Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus

[linux-2.6.git] / net / batman-adv / bat_iv_ogm.c

/* 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 "translation-table.h"
#include "originator.h"
#include "routing.h"
#include "gateway_common.h"
#include "gateway_client.h"
#include "hard-interface.h"
#include "send.h"
#include "bat_algo.h"
#include "network-coding.h"

/**
 * batadv_ring_buffer_set - update the ring buffer with the given value
 * @lq_recv: pointer to the ring buffer
 * @lq_index: index to store the value at
 * @value: value to store in the ring buffer
 */
static void batadv_ring_buffer_set(uint8_t lq_recv[], uint8_t *lq_index,
                                   uint8_t value)
{
        lq_recv[*lq_index] = value;
        *lq_index = (*lq_index + 1) % BATADV_TQ_GLOBAL_WINDOW_SIZE;
}

/**
 * batadv_ring_buffer_set - compute the average of all non-zero values stored
 * in the given ring buffer
 * @lq_recv: pointer to the ring buffer
 *
 * Returns computed average value.
 */
static uint8_t batadv_ring_buffer_avg(const uint8_t lq_recv[])
{
        const uint8_t *ptr;
        uint16_t count = 0, i = 0, sum = 0;

        ptr = lq_recv;

        while (i < BATADV_TQ_GLOBAL_WINDOW_SIZE) {
                if (*ptr != 0) {
                        count++;
                        sum += *ptr;
                }

                i++;
                ptr++;
        }

        if (count == 0)
                return 0;

        return (uint8_t)(sum / count);
}

/*
 * batadv_dup_status - duplicate status
 * @BATADV_NO_DUP: the packet is a duplicate
 * @BATADV_ORIG_DUP: OGM is a duplicate in the originator (but not for the
 *  neighbor)
 * @BATADV_NEIGH_DUP: OGM is a duplicate for the neighbor
 * @BATADV_PROTECTED: originator is currently protected (after reboot)
 */
enum batadv_dup_status {
        BATADV_NO_DUP = 0,
        BATADV_ORIG_DUP,
        BATADV_NEIGH_DUP,
        BATADV_PROTECTED,
};

static struct batadv_neigh_node *
batadv_iv_ogm_neigh_new(struct batadv_hard_iface *hard_iface,
                        const uint8_t *neigh_addr,
                        struct batadv_orig_node *orig_node,
                        struct batadv_orig_node *orig_neigh)
{
        struct batadv_neigh_node *neigh_node;

        neigh_node = batadv_neigh_node_new(hard_iface, neigh_addr);
        if (!neigh_node)
                goto out;

        INIT_LIST_HEAD(&neigh_node->bonding_list);

        neigh_node->orig_node = orig_neigh;
        neigh_node->if_incoming = hard_iface;

        spin_lock_bh(&orig_node->neigh_list_lock);
        hlist_add_head_rcu(&neigh_node->list, &orig_node->neigh_list);
        spin_unlock_bh(&orig_node->neigh_list_lock);

out:
        return neigh_node;
}

static int batadv_iv_ogm_iface_enable(struct batadv_hard_iface *hard_iface)
{
        struct batadv_ogm_packet *batadv_ogm_packet;
        unsigned char *ogm_buff;
        uint32_t random_seqno;
        int res = -ENOMEM;

        /* randomize initial seqno to avoid collision */
        get_random_bytes(&random_seqno, sizeof(random_seqno));
        atomic_set(&hard_iface->bat_iv.ogm_seqno, random_seqno);

        hard_iface->bat_iv.ogm_buff_len = BATADV_OGM_HLEN;
        ogm_buff = kmalloc(hard_iface->bat_iv.ogm_buff_len, GFP_ATOMIC);
        if (!ogm_buff)
                goto out;

        hard_iface->bat_iv.ogm_buff = ogm_buff;

        batadv_ogm_packet = (struct batadv_ogm_packet *)ogm_buff;
        batadv_ogm_packet->header.packet_type = BATADV_IV_OGM;
        batadv_ogm_packet->header.version = BATADV_COMPAT_VERSION;
        batadv_ogm_packet->header.ttl = 2;
        batadv_ogm_packet->flags = BATADV_NO_FLAGS;
        batadv_ogm_packet->tq = BATADV_TQ_MAX_VALUE;
        batadv_ogm_packet->tt_num_changes = 0;
        batadv_ogm_packet->ttvn = 0;

        res = 0;

out:
        return res;
}

static void batadv_iv_ogm_iface_disable(struct batadv_hard_iface *hard_iface)
{
        kfree(hard_iface->bat_iv.ogm_buff);
        hard_iface->bat_iv.ogm_buff = NULL;
}

static void batadv_iv_ogm_iface_update_mac(struct batadv_hard_iface *hard_iface)
{
        struct batadv_ogm_packet *batadv_ogm_packet;
        unsigned char *ogm_buff = hard_iface->bat_iv.ogm_buff;

        batadv_ogm_packet = (struct batadv_ogm_packet *)ogm_buff;
        memcpy(batadv_ogm_packet->orig,
               hard_iface->net_dev->dev_addr, ETH_ALEN);
        memcpy(batadv_ogm_packet->prev_sender,
               hard_iface->net_dev->dev_addr, ETH_ALEN);
}

static void
batadv_iv_ogm_primary_iface_set(struct batadv_hard_iface *hard_iface)
{
        struct batadv_ogm_packet *batadv_ogm_packet;
        unsigned char *ogm_buff = hard_iface->bat_iv.ogm_buff;

        batadv_ogm_packet = (struct batadv_ogm_packet *)ogm_buff;
        batadv_ogm_packet->flags = BATADV_PRIMARIES_FIRST_HOP;
        batadv_ogm_packet->header.ttl = BATADV_TTL;
}

/* when do we schedule our own ogm to be sent */
static unsigned long
batadv_iv_ogm_emit_send_time(const struct batadv_priv *bat_priv)
{
        unsigned int msecs;

        msecs = atomic_read(&bat_priv->orig_interval) - BATADV_JITTER;
        msecs += prandom_u32() % (2 * BATADV_JITTER);

        return jiffies + msecs_to_jiffies(msecs);
}

/* when do we schedule a ogm packet to be sent */
static unsigned long batadv_iv_ogm_fwd_send_time(void)
{
        return jiffies + msecs_to_jiffies(prandom_u32() % (BATADV_JITTER / 2));
}

