PHP 安全的电子邮件
PHP 安全的电子邮件PHP E-mailPHP Error在上一节中的 PHP e-mail 脚本中，存在着一个漏洞。PHP E-mail 注入首先，请看上一节中的 PHP 代码：<html><body><?phpif (isset($_REQUEST['email']))//if "email" is filled out, send email { //send email $email = $_REQUEST['email'] ; $subject = $_REQUEST['subject'] ; $message = $_REQUEST['message'] ; mail("[email protected]", "Subject: $subject", $message, "From: $email" ); echo "Thank you for using our mail form"; }else//if "email" is not filled out, display the form { echo "<form method='post' action='mailform.php'> Email: <input name='email' type='text' /><br /> Subject: <input name='subject' type='text' /><br /> Message:<br /> <textarea name='message' rows='15' cols='40'> </textarea><br /> <input type='submit' /> </form>"; }?></body></html>以上代码存在的问题是，未经授权的用户可通过输入表单在邮件头部插入数据。假如用户在表单中的输入框内加入这些文本，会出现什么情况呢？[email protected]%0ACc:[email protected]%0ABcc:[email protected],[email protected],[email protected],[email protected]%0ABTo:[email protected]与往常一样，mail() 函数把上面的文本放入邮件头部，那么现在头部有了额外的 Cc:, Bcc: 以及 To: 字段。当用户点击提交按钮时，这封 e-mail 会被发送到上面所有的地址！PHP 防止 E-mail 注入防止 e-mail 注入的最好方法是对输入进行验证。下面的代码与上一节类似，不过我们已经增加了检测表单中 email 字段的输入验证程序：<html><body><?phpfunction spamcheck($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("[email protected]", "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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