// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2013-2020  B.A.T.M.A.N. contributors:
 *
 * Linus Lüssing, Marek Lindner
 */

#include "bat_v.h"
#include "main.h"

#include <linux/atomic.h>
#include <linux/cache.h>
#include <linux/errno.h>
#include <linux/if_ether.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include <linux/netlink.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/seq_file.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/stddef.h>
#include <linux/types.h>
#include <linux/workqueue.h>
#include <net/genetlink.h>
#include <net/netlink.h>
#include <uapi/linux/batadv_packet.h>
#include <uapi/linux/batman_adv.h>

#include "bat_algo.h"
#include "bat_v_elp.h"
#include "bat_v_ogm.h"
#include "gateway_client.h"
#include "gateway_common.h"
#include "hard-interface.h"
#include "hash.h"
#include "log.h"
#include "netlink.h"
#include "originator.h"

static void batadv_v_iface_activate(struct batadv_hard_iface *hard_iface)
{
        struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
        struct batadv_hard_iface *primary_if;

        primary_if = batadv_primary_if_get_selected(bat_priv);

        if (primary_if) {
                batadv_v_elp_iface_activate(primary_if, hard_iface);
                batadv_hardif_put(primary_if);
        }

        /* B.A.T.M.A.N. V does not use any queuing mechanism, therefore it can
         * set the interface as ACTIVE right away, without any risk of race
         * condition
         */
        if (hard_iface->if_status == BATADV_IF_TO_BE_ACTIVATED)
                hard_iface->if_status = BATADV_IF_ACTIVE;
}

static int batadv_v_iface_enable(struct batadv_hard_iface *hard_iface)
{
        int ret;

        ret = batadv_v_elp_iface_enable(hard_iface);
        if (ret < 0)
                return ret;

        ret = batadv_v_ogm_iface_enable(hard_iface);
        if (ret < 0)
                batadv_v_elp_iface_disable(hard_iface);

        return ret;
}

static void batadv_v_iface_disable(struct batadv_hard_iface *hard_iface)
{
        batadv_v_ogm_iface_disable(hard_iface);
        batadv_v_elp_iface_disable(hard_iface);
}

static void batadv_v_primary_iface_set(struct batadv_hard_iface *hard_iface)
{
        batadv_v_elp_primary_iface_set(hard_iface);
        batadv_v_ogm_primary_iface_set(hard_iface);
}

/**
 * batadv_v_iface_update_mac() - react to hard-interface MAC address change
 * @hard_iface: the modified interface
 *
 * If the modified interface is the primary one, update the originator
 * address in the ELP and OGM messages to reflect the new MAC address.
 */
static void batadv_v_iface_update_mac(struct batadv_hard_iface *hard_iface)
{
        struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
        struct batadv_hard_iface *primary_if;

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

        batadv_v_primary_iface_set(hard_iface);
out:
        if (primary_if)
                batadv_hardif_put(primary_if);
}

static void
batadv_v_hardif_neigh_init(struct batadv_hardif_neigh_node *hardif_neigh)
{
        ewma_throughput_init(&hardif_neigh->bat_v.throughput);
        INIT_WORK(&hardif_neigh->bat_v.metric_work,
                  batadv_v_elp_throughput_metric_update);
}

#ifdef CONFIG_BATMAN_ADV_DEBUGFS
/**
 * batadv_v_orig_print_neigh() - print neighbors for the originator table
 * @orig_node: the orig_node for which the neighbors are printed
 * @if_outgoing: outgoing interface for these entries
 * @seq: debugfs table seq_file struct
 *
 * Must be called while holding an rcu lock.
 */
static void
batadv_v_orig_print_neigh(struct batadv_orig_node *orig_node,
                          struct batadv_hard_iface *if_outgoing,
                          struct seq_file *seq)
{
        struct batadv_neigh_node *neigh_node;
        struct batadv_neigh_ifinfo *n_ifinfo;

        hlist_for_each_entry_rcu(neigh_node, &orig_node->neigh_list, list) {
                n_ifinfo = batadv_neigh_ifinfo_get(neigh_node, if_outgoing);
                if (!n_ifinfo)
                        continue;

                seq_printf(seq, " %pM (%9u.%1u)",
                           neigh_node->addr,
                           n_ifinfo->bat_v.throughput / 10,
                           n_ifinfo->bat_v.throughput % 10);

                batadv_neigh_ifinfo_put(n_ifinfo);
        }
}

/**
 * batadv_v_hardif_neigh_print() - print a single ELP neighbour node
 * @seq: neighbour table seq_file struct
 * @hardif_neigh: hardif neighbour information
 */
static void
batadv_v_hardif_neigh_print(struct seq_file *seq,
                            struct batadv_hardif_neigh_node *hardif_neigh)
{
        int last_secs, last_msecs;
        u32 throughput;

        last_secs = jiffies_to_msecs(jiffies - hardif_neigh->last_seen) / 1000;
        last_msecs = jiffies_to_msecs(jiffies - hardif_neigh->last_seen) % 1000;
        throughput = ewma_throughput_read(&hardif_neigh->bat_v.throughput);

        seq_printf(seq, "%pM %4i.%03is (%9u.%1u) [%10s]\n",
                   hardif_neigh->addr, last_secs, last_msecs, throughput / 10,
                   throughput % 10, hardif_neigh->if_incoming->net_dev->name);
}

