Untitled

<?php
session_start();
$ulist = file_get_contents("/opt/ulist.txt");

?>
<html>
	<body>
		<?php
		if(isset($_POST['user']) && isset($_POST['pass'])){
			$user = $_POST['user'];
			$pass = $_POST['pass'];

			if(strpos($ulist, $user) !== false){
				if($user == "" && $pass == "") {
					$_SESSION['valid'] = true;
				}
				else {
					echo 'Wrong username or password.';
				}
			} else
			{
				echo 'Wrong username or password..';
			}
		}
		if(!$_SESSION['valid']){
			echo '
		<form action="index.php" method="post">
			<input type="text" name="user" /><br />
			<input type="password" name="pass" /><br />
			<input type="submit" value="Log in" />
		</form>';
		}
		?>
	</body>
</html>