[asterisk-dev] chan_zap questions

[Armin Schindler]

On Thu, 13 Jul 2006, Klaus Darilion wrote:
> Armin Schindler wrote:
> > On Thu, 13 Jul 2006, Klaus Darilion wrote:
> > > Armin Schindler wrote:
> > > > On Wed, 12 Jul 2006, Klaus Darilion wrote:
> > > > > > Maybe an additional subclass
> > > > > > AST_CONTROL_AOC
> > > > > > should be introduced.
> > > > > Thats what I did and it works fine. But ast_indicate_data
> > > > > requires a
> > > > > ast_channel as first parameter. If FACILITY is received on
> > > > > leg2, I
> > > > > have to
> > > > > find out the ast_channel of leg 1 to indicate on the proper
> > > > > channel.
> > > > > Fur this
> > > > > purpose I still use ast_bridged_call. Any other suggestion?
> > > > No, don't use ast_indicate*() directly, just use the normal *read
> > > > function to give this CONTROL frame to asterisk. The asterisk
> > > > code
> > > > (bridge or dial-before-bridge) will forward this CONTROL frame to
> > > > the
> > > > other leg. 
> > > Hi Armin!
> > > 
> > > How are the frames handled in Asterisk - synchron or asynchron? For
> > > example,
> > > in chap_zap I allocate a buffer, and queue a control frame whose data
> > > member
> > > points to the buffer. Once chan_zap receives the control_frame, it
> > > will read
> > > data from this buffer. Is this safe?
> > 
> > The data of such an control frame is placed like the voice data to
> > f->data and f->datalen (f->data must point to the buffer).
> > You should assume asynchron, because on certian parts there are queues
> > and pipes used, so it's not synchron.
> > The f->data pointer must be valid until the other leg has read it.
> > So maybe an malloc'ed space should be used.
> 
> I've just checked ast_queue_frame - looks like the whole frame including the
> data buffer will be copied in ast_frdup
> (http://www.asterisk.org/doxygen/frame_8c.html#a22)
> 
> So there shouldn't be a problem.

That's right. If you use ast_queue_frame(), it's no problem.
(don't forget the free the frame afterwards ;-)

> I just hadd to extend dial.c to recognize the
> AOC control frames.

I think you mean apps/app_dial.c !?
But it is at least ast_generic_bridge() in channel.c too.

Armin