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 #include <linux/config.h>
32 #include <linux/module.h>
33 #include <linux/kernel.h>
34 #include <linux/netdevice.h>
35 #include <linux/etherdevice.h>
36 #include <linux/init.h>
37 #include <linux/moduleparam.h>
39 static int numdummies = 1;
41 static int dummy_xmit(struct sk_buff *skb, struct net_device *dev);
42 static struct net_device_stats *dummy_get_stats(struct net_device *dev);
44 static int dummy_set_address(struct net_device *dev, void *p)
46 struct sockaddr *sa = p;
48 if (!is_valid_ether_addr(sa->sa_data))
49 return -EADDRNOTAVAIL;
51 memcpy(dev->dev_addr, sa->sa_data, ETH_ALEN);
55 /* fake multicast ability */
56 static void set_multicast_list(struct net_device *dev)
60 #ifdef CONFIG_NET_FASTROUTE
61 static int dummy_accept_fastpath(struct net_device *dev, struct dst_entry *dst)
67 static void __init dummy_setup(struct net_device *dev)
69 /* Initialize the device structure. */
70 dev->get_stats = dummy_get_stats;
71 dev->hard_start_xmit = dummy_xmit;
72 dev->set_multicast_list = set_multicast_list;
73 dev->set_mac_address = dummy_set_address;
74 #ifdef CONFIG_NET_FASTROUTE
75 dev->accept_fastpath = dummy_accept_fastpath;
78 /* Fill in device structure with ethernet-generic values. */
80 dev->tx_queue_len = 0;
81 dev->flags |= IFF_NOARP;
82 dev->flags &= ~IFF_MULTICAST;
83 SET_MODULE_OWNER(dev);
84 random_ether_addr(dev->dev_addr);
87 static int dummy_xmit(struct sk_buff *skb, struct net_device *dev)
89 struct net_device_stats *stats = dev->priv;
92 stats->tx_bytes+=skb->len;
98 static struct net_device_stats *dummy_get_stats(struct net_device *dev)
103 static struct net_device **dummies;
105 /* Number of dummy devices to be set up by this module. */
106 module_param(numdummies, int, 0);
107 MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices");
109 static int __init dummy_init_one(int index)
111 struct net_device *dev_dummy;
114 dev_dummy = alloc_netdev(sizeof(struct net_device_stats),
115 "dummy%d", dummy_setup);
120 if ((err = register_netdev(dev_dummy))) {
121 free_netdev(dev_dummy);
124 dummies[index] = dev_dummy;
130 static void dummy_free_one(int index)
132 unregister_netdev(dummies[index]);
133 free_netdev(dummies[index]);
136 static int __init dummy_init_module(void)
139 dummies = kmalloc(numdummies * sizeof(void *), GFP_KERNEL);
142 for (i = 0; i < numdummies && !err; i++)
143 err = dummy_init_one(i);
151 static void __exit dummy_cleanup_module(void)
154 for (i = 0; i < numdummies; i++)
159 module_init(dummy_init_module);
160 module_exit(dummy_cleanup_module);
161 MODULE_LICENSE("GPL");