/* Copyright (C) 2007-2013 B.A.T.M.A.N. contributors:
 *
 * Marek Lindner, Simon Wunderlich
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA
 */

#include "main.h"
#include "distributed-arp-table.h"
#include "hard-interface.h"
#include "soft-interface.h"
#include "send.h"
#include "translation-table.h"
#include "routing.h"
#include "sysfs.h"
#include "originator.h"
#include "hash.h"
#include "bridge_loop_avoidance.h"

#include <linux/if_arp.h>
#include <linux/if_ether.h>

void batadv_hardif_free_rcu(struct rcu_head *rcu)
{
        struct batadv_hard_iface *hard_iface;

        hard_iface = container_of(rcu, struct batadv_hard_iface, rcu);
        dev_put(hard_iface->net_dev);
        kfree(hard_iface);
}

struct batadv_hard_iface *
batadv_hardif_get_by_netdev(const struct net_device *net_dev)
{
        struct batadv_hard_iface *hard_iface;

        rcu_read_lock();
        list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
                if (hard_iface->net_dev == net_dev &&
                    atomic_inc_not_zero(&hard_iface->refcount))
                        goto out;
        }

        hard_iface = NULL;

out:
        rcu_read_unlock();
        return hard_iface;
}

/**
 * batadv_is_on_batman_iface - check if a device is a batman iface descendant
 * @net_dev: the device to check
 *
 * If the user creates any virtual device on top of a batman-adv interface, it
 * is important to prevent this new interface to be used to create a new mesh
 * network (this behaviour would lead to a batman-over-batman configuration).
 * This function recursively checks all the fathers of the device passed as
 * argument looking for a batman-adv soft interface.
 *
 * Returns true if the device is descendant of a batman-adv mesh interface (or
 * if it is a batman-adv interface itself), false otherwise
 */
static bool batadv_is_on_batman_iface(const struct net_device *net_dev)
{
        struct net_device *parent_dev;
        bool ret;

        /* check if this is a batman-adv mesh interface */
        if (batadv_softif_is_valid(net_dev))
                return true;

        /* no more parents..stop recursion */
        if (net_dev->iflink == net_dev->ifindex)
                return false;

        /* recurse over the parent device */
        parent_dev = dev_get_by_index(&init_net, net_dev->iflink);
        /* if we got a NULL parent_dev there is something broken.. */
        if (WARN(!parent_dev, "Cannot find parent device"))
                return false;

        ret = batadv_is_on_batman_iface(parent_dev);

        if (parent_dev)
                dev_put(parent_dev);
        return ret;
}

static int batadv_is_valid_iface(const struct net_device *net_dev)
{
        if (net_dev->flags & IFF_LOOPBACK)
                return 0;

        if (net_dev->type != ARPHRD_ETHER)
                return 0;

        if (net_dev->addr_len != ETH_ALEN)
                return 0;

        /* no batman over batman */
        if (batadv_is_on_batman_iface(net_dev))
                return 0;

        return 1;
}

/**
 * batadv_is_wifi_netdev - check if the given net_device struct is a wifi
 *  interface
 * @net_device: the device to check
 *
 * Returns true if the net device is a 802.11 wireless device, false otherwise.
 */
static bool batadv_is_wifi_netdev(struct net_device *net_device)
{
#ifdef CONFIG_WIRELESS_EXT
        /* pre-cfg80211 drivers have to implement WEXT, so it is possible to
         * check for wireless_handlers != NULL
         */
        if (net_device->wireless_handlers)
                return true;
#endif

        /* cfg80211 drivers have to set ieee80211_ptr */
        if (net_device->ieee80211_ptr)
                return true;

        return false;
}

/**
 * batadv_is_wifi_iface - check if the given interface represented by ifindex
 *  is a wifi interface
 * @ifindex: interface index to check
 *
 * Returns true if the interface represented by ifindex is a 802.11 wireless
 * device, false otherwise.
 */
bool batadv_is_wifi_iface(int ifindex)
{
        struct net_device *net_device = NULL;
        bool ret = false;

        if (ifindex == BATADV_NULL_IFINDEX)
                goto out;

        net_device = dev_get_by_index(&init_net, ifindex);
        if (!net_device)
                goto out;

        ret = batadv_is_wifi_netdev(net_device);

out:
        if (net_device)
                dev_put(net_device);
        return ret;
}

static struct batadv_hard_iface *
batadv_hardif_get_active(const struct net_device *soft_iface)
{
        struct batadv_hard_iface *hard_iface;

