obtaining local ip, through webRTC is a security vulnerability. Some browsers have restrictions that support webRTC, but cannot get ip.

self-question and answer:

I found that browsers using UC browser kernels such as Xiaomi and Huawei, as well as UC browsers, do not support WEBRTC technology, and these browsers may get stuck when reading webRTC code, resulting in the following code can not be executed, which is very cheating.

my solution:

write a timer for 3 seconds. If you haven't got the user's ip, you can declare a failure (3 seconds is already a long time, so you can reduce it as appropriate), then you can only give a null value.

Let's first judge whether the next branch does not support it. Is there this variable under Window? if so, try catch it. No null value is given directly

if (window.RTCPeerConnection || window.webkitRTCPeerConnection || window.mozRTCPeerConnection) {
    var Rtc = window.RTCPeerConnection || window.webkitRTCPeerConnection || window.mozRTCPeerConnection;
    try {
        var nrtc = new Rtc({
            iceServers: []
        });
        nrtc.createDataChannel('', {
            reliable: !1
        });
    } catch (e) {
        infoObj['ip'] = '0.0.0.0';
        return infoObj;
    }

    var e = false;
    nrtc.onicecandidate = function(Rtc) {
        ...
    };

    nrtc.createOffer(function(a) {
        nrtc.setLocalDescription(a, that.F(), that.F());
    }, that.F());

    infoObj.ip = window.currentIp || '0.0.0.0';

    return infoObj;
} else {
    infoObj['ip'] = '0.0.0.0';

    return infoObj;
}