/* apply hop penalty for a normal link */
static uint8_t batadv_hop_penalty(uint8_t tq,
                                  const struct batadv_priv *bat_priv)
{
        int hop_penalty = atomic_read(&bat_priv->hop_penalty);
        int new_tq;

        new_tq = tq * (BATADV_TQ_MAX_VALUE - hop_penalty);
        new_tq /= BATADV_TQ_MAX_VALUE;

        return new_tq;
}

/* is there another aggregated packet here? */
static int batadv_iv_ogm_aggr_packet(int buff_pos, int packet_len,
                                     int tt_num_changes)
{
        int next_buff_pos = 0;

        next_buff_pos += buff_pos + BATADV_OGM_HLEN;
        next_buff_pos += batadv_tt_len(tt_num_changes);

        return (next_buff_pos <= packet_len) &&
               (next_buff_pos <= BATADV_MAX_AGGREGATION_BYTES);
}

/* send a batman ogm to a given interface */
static void batadv_iv_ogm_send_to_if(struct batadv_forw_packet *forw_packet,
                                     struct batadv_hard_iface *hard_iface)
{
        struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
        char *fwd_str;
        uint8_t packet_num;
        int16_t buff_pos;
        struct batadv_ogm_packet *batadv_ogm_packet;
        struct sk_buff *skb;
        uint8_t *packet_pos;

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

        packet_num = 0;
        buff_pos = 0;
        packet_pos = forw_packet->skb->data;
        batadv_ogm_packet = (struct batadv_ogm_packet *)packet_pos;

        /* adjust all flags and log packets */
        while (batadv_iv_ogm_aggr_packet(buff_pos, forw_packet->packet_len,
                                         batadv_ogm_packet->tt_num_changes)) {
                /* we might have aggregated direct link packets with an
                 * ordinary base packet
                 */
                if (forw_packet->direct_link_flags & BIT(packet_num) &&
                    forw_packet->if_incoming == hard_iface)
                        batadv_ogm_packet->flags |= BATADV_DIRECTLINK;
                else
                        batadv_ogm_packet->flags &= ~BATADV_DIRECTLINK;

                if (packet_num > 0 || !forw_packet->own)
                        fwd_str = "Forwarding";
                else
                        fwd_str = "Sending own";

                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "%s %spacket (originator %pM, seqno %u, TQ %d, TTL %d, IDF %s, ttvn %d) on interface %s [%pM]\n",
                           fwd_str, (packet_num > 0 ? "aggregated " : ""),
                           batadv_ogm_packet->orig,
                           ntohl(batadv_ogm_packet->seqno),
                           batadv_ogm_packet->tq, batadv_ogm_packet->header.ttl,
                           (batadv_ogm_packet->flags & BATADV_DIRECTLINK ?
                            "on" : "off"),
                           batadv_ogm_packet->ttvn, hard_iface->net_dev->name,
                           hard_iface->net_dev->dev_addr);

                buff_pos += BATADV_OGM_HLEN;
                buff_pos += batadv_tt_len(batadv_ogm_packet->tt_num_changes);
                packet_num++;
                packet_pos = forw_packet->skb->data + buff_pos;
                batadv_ogm_packet = (struct batadv_ogm_packet *)packet_pos;
        }

        /* create clone because function is called more than once */
        skb = skb_clone(forw_packet->skb, GFP_ATOMIC);
        if (skb) {
                batadv_inc_counter(bat_priv, BATADV_CNT_MGMT_TX);
                batadv_add_counter(bat_priv, BATADV_CNT_MGMT_TX_BYTES,
                                   skb->len + ETH_HLEN);
                batadv_send_skb_packet(skb, hard_iface, batadv_broadcast_addr);
        }
}

/* send a batman ogm packet */
static void batadv_iv_ogm_emit(struct batadv_forw_packet *forw_packet)
{
        struct batadv_hard_iface *hard_iface;
        struct net_device *soft_iface;
        struct batadv_priv *bat_priv;
        struct batadv_hard_iface *primary_if = NULL;
        struct batadv_ogm_packet *batadv_ogm_packet;
        unsigned char directlink;
        uint8_t *packet_pos;

        packet_pos = forw_packet->skb->data;
        batadv_ogm_packet = (struct batadv_ogm_packet *)packet_pos;
        directlink = (batadv_ogm_packet->flags & BATADV_DIRECTLINK ? 1 : 0);

        if (!forw_packet->if_incoming) {
                pr_err("Error - can't forward packet: incoming iface not specified\n");
                goto out;
        }

        soft_iface = forw_packet->if_incoming->soft_iface;
        bat_priv = netdev_priv(soft_iface);

        if (forw_packet->if_incoming->if_status != BATADV_IF_ACTIVE)
                goto out;

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

        /* multihomed peer assumed
         * non-primary OGMs are only broadcasted on their interface
         */
        if ((directlink && (batadv_ogm_packet->header.ttl == 1)) ||
            (forw_packet->own && (forw_packet->if_incoming != primary_if))) {
                /* FIXME: what about aggregated packets ? */
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "%s packet (originator %pM, seqno %u, TTL %d) on interface %s [%pM]\n",
                           (forw_packet->own ? "Sending own" : "Forwarding"),
                           batadv_ogm_packet->orig,
                           ntohl(batadv_ogm_packet->seqno),
                           batadv_ogm_packet->header.ttl,
                           forw_packet->if_incoming->net_dev->name,
                           forw_packet->if_incoming->net_dev->dev_addr);

                /* skb is only used once and than forw_packet is free'd */
                batadv_send_skb_packet(forw_packet->skb,
                                       forw_packet->if_incoming,
                                       batadv_broadcast_addr);
                forw_packet->skb = NULL;

                goto out;
        }

        /* broadcast on every interface */
        rcu_read_lock();
        list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
                if (hard_iface->soft_iface != soft_iface)
                        continue;

                batadv_iv_ogm_send_to_if(forw_packet, hard_iface);
        }
        rcu_read_unlock();

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

/* return true if new_packet can be aggregated with forw_packet */
static bool
batadv_iv_ogm_can_aggregate(const struct batadv_ogm_packet *new_bat_ogm_packet,
                            struct batadv_priv *bat_priv,
                            int packet_len, unsigned long send_time,
                            bool directlink,
                            const struct batadv_hard_iface *if_incoming,
                            const struct batadv_forw_packet *forw_packet)
{
        struct batadv_ogm_packet *batadv_ogm_packet;
        int aggregated_bytes = forw_packet->packet_len + packet_len;
        struct batadv_hard_iface *primary_if = NULL;
        bool res = false;
        unsigned long aggregation_end_time;

        batadv_ogm_packet = (struct batadv_ogm_packet *)forw_packet->skb->data;
        aggregation_end_time = send_time;
        aggregation_end_time += msecs_to_jiffies(BATADV_MAX_AGGREGATION_MS);

