diff options
| -rw-r--r-- | net/batman-adv/multicast_forw.c | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/net/batman-adv/multicast_forw.c b/net/batman-adv/multicast_forw.c index a2c5c587b8fb..fafd6ba8c056 100644 --- a/net/batman-adv/multicast_forw.c +++ b/net/batman-adv/multicast_forw.c @@ -698,6 +698,212 @@ 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 * @skb: the received or locally generated batman-adv multicast packet @@ -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, |