/**
 * batadv_v_neigh_print() - print the single hop neighbour list
 * @bat_priv: the bat priv with all the soft interface information
 * @seq: neighbour table seq_file struct
 */
static void batadv_v_neigh_print(struct batadv_priv *bat_priv,
                                 struct seq_file *seq)
{
        struct net_device *net_dev = (struct net_device *)seq->private;
        struct batadv_hardif_neigh_node *hardif_neigh;
        struct batadv_hard_iface *hard_iface;
        int batman_count = 0;

        seq_puts(seq,
                 "  Neighbor        last-seen ( throughput) [        IF]\n");

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

                hlist_for_each_entry_rcu(hardif_neigh,
                                         &hard_iface->neigh_list, list) {
                        batadv_v_hardif_neigh_print(seq, hardif_neigh);
                        batman_count++;
                }
        }
        rcu_read_unlock();

        if (batman_count == 0)
                seq_puts(seq, "No batman nodes in range ...\n");
}
#endif

/**
 * batadv_v_neigh_dump_neigh() - Dump a neighbour into a message
 * @msg: Netlink message to dump into
 * @portid: Port making netlink request
 * @seq: Sequence number of netlink message
 * @hardif_neigh: Neighbour to dump
 *
 * Return: Error code, or 0 on success
 */
static int
batadv_v_neigh_dump_neigh(struct sk_buff *msg, u32 portid, u32 seq,
                          struct batadv_hardif_neigh_node *hardif_neigh)
{
        void *hdr;
        unsigned int last_seen_msecs;
        u32 throughput;

        last_seen_msecs = jiffies_to_msecs(jiffies - hardif_neigh->last_seen);
        throughput = ewma_throughput_read(&hardif_neigh->bat_v.throughput);
        throughput = throughput * 100;

        hdr = genlmsg_put(msg, portid, seq, &batadv_netlink_family, NLM_F_MULTI,
                          BATADV_CMD_GET_NEIGHBORS);
        if (!hdr)
                return -ENOBUFS;

        if (nla_put(msg, BATADV_ATTR_NEIGH_ADDRESS, ETH_ALEN,
                    hardif_neigh->addr) ||
            nla_put_u32(msg, BATADV_ATTR_HARD_IFINDEX,
                        hardif_neigh->if_incoming->net_dev->ifindex) ||
            nla_put_u32(msg, BATADV_ATTR_LAST_SEEN_MSECS,
                        last_seen_msecs) ||
            nla_put_u32(msg, BATADV_ATTR_THROUGHPUT, throughput))
                goto nla_put_failure;

        genlmsg_end(msg, hdr);
        return 0;

 nla_put_failure:
        genlmsg_cancel(msg, hdr);
        return -EMSGSIZE;
}

/**
 * batadv_v_neigh_dump_hardif() - Dump the  neighbours of a hard interface into
 *  a message
 * @msg: Netlink message to dump into
 * @portid: Port making netlink request
 * @seq: Sequence number of netlink message
 * @bat_priv: The bat priv with all the soft interface information
 * @hard_iface: The hard interface to be dumped
 * @idx_s: Entries to be skipped
 *
 * This function assumes the caller holds rcu_read_lock().
 *
 * Return: Error code, or 0 on success
 */
static int
batadv_v_neigh_dump_hardif(struct sk_buff *msg, u32 portid, u32 seq,
                           struct batadv_priv *bat_priv,
                           struct batadv_hard_iface *hard_iface,
                           int *idx_s)
{
        struct batadv_hardif_neigh_node *hardif_neigh;
        int idx = 0;

        hlist_for_each_entry_rcu(hardif_neigh,
                                 &hard_iface->neigh_list, list) {
                if (idx++ < *idx_s)
                        continue;

                if (batadv_v_neigh_dump_neigh(msg, portid, seq, hardif_neigh)) {
                        *idx_s = idx - 1;
                        return -EMSGSIZE;
                }
        }

