validation.php

<?php

$username = "jas";
$password = "123";
$checkusername = $_POST['t1'];
$checkpassword = $_POST['t2'];


    if($checkusername == "$username" && $checkpassword == "$password"){
        ?>
        <script>
        window.location="log.php?id=1&user=<?php echo $username; ?> &pass=<?php echo $password;?>";
        </script>
        <?php

    } else {
        ?>
        <script>
        window.location="log.php?id=2";
        </script>
        <?php
}

?>