The implementation will make changes in BlueZ, ConnMan and oFono. Most of the changes will be inside oFono. There, we need to use the AT command parser and the  PPP stack (recently added to the oFono repo). The work consist on integrate everything and implement the missing parts of the AT command parser and the PPP stack, and the DUN agent.

On the BlueZ part the work will be the service export for DUN Data Terminal role and and the DUN Agent server to register agents and pass the RFCOMM file descriptor. For testing purposes we can use the Serial API in the beginning. That work is very similar to what we did for the HFP this year.

The ConnMan integration: ConnMan will setup the NAT and the  Internet connection. The DUN integration on ConnMan is similar to the PAN integration(still a work in progress) , so we can reuse part of that implementation.

That’s it.  I’ll post updates here during the development of the project. Now let me code. ;-)

Also, congratulation to the others Unicamp (University of Campinas) students that were accepted on GSoC too. :-)

On the BlueZ side a new API was designed using the fd-passing feature of DBus 1.3.  This new API uses the concept of Agents where oFono plays the Agent role.  In the HFP case the Agent role is to handle the AT engine stuff while BlueZ will only take care of the RFCOMM and SCO connections.

The RFCOMM socket is passed to the Agent in oFono via DBus, then oFono uses it to send and receive the AT commands to establish a Service Level Connection, i. e., make the handshake procedure. If it succeeds oFono will be ready to make and answers calls. Your HFP enabled phone will show up as a  modem in oFono, like any other oFono modem.

The work was initially based on patches from Zhenhua Zhang(from Intel) and the audio interaction to handle the SCO data inside Pulseaudio was done by João Paulo Rechi Vita(from ProFUSION too). He also did the demo video below.

After pairing the devices using some BlueZ agent like kbluetooth or gnome-bluetooth, you’ll be able to see the modem in oFono and you can enable it ( i. e., make the handshake procedure to establish an HFP Service Level Connection) using the enable-modem script from the test directory on oFono source.

In order to test this you need the Audio Gateway interface enabled in BlueZ. For that, edit your /etc/bluetooth/audio.conf  and add “Enable=Gateway” to it.

HFP code is already merged upstream on the BlueZ and oFono trees. The API is described in doc/hfp-api.txt in BlueZ source.