        rcu_read_lock();
        list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
                if (hard_iface->soft_iface != soft_iface)
                        continue;

                if (hard_iface->if_status == BATADV_IF_ACTIVE &&
                    atomic_inc_not_zero(&hard_iface->refcount))
                        goto out;
        }

        hard_iface = NULL;

out:
        rcu_read_unlock();
        return hard_iface;
}

static void batadv_primary_if_update_addr(struct batadv_priv *bat_priv,
                                          struct batadv_hard_iface *oldif)
{
        struct batadv_vis_packet *vis_packet;
        struct batadv_hard_iface *primary_if;
        struct sk_buff *skb;

        primary_if = batadv_primary_if_get_selected(bat_priv);
        if (!primary_if)
                goto out;

        batadv_dat_init_own_addr(bat_priv, primary_if);

        skb = bat_priv->vis.my_info->skb_packet;
        vis_packet = (struct batadv_vis_packet *)skb->data;
        memcpy(vis_packet->vis_orig, primary_if->net_dev->dev_addr, ETH_ALEN);
        memcpy(vis_packet->sender_orig,
               primary_if->net_dev->dev_addr, ETH_ALEN);

        batadv_bla_update_orig_address(bat_priv, primary_if, oldif);
out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
}

static void batadv_primary_if_select(struct batadv_priv *bat_priv,
                                     struct batadv_hard_iface *new_hard_iface)
{
        struct batadv_hard_iface *curr_hard_iface;

        ASSERT_RTNL();

        if (new_hard_iface && !atomic_inc_not_zero(&new_hard_iface->refcount))
                new_hard_iface = NULL;

        curr_hard_iface = rcu_dereference_protected(bat_priv->primary_if, 1);
        rcu_assign_pointer(bat_priv->primary_if, new_hard_iface);

        if (!new_hard_iface)
                goto out;

        bat_priv->bat_algo_ops->bat_primary_iface_set(new_hard_iface);
        batadv_primary_if_update_addr(bat_priv, curr_hard_iface);

out:
        if (curr_hard_iface)
                batadv_hardif_free_ref(curr_hard_iface);
}

static bool
batadv_hardif_is_iface_up(const struct batadv_hard_iface *hard_iface)
{
        if (hard_iface->net_dev->flags & IFF_UP)
                return true;

        return false;
}

static void batadv_check_known_mac_addr(const struct net_device *net_dev)
{
        const struct batadv_hard_iface *hard_iface;

        rcu_read_lock();
        list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
                if ((hard_iface->if_status != BATADV_IF_ACTIVE) &&
                    (hard_iface->if_status != BATADV_IF_TO_BE_ACTIVATED))
                        continue;

                if (hard_iface->net_dev == net_dev)
                        continue;

                if (!batadv_compare_eth(hard_iface->net_dev->dev_addr,
                                        net_dev->dev_addr))
                        continue;

                pr_warn("The newly added mac address (%pM) already exists on: %s\n",
                        net_dev->dev_addr, hard_iface->net_dev->name);
                pr_warn("It is strongly recommended to keep mac addresses unique to avoid problems!\n");
        }
        rcu_read_unlock();
}

int batadv_hardif_min_mtu(struct net_device *soft_iface)
{
        const struct batadv_priv *bat_priv = netdev_priv(soft_iface);
        const struct batadv_hard_iface *hard_iface;
        /* allow big frames if all devices are capable to do so
         * (have MTU > 1500 + BAT_HEADER_LEN)
         */
        int min_mtu = ETH_DATA_LEN;

        if (atomic_read(&bat_priv->fragmentation))
                goto out;

        rcu_read_lock();
        list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
                if ((hard_iface->if_status != BATADV_IF_ACTIVE) &&
                    (hard_iface->if_status != BATADV_IF_TO_BE_ACTIVATED))
                        continue;

                if (hard_iface->soft_iface != soft_iface)
                        continue;

                min_mtu = min_t(int,
                                hard_iface->net_dev->mtu - BATADV_HEADER_LEN,
                                min_mtu);
        }
        rcu_read_unlock();
out:
        return min_mtu;
}

/* adjusts the MTU if a new interface with a smaller MTU appeared. */
void batadv_update_min_mtu(struct net_device *soft_iface)
{
        int min_mtu;

        min_mtu = batadv_hardif_min_mtu(soft_iface);
        if (soft_iface->mtu != min_mtu)
                soft_iface->mtu = min_mtu;
}

static void
batadv_hardif_activate_interface(struct batadv_hard_iface *hard_iface)
{
        struct batadv_priv *bat_priv;
        struct batadv_hard_iface *primary_if = NULL;

        if (hard_iface->if_status != BATADV_IF_INACTIVE)
                goto out;

        bat_priv = netdev_priv(hard_iface->soft_iface);

        bat_priv->bat_algo_ops->bat_iface_update_mac(hard_iface);
        hard_iface->if_status = BATADV_IF_TO_BE_ACTIVATED;