        *idx_s = 0;
        return 0;
}

/**
 * batadv_v_neigh_dump() - Dump the neighbours of a hard interface  into a
 *  message
 * @msg: Netlink message to dump into
 * @cb: Control block containing additional options
 * @bat_priv: The bat priv with all the soft interface information
 * @single_hardif: Limit dumping to this hard interface
 */
static void
batadv_v_neigh_dump(struct sk_buff *msg, struct netlink_callback *cb,
                    struct batadv_priv *bat_priv,
                    struct batadv_hard_iface *single_hardif)
{
        struct batadv_hard_iface *hard_iface;
        int i_hardif = 0;
        int i_hardif_s = cb->args[0];
        int idx = cb->args[1];
        int portid = NETLINK_CB(cb->skb).portid;

        rcu_read_lock();
        if (single_hardif) {
                if (i_hardif_s == 0) {
                        if (batadv_v_neigh_dump_hardif(msg, portid,
                                                       cb->nlh->nlmsg_seq,
                                                       bat_priv, single_hardif,
                                                       &idx) == 0)
                                i_hardif++;
                }
        } else {
                list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
                        if (hard_iface->soft_iface != bat_priv->soft_iface)
                                continue;

                        if (i_hardif++ < i_hardif_s)
                                continue;

                        if (batadv_v_neigh_dump_hardif(msg, portid,
                                                       cb->nlh->nlmsg_seq,
                                                       bat_priv, hard_iface,
                                                       &idx)) {
                                i_hardif--;
                                break;
                        }
                }
        }
        rcu_read_unlock();

        cb->args[0] = i_hardif;
        cb->args[1] = idx;
}

#ifdef CONFIG_BATMAN_ADV_DEBUGFS
/**
 * batadv_v_orig_print() - print the originator table
 * @bat_priv: the bat priv with all the soft interface information
 * @seq: debugfs table seq_file struct
 * @if_outgoing: the outgoing interface for which this should be printed
 */
static void batadv_v_orig_print(struct batadv_priv *bat_priv,
                                struct seq_file *seq,
                                struct batadv_hard_iface *if_outgoing)
{
        struct batadv_neigh_node *neigh_node;
        struct batadv_hashtable *hash = bat_priv->orig_hash;
        int last_seen_msecs, last_seen_secs;
        struct batadv_orig_node *orig_node;
        struct batadv_neigh_ifinfo *n_ifinfo;
        unsigned long last_seen_jiffies;
        struct hlist_head *head;
        int batman_count = 0;
        u32 i;

        seq_puts(seq,
                 "  Originator      last-seen ( throughput)           Nexthop [outgoingIF]:   Potential nexthops ...\n");

        for (i = 0; i < hash->size; i++) {
                head = &hash->table[i];

                rcu_read_lock();
                hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
                        neigh_node = batadv_orig_router_get(orig_node,
                                                            if_outgoing);
                        if (!neigh_node)
                                continue;

                        n_ifinfo = batadv_neigh_ifinfo_get(neigh_node,
                                                           if_outgoing);
                        if (!n_ifinfo)
                                goto next;

                        last_seen_jiffies = jiffies - orig_node->last_seen;
                        last_seen_msecs = jiffies_to_msecs(last_seen_jiffies);
                        last_seen_secs = last_seen_msecs / 1000;
                        last_seen_msecs = last_seen_msecs % 1000;

                        seq_printf(seq, "%pM %4i.%03is (%9u.%1u) %pM [%10s]:",
                                   orig_node->orig, last_seen_secs,
                                   last_seen_msecs,
                                   n_ifinfo->bat_v.throughput / 10,
                                   n_ifinfo->bat_v.throughput % 10,
                                   neigh_node->addr,
                                   neigh_node->if_incoming->net_dev->name);

                        batadv_v_orig_print_neigh(orig_node, if_outgoing, seq);
                        seq_putc(seq, '\n');
                        batman_count++;

next:
                        batadv_neigh_node_put(neigh_node);
                        if (n_ifinfo)
                                batadv_neigh_ifinfo_put(n_ifinfo);
                }
                rcu_read_unlock();
        }

        if (batman_count == 0)
                seq_puts(seq, "No batman nodes in range ...\n");
}
#endif

/**
 * batadv_v_orig_dump_subentry() - Dump an originator subentry into a message
 * @msg: Netlink message to dump into
 * @portid: Port making netlink request
 * @seq: Sequence number of netlink message
 * @bat_priv: The bat priv with all the soft interface information
 * @if_outgoing: Limit dump to entries with this outgoing interface
 * @orig_node: Originator to dump
 * @neigh_node: Single hops neighbour
 * @best: Is the best originator
 *
 * Return: Error code, or 0 on success
 */
static int
batadv_v_orig_dump_subentry(struct sk_buff *msg, u32 portid, u32 seq,
                            struct batadv_priv *bat_priv,
                            struct batadv_hard_iface *if_outgoing,
                            struct batadv_orig_node *orig_node,
                            struct batadv_neigh_node *neigh_node,
                            bool best)
{
        struct batadv_neigh_ifinfo *n_ifinfo;
        unsigned int last_seen_msecs;
        u32 throughput;
        void *hdr;

        n_ifinfo = batadv_neigh_ifinfo_get(neigh_node, if_outgoing);
        if (!n_ifinfo)
                return 0;

