/*
   *	Userspace interface
   *	Linux ethernet bridge
   *
   *	Authors:
   *	Lennert Buytenhek		<buytenh@gnu.org>
   *

   *	This program is free software; you can redistribute it and/or
   *	modify it under the terms of the GNU General Public License
   *	as published by the Free Software Foundation; either version
   *	2 of the License, or (at your option) any later version.
   */
  
  #include <linux/kernel.h>
  #include <linux/netdevice.h>

  #include <linux/etherdevice.h>

  #include <linux/netpoll.h>

  #include <linux/ethtool.h>
  #include <linux/if_arp.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/rtnetlink.h>

  #include <linux/if_ether.h>

  #include <linux/slab.h>

  #include <net/sock.h>
  
  #include "br_private.h"
  
  /*
   * Determine initial path cost based on speed.
   * using recommendations from 802.1d standard
   *

   * Since driver might sleep need to not be holding any locks.

   */

  static int port_cost(struct net_device *dev)

  {

  	struct ethtool_cmd ecmd;

  	if (!__ethtool_get_settings(dev, &ecmd)) {

  		switch (ethtool_cmd_speed(&ecmd)) {
  		case SPEED_10000:
  			return 2;
  		case SPEED_1000:
  			return 4;
  		case SPEED_100:
  			return 19;
  		case SPEED_10:
  			return 100;

  		}
  	}
  
  	/* Old silly heuristics based on name */
  	if (!strncmp(dev->name, "lec", 3))
  		return 7;
  
  	if (!strncmp(dev->name, "plip", 4))
  		return 2500;
  
  	return 100;	/* assume old 10Mbps */
  }

  /* Check for port carrier transistions. */

  void br_port_carrier_check(struct net_bridge_port *p)

  {

  	struct net_device *dev = p->dev;
  	struct net_bridge *br = p->br;

  	if (netif_running(dev) && netif_carrier_ok(dev))

  		p->path_cost = port_cost(dev);

  	if (!netif_running(br->dev))
  		return;
  
  	spin_lock_bh(&br->lock);
  	if (netif_running(dev) && netif_carrier_ok(dev)) {
  		if (p->state == BR_STATE_DISABLED)
  			br_stp_enable_port(p);
  	} else {
  		if (p->state != BR_STATE_DISABLED)
  			br_stp_disable_port(p);

  	}

  	spin_unlock_bh(&br->lock);

  }

  static void release_nbp(struct kobject *kobj)
  {
  	struct net_bridge_port *p
  		= container_of(kobj, struct net_bridge_port, kobj);
  	kfree(p);
  }
  
  static struct kobj_type brport_ktype = {
  #ifdef CONFIG_SYSFS
  	.sysfs_ops = &brport_sysfs_ops,
  #endif
  	.release = release_nbp,
  };

  static void destroy_nbp(struct net_bridge_port *p)
  {
  	struct net_device *dev = p->dev;

  	p->br = NULL;
  	p->dev = NULL;
  	dev_put(dev);

  	kobject_put(&p->kobj);

  }
  
  static void destroy_nbp_rcu(struct rcu_head *head)
  {
  	struct net_bridge_port *p =
  			container_of(head, struct net_bridge_port, rcu);
  	destroy_nbp(p);
  }

  /* Delete port(interface) from bridge is done in two steps.
   * via RCU. First step, marks device as down. That deletes
   * all the timers and stops new packets from flowing through.
   *
   * Final cleanup doesn't occur until after all CPU's finished
   * processing packets.
   *
   * Protected from multiple admin operations by RTNL mutex
   */

  static void del_nbp(struct net_bridge_port *p)
  {
  	struct net_bridge *br = p->br;
  	struct net_device *dev = p->dev;

  	sysfs_remove_link(br->ifobj, p->dev->name);

  	dev_set_promiscuity(dev, -1);
  
  	spin_lock_bh(&br->lock);
  	br_stp_disable_port(p);
  	spin_unlock_bh(&br->lock);

  	br_ifinfo_notify(RTM_DELLINK, p);

  	br_fdb_delete_by_port(br, p, 1);

  
  	list_del_rcu(&p->list);

  	dev->priv_flags &= ~IFF_BRIDGE_PORT;

  	netdev_rx_handler_unregister(dev);

  	synchronize_net();

  	netdev_set_master(dev, NULL);

  	br_multicast_del_port(p);

  	kobject_uevent(&p->kobj, KOBJ_REMOVE);

  	kobject_del(&p->kobj);

  	br_netpoll_disable(p);

  	call_rcu(&p->rcu, destroy_nbp_rcu);
  }

  /* Delete bridge device */
  void br_dev_delete(struct net_device *dev, struct list_head *head)

