/*

* send gratuitous arp on subscribed netdev events

*

*/

#include <linux/module.h>

#include <linux/moduleparam.h>

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/stat.h>

#include <linux/inetdevice.h>

#include <linux/netdevice.h>

#include <net/netevent.h>

#include <net/arp.h>

#include <linux/delay.h>

MODULE_VERSION ("0.0.3");

MODULE_LICENSE ("GPL");

MODULE_AUTHOR ("Sergey Viuchny <sergey@de-bs.ru>") ;

MODULE_DESCRIPTION ("Send gratuitous arp on netdev state changes");

static short int debug = 0;

/* send from every avaliable interface */

static short int send_all = 0;

/* wait for device intialization */

static int garp_delay = 100;

module_param(debug, short, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);

MODULE_PARM_DESC(debug, " [1] - log net device state changes");

module_param(garp_delay, int, S_IRUSR | S_IWUSR | S_IRGRP);

MODULE_PARM_DESC(garp_delay, " in ms, default [100]");

module_param(send_all, short, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);

MODULE_PARM_DESC(send_all,

"\n[1] - send garps from all avaliable interfaces\n\

[0] - send garp only from notificating interface (default)");

static int netdev_callback(struct notifier_block *self,

unsigned long event, void *ctx);

static struct notifier_block nb_dev = {

.notifier_call = netdev_callback

};

/* function taken from net/ipv4/devinet.c */

static void inetdev_send_gratuitous_arp(struct net_device *dev,

struct in_device *in_dev)

{

struct in_ifaddr *ifa;

for (ifa = in_dev->ifa_list; ifa;

ifa = ifa->ifa_next) {

arp_send(ARPOP_REQUEST, ETH_P_ARP,

ifa->ifa_local, dev,

ifa->ifa_local, NULL,

dev->dev_addr, NULL);

}

}

static int netdev_callback(struct notifier_block *self,

unsigned long event, void *ctx)

{

struct net_device *dev;

struct net_device *dev_n = netdev_notifier_info_to_dev(ctx);

struct in_device *in_dev;

char *lo_if = "lo";

switch (event)

{

case NETDEV_UP:

case NETDEV_CHANGE:

case NETDEV_CHANGEADDR:

case NETDEV_NOTIFY_PEERS:

in_dev = __in_dev_get_rtnl(dev_n);

if (!in_dev) {

printk(KERN_INFO "not in dev, skip\n");

break;

}

if (dev_n->operstate == IF_OPER_UP) {

msleep( garp_delay );

if (debug == 1)

printk(KERN_INFO "send gratuitous arp from [%s]\n",

dev_n->name);

inetdev_send_gratuitous_arp(dev_n, in_dev);

}

if (send_all == 1)

{

if ( strcmp(dev_n->name, lo_if) == 0){

if (debug == 1)

printk(KERN_INFO "notification from lo, skip\n");

break;

}

dev = first_net_device(&init_net);

read_lock(&dev_base_lock);

while (dev) {

if (debug == 1)

printk(KERN_INFO

"found [%s], notification from [%s]\n",

dev->name, dev_n->name);

if (dev->operstate == IF_OPER_UP) {

if (debug == 1)

printk(KERN_INFO

"[%s] type [%d] state [%d] is up\n",

dev->name, dev->type, dev->operstate);

} else {

if (debug == 1)

printk(KERN_INFO

"[%s] type [%d] state [%d] unknown oper state\n",

dev->name, dev->type, dev->operstate);

}

if (strcmp(dev->name, lo_if) == 0){

if (debug == 1)

printk(KERN_INFO "skip lo\n");

dev = next_net_device(dev);

continue;

}

in_dev = __in_dev_get_rtnl(dev);

if (!in_dev) {

if (debug == 1)

printk(KERN_INFO "not in dev\n");

dev = next_net_device(dev);

continue;

