Subject: [SIP] Error reporting using via header in UDP

From: "M. Ranganathan" <[email-masked]>
Date: Tue, 07 Nov 2000 11:46:37 -0500

Hello!

(Im going to sound like a lawyer again. Yech! :-)). 

Here is the passage from the RFC that I am trying to interpret. In
section 1.4.3:

 If the client sent the request via unicast UDP, the response is sent
 to the address contained in the next Via header field (Section 6.46)
 of the response. 

I use the term client to refer to the originator of a message. My
questions / assumptions are below: 

1. The address in the first via header need not necessarily be the peer
address that the server reads from the udp socket when it gets the
message. Of course, it is in the client's best interest to use a
meaningful address.

2. If the server reads a request that is badly formatted except for the
via header, it can silently drop the message if it wants. In general,
the server is just being nice by returning error messages for udp
requests and is not obliged to do so.

Thank you in advance for your replies.

Regards,
Ranga.

-- 
M.Ranganathan
NIST Advanced Networking Technologies Group,
100 Bureau Drive, Stop 8920, Gaithersburg, MD 20899. 
Tel: 301 975 3664 Fax: 301 590 0932

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From: Gethin Liddell <[email-masked]>
Date: Wed, 8 Nov 2000 09:20:15 +0000

> message. Of course, it is in the client's best interest to use a

If a server receives a message and the originating host address does
not match the value in the top most via header, it adds a received
parameter which identifies the IP address of the client.  This received
parameter is used when routing messages back up stream.  Is that what
you're asking about?
    
> requests and is not obliged to do so.

Is that a question or a statement?  I would expect an error response to
be sent if the message can be decoded enough to generate a valid
response.

-- 
Gethin Liddell
Ubiquity Software Corporation

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

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From: "M. Ranganathan" <[email-masked]>
Date: Wed, 08 Nov 2000 10:10:33 -0500

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From: Gethin Liddell <[email-masked]>
Date: Wed, 8 Nov 2000 16:30:22 +0000

> 2. If the server reads a request that is badly formatted except for
> the via header, it can silently drop the message if it wants. In
> general, the server is just being nice by returning error messages
> for udp requests and is not obliged to do so. 

> Is that a question or a statement?  I would expect an error response
> to  be sent if the message can be decoded enough to generate a valid 
> response.

> Is this a requirement  or a recommendation?  (i.e. are silent
> failures disallowed by the spec. ) 

well the spec only says SHOULD when talking about the 400 response so
no its not mandatory

http://www.ubiquity.net