controlling wpa_supplicant using node.js

Question

I would like to control wpa_supplicant using a node.js module. Most importantly I want to be able to detect connection failures so I can write a program that can act upon them.

So far setting up a wireless connection using wpa_supplicant with terminal commands has succeeded. I have tried to access the wlan0 interface using the dbus-native module but have been unable to access the interface.

I am also open to using other existing node modules or write my own if I can be pointed in the right direction.

Would anyone be able to help me advance here?

Code I have tried so far:

var dbus = require('dbus-native');
var util = require('util');

var bus = dbus.systemBus();
var wpas = bus.getService('fi.w1.wpa_supplicant1');

var wpai = wpas.getInterface('/fi/w1/wpa_supplicant1'
    , 'fi.w1.wpa_supplicant1', function (err, iface) {
        //console.log(err, iface);

        iface.on('PropertiesChanged', function(dict) {
            console.log('interface properties have changed!');
            console.log(dict);
        });

        iface.on('InterfaceAdded', function(path, dict) {
            console.log('interface has been added!');
            console.log(path, dict);
        });

        iface.on('InterfaceRemoved', function(path) {
            console.log('interface has been removed!');
            console.log(path);
        });

        // wpa_supplicant denies knowledge of the interface
        iface.GetInterface('wlan0', function (err, iface2) {
            console.log( arguments );
            console.log(err, iface2);
        });

        //error couldn't grab interface
        iface.CreateInterface([
            ['Ifname',
                ['s', 'wlan0']
            ]
        ], function (err, iface3){
            console.log(err, iface3);
        });

        //error couldn't grab interface
        iface.CreateInterface([
            ['Ifname',
                ['s', 'wlan0']
            ],
            ['Driver',
                ['s', 'nl80211']
            ],
            ['ConfigFile',
                ['s', '~/etc/wpa_supplicant/wpa_supplicant.conf']
            ]
        ], function (err, iface3){
            console.log(err, iface3);
        });

    });

Update 1:

I used the DBus properties api to investigate the Interfaces properties and discovered that the the property itself was null.

wpas.getInterface('/fi/w1/wpa_supplicant1', 'org.freedesktop.DBus.Properties', function(err, device) {
                device.GetAll('fi.w1.wpa_supplicant1', function(err, prop) {
                    var props = arrToMap(prop);
                    console.log(err,props);
                });
            });

function arrToMap(arr) {
    var output = {};
    for (var i = 0; i < arr.length; i++) {
        output[arr[i][0]] = arr[i][1][1][0];
    }
    return output;
}

My only conclusion is that the wpa_supplicant never registers any new interfaces with the dbus.

(I have ensured that I set up my wlan0 using wpa_supplicant using terminal commands)

Update 2:

I have continuously tried to figure out why the following part of my code keeps giving me the error:

[ 'wpa_supplicant couldn\'t grab this interface.' ]

  iface.CreateInterface([
            ['Ifname',
                ['s', 'wlan0']
            ]
        ], function (err, iface3){
            console.log(err, iface3);
        });

Answer 1

Not sure about how NodeJs handles this but can not create an interface again and again on the wpa supplicant. Once you have registered an interface on the wpa, it throws error upon calling "create_interface" again.

To clarify,"Create interface" is a functionality that is used only the first time that you use the interface. For example, I have worked with wpa supplicant in python, and the python wpa supplicant API has two functionalities for this, "create_interface" and "get_interface".

I have been using this on an IoT device, so, sharing the Python code:

try:
    wpa.create_interface('wlp2s0')
except:
    wpa.get_interface('wlp2s0')

where 'wlp2s0' is the interface name.