        throughput = n_ifinfo->bat_v.throughput * 100;

        batadv_neigh_ifinfo_put(n_ifinfo);

        last_seen_msecs = jiffies_to_msecs(jiffies - orig_node->last_seen);

        if (if_outgoing != BATADV_IF_DEFAULT &&
            if_outgoing != neigh_node->if_incoming)
                return 0;

        hdr = genlmsg_put(msg, portid, seq, &batadv_netlink_family, NLM_F_MULTI,
                          BATADV_CMD_GET_ORIGINATORS);
        if (!hdr)
                return -ENOBUFS;

        if (nla_put(msg, BATADV_ATTR_ORIG_ADDRESS, ETH_ALEN, orig_node->orig) ||
            nla_put(msg, BATADV_ATTR_NEIGH_ADDRESS, ETH_ALEN,
                    neigh_node->addr) ||
            nla_put_u32(msg, BATADV_ATTR_HARD_IFINDEX,
                        neigh_node->if_incoming->net_dev->ifindex) ||
            nla_put_u32(msg, BATADV_ATTR_THROUGHPUT, throughput) ||
            nla_put_u32(msg, BATADV_ATTR_LAST_SEEN_MSECS,
                        last_seen_msecs))
                goto nla_put_failure;

        if (best && nla_put_flag(msg, BATADV_ATTR_FLAG_BEST))
                goto nla_put_failure;

        genlmsg_end(msg, hdr);
        return 0;

 nla_put_failure:
        genlmsg_cancel(msg, hdr);
        return -EMSGSIZE;
}

/**
 * batadv_v_orig_dump_entry() - Dump an originator entry into a message
 * @msg: Netlink message to dump into
 * @portid: Port making netlink request
 * @seq: Sequence number of netlink message
 * @bat_priv: The bat priv with all the soft interface information
 * @if_outgoing: Limit dump to entries with this outgoing interface
 * @orig_node: Originator to dump
 * @sub_s: Number of sub entries to skip
 *
 * This function assumes the caller holds rcu_read_lock().
 *
 * Return: Error code, or 0 on success
 */
static int
batadv_v_orig_dump_entry(struct sk_buff *msg, u32 portid, u32 seq,
                         struct batadv_priv *bat_priv,
                         struct batadv_hard_iface *if_outgoing,
                         struct batadv_orig_node *orig_node, int *sub_s)
{
        struct batadv_neigh_node *neigh_node_best;
        struct batadv_neigh_node *neigh_node;
        int sub = 0;
        bool best;

        neigh_node_best = batadv_orig_router_get(orig_node, if_outgoing);
        if (!neigh_node_best)
                goto out;

        hlist_for_each_entry_rcu(neigh_node, &orig_node->neigh_list, list) {
                if (sub++ < *sub_s)
                        continue;

                best = (neigh_node == neigh_node_best);

                if (batadv_v_orig_dump_subentry(msg, portid, seq, bat_priv,
                                                if_outgoing, orig_node,
                                                neigh_node, best)) {
                        batadv_neigh_node_put(neigh_node_best);

                        *sub_s = sub - 1;
                        return -EMSGSIZE;
                }
        }

 out:
        if (neigh_node_best)
                batadv_neigh_node_put(neigh_node_best);

        *sub_s = 0;
        return 0;
}

/**
 * batadv_v_orig_dump_bucket() - Dump an originator bucket into a message
 * @msg: Netlink message to dump into
 * @portid: Port making netlink request
 * @seq: Sequence number of netlink message
 * @bat_priv: The bat priv with all the soft interface information
 * @if_outgoing: Limit dump to entries with this outgoing interface
 * @head: Bucket to be dumped
 * @idx_s: Number of entries to be skipped
 * @sub: Number of sub entries to be skipped
 *
 * Return: Error code, or 0 on success
 */
static int
batadv_v_orig_dump_bucket(struct sk_buff *msg, u32 portid, u32 seq,
                          struct batadv_priv *bat_priv,
                          struct batadv_hard_iface *if_outgoing,
                          struct hlist_head *head, int *idx_s, int *sub)
{
        struct batadv_orig_node *orig_node;
        int idx = 0;

        rcu_read_lock();
        hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
                if (idx++ < *idx_s)
                        continue;

                if (batadv_v_orig_dump_entry(msg, portid, seq, bat_priv,
                                             if_outgoing, orig_node, sub)) {
                        rcu_read_unlock();
                        *idx_s = idx - 1;
                        return -EMSGSIZE;
                }
        }
        rcu_read_unlock();

