Email Piping - Read Attachment (.txt file) - php

Question

I'm using email piping to save data sent by an end user through email; however, one requirement is that the user sends a text file with additional information.
Therefore, I need the email piping script to get the attachment, and read it. It's a simple text (.txt) document, base64 encoding, example:
Content-Type: text/plain; charset=UTF-8
Content-ID: <text_doc>
Content-Location: text_doc.txt
Content-Transfer-Encoding: BASE64
This is my Email Piping script. The email passes through fine, I just need to get the attachment.
<?php
chdir(dirname(__FILE__));
$fd = fopen("php://stdin", "r");
$email = "";
while (!feof($fd)) {
$email .= fread($fd, 1024);
}
fclose($fd);
if(strlen($email)<1) {
die();
}
// handle email
$lines = explode("\n", $email);
// empty vars
$from = "";
$to="";
$subject = "";
$headers = "";
$message = "";
$splittingheaders = true;
for ($i=0; $i < count($lines); $i++) {
if ($splittingheaders) {
// this is a header
$headers .= $lines[$i]."\n";
// look out for special headers
if (preg_match("/^Subject: (.*)/", $lines[$i], $matches)) {
$subject = $matches[1];
}
if (preg_match("/^From: (.*)/", $lines[$i], $matches)) {
$from = $matches[1];
}
if (preg_match("/^To: (.*)/", $lines[$i], $matches)) {
$to = $matches[1];
}
} else {
// not a header, but message
$message .= $lines[$i]."\n";
}
if (trim($lines[$i])=="") {
// empty line, header section has ended
$splittingheaders = false;
}
}