PHP教程(二十二) E-mail 注入
<html>
<body>
<?php
if (isset($_REQUEST['email']))
//if "email" is filled out, send email
{
//send email
$email = $_REQUEST['email'] ;
$subject = $_REQUEST['subject'] ;
$message = $_REQUEST['message'] ;
mail("someone@example.com", "Subject: $subject",
$message, "From: $email" );
echo "Thank you for using our mail form";
}
else
//if "email" is not filled out, display the form
{
echo "<form method='post' action='mailform.php'>
Email: <input name='email' type='text' /><br />
Subject: <input name='subject' type='text' /><br />
Message:<br />
<textarea name='message' rows='15' cols='40'>
</textarea><br />
<input type='submit' />
</form>";
}
?>
</body>
</html>以上代码存在的问题是，未经授权的用户可通过输入表单在邮件头部插入数据。
someone@example.com%0ACc:person2@example.com
%0ABcc:person3@example.com,person3@example.com,
anotherperson4@example.com,person5@example.com
%0ABTo:person6@example.com与往常一样，mail() 函数把上面的文本放入邮件头部，那么现在头部有了额外的 Cc:, Bcc: 以及 To: 字段。当用户点击提交按钮时，这封 e-mail 会被发送到上面所有的地址！
PHP 防止 E-mail 注入
防止 e-mail 注入的最好方法是对输入进行验证。
下面的代码与上一节类似，不过我们已经增加了检测表单中 email 字段的输入验证程序：
if (isset($_REQUEST['email']))
{//if "email" is filled out, proceed
//check if the email address is invalid
$mailcheck = spamcheck($_REQUEST['email']);
if ($mailcheck==FALSE)
{
echo "Invalid input";
}
else
{//send email
$email = $_REQUEST['email'] ;
$subject = $_REQUEST['subject'] ;
$message = $_REQUEST['message'] ;
mail("someone@example.com", "Subject: $subject",
$message, "From: $email" );
echo "Thank you for using our mail form";
}
}
else
{//if "email" is not filled out, display the form
echo "<form method='post' action='mailform.php'>
Email: <input name='email' type='text' /><br />
Subject: <input name='subject' type='text' /><br />
Message:<br />
<textarea name='message' rows='15' cols='40'>
</textarea><br />
<input type='submit' />
</form>";
}
?>
</body>
</html>在上面的代码中，我们使用了 PHP 过滤器来对输入进行验证：
?FILTER_SANITIZE_EMAIL 从字符串中删除电子邮件的非法字符
?FILTER_VALIDATE_EMAIL 验证电子邮件地址
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