        *idx_s = 0;
        *sub = 0;
        return 0;
}

/**
 * batadv_v_orig_dump() - Dump the originators into a message
 * @msg: Netlink message to dump into
 * @cb: Control block containing additional options
 * @bat_priv: The bat priv with all the soft interface information
 * @if_outgoing: Limit dump to entries with this outgoing interface
 */
static void
batadv_v_orig_dump(struct sk_buff *msg, struct netlink_callback *cb,
                   struct batadv_priv *bat_priv,
                   struct batadv_hard_iface *if_outgoing)
{
        struct batadv_hashtable *hash = bat_priv->orig_hash;
        struct hlist_head *head;
        int bucket = cb->args[0];
        int idx = cb->args[1];
        int sub = cb->args[2];
        int portid = NETLINK_CB(cb->skb).portid;

        while (bucket < hash->size) {
                head = &hash->table[bucket];

                if (batadv_v_orig_dump_bucket(msg, portid,
                                              cb->nlh->nlmsg_seq,
                                              bat_priv, if_outgoing, head, &idx,
                                              &sub))
                        break;

                bucket++;
        }

        cb->args[0] = bucket;
        cb->args[1] = idx;
        cb->args[2] = sub;
}

static int batadv_v_neigh_cmp(struct batadv_neigh_node *neigh1,
                              struct batadv_hard_iface *if_outgoing1,
                              struct batadv_neigh_node *neigh2,
                              struct batadv_hard_iface *if_outgoing2)
{
        struct batadv_neigh_ifinfo *ifinfo1, *ifinfo2;
        int ret = 0;

        ifinfo1 = batadv_neigh_ifinfo_get(neigh1, if_outgoing1);
        if (!ifinfo1)
                goto err_ifinfo1;

        ifinfo2 = batadv_neigh_ifinfo_get(neigh2, if_outgoing2);
        if (!ifinfo2)
                goto err_ifinfo2;

        ret = ifinfo1->bat_v.throughput - ifinfo2->bat_v.throughput;

        batadv_neigh_ifinfo_put(ifinfo2);
err_ifinfo2:
        batadv_neigh_ifinfo_put(ifinfo1);
err_ifinfo1:
        return ret;
}

static bool batadv_v_neigh_is_sob(struct batadv_neigh_node *neigh1,
                                  struct batadv_hard_iface *if_outgoing1,
                                  struct batadv_neigh_node *neigh2,
                                  struct batadv_hard_iface *if_outgoing2)
{
        struct batadv_neigh_ifinfo *ifinfo1, *ifinfo2;
        u32 threshold;
        bool ret = false;

        ifinfo1 = batadv_neigh_ifinfo_get(neigh1, if_outgoing1);
        if (!ifinfo1)
                goto err_ifinfo1;

        ifinfo2 = batadv_neigh_ifinfo_get(neigh2, if_outgoing2);
        if (!ifinfo2)
                goto err_ifinfo2;

        threshold = ifinfo1->bat_v.throughput / 4;
        threshold = ifinfo1->bat_v.throughput - threshold;

        ret = ifinfo2->bat_v.throughput > threshold;

        batadv_neigh_ifinfo_put(ifinfo2);
err_ifinfo2:
        batadv_neigh_ifinfo_put(ifinfo1);
err_ifinfo1:
        return ret;
}

/**
 * batadv_v_init_sel_class() - initialize GW selection class
 * @bat_priv: the bat priv with all the soft interface information
 */
static void batadv_v_init_sel_class(struct batadv_priv *bat_priv)
{
        /* set default throughput difference threshold to 5Mbps */
        atomic_set(&bat_priv->gw.sel_class, 50);
}

static ssize_t batadv_v_store_sel_class(struct batadv_priv *bat_priv,
                                        char *buff, size_t count)
{
        u32 old_class, class;

        if (!batadv_parse_throughput(bat_priv->soft_iface, buff,
                                     "B.A.T.M.A.N. V GW selection class",
                                     &class))
                return -EINVAL;

        old_class = atomic_read(&bat_priv->gw.sel_class);
        atomic_set(&bat_priv->gw.sel_class, class);

        if (old_class != class)
                batadv_gw_reselect(bat_priv);

        return count;
}

static ssize_t batadv_v_show_sel_class(struct batadv_priv *bat_priv, char *buff)
{
        u32 class = atomic_read(&bat_priv->gw.sel_class);

        return sprintf(buff, "%u.%u MBit\n", class / 10, class % 10);
}

/**
 * batadv_v_gw_throughput_get() - retrieve the GW-bandwidth for a given GW
 * @gw_node: the GW to retrieve the metric for
 * @bw: the pointer where the metric will be stored. The metric is computed as
 *  the minimum between the GW advertised throughput and the path throughput to
 *  it in the mesh
 *
 * Return: 0 on success, -1 on failure
 */
static int batadv_v_gw_throughput_get(struct batadv_gw_node *gw_node, u32 *bw)
{
        struct batadv_neigh_ifinfo *router_ifinfo = NULL;
        struct batadv_orig_node *orig_node;
        struct batadv_neigh_node *router;
        int ret = -1;

        orig_node = gw_node->orig_node;
        router = batadv_orig_router_get(orig_node, BATADV_IF_DEFAULT);
        if (!router)
                goto out;

        router_ifinfo = batadv_neigh_ifinfo_get(router, BATADV_IF_DEFAULT);
        if (!router_ifinfo)
                goto out;

