KaiOS APIs

Sat, 08 May 2021 10:20:26 +0200

You might have already heard that #WhatsApp uses some undocumented APIs that are built into the #KaiOS system. These APIs are powered by the api-daemon, a daemon which lies at a lower level than Gecko. In this post, I will explain what I have found out about this daemon.

The api-daemon is written in #Rust, and provides several “services”. Each service has two parts, the JS client and the Rust library. The Rust library is linked into the api-daemon executable. The JS clients are accessible via HTTP at http://127.0.0.1:8081/api/v1//

We can now use these APIs as described in https://developer.stage.kaiostech.com/docs/sfp-3.0/09.migration-from-2.5/next-new-apis/daemon-api/telephony/daemon-api-telephony/, except that we will need to replace localhost with localhost:8081. Note that the documentation is for KaiOS 3.0, but on 2.5 only the telephony, libsignal (for WhatsApp) and tcpsocket services are available. You can also look at the api-daemon source code, which is also only for KaiOS 3.0.

First, we need to set up a `sess` variable that stores the api-daemon session:

var sess = new lib_session.Session();

Then, we write some handlers that get called when the session connects/disconnects:

function onsessionconnected(){
  lib_telephony.TelephonyService.get(sess).then(function(service){
    /* handle session connect */
  });
}
function onsessiondisconnected(){
  /* handle session disconnect */
}

And after that we try connecting.

sess.open('websocket', 'localhost:8081', 'secrettoken',
  {onsessionconnected, onsessiondisconnected}, true);

Here is the final code:

daemon-test.js

window.onerror = function(e){
  // Error handling
  alert(e);
}

var sess = new lib_session.Session();
var el_state = document.getElementById('callstate');
var toggleCallState = null;

function callStateChangeCallback(state){
  el_state.textContent = state;
}

// Set up session callbacks
var onsessionconnected = function(){
  alert('Session connected');
  // Get an instance of the telephony manager
  lib_telephony.TelephonyService.get(sess).then(function(manager){
    alert('Got Telephony manager');
    try {
      // Show the call state
      manager.callState.then(function(state){
        el_state.textContent = 'Call state: ' + state;
      });

      // Show it again if it changes
      manager.addEventListener(manager.CALLSTATE_CHANGE_EVENT, function(state){
          el_state.textContent = 'Call state: ' + state;
      });

      toggleCallState = function(){
        // Get the call state
        manager.callState.then(function(state){
          // Set the call state
          manager.callState = state ? 0 : 1;
          alert(state ? 'Idle' : 'Calling');
        });
      }
    } catch(e) {
      alert(e);
    }
  }).catch(function(e){
    alert('Failed to get Telephony manager: ' + JSON.stringify(e));
    toggleCallState = null;
  });
}
var onsessiondisconnected = function(){
  alert('Disconnected');
  toggleCallState = null;
}

// Initialize the api-daemon session
sess.open('websocket', 'localhost:8081', 'secrettoken',
  {onsessionconnected, onsessiondisconnected}, true);

window.addEventListener('keydown', function(e){
  if(e.key == 'Call'){
    // Toggle the state if 'Call' is pressed and the session is ready
    if(typeof toggleCallState === 'function') toggleCallState();
  }
});

There is a lot more to this. I will also make a wiki page, and some more posts about things such as the updater-daemon and remote services.

More tags: #ApiDaemon

KaiOS — affe-null

KaiOS APIs

First, we need to set up a sess variable that stores the api-daemon session:

Then, we write some handlers that get called when the session connects/disconnects:

And after that we try connecting.

Here is the final code:

First, we need to set up a `sess` variable that stores the api-daemon session: