You could ask on the sip-implementors mailing list.
regards
klaus
Iñaki Baz Castillo schrieb:
El Thursday 25 October 2007 11:15:41 Klaus Darilion escribió:
Iñaki Baz Castillo schrieb:
El Tuesday 23 October 2007 14:31:23 Klaus Darilion escribió:
And what says the RFC about a proxy which does parallel forking? Then
there may be multiple 180 ringing with multiple to tags. Which one
should be used?
Hi again.
Note that RFC 3261 assumes parallel forking in a different way as OpenSer
does. OpenSer just replies **one** final response to UAC but notes what
RFC 3261 says:
I think it does not assume a different way then Openser - this is just a
race condition: proxy forwards to A and B. A sends 200. proxy sends 200
to caller and CANCEL to B. If B picks up the phone and sends the 200 OK
before the CANCEL arrives then the proxy should forward the 200 OK from
B to the caller too and the caller has to deal to send a BYE to one of
the calls.
Further this race condition is not related to you CANCEL problem as if
there is already a 200 OK there will not be a CANCEL anymore, but a BYE.
Yes, it's different case.
In fact, I'm thinking about this CANCEL problem I can't find a solution
compliant with that RFC expects, it's just impossible:
RFC says that when UAC sends a CANCEL (with no to_tag) it must receive a "200
cancelled" with the to_tag of previous 180 or 183 (where there is a to_tag).
But in the other hand, CANCEL is hop by hop related, so the SIP device that
must reply to that CANCEL is the proxy and not the UAS. If the proxy
generates various branchs because parallel forking there could be various 180
with different to_tag, so in case of CANCEL how could OpenSer reply a 200
with every to_tags the UAC knows? that's why OpenSer replies with a new
to_tag.
If I'm right in the above explanation (could you confirm please?) then, what
should we do? open a bug for RFC? XDD
It's clear that Asterisk in pedantic mode (this is: matching tags) it doesn't
recognize the "200 cancelled" with new tag from OpenSer. Is it because
being "too much" RFC compliant?
Best regards.
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