        /* the GW metric is computed as the minimum between the path throughput
         * to reach the GW itself and the advertised bandwidth.
         * This gives us an approximation of the effective throughput that the
         * client can expect via this particular GW node
         */
        *bw = router_ifinfo->bat_v.throughput;
        *bw = min_t(u32, *bw, gw_node->bandwidth_down);

        ret = 0;
out:
        if (router)
                batadv_neigh_node_put(router);
        if (router_ifinfo)
                batadv_neigh_ifinfo_put(router_ifinfo);

        return ret;
}

/**
 * batadv_v_gw_get_best_gw_node() - retrieve the best GW node
 * @bat_priv: the bat priv with all the soft interface information
 *
 * Return: the GW node having the best GW-metric, NULL if no GW is known
 */
static struct batadv_gw_node *
batadv_v_gw_get_best_gw_node(struct batadv_priv *bat_priv)
{
        struct batadv_gw_node *gw_node, *curr_gw = NULL;
        u32 max_bw = 0, bw;

        rcu_read_lock();
        hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.gateway_list, list) {
                if (!kref_get_unless_zero(&gw_node->refcount))
                        continue;

                if (batadv_v_gw_throughput_get(gw_node, &bw) < 0)
                        goto next;

                if (curr_gw && bw <= max_bw)
                        goto next;

                if (curr_gw)
                        batadv_gw_node_put(curr_gw);

                curr_gw = gw_node;
                kref_get(&curr_gw->refcount);
                max_bw = bw;

next:
                batadv_gw_node_put(gw_node);
        }
        rcu_read_unlock();

        return curr_gw;
}

/**
 * batadv_v_gw_is_eligible() - check if a originator would be selected as GW
 * @bat_priv: the bat priv with all the soft interface information
 * @curr_gw_orig: originator representing the currently selected GW
 * @orig_node: the originator representing the new candidate
 *
 * Return: true if orig_node can be selected as current GW, false otherwise
 */
static bool batadv_v_gw_is_eligible(struct batadv_priv *bat_priv,
                                    struct batadv_orig_node *curr_gw_orig,
                                    struct batadv_orig_node *orig_node)
{
        struct batadv_gw_node *curr_gw, *orig_gw = NULL;
        u32 gw_throughput, orig_throughput, threshold;
        bool ret = false;

        threshold = atomic_read(&bat_priv->gw.sel_class);

        curr_gw = batadv_gw_node_get(bat_priv, curr_gw_orig);
        if (!curr_gw) {
                ret = true;
                goto out;
        }

        if (batadv_v_gw_throughput_get(curr_gw, &gw_throughput) < 0) {
                ret = true;
                goto out;
        }

        orig_gw = batadv_gw_node_get(bat_priv, orig_node);
        if (!orig_gw)
                goto out;

        if (batadv_v_gw_throughput_get(orig_gw, &orig_throughput) < 0)
                goto out;

        if (orig_throughput < gw_throughput)
                goto out;

        if ((orig_throughput - gw_throughput) < threshold)
                goto out;

        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                   "Restarting gateway selection: better gateway found (throughput curr: %u, throughput new: %u)\n",
                   gw_throughput, orig_throughput);

        ret = true;
out:
        if (curr_gw)
                batadv_gw_node_put(curr_gw);
        if (orig_gw)
                batadv_gw_node_put(orig_gw);

        return ret;
}

#ifdef CONFIG_BATMAN_ADV_DEBUGFS
/* fails if orig_node has no router */
static int batadv_v_gw_write_buffer_text(struct batadv_priv *bat_priv,
                                         struct seq_file *seq,
                                         const struct batadv_gw_node *gw_node)
{
        struct batadv_gw_node *curr_gw;
        struct batadv_neigh_node *router;
        struct batadv_neigh_ifinfo *router_ifinfo = NULL;
        int ret = -1;

        router = batadv_orig_router_get(gw_node->orig_node, BATADV_IF_DEFAULT);
        if (!router)
                goto out;

        router_ifinfo = batadv_neigh_ifinfo_get(router, BATADV_IF_DEFAULT);
        if (!router_ifinfo)
                goto out;

        curr_gw = batadv_gw_get_selected_gw_node(bat_priv);

        seq_printf(seq, "%s %pM (%9u.%1u) %pM [%10s]: %u.%u/%u.%u MBit\n",
                   (curr_gw == gw_node ? "=>" : "  "),
                   gw_node->orig_node->orig,
                   router_ifinfo->bat_v.throughput / 10,
                   router_ifinfo->bat_v.throughput % 10, router->addr,
                   router->if_incoming->net_dev->name,
                   gw_node->bandwidth_down / 10,
                   gw_node->bandwidth_down % 10,
                   gw_node->bandwidth_up / 10,
                   gw_node->bandwidth_up % 10);
        ret = seq_has_overflowed(seq) ? -1 : 0;

        if (curr_gw)
                batadv_gw_node_put(curr_gw);
out:
        if (router_ifinfo)
                batadv_neigh_ifinfo_put(router_ifinfo);
        if (router)
                batadv_neigh_node_put(router);
        return ret;
}

