[OpenSIPS-Devel] [ opensips-Bugs-2685610 ] OPTIONS problem

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Bugs item #2685610, was opened at 2009-03-12 22:37
Message generated for change (Comment added) made by bogdan_iancu
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Category: core
Group: None
>Status: Closed
>Resolution: Invalid
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: OPTIONS problem

Initial Comment:
I have an event where two packets arrive - the first being an ACK from an reINVITE / 200 OK and the second being an OPTIONS packet.   When these are forwarded, they are actually sent in reverse order, the OPTIONS request is sent before the ACK is sent (the CSeq for the ACK is 2 and the CSeq for the OPTIONS is 3).   This is breaking the call as the CSeq is received out of order on the far-end.   I've used Wireshark to actually see the incoming order and the outgoing packets sent.   I'm using OpenSIPS v. 1.4.4 (no TLS) on a FreeBSD (64-bit) 7.1 machine.

I've even tried running SER 0.9.6 and the same thing occurs.

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>Comment By: Bogdan-Andrei Iancu (bogdan_iancu)
Date: 2009-03-13 11:25

Message:
This is not a bug in OpenSIPS, but a issue with SIP - and the guilty entity
is the UAC as it sending the ACK and OPTIONS to fast (no delay between). In
SIP, no mid hop or not even the network (for UDP) can guarantee that order
for sending the request is the same when receiving.

As simple work around you can do is to detect the scenario and if an
OPTIONS is received, use the sleep() function from the cfgutils module:
  http://www.opensips.org/html/docs/modules/1.4.x/cfgutils.html#id228339

Regards,
Bogdan

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