[avahi] [PATCH] avahi-autoipd: only consider ARP Probe packets

[Christian Hitz]

Hi,

we noticed that avahi-autoipd selects a new IP when it receives an ARP
request during the probe phase.

According to RFC3927, Section 2.2.1. Probe details:
> An ARP Request constructed this way with an all-zero 'sender IP 
> address' is referred to as an "ARP Probe".

and

> In addition, if during this period [checking if an address is already 
> in use] the host receives any ARP Probe where the packet's 'target IP
> address' is the address being probed for, and the packet's 'sender
> hardware address' is not the hardware address of the interface the
> host is attempting to configure, then the host MUST similarly treat
> this as an address conflict and select a new address as above.

When receiving an ARP packet during probe avahi-autoipd does not check
if the 'sender IP address' is all-zero and therefore if the packet is an
ARP Probe.

The attached patch adds this check.

Regards,
Christian

-- 
Christian Hitz                   digitalSTROM ag, Schlieren, Switzerland
Software Development                         http://www.digitalstrom.com
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