Re: [Partysip-dev] Modification of Request URI in partysip?

[Aymeric Moizard]

On Mon, 15 Sep 2003, Walter Schober wrote:

> Hi!
>
> How far is Partysip RFC3261 conform? Because acc. to the RFC RFC 3261,
> 16.6, point 7: Determine the next-hop address, port, and transport the
> proxy should add a Via-Field only and must not change the Request URI.
> Otherwise the Invited user cannot be found.

First, I think a proxy have the right to modify the request-uri. I'm
pretty sure of that.

In your case, on the second proxy, it seems that both "labor.uta.at" and
"sip-proxy.labor.uta.at" resolv to the same ip. At least, this is the same
domain of users. In this situation partysip, (if well configured) would
understand that both uri:
sip:address@hidden and sip:address@hidden
points to the same user.

To make this work in partysip you just have to specify both names
in the "servername" configuration:

servername = sip-proxy.labor.uta.at, labor.uta.at

so that evry message coming with this uri is detected as a local uri
and partysip will loukup for a local user.

Of course, in your case (SRV record resolution), it would be a nice
feature to have the possibility to configure partysip so that it would
keep the uri intact and still use the new "sip-proxy.labor.uta.at"
name to send the request. As of today, this is not possible.

This feature would be a lot more interesting when you want to forward a
call to another proxy without modifying the request-uri. For example, the
filter plugin in partysip would be much more usefull if it was possible.

To conclude:

In your situation, my feeling is that the second proxy is guilty.
In other situations, it would be a nice feature to have the capability
to not modify the uri while fowarding a call to another proxy.

Aymeric

> My scenario (user in domain sip.labor.uta.at calls user in domain
> labor.uta.at):
> address@hidden -> INVITE address@hidden to outbound proxy of
> sip.labor.uta.at
>       INVITE sip:address@hidden SIP/2.0
>       Via: SIP/2.0/UDP 10.10.24.1:5061
>       From: Walter Schober
> <sip:address@hidden:5061>;tag=536123116
>       To: <sip:address@hidden>
>       Contact: <sip:address@hidden:5061>
>       Call-ID: address@hidden
>       CSeq: 28705 INVITE
>       Content-Type: application/sdp
>       User-Agent: X-Lite build 1047
>       Content-Length: 291
>
> Proxy of sip.labor.uta.at (partysip) -> DNS SRV -> SRV Reply:
>       sip-proxy.labor.uta.at is proxy of domain labor.uta.at
>
> Partysip changes the Request URI line to:
>       INVITE sip:address@hidden SIP/2.0
>
> The message
>       INVITE sip:address@hidden SIP/2.0
>       Via: SIP/2.0/UDP
> 192.168.3.2:5060;branch=z9hG4bKf0db4af6b864d6fae91f21c2ca9693d32.0
>       Via: SIP/2.0/UDP 10.10.24.1:5061
>       From: Walter Schober
> <sip:address@hidden:5061>;tag=536123116
>       To: <sip:address@hidden>
>       Call-ID: address@hidden
>       CSeq: 28705 INVITE
>       Contact: <sip:address@hidden:5061>
>       user-agent: X-Lite build 1047
>       Content-Type: application/sdp
>       Content-Length:   291
> Is forwarded to the next hop proxy, who don't know that user, but would
> have known the To: user :-)
>
> Shouldn't partysip just leave the Request URI as it was?
>
> Rgds,
> Walter
>