Simple PHP form: Attachment to email (code golf)

Just for fun I thought I’d knock it up. It ended up being trickier than I thought because I went in not fully understanding how the boundary part works, eventually I worked out that the starting and ending ‘–‘ were significant and off it went.

<?php
    if(isset($_POST['submit']))
    {
        //The form has been submitted, prep a nice thank you message
        $output="<h1>Thanks for your file and message!</h1>";
        //Set the form flag to no display (cheap way!)
        $flags="style="display:none;"";

        //Deal with the email
        $to = '[email protected]';
        $subject="a file for you";

        $message = strip_tags($_POST['message']);
        $attachment = chunk_split(base64_encode(file_get_contents($_FILES['file']['tmp_name'])));
        $filename = $_FILES['file']['name'];

        $boundary =md5(date('r', time())); 

        $headers = "From: [email protected]\r\nReply-To: [email protected]";
        $headers .= "\r\nMIME-Version: 1.0\r\nContent-Type: multipart/mixed; boundary=\"_1_$boundary\"";

        $message="This is a multi-part message in MIME format.

--_1_$boundary
Content-Type: multipart/alternative; boundary=\"_2_$boundary\"

--_2_$boundary
Content-Type: text/plain; charset=\"iso-8859-1\"
Content-Transfer-Encoding: 7bit

$message

--_2_$boundary--
--_1_$boundary
Content-Type: application/octet-stream; name=\"$filename\" 
Content-Transfer-Encoding: base64 
Content-Disposition: attachment 

$attachment
--_1_$boundary--";

        mail($to, $subject, $message, $headers);
    }
?>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>MailFile</title>
</head>

<body>

<?php echo $output; ?>

<form enctype="multipart/form-data" action="<?php echo $_SERVER['PHP_SELF'];?>" method="post" <?php echo $flags;?>>
<p><label for="message">Message</label> <textarea name="message" id="message" cols="20" rows="8"></textarea></p>
<p><label for="file">File</label> <input type="file" name="file" id="file"></p>
<p><input type="submit" name="submit" id="submit" value="send"></p>
</form>
</body>
</html>

Very barebones really, and obviously the using inline CSS to hide the form is a bit cheap and you’d almost certainly want a bit more feedback to the user! Also, I’d probably spend a bit more time working out what the actual Content-Type for the file is, rather than cheating and using application/octet-stream but that part is quite as interesting.

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