c

#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 = %#hx \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);
	}

//	dev = first_net_device(&init_net);
//	while (dev) {
		dev->rx_handler = old_func_ptr;
//		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);