[OpenWrt-Devel] [PATCH] netifd: Send DHCP release when client exits

Hans Dedecker dedeckeh at gmail.com
Mon Apr 18 05:01:09 EDT 2016


On Sun, Apr 17, 2016 at 2:07 PM, Hauke Mehrtens <hauke at hauke-m.de> wrote:

> On 03/31/2016 12:18 PM, Hans Dedecker wrote:
> > Let DHCP client send a release when it exists so the DHCP server is
> > informed the IP address is released and allowing to clean up IP/mac
> > state info in intermediate devices.
> >
> > Signed-off-by: Hans Dedecker <dedeckeh at gmail.com>
>
> I think in the normal case we should not send a release, so we can get
> the IP address back later.
>
> https://www.ietf.org/rfc/rfc2131.txt says in section 3.2 part 4.:
>       Note that in this case, where the client retains its network
>       address locally, the client will not normally relinquish its
>       lease during a graceful shutdown.  Only in the case where the
>       client explicitly needs to relinquish its lease, e.g., the client
>       is about to be moved to a different subnet, will the client send
>       a DHCPRELEASE message.
>
It's a bit ambiguous to interprete (like so many statements in rfc2131 :) )
as we don't keep the IP address locally when the udhcpc client is shutdown.

>
> What about making this configurable?

Fine to make it configurable; will send a follow-up patch in one of the
next days

Hans

>
> Hauke
>
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