blob: 8ebd7d78940569054f5bab34b28b3db4e2c4eeae [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* dummy.c: a dummy net driver
2
3 The purpose of this driver is to provide a device to point a
4 route through, but not to actually transmit packets.
5
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.
10
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
Jeff Garzik6aa20a22006-09-13 13:24:59 -040014
Linus Torvalds1da177e2005-04-16 15:20:36 -070015 [when not running slip]
16 ifconfig dummy slip.addr.ess.here up
17 [to go to slip]
18 ifconfig dummy down
19 dip whatever
20
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
24 misguided packets.
25
26 Nick Holloway, 27th May 1994
27 [I tweaked this explanation a little but that's all]
28 Alan Cox, 30th May 1994
29*/
30
Linus Torvalds1da177e2005-04-16 15:20:36 -070031#include <linux/module.h>
32#include <linux/kernel.h>
33#include <linux/netdevice.h>
34#include <linux/etherdevice.h>
35#include <linux/init.h>
36#include <linux/moduleparam.h>
Patrick McHardy206c9fb2007-06-13 12:04:20 -070037#include <linux/rtnetlink.h>
Patrick McHardy5d5cb172007-06-13 12:04:34 -070038#include <net/rtnetlink.h>
Patrick McHardy206c9fb2007-06-13 12:04:20 -070039
Linus Torvalds1da177e2005-04-16 15:20:36 -070040static int numdummies = 1;
41
42static int dummy_xmit(struct sk_buff *skb, struct net_device *dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
44static int dummy_set_address(struct net_device *dev, void *p)
45{
46 struct sockaddr *sa = p;
47
Jeff Garzik6aa20a22006-09-13 13:24:59 -040048 if (!is_valid_ether_addr(sa->sa_data))
Linus Torvalds1da177e2005-04-16 15:20:36 -070049 return -EADDRNOTAVAIL;
Jeff Garzik6aa20a22006-09-13 13:24:59 -040050
Linus Torvalds1da177e2005-04-16 15:20:36 -070051 memcpy(dev->dev_addr, sa->sa_data, ETH_ALEN);
52 return 0;
53}
54
55/* fake multicast ability */
56static void set_multicast_list(struct net_device *dev)
57{
58}
59
Stephen Hemmingeraa18e9e2008-11-20 20:28:00 -080060static const struct net_device_ops dummy_netdev_ops = {
61 .ndo_start_xmit = dummy_xmit,
62 .ndo_validate_addr = eth_validate_addr,
63 .ndo_set_multicast_list = set_multicast_list,
64 .ndo_set_mac_address = dummy_set_address,
65};
66
Patrick McHardy5d5cb172007-06-13 12:04:34 -070067static void dummy_setup(struct net_device *dev)
Linus Torvalds1da177e2005-04-16 15:20:36 -070068{
Stephen Hemmingeraa18e9e2008-11-20 20:28:00 -080069 ether_setup(dev);
70
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 /* Initialize the device structure. */
Stephen Hemmingeraa18e9e2008-11-20 20:28:00 -080072 dev->netdev_ops = &dummy_netdev_ops;
Patrick McHardy5d5cb172007-06-13 12:04:34 -070073 dev->destructor = free_netdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -070074
75 /* Fill in device structure with ethernet-generic values. */
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 dev->tx_queue_len = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -070077 dev->flags |= IFF_NOARP;
78 dev->flags &= ~IFF_MULTICAST;
Linus Torvalds1da177e2005-04-16 15:20:36 -070079 random_ether_addr(dev->dev_addr);
80}
81
82static int dummy_xmit(struct sk_buff *skb, struct net_device *dev)
83{
Patrick McHardy58651b22007-06-13 12:04:06 -070084 dev->stats.tx_packets++;
85 dev->stats.tx_bytes += skb->len;
Linus Torvalds1da177e2005-04-16 15:20:36 -070086
87 dev_kfree_skb(skb);
88 return 0;
89}
90
Patrick McHardy0e068772007-07-11 19:42:31 -070091static int dummy_validate(struct nlattr *tb[], struct nlattr *data[])
92{
93 if (tb[IFLA_ADDRESS]) {
94 if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
95 return -EINVAL;
96 if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
97 return -EADDRNOTAVAIL;
98 }
99 return 0;
100}
101
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700102static struct rtnl_link_ops dummy_link_ops __read_mostly = {
103 .kind = "dummy",
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700104 .setup = dummy_setup,
Patrick McHardy0e068772007-07-11 19:42:31 -0700105 .validate = dummy_validate,
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700106};
107
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108/* Number of dummy devices to be set up by this module. */
109module_param(numdummies, int, 0);
110MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices");
111
Patrick McHardy206c9fb2007-06-13 12:04:20 -0700112static int __init dummy_init_one(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113{
114 struct net_device *dev_dummy;
115 int err;
116
Patrick McHardy2d85cba2007-07-11 19:42:13 -0700117 dev_dummy = alloc_netdev(0, "dummy%d", dummy_setup);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 if (!dev_dummy)
119 return -ENOMEM;
120
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700121 err = dev_alloc_name(dev_dummy, dev_dummy->name);
122 if (err < 0)
123 goto err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700125 dev_dummy->rtnl_link_ops = &dummy_link_ops;
126 err = register_netdevice(dev_dummy);
127 if (err < 0)
128 goto err;
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700129 return 0;
130
131err:
132 free_netdev(dev_dummy);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 return err;
134}
135
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136static int __init dummy_init_module(void)
Jeff Garzik6aa20a22006-09-13 13:24:59 -0400137{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 int i, err = 0;
Patrick McHardy206c9fb2007-06-13 12:04:20 -0700139
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700140 rtnl_lock();
141 err = __rtnl_link_register(&dummy_link_ops);
142
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 for (i = 0; i < numdummies && !err; i++)
Patrick McHardy206c9fb2007-06-13 12:04:20 -0700144 err = dummy_init_one();
Patrick McHardy2d85cba2007-07-11 19:42:13 -0700145 if (err < 0)
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700146 __rtnl_link_unregister(&dummy_link_ops);
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700147 rtnl_unlock();
148
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 return err;
Jeff Garzik6aa20a22006-09-13 13:24:59 -0400150}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151
152static void __exit dummy_cleanup_module(void)
153{
Patrick McHardy2d85cba2007-07-11 19:42:13 -0700154 rtnl_link_unregister(&dummy_link_ops);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155}
156
157module_init(dummy_init_module);
158module_exit(dummy_cleanup_module);
159MODULE_LICENSE("GPL");
Patrick McHardy5d5cb172007-06-13 12:04:34 -0700160MODULE_ALIAS_RTNL_LINK("dummy");