[asterisk-users] asterisk 13.16 / pjsip / t.38: res_pjsip_t38.c:207 t38_automatic_reject: Automatically rejecting T.38 request on channel 'PJSIP/91-00000007'

[Joshua Colp]

On Sun, Jun 11, 2017, at 01:31 PM, Michael Maier wrote:
> On 06/11/2017 at 04:39 PM Joshua Colp wrote:
> > On Sun, Jun 11, 2017, at 11:34 AM, Michael Maier wrote:
> > 
> > <snip>
> > 
> >>>
> >>> PJSIP uses a dispatch model. The request is queued up, acted on, and
> >>> then that's it. The act of acting on it removes it from the queue.
> >>
> >> That's the *expected* behavior ... . I rechecked again and again. All
> >> existing tcpdumps. The "resent" package isn't part of any tcpdump
> >> (wireshark doesn't show it) - and during tcpdump no package was dropped.
> >>
> >>> The
> >>> only reason I'd expect to see it again is if there was a retransmission
> >>> or something somehow requeued it up - but I don't think we do that
> >>> anywhere. Not quite sure why it would be happening...
> >>
> >> But even if this package would have really been sent (as retransmission)
> >> - shouldn't there be another response? T.38 has been successfully
> >> enabled before and the faxclient has already sent a valid 200 ok
> >> including complete SDP information to asterisk.
> >>
> >> All in all it looks really odd to me.
> > 
> > Depends on how we handle that scenario. I don't think we have any tests
> > to cover it, so it's entirely possible that we wouldn't respond like
> > that. Why it's happening in the first place I still don't know though,
> > haven't seen anything like it.
> 
> Do you have any idea where to check if acted packages are really
> removed? Is there a way to check the pjsip-queue? Where could I start to
> look at? How does asterisk get them from the queue? And how does pjsip
> know that asterisk has processed them?

The distributor is in res/res_pjsip/pjsip_distributor.c, the distributor
function being the entry point. That function returning PJ_TRUE
indicates to PJSIP that it has been handled and no subsequent modules
should be called by that running thread. The distributor itself, though,
ends up executing things further in a worker thread using the distribute
function.

-- 
Joshua Colp
Digium, Inc. | Senior Software Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - US
Check us out at: www.digium.com & www.asterisk.org