  {

  	struct net_bridge *br = netdev_priv(dev);

  	struct net_bridge_port *p, *n;
  
  	list_for_each_entry_safe(p, n, &br->port_list, list) {

  		del_nbp(p);
  	}
  
  	del_timer_sync(&br->gc_timer);
  
  	br_sysfs_delbr(br->dev);

  	unregister_netdevice_queue(br->dev, head);

  }

  /* find an available port number */
  static int find_portno(struct net_bridge *br)
  {
  	int index;
  	struct net_bridge_port *p;
  	unsigned long *inuse;

  	inuse = kcalloc(BITS_TO_LONGS(BR_MAX_PORTS), sizeof(unsigned long),

  			GFP_KERNEL);
  	if (!inuse)
  		return -ENOMEM;

  	set_bit(0, inuse);	/* zero is reserved */
  	list_for_each_entry(p, &br->port_list, list) {
  		set_bit(p->port_no, inuse);
  	}
  	index = find_first_zero_bit(inuse, BR_MAX_PORTS);
  	kfree(inuse);
  
  	return (index >= BR_MAX_PORTS) ? -EXFULL : index;
  }

  /* called with RTNL but without bridge lock */

  static struct net_bridge_port *new_nbp(struct net_bridge *br,

  				       struct net_device *dev)

  {
  	int index;
  	struct net_bridge_port *p;

  	index = find_portno(br);
  	if (index < 0)
  		return ERR_PTR(index);

  	p = kzalloc(sizeof(*p), GFP_KERNEL);

  	if (p == NULL)
  		return ERR_PTR(-ENOMEM);

  	p->br = br;
  	dev_hold(dev);
  	p->dev = dev;

  	p->path_cost = port_cost(dev);

  	p->priority = 0x8000 >> BR_PORT_BITS;

  	p->port_no = index;

  	p->flags = 0;

  	br_init_port(p);
  	p->state = BR_STATE_DISABLED;

  	br_stp_port_timer_init(p);

  	br_multicast_add_port(p);

  
  	return p;
  }

  int br_add_bridge(struct net *net, const char *name)

  {
  	struct net_device *dev;

  	int res;

  	dev = alloc_netdev(sizeof(struct net_bridge), name,
  			   br_dev_setup);

  	if (!dev)

  		return -ENOMEM;

  	dev_net_set(dev, net);

  	res = register_netdev(dev);
  	if (res)
  		free_netdev(dev);
  	return res;

  }

  int br_del_bridge(struct net *net, const char *name)

  {
  	struct net_device *dev;
  	int ret = 0;
  
  	rtnl_lock();

  	dev = __dev_get_by_name(net, name);

  	if (dev == NULL)

  		ret =  -ENXIO; 	/* Could not find device */
  
  	else if (!(dev->priv_flags & IFF_EBRIDGE)) {
  		/* Attempt to delete non bridge device! */
  		ret = -EPERM;
  	}
  
  	else if (dev->flags & IFF_UP) {
  		/* Not shutdown yet. */
  		ret = -EBUSY;

  	}

  	else

  		br_dev_delete(dev, NULL);

  
  	rtnl_unlock();
  	return ret;
  }

  /* MTU of the bridge pseudo-device: ETH_DATA_LEN or the minimum of the ports */

  int br_min_mtu(const struct net_bridge *br)
  {
  	const struct net_bridge_port *p;
  	int mtu = 0;
  
  	ASSERT_RTNL();
  
  	if (list_empty(&br->port_list))

  		mtu = ETH_DATA_LEN;

  	else {
  		list_for_each_entry(p, &br->port_list, list) {
  			if (!mtu  || p->dev->mtu < mtu)
  				mtu = p->dev->mtu;
  		}
  	}
  	return mtu;
  }

  /*
   * Recomputes features using slave's features
   */

  netdev_features_t br_features_recompute(struct net_bridge *br,
  	netdev_features_t features)

  {
  	struct net_bridge_port *p;

  	netdev_features_t mask;

  	if (list_empty(&br->port_list))

  		return features;

  	mask = features;

  	features &= ~NETIF_F_ONE_FOR_ALL;

  
  	list_for_each_entry(p, &br->port_list, list) {

  		features = netdev_increment_features(features,
  						     p->dev->features, mask);