        /* the first active interface becomes our primary interface or
         * the next active interface after the old primary interface was removed
         */
        primary_if = batadv_primary_if_get_selected(bat_priv);
        if (!primary_if)
                batadv_primary_if_select(bat_priv, hard_iface);

        batadv_info(hard_iface->soft_iface, "Interface activated: %s\n",
                    hard_iface->net_dev->name);

        batadv_update_min_mtu(hard_iface->soft_iface);

out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
}

static void
batadv_hardif_deactivate_interface(struct batadv_hard_iface *hard_iface)
{
        if ((hard_iface->if_status != BATADV_IF_ACTIVE) &&
            (hard_iface->if_status != BATADV_IF_TO_BE_ACTIVATED))
                return;

        hard_iface->if_status = BATADV_IF_INACTIVE;

        batadv_info(hard_iface->soft_iface, "Interface deactivated: %s\n",
                    hard_iface->net_dev->name);

        batadv_update_min_mtu(hard_iface->soft_iface);
}

/**
 * batadv_master_del_slave - remove hard_iface from the current master interface
 * @slave: the interface enslaved in another master
 * @master: the master from which slave has to be removed
 *
 * Invoke ndo_del_slave on master passing slave as argument. In this way slave
 * is free'd and master can correctly change its internal state.
 * Return 0 on success, a negative value representing the error otherwise
 */
static int batadv_master_del_slave(struct batadv_hard_iface *slave,
                                   struct net_device *master)
{
        int ret;

        if (!master)
                return 0;

        ret = -EBUSY;
        if (master->netdev_ops->ndo_del_slave)
                ret = master->netdev_ops->ndo_del_slave(master, slave->net_dev);

        return ret;
}

int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
                                   const char *iface_name)
{
        struct batadv_priv *bat_priv;
        struct net_device *soft_iface, *master;
        __be16 ethertype = __constant_htons(ETH_P_BATMAN);
        int ret;

        if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
                goto out;

        if (!atomic_inc_not_zero(&hard_iface->refcount))
                goto out;

        soft_iface = dev_get_by_name(&init_net, iface_name);

        if (!soft_iface) {
                soft_iface = batadv_softif_create(iface_name);

                if (!soft_iface) {
                        ret = -ENOMEM;
                        goto err;
                }

                /* dev_get_by_name() increases the reference counter for us */
                dev_hold(soft_iface);
        }

        if (!batadv_softif_is_valid(soft_iface)) {
                pr_err("Can't create batman mesh interface %s: already exists as regular interface\n",
                       soft_iface->name);
                ret = -EINVAL;
                goto err_dev;
        }

        /* check if the interface is enslaved in another virtual one and
         * in that case unlink it first
         */
        master = netdev_master_upper_dev_get(hard_iface->net_dev);
        ret = batadv_master_del_slave(hard_iface, master);
        if (ret)
                goto err_dev;

        hard_iface->soft_iface = soft_iface;
        bat_priv = netdev_priv(hard_iface->soft_iface);

        ret = netdev_master_upper_dev_link(hard_iface->net_dev, soft_iface);
        if (ret)
                goto err_dev;

        ret = bat_priv->bat_algo_ops->bat_iface_enable(hard_iface);
        if (ret < 0)
                goto err_upper;

        hard_iface->if_num = bat_priv->num_ifaces;
        bat_priv->num_ifaces++;
        hard_iface->if_status = BATADV_IF_INACTIVE;
        ret = batadv_orig_hash_add_if(hard_iface, bat_priv->num_ifaces);
        if (ret < 0) {
                bat_priv->bat_algo_ops->bat_iface_disable(hard_iface);
                bat_priv->num_ifaces--;
                hard_iface->if_status = BATADV_IF_NOT_IN_USE;
                goto err_upper;
        }

        hard_iface->batman_adv_ptype.type = ethertype;
        hard_iface->batman_adv_ptype.func = batadv_batman_skb_recv;
        hard_iface->batman_adv_ptype.dev = hard_iface->net_dev;
        dev_add_pack(&hard_iface->batman_adv_ptype);

