On 4/11/12 6:29 AM, Keerthi Srinivasan wrote:
> Dear All,
>
> What could be the Proxy and Registrar behavior for the Unknown URI schema
> in From, To, Contact and Request URI?
>
> Here is the sample SIP message.
>
> 1. Unknown URI schema in Request URI
>
> REGISTER* test:example.com<sip:example.com>  *SIP/2.0
> To: sip:[email protected]
> From:<sip:[email protected]<http://www.example.com/>>;tag=3234233
> Call-ID: [email protected]
> CSeq: 234902 REGISTER
> Max-Forwards: 70
> Via: SIP/2.0/UDP 192.0.2.21:5060;branch=z9hG4bKkdjuw
> Contact:<sip:[email protected]>
> l: 0

The request URI isn't just an unknown uri scheme - it is syntactically 
incorrect. (The "<" and ">" aren't valid.)

There isn't any good way to proceed with this. So the request ought to 
be failed.

> 2. Unknown URI schema in From Header
>
> REGISTER sip:example.com<sip:example.com>  SIP/2.0
> To: sip:[email protected]
> From:<*test:[email protected]<http://www.example.com/>*>;tag=3234233
> Call-ID: [email protected]
> CSeq: 234902 REGISTER
> Max-Forwards: 70
> Via: SIP/2.0/UDP 192.0.2.21:5060;branch=z9hG4bKkdjuw
> Contact:<sip:[email protected]>
> l: 0

The From-URI is syntactically incorrect. An attempt to form a response 
to this will generate either a syntactically incorrect one, or else one 
that has a From-URI different from the request. There are no good 
actions. So I guess you can take your pick: drop the request without 
response, respond with a From copied from the request, or respond with a 
 From that is patched up in some way. I wouldn't expect any good outcome 
regardless of which option you take. The UAC is broken and needs to be 
fixed.

> 3. Unknown URL schema in To Header
>
> REGISTER sip:example.com SIP/2.0
> To: *ram:[email protected]*
> From:<sip:[email protected]<http://www.example.com/>>;tag=3234233
> Call-ID: [email protected]
> CSeq: 234902 REGISTER
> Max-Forwards: 70
> Via: SIP/2.0/UDP 192.0.2.21:5060;branch=z9hG4bKkdjuw
> Contact:<sip:[email protected]>
> l: 0

Same answer as for 2.

> 4. Unknown URI Schema in Contact Header
>
> REGISTER sip:example.com<sip:example.com>  SIP/2.0
> To: sip:[email protected]
> From:<sip:[email protected]<http://www.example.com/>>;tag=3234233
> Call-ID: [email protected]
> CSeq: 234902 REGISTER
> Max-Forwards: 70
> Via: SIP/2.0/UDP 192.0.2.21:5060;branch=z9hG4bKkdjuw
> Contact:<*test:[email protected]*>
> l: 0

Contact URI is syntactically incorrect. At least in this case its 
possible to leave it out of the response, so you can send a 
syntactically correct response.

A proxy doesn't need to process the Contact, so it could forward the 
request, or it can reject it.

A registrar could reject the request, or if it wants to be extremely 
tolerant it could simply ignore the Contact and process the REGISTRAR as 
a poll - returning the contacts that are currently registered.

In all of the cases above, if an error response is sent then I think 400 
is the best that you can do, because there is really a syntax error, not 
just an invalid uri scheme.

        Thanks,
        Paul

> These message are pass through proxy to registrar. Can you please anyone
> help me in the *Proxy and Registrar Behavior*.????

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