--- /dev/null
+/******************************************************************************
+ * netback/loopback.c
+ *
+ * A two-interface loopback device to emulate a local netfront-netback
+ * connection. This ensures that local packet delivery looks identical
+ * to inter-domain delivery. Most importantly, packets delivered locally
+ * originating from other domains will get *copied* when they traverse this
+ * driver. This prevents unbounded delays in socket-buffer queues from
+ * causing the netback driver to "seize up".
+ *
+ * This driver creates a symmetric pair of loopback interfaces with names
+ * vif0.0 and veth0. The intention is that 'vif0.0' is bound to an Ethernet
+ * bridge, just like a proper netback interface, while a local IP interface
+ * is configured on 'veth0'.
+ *
+ * As with a real netback interface, vif0.0 is configured with a suitable
+ * dummy MAC address. No default is provided for veth0: a reasonable strategy
+ * is to transfer eth0's MAC address to veth0, and give eth0 a dummy address
+ * (to avoid confusing the Etherbridge).
+ *
+ * Copyright (c) 2005 K A Fraser
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/inetdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/skbuff.h>
+#include <linux/ethtool.h>
+#include <net/dst.h>
+
+static int nloopbacks = 8;
+module_param(nloopbacks, int, 0);
+MODULE_PARM_DESC(nloopbacks, "Number of netback-loopback devices to create");
+
+struct net_private {
+ struct net_device *loopback_dev;
+ struct net_device_stats stats;
+};
+
+static int loopback_open(struct net_device *dev)
+{
+ struct net_private *np = netdev_priv(dev);
+ memset(&np->stats, 0, sizeof(np->stats));
+ netif_start_queue(dev);
+ return 0;
+}
+
+static int loopback_close(struct net_device *dev)
+{
+ netif_stop_queue(dev);
+ return 0;
+}
+
+static int loopback_start_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+ struct net_private *np = netdev_priv(dev);
+
+ dst_release(skb->dst);
+ skb->dst = NULL;
+
+ skb_orphan(skb);
+
+ np->stats.tx_bytes += skb->len;
+ np->stats.tx_packets++;
+
+ /* Switch to loopback context. */
+ dev = np->loopback_dev;
+ np = netdev_priv(dev);
+
+ np->stats.rx_bytes += skb->len;
+ np->stats.rx_packets++;
+
+ if (skb->ip_summed == CHECKSUM_HW) {
+ /* Defer checksum calculation. */
+ skb->proto_csum_blank = 1;
+ /* Must be a local packet: assert its integrity. */
+ skb->proto_data_valid = 1;
+ }
+
+ skb->ip_summed = skb->proto_data_valid ?
+ CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
+
+ skb->pkt_type = PACKET_HOST; /* overridden by eth_type_trans() */
+ skb->protocol = eth_type_trans(skb, dev);
+ skb->dev = dev;
+ dev->last_rx = jiffies;
+ netif_rx(skb);
+
+ return 0;
+}
+
+static struct net_device_stats *loopback_get_stats(struct net_device *dev)
+{
+ struct net_private *np = netdev_priv(dev);
+ return &np->stats;
+}
+
+static struct ethtool_ops network_ethtool_ops =
+{
+ .get_tx_csum = ethtool_op_get_tx_csum,
+ .set_tx_csum = ethtool_op_set_tx_csum,
+ .get_sg = ethtool_op_get_sg,
+ .set_sg = ethtool_op_set_sg,
+ .get_tso = ethtool_op_get_tso,
+ .set_tso = ethtool_op_set_tso,
+ .get_link = ethtool_op_get_link,
+};
+
+/*
+ * Nothing to do here. Virtual interface is point-to-point and the
+ * physical interface is probably promiscuous anyway.
+ */
+static void loopback_set_multicast_list(struct net_device *dev)
+{
+}
+
+static void loopback_construct(struct net_device *dev, struct net_device *lo)
+{
+ struct net_private *np = netdev_priv(dev);
+
+ np->loopback_dev = lo;
+
+ dev->open = loopback_open;
+ dev->stop = loopback_close;
+ dev->hard_start_xmit = loopback_start_xmit;
+ dev->get_stats = loopback_get_stats;
+ dev->set_multicast_list = loopback_set_multicast_list;
+ dev->change_mtu = NULL; /* allow arbitrary mtu */
+
+ dev->tx_queue_len = 0;
+
+ dev->features = (NETIF_F_HIGHDMA |
+ NETIF_F_LLTX |
+ NETIF_F_TSO |
+ NETIF_F_SG |
+ NETIF_F_IP_CSUM);
+
+ SET_ETHTOOL_OPS(dev, &network_ethtool_ops);
+
+ /*
+ * We do not set a jumbo MTU on the interface. Otherwise the network
+ * stack will try to send large packets that will get dropped by the
+ * Ethernet bridge (unless the physical Ethernet interface is
+ * configured to transfer jumbo packets). If a larger MTU is desired
+ * then the system administrator can specify it using the 'ifconfig'
+ * command.
+ */
+ /*dev->mtu = 16*1024;*/
+}
+
+static int __init make_loopback(int i)
+{
+ struct net_device *dev1, *dev2;
+ char dev_name[IFNAMSIZ];
+ int err = -ENOMEM;
+
+ sprintf(dev_name, "vif0.%d", i);
+ dev1 = alloc_netdev(sizeof(struct net_private), dev_name, ether_setup);
+ if (!dev1)
+ return err;
+
+ sprintf(dev_name, "veth%d", i);
+ dev2 = alloc_netdev(sizeof(struct net_private), dev_name, ether_setup);
+ if (!dev2)
+ goto fail_netdev2;
+
+ loopback_construct(dev1, dev2);
+ loopback_construct(dev2, dev1);
+
+ /*
+ * Initialise a dummy MAC address for the 'dummy backend' interface. We
+ * choose the numerically largest non-broadcast address to prevent the
+ * address getting stolen by an Ethernet bridge for STP purposes.
+ */
+ memset(dev1->dev_addr, 0xFF, ETH_ALEN);
+ dev1->dev_addr[0] &= ~0x01;
+
+ if ((err = register_netdev(dev1)) != 0)
+ goto fail;
+
+ if ((err = register_netdev(dev2)) != 0) {
+ unregister_netdev(dev1);
+ goto fail;
+ }
+
+ return 0;
+
+ fail:
+ free_netdev(dev2);
+ fail_netdev2:
+ free_netdev(dev1);
+ return err;
+}
+
+static void __init clean_loopback(int i)
+{
+ struct net_device *dev1, *dev2;
+ char dev_name[IFNAMSIZ];
+
+ sprintf(dev_name, "vif0.%d", i);
+ dev1 = dev_get_by_name(dev_name);
+ sprintf(dev_name, "veth%d", i);
+ dev2 = dev_get_by_name(dev_name);
+ if (dev1 && dev2) {
+ unregister_netdev(dev2);
+ unregister_netdev(dev1);
+ free_netdev(dev2);
+ free_netdev(dev1);
+ }
+}
+
+static int __init loopback_init(void)
+{
+ int i, err = 0;
+
+ for (i = 0; i < nloopbacks; i++)
+ if ((err = make_loopback(i)) != 0)
+ break;
+
+ return err;
+}
+
+module_init(loopback_init);
+
+static void __exit loopback_exit(void)
+{
+ int i;
+
+ for (i = nloopbacks; i-- > 0; )
+ clean_loopback(i);
+}
+
+module_exit(loopback_exit);
+
+MODULE_LICENSE("Dual BSD/GPL");
git://git.onelab.eu / linux-2.6.git / blobdiff