On Fri, Dec 22, 2017 at 03:10:18PM +0100, Lorenzo Bianconi wrote: > Introduce peer_offset parameter in order to add the capability > to specify two different values for payload offset on tx/rx side. > If just offset is provided by userspace use it for rx side as well > in order to maintain compatibility with older l2tp versions > Sorry for being late on this, I originally missed this patchset and only noticed it yesterday.
Lorenzo, can you give some context around this new feature? Quite frankly I can't see the point of it. I've never heard of offsets in L2TPv3, and for L2TPv2, the offset value is already encoded in the header. After a quick review of L2TPv3 and pseudowires RFCs, I still don't see how adding some padding between the L2TPv3 header and the payload could constitute a valid frame. Of course, the base feature is already there, but after a quick test, it looks like the padding bits aren't initialised and leak memory. So, unless I missed something, setting offsets in L2TPv3 is non-compliant, the current implementation is buggy and most likely unused. I'd really prefer getting the implementation fixed, or even removed entirely. Extending it to allow asymmetrical offset values looks wrong to me, unless you have a use case in mind. Regards, Guillaume PS: I also noticed that iproute2 has a "peer_offset" option, but it's a noop.
