[asterisk-dev] redirecting lost over IAX

Discussion:

Kaloyan Kovachev

2018-10-29 15:33:19 UTC

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?

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Matt Fredrickson

2018-10-31 18:44:47 UTC

Permalink

Post by Kaloyan Kovachev
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.
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.
--
Matthew Fredrickson
Digium - A Sangoma Company | Asterisk Project Lead
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA

Kaloyan Kovachev

2018-11-01 14:13:11 UTC

Permalink

Post by Matt Fredrickson

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?

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

Matt Fredrickson

2018-11-02 20:23:20 UTC

Permalink

Post by Kaloyan Kovachev

Post by Matt Fredrickson

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)}
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
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?

A bug report would probably inappropriate as this would be a "feature
request", IMHO. I think this is as limitation in the IAX2 protocol.
The IAX2 RDNIS information element would either have to be extended to
add this information or an additional information element would have
to be created to contain this additional redirecting information.
--
Matthew Fredrickson
Digium - A Sangoma Company | Asterisk Project Lead
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA

Pavel Troller

2018-11-03 03:58:07 UTC

Permalink

Hello,

Post by Matt Fredrickson

Post by Kaloyan Kovachev

Post by Matt Fredrickson

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)}
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
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?

I'm afraid that it's really a problem with IAX2. But on the other side,
you can workaround it in your dialplan using IAX2 variables. Just set up
some IAX2 variables on the calling side and they will be received on the
called side and you can regenerate the correct REDIRECTING() information
from them. I'm using exactly this for transmitting
CHANNEL(transfercapability) over the IAX2 trunks:

For example, for the B-side:
exten => s,n,ExecIf($["${ATECH}" = "IAX2"]?Set(TRANSFERCAPABILITY=${IAXVAR(tfcap)}))
exten => s,n,ExecIf($["${TRANSFERCAPABILITY}" != ""]?Set(CHANNEL(transfercapability)=${TRANSFERCAPABILITY}))
...

With regards,
Pavel

Post by Matt Fredrickson
--
Matthew Fredrickson
Digium - A Sangoma Company | Asterisk Project Lead
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
--
_____________________________________________________________________
-- Bandwidth and Colocation Provided by http://www.api-digital.com --
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asterisk-dev mailing list
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Kaloyan Kovachev

2018-11-03 09:22:00 UTC

Permalink

Post by Pavel Troller
Hello,

Post by Matt Fredrickson

Post by Kaloyan Kovachev

Post by Matt Fredrickson

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)}
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
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?

The possibility for call loops is definitely a bug for me, but will open
it as feature request.

Post by Pavel Troller
I'm afraid that it's really a problem with IAX2. But on the other side,
you can workaround it in your dialplan using IAX2 variables. Just set up
some IAX2 variables on the calling side and they will be received on the
called side and you can regenerate the correct REDIRECTING()
information
from them. I'm using exactly this for transmitting
exten => s,n,ExecIf($["${ATECH}" =
"IAX2"]?Set(TRANSFERCAPABILITY=${IAXVAR(tfcap)}))
exten => s,n,ExecIf($["${TRANSFERCAPABILITY}" !=
""]?Set(CHANNEL(transfercapability)=${TRANSFERCAPABILITY}))
...
With regards,
Pavel

Thanks, that's the way i was going to workaround it and the question was
more about, is it a bug or misunderstanding on my side.
I have tested some time ago with SIP and as i recall there were no
problems with 'count' being incremented properly (will test again to
confirm), so this is IAX only problem

Post by Pavel Troller

Post by Matt Fredrickson
--
Matthew Fredrickson
Digium - A Sangoma Company | Asterisk Project Lead
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
--
_____________________________________________________________________
-- Bandwidth and Colocation Provided by http://www.api-digital.com --
https://www.asterisk.org/community/astricon-user-conference
asterisk-dev mailing list
http://lists.digium.com/mailman/listinfo/asterisk-dev