Get Remote IP Address in PHP

function getRemoteIPAddress() {
    $ip = $_SERVER['REMOTE_ADDR'];
    return $ip;
}

The above code will not work in case your client is behind proxy server. In that case use below function to get real IP address of client.

function getRealIPAddr()
{
    if (!empty($_SERVER['HTTP_CLIENT_IP']))   //check ip from share internet
    {
        $ip=$_SERVER['HTTP_CLIENT_IP'];
    }
    elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR']))   //to check ip is pass from proxy
    {
        $ip=$_SERVER['HTTP_X_FORWARDED_FOR'];
    }
    else
    {
        $ip=$_SERVER['REMOTE_ADDR'];
    }
    return $ip;
}

Base64 Encode and Decode String in PHP

function base64url_encode($plainText) {
    $base64 = base64_encode($plainText);
    $base64url = strtr($base64, '+/=', '-_,');
    return $base64url;
}
 
function base64url_decode($plainText) {
    $base64url = strtr($plainText, '-_,', '+/=');
    $base64 = base64_decode($base64url);
    return $base64;
}