        /* we can aggregate the current packet to this aggregated packet
         * if:
         *
         * - the send time is within our MAX_AGGREGATION_MS time
         * - the resulting packet wont be bigger than
         *   MAX_AGGREGATION_BYTES
         */
        if (time_before(send_time, forw_packet->send_time) &&
            time_after_eq(aggregation_end_time, forw_packet->send_time) &&
            (aggregated_bytes <= BATADV_MAX_AGGREGATION_BYTES)) {
                /* check aggregation compatibility
                 * -> direct link packets are broadcasted on
                 *    their interface only
                 * -> aggregate packet if the current packet is
                 *    a "global" packet as well as the base
                 *    packet
                 */
                primary_if = batadv_primary_if_get_selected(bat_priv);
                if (!primary_if)
                        goto out;

                /* packets without direct link flag and high TTL
                 * are flooded through the net
                 */
                if ((!directlink) &&
                    (!(batadv_ogm_packet->flags & BATADV_DIRECTLINK)) &&
                    (batadv_ogm_packet->header.ttl != 1) &&

                    /* own packets originating non-primary
                     * interfaces leave only that interface
                     */
                    ((!forw_packet->own) ||
                     (forw_packet->if_incoming == primary_if))) {
                        res = true;
                        goto out;
                }

                /* if the incoming packet is sent via this one
                 * interface only - we still can aggregate
                 */
                if ((directlink) &&
                    (new_bat_ogm_packet->header.ttl == 1) &&
                    (forw_packet->if_incoming == if_incoming) &&

                    /* packets from direct neighbors or
                     * own secondary interface packets
                     * (= secondary interface packets in general)
                     */
                    (batadv_ogm_packet->flags & BATADV_DIRECTLINK ||
                     (forw_packet->own &&
                      forw_packet->if_incoming != primary_if))) {
                        res = true;
                        goto out;
                }
        }

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

/* create a new aggregated packet and add this packet to it */
static void batadv_iv_ogm_aggregate_new(const unsigned char *packet_buff,
                                        int packet_len, unsigned long send_time,
                                        bool direct_link,
                                        struct batadv_hard_iface *if_incoming,
                                        int own_packet)
{
        struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
        struct batadv_forw_packet *forw_packet_aggr;
        unsigned char *skb_buff;
        unsigned int skb_size;

        if (!atomic_inc_not_zero(&if_incoming->refcount))
                return;

        /* own packet should always be scheduled */
        if (!own_packet) {
                if (!batadv_atomic_dec_not_zero(&bat_priv->batman_queue_left)) {
                        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                                   "batman packet queue full\n");
                        goto out;
                }
        }

        forw_packet_aggr = kmalloc(sizeof(*forw_packet_aggr), GFP_ATOMIC);
        if (!forw_packet_aggr) {
                if (!own_packet)
                        atomic_inc(&bat_priv->batman_queue_left);
                goto out;
        }

        if ((atomic_read(&bat_priv->aggregated_ogms)) &&
            (packet_len < BATADV_MAX_AGGREGATION_BYTES))
                skb_size = BATADV_MAX_AGGREGATION_BYTES;
        else
                skb_size = packet_len;

        skb_size += ETH_HLEN;

        forw_packet_aggr->skb = netdev_alloc_skb_ip_align(NULL, skb_size);
        if (!forw_packet_aggr->skb) {
                if (!own_packet)
                        atomic_inc(&bat_priv->batman_queue_left);
                kfree(forw_packet_aggr);
                goto out;
        }
        skb_reserve(forw_packet_aggr->skb, ETH_HLEN);

        skb_buff = skb_put(forw_packet_aggr->skb, packet_len);
        forw_packet_aggr->packet_len = packet_len;
        memcpy(skb_buff, packet_buff, packet_len);

        forw_packet_aggr->own = own_packet;
        forw_packet_aggr->if_incoming = if_incoming;
        forw_packet_aggr->num_packets = 0;
        forw_packet_aggr->direct_link_flags = BATADV_NO_FLAGS;
        forw_packet_aggr->send_time = send_time;

        /* save packet direct link flag status */
        if (direct_link)
                forw_packet_aggr->direct_link_flags |= 1;

        /* add new packet to packet list */
        spin_lock_bh(&bat_priv->forw_bat_list_lock);
        hlist_add_head(&forw_packet_aggr->list, &bat_priv->forw_bat_list);
        spin_unlock_bh(&bat_priv->forw_bat_list_lock);

        /* start timer for this packet */
        INIT_DELAYED_WORK(&forw_packet_aggr->delayed_work,
                          batadv_send_outstanding_bat_ogm_packet);
        queue_delayed_work(batadv_event_workqueue,
                           &forw_packet_aggr->delayed_work,
                           send_time - jiffies);

        return;
out:
        batadv_hardif_free_ref(if_incoming);
}

/* aggregate a new packet into the existing ogm packet */
static void batadv_iv_ogm_aggregate(struct batadv_forw_packet *forw_packet_aggr,
                                    const unsigned char *packet_buff,
                                    int packet_len, bool direct_link)
{
        unsigned char *skb_buff;
        unsigned long new_direct_link_flag;

        skb_buff = skb_put(forw_packet_aggr->skb, packet_len);
        memcpy(skb_buff, packet_buff, packet_len);
        forw_packet_aggr->packet_len += packet_len;
        forw_packet_aggr->num_packets++;

        /* save packet direct link flag status */
        if (direct_link) {
                new_direct_link_flag = BIT(forw_packet_aggr->num_packets);
                forw_packet_aggr->direct_link_flags |= new_direct_link_flag;
        }
}

static void batadv_iv_ogm_queue_add(struct batadv_priv *bat_priv,
                                    unsigned char *packet_buff,
                                    int packet_len,
                                    struct batadv_hard_iface *if_incoming,
                                    int own_packet, unsigned long send_time)
{
        /* _aggr -> pointer to the packet we want to aggregate with
         * _pos -> pointer to the position in the queue
         */
        struct batadv_forw_packet *forw_packet_aggr = NULL;
        struct batadv_forw_packet *forw_packet_pos = NULL;
        struct batadv_ogm_packet *batadv_ogm_packet;
        bool direct_link;
        unsigned long max_aggregation_jiffies;

        batadv_ogm_packet = (struct batadv_ogm_packet *)packet_buff;
        direct_link = batadv_ogm_packet->flags & BATADV_DIRECTLINK ? 1 : 0;
        max_aggregation_jiffies = msecs_to_jiffies(BATADV_MAX_AGGREGATION_MS);

        /* find position for the packet in the forward queue */
        spin_lock_bh(&bat_priv->forw_bat_list_lock);
        /* own packets are not to be aggregated */
        if ((atomic_read(&bat_priv->aggregated_ogms)) && (!own_packet)) {
                hlist_for_each_entry(forw_packet_pos,
                                     &bat_priv->forw_bat_list, list) {
                        if (batadv_iv_ogm_can_aggregate(batadv_ogm_packet,
                                                        bat_priv, packet_len,
                                                        send_time, direct_link,
                                                        if_incoming,
                                                        forw_packet_pos)) {
                                forw_packet_aggr = forw_packet_pos;
                                break;
                        }
                }
        }

