Any way to get local IP address?

Add-ons Add-on Support
#1

With WebExtensions, is there any way to get the local IP address of the device? Previously I was using nsIDNSService to do it with legacy addons.

#2

AFAIK, not possible at the moment. The myIpAddress() was available in ProxyAutoConfig.cpp but it hasn’t been implemented due to being synchronous.

Do you want to get the local IP address in a WebExtension?
What would be the objective?

There is this one from @rob … but I get errors with it (RTCPeerConnection is not a constructor)

#3

My code snippet does work (in tabs and popups, but not in background pages - due to the following bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1398083#c2). If you see the RTCPeerConnection is not a constructor error, then you have most likely disabled WebRTC.

#4

I had not disabled it. I was testing it on Scratchpad.

#5

@rob, interesting solution. I am postingyour answer here so future readers don’t have to find your reply in the stackoverflow post, which will probably get longer and longer as time goes by:

// Example (using the function below).
getLocalIPs(function(ips) { // <!-- ips is an array of local IP addresses.
    document.body.textContent = 'Local IP addresses:\n ' + ips.join('\n ');
});

function getLocalIPs(callback) {
    var ips = [];

    var RTCPeerConnection = window.RTCPeerConnection ||
        window.webkitRTCPeerConnection || window.mozRTCPeerConnection;

    var pc = new RTCPeerConnection({
        // Don't specify any stun/turn servers, otherwise you will
        // also find your public IP addresses.
        iceServers: []
    });
    // Add a media line, this is needed to activate candidate gathering.
    pc.createDataChannel('');
    
    // onicecandidate is triggered whenever a candidate has been found.
    pc.onicecandidate = function(e) {
        if (!e.candidate) { // Candidate gathering completed.
            pc.close();
            callback(ips);
            return;
        }
        var ip = /^candidate:.+ (\S+) \d+ typ/.exec(e.candidate.candidate)[1];
        if (ips.indexOf(ip) == -1) // avoid duplicate entries (tcp/udp)
            ips.push(ip);
    };
    pc.createOffer(function(sdp) {
        pc.setLocalDescription(sdp);
    }, function onerror() {});
}

<body style="white-space:pre"> IP addresses will be printed here... </body>