[OpenSER-Users] The Via Header of CANCEL Message

[Klaus Darilion]

Bogdan-Andrei Iancu wrote:
> Klaus,
> 
> CANCEL is hop-by-hop only in stateful processing and in this case, yes, 
> it has only on VIA. But if you have stateless processing, CANCEL is 

      ^^should

but in fact, also when using tm the CANCEL has 2 Via headers:

U 88.198.53.113:6060 -> 83.136.32.160:5060
CANCEL sip:klaus.darilion at nic.at43.at SIP/2.0.
Max-Forwards: 10.
Record-Route: <sip:88.198.53.113:6060;lr=on;ftag=d421fe7e>.
Via: SIP/2.0/UDP 88.198.53.113:6060;branch=z9hG4bKdd22.f7f861b6.0.
Via: SIP/2.0/UDP 
10.10.0.50:13946;received=83.136.33.3;branch=z9hG4bK-d87543-2e40397a3e383c6b-1--d87543-;rport=13946.
To: ...
...



regards
klaus

> end-2-end and it will have multiple VIAs...
> 
> Does 3665 obsoletes stateless SIP or it is just not covering it???
> 
> regards,
> bogdan
> 
> Klaus Darilion wrote:
>> Looks like it is defined clearly and openser is not 100% standard 
>> conform.
>>
>> regards
>> klaus
>>
>> fancy wrote:
>>  
>>> 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
>>>>
>>>>       
>>
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>