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From:   Mihai Emilian <be.mihai22@gmail.com>
Date:   Thu, 18 Mar 2021 19:04:20 +0100
Message-ID: <CAP_L5iPOJXpATznLxmg1LArNaoLaDEr-zkYRwryLK8OBexwf0A@mail.gmail.com>
Subject: Developing and extending Agent1
To:     linux-bluetooth@vger.kernel.org
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Dear community,

I am attempting to create a service that extends the functionality of
Bluez Pairing. I want to rewrite some of the functionality for
different paring methods (capabilities).

I read [this blog which uses Qt][1] to generate the code to create the
base code for the agent.

I used `gdbus-codegen` to generate the C code (like this[2]), using
the XML given in the blog in [1].

Then, in my main function, I acquired a SYSTEM BUS name and exported
all objects, including an object manager. My setup now looks like
this:[3]

Finally, I created a `callback` function based on the GDBUS signal
based on `handle-request-confirmation` which looks like this:

    g_signal_connect(agent, "handle-request-confirmation",
                 G_CALLBACK (on_request_confirmation), NULL);
> The above code is in main()

    int on_request_confirmation(CustomOrgBluezAgent1 *agent,
        GDBusMethodInvocation *invocation, gchar* path,
        guint32 passkey, gpointer userdata) {
            g_print("Hello WORLD!");
            set_trusted(path);
            return TRUE;
    }
> This is the actual callback function

My problem is that I am not able to have my Agent1 interface register
as a default agent. I tried invoking the `AgentManager1` in
`org.bluez` with `RegisterAgent` and `RequestDefaultAgent`, but it
doesn't seem to use the newly created service and I assume it uses a
separate one within the `org.bluez` service.

I have a couple of questions:
- Is this the proper way to implement a custom Agent1?
- How do I make it the default agent?
- How can I check what Agent is currently the default? It doesn't
appear anywhere in `d-feet` (the GUI d-bus explorer). I noticed the
agent implemented in Ubuntu though obex, but this is in Session (when
the bluetooth settings app is opened, the service appears in the
Session Bus):[4]

  [1]: https://medium.com/@matteodipirro/developing-a-bluetooth-agent-in-qt-c-with-bluez-and-d-bus-part-1-ee35d614ba72
  [2]: https://www.freedesktop.org/software/gstreamer-sdk/data/docs/latest/gio/ch30s05.html
  [3]: https://i.stack.imgur.com/pe0Li.png
  [4]: https://i.stack.imgur.com/UQ8na.png

Many thanks and regards,
Mihai