[asterisk-dev] [Code Review] sip: ignore CANCEL request after having already received final response to INVITE

Klaus Darilion klaus.mailinglists at pernau.at
Wed Jun 9 06:35:30 CDT 2010

Am 08.06.2010 22:35, schrieb David Vossel:
> ----------------------------------------------------------- This is
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> https://reviewboard.asterisk.org/r/697/
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> Review request for Asterisk Developers.
> Summary -------
> RFC 3261 section 9 states that a CANCEL has no effect on a request to
> a UAS that has already given a final response.  This patch checks to
> make sure there is a pending invite before allowing a CANCEL request
> to be processed, otherwise it responds to the CANCEL with a "481
> Call/Transaction Does Not Exist".

I just wonder if this is necessary at all? IIRC the response code for 
the CANCEL is totally irrelevant. Relevant is only the response code of 
the INVITE transaction.

If a client receives a 200 OK on the INVITE, the dialog is established - 
regardless if the client sent CANCEL and received any responses.


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