auth.php

<?php
    $licence = substr(base64_decode($_POST["licence"]), 0, -8);
    $hwid = substr(base64_decode($_POST["hwid"]), 0, -8);

    $db_user = "u155468569_admin";
    $db_name = "u155468569_kappa";
    $db_host = "mysql.hostinger.co.uk";
    $db_pass = "11233240";

    if (isset($licence) == false) {
        echo("bad");
        return;
    }
    if (isBadInput($licence) or isBadInput($hwid)) {
        echo("bad");
        return;
    }
    
    if (checkAuth()) {
        echo("ok");
    } else {
        echo("bad");
    }
    return;

    function checkAuth() {
        if (checkLic()) {
            if (needNewHWID()) {
                setHwid();
                return true;
            }
            if (checkHwid()) {
                return true;
            }
        }
        return false;
    }

    function checkLic() {
        // Create connection
        $conn = new mysqli($db_name, $db_user, $db_pass, $db_name);

        // Check connection
        if ($conn->connect_error) {
            die("Connection failed: " . $conn->connect_error);
        }

        if ($verify = $conn->prepare("SELECT * FROM users WHERE licence=?")) {
            $verify->bind_param('s', $licence);
            $verify->execute();

            $result = $verify->get_result();

            if ($result->num_rows > 0) {
                while ($row = $result->fetch_assoc()) {
                    if ($row["licence"] == $licence) {
                        return true;
                    }
                }
            }
        }

        $conn->close();
        return false;
    }
    function checkHwid() {
        // Create connection
        $conn = new mysqli($db_name, $db_user, $db_pass, $db_name);

        // Check connection
        if ($conn->connect_error) {
            die("Connection failed: " . $conn->connect_error);
        }

        if ($verify = $conn->prepare("SELECT hwid FROM users WHERE hwid=?")) {

            $verify->bind_param('s', $hwid);
            $verify->execute();

            $result = $verify->get_result();

            if ($result->num_rows > 0) {
                while ($row = $result->fetch_assoc()) {
                    if ($row["hwid"] == $hwid) {
                        return true;
                    }
                }
            }
        }
        $conn->close();
        return false;
    }
    function setHWID() {
        // Create connection
        $conn = new mysqli($db_name, $db_user, $db_pass, $db_name);

        // Check connection
        if ($conn->connect_error) {
            die("Connection failed: " . $conn->connect_error);
        }
        if ($verify = $conn->prepare("UPDATE users SET hwid = ? WHERE licence=?")) {
            if (isset($verify) == false) {
                $conn->close();
                return false;
            }
        
            $verify->bind_param('ss', $hwid, $licence);
            $verify->execute();
        }

        $conn->close();
    }

    function needNewHWID() {
        // Create connection
        $conn = new mysqli($db_name, $db_user, $db_pass, $db_name);

        // Check connection
        if ($conn->connect_error) {
            die("Connection failed: " . $conn->connect_error);
        }

        if ($verify = $conn->prepare("SELECT hwid FROM users WHERE licence=?")) {
            $verify->bind_param('s', $licence);
            $verify->execute();

            $result = $verify->get_result();

            if ($result->num_rows > 0) {
                while ($row = $result->fetch_assoc()) {
                    if ($row["hwid"] == "notset") {
                        return true;
                    }
                }
            }
        }

        $conn->close();
        return false;
    }

    function isBadInput() {
        if (strlen($input) > 30) {
            return true;
        }
        if (strpos(strtolower($input), 'where') !== false or 
            strpos(strtolower($input), 'insert into') !== false or 
            strpos(strtolower($input), 'from') !== false or 
            strpos(strtolower($input), 'update') !== false or 
            strpos(strtolower($input), 'set') !== false) {
                return true;
        } 
    }
?>