[sr-dev] improving the dialog module

[Timo Reimann]

Klaus Darilion wrote:
>>>> Btw: how are dialogs in dialog module and transactions in tm module are
>>>> exactly identified? For example a response with proper callid and
>>>> fromtag
>>>> but faked Via branch, will it be accepted by dialog module but
>>>> ignored (drop
>>>> or stateless forwarding) by tm?
>>>
>>> Good question. IMHO it should be discarded as TM and dialog level (and
>>> not relayed stateless).
>>
>> The dialog module handles responses in the dlg_onreply() function which
>> is called by the tm module when the TMCB_RESPONSE_PRE_OUT (named
>> TMCB_RESPONSE_READY in 3.x) tm callback is triggered.
> 
> If dialog module receives this callback - will it check fromtag/callid
> or is the dialog already identified by the callback?

The latter is true: The dialog module does not need to check the dialog
identifier (From-tag, To-Tag, Call-ID) because the dialog that the
response is associated with will be given as one of the callback
parameters. When the dlg_onreq() function initially established the
dialog, it passed a pointer to the dialog data-structure (dlg_cell *) to
the callback registration function for TMCB_RESPONSE_PRE_OUT.

The whole effort of matching dialogs (including the dialog identifier)
is only done in dlg_onroute() which is called for every loose_route'ed
message, i.e., in-dialog request.


Cheers,

--Timo