打印默认网关

#include <linux/init.h>
#include <net/net_namespace.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/spinlock_types.h>
#include <net/ip_fib.h>

#define TABLE_LOCAL_INDEX 0
#define TABLE_MAIN_INDEX 1

MODULE_LICENSE( "Dual BSD/GPL" );
static void print_default_gw(void);
/**********************************
 * 以下结来自 net/ipv4/fib_hash.c
 *********************************/
struct fib_alias
{
    struct list_head fa_list;
        struct fib_info *fa_info;
        u8 fa_tos;
        u8 fa_type;
        u8 fa_scope;
        u8 fa_state;
        struct rcu_head rcu;
};

struct fib_node
{
        struct hlist_node fn_hash;
        struct list_head fn_alias;
        __be32 fn_key;
        struct fib_alias fn_embedded_alias;
};

struct fn_zone
{
        struct fn_zone *fz_next;
        struct hlist_head *fz_hash;
        int fz_nent;
        int fz_divisor;
        u32 fz_hashmask;
        int fz_order;
        __be32 fz_mask;
};

struct fn_hash
{
        struct fn_zone *fn_zones[33];
        struct fn_zone *fn_zone_list;
};

/**************************************************************/
static void print_default_gw(void)
{
        struct fib_table *local_table;
        struct fn_hash *fn;
        struct hlist_head *hhead;
        struct list_head *head;
        struct fib_node *f;
        struct hlist_node *node;
        struct fib_alias *fa;

        hhead = &init_net.ipv4.fib_table_hash[TABLE_LOCAL_INDEX];
        local_table = hlist_entry(hhead->first, struct fib_table, tb_hlist);
        fn = (struct fn_hash *)&local_table->tb_data[0];
        hhead = &fn->fn_zones[0]->fz_hash[0];
        hlist_for_each_entry(f, node, hhead, fn_hash)
    {
                head = (struct list_head *)&f->fn_alias;
                list_for_each_entry(fa, head, fa_list)
        {
                        struct fib_info *fi;
                        struct net_device * ndev;
                        fi = fa->fa_info;
                        ndev = fi->fib_nh[0].nh_dev;
                        printk("dev: %s \n",ndev->name);     /*打印出网卡*/
                        printk("default gw ip: %d.%d.%d.%d\n",     /*打印出默认网关*/
                                        ((unsigned char *)(&fi->fib_nh[0].nh_gw))[0], \
                                        ((unsigned char *)(&fi->fib_nh[0].nh_gw))[1], \
                                        ((unsigned char *)(&fi->fib_nh[0].nh_gw))[2], \
                                        ((unsigned char *)(&fi->fib_nh[0].nh_gw))[3]);
                }
        }
}

static int gw_init(void)
{
        print_default_gw();
        return 0;
}

static void gw_exit( void )
{
        printk( KERN_ALERT "Goodbye \n" );
}

module_init(gw_init );
module_exit(gw_exit )