[asterisk-dev] SIP channel X Local Channel

[Matthew Jordan]

On Tue, Dec 1, 2015 at 3:00 PM, Gabriel Ortiz Lour <ortiz.admin at gmail.com>
wrote:

>
> Hi all,
>
>   Having trouble with understanding how chan_sip relates with chan_local.
> I know I'm using a very old asterisk version (1.8.19.0) but here is what
> I'm trying to do:
>
>   I'm using "use_q850_reason" to transport de HANGUPCAUSE from one * box
> to another, as I can see in the 2nd * log:
>
> ">> Using Reason header for cause code: 50"
>
> This number (50) came from the HANGUPCAUSE i've set on the 1st * box.
>
> The thing is that I used the AMI to generate a call using a Local channel,
> and I would like to receive that number in the "Reason" field of the
> OriginateResponse, so I would know the HANGUPCAUSE of the 1st * box.
>
> The problem is that the SIP channel in the case is never answered, I'm
> fighting with the code on chan_sip function "handle_response" and in the
> channel.c "__ast_request_and_dial", but I can't find where the two channels
> relate, where to get the "50" that I need...!
>
> Anyone could help me with some pointers on that?
>
>
You can't reach across channels from one channel driver to another in any
kind of safe fashion. That is, code in chan_sip cannot call or set code in
chan_local directly.

If one channel needs to inform another channel about some piece of
information, then it needs to do so using one of the built-in mechanisms
that pass information between channels. In your version, you're best off
modifying the control frame AST_CONTROL_HANGUP to pass the chan_sip
specific Reason code along with it. You'd do something like the following:
* Update ast_queue_hangup_with_cause to have a new reason parameter set by
chan_sip, and pass not just the hangup cause code but also the reason code
along with it. That would make f.data point to a structure containing both
cause codes, and have the datalen value be set in the frame to the size of
the struct.
* Update everyone who handles AST_CONTROL_HANGUP and extracts the cause
code out of it to get it from the new structure
* Update the origination routines to extract the Reason code out of its
handling of AST_CONTROL_HANGUP

That's probably your best path, anyway. It's important to note that another
way of doing this was implemented in Asterisk 11. There's a separate
control frame that handles cause code information that all channel drivers
can use to pass that information along to the core, and potentially further
if desired. That mechanism has a reasonable amount of work associated with
it, so it wouldn't backport well. If, however, Asterisk 11 is an option,
you may want to look into that functionality. The control frame that
handles cause code propagation (which could reasonably be extended for more
information) is AST_CONTROL_PVT_CAUSE_CODE.

-- 
Matthew Jordan
Digium, Inc. | Director of Technology
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at: http://digium.com & http://asterisk.org
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