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Commit | Line | Data |
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1da177e4 LT |
1 | /* 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 | |
6aa20a22 | 14 | |
1da177e4 LT |
15 | [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 | ||
1da177e4 LT |
31 | #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> | |
206c9fb2 | 37 | #include <linux/rtnetlink.h> |
5d5cb173 | 38 | #include <net/rtnetlink.h> |
206c9fb2 | 39 | |
1da177e4 LT |
40 | static int numdummies = 1; |
41 | ||
42 | static int dummy_xmit(struct sk_buff *skb, struct net_device *dev); | |
1da177e4 LT |
43 | |
44 | static int dummy_set_address(struct net_device *dev, void *p) | |
45 | { | |
46 | struct sockaddr *sa = p; | |
47 | ||
6aa20a22 | 48 | if (!is_valid_ether_addr(sa->sa_data)) |
1da177e4 | 49 | return -EADDRNOTAVAIL; |
6aa20a22 | 50 | |
1da177e4 LT |
51 | memcpy(dev->dev_addr, sa->sa_data, ETH_ALEN); |
52 | return 0; | |
53 | } | |
54 | ||
55 | /* fake multicast ability */ | |
56 | static void set_multicast_list(struct net_device *dev) | |
57 | { | |
58 | } | |
59 | ||
5d5cb173 | 60 | static void dummy_setup(struct net_device *dev) |
1da177e4 LT |
61 | { |
62 | /* Initialize the device structure. */ | |
1da177e4 LT |
63 | dev->hard_start_xmit = dummy_xmit; |
64 | dev->set_multicast_list = set_multicast_list; | |
65 | dev->set_mac_address = dummy_set_address; | |
5d5cb173 | 66 | dev->destructor = free_netdev; |
1da177e4 LT |
67 | |
68 | /* Fill in device structure with ethernet-generic values. */ | |
69 | ether_setup(dev); | |
70 | dev->tx_queue_len = 0; | |
71 | dev->change_mtu = NULL; | |
72 | dev->flags |= IFF_NOARP; | |
73 | dev->flags &= ~IFF_MULTICAST; | |
74 | SET_MODULE_OWNER(dev); | |
75 | random_ether_addr(dev->dev_addr); | |
76 | } | |
77 | ||
78 | static int dummy_xmit(struct sk_buff *skb, struct net_device *dev) | |
79 | { | |
58651b24 PM |
80 | dev->stats.tx_packets++; |
81 | dev->stats.tx_bytes += skb->len; | |
1da177e4 LT |
82 | |
83 | dev_kfree_skb(skb); | |
84 | return 0; | |
85 | } | |
86 | ||
5d5cb173 PM |
87 | static struct rtnl_link_ops dummy_link_ops __read_mostly = { |
88 | .kind = "dummy", | |
5d5cb173 | 89 | .setup = dummy_setup, |
5d5cb173 PM |
90 | }; |
91 | ||
1da177e4 LT |
92 | /* Number of dummy devices to be set up by this module. */ |
93 | module_param(numdummies, int, 0); | |
94 | MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices"); | |
95 | ||
206c9fb2 | 96 | static int __init dummy_init_one(void) |
1da177e4 LT |
97 | { |
98 | struct net_device *dev_dummy; | |
99 | int err; | |
100 | ||
2d85cba2 | 101 | dev_dummy = alloc_netdev(0, "dummy%d", dummy_setup); |
1da177e4 LT |
102 | if (!dev_dummy) |
103 | return -ENOMEM; | |
104 | ||
5d5cb173 PM |
105 | err = dev_alloc_name(dev_dummy, dev_dummy->name); |
106 | if (err < 0) | |
107 | goto err; | |
1da177e4 | 108 | |
5d5cb173 PM |
109 | dev_dummy->rtnl_link_ops = &dummy_link_ops; |
110 | err = register_netdevice(dev_dummy); | |
111 | if (err < 0) | |
112 | goto err; | |
5d5cb173 | 113 | return 0; |
206c9fb2 | 114 | |
5d5cb173 PM |
115 | err: |
116 | free_netdev(dev_dummy); | |
117 | return err; | |
6aa20a22 | 118 | } |
1da177e4 LT |
119 | |
120 | static int __init dummy_init_module(void) | |
6aa20a22 | 121 | { |
1da177e4 | 122 | int i, err = 0; |
206c9fb2 | 123 | |
5d5cb173 PM |
124 | rtnl_lock(); |
125 | err = __rtnl_link_register(&dummy_link_ops); | |
126 | ||
1da177e4 | 127 | for (i = 0; i < numdummies && !err; i++) |
206c9fb2 | 128 | err = dummy_init_one(); |
2d85cba2 | 129 | if (err < 0) |
5d5cb173 | 130 | __rtnl_link_unregister(&dummy_link_ops); |
5d5cb173 PM |
131 | rtnl_unlock(); |
132 | ||
1da177e4 | 133 | return err; |
6aa20a22 | 134 | } |
1da177e4 LT |
135 | |
136 | static void __exit dummy_cleanup_module(void) | |
137 | { | |
2d85cba2 | 138 | rtnl_link_unregister(&dummy_link_ops); |
1da177e4 LT |
139 | } |
140 | ||
141 | module_init(dummy_init_module); | |
142 | module_exit(dummy_cleanup_module); | |
143 | MODULE_LICENSE("GPL"); | |
5d5cb173 | 144 | MODULE_ALIAS_RTNL_LINK("dummy"); |