30 Aug
2010
30 Aug
'10
7:19 p.m.
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,