One possible way of supporting MPLS labels in bird 1.6

[Christian Tacke]

Hi!

On Sat, Aug 12, 2017 at 19:41:54 +0300, Lennert Buytenhek wrote:
[...]
> Notes:
[...]
> * The netlink serialization code in bird 1.6 has a bug whereby if you
>   try to serialize an attribute that is not a multiple of 4 bytes long
>   (such as RTA_ENCAP_TYPE, which is needed for MPLS and has a payload
>   of only 2 bytes) it will round up the size in the netlink header
>   (which is wrong -- that field should reflect the length _without_
>   padding) but then send out a netlink message without the padding
>   appended if this was the last attribute in the message (which is also
>   wrong).  Also, if you do try to serialize an attribute that is not a
>   multiple of 4 bytes long, then between 1 and 3 bytes of uninitialized
>   bird stack memory get leaked over netlink.  (The netlink attributes
>   that upstream bird cares about are all multiples of 4 bytes long, so
>   this won't actually surface in current bird upstream.)
[...]

I don't know much about netlink etc and haven't looked at
the code, but from this summary, it sounds like this should
be fixed/included in bird, to avoid surprises in the
future, when people want to do more interesting stuff with
netlink.

That said: Would it make sense to extract that part and
submit it alone?

Cheers

Christian

-- 
www.cosmokey.com