        /* nothing to aggregate with - either aggregation disabled or no
         * suitable aggregation packet found
         */
        if (!forw_packet_aggr) {
                /* the following section can run without the lock */
                spin_unlock_bh(&bat_priv->forw_bat_list_lock);

                /* if we could not aggregate this packet with one of the others
                 * we hold it back for a while, so that it might be aggregated
                 * later on
                 */
                if (!own_packet && atomic_read(&bat_priv->aggregated_ogms))
                        send_time += max_aggregation_jiffies;

                batadv_iv_ogm_aggregate_new(packet_buff, packet_len,
                                            send_time, direct_link,
                                            if_incoming, own_packet);
        } else {
                batadv_iv_ogm_aggregate(forw_packet_aggr, packet_buff,
                                        packet_len, direct_link);
                spin_unlock_bh(&bat_priv->forw_bat_list_lock);
        }
}

static void batadv_iv_ogm_forward(struct batadv_orig_node *orig_node,
                                  const struct ethhdr *ethhdr,
                                  struct batadv_ogm_packet *batadv_ogm_packet,
                                  bool is_single_hop_neigh,
                                  bool is_from_best_next_hop,
                                  struct batadv_hard_iface *if_incoming)
{
        struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
        uint8_t tt_num_changes;

        if (batadv_ogm_packet->header.ttl <= 1) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv, "ttl exceeded\n");
                return;
        }

        if (!is_from_best_next_hop) {
                /* Mark the forwarded packet when it is not coming from our
                 * best next hop. We still need to forward the packet for our
                 * neighbor link quality detection to work in case the packet
                 * originated from a single hop neighbor. Otherwise we can
                 * simply drop the ogm.
                 */
                if (is_single_hop_neigh)
                        batadv_ogm_packet->flags |= BATADV_NOT_BEST_NEXT_HOP;
                else
                        return;
        }

        tt_num_changes = batadv_ogm_packet->tt_num_changes;

        batadv_ogm_packet->header.ttl--;
        memcpy(batadv_ogm_packet->prev_sender, ethhdr->h_source, ETH_ALEN);

        /* apply hop penalty */
        batadv_ogm_packet->tq = batadv_hop_penalty(batadv_ogm_packet->tq,
                                                   bat_priv);

        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                   "Forwarding packet: tq: %i, ttl: %i\n",
                   batadv_ogm_packet->tq, batadv_ogm_packet->header.ttl);

        /* switch of primaries first hop flag when forwarding */
        batadv_ogm_packet->flags &= ~BATADV_PRIMARIES_FIRST_HOP;
        if (is_single_hop_neigh)
                batadv_ogm_packet->flags |= BATADV_DIRECTLINK;
        else
                batadv_ogm_packet->flags &= ~BATADV_DIRECTLINK;

        batadv_iv_ogm_queue_add(bat_priv, (unsigned char *)batadv_ogm_packet,
                                BATADV_OGM_HLEN + batadv_tt_len(tt_num_changes),
                                if_incoming, 0, batadv_iv_ogm_fwd_send_time());
}

/**
 * batadv_iv_ogm_slide_own_bcast_window - bitshift own OGM broadcast windows for
 * the given interface
 * @hard_iface: the interface for which the windows have to be shifted
 */
static void
batadv_iv_ogm_slide_own_bcast_window(struct batadv_hard_iface *hard_iface)
{
        struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
        struct batadv_hashtable *hash = bat_priv->orig_hash;
        struct hlist_head *head;
        struct batadv_orig_node *orig_node;
        unsigned long *word;
        uint32_t i;
        size_t word_index;
        uint8_t *w;

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

                rcu_read_lock();
                hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
                        spin_lock_bh(&orig_node->ogm_cnt_lock);
                        word_index = hard_iface->if_num * BATADV_NUM_WORDS;
                        word = &(orig_node->bcast_own[word_index]);

                        batadv_bit_get_packet(bat_priv, word, 1, 0);
                        w = &orig_node->bcast_own_sum[hard_iface->if_num];
                        *w = bitmap_weight(word, BATADV_TQ_LOCAL_WINDOW_SIZE);
                        spin_unlock_bh(&orig_node->ogm_cnt_lock);
                }
                rcu_read_unlock();
        }
}

static void batadv_iv_ogm_schedule(struct batadv_hard_iface *hard_iface)
{
        struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
        unsigned char **ogm_buff = &hard_iface->bat_iv.ogm_buff;
        struct batadv_ogm_packet *batadv_ogm_packet;
        struct batadv_hard_iface *primary_if;
        int *ogm_buff_len = &hard_iface->bat_iv.ogm_buff_len;
        int vis_server, tt_num_changes = 0;
        uint32_t seqno;
        uint8_t bandwidth;

        vis_server = atomic_read(&bat_priv->vis_mode);
        primary_if = batadv_primary_if_get_selected(bat_priv);

        if (hard_iface == primary_if)
                tt_num_changes = batadv_tt_append_diff(bat_priv, ogm_buff,
                                                       ogm_buff_len,
                                                       BATADV_OGM_HLEN);

        batadv_ogm_packet = (struct batadv_ogm_packet *)(*ogm_buff);

        /* change sequence number to network order */
        seqno = (uint32_t)atomic_read(&hard_iface->bat_iv.ogm_seqno);
        batadv_ogm_packet->seqno = htonl(seqno);
        atomic_inc(&hard_iface->bat_iv.ogm_seqno);

        batadv_ogm_packet->ttvn = atomic_read(&bat_priv->tt.vn);
        batadv_ogm_packet->tt_crc = htons(bat_priv->tt.local_crc);
        if (tt_num_changes >= 0)
                batadv_ogm_packet->tt_num_changes = tt_num_changes;

        if (vis_server == BATADV_VIS_TYPE_SERVER_SYNC)
                batadv_ogm_packet->flags |= BATADV_VIS_SERVER;
        else
                batadv_ogm_packet->flags &= ~BATADV_VIS_SERVER;

        if (hard_iface == primary_if &&
            atomic_read(&bat_priv->gw_mode) == BATADV_GW_MODE_SERVER) {
                bandwidth = (uint8_t)atomic_read(&bat_priv->gw_bandwidth);
                batadv_ogm_packet->gw_flags = bandwidth;
        } else {
                batadv_ogm_packet->gw_flags = BATADV_NO_FLAGS;
        }

