/*
   *  drivers/net/veth.c
   *
   *  Copyright (C) 2007 OpenVZ http://openvz.org, SWsoft Inc
   *
   * Author: Pavel Emelianov <xemul@openvz.org>
   * Ethtool interface from: Eric W. Biederman <ebiederm@xmission.com>
   *
   */

  #include <linux/netdevice.h>

  #include <linux/slab.h>

  #include <linux/ethtool.h>
  #include <linux/etherdevice.h>

  #include <linux/u64_stats_sync.h>

  
  #include <net/dst.h>
  #include <net/xfrm.h>

  #include <linux/veth.h>

  #include <linux/module.h>

  
  #define DRV_NAME	"veth"
  #define DRV_VERSION	"1.0"

  #define MIN_MTU 68		/* Min L3 MTU */
  #define MAX_MTU 65535		/* Max L3 MTU (arbitrary) */

  struct veth_net_stats {

  	u64			rx_packets;

  	u64			rx_bytes;

  	u64			tx_packets;

  	u64			tx_bytes;
  	u64			rx_dropped;

  	struct u64_stats_sync	syncp;

  };
  
  struct veth_priv {
  	struct net_device *peer;

  	struct veth_net_stats __percpu *stats;

  };

  /*
   * ethtool interface
   */
  
  static struct {
  	const char string[ETH_GSTRING_LEN];
  } ethtool_stats_keys[] = {
  	{ "peer_ifindex" },
  };
  
  static int veth_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
  {
  	cmd->supported		= 0;
  	cmd->advertising	= 0;

  	ethtool_cmd_speed_set(cmd, SPEED_10000);

  	cmd->duplex		= DUPLEX_FULL;
  	cmd->port		= PORT_TP;
  	cmd->phy_address	= 0;
  	cmd->transceiver	= XCVR_INTERNAL;
  	cmd->autoneg		= AUTONEG_DISABLE;
  	cmd->maxtxpkt		= 0;
  	cmd->maxrxpkt		= 0;
  	return 0;
  }
  
  static void veth_get_drvinfo(struct net_device *dev, struct ethtool_drvinfo *info)
  {

  	strlcpy(info->driver, DRV_NAME, sizeof(info->driver));
  	strlcpy(info->version, DRV_VERSION, sizeof(info->version));

  }
  
  static void veth_get_strings(struct net_device *dev, u32 stringset, u8 *buf)
  {
  	switch(stringset) {
  	case ETH_SS_STATS:
  		memcpy(buf, &ethtool_stats_keys, sizeof(ethtool_stats_keys));
  		break;
  	}
  }

  static int veth_get_sset_count(struct net_device *dev, int sset)

  {

  	switch (sset) {
  	case ETH_SS_STATS:
  		return ARRAY_SIZE(ethtool_stats_keys);
  	default:
  		return -EOPNOTSUPP;
  	}

  }
  
  static void veth_get_ethtool_stats(struct net_device *dev,
  		struct ethtool_stats *stats, u64 *data)
  {
  	struct veth_priv *priv;
  
  	priv = netdev_priv(dev);
  	data[0] = priv->peer->ifindex;
  }

  static const struct ethtool_ops veth_ethtool_ops = {

  	.get_settings		= veth_get_settings,
  	.get_drvinfo		= veth_get_drvinfo,
  	.get_link		= ethtool_op_get_link,

  	.get_strings		= veth_get_strings,

  	.get_sset_count		= veth_get_sset_count,

  	.get_ethtool_stats	= veth_get_ethtool_stats,
  };
  
  /*
   * xmit
   */

  static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)

  {
  	struct net_device *rcv = NULL;
  	struct veth_priv *priv, *rcv_priv;

  	struct veth_net_stats *stats, *rcv_stats;

  	int length;

  	priv = netdev_priv(dev);
  	rcv = priv->peer;
  	rcv_priv = netdev_priv(rcv);

  	stats = this_cpu_ptr(priv->stats);
  	rcv_stats = this_cpu_ptr(rcv_priv->stats);

  	/* don't change ip_summed == CHECKSUM_PARTIAL, as that
  	   will cause bad checksum on forwarded packets */

  	if (skb->ip_summed == CHECKSUM_NONE &&
  	    rcv->features & NETIF_F_RXCSUM)
  		skb->ip_summed = CHECKSUM_UNNECESSARY;

  	length = skb->len;

  	if (dev_forward_skb(rcv, skb) != NET_RX_SUCCESS)
  		goto rx_drop;

  	u64_stats_update_begin(&stats->syncp);

  	stats->tx_bytes += length;
  	stats->tx_packets++;

  	u64_stats_update_end(&stats->syncp);

  	u64_stats_update_begin(&rcv_stats->syncp);

  	rcv_stats->rx_bytes += length;
  	rcv_stats->rx_packets++;

  	u64_stats_update_end(&rcv_stats->syncp);

  	return NETDEV_TX_OK;

  rx_drop:

  	u64_stats_update_begin(&rcv_stats->syncp);

  	rcv_stats->rx_dropped++;

  	u64_stats_update_end(&rcv_stats->syncp);

  	return NETDEV_TX_OK;

