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-rw-r--r--drivers/net/dummy.c152
1 files changed, 152 insertions, 0 deletions
diff --git a/drivers/net/dummy.c b/drivers/net/dummy.c
new file mode 100644
index 00000000000..dd8c15ac5c7
--- /dev/null
+++ b/drivers/net/dummy.c
@@ -0,0 +1,152 @@
+/* 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/etherdevice.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+
+static int numdummies = 1;
+
+static int dummy_xmit(struct sk_buff *skb, struct net_device *dev);
+static struct net_device_stats *dummy_get_stats(struct net_device *dev);
+
+static int dummy_set_address(struct net_device *dev, void *p)
+{
+ struct sockaddr *sa = p;
+
+ if (!is_valid_ether_addr(sa->sa_data))
+ return -EADDRNOTAVAIL;
+
+ memcpy(dev->dev_addr, sa->sa_data, ETH_ALEN);
+ return 0;
+}
+
+/* fake multicast ability */
+static void set_multicast_list(struct net_device *dev)
+{
+}
+
+static void __init dummy_setup(struct net_device *dev)
+{
+ /* Initialize the device structure. */
+ dev->get_stats = dummy_get_stats;
+ dev->hard_start_xmit = dummy_xmit;
+ dev->set_multicast_list = set_multicast_list;
+ dev->set_mac_address = dummy_set_address;
+
+ /* Fill in device structure with ethernet-generic values. */
+ ether_setup(dev);
+ dev->tx_queue_len = 0;
+ dev->change_mtu = NULL;
+ dev->flags |= IFF_NOARP;
+ dev->flags &= ~IFF_MULTICAST;
+ SET_MODULE_OWNER(dev);
+ random_ether_addr(dev->dev_addr);
+}
+
+static int dummy_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+ struct net_device_stats *stats = netdev_priv(dev);
+
+ 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 netdev_priv(dev);
+}
+
+static struct net_device **dummies;
+
+/* Number of dummy devices to be set up by this module. */
+module_param(numdummies, int, 0);
+MODULE_PARM_DESC(numdummies, "Number of dummy pseudo devices");
+
+static int __init dummy_init_one(int index)
+{
+ struct net_device *dev_dummy;
+ int err;
+
+ dev_dummy = alloc_netdev(sizeof(struct net_device_stats),
+ "dummy%d", dummy_setup);
+
+ if (!dev_dummy)
+ return -ENOMEM;
+
+ if ((err = register_netdev(dev_dummy))) {
+ free_netdev(dev_dummy);
+ dev_dummy = NULL;
+ } else {
+ dummies[index] = dev_dummy;
+ }
+
+ return err;
+}
+
+static void dummy_free_one(int index)
+{
+ unregister_netdev(dummies[index]);
+ free_netdev(dummies[index]);
+}
+
+static int __init dummy_init_module(void)
+{
+ int i, err = 0;
+ dummies = kmalloc(numdummies * sizeof(void *), GFP_KERNEL);
+ if (!dummies)
+ return -ENOMEM;
+ for (i = 0; i < numdummies && !err; i++)
+ err = dummy_init_one(i);
+ if (err) {
+ while (--i >= 0)
+ dummy_free_one(i);
+ }
+ return err;
+}
+
+static void __exit dummy_cleanup_module(void)
+{
+ int i;
+ for (i = 0; i < numdummies; i++)
+ dummy_free_one(i);
+ kfree(dummies);
+}
+
+module_init(dummy_init_module);
+module_exit(dummy_cleanup_module);
+MODULE_LICENSE("GPL");