001
#define NEIGH_UPDATE_F_WEAK_OVERRIDE		0x00000002
#define NEIGH_UPDATE_F_OVERRIDE_ISROUTER	0x00000004
#define NEIGH_UPDATE_F_ISROUTER			0x40000000
#define NEIGH_UPDATE_F_ADMIN			0x80000000

extern void			neigh_table_init(struct neigh_table *tbl);
extern int			neigh_table_clear(struct neigh_table *tbl);
extern struct neighbour *	neigh_lookup(struct neigh_table *tbl,
					     const void *pkey,
					     struct net_device *dev);
extern struct neighbour *	neigh_lookup_nodev(struct neigh_table *tbl,
						   struct net *net,
						   const void *pkey);
extern struct neighbour *	__neigh_create(struct neigh_table *tbl,
					       const void *pkey,
					       struct net_device *dev,
					       bool want_ref);
static inline struct neighbour *neigh_create(struct neigh_table *tbl,
					     const void *pkey,
					     struct net_device *dev)
{
	return __neigh_create(tbl, pkey, dev, true);
}
extern void			neigh_destroy(struct neighbour *neigh);
extern int			__neigh_event_send(struct neighbour *neigh, struct sk_buff *skb);
extern int			neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new, 
					     u32 flags);
extern void			neigh_changeaddr(struct neigh_table *tbl, struct net_device *dev);
extern int			neigh_ifdown(struct neigh_table *tbl, struct net_device *dev);
extern int			neigh_resolve_output(struct neighbour *neigh, struct sk_buff *skb);
extern int			neigh_connected_output(struct neighbour *neigh, struct sk_buff *skb);
extern int			neigh_compat_output(struct neighbour *neigh, struct sk_buff *skb);
extern int			neigh_direct_output(struct neighbour *neigh, struct sk_buff *skb);
extern struct neighbour 	*neigh_event_ns(struct neigh_table *tbl,
						u8 *lladdr, void *saddr,
						struct net_device *dev);

extern struct neigh_parms	*neigh_parms_alloc(struct net_device *dev, struct neigh_table *tbl);
extern void			neigh_parms_release(struct neigh_table *tbl, struct neigh_parms *parms);

static inline
struct net			*neigh_parms_net(const struct neigh_parms *parms)
{
	return read_pnet(&parms->net);
}

extern unsigned long		neigh_rand_reach_time(unsigned long base);

extern void			pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
					       struct sk_buff *skb);
extern struct pneigh_entry	*pneigh_lookup(struct neigh_table *tbl, struct net *net, const void *key, struct net_device *dev, int creat);
extern struct pneigh_entry	*__pneigh_lookup(struct neigh_table *tbl,
						 struct net *net,
						 const void *key,
						 struct net_device *dev);
extern int			pneigh_delete(struct neigh_table *tbl, struct net *net, const void *key, struct net_device *dev);

static inline
struct net			*pneigh_net(const struct pneigh_entry *pneigh)
{
	return read_pnet(&pneigh->net);
}

extern void neigh_app_ns(struct neighbour *n);
extern void neigh_for_each(struct neigh_table *tbl, void (*cb)(struct neighbour *, void *), void *cookie);
extern void __neigh_for_each_release(struct neigh_table *tbl, int (*cb)(struct neighbour *));
extern void pneigh_for_each(struct neigh_table *tbl, void (*cb)(struct pneigh_entry *));

struct neigh_seq_state {
	struct seq_net_private p;
	struct neigh_table *tbl;
	struct neigh_hash_table *nht;
	void *(*neigh_sub_iter)(struct neigh_seq_state *state,
				struct neighbour *n, loff_t *pos);
	unsigned int bucket;
	unsigned int flags;
#define NEIGH_SEQ_NEIGH_ONLY	0x00000001
#define NEIGH_SEQ_IS_PNEIGH	0x00000002
#define NEIGH_SEQ_SKIP_NOARP	0x00000004
};
extern void *neigh_seq_start(struct seq_file *, loff_t *, struct neigh_table *, unsigned int);
extern void *neigh_seq_next(struct seq_file *, void *, loff_t *);
extern void neigh_seq_stop(struct seq_file *, void *);

