/*
 *      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/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)
{
        if (dev->ethtool_ops && dev->ethtool_ops->get_settings) {
                struct ethtool_cmd ecmd = { .cmd = ETHTOOL_GSET, };

                if (!dev_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
 */
u32 br_features_recompute(struct net_bridge *br, u32 features)
{
        struct net_bridge_port *p;
        u32 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)
                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 err0;

        err = br_fdb_insert(br, p, dev->dev_addr);
        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));

        kobject_uevent(&p->kobj, KOBJ_ADD);

        return 0;

err4:
        netdev_set_master(dev, NULL);
err3:
        sysfs_remove_link(br->ifobj, p->dev->name);
err2:
        br_fdb_delete_by_port(br, p, 1);
err1:
        kobject_put(&p->kobj);
        p = NULL; /* kobject_put frees */
err0:
        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();

}