An entry in DAT with the hashed position of 0 can cause a NULL pointer
dereference when the first entry is checked by batadv_choose_next_candidate.
This first candidate automatically has the max value of 0 and the max_orig_node
of NULL. Not checking max_orig_node for NULL in batadv_is_orig_node_eligible
will lead to a NULL pointer dereference when checking for the lowest address.

This problem was added in 785ea114
("batman-adv: Distributed ARP Table - create DHT helper functions").
Signed-off-by: NPau Koning <paukoning@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We never want multicast MAC addresses in the Distributed ARP Table, so it's
best to completely ignore ARP packets containing them where we expect unicast
addresses.
Signed-off-by: NMatthias Schiffer <mschiffer@universe-factory.net>
Acked-by: NAntonio Quartulli <ordex@autistici.org>
Signed-off-by: NMarek Lindner <lindner_marek@yahoo.de>
Signed-off-by: NAntonio Quartulli <ordex@autistici.org>

There are more types of IP addresses that may appear in ARP packets that we
don't want to process. While some of these should never appear in sane ARP
packets, a 0.0.0.0 source is used for duplicate address detection and thus seen
quite often.
Signed-off-by: NMatthias Schiffer <mschiffer@universe-factory.net>
Acked-by: NAntonio Quartulli <ordex@autistici.org>
Signed-off-by: NMarek Lindner <lindner_marek@yahoo.de>
Signed-off-by: NAntonio Quartulli <ordex@autistici.org>

The callers of batadv_dat_snoop_incoming_arp_reply() assume the skb has been
freed when it returns true; fix this by calling kfree_skb before returning as
it is done in batadv_dat_snoop_incoming_arp_request().
Signed-off-by: NMatthias Schiffer <mschiffer@universe-factory.net>
Signed-off-by: NMarek Lindner <lindner_marek@yahoo.de>
Acked-by: NAntonio Quartulli <ordex@autistici.org>
Signed-off-by: NAntonio Quartulli <ordex@autistici.org>

Added additional counters for D.A.T.
Signed-off-by: NMartin Hundebøll <martin@hundeboll.net>
Signed-off-by: NAntonio Quartulli <ordex@autistici.org>

This patch adds a runtime switch that enables the user to turn the DAT feature
on or off at runtime
Signed-off-by: NAntonio Quartulli <ordex@autistici.org>

In case of an ARP message going in or out the soft_iface, it is intercepted and
a special action is performed. In particular the DHT helper functions previously
implemented are used to store all the ARP entries belonging to the network in
order to provide a fast and unicast lookup instead of the classic broadcast
flooding mechanism.
Each node stores the entries it is responsible for (following the DHT rules) in
its soft_iface ARP table. This makes it possible to reuse the kernel data
structures and functions for ARP management.
Signed-off-by: NAntonio Quartulli <ordex@autistici.org>

ARP messages are now parsed to make it possible to trigger special actions
depending on their types (snooping).
Signed-off-by: NAntonio Quartulli <ordex@autistici.org>

Since batman-adv cannot inter-operate with the host ARP table, this patch
introduces a batman-adv private storage for ARP entries exchanged within DAT.
This storage will represent the node local cache in the DAT protocol.
Signed-off-by: NAntonio Quartulli <ordex@autistici.org>

Add all the relevant functions in order to manage a Distributed Hash Table over
the B.A.T.M.A.N.-adv network. It will later be used to store several ARP entries
and implement DAT (Distributed ARP Table)
Signed-off-by: NAntonio Quartulli <ordex@autistici.org>