  }
  
  /*
   * general routines
   */

  static struct rtnl_link_stats64 *veth_get_stats64(struct net_device *dev,
  						  struct rtnl_link_stats64 *tot)

  {

  	struct veth_priv *priv = netdev_priv(dev);

  	int cpu;

  	for_each_possible_cpu(cpu) {

  		struct veth_net_stats *stats = per_cpu_ptr(priv->stats, cpu);
  		u64 rx_packets, rx_bytes, rx_dropped;

  		u64 tx_packets, tx_bytes;

  		unsigned int start;
  
  		do {
  			start = u64_stats_fetch_begin_bh(&stats->syncp);
  			rx_packets = stats->rx_packets;
  			tx_packets = stats->tx_packets;
  			rx_bytes = stats->rx_bytes;
  			tx_bytes = stats->tx_bytes;
  			rx_dropped = stats->rx_dropped;

  		} while (u64_stats_fetch_retry_bh(&stats->syncp, start));
  		tot->rx_packets += rx_packets;
  		tot->tx_packets += tx_packets;
  		tot->rx_bytes   += rx_bytes;
  		tot->tx_bytes   += tx_bytes;
  		tot->rx_dropped += rx_dropped;

  	}

  
  	return tot;

  }
  
  static int veth_open(struct net_device *dev)
  {
  	struct veth_priv *priv;
  
  	priv = netdev_priv(dev);
  	if (priv->peer == NULL)
  		return -ENOTCONN;
  
  	if (priv->peer->flags & IFF_UP) {
  		netif_carrier_on(dev);
  		netif_carrier_on(priv->peer);
  	}
  	return 0;
  }

  static int veth_close(struct net_device *dev)
  {
  	struct veth_priv *priv = netdev_priv(dev);
  
  	netif_carrier_off(dev);
  	netif_carrier_off(priv->peer);
  
  	return 0;
  }

  static int is_valid_veth_mtu(int new_mtu)
  {

  	return new_mtu >= MIN_MTU && new_mtu <= MAX_MTU;

  }
  
  static int veth_change_mtu(struct net_device *dev, int new_mtu)
  {
  	if (!is_valid_veth_mtu(new_mtu))
  		return -EINVAL;
  	dev->mtu = new_mtu;
  	return 0;
  }

  static int veth_dev_init(struct net_device *dev)
  {

  	struct veth_net_stats __percpu *stats;

  	struct veth_priv *priv;
  
  	stats = alloc_percpu(struct veth_net_stats);
  	if (stats == NULL)
  		return -ENOMEM;
  
  	priv = netdev_priv(dev);
  	priv->stats = stats;
  	return 0;
  }

  static void veth_dev_free(struct net_device *dev)
  {
  	struct veth_priv *priv;
  
  	priv = netdev_priv(dev);
  	free_percpu(priv->stats);
  	free_netdev(dev);
  }

  static const struct net_device_ops veth_netdev_ops = {

  	.ndo_init            = veth_dev_init,
  	.ndo_open            = veth_open,

  	.ndo_stop            = veth_close,

  	.ndo_start_xmit      = veth_xmit,

  	.ndo_change_mtu      = veth_change_mtu,

  	.ndo_get_stats64     = veth_get_stats64,

  	.ndo_set_mac_address = eth_mac_addr,

  };

  static void veth_setup(struct net_device *dev)
  {
  	ether_setup(dev);

  	dev->priv_flags &= ~IFF_TX_SKB_SHARING;

  	dev->netdev_ops = &veth_netdev_ops;

  	dev->ethtool_ops = &veth_ethtool_ops;
  	dev->features |= NETIF_F_LLTX;

  	dev->destructor = veth_dev_free;

  	dev->hw_features = NETIF_F_HW_CSUM | NETIF_F_SG | NETIF_F_RXCSUM;

  }
  
  /*
   * netlink interface
   */
  
  static int veth_validate(struct nlattr *tb[], struct nlattr *data[])
  {
  	if (tb[IFLA_ADDRESS]) {
  		if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN)
  			return -EINVAL;
  		if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS])))
  			return -EADDRNOTAVAIL;
  	}

  	if (tb[IFLA_MTU]) {
  		if (!is_valid_veth_mtu(nla_get_u32(tb[IFLA_MTU])))
  			return -EINVAL;
  	}

  	return 0;
  }
  
  static struct rtnl_link_ops veth_link_ops;

  static int veth_newlink(struct net *src_net, struct net_device *dev,

  			 struct nlattr *tb[], struct nlattr *data[])
  {
  	int err;
  	struct net_device *peer;
  	struct veth_priv *priv;
  	char ifname[IFNAMSIZ];
  	struct nlattr *peer_tb[IFLA_MAX + 1], **tbp;

  	struct ifinfomsg *ifmp;

  	struct net *net;

