[SR-Users] Kamailio propagates 180 and 200 OK OUT OF ORDER

[Alex Balashov]

On Wed, Apr 15, 2020 at 08:38:42AM -0400, Luis Rojas G. wrote:

> Thanks for all the details. Wow, such nice implementation. It requires a
> deep knowledge of Kamailio.

Well, thank you -- I think that's much too generous. :-)

> I see, this is the part where the transaction is saved.
> 
>     mq_add("reinvite_q", "$T(id_index):$T(id_label)", "");
> 
> I didn't know much about pseudo-variables. I am reading now.
> 
> https://www.kamailio.org/wiki/cookbooks/5.3.x/pseudovariables#tmx_module_pseudo-variables

Pseudovariables are a confusing term, laden with historical baggage.

Historically, PVs referred to specific (and mostly read-only) variables
which target parts of the message buffer, e.g.

   https://www.kamailio.org/wiki/cookbooks/5.3.x/pseudovariables#ct_-_contact_header

But now they just refer to variables of all kinds, including the
namespace containers exposed by different modules (e.g. $T(...),
$shv(...), $dlg_ctx(...)), $vars, $avps, you name it.

> I guess, this approach could help me also in case of replies, not just
> requests, to add a delay to 200 OK to Invite.

I'm not sure that's possible. Remember that the request route is
fully imperative; a request is dropped into them and the list of actions
in the config script determines what happens to it, including any
relaying (or lack thereof).

onreply_routes, by contrast, are callbacks/hooks from normal, built-in
transaction-stateful behaviour; they expose the reply and allow you to
modify or drop it, but otherwise they are optional, because the proxy
already has an automatic reply-handling behaviour which will play out
without manual invocation from you.

> By the way, I assigned a value to "async_workers", and now the Invite (I was
> delaying any Invite, not just reinvite, just to test the api) is propagated
> delayed, which is great, but at the same time a
> 
> SIP/2.0 500 I'm terribly sorry, server error occurred (1/TM)

This sounds like possibly an attempt to relay twice, but I'm not sure.

-- Alex

-- 
Alex Balashov | Principal | Evariste Systems LLC

Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/