Re: [PATCH] Work around dhclient brokenness

Avi Kivity
2008-08-18T10:56:58Z

Anthony Liguori wrote:
> With the latest GSO/csum offload patches, any guest using an unpatched version
> of dhclient (any Ubuntu guest, for instance), will no longer be able to get
> a DHCP address.
>
> dhclient is actually at fault here. It uses AF_PACKET to receive DHCP responses
> but does not check auxdata to see if the packet has a valid csum. This causes
> it to throw out the DHCP responses it gets from the virtio interface as there
> is not a valid checksum.
>
> Fedora has carried a patch to fix their dhclient (it's needed for Xen too) but
> this patch has not made it into a release of dhclient. AFAIK, the patch is in
> the dhclient CVS but I cannot confirm since their CVS is not public.
>
> This patch, suggested by Rusty, looks for UDP packets (of a normal MTU) and
> explicitly adds a checksum to them if they are missing one. We could further
> refine the search criteria based on srcport but that's probably unnecessary.
>
>

Won't this slow down nfs/udp? I think a srcport check would be good here.

--
error compiling committee.c: too many arguments to function