extern int			neigh_sysctl_register(struct net_device *dev, 
						      struct neigh_parms *p,
						      char *p_name,
						      proc_handler *proc_handler);
extern void			neigh_sysctl_unregister(struct neigh_parms *p);

static inline void __neigh_parms_put(struct neigh_parms *parms)
{
	atomic_dec(&parms->refcnt);
}

static inline struct neigh_parms *neigh_parms_clone(struct neigh_parms *parms)
{
	atomic_inc(&parms->refcnt);
	return parms;
}

/*
 *	Neighbour references
 */

static inline void neigh_release(struct neighbour *neigh)
{
	if (atomic_dec_and_test(&neigh->refcnt))
		neigh_destroy(neigh);
}

static inline struct neighbour * neigh_clone(struct neighbour *neigh)
{
	if (neigh)
		atomic_inc(&neigh->refcnt);
	return neigh;
}

#define neigh_hold(n)	atomic_inc(&(n)->refcnt)

static inline int neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
{
	unsigned long now = jiffies;
	
	if (neigh->used != now)
		neigh->used = now;
	if (!(neigh->nud_state&(NUD_CONNECTED|NUD_DELAY|NUD_PROBE)))
		return __neigh_event_send(neigh, skb);
	return 0;
}

#ifdef CONFIG_BRIDGE_NETFILTER
static inline int neigh_hh_bridge(struct hh_cache *hh, struct sk_buff *skb)
{
	unsigned int seq, hh_alen;

	do {
		seq = read_seqbegin(&hh->hh_lock);
		hh_alen = HH_DATA_ALIGN(ETH_HLEN);
		memcpy(skb->data - hh_alen, hh->hh_data, ETH_ALEN + hh_alen - ETH_HLEN);
	} while (read_seqretry(&hh->hh_lock, seq));
	return 0;
}
#endif

static inline int neigh_hh_output(const struct hh_cache *hh, struct sk_buff *skb)
{
	unsigned int seq;
	int hh_len;

	do {
		seq = read_seqbegin(&hh->hh_lock);
		hh_len = hh->hh_len;
		if (likely(hh_len <= HH_DATA_MOD)) {
			/* this is inlined by gcc */
			memcpy(skb->data - HH_DATA_MOD, hh->hh_data, HH_DATA_MOD);
		} else {
			int hh_alen = HH_DATA_ALIGN(hh_len);

			memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
		}
	} while (read_seqretry(&hh->hh_lock, seq));

	skb_push(skb, hh_len);
	return dev_queue_xmit(skb);
}

static inline struct neighbour *
__neigh_lookup(struct neigh_table *tbl, const void *pkey, struct net_device *dev, int creat)
{
	struct neighbour *n = neigh_lookup(tbl, pkey, dev);

	if (n || !creat)
		return n;

	n = neigh_create(tbl, pkey, dev);
	return IS_ERR(n) ? NULL : n;
}

static inline struct neighbour *
__neigh_lookup_errno(struct neigh_table *tbl, const void *pkey,
  struct net_device *dev)
{
	struct neighbour *n = neigh_lookup(tbl, pkey, dev);

	if (n)
		return n;

	return neigh_create(tbl, pkey, dev);
}

struct neighbour_cb {
	unsigned long sched_next;
	unsigned int flags;
};

#define LOCALLY_ENQUEUED 0x1

#define NEIGH_CB(skb)	((struct neighbour_cb *)(skb)->cb)

static inline void neigh_ha_snapshot(char *dst, const struct neighbour *n,
				     const struct net_device *dev)
{
	unsigned int seq;

	do {
		seq = read_seqbegin(&n->ha_lock);
		memcpy(dst, n->ha, dev->addr_len);
	} while (read_seqretry(&n->ha_lock, seq));
}
#endif