1 /* dummy.c: a dummy net driver
3 The purpose of this driver is to provide a device to point a
4 route through, but not to actually transmit packets.
6 Why? If you have a machine whose only connection is an occasional
7 PPP/SLIP/PLIP link, you can only connect to your own hostname
8 when the link is up. Otherwise you have to use localhost.
9 This isn't very consistent.
11 One solution is to set up a dummy link using PPP/SLIP/PLIP,
12 but this seems (to me) too much overhead for too little gain.
13 This driver provides a small alternative. Thus you can do
15 [when not running slip]
16 ifconfig dummy slip.addr.ess.here up
21 This was written by looking at Donald Becker's skeleton driver
22 and the loopback driver. I then threw away anything that didn't
23 apply! Thanks to Alan Cox for the key clue on what to do with
26 Nick Holloway, 27th May 1994
27 [I tweaked this explanation a little but that's all]
28 Alan Cox, 30th May 1994
31 /* To have statistics (just packets sent) define this */
33 #include <linux/config.h>
34 #include <linux/module.h>
35 #include <linux/kernel.h>
36 #include <linux/netdevice.h>
37 #include <linux/init.h>
39 static int dummy_xmit(struct sk_buff *skb, struct net_device *dev);
40 static struct net_device_stats *dummy_get_stats(struct net_device *dev);
42 /* fake multicast ability */
43 static void set_multicast_list(struct net_device *dev)
47 #ifdef CONFIG_NET_FASTROUTE
48 static int dummy_accept_fastpath(struct net_device *dev, struct dst_entry *dst)
54 static int __init dummy_init(struct net_device *dev)
56 /* Initialize the device structure. */
58 dev->priv = kmalloc(sizeof(struct net_device_stats), GFP_KERNEL);
59 if (dev->priv == NULL)
61 memset(dev->priv, 0, sizeof(struct net_device_stats));
63 dev->get_stats = dummy_get_stats;
64 dev->hard_start_xmit = dummy_xmit;
65 dev->set_multicast_list = set_multicast_list;
66 #ifdef CONFIG_NET_FASTROUTE
67 dev->accept_fastpath = dummy_accept_fastpath;
70 /* Fill in device structure with ethernet-generic values. */
72 dev->tx_queue_len = 0;
73 dev->flags |= IFF_NOARP;
74 dev->flags &= ~IFF_MULTICAST;
79 static int dummy_xmit(struct sk_buff *skb, struct net_device *dev)
81 struct net_device_stats *stats = dev->priv;
84 stats->tx_bytes+=skb->len;
90 static struct net_device_stats *dummy_get_stats(struct net_device *dev)
95 static struct net_device dev_dummy;
97 static int __init dummy_init_module(void)
101 dev_dummy.init = dummy_init;
102 SET_MODULE_OWNER(&dev_dummy);
104 /* Find a name for this unit */
105 err=dev_alloc_name(&dev_dummy,"dummy%d");
108 err = register_netdev(&dev_dummy);
114 static void __exit dummy_cleanup_module(void)
116 unregister_netdev(&dev_dummy);
117 kfree(dev_dummy.priv);
119 memset(&dev_dummy, 0, sizeof(dev_dummy));
120 dev_dummy.init = dummy_init;
123 module_init(dummy_init_module);
124 module_exit(dummy_cleanup_module);
125 MODULE_LICENSE("GPL");