@@ -697,6 +697,212 @@ batadv_mcast_forw_scrub_dests(struct batadv_priv *bat_priv,
}
}
+/**
+ * batadv_mcast_forw_shrink_fill() - swap slot with next non-zero destination
+ * @slot: the to be filled zero-MAC destination entry in a tracker TVLV
+ * @num_dests_slot: remaining entries in tracker TVLV from/including slot
+ *
+ * Searches for the next non-zero-MAC destination entry in a tracker TVLV after
+ * the given slot pointer. And if found, swaps it with the zero-MAC destination
+ * entry which the slot points to.
+ *
+ * Return: true if slot was swapped/filled successfully, false otherwise.
+ */
+static bool batadv_mcast_forw_shrink_fill(u8 *slot, u16 num_dests_slot)
+{
+ u16 num_dests_filler;
+ u8 *filler;
+
+ /* sanity check, should not happen */
+ if (!num_dests_slot)
+ return false;
+
+ num_dests_filler = num_dests_slot - 1;
+ filler = slot + ETH_ALEN;
+
+ /* find a candidate to fill the empty slot */
+ batadv_mcast_forw_tracker_for_each_dest(filler, num_dests_filler) {
+ if (is_zero_ether_addr(filler))
+ continue;
+
+ ether_addr_copy(slot, filler);
+ eth_zero_addr(filler);
+ return true;
+ }
+
+ return false;
+}
+
+/**
+ * batadv_mcast_forw_shrink_pack_dests() - pack destinations of a tracker TVLV
+ * @skb: the batman-adv multicast packet to compact destinations in
+ *
+ * Compacts the originator destination MAC addresses in the multicast tracker
+ * TVLV of the given multicast packet. This is done by moving all non-zero
+ * MAC addresses in direction of the skb head and all zero MAC addresses in skb
+ * tail direction, within the multicast tracker TVLV.
+ *
+ * Return: The number of consecutive zero MAC address destinations which are
+ * now at the end of the multicast tracker TVLV.
+ */
+static int batadv_mcast_forw_shrink_pack_dests(struct sk_buff *skb)
+{
+ struct batadv_tvlv_mcast_tracker *mcast_tracker;
+ unsigned char *skb_net_hdr;
+ u16 num_dests_slot;
+ u8 *slot;
+
+ skb_net_hdr = skb_network_header(skb);
+ mcast_tracker = (struct batadv_tvlv_mcast_tracker *)skb_net_hdr;
+ num_dests_slot = ntohs(mcast_tracker->num_dests);
+
+ slot = (u8 *)mcast_tracker + sizeof(*mcast_tracker);
+
+ batadv_mcast_forw_tracker_for_each_dest(slot, num_dests_slot) {
+ /* find an empty slot */
+ if (!is_zero_ether_addr(slot))
+ continue;
+
+ if (!batadv_mcast_forw_shrink_fill(slot, num_dests_slot))
+ /* could not find a filler, so we successfully packed
+ * and can stop - and must not reduce num_dests_slot!
+ */
+ break;
+ }
+
+ /* num_dests_slot is now the amount of reduced, zeroed
+ * destinations at the end of the tracker TVLV
+ */
+ return num_dests_slot;
+}
+
+/**
+ * batadv_mcast_forw_shrink_align_offset() - get new alignment offset
+ * @num_dests_old: the old, to be updated amount of destination nodes
+ * @num_dests_reduce: the number of destinations that were removed
+ *
+ * Calculates the amount of potential extra alignment offset that is needed to
+ * adjust the TVLV padding after the change in destination nodes.
+ *
+ * Return:
+ * 0: If no change to padding is needed.
+ * 2: If padding needs to be removed.
+ * -2: If padding needs to be added.
+ */
+static short
+batadv_mcast_forw_shrink_align_offset(unsigned int num_dests_old,
+ unsigned int num_dests_reduce)
+{
+ /* even amount of removed destinations -> no alignment change */
+ if (!(num_dests_reduce % 2))
+ return 0;
+
+ /* even to odd amount of destinations -> remove padding */
+ if (!(num_dests_old % 2))
+ return 2;
+
+ /* odd to even amount of destinations -> add padding */
+ return -2;
+}
+
+/**
+ * batadv_mcast_forw_shrink_update_headers() - update shrunk mc packet headers
+ * @skb: the batman-adv multicast packet to update headers of
+ * @num_dests_reduce: the number of destinations that were removed
+ *
+ * This updates any fields of a batman-adv multicast packet that are affected
+ * by the reduced number of destinations in the multicast tracket TVLV. In
+ * particular this updates:
+ *
+ * The num_dest field of the multicast tracker TVLV.
