#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>

MODULE_LICENSE("GPL");

rx_handler_result_t (*old_func_ptr)(struct sk_buff **);


rx_handler_result_t pack_handler (struct sk_buff **pskb) {

    struct sk_buff *skbuff = *pskb;

    printk (KERN_INFO "SK_BUFF_INFO: mac_len = %d", skbuff->mac_len);
    printk (KERN_INFO "proto_id = %hd \n", ntohs(skbuff->protocol));

    return RX_HANDLER_PASS;
}

static int __init mod_init (void) {

    struct net_device * dev;

    dev = first_net_device (&init_net);

    while (dev) {
//      if (dev->rx_handler != NULL) {
            old_func_ptr = dev->rx_handler;
            dev->rx_handler = pack_handler;
            printk (KERN_INFO "ptr = %p \n", old_func_ptr);
//      }

        printk (KERN_INFO "name = %s \n", dev->name);

        printk (KERN_INFO "pointer = %p \n", dev->rx_handler);


        printk (KERN_INFO "RX packets = %lu \n", dev->stats.rx_packets);
        printk (KERN_INFO "TX packets = %lu \n", dev->stats.tx_packets);
        dev = next_net_device(dev);
    }

    return 0;
}

static void  __exit mod_exit (void) {
    printk (KERN_INFO "Bye! \n");
}

module_init(mod_init);
module_exit(mod_exit);