        atomic_set(&hard_iface->frag_seqno, 1);
        batadv_info(hard_iface->soft_iface, "Adding interface: %s\n",
                    hard_iface->net_dev->name);

        if (atomic_read(&bat_priv->fragmentation) &&
            hard_iface->net_dev->mtu < ETH_DATA_LEN + BATADV_HEADER_LEN)
                batadv_info(hard_iface->soft_iface,
                            "The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to %zi would solve the problem.\n",
                            hard_iface->net_dev->name, hard_iface->net_dev->mtu,
                            ETH_DATA_LEN + BATADV_HEADER_LEN);

        if (!atomic_read(&bat_priv->fragmentation) &&
            hard_iface->net_dev->mtu < ETH_DATA_LEN + BATADV_HEADER_LEN)
                batadv_info(hard_iface->soft_iface,
                            "The MTU of interface %s is too small (%i) to handle the transport of batman-adv packets. If you experience problems getting traffic through try increasing the MTU to %zi.\n",
                            hard_iface->net_dev->name, hard_iface->net_dev->mtu,
                            ETH_DATA_LEN + BATADV_HEADER_LEN);

        if (batadv_hardif_is_iface_up(hard_iface))
                batadv_hardif_activate_interface(hard_iface);
        else
                batadv_err(hard_iface->soft_iface,
                           "Not using interface %s (retrying later): interface not active\n",
                           hard_iface->net_dev->name);

        /* begin scheduling originator messages on that interface */
        batadv_schedule_bat_ogm(hard_iface);

out:
        return 0;

err_upper:
        netdev_upper_dev_unlink(hard_iface->net_dev, soft_iface);
err_dev:
        hard_iface->soft_iface = NULL;
        dev_put(soft_iface);
err:
        batadv_hardif_free_ref(hard_iface);
        return ret;
}

void batadv_hardif_disable_interface(struct batadv_hard_iface *hard_iface,
                                     enum batadv_hard_if_cleanup autodel)
{
        struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
        struct batadv_hard_iface *primary_if = NULL;

        if (hard_iface->if_status == BATADV_IF_ACTIVE)
                batadv_hardif_deactivate_interface(hard_iface);

        if (hard_iface->if_status != BATADV_IF_INACTIVE)
                goto out;

        batadv_info(hard_iface->soft_iface, "Removing interface: %s\n",
                    hard_iface->net_dev->name);
        dev_remove_pack(&hard_iface->batman_adv_ptype);

        bat_priv->num_ifaces--;
        batadv_orig_hash_del_if(hard_iface, bat_priv->num_ifaces);

        primary_if = batadv_primary_if_get_selected(bat_priv);
        if (hard_iface == primary_if) {
                struct batadv_hard_iface *new_if;

                new_if = batadv_hardif_get_active(hard_iface->soft_iface);
                batadv_primary_if_select(bat_priv, new_if);

                if (new_if)
                        batadv_hardif_free_ref(new_if);
        }

        bat_priv->bat_algo_ops->bat_iface_disable(hard_iface);
        hard_iface->if_status = BATADV_IF_NOT_IN_USE;

        /* delete all references to this hard_iface */
        batadv_purge_orig_ref(bat_priv);
        batadv_purge_outstanding_packets(bat_priv, hard_iface);
        dev_put(hard_iface->soft_iface);

        /* nobody uses this interface anymore */
        if (!bat_priv->num_ifaces && autodel == BATADV_IF_CLEANUP_AUTO)
                batadv_softif_destroy_sysfs(hard_iface->soft_iface);

        netdev_upper_dev_unlink(hard_iface->net_dev, hard_iface->soft_iface);
        hard_iface->soft_iface = NULL;
        batadv_hardif_free_ref(hard_iface);

out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
}

/**
 * batadv_hardif_remove_interface_finish - cleans up the remains of a hardif
 * @work: work queue item
 *
 * Free the parts of the hard interface which can not be removed under
 * rtnl lock (to prevent deadlock situations).
 */
static void batadv_hardif_remove_interface_finish(struct work_struct *work)
{
        struct batadv_hard_iface *hard_iface;

        hard_iface = container_of(work, struct batadv_hard_iface,
                                  cleanup_work);

        batadv_sysfs_del_hardif(&hard_iface->hardif_obj);
        batadv_hardif_free_ref(hard_iface);
}

static struct batadv_hard_iface *
batadv_hardif_add_interface(struct net_device *net_dev)
{
        struct batadv_hard_iface *hard_iface;
        int ret;

