| /* dummy.c: a dummy net driver |
| |
| The purpose of this driver is to provide a device to point a |
| route through, but not to actually transmit packets. |
| |
| Why? If you have a machine whose only connection is an occasional |
| PPP/SLIP/PLIP link, you can only connect to your own hostname |
| when the link is up. Otherwise you have to use localhost. |
| This isn't very consistent. |
| |
| One solution is to set up a dummy link using PPP/SLIP/PLIP, |
| but this seems (to me) too much overhead for too little gain. |
| This driver provides a small alternative. Thus you can do |
| |
| [when not running slip] |
| ifconfig dummy slip.addr.ess.here up |
| [to go to slip] |
| ifconfig dummy down |
| dip whatever |
| |
| This was written by looking at Donald Becker's skeleton driver |
| and the loopback driver. I then threw away anything that didn't |
| apply! Thanks to Alan Cox for the key clue on what to do with |
| misguided packets. |
| |
| Nick Holloway, 27th May 1994 |
| [I tweaked this explanation a little but that's all] |
| Alan Cox, 30th May 1994 |
| */ |
| |
| #include <linux/config.h> |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| #include <linux/netdevice.h> |
| #include <linux/init.h> |
| |
| static int dummy_xmit(struct sk_buff *skb, struct net_device *dev); |
| static struct net_device_stats *dummy_get_stats(struct net_device *dev); |
| |
| /* fake multicast ability */ |
| static void set_multicast_list(struct net_device *dev) |
| { |
| } |
| |
| #ifdef CONFIG_NET_FASTROUTE |
| static int dummy_accept_fastpath(struct net_device *dev, struct dst_entry *dst) |
| { |
| return -1; |
| } |
| #endif |
| |
| static int __init dummy_init(struct net_device *dev) |
| { |
| /* Initialize the device structure. */ |
| |
| dev->priv = kmalloc(sizeof(struct net_device_stats), GFP_KERNEL); |
| if (dev->priv == NULL) |
| return -ENOMEM; |
| memset(dev->priv, 0, sizeof(struct net_device_stats)); |
| |
| dev->get_stats = dummy_get_stats; |
| dev->hard_start_xmit = dummy_xmit; |
| dev->set_multicast_list = set_multicast_list; |
| #ifdef CONFIG_NET_FASTROUTE |
| dev->accept_fastpath = dummy_accept_fastpath; |
| #endif |
| |
| /* Fill in device structure with ethernet-generic values. */ |
| ether_setup(dev); |
| dev->tx_queue_len = 0; |
| dev->flags |= IFF_NOARP; |
| dev->flags &= ~IFF_MULTICAST; |
| |
| return 0; |
| } |
| |
| static int dummy_xmit(struct sk_buff *skb, struct net_device *dev) |
| { |
| struct net_device_stats *stats = dev->priv; |
| |
| stats->tx_packets++; |
| stats->tx_bytes+=skb->len; |
| |
| dev_kfree_skb(skb); |
| return 0; |
| } |
| |
| static struct net_device_stats *dummy_get_stats(struct net_device *dev) |
| { |
| return dev->priv; |
| } |
| |
| static struct net_device dev_dummy; |
| |
| static int __init dummy_init_module(void) |
| { |
| int err; |
| |
| dev_dummy.init = dummy_init; |
| SET_MODULE_OWNER(&dev_dummy); |
| |
| /* Find a name for this unit */ |
| err=dev_alloc_name(&dev_dummy,"dummy%d"); |
| if(err<0) |
| return err; |
| err = register_netdev(&dev_dummy); |
| if (err<0) |
| return err; |
| return 0; |
| } |
| |
| static void __exit dummy_cleanup_module(void) |
| { |
| unregister_netdev(&dev_dummy); |
| kfree(dev_dummy.priv); |
| |
| memset(&dev_dummy, 0, sizeof(dev_dummy)); |
| dev_dummy.init = dummy_init; |
| } |
| |
| module_init(dummy_init_module); |
| module_exit(dummy_cleanup_module); |
| MODULE_LICENSE("GPL"); |