Subject: [SIP] received param

From: Dvir Oren <[email-masked]>
Date: Thu, 28 Sep 2000 21:10:03 +0300 (IDT)

I ran into a problem with my SIP implementation when a UAS returned a
reply to a Proxy with a receiver-tagged Via.  The Proxy then wanted to 
check whether this reply is for itself, or to be proxied.  It first
looked at the first Via to see if it's its own Via.  It found the
receiver-tagged Via, and tried to compare it with what it knows about
itself.

What I did at this point is compare the IP addresses.  Unfortunately,
the DNS had only one of the IP addresses of the Proxy, while the UAS
saw the request coming from a different IP.  So, the Via's did not
match.

I did some hack which ignores the recieved tag.  I personally don't
like it.

Any other solutions?

-- 
Dvir Oren               <[email-masked]>
Lucid VON Ltd.     <http://www.lucidvon.com>
9 Saloniki St.,        Tel-Aviv       Israel
Tel:  +972 3 644 3038  Fax:  +972 3 644 3039

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---

From: "Jo Hornsby" <[email-masked]>
Date: Fri, 29 Sep 2000 09:34:17 +0100

> saw the request coming from a different IP.  So, the Via's did not

Isn't your DNS potentially flawed, then?  I don't see why the proxy
can't know all the IP addresses that it's using (in the simplest
case, just make them configurable).

> I did some hack which ignores the recieved tag.  I personally don't

Via-received was intended (whether it really works is another matter)
to work around NATs, thus it doesn't seem unreasonable that a client
should ignore it (if the client knew what IP it would appear as to the
server, why didn't it just put that IP in the Via from the beginning?).

> Any other solutions?

Yes -- use the branch parameter.

 - Jo.

---

From: Gethin Liddell <[email-masked]>
Date: Fri, 29 Sep 2000 09:57:19 +0100

> receiver-tagged Via, and tried to compare it with what it knows about

I don't think that you should be making this comparison at all.

Section 2.1, although specifically talks about sip url, does say that
when comparing parameters:

"If a com-ponent is omitted, it matches based on its default value.
(For example, otherwise equivalent URLs without a port specification
and with port 5060 match.) Components not found in both URLs being
compared are ignored."

applying this ethos to headers, then as your via does not contain a
received parameter, you should not be making this comparison.  Just
compare on the sent-protocol, sent-by and any parameters you add (such
as branch)

HTH

-- 
Gethin Liddell
Ubiquity Software Corporation

http://www.ubiquity.net
mailto:[email-masked]

---

From: "Raja Sekhar" <[email-masked]>
Date: Fri, 29 Sep 2000 09:09:21 -0400

hi Dvir Oren
 This is the raj here . I have few questions about it . Weather your
register message via tag has  considering the local proxy or IP address of u
r system .
There should be a matching of IP address on the proxy accordingly DNS lookup
takes place . So please clear  your register message Via tag entry

thanq
rajasekhar-voicecore

-----Original Message-----
From: [email-masked]
[mailto:[email-masked]]On Behalf Of Dvir Oren
Sent: Thursday, September 28, 2000 2:10 PM
To: SIP
Subject: [SIP] received param

Any other solutions?