[OpenSER-Users] The Via Header of CANCEL Message

[fancy]

Hi Klaus:
RFC 3665 page 54 line 4:
   A CANCEL constructed by a
   client MUST have only a single Via header field value matching the
   top Via value in the request being cancelled.

and RFC 3665 at page 53:
   CANCEL is referred to as a "hop-by-hop" request, since it is
   responded to at each stateful proxy hop.

and RFC 3665 at page 21:
   Client: A client is any network element that sends SIP requests
         and receives SIP responses.  Clients may or may not interact
         directly with a human user.  User agent clients and proxies are
         clients.

So, for my opinion, the role of proxy in this case of RFC 3665 section 3.8 is a client when it sends CANCEL message to Bob.

If I misunderstand any RFC meanings, please correct me.
Thank you very much.

Best Regards,
Fangyu Ling


> fancy wrote:
>> According to RFC 3665 section 3.8 and RFC 3261 section 9,
>> there is only one via header in CANCEL message
>> (message F11, F13 at page 72 of RFC 3665).
> 
> Hi!
> 
> I could find it in RFC 3665, but not in 3261. Where exactly in RFC 3261
> is mentioned that the CANCEL has only 1 Via header?
> 
> Further, the example has only one Via header - but I could not find any
> definition if this is a MUST or not.
> 
>> How can I remove the 2nd via header?
> 
> You would have to modify tm module and change the code which generates
> the CANCEL message.
> 
> regards
> klaus
>