I think the called UA should:
1. Know that it will ask for authorization for incoming requests, so it can
slightly change its behavior when receiving CANCELs
2. 200 OK any CANCEL request that comes for any existing call leg.
3. If a 401 was already sent, the CANCEL changes nothing (CANCEL has no
effect on a terminated transaction)
4. If the 401 was not yet sent, the UA knows that it is about to ask fo
authorization. It should proceed with the authorization and send a 401 all
the same, instead of a 487.
I don't think this behavior would break anything.
EricT
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, February 28, 2001 12:30
> To: Arunachalam Venkatraman; [EMAIL PROTECTED]
> Subject: RE: [Sip-implementors] CANCEL with Authorization
>
>
>
>
>
> Ok, its like this :
>
> UA1 sends a INVITE to UA2 and this comes back to UA1 for authorization
> (401).
> Meanwhile another UA (UA3 say) sends a spurious CANCEL (with matching
> Call-ID, etc)
> to UA2 with an aim to CANCEL the call between UA1 and UA2.
> This is where authorization for CANCEL is needed.....
>
> Regards,
> Subhash.
>
>
>
>
>
> "Arunachalam Venkatraman" <[EMAIL PROTECTED]> on 02/28/2001
> 09:35:09 PM
>
> To: Subhash Ullal Nayak/HSSBLR, [EMAIL PROTECTED]
> cc:
>
> Subject: RE: [Sip-implementors] CANCEL with Authorization
>
>
>
>
> Why would you want to authorize the CANCEL and not also the preceding
> INVITE?
> If the INVITE was challenged and authorized, the CANCEL can
> carry the same
> credentials, correct?
> Am I missing something?
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]] On Behalf Of
> [EMAIL PROTECTED]
> Sent: Wednesday, February 28, 2001 12:08 AM
> To: [EMAIL PROTECTED]
> Subject: [Sip-implementors] CANCEL with Authorization
>
>
>
> Hi All,
> I have a doubt with regards to the following scanario :
>
> UserAgent
> | INVITE Cseq:1
> |<==================================
> | CANCEL Cseq:1
> |<==================================
> | 401 (CANCEL) Cseq:1
> |==================================>
> | CANCEL with Authorization Cseq:1
> |<==================================
> | 401 (CANCEL) Cseq:1 (WRONG !!)
> |==================================>
>
>
> Since the CANCEL (with Authorization header) is resent with the
> same Cseq as the original (unauthrorized) CANCEL, the remote
> retransmission logic mistakes it to be a retransmission of original
> CANCEL, and hence retransmits the 401.
>
> Should the CANCEL with Auth be sent with a higher Cseq ?
> As per the draft, the Cseq of the CANCEL should always match
> that of the INVITE that it is cancelling. How should this
> case be handled
> at the UAS end?
>
> Regards,
> Subhash.
>
>
> _______________________________________________
> Sip-implementors mailing list
> [EMAIL PROTECTED]
> http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
>
> _______________________________________________
> Sip-implementors mailing list
> [EMAIL PROTECTED]
> http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
>
>
>
>
> _______________________________________________
> Sip-implementors mailing list
> [EMAIL PROTECTED]
> http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
>
_______________________________________________
Sip-implementors mailing list
[EMAIL PROTECTED]
http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
