<?php
session_start();
$_SESSION['flag'] = 0;
$myfile = fopen("passwd","r") or die("Unable to open file!");
$passwd = fgets($myfile);
if(empty($_POST['pass'])){
  echo "不能为空，重新输入";
  $page = "login.html";
}else{
  $pass = $_POST['pass'];
  $passwd = test_input($passwd);
  $pass = test_input($pass);
  if($pass == $passwd){
    echo "口令正确，允许访问";
    $page = "list_all.php";
    $_SESSION['flag'] = 1;
    $_SESSION['time'] = time(); //当前秒数
  }else{
    echo "口令错误，重新输入";
    $page = "login.html";
  }
}

function test_input($date){
  $date = trim($date);
  $date = stripcslashes($date);
  $date = htmlspecialchars($date);
  return $date;
}
?>
  <a href="<?php echo $page;?>" rel="external nofollow" >点此跳转</a>

<?php
session_start();
if($_SESSION['flag'] == 1){
  if(time() - $_SESSION['time'] > 600){
    echo "登陆超时";
    echo '<a href="login.html" rel="external nofollow" rel="external nofollow" >点此登陆</a>';
    session_destroy();
    exit();
  }else{
  $_SESSION['time'] = time();
  }
}else{
  echo "未登陆，无权访问！";
  echo '<a href="login.html" rel="external nofollow" rel="external nofollow" >点此登陆</a>';
  session_destroy();
  exit();
}
?>