  	}

  	return features;

  }

  /* called with RTNL */
  int br_add_if(struct net_bridge *br, struct net_device *dev)
  {
  	struct net_bridge_port *p;
  	int err = 0;

  	bool changed_addr;

  	/* Don't allow bridging non-ethernet like devices */
  	if ((dev->flags & IFF_LOOPBACK) ||

  	    dev->type != ARPHRD_ETHER || dev->addr_len != ETH_ALEN ||
  	    !is_valid_ether_addr(dev->dev_addr))

  		return -EINVAL;

  	/* No bridging of bridges */

  	if (dev->netdev_ops->ndo_start_xmit == br_dev_xmit)

  		return -ELOOP;

  	/* Device is already being bridged */

  	if (br_port_exists(dev))

  		return -EBUSY;

  	/* No bridging devices that dislike that (e.g. wireless) */
  	if (dev->priv_flags & IFF_DONT_BRIDGE)
  		return -EOPNOTSUPP;

  	p = new_nbp(br, dev);
  	if (IS_ERR(p))

  		return PTR_ERR(p);

  	call_netdevice_notifiers(NETDEV_JOIN, dev);

  	err = dev_set_promiscuity(dev, 1);
  	if (err)
  		goto put_back;

  	err = kobject_init_and_add(&p->kobj, &brport_ktype, &(dev->dev.kobj),
  				   SYSFS_BRIDGE_PORT_ATTR);

  	if (err)

  		goto err1;

  	err = br_sysfs_addif(p);
  	if (err)
  		goto err2;

  	if (br_netpoll_info(br) && ((err = br_netpoll_enable(p))))
  		goto err3;

  	err = netdev_set_master(dev, br->dev);

  	if (err)

  		goto err3;

  	err = netdev_rx_handler_register(dev, br_handle_frame, p);
  	if (err)
  		goto err4;

  	dev->priv_flags |= IFF_BRIDGE_PORT;

  	dev_disable_lro(dev);

  
  	list_add_rcu(&p->list, &br->port_list);

  	netdev_update_features(br->dev);

  	spin_lock_bh(&br->lock);

  	changed_addr = br_stp_recalculate_bridge_id(br);

  
  	if ((dev->flags & IFF_UP) && netif_carrier_ok(dev) &&
  	    (br->dev->flags & IFF_UP))
  		br_stp_enable_port(p);

  	spin_unlock_bh(&br->lock);

  	br_ifinfo_notify(RTM_NEWLINK, p);

  	if (changed_addr)

  		call_netdevice_notifiers(NETDEV_CHANGEADDR, br->dev);

  	dev_set_mtu(br->dev, br_min_mtu(br));

  	if (br_fdb_insert(br, p, dev->dev_addr))
  		netdev_err(dev, "failed insert local address bridge forwarding table
  ");

  	kobject_uevent(&p->kobj, KOBJ_ADD);

  	return 0;

  
  err4:
  	netdev_set_master(dev, NULL);

  err3:
  	sysfs_remove_link(br->ifobj, p->dev->name);

  err2:

  	kobject_put(&p->kobj);

  	p = NULL; /* kobject_put frees */

  err1:

  	dev_set_promiscuity(dev, -1);

  put_back:
  	dev_put(dev);

  	kfree(p);

  	return err;
  }
  
  /* called with RTNL */
  int br_del_if(struct net_bridge *br, struct net_device *dev)
  {

  	struct net_bridge_port *p;

  	bool changed_addr;

  	p = br_port_get_rtnl(dev);

  	if (!p || p->br != br)

  		return -EINVAL;

  	del_nbp(p);
  
  	spin_lock_bh(&br->lock);

  	changed_addr = br_stp_recalculate_bridge_id(br);

  	spin_unlock_bh(&br->lock);

  	if (changed_addr)
  		call_netdevice_notifiers(NETDEV_CHANGEADDR, br->dev);

  	netdev_update_features(br->dev);

  	return 0;
  }

  void __net_exit br_net_exit(struct net *net)

  {

  	struct net_device *dev;

  	LIST_HEAD(list);

  
  	rtnl_lock();

  	for_each_netdev(net, dev)
  		if (dev->priv_flags & IFF_EBRIDGE)

  			br_dev_delete(dev, &list);

  
  	unregister_netdevice_many(&list);

  	rtnl_unlock();
  
  }