+ * The TVLV length field of the according generic TVLV header.
+ * The batman-adv multicast packet's total TVLV length field.
+ *
+ * Return: The offset in skb's tail direction at which the new batman-adv
+ * multicast packet header needs to start.
+ */
+static unsigned int
+batadv_mcast_forw_shrink_update_headers(struct sk_buff *skb,
+ unsigned int num_dests_reduce)
+{
+ struct batadv_tvlv_mcast_tracker *mcast_tracker;
+ struct batadv_mcast_packet *mcast_packet;
+ struct batadv_tvlv_hdr *tvlv_hdr;
+ unsigned char *skb_net_hdr;
+ unsigned int offset;
+ short align_offset;
+ u16 num_dests;
+
+ skb_net_hdr = skb_network_header(skb);
+ mcast_tracker = (struct batadv_tvlv_mcast_tracker *)skb_net_hdr;
+ num_dests = ntohs(mcast_tracker->num_dests);
+
+ align_offset = batadv_mcast_forw_shrink_align_offset(num_dests,
+ num_dests_reduce);
+ offset = ETH_ALEN * num_dests_reduce + align_offset;
+ num_dests -= num_dests_reduce;
+
+ /* update tracker header */
+ mcast_tracker->num_dests = htons(num_dests);
+
+ /* update tracker's tvlv header's length field */
+ tvlv_hdr = (struct batadv_tvlv_hdr *)(skb_network_header(skb) -
+ sizeof(*tvlv_hdr));
+ tvlv_hdr->len = htons(ntohs(tvlv_hdr->len) - offset);
+
+ /* update multicast packet header's tvlv length field */
+ mcast_packet = (struct batadv_mcast_packet *)skb->data;
+ mcast_packet->tvlv_len = htons(ntohs(mcast_packet->tvlv_len) - offset);
+
+ return offset;
+}
+
+/**
+ * batadv_mcast_forw_shrink_move_headers() - move multicast headers by offset
+ * @skb: the batman-adv multicast packet to move headers for
+ * @offset: a non-negative offset to move headers by, towards the skb tail
+ *
+ * Moves the batman-adv multicast packet header, its multicast tracker TVLV and
+ * any TVLVs in between by the given offset in direction towards the tail.
+ */
+static void
+batadv_mcast_forw_shrink_move_headers(struct sk_buff *skb, unsigned int offset)
+{
+ struct batadv_tvlv_mcast_tracker *mcast_tracker;
+ unsigned char *skb_net_hdr;
+ unsigned int len;
+ u16 num_dests;
+
+ skb_net_hdr = skb_network_header(skb);
+ mcast_tracker = (struct batadv_tvlv_mcast_tracker *)skb_net_hdr;
+ num_dests = ntohs(mcast_tracker->num_dests);
+ len = skb_network_offset(skb) + sizeof(*mcast_tracker);
+ len += num_dests * ETH_ALEN;
+
+ batadv_mcast_forw_scrape(skb, len, offset);
+}
+
+/**
+ * batadv_mcast_forw_shrink_tracker() - remove zero addresses in a tracker tvlv
+ * @skb: the batman-adv multicast packet to (potentially) shrink
+ *
+ * Removes all destinations with a zero MAC addresses (00:00:00:00:00:00) from
+ * the given batman-adv multicast packet's tracker TVLV and updates headers
+ * accordingly to maintain a valid batman-adv multicast packet.
+ */
+static void batadv_mcast_forw_shrink_tracker(struct sk_buff *skb)
+{
+ unsigned int offset;
+ u16 dests_reduced;
+
+ dests_reduced = batadv_mcast_forw_shrink_pack_dests(skb);
+ if (!dests_reduced)
+ return;
+
+ offset = batadv_mcast_forw_shrink_update_headers(skb, dests_reduced);
+ batadv_mcast_forw_shrink_move_headers(skb, offset);
+}
+
/**
* batadv_mcast_forw_packet() - forward a batman-adv multicast packet
* @bat_priv: the bat priv with all the soft interface information
@@ -786,6 +992,7 @@ static int batadv_mcast_forw_packet(struct batadv_priv *bat_priv,
batadv_mcast_forw_scrub_dests(bat_priv, neigh_node, dest,
next_dest, num_dests);
+ batadv_mcast_forw_shrink_tracker(nexthop_skb);
batadv_inc_counter(bat_priv, BATADV_CNT_MCAST_TX);
batadv_add_counter(bat_priv, BATADV_CNT_MCAST_TX_BYTES,