[Users] Natping in "dispatcher scenario"

[Andreas Granig]

Helge Waastad wrote:
> Does anyone else find it interesting to have the ping also relayed via
> the OBP?
> If not, I just have to move the registrar more towards the frontend.

We ended up in implementing a simple stand-alone natping application for
a proof-of-concept design using raw sockets for spoofing the OBP
address, mainly for two reasons:

- Performance: a possibility would be to evaluate the Path uri in the
registrar and send a sip-based nat-ping (OPTION) with a pre-set route,
but this would really stress the OBP (assume you've to ping 50.000 UACs
every 60 seconds).

- Simplicity: it would require quite a lot of changes in
registrar/usrloc/nathelper/mediaproxy, so we just query the
received-column of usrloc from the external natping application(s) and
send empty udp packets.

Patches to the registrar and a new path module for accomplishing this
(inserting proper Path headers in an OBP, and taking the
received-address from a Path uri parameter and saving it into usrloc in
a registrar) will be contributed the next days...

Bye,
Andy