        batadv_iv_ogm_slide_own_bcast_window(hard_iface);
        batadv_iv_ogm_queue_add(bat_priv, hard_iface->bat_iv.ogm_buff,
                                hard_iface->bat_iv.ogm_buff_len, hard_iface, 1,
                                batadv_iv_ogm_emit_send_time(bat_priv));

        if (primary_if)
                batadv_hardif_free_ref(primary_if);
}

static void
batadv_iv_ogm_orig_update(struct batadv_priv *bat_priv,
                          struct batadv_orig_node *orig_node,
                          const struct ethhdr *ethhdr,
                          const struct batadv_ogm_packet *batadv_ogm_packet,
                          struct batadv_hard_iface *if_incoming,
                          const unsigned char *tt_buff,
                          enum batadv_dup_status dup_status)
{
        struct batadv_neigh_node *neigh_node = NULL, *tmp_neigh_node = NULL;
        struct batadv_neigh_node *router = NULL;
        struct batadv_orig_node *orig_node_tmp;
        int if_num;
        uint8_t sum_orig, sum_neigh;
        uint8_t *neigh_addr;
        uint8_t tq_avg;

        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                   "update_originator(): Searching and updating originator entry of received packet\n");

        rcu_read_lock();
        hlist_for_each_entry_rcu(tmp_neigh_node,
                                 &orig_node->neigh_list, list) {
                neigh_addr = tmp_neigh_node->addr;
                if (batadv_compare_eth(neigh_addr, ethhdr->h_source) &&
                    tmp_neigh_node->if_incoming == if_incoming &&
                    atomic_inc_not_zero(&tmp_neigh_node->refcount)) {
                        if (WARN(neigh_node, "too many matching neigh_nodes"))
                                batadv_neigh_node_free_ref(neigh_node);
                        neigh_node = tmp_neigh_node;
                        continue;
                }

                if (dup_status != BATADV_NO_DUP)
                        continue;

                spin_lock_bh(&tmp_neigh_node->lq_update_lock);
                batadv_ring_buffer_set(tmp_neigh_node->tq_recv,
                                       &tmp_neigh_node->tq_index, 0);
                tq_avg = batadv_ring_buffer_avg(tmp_neigh_node->tq_recv);
                tmp_neigh_node->tq_avg = tq_avg;
                spin_unlock_bh(&tmp_neigh_node->lq_update_lock);
        }

        if (!neigh_node) {
                struct batadv_orig_node *orig_tmp;

                orig_tmp = batadv_get_orig_node(bat_priv, ethhdr->h_source);
                if (!orig_tmp)
                        goto unlock;

                neigh_node = batadv_iv_ogm_neigh_new(if_incoming,
                                                     ethhdr->h_source,
                                                     orig_node, orig_tmp);

                batadv_orig_node_free_ref(orig_tmp);
                if (!neigh_node)
                        goto unlock;
        } else
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Updating existing last-hop neighbor of originator\n");

        rcu_read_unlock();

        orig_node->flags = batadv_ogm_packet->flags;
        neigh_node->last_seen = jiffies;

        spin_lock_bh(&neigh_node->lq_update_lock);
        batadv_ring_buffer_set(neigh_node->tq_recv,
                               &neigh_node->tq_index,
                               batadv_ogm_packet->tq);
        neigh_node->tq_avg = batadv_ring_buffer_avg(neigh_node->tq_recv);
        spin_unlock_bh(&neigh_node->lq_update_lock);

        if (dup_status == BATADV_NO_DUP) {
                orig_node->last_ttl = batadv_ogm_packet->header.ttl;
                neigh_node->last_ttl = batadv_ogm_packet->header.ttl;
        }

        batadv_bonding_candidate_add(orig_node, neigh_node);

        /* if this neighbor already is our next hop there is nothing
         * to change
         */
        router = batadv_orig_node_get_router(orig_node);
        if (router == neigh_node)
                goto update_tt;

        /* if this neighbor does not offer a better TQ we won't consider it */
        if (router && (router->tq_avg > neigh_node->tq_avg))
                goto update_tt;

        /* if the TQ is the same and the link not more symmetric we
         * won't consider it either
         */
        if (router && (neigh_node->tq_avg == router->tq_avg)) {
                orig_node_tmp = router->orig_node;
                spin_lock_bh(&orig_node_tmp->ogm_cnt_lock);
                if_num = router->if_incoming->if_num;
                sum_orig = orig_node_tmp->bcast_own_sum[if_num];
                spin_unlock_bh(&orig_node_tmp->ogm_cnt_lock);

                orig_node_tmp = neigh_node->orig_node;
                spin_lock_bh(&orig_node_tmp->ogm_cnt_lock);
                if_num = neigh_node->if_incoming->if_num;
                sum_neigh = orig_node_tmp->bcast_own_sum[if_num];
                spin_unlock_bh(&orig_node_tmp->ogm_cnt_lock);

                if (sum_orig >= sum_neigh)
                        goto update_tt;
        }

        batadv_update_route(bat_priv, orig_node, neigh_node);

update_tt:
        /* I have to check for transtable changes only if the OGM has been
         * sent through a primary interface
         */
        if (((batadv_ogm_packet->orig != ethhdr->h_source) &&
             (batadv_ogm_packet->header.ttl > 2)) ||
            (batadv_ogm_packet->flags & BATADV_PRIMARIES_FIRST_HOP))
                batadv_tt_update_orig(bat_priv, orig_node, tt_buff,
                                      batadv_ogm_packet->tt_num_changes,
                                      batadv_ogm_packet->ttvn,
                                      ntohs(batadv_ogm_packet->tt_crc));

        if (orig_node->gw_flags != batadv_ogm_packet->gw_flags)
                batadv_gw_node_update(bat_priv, orig_node,
                                      batadv_ogm_packet->gw_flags);

        orig_node->gw_flags = batadv_ogm_packet->gw_flags;

        /* restart gateway selection if fast or late switching was enabled */
        if ((orig_node->gw_flags) &&
            (atomic_read(&bat_priv->gw_mode) == BATADV_GW_MODE_CLIENT) &&
            (atomic_read(&bat_priv->gw_sel_class) > 2))
                batadv_gw_check_election(bat_priv, orig_node);

        goto out;

unlock:
        rcu_read_unlock();
out:
        if (neigh_node)
                batadv_neigh_node_free_ref(neigh_node);
        if (router)
                batadv_neigh_node_free_ref(router);
}

static int batadv_iv_ogm_calc_tq(struct batadv_orig_node *orig_node,
                                 struct batadv_orig_node *orig_neigh_node,
                                 struct batadv_ogm_packet *batadv_ogm_packet,
                                 struct batadv_hard_iface *if_incoming)
{
        struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
        struct batadv_neigh_node *neigh_node = NULL, *tmp_neigh_node;
        uint8_t total_count;
        uint8_t orig_eq_count, neigh_rq_count, neigh_rq_inv, tq_own;
        unsigned int neigh_rq_inv_cube, neigh_rq_max_cube;
        int tq_asym_penalty, inv_asym_penalty, ret = 0;
        unsigned int combined_tq;