  
  	/*
  	 * create and register peer first

  	 */

  	if (data != NULL && data[VETH_INFO_PEER] != NULL) {
  		struct nlattr *nla_peer;
  
  		nla_peer = data[VETH_INFO_PEER];

  		ifmp = nla_data(nla_peer);

  		err = nla_parse(peer_tb, IFLA_MAX,
  				nla_data(nla_peer) + sizeof(struct ifinfomsg),
  				nla_len(nla_peer) - sizeof(struct ifinfomsg),
  				ifla_policy);
  		if (err < 0)
  			return err;
  
  		err = veth_validate(peer_tb, NULL);
  		if (err < 0)
  			return err;
  
  		tbp = peer_tb;

  	} else {
  		ifmp = NULL;

  		tbp = tb;

  	}

  
  	if (tbp[IFLA_IFNAME])
  		nla_strlcpy(ifname, tbp[IFLA_IFNAME], IFNAMSIZ);
  	else
  		snprintf(ifname, IFNAMSIZ, DRV_NAME "%%d");

  	net = rtnl_link_get_net(src_net, tbp);
  	if (IS_ERR(net))
  		return PTR_ERR(net);
  
  	peer = rtnl_create_link(src_net, net, ifname, &veth_link_ops, tbp);
  	if (IS_ERR(peer)) {
  		put_net(net);

  		return PTR_ERR(peer);

  	}

  
  	if (tbp[IFLA_ADDRESS] == NULL)
  		random_ether_addr(peer->dev_addr);
  
  	err = register_netdevice(peer);

  	put_net(net);
  	net = NULL;

  	if (err < 0)
  		goto err_register_peer;
  
  	netif_carrier_off(peer);

  	err = rtnl_configure_link(peer, ifmp);
  	if (err < 0)
  		goto err_configure_peer;

  	/*
  	 * register dev last
  	 *
  	 * note, that since we've registered new device the dev's name
  	 * should be re-allocated
  	 */
  
  	if (tb[IFLA_ADDRESS] == NULL)
  		random_ether_addr(dev->dev_addr);

  	if (tb[IFLA_IFNAME])
  		nla_strlcpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
  	else
  		snprintf(dev->name, IFNAMSIZ, DRV_NAME "%%d");
  
  	if (strchr(dev->name, '%')) {
  		err = dev_alloc_name(dev, dev->name);
  		if (err < 0)
  			goto err_alloc_name;
  	}

  	err = register_netdevice(dev);
  	if (err < 0)
  		goto err_register_dev;
  
  	netif_carrier_off(dev);
  
  	/*
  	 * tie the deviced together
  	 */
  
  	priv = netdev_priv(dev);

  	priv->peer = peer;

  
  	priv = netdev_priv(peer);

  	priv->peer = dev;

  	return 0;
  
  err_register_dev:
  	/* nothing to do */

  err_alloc_name:

  err_configure_peer:

  	unregister_netdevice(peer);
  	return err;
  
  err_register_peer:
  	free_netdev(peer);
  	return err;
  }

  static void veth_dellink(struct net_device *dev, struct list_head *head)

  {
  	struct veth_priv *priv;
  	struct net_device *peer;
  
  	priv = netdev_priv(dev);
  	peer = priv->peer;

  	unregister_netdevice_queue(dev, head);
  	unregister_netdevice_queue(peer, head);

  }
  
  static const struct nla_policy veth_policy[VETH_INFO_MAX + 1];
  
  static struct rtnl_link_ops veth_link_ops = {
  	.kind		= DRV_NAME,
  	.priv_size	= sizeof(struct veth_priv),
  	.setup		= veth_setup,
  	.validate	= veth_validate,
  	.newlink	= veth_newlink,
  	.dellink	= veth_dellink,
  	.policy		= veth_policy,
  	.maxtype	= VETH_INFO_MAX,
  };
  
  /*
   * init/fini
   */
  
  static __init int veth_init(void)
  {
  	return rtnl_link_register(&veth_link_ops);
  }
  
  static __exit void veth_exit(void)
  {

  	rtnl_link_unregister(&veth_link_ops);

  }
  
  module_init(veth_init);
  module_exit(veth_exit);
  
  MODULE_DESCRIPTION("Virtual Ethernet Tunnel");
  MODULE_LICENSE("GPL v2");
  MODULE_ALIAS_RTNL_LINK(DRV_NAME);