Hi,
Reposting as i did not receive a response...
Thanks in advance,
Subhash.
[EMAIL PROTECTED]
om
Sent by: To
sip-implementors- Cullen Jennings <[EMAIL PROTECTED]>
[EMAIL PROTECTED] cc
ia.edu [EMAIL PROTECTED],
Jon Peterson
<[EMAIL PROTECTED]>, Mark
05/26/04 05:35 PM Watson <[EMAIL PROTECTED]>
Subject
Re: [Sip-implementors]
Interpretation of 'hint' in
thePreferred-Identity
Hi Cullen,
Thanks for your response. Its the example with
[EMAIL PROTECTED] that got me confused. From the example
it seemed like there were no clear guidelines on what
part of the PPI should be the hint (the user suggests
[EMAIL PROTECTED] and the proxy inserts [EMAIL PROTECTED] !)
A basic implementation would probably do a full URL
comparision of the PPI header with the list of configured
identities for the user and choose the one that exactly
matches. My concern is that nowhere does the draft suggest
explicitly how the hint is to be interpreted. Can we assume
that a proxy will always do a URL comparision and choose the
matching URL. Or is it possible that some proxies will only
look at the user part, etc. as per their policy. If its the
latter, then wouldn't it be better if the PPI contains a
parameter to indicate which part of the URL should be used as
the hint.
For example:
P-Preferred-Identity: "Cullen Jennings"
<sip:[EMAIL PROTECTED]>;hint=userpart
or
P-Preferred-Identity: "Cullen Jennings" <sip:[EMAIL PROTECTED]>;hint=fullURL
Without the above parameter and without explicit text in the
RFC as to how the proxy should use the PPI to pick the right PAI,
is it correct to say that the implementation will differ
from proxy to proxy ? Thanks in advance for your comments.
Regards,
Subhash Nayak
Hughes Software Systems
http://www.hssworld.com
Cullen Jennings
<[EMAIL PROTECTED]
> To
"Goud, Venkat Ramana (Venkat) **
05/21/04 10:14 PM CTR **" <[EMAIL PROTECTED]>,
<[EMAIL PROTECTED]>
cc
<[EMAIL PROTECTED]>,
Mark Watson
<[EMAIL PROTECTED]>, Jon
Peterson <[EMAIL PROTECTED]>
Subject
Re: [Sip-implementors]
Interpretation of 'hint' in
thePreferred-Identity
The example with vovida.org may be a typo :-)
The idea is pretty simple. Let's say that I can take on the identity
[EMAIL PROTECTED], [EMAIL PROTECTED], and [EMAIL PROTECTED] The system
may be able to verify that I can be any one of those but it does not know
wish one I want to use for this particular call. The hint can indicate
which
one I want to use.
If I give a hint that I want to be [EMAIL PROTECTED], the system will no allow
this because it is not valid for me.
Sorry for the sloppy details in this response but hope it helps,
Cullen
On 5/15/04 3:53 AM, "Goud, Venkat Ramana (Venkat) ** CTR **"
<[EMAIL PROTECTED]> wrote:
> 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
>
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