        /* find corresponding one hop neighbor */
        rcu_read_lock();
        hlist_for_each_entry_rcu(tmp_neigh_node,
                                 &orig_neigh_node->neigh_list, list) {
                if (!batadv_compare_eth(tmp_neigh_node->addr,
                                        orig_neigh_node->orig))
                        continue;

                if (tmp_neigh_node->if_incoming != if_incoming)
                        continue;

                if (!atomic_inc_not_zero(&tmp_neigh_node->refcount))
                        continue;

                neigh_node = tmp_neigh_node;
                break;
        }
        rcu_read_unlock();

        if (!neigh_node)
                neigh_node = batadv_iv_ogm_neigh_new(if_incoming,
                                                     orig_neigh_node->orig,
                                                     orig_neigh_node,
                                                     orig_neigh_node);

        if (!neigh_node)
                goto out;

        /* if orig_node is direct neighbor update neigh_node last_seen */
        if (orig_node == orig_neigh_node)
                neigh_node->last_seen = jiffies;

        orig_node->last_seen = jiffies;

        /* find packet count of corresponding one hop neighbor */
        spin_lock_bh(&orig_node->ogm_cnt_lock);
        orig_eq_count = orig_neigh_node->bcast_own_sum[if_incoming->if_num];
        neigh_rq_count = neigh_node->real_packet_count;
        spin_unlock_bh(&orig_node->ogm_cnt_lock);

        /* pay attention to not get a value bigger than 100 % */
        if (orig_eq_count > neigh_rq_count)
                total_count = neigh_rq_count;
        else
                total_count = orig_eq_count;

        /* if we have too few packets (too less data) we set tq_own to zero
         * if we receive too few packets it is not considered bidirectional
         */
        if (total_count < BATADV_TQ_LOCAL_BIDRECT_SEND_MINIMUM ||
            neigh_rq_count < BATADV_TQ_LOCAL_BIDRECT_RECV_MINIMUM)
                tq_own = 0;
        else
                /* neigh_node->real_packet_count is never zero as we
                 * only purge old information when getting new
                 * information
                 */
                tq_own = (BATADV_TQ_MAX_VALUE * total_count) /  neigh_rq_count;

        /* 1 - ((1-x) ** 3), normalized to TQ_MAX_VALUE this does
         * affect the nearly-symmetric links only a little, but
         * punishes asymmetric links more.  This will give a value
         * between 0 and TQ_MAX_VALUE
         */
        neigh_rq_inv = BATADV_TQ_LOCAL_WINDOW_SIZE - neigh_rq_count;
        neigh_rq_inv_cube = neigh_rq_inv * neigh_rq_inv * neigh_rq_inv;
        neigh_rq_max_cube = BATADV_TQ_LOCAL_WINDOW_SIZE *
                            BATADV_TQ_LOCAL_WINDOW_SIZE *
                            BATADV_TQ_LOCAL_WINDOW_SIZE;
        inv_asym_penalty = BATADV_TQ_MAX_VALUE * neigh_rq_inv_cube;
        inv_asym_penalty /= neigh_rq_max_cube;
        tq_asym_penalty = BATADV_TQ_MAX_VALUE - inv_asym_penalty;

        combined_tq = batadv_ogm_packet->tq * tq_own * tq_asym_penalty;
        combined_tq /= BATADV_TQ_MAX_VALUE * BATADV_TQ_MAX_VALUE;
        batadv_ogm_packet->tq = combined_tq;

        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                   "bidirectional: orig = %-15pM neigh = %-15pM => own_bcast = %2i, real recv = %2i, local tq: %3i, asym_penalty: %3i, total tq: %3i\n",
                   orig_node->orig, orig_neigh_node->orig, total_count,
                   neigh_rq_count, tq_own,
                   tq_asym_penalty, batadv_ogm_packet->tq);

        /* if link has the minimum required transmission quality
         * consider it bidirectional
         */
        if (batadv_ogm_packet->tq >= BATADV_TQ_TOTAL_BIDRECT_LIMIT)
                ret = 1;

out:
        if (neigh_node)
                batadv_neigh_node_free_ref(neigh_node);
        return ret;
}

/**
 * batadv_iv_ogm_update_seqnos -  process a batman packet for all interfaces,
 *  adjust the sequence number and find out whether it is a duplicate
 * @ethhdr: ethernet header of the packet
 * @batadv_ogm_packet: OGM packet to be considered
 * @if_incoming: interface on which the OGM packet was received
 *
 * Returns duplicate status as enum batadv_dup_status
 */
static enum batadv_dup_status
batadv_iv_ogm_update_seqnos(const struct ethhdr *ethhdr,
                            const struct batadv_ogm_packet *batadv_ogm_packet,
                            const struct batadv_hard_iface *if_incoming)
{
        struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
        struct batadv_orig_node *orig_node;
        struct batadv_neigh_node *tmp_neigh_node;
        int is_dup;
        int32_t seq_diff;
        int need_update = 0;
        int set_mark;
        enum batadv_dup_status ret = BATADV_NO_DUP;
        uint32_t seqno = ntohl(batadv_ogm_packet->seqno);
        uint8_t *neigh_addr;
        uint8_t packet_count;

        orig_node = batadv_get_orig_node(bat_priv, batadv_ogm_packet->orig);
        if (!orig_node)
                return BATADV_NO_DUP;

        spin_lock_bh(&orig_node->ogm_cnt_lock);
        seq_diff = seqno - orig_node->last_real_seqno;

        /* signalize caller that the packet is to be dropped. */
        if (!hlist_empty(&orig_node->neigh_list) &&
            batadv_window_protected(bat_priv, seq_diff,
                                    &orig_node->batman_seqno_reset)) {
                ret = BATADV_PROTECTED;
                goto out;
        }

        rcu_read_lock();
        hlist_for_each_entry_rcu(tmp_neigh_node,
                                 &orig_node->neigh_list, list) {
                neigh_addr = tmp_neigh_node->addr;
                is_dup = batadv_test_bit(tmp_neigh_node->real_bits,
                                         orig_node->last_real_seqno,
                                         seqno);

                if (batadv_compare_eth(neigh_addr, ethhdr->h_source) &&
                    tmp_neigh_node->if_incoming == if_incoming) {
                        set_mark = 1;
                        if (is_dup)
                                ret = BATADV_NEIGH_DUP;
                } else {
                        set_mark = 0;
                        if (is_dup && (ret != BATADV_NEIGH_DUP))
                                ret = BATADV_ORIG_DUP;
                }

