root/include/net/arp.h

DEFINITIONS

1. arp_hashfn
2. __ipv4_neigh_lookup_noref
3. __ipv4_neigh_lookup

/* linux/net/inet/arp.h */
#ifndef _ARP_H
#define _ARP_H

#include <linux/if_arp.h>
#include <linux/hash.h>
#include <net/neighbour.h>


extern struct neigh_table arp_tbl;

static inline u32 arp_hashfn(u32 key, const struct net_device *dev, u32 hash_rnd)
{
        u32 val = key ^ hash32_ptr(dev);

        return val * hash_rnd;
}

static inline struct neighbour *__ipv4_neigh_lookup_noref(struct net_device *dev, u32 key)
{
        struct neigh_hash_table *nht = rcu_dereference_bh(arp_tbl.nht);
        struct neighbour *n;
        u32 hash_val;

        hash_val = arp_hashfn(key, dev, nht->hash_rnd[0]) >> (32 - nht->hash_shift);
        for (n = rcu_dereference_bh(nht->hash_buckets[hash_val]);
             n != NULL;
             n = rcu_dereference_bh(n->next)) {
                if (n->dev == dev && *(u32 *)n->primary_key == key)
                        return n;
        }

        return NULL;
}

static inline struct neighbour *__ipv4_neigh_lookup(struct net_device *dev, u32 key)
{
        struct neighbour *n;

        rcu_read_lock_bh();
        n = __ipv4_neigh_lookup_noref(dev, key);
        if (n && !atomic_inc_not_zero(&n->refcnt))
                n = NULL;
        rcu_read_unlock_bh();

        return n;
}

void arp_init(void);
int arp_find(unsigned char *haddr, struct sk_buff *skb);
int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg);
void arp_send(int type, int ptype, __be32 dest_ip,
              struct net_device *dev, __be32 src_ip,
              const unsigned char *dest_hw,
              const unsigned char *src_hw, const unsigned char *th);
int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir);
void arp_ifdown(struct net_device *dev);

struct sk_buff *arp_create(int type, int ptype, __be32 dest_ip,
                           struct net_device *dev, __be32 src_ip,
                           const unsigned char *dest_hw,
                           const unsigned char *src_hw,
                           const unsigned char *target_hw);
void arp_xmit(struct sk_buff *skb);

#endif  /* _ARP_H */