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. */
57 dev
->hard_start_xmit
= dummy_xmit
;
59 dev
->priv
= kmalloc(sizeof(struct net_device_stats
), GFP_KERNEL
);
60 if (dev
->priv
== NULL
)
62 memset(dev
->priv
, 0, sizeof(struct net_device_stats
));
63 dev
->get_stats
= dummy_get_stats
;
65 dev
->set_multicast_list
= set_multicast_list
;
67 /* Fill in the fields of the device structure with ethernet-generic values. */
69 dev
->tx_queue_len
= 0;
70 dev
->flags
|= IFF_NOARP
;
71 dev
->flags
&= ~IFF_MULTICAST
;
72 #ifdef CONFIG_NET_FASTROUTE
73 dev
->accept_fastpath
= dummy_accept_fastpath
;
79 static int dummy_xmit(struct sk_buff
*skb
, struct net_device
*dev
)
81 struct net_device_stats
*stats
;
83 stats
= (struct net_device_stats
*)dev
->priv
;
85 stats
->tx_bytes
+=skb
->len
;
91 static struct net_device_stats
*dummy_get_stats(struct net_device
*dev
)
96 static struct net_device dev_dummy
;
98 static int __init
dummy_init_module(void)
102 dev_dummy
.init
= dummy_init
;
103 SET_MODULE_OWNER(&dev_dummy
);
105 /* Find a name for this unit */
106 err
=dev_alloc_name(&dev_dummy
,"dummy%d");
109 if (register_netdev(&dev_dummy
) != 0)
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
);