邻居子系统

邻居子系统

/*
 *  Neighbor Cache Entry States.
 */

#define NUD_INCOMPLETE  0x01 发包时新建条目
#define NUD_REACHABLE   0x02
#define NUD_STALE   0x04 收到ARP请求
#define NUD_DELAY   0x08
#define NUD_PROBE   0x10
#define NUD_FAILED  0x20

/* Dummy states */
#define NUD_NOARP   0x40
#define NUD_PERMANENT   0x80
#define NUD_NONE    0x00

net/ipv4/route.c
ipv4_neigh_lookup
    查找路由缓存
    ->__ipv4_neigh_lookup
        ->arp_hashfn
    ->neigh_create(&arp_tbl, pkey, dev)
        ->neigh_alloc
            ->nud_state = NUD_NONE
            ->setup_timer(&n->timer, neigh_timer_handler
        ->tbl->constructor/arp_constructor
        ->dev->netdev_ops->ndo_neigh_construct
        ->n->parms->neigh_setup
        ->neigh_hash_grow
        ->tbl->hash

ip_finish_output2
    发包
    ->dst_neigh_output