/**
 * batadv_v_gw_print() - print the gateway list
 * @bat_priv: the bat priv with all the soft interface information
 * @seq: gateway table seq_file struct
 */
static void batadv_v_gw_print(struct batadv_priv *bat_priv,
                              struct seq_file *seq)
{
        struct batadv_gw_node *gw_node;
        int gw_count = 0;

        seq_puts(seq,
                 "      Gateway        ( throughput)           Nexthop [outgoingIF]: advertised uplink bandwidth\n");

        rcu_read_lock();
        hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.gateway_list, list) {
                /* fails if orig_node has no router */
                if (batadv_v_gw_write_buffer_text(bat_priv, seq, gw_node) < 0)
                        continue;

                gw_count++;
        }
        rcu_read_unlock();

        if (gw_count == 0)
                seq_puts(seq, "No gateways in range ...\n");
}
#endif

/**
 * batadv_v_gw_dump_entry() - Dump a gateway into a message
 * @msg: Netlink message to dump into
 * @portid: Port making netlink request
 * @cb: Control block containing additional options
 * @bat_priv: The bat priv with all the soft interface information
 * @gw_node: Gateway to be dumped
 *
 * Return: Error code, or 0 on success
 */
static int batadv_v_gw_dump_entry(struct sk_buff *msg, u32 portid,
                                  struct netlink_callback *cb,
                                  struct batadv_priv *bat_priv,
                                  struct batadv_gw_node *gw_node)
{
        struct batadv_neigh_ifinfo *router_ifinfo = NULL;
        struct batadv_neigh_node *router;
        struct batadv_gw_node *curr_gw = NULL;
        int ret = 0;
        void *hdr;

        router = batadv_orig_router_get(gw_node->orig_node, BATADV_IF_DEFAULT);
        if (!router)
                goto out;

        router_ifinfo = batadv_neigh_ifinfo_get(router, BATADV_IF_DEFAULT);
        if (!router_ifinfo)
                goto out;

        curr_gw = batadv_gw_get_selected_gw_node(bat_priv);

        hdr = genlmsg_put(msg, portid, cb->nlh->nlmsg_seq,
                          &batadv_netlink_family, NLM_F_MULTI,
                          BATADV_CMD_GET_GATEWAYS);
        if (!hdr) {
                ret = -ENOBUFS;
                goto out;
        }

        genl_dump_check_consistent(cb, hdr);

        ret = -EMSGSIZE;

        if (curr_gw == gw_node) {
                if (nla_put_flag(msg, BATADV_ATTR_FLAG_BEST)) {
                        genlmsg_cancel(msg, hdr);
                        goto out;
                }
        }

        if (nla_put(msg, BATADV_ATTR_ORIG_ADDRESS, ETH_ALEN,
                    gw_node->orig_node->orig)) {
                genlmsg_cancel(msg, hdr);
                goto out;
        }

        if (nla_put_u32(msg, BATADV_ATTR_THROUGHPUT,
                        router_ifinfo->bat_v.throughput)) {
                genlmsg_cancel(msg, hdr);
                goto out;
        }

        if (nla_put(msg, BATADV_ATTR_ROUTER, ETH_ALEN, router->addr)) {
                genlmsg_cancel(msg, hdr);
                goto out;
        }

        if (nla_put_string(msg, BATADV_ATTR_HARD_IFNAME,
                           router->if_incoming->net_dev->name)) {
                genlmsg_cancel(msg, hdr);
                goto out;
        }

        if (nla_put_u32(msg, BATADV_ATTR_BANDWIDTH_DOWN,
                        gw_node->bandwidth_down)) {
                genlmsg_cancel(msg, hdr);
                goto out;
        }

        if (nla_put_u32(msg, BATADV_ATTR_BANDWIDTH_UP, gw_node->bandwidth_up)) {
                genlmsg_cancel(msg, hdr);
                goto out;
        }

        genlmsg_end(msg, hdr);
        ret = 0;

out:
        if (curr_gw)
                batadv_gw_node_put(curr_gw);
        if (router_ifinfo)
                batadv_neigh_ifinfo_put(router_ifinfo);
        if (router)
                batadv_neigh_node_put(router);
        return ret;
}

