Subject: Re: l2tpv3 support not yet in iproute2?

From: James Chapman <[email-masked]>
Date: Mon, 27 Sep 2010 18:26:38 +0100

On 27/09/2010 17:23, Eric Dumazet wrote:
> Le lundi 27 septembre 2010 à 15:22 +0000, jpo234 a écrit :
>> Hello all,
>> some time ago James Chapman sent patches that add L2TPv3 support to iproute2:
>> http://kerneltrap.org/mailarchive/linux-netdev/2010/3/18/6272266/thread
>> While the kernel support arrived in 2.6.35 the user space configuration support
>> still seems to be missing:
>> iproute2-2.6.35$ find . -type f -iname "*.c" | xargs fgrep -i l2tp
>> doesn't find anything.
>>
>> Can somebody clarify the current situation?

Stephen Hemminger (maintainer of iproute2) rejected the patches because
they would add a dependency of libnl to iproute2. iproute2 uses
libnetlink, not libnl. Stephen's objections are reasonable.

The l2tpv3 API uses generic-netlink (genl) which is handled by libnl
APIs very well (and is the main reason why libnl was chosen in the first
place). To recode using libnetlink would require working with low level
libnetlink helpers to build/parse genl messages at low level,
effectively reimplementing some of what is already handled by libnl. I
don't have motivation or time to do this, though I'm happy to support
someone else doing so.

As a quick solution, I posted a new utility, l2tpv3tun, which does the
same as the iproute2 l2tpv3 patches in a standalone utility. l2tpv3tun
is at ftp://ftp.openl2tp.org/releases/l2tpv3tun-0.1.tar.gz

> Hmm, this reminds me l2tp locking is buggy and not yet fixed.
> 
> http://kerneltrap.org/mailarchive/linux-netdev/2010/4/20/6275106
> 
> James, any chance you could fix the locking ?

This dropped off my radar. I'm too busy right now but I'll look at it as
soon as I can, unless someone else beats me to it.

-- 
James Chapman
Katalix Systems Ltd
http://www.katalix.com
Catalysts for your Embedded Linux software development