Hi Subhash, The criteria itself is open to implementations but I assume based on the authentication information proxy need to somehow identify a list of identities that could be validly associated with that user. For ex, this could either be a database of its own or a database provided by other component on which it relies. Otherwise malicious UACs might indicated false identities in PPI. In the example if PPI is something like P-Preferred-Identity: "John Doe" <[EMAIL PROTECTED]>, proxy need to verify that this is not a valid identity for user fluffy and either it rejects this requests or inserts [EMAIL PROTECTED] or [EMAIL PROTECTED] The reason the example includes [EMAIL PROTECTED] might be that the domain being forwarded to is vovida.org and there might be an implicit trust relationship between those two.
There are some valid reasons where proxy might need to ignore PPI and insert a totally different PAI which has no semblance to PPI at all. When forwarding requests across domains, proxy might need to insert a PAI which a user is not aware of or might need to provide a different PAI to the forwarding domain to provide certain features. -Venkat -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Friday, May 14, 2004 10:21 AM To: Goud, Venkat Ramana (Venkat) ** CTR ** Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: RE: [Sip-implementors] Interpretation of 'hint' in thePreferred-Identity Hi Venkat, My question is how does the proxy recognize if the PPI is a valid identity for the user ? From the example, it seems like P-Preferred-Identity: "Cullen Jennings" <sip:[EMAIL PROTECTED]> results in the proxy inserting: P-Asserted-Identity: "Cullen Jennings" <sip:[EMAIL PROTECTED]> In this case, how did the proxy decide that the PPI was a valid or invalid identity ? Ideally it should have inserted [EMAIL PROTECTED] but it seems to have inserted [EMAIL PROTECTED] Is it correct to assume that it did a _full_URL_comparision_; did not find a match; and hence inserted the closest identity it could find to the one suggested in the PPI ? Again, in deciding "closest identity" what was the criteria - the PPI header does not allow the client to suggest which part of the header is to be used as the hint (display-name or userinfo part or whatever)...is that left open to implementations ? Thanks, Subhash. "Goud, Venkat Ramana (Venkat) ** CTR **" To <[EMAIL PROTECTED]> <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]> 05/13/04 06:28 PM cc <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]>, <[EMAIL PROTECTED]> Subject RE: [Sip-implementors] Interpretation of 'hint' in thePreferred-Identity I think section 6 is pretty clear on this. PPI is only a suggestion/request so I guess its up to the proxy as to whether to use the hint or not. If there is a P-Prefferred-Identity header: 1) If the proxy recognizes it as a valid identity for that user and if there is no local policy for the proxy suggesting some other PAI, then it can use the one in the PPI header. 2) If the proxy does not accept the PPI as valid identity for the user then it may either reject that request or use a PAI constructed based on its local policies. -Venkat -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of [EMAIL PROTECTED] Sent: Thursday, May 13, 2004 8:33 AM To: [EMAIL PROTECTED] Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: [Sip-implementors] Interpretation of 'hint' in thePreferred-Identity Hi, RFC 3325 states that a proxy may use the P-Preferred-Identity in an incoming request as a hint to choose among multiple identities that are configured for a user. The example section shows an example where the user suggets that he prefers to use the identity [EMAIL PROTECTED] But the proxy inserts [EMAIL PROTECTED] in the forwarded request. The RFC does not clearly specify how the proxy should interpret the 'hint' that is provided. From the syntax of the P-Preferred-Identity and the P-Asserted-Identity it seems that one should do a URL comparison to choose the correct PAI header. But from the example, it seems like either the display-name or the userinfo part is being used to choose the correct PAI header. Can someone provide some clarity or point to discussions which indicate how the 'hint' should be interpreted. Is it that no rules have been laid down so that it is left to individual implementations ? In that case, could implementors/authors suggest as to how one would normally interpret the hint i.e. by comparing which part of the P-Preferred-Identity header. Thanks in advance, Subhash Nayak Hughes Software Systems http://www.hssworld.com _______________________________________________ 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
