Detect behind VPN in android

Question

How to detect programatically if traffic is going through VPN without using intent to connect to VPNService. Is there some system call?

Answer 1

It is possible to check it in Android API 21 an higher, but it seems doesn't work (on nexus 5 @ 5.0.1, nexus 7 @ 5.0.2). Why its not working?

Snippet of new API for check it (and all traffic is routed by vpn if connected):

@Inject
boolean checkVPN(ConnectivityManager connMgr) {
    //don't know why always returns null:
    NetworkInfo networkInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_VPN);

    boolean isVpnConn = networkInfo == null ? false : networkInfo.isConnected();
    return isVpnConn;
}