[SR-Users] Share variable into reply route.

[Alex Balashov]

Hello Zhan,

$var()s are ephemeral variables intended for use only in the context of
processing a single SIP message. Also, they live in the private memory
("package memory") of a single SIP worker process.

Requests (route) and replies (onreply_route) are different kinds of
messages, and moreover, they are very likely to be handled by different
child processes. So, a $var set in a request route isn't going to show
up in an onreply_route. Furthermore, $vars have a global scope and
aren't individuated to a given SIP message flow (i.e. a transaction).

What you want is to use AVPs:

https://www.kamailio.org/wiki/cookbooks/5.2.x/pseudovariables#avp_id_-_avps

Or their nonscalar cousin, XAVPs. 

Either way, these are explicitly transaction-persistent, so they will be
visible from any route that touches a message associated with the
transaction in which they were set. Just use this instead:

   $avp(UniqueId) = $hdr(X-UniqueId);

and I think you'll get the behaviour you expect.

-- Alex

On Mon, Sep 09, 2019 at 11:43:27PM +0300, Zhan Bazarov wrote:

> Hello,
> 
> we ran into a trouble with sharing variable into reply route...
> 
> We are going to match asterisk's uniqueid with rtpengine records like this:
> 
> route[from_asterisk]{
> $var(UniqueId)=$hdr(X-UniqueId);
> $var(rtp_flags) = $var(rtp_flags) + "
> label={uid:$var(UniqueId),stream:outgoing} record-call=on";
> 
>  rtpengine_manage($var(rtp_flags));
> }
> 
> reply_route[from_pstn]{
>  rtpengine_manage("replace-origin replace-session-connection ICE=remove
> RTP/AVP rtcp-mux-demux label={uid:$var(UniqueId),stream:outgoing");
> }
> and it doesn't work... The one possible way what we found its using $shv
> instead of $var... But its unsecure way, cuz it may confus our bussines
> logic...
> 
> Do you have any idea how to implement this?
> Many thanks!

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-- 
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/