ipv4_is_zeronet() checks if the first byte of the address is zero, to my
knowledge there is no special funtion for checking for the unspecified
address, as the case is trivial and independent of byte ordering.

It might make sense though to check for different types of addresses
that are invalid for ARP (zeronet, loopback, multicast, etc.), but I
wanted to keep the patch as simple as possible. If you think these
should be filtered as well, I'll prepare a v2.

Matthias


On 01/23/2013 10:07 PM, Antonio Quartulli wrote:
> On Wed, Jan 23, 2013 at 06:11:54 +0100, Matthias Schiffer wrote:
>> Due to duplicate address detection and other strange ARP packets, sometimes
>> entries with broadcast MAC addresses or unspecified IP addresses would get into
>> the Distributed ARP Table. This patch prevents these and some other kinds of
>> invalid entries from getting into the DAT.
>>
>> Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
>> ---
>>  distributed-arp-table.c | 12 ++++++++++++
>>  1 file changed, 12 insertions(+)
>>
>> diff --git a/distributed-arp-table.c b/distributed-arp-table.c
>> index 9f4cff3..e28be57 100644
>> --- a/distributed-arp-table.c
>> +++ b/distributed-arp-table.c
>> @@ -274,6 +274,18 @@ static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
>>  	struct batadv_dat_entry *dat_entry;
>>  	int hash_added;
>>  
>> +	/* filter invalid MAC addresses that are sometimes used as
>> +	 * destinations of ARP replies
>> +	 */
>> +	if (is_zero_ether_addr(mac_addr) || is_multicast_ether_addr(mac_addr))
>> +		return;
>> +
>> +	/* ARP requests with unspecified source address are used for
>> +	 * duplicate address detection, we don't want those in the DAT either
>> +	 */
>> +	if (!ip)
> 
> Hi Matthias,
> what about using ipv4_is_zeronet() ? Even if this is a base case, I would rather
> prefer to use an already implemented function.
> 
> Cheers,
>