                /* if the window moved, set the update flag. */
                need_update |= batadv_bit_get_packet(bat_priv,
                                                     tmp_neigh_node->real_bits,
                                                     seq_diff, set_mark);

                packet_count = bitmap_weight(tmp_neigh_node->real_bits,
                                             BATADV_TQ_LOCAL_WINDOW_SIZE);
                tmp_neigh_node->real_packet_count = packet_count;
        }
        rcu_read_unlock();

        if (need_update) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "updating last_seqno: old %u, new %u\n",
                           orig_node->last_real_seqno, seqno);
                orig_node->last_real_seqno = seqno;
        }

out:
        spin_unlock_bh(&orig_node->ogm_cnt_lock);
        batadv_orig_node_free_ref(orig_node);
        return ret;
}

static void batadv_iv_ogm_process(const struct ethhdr *ethhdr,
                                  struct batadv_ogm_packet *batadv_ogm_packet,
                                  const unsigned char *tt_buff,
                                  struct batadv_hard_iface *if_incoming)
{
        struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
        struct batadv_hard_iface *hard_iface;
        struct batadv_orig_node *orig_neigh_node, *orig_node;
        struct batadv_neigh_node *router = NULL, *router_router = NULL;
        struct batadv_neigh_node *orig_neigh_router = NULL;
        int has_directlink_flag;
        int is_my_addr = 0, is_my_orig = 0, is_my_oldorig = 0;
        int is_bidirect;
        bool is_single_hop_neigh = false;
        bool is_from_best_next_hop = false;
        int sameseq, similar_ttl;
        enum batadv_dup_status dup_status;
        uint32_t if_incoming_seqno;
        uint8_t *prev_sender;

        /* Silently drop when the batman packet is actually not a
         * correct packet.
         *
         * This might happen if a packet is padded (e.g. Ethernet has a
         * minimum frame length of 64 byte) and the aggregation interprets
         * it as an additional length.
         *
         * TODO: A more sane solution would be to have a bit in the
         * batadv_ogm_packet to detect whether the packet is the last
         * packet in an aggregation.  Here we expect that the padding
         * is always zero (or not 0x01)
         */
        if (batadv_ogm_packet->header.packet_type != BATADV_IV_OGM)
                return;

        /* could be changed by schedule_own_packet() */
        if_incoming_seqno = atomic_read(&if_incoming->bat_iv.ogm_seqno);

        if (batadv_ogm_packet->flags & BATADV_DIRECTLINK)
                has_directlink_flag = 1;
        else
                has_directlink_flag = 0;

        if (batadv_compare_eth(ethhdr->h_source, batadv_ogm_packet->orig))
                is_single_hop_neigh = true;

        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                   "Received BATMAN packet via NB: %pM, IF: %s [%pM] (from OG: %pM, via prev OG: %pM, seqno %u, ttvn %u, crc %#.4x, changes %u, tq %d, TTL %d, V %d, IDF %d)\n",
                   ethhdr->h_source, if_incoming->net_dev->name,
                   if_incoming->net_dev->dev_addr, batadv_ogm_packet->orig,
                   batadv_ogm_packet->prev_sender,
                   ntohl(batadv_ogm_packet->seqno), batadv_ogm_packet->ttvn,
                   ntohs(batadv_ogm_packet->tt_crc),
                   batadv_ogm_packet->tt_num_changes, batadv_ogm_packet->tq,
                   batadv_ogm_packet->header.ttl,
                   batadv_ogm_packet->header.version, has_directlink_flag);

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

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

                if (batadv_compare_eth(ethhdr->h_source,
                                       hard_iface->net_dev->dev_addr))
                        is_my_addr = 1;

                if (batadv_compare_eth(batadv_ogm_packet->orig,
                                       hard_iface->net_dev->dev_addr))
                        is_my_orig = 1;

                if (batadv_compare_eth(batadv_ogm_packet->prev_sender,
                                       hard_iface->net_dev->dev_addr))
                        is_my_oldorig = 1;
        }
        rcu_read_unlock();

        if (is_my_addr) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: received my own broadcast (sender: %pM)\n",
                           ethhdr->h_source);
                return;
        }

        if (is_my_orig) {
                unsigned long *word;
                int offset;
                int32_t bit_pos;
                int16_t if_num;
                uint8_t *weight;

                orig_neigh_node = batadv_get_orig_node(bat_priv,
                                                       ethhdr->h_source);
                if (!orig_neigh_node)
                        return;

                /* neighbor has to indicate direct link and it has to
                 * come via the corresponding interface
                 * save packet seqno for bidirectional check
                 */
                if (has_directlink_flag &&
                    batadv_compare_eth(if_incoming->net_dev->dev_addr,
                                       batadv_ogm_packet->orig)) {
                        if_num = if_incoming->if_num;
                        offset = if_num * BATADV_NUM_WORDS;

                        spin_lock_bh(&orig_neigh_node->ogm_cnt_lock);
                        word = &(orig_neigh_node->bcast_own[offset]);
                        bit_pos = if_incoming_seqno - 2;
                        bit_pos -= ntohl(batadv_ogm_packet->seqno);
                        batadv_set_bit(word, bit_pos);
                        weight = &orig_neigh_node->bcast_own_sum[if_num];
                        *weight = bitmap_weight(word,
                                                BATADV_TQ_LOCAL_WINDOW_SIZE);
                        spin_unlock_bh(&orig_neigh_node->ogm_cnt_lock);
                }

                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: originator packet from myself (via neighbor)\n");
                batadv_orig_node_free_ref(orig_neigh_node);
                return;
        }

        if (is_my_oldorig) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: ignoring all rebroadcast echos (sender: %pM)\n",
                           ethhdr->h_source);
                return;
        }

        if (batadv_ogm_packet->flags & BATADV_NOT_BEST_NEXT_HOP) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: ignoring all packets not forwarded from the best next hop (sender: %pM)\n",
                           ethhdr->h_source);
                return;
        }

        orig_node = batadv_get_orig_node(bat_priv, batadv_ogm_packet->orig);
        if (!orig_node)
                return;

        dup_status = batadv_iv_ogm_update_seqnos(ethhdr, batadv_ogm_packet,
                                                 if_incoming);

        if (dup_status == BATADV_PROTECTED) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: packet within seqno protection time (sender: %pM)\n",
                           ethhdr->h_source);
                goto out;
        }

        if (batadv_ogm_packet->tq == 0) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: originator packet with tq equal 0\n");
                goto out;
        }

        router = batadv_orig_node_get_router(orig_node);
        if (router)
                router_router = batadv_orig_node_get_router(router->orig_node);

        if ((router && router->tq_avg != 0) &&
            (batadv_compare_eth(router->addr, ethhdr->h_source)))
                is_from_best_next_hop = true;

        prev_sender = batadv_ogm_packet->prev_sender;
        /* avoid temporary routing loops */
        if (router && router_router &&
            (batadv_compare_eth(router->addr, prev_sender)) &&
            !(batadv_compare_eth(batadv_ogm_packet->orig, prev_sender)) &&
            (batadv_compare_eth(router->addr, router_router->addr))) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: ignoring all rebroadcast packets that may make me loop (sender: %pM)\n",
                           ethhdr->h_source);
                goto out;
        }

