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/kernel.h>
35 #include <linux/module.h>
36 #include <linux/sched.h>
37 #include <linux/types.h>
38 #include <linux/fcntl.h>
39 #include <linux/interrupt.h>
40 #include <linux/ptrace.h>
41 #include <linux/ioport.h>
43 #include <linux/malloc.h>
44 #include <linux/string.h>
45 #include <linux/init.h>
46 #include <asm/system.h>
47 #include <asm/bitops.h>
50 #include <linux/errno.h>
52 #include <linux/netdevice.h>
53 #include <linux/etherdevice.h>
54 #include <linux/skbuff.h>
56 static int dummy_xmit(struct sk_buff
*skb
, struct net_device
*dev
);
57 static struct net_device_stats
*dummy_get_stats(struct net_device
*dev
);
59 static int dummy_open(struct net_device
*dev
)
65 static int dummy_close(struct net_device
*dev
)
71 /* fake multicast ability */
72 static void set_multicast_list(struct net_device
*dev
)
76 #ifdef CONFIG_NET_FASTROUTE
77 static int dummy_accept_fastpath(struct net_device
*dev
, struct dst_entry
*dst
)
83 int __init
dummy_init(struct net_device
*dev
)
85 /* Initialize the device structure. */
86 dev
->hard_start_xmit
= dummy_xmit
;
88 dev
->priv
= kmalloc(sizeof(struct net_device_stats
), GFP_KERNEL
);
89 if (dev
->priv
== NULL
)
91 memset(dev
->priv
, 0, sizeof(struct net_device_stats
));
92 dev
->get_stats
= dummy_get_stats
;
94 dev
->open
= dummy_open
;
95 dev
->stop
= dummy_close
;
96 dev
->set_multicast_list
= set_multicast_list
;
98 /* Fill in the fields of the device structure with ethernet-generic values. */
100 dev
->tx_queue_len
= 0;
101 dev
->flags
|= IFF_NOARP
;
102 dev
->flags
&= ~IFF_MULTICAST
;
103 #ifdef CONFIG_NET_FASTROUTE
104 dev
->accept_fastpath
= dummy_accept_fastpath
;
110 static int dummy_xmit(struct sk_buff
*skb
, struct net_device
*dev
)
112 struct net_device_stats
*stats
;
114 stats
= (struct net_device_stats
*)dev
->priv
;
116 stats
->tx_bytes
+=skb
->len
;
122 static struct net_device_stats
*dummy_get_stats(struct net_device
*dev
)
124 struct net_device_stats
*stats
= (struct net_device_stats
*) dev
->priv
;
130 static int __init
dummy_probe(struct net_device
*dev
)
136 static struct net_device dev_dummy
= {
140 0, 0, 0, NULL
, dummy_probe
};
142 int init_module(void)
144 /* Find a name for this unit */
145 int err
=dev_alloc_name(&dev_dummy
,"dummy%d");
148 if (register_netdev(&dev_dummy
) != 0)
153 void cleanup_module(void)
155 unregister_netdev(&dev_dummy
);
156 kfree(dev_dummy
.priv
);
157 dev_dummy
.priv
= NULL
;