        ASSERT_RTNL();

        ret = batadv_is_valid_iface(net_dev);
        if (ret != 1)
                goto out;

        dev_hold(net_dev);

        hard_iface = kzalloc(sizeof(*hard_iface), GFP_ATOMIC);
        if (!hard_iface)
                goto release_dev;

        ret = batadv_sysfs_add_hardif(&hard_iface->hardif_obj, net_dev);
        if (ret)
                goto free_if;

        hard_iface->if_num = -1;
        hard_iface->net_dev = net_dev;
        hard_iface->soft_iface = NULL;
        hard_iface->if_status = BATADV_IF_NOT_IN_USE;
        INIT_LIST_HEAD(&hard_iface->list);
        INIT_WORK(&hard_iface->cleanup_work,
                  batadv_hardif_remove_interface_finish);

        hard_iface->num_bcasts = BATADV_NUM_BCASTS_DEFAULT;
        if (batadv_is_wifi_netdev(net_dev))
                hard_iface->num_bcasts = BATADV_NUM_BCASTS_WIRELESS;

        /* extra reference for return */
        atomic_set(&hard_iface->refcount, 2);

        batadv_check_known_mac_addr(hard_iface->net_dev);
        list_add_tail_rcu(&hard_iface->list, &batadv_hardif_list);

        return hard_iface;

free_if:
        kfree(hard_iface);
release_dev:
        dev_put(net_dev);
out:
        return NULL;
}

static void batadv_hardif_remove_interface(struct batadv_hard_iface *hard_iface)
{
        ASSERT_RTNL();

        /* first deactivate interface */
        if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
                batadv_hardif_disable_interface(hard_iface,
                                                BATADV_IF_CLEANUP_AUTO);

        if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
                return;

        hard_iface->if_status = BATADV_IF_TO_BE_REMOVED;
        queue_work(batadv_event_workqueue, &hard_iface->cleanup_work);
}

void batadv_hardif_remove_interfaces(void)
{
        struct batadv_hard_iface *hard_iface, *hard_iface_tmp;

        rtnl_lock();
        list_for_each_entry_safe(hard_iface, hard_iface_tmp,
                                 &batadv_hardif_list, list) {
                list_del_rcu(&hard_iface->list);
                batadv_hardif_remove_interface(hard_iface);
        }
        rtnl_unlock();
}

static int batadv_hard_if_event(struct notifier_block *this,
                                unsigned long event, void *ptr)
{
        struct net_device *net_dev = netdev_notifier_info_to_dev(ptr);
        struct batadv_hard_iface *hard_iface;
        struct batadv_hard_iface *primary_if = NULL;
        struct batadv_priv *bat_priv;

        if (batadv_softif_is_valid(net_dev) && event == NETDEV_REGISTER) {
                batadv_sysfs_add_meshif(net_dev);
                return NOTIFY_DONE;
        }

        hard_iface = batadv_hardif_get_by_netdev(net_dev);
        if (!hard_iface && event == NETDEV_REGISTER)
                hard_iface = batadv_hardif_add_interface(net_dev);

        if (!hard_iface)
                goto out;

        switch (event) {
        case NETDEV_UP:
                batadv_hardif_activate_interface(hard_iface);
                break;
        case NETDEV_GOING_DOWN:
        case NETDEV_DOWN:
                batadv_hardif_deactivate_interface(hard_iface);
                break;
        case NETDEV_UNREGISTER:
                list_del_rcu(&hard_iface->list);

                batadv_hardif_remove_interface(hard_iface);
                break;
        case NETDEV_CHANGEMTU:
                if (hard_iface->soft_iface)
                        batadv_update_min_mtu(hard_iface->soft_iface);
                break;
        case NETDEV_CHANGEADDR:
                if (hard_iface->if_status == BATADV_IF_NOT_IN_USE)
                        goto hardif_put;

                batadv_check_known_mac_addr(hard_iface->net_dev);

                bat_priv = netdev_priv(hard_iface->soft_iface);
                bat_priv->bat_algo_ops->bat_iface_update_mac(hard_iface);

                primary_if = batadv_primary_if_get_selected(bat_priv);
                if (!primary_if)
                        goto hardif_put;

                if (hard_iface == primary_if)
                        batadv_primary_if_update_addr(bat_priv, NULL);
                break;
        default:
                break;
        }

hardif_put:
        batadv_hardif_free_ref(hard_iface);
out:
        if (primary_if)
                batadv_hardif_free_ref(primary_if);
        return NOTIFY_DONE;
}

struct notifier_block batadv_hard_if_notifier = {
        .notifier_call = batadv_hard_if_event,
};