[SR-Users] Duplicate INVITE Handling

[Uriel Rozenbaum]

Hi,

Check t_check_trans() from tm module.

It does all on its own

http://kamailio.org/docs/modules/1.5.x/tm.html#id2509242

Cheers,
Uriel

On Mon, Aug 30, 2010 at 2:19 PM, Geoffrey Mina <geoffreymina at gmail.com> wrote:
> Hello,
> I have a question about what the proper way to handle a duplicate
> presentation of an INVITE is.  On occasion I am seeing some packet loss
> and/or timing issues which are causing some of my end-points to retransmit
> the INVITE.  Here is what I am doing in the most basic sense:
>
>
> ITSP (Bandwidth.com) --> INVITE --> KAMAILIO --> DISPATCHER --> Asterisk
> (B2BUA)
>
>
> I am seeing Bandwidth.com send an INVITE which I already received.   I keep
> track of all running transactions in a htable which has a key of
>
> $ci::$cs::$ft (as per RFC 3261).
>
> If I get an invite for something which already has a key in the hashmap, I
> am currently sending a  "482 Loop Detected", but I don't think that is
> correct as it causes the whole call to tear down instead of letting it
> continue and assuring Bandwidth.com that I received the initial INVITE and
> am currently working on it.
>
> This is what I am currently doing:
>
>     ##
>     ## Check to make sure we don't already have an active
>     ## transaction for this call-id, c-seq, and from-tag
>     ## RFC3261 - 8.2.2.2
>     ##
>     ## We are going to add a key for this unique record if one
>     ## doesn't already exist.  The key automatically times out
>     ## after 30 seconds, so we need not worry about cleanup
>     ##
>     if($sht(loop_check=>$ci::$cs::$ft) == null){
>         xlog("L_INFO","No transaction found, adding to our hashtable\n");
>            $sht(loop_check=>$ci::$cs::$ft) = 1;
>     }else{
>            xlog("L_ERR","Loop Detected: $ci::$cs::$ft\n");
>         sl_send_reply("482","Loop Detected - Duplicate Session
> Presentation");
>            exit;
>     }
>
> Can I just swallow the second INVITE and do an exit; in my script?
> Should I do an sl_send_reply(100,"Trying")?
>
> Any advice would be greatly appreciated.
>
> Thanks,
>
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