[asterisk-dev] [Code Review] Properly route responses according to the Via headers in the request

Olle E. Johansson oej at edvina.net
Thu Dec 23 12:38:17 UTC 2010

23 dec 2010 kl. 09.48 skrev Alex Hermann:

> On Thursday 23 December 2010, Olle E Johansson wrote:
>>> On 2010-12-23 02:11:36, Olle E Johansson wrote:
>>>> THis is wrong and not according to the RFC. Please re-read the
>>>> section I referred you to. A UAC should always respond
> UAC's don't respond, they send requests. UAS's respond.
Nitpicking, but agreed.
>>>> to the sender's IP address and port.
> Wrong, only to the address, the port is taken form the Via header unless 
> rport is used.
Please read the RFC.
>>>> If you make the nat=yes behaviour for
>>>> SIP the default, you are right on. Via headers are used for proxies,
>>>> since a proxy do not have to keep state and remember the sender. The
>>>> proxy handling the response might not even be the same as the one
>>>> processing the request.
> Wrong, replies always follow the exact same path back along proxies as the 
> request has followed on its way to the UAS.
>>>> Via headers is not for UA's unless you have
>>>> a transport machine that adds  an Via header when receiving the
>>>> packet and delivers it up to the the transaction layer. If that's
>>>> the case, the transaction layer routes the response to the top via
>>>> header, added by the incoming transport. Since we have none of that,
>>>> we just respond to the sender. Period.
>> I haven't figured out from your e-mails whether or not you had a route
>> set. If you had a route set from the initial transaction and get the
>> INFO from another address, we need to figure out what to do.
>> If there's no route set (no proxy added a record-route header to request
>> to stay in the signalling path) then only the initial transaction goes
>> through the proxy and we should respond directly to the device.
> For replying to a request, it is completely irrelevant if there is a proxy 
> in the path or whether is is statefull, stateless, has or has not record-
> route headers.
You totally do not understand or do not want to read what I wrote. 
This part was not about responses, but about the INFO that was sent directly. 
Please be more careful before you respond.

> Your last 2 emails only add to the confusion as they contradict the rfc's.
The same to you. Let's try to clear this up.
> Proper reply behaviour is described in 18.2 of rfc3261 and rfc3581 and is 
> certainly no rocket-science. Short versions have already been mailed in this 
> thread.
But the wrong quotes.

> -- 
> Alex Hermann
> --
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* Olle E Johansson - oej at edvina.net
* Cell phone +46 70 593 68 51, Office +46 8 96 40 20, Sweden

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