neighbour.h

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#ifndef _NET_NEIGHBOUR_H
#define _NET_NEIGHBOUR_H

#include <linux/neighbour.h>

/*
 *  Generic neighbour manipulation
 *
 *  Authors:
 *  Pedro Roque     <[email protected]>
 *  Alexey Kuznetsov    <[email protected]>
 *
 *  Changes:
 *
 *  Harald Welte:       <[email protected]>
 *      - 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)

static inline void *neighbour_priv(const struct neighbour *n)
{
    return (char *)n + ALIGN(sizeof(*n) + n->tbl->key_len, NEIGH_PRIV_ALIGN);
}

/* 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