[avahi] reflector over ipv6

bombela bombela at gmail.com
Tue Dec 21 09:02:14 PST 2010

Hi again,

We join a patch that apparently solve the problem.
In fact the issue was not in the reflector response processing, but in
the reflector query processing.
When a new query is processed through the reflector, the query is
first dispatched trough all the others interfaces, then all the
current cache entry corresponding to this query from all the others
interfaces are sent back, to prevent any answers suppression.

There it was the problem:
All the cache entries associated with an interface can be duplicated
in ipv6, one entry for the local-link only address, and the second for
the network wide address.

Because the reflector answer back ALL the cache entries, without
taking care of the fact that some IPs could be link-local only
addresses, then the link-local only address is published on another

This patch correct the issue by filtering caches entries before sent
them back to the querier.
All ipv6 link-local addresses are simply ignored.

Thanks for reviewing this patch.


On Tue, Dec 21, 2010 at 3:54 PM, Phil Vandry <vandry at tzone.org> wrote:
> On Tue, 21 Dec 2010 14:47:11 +0100 bombela <bombela at gmail.com> wrote:
>>  - Did I should use avahi API in my client (rather than libc
>> getaddrinfo) and filter any name resolution (if that even possible to
>> get every addresses of the host)?
>>  - Did I should (if that even possible) disable link-local addresses
>> support at all in avahi ?
>>  - Did I should patch avahi make reflector to filter link-local addresses?
> I have also noticed this problem, and I believe your LAST proposed
> solution is the best one. Clearly nothing should be done to stop
> link-local addresses from being used on the LAN: DNS-SD is designed to
> be usable on a network with only link-local addresses. It's only their
> reflection that's a problem.
> -Phil

François-Xavier Bourlet
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