asterisk users - Jun 2017 - asterisk 13.16 / pjsip / t.38: res_pjsip_t38.c:207 t38_automatic_reject: Automatically rejecting T.38 request on channel 'PJSIP/91-00000007'

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.

-- 
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

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?



Thanks,
Michael

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