}

if (dev->operstate == IF_OPER_UP) {

inetdev_send_gratuitous_arp(dev, in_dev);

}

dev = next_net_device(dev);

}

read_unlock(&dev_base_lock);

}

break;

}

if (debug == 1)

{

switch (event)

{

case NETDEV_UP:

printk(KERN_INFO "got NETDEV_UP\n");

break;

case NETDEV_DOWN:

printk(KERN_INFO "got NETDEV_DOWN\n");

break;

case NETDEV_REBOOT:

printk(KERN_INFO "got NETDEV_REBOOT\n");

break;

case NETDEV_CHANGE:

printk(KERN_INFO "got NETDEV_CHANGE\n");

break;

case NETDEV_REGISTER:

printk(KERN_INFO "got NETDEV_REGISTER\n");

break;

case NETDEV_UNREGISTER:

printk(KERN_INFO "got NETDEV_UNREGISTER\n");

break;

case NETDEV_CHANGEMTU:

printk(KERN_INFO "got NETDEV_CHANGEMTU\n");

break;

case NETDEV_CHANGEADDR:

printk(KERN_INFO "got NETDEV_CHANGEADDR\n");

break;

case NETDEV_GOING_DOWN:

printk(KERN_INFO "got NETDEV_GOING_DOWN\n");

break;

case NETDEV_CHANGENAME:

printk(KERN_INFO "got NETDEV_CHANGENAME\n");

break;

case NETDEV_FEAT_CHANGE:

printk(KERN_INFO "got NETDEV_FEAT_CHANGE\n");

break;

case NETDEV_BONDING_FAILOVER:

printk(KERN_INFO "got NETDEV_BONDING_FAILOVER\n");

break;

case NETDEV_PRE_UP:

printk(KERN_INFO "got NETDEV_PRE_UP\n");

break;

case NETDEV_PRE_TYPE_CHANGE:

printk(KERN_INFO "got NETDEV_PRE_TYPE_CHANGE\n");

break;

case NETDEV_POST_TYPE_CHANGE:

printk(KERN_INFO "got NETDEV_POST_TYPE_CHANGE\n");

break;

case NETDEV_POST_INIT:

printk(KERN_INFO "got NETDEV_POST_INIT\n");

break;

case NETDEV_UNREGISTER_FINAL:

printk(KERN_INFO "got NETDEV_UNREGISTER_FINAL\n");

break;

case NETDEV_RELEASE:

printk(KERN_INFO "got NETDEV_RELEASE\n");

break;

case NETDEV_NOTIFY_PEERS:

printk(KERN_INFO "got NETDEV_NOTIFY_PEERS\n");

break;

case NETDEV_JOIN:

printk(KERN_INFO "got NETDEV_JOIN\n");

break;

#ifdef NETDEV_PRECHANGEMTU

case NETDEV_CHANGEUPPER:

printk(KERN_INFO "got NETDEV_CHANGEUPPER\n");

break;

case NETDEV_RESEND_IGMP:

printk(KERN_INFO "got NETDEV_RESEND_IGMP\n");

break;

case NETDEV_PRECHANGEMTU:

printk(KERN_INFO "got NETDEV_PRECHANGEMTU\n");

break;

#endif

#ifdef NETDEV_CHANGEINFODATA

case NETDEV_CHANGEINFODATA:

printk(KERN_INFO "got NETDEV_CHANGEINFODATA\n");

break;

#endif

default:

printk(KERN_INFO "got unknown NETDEV event\n");

}

}

return 0;

}

static int __init send_garp_init(void)

{

if (debug == 1)

printk(KERN_INFO "send_garp module loaded\n");

register_netdevice_notifier(&nb_dev);

return 0;

}

static void __exit send_garp_exit(void)

{

unregister_netdevice_notifier(&nb_dev);

if (debug == 1)

printk(KERN_INFO "send_garp module unloaded\n");

}

module_init(send_garp_init);

module_exit(send_garp_exit);