/**
 * batadv_v_gw_dump() - Dump gateways into a message
 * @msg: Netlink message to dump into
 * @cb: Control block containing additional options
 * @bat_priv: The bat priv with all the soft interface information
 */
static void batadv_v_gw_dump(struct sk_buff *msg, struct netlink_callback *cb,
                             struct batadv_priv *bat_priv)
{
        int portid = NETLINK_CB(cb->skb).portid;
        struct batadv_gw_node *gw_node;
        int idx_skip = cb->args[0];
        int idx = 0;

        spin_lock_bh(&bat_priv->gw.list_lock);
        cb->seq = bat_priv->gw.generation << 1 | 1;

        hlist_for_each_entry(gw_node, &bat_priv->gw.gateway_list, list) {
                if (idx++ < idx_skip)
                        continue;

                if (batadv_v_gw_dump_entry(msg, portid, cb, bat_priv,
                                           gw_node)) {
                        idx_skip = idx - 1;
                        goto unlock;
                }
        }

        idx_skip = idx;
unlock:
        spin_unlock_bh(&bat_priv->gw.list_lock);

        cb->args[0] = idx_skip;
}

static struct batadv_algo_ops batadv_batman_v __read_mostly = {
        .name = "BATMAN_V",
        .iface = {
                .activate = batadv_v_iface_activate,
                .enable = batadv_v_iface_enable,
                .disable = batadv_v_iface_disable,
                .update_mac = batadv_v_iface_update_mac,
                .primary_set = batadv_v_primary_iface_set,
        },
        .neigh = {
                .hardif_init = batadv_v_hardif_neigh_init,
                .cmp = batadv_v_neigh_cmp,
                .is_similar_or_better = batadv_v_neigh_is_sob,
#ifdef CONFIG_BATMAN_ADV_DEBUGFS
                .print = batadv_v_neigh_print,
#endif
                .dump = batadv_v_neigh_dump,
        },
        .orig = {
#ifdef CONFIG_BATMAN_ADV_DEBUGFS
                .print = batadv_v_orig_print,
#endif
                .dump = batadv_v_orig_dump,
        },
        .gw = {
                .init_sel_class = batadv_v_init_sel_class,
                .store_sel_class = batadv_v_store_sel_class,
                .show_sel_class = batadv_v_show_sel_class,
                .get_best_gw_node = batadv_v_gw_get_best_gw_node,
                .is_eligible = batadv_v_gw_is_eligible,
#ifdef CONFIG_BATMAN_ADV_DEBUGFS
                .print = batadv_v_gw_print,
#endif
                .dump = batadv_v_gw_dump,
        },
};

/**
 * batadv_v_hardif_init() - initialize the algorithm specific fields in the
 *  hard-interface object
 * @hard_iface: the hard-interface to initialize
 */
void batadv_v_hardif_init(struct batadv_hard_iface *hard_iface)
{
        /* enable link throughput auto-detection by setting the throughput
         * override to zero
         */
        atomic_set(&hard_iface->bat_v.throughput_override, 0);
        atomic_set(&hard_iface->bat_v.elp_interval, 500);

        hard_iface->bat_v.aggr_len = 0;
        skb_queue_head_init(&hard_iface->bat_v.aggr_list);
        INIT_DELAYED_WORK(&hard_iface->bat_v.aggr_wq,
                          batadv_v_ogm_aggr_work);
}

/**
 * batadv_v_mesh_init() - initialize the B.A.T.M.A.N. V private resources for a
 *  mesh
 * @bat_priv: the object representing the mesh interface to initialise
 *
 * Return: 0 on success or a negative error code otherwise
 */
int batadv_v_mesh_init(struct batadv_priv *bat_priv)
{
        int ret = 0;

        ret = batadv_v_ogm_init(bat_priv);
        if (ret < 0)
                return ret;

        return 0;
}

/**
 * batadv_v_mesh_free() - free the B.A.T.M.A.N. V private resources for a mesh
 * @bat_priv: the object representing the mesh interface to free
 */
void batadv_v_mesh_free(struct batadv_priv *bat_priv)
{
        batadv_v_ogm_free(bat_priv);
}

/**
 * batadv_v_init() - B.A.T.M.A.N. V initialization function
 *
 * Description: Takes care of initializing all the subcomponents.
 * It is invoked upon module load only.
 *
 * Return: 0 on success or a negative error code otherwise
 */
int __init batadv_v_init(void)
{
        int ret;

        /* B.A.T.M.A.N. V echo location protocol packet  */
        ret = batadv_recv_handler_register(BATADV_ELP,
                                           batadv_v_elp_packet_recv);
        if (ret < 0)
                return ret;

        ret = batadv_recv_handler_register(BATADV_OGM2,
                                           batadv_v_ogm_packet_recv);
        if (ret < 0)
                goto elp_unregister;

        ret = batadv_algo_register(&batadv_batman_v);
        if (ret < 0)
                goto ogm_unregister;

        return ret;

ogm_unregister:
        batadv_recv_handler_unregister(BATADV_OGM2);

elp_unregister:
        batadv_recv_handler_unregister(BATADV_ELP);

        return ret;
}