Thank you Sunil for your help. -----Original Message----- From: Verma Sunil [mailto:[email protected]] Sent: Wednesday, September 29, 2010 12:37 AM To: Brandon W Yuille; [email protected] Subject: RE: [Sip-implementors] REFER Replaces and Referred-By
Hi Brandon, I think if UA1 is aware of both the call legs then it will be good to send Refered by as "[email protected]". But please note that this is not mandatory. As there could be many other mechanism to identify and Authenticate the Referring party. "Referred-By" is one of the mechanism to Authenticate if the request is originated from correct party. Please find more details in RFC 3891 section 3: If the Replaces header field matches an active dialog, the UA MUST verify that the initiator of the new INVITE is authorized to replace the matched dialog. If the initiator of the new INVITE has been successfully authenticated as equivalent to the user who is being replaced, then the replacement is authorized. For example, if the user being replaced and the initiator of the replacement dialog share the same credentials for Digest authentication [6], or they sign the replacement request with S/MIME [7] with the same private key and present the (same) corresponding certificate used in the original dialog, then the replacement is authorized. Alternatively, the Referred-By mechanism [4] defines a mechanism that the UAS can use to verify that a replacement request was sent on behalf of the other participant in the matched dialog (in this case, triggered by a REFER request). If the replacement request contains a Referred-By header that corresponds to the user being replaced, the UA SHOULD treat the replacement as if the replacement was authorized by the replaced party. The Referred-By header SHOULD reference a corresponding, valid Refererred-By Authenticated Identity Body [5]. The UA MAY apply other local policy to authorize the remainder of the request. In other words, the UAS may apply a different policy to the replacement dialog than was applied to the replaced dialog. In addition, the UA MAY use other authorization mechanisms defined for this purpose in standards track extensions. Extensions could define other mechanisms for transitively asserting authorization of a replacement. Regards Sunil Verma -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Brandon W Yuille Sent: Wednesday, September 29, 2010 5:18 AM To: [email protected] Subject: [Sip-implementors] REFER Replaces and Referred-By Hello, I'm having difficulty determining what the correct value of the "Referred-By" header is in the following scenario: - UA1 has two different usernames [email protected] and [email protected]. - UA1 has calls with both of its users [email protected] and [email protected] connected to two users on UA2 [email protected] and [email protected], respectively. - UA1 decides to transfer and replace [email protected] to [email protected]. - UA1 will then send a REFER request from [email protected] to [email protected]. The Refer-To header will be: "Refer-To: <sip:[email protected]:5060?Replaces=call-id-of-user2...>". Now, because the call to be replaced does not belong to [email protected], what would the value in the Referred-By header be? I've seen UAs that would set the value to be sip:[email protected] and other UAs would use sip:[email protected]. Thanks, Brandon _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
