Re: [RFC] voicecall: Allow second stage string on Dial()

[Denis Kenzior <denkenz@gmail.com>]

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Hi Lucas,

 > Humn...  I was guided by this comment in dial_handle_result():
>
> /*
>   * Dial request may return before existing active call
>   * is put on hold or after dialed call has got active
>   */
>
> So either I misunderstood what "after dialed call has got active" means or:
>
> ATD...;
> CALLSTATE: dialing
> CALLSTATE: alerting
> CALLSTATE: active
> OK
>

I've not seen this behavior, in theory it is possible.  But mostly that 
comment is about the case of three way calls.  Even then, we can simply 
run the dial string from the ATD callback.

>> The user can disconnect / switch the call to a Held state mid-way for
>
> mid-way while the tones are being sent, right?

Correct.  Try it on an iPhone for example.  Your tone will never get sent.

>
>> example, in which case all the tones are lost.  I think that this is just
>> fine, unless you have some nice way of presenting this fact to the user?
>
> I was thinking about a property SecondStageNumber that is set once we
> start sending it and then if it errors out, we set it to "error" or
> the like.
> Or we can update the property like below:
>
> SecondStageNumber=1234567AB
> ...
> SecondStageNumber=4567AB
> ...
> SecondStageNumber=AB
> SecondStageNumber="failed"
>
> Just throwing away some ideas... We could do it with signals too:

Throw these away ;)  I don't see the point in setting the error.  As I 
said, do you have a user usecase for it?

>
> SendToneStarted(string complete_number)
> SendToneUpdate(string partial_number)
> SendToneEnd()
>

This is much more likely, however having three signals is way too much, 
the TODO proposal is likely enough.

> I think this would cover the other TODO item?
>
> "
> - Provide feedback of sent DTMF tones. Emit SendingTones signal if modem can
>    provide approximate starting and stopping times for DTMF tones. Signal
>    argument contains a string of DTMF tones to be sent, or empty string when
>    all tones has been sent."
>
> Or what the TODO item says.
>

AFAIK the original reason this was here was to have the Audio Framework 
generate the DTMF tones locally.  It was not intended for user feedback.

The question is how you want your UI to look like.  For example, do you 
want to show the progress of the DTMF tones (e.g. text changing from 
gray -> black) as they are being dialed?

>>
>> Another interesting case to consider is what should happen if we have a
>> Three-Way call, start a DTMF queue and then swap calls.
>
> Right now we continue sending the tones, right? We could change
> voicecall.c to associate a queue to the active call and throw it away
> when this  call change state, setting the property to error as above.
>

The trouble is DTMFs can be applied to a dialing call as well, though 
I'll need to do some digging to understand how/why.

>
>>
>>

<snip>

>>> @@ -1570,12 +1601,24 @@ static DBusMessage *manager_dial(DBusConnection
>>> *conn,
>>>
>>>          vc->pending = dbus_message_ref(msg);
>>>
>>> +       tones = strpbrk(number, "pP");
>>> +
>>
>>
>> Doing this is not safe, you might want to sanitize this input.
>
> How so? Searching for "pP" is as safe as calculating the length in
> valid_number_format().

The number being dialed is sanitized in voicecall_dial.  You do not 
sanitize the tones at all.  tone_queue will reject invalid input, but 
then you should not even accept an invalid dial string here in the first 
place.

Regards,
-Denis