[asterisk-dev] redirecting lost over IAX

[Kaloyan Kovachev]

На 2018-10-31 20:44, Matt Fredrickson написа:
> On Mon, Oct 29, 2018 at 10:33 AM Kaloyan Kovachev <kkovachev at varna.net> 
> wrote:
>> 
>> Hello list,
>>   I have followed the example from
>> https://wiki.asterisk.org/wiki/display/AST/Manipulating+Party+ID+Information
>> to unconditionally forward a call between two Asterisk instances
>> connected over IAX, but it seems there is a bug or the example is
>> incomplete.
>> 
>>   The setup is:
>>    Astersik A receives a call over DAHDI (libSS7) or SIP and forwards 
>> the
>> call to Asterisk B over IAX
>>    Astersik B checks the database and if redirecting is required sets 
>> the
>> REDIRECTING details as above and forwards the call to Astersik A as a
>> new call, again over IAX, which should dial out over SIP or DAHDI
>> 
>>   The problem is that only REDIRECTING(from-num) is populated and all 
>> the
>> rest is blank with count remaining 0, so no redirection info is
>> forwarded with the new call.
>>   Is there something else that needs to be set or it's a bug in the 
>> IAX
>> code to ignore the rest of the fields?
> 
> Which other fields specifically are you looking for?
> 
> It's quite possible the IAX2 protocol doesn't support some of the
> additional redirection info.
> 
> REDIRECTING(from-num) seems to get mapped to the RDNIS IE in IAX
> protocol land.  I guess it's going to just depend on what other fields
> you need or are looking for.

The problem is that the most important ones 'count' and 'reason' are not 
forwarded and most of the code does not even bother to check the rest if 
'count' is 0, so redirecting loops are possible if IAX is used somewhere 
in the path.

Just made a test redirecting my mobile number to my fixed one and 
checking 
${REDIRECTING(count)}/${REDIRECTING(reason)}/${REDIRECTING(from-all)}/${REDIRECTING(orig-all)}/${REDIRECTING(to-all)} 
with NoOp:
  libss7 ( on Asterisk A) sets the first 4 as received from the telco ( 
will need to patch it to also set the 'to' fields )
  the call is then forwarded to the second Asterisk ( B ) where the same 
NoOp only shows the 'from' field populates, so all the rest are lost
  on Asterisk B the call is further forwarded - 'count' is actually reset 
to 1 (allowing loops to be created) and 'orig' is lost

Expected behavior:
  all 5 fields received over SS7 should be forwarded over IAX to preserve 
the call divert information
  on subsequent redirection the 'count' should be incremented instead of 
being reset to prevent call loops

Should i open a bug report in this case, as it seems it's not something 
that i am doing wrong?

> 
> --
> Matthew Fredrickson
> Digium - A Sangoma Company | Asterisk Project Lead
> 445 Jan Davis Drive NW - Huntsville, AL 35806 - USA