PHP E-mail 注入
首先，请看上一节中的 PHP 代码：
<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: $email" );
?echo "Thank you for using our mail form";
?}
else
//if "email" is not filled out, display the form
?{
?echo "<form method=‘post‘ action=‘mailform.php‘>
?Email: <input name=‘email‘ type=‘text‘ /><br />
?Subject: <input name=‘subject‘ type=‘text‘ /><br />
?Message:<br />
?<textarea name=‘message‘ rows=‘15‘ cols=‘40‘>
?</textarea><br />
?<input type=‘submit‘ />
?</form>";
?}
?>
</body>
</html>
以上代码存在的问题是，未经授权的用户可通过输入表单在邮件头部插入数据。
假如用户在表单中的输入框内加入这些文本，会出现什么情况呢？
someone@example.com%0ACc:person2@example.com
%0ABcc:person3@example.com,person3@example.com,
anotherperson4@example.com,person5@example.com
%0ABTo:bjrongjinhuiyin.com person6@example.com
与往常一样，mail() 函数把上面的融金汇银文本放入邮件头部，那么现在头部有了额外的 Cc:, Bcc: 以及 To: 字段。当用户点击提交按钮时，这封 e-mail 会被发送到上面所有的地址！
PHP 防止 E-mail 注入
防止 e-mail 注入的最好方法是对输入进行验证。
下面的代码与上一节类似，不过我们已经增加了配资平台检测表单中 email 字段的输入验证程序：
<html>
<body>
<?php
function spamcheck($field)
?{
?//filter_var() sanitizes the e-mail
?//address using FILTER_SANITIZE_EMAIL
?$field=filter_var($field, FILTER_SANITIZE_EMAIL);
?
?//filter_var() validates the e-mail
?//address using FILTER_VALIDATE_EMAIL
?if(filter_var($field, FILTER_VALIDATE_EMAIL))
???{
???return TRUE;
???}
?else
???{
???return FALSE;
???}
?}
if (isset($_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>
PHP 安全的电子邮件
原文地址：https://www.cnblogs.com/hshshs/p/8250708.html