17 Mar
2010
17 Mar
'10
1:48 p.m.
Klaus Darilion wrote:
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
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).