        /* if sender is a direct neighbor the sender mac equals
         * originator mac
         */
        if (is_single_hop_neigh)
                orig_neigh_node = orig_node;
        else
                orig_neigh_node = batadv_get_orig_node(bat_priv,
                                                       ethhdr->h_source);

        if (!orig_neigh_node)
                goto out;

        /* Update nc_nodes of the originator */
        batadv_nc_update_nc_node(bat_priv, orig_node, orig_neigh_node,
                                 batadv_ogm_packet, is_single_hop_neigh);

        orig_neigh_router = batadv_orig_node_get_router(orig_neigh_node);

        /* drop packet if sender is not a direct neighbor and if we
         * don't route towards it
         */
        if (!is_single_hop_neigh && (!orig_neigh_router)) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: OGM via unknown neighbor!\n");
                goto out_neigh;
        }

        is_bidirect = batadv_iv_ogm_calc_tq(orig_node, orig_neigh_node,
                                            batadv_ogm_packet, if_incoming);

        batadv_bonding_save_primary(orig_node, orig_neigh_node,
                                    batadv_ogm_packet);

        /* update ranking if it is not a duplicate or has the same
         * seqno and similar ttl as the non-duplicate
         */
        sameseq = orig_node->last_real_seqno == ntohl(batadv_ogm_packet->seqno);
        similar_ttl = orig_node->last_ttl - 3 <= batadv_ogm_packet->header.ttl;
        if (is_bidirect && ((dup_status == BATADV_NO_DUP) ||
                            (sameseq && similar_ttl)))
                batadv_iv_ogm_orig_update(bat_priv, orig_node, ethhdr,
                                          batadv_ogm_packet, if_incoming,
                                          tt_buff, dup_status);

        /* is single hop (direct) neighbor */
        if (is_single_hop_neigh) {
                /* mark direct link on incoming interface */
                batadv_iv_ogm_forward(orig_node, ethhdr, batadv_ogm_packet,
                                      is_single_hop_neigh,
                                      is_from_best_next_hop, if_incoming);

                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Forwarding packet: rebroadcast neighbor packet with direct link flag\n");
                goto out_neigh;
        }

        /* multihop originator */
        if (!is_bidirect) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: not received via bidirectional link\n");
                goto out_neigh;
        }

        if (dup_status == BATADV_NEIGH_DUP) {
                batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                           "Drop packet: duplicate packet received\n");
                goto out_neigh;
        }

        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
                   "Forwarding packet: rebroadcast originator packet\n");
        batadv_iv_ogm_forward(orig_node, ethhdr, batadv_ogm_packet,
                              is_single_hop_neigh, is_from_best_next_hop,
                              if_incoming);

out_neigh:
        if ((orig_neigh_node) && (!is_single_hop_neigh))
                batadv_orig_node_free_ref(orig_neigh_node);
out:
        if (router)
                batadv_neigh_node_free_ref(router);
        if (router_router)
                batadv_neigh_node_free_ref(router_router);
        if (orig_neigh_router)
                batadv_neigh_node_free_ref(orig_neigh_router);

        batadv_orig_node_free_ref(orig_node);
}

static int batadv_iv_ogm_receive(struct sk_buff *skb,
                                 struct batadv_hard_iface *if_incoming)
{
        struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
        struct batadv_ogm_packet *batadv_ogm_packet;
        struct ethhdr *ethhdr;
        int buff_pos = 0, packet_len;
        unsigned char *tt_buff, *packet_buff;
        bool ret;
        uint8_t *packet_pos;

        ret = batadv_check_management_packet(skb, if_incoming, BATADV_OGM_HLEN);
        if (!ret)
                return NET_RX_DROP;

        /* did we receive a B.A.T.M.A.N. IV OGM packet on an interface
         * that does not have B.A.T.M.A.N. IV enabled ?
         */
        if (bat_priv->bat_algo_ops->bat_ogm_emit != batadv_iv_ogm_emit)
                return NET_RX_DROP;

        batadv_inc_counter(bat_priv, BATADV_CNT_MGMT_RX);
        batadv_add_counter(bat_priv, BATADV_CNT_MGMT_RX_BYTES,
                           skb->len + ETH_HLEN);

        packet_len = skb_headlen(skb);
        ethhdr = eth_hdr(skb);
        packet_buff = skb->data;
        batadv_ogm_packet = (struct batadv_ogm_packet *)packet_buff;

        /* unpack the aggregated packets and process them one by one */
        while (batadv_iv_ogm_aggr_packet(buff_pos, packet_len,
                                         batadv_ogm_packet->tt_num_changes)) {
                tt_buff = packet_buff + buff_pos + BATADV_OGM_HLEN;

                batadv_iv_ogm_process(ethhdr, batadv_ogm_packet, tt_buff,
                                      if_incoming);

                buff_pos += BATADV_OGM_HLEN;
                buff_pos += batadv_tt_len(batadv_ogm_packet->tt_num_changes);

                packet_pos = packet_buff + buff_pos;
                batadv_ogm_packet = (struct batadv_ogm_packet *)packet_pos;
        }

        kfree_skb(skb);
        return NET_RX_SUCCESS;
}

static struct batadv_algo_ops batadv_batman_iv __read_mostly = {
        .name = "BATMAN_IV",
        .bat_iface_enable = batadv_iv_ogm_iface_enable,
        .bat_iface_disable = batadv_iv_ogm_iface_disable,
        .bat_iface_update_mac = batadv_iv_ogm_iface_update_mac,
        .bat_primary_iface_set = batadv_iv_ogm_primary_iface_set,
        .bat_ogm_schedule = batadv_iv_ogm_schedule,
        .bat_ogm_emit = batadv_iv_ogm_emit,
};

int __init batadv_iv_init(void)
{
        int ret;

        /* batman originator packet */
        ret = batadv_recv_handler_register(BATADV_IV_OGM,
                                           batadv_iv_ogm_receive);
        if (ret < 0)
                goto out;

        ret = batadv_algo_register(&batadv_batman_iv);
        if (ret < 0)
                goto handler_unregister;

        goto out;

handler_unregister:
        batadv_recv_handler_unregister(BATADV_IV_OGM);
out:
        return ret;
}