Colin McCann Dot Com

I’ll cut right to the awesome. This script runs every minute, checks an IMAP mailbox (that happens to be my work email), and detects if any new messages have been received. If so, all HTML and special characters are stripped (leaving plain ASCII text) from the message body, and truncated to 150 characters. Next, the script sends me a text message through Verizon’s email gateway “from” the original sender’s email address.

This is cool for a number of reasons. One, I don’t have to run an IMAP application on my phone; updates are pushed to me from an external source. Two, I don’t need a data plan to use it (although I may need to increase the number of texts I can receive without additional charges). Three, I can reply directly from my phone (although the message is received from a different address, depending on your carrier). Four, it’s got an accuracy of around one minute, and so far that has been more than adequate.

You need to create a web-writable file (chmod 755) called timestamp.txt in the same directory. I’ll include the cron script at the end of this post.

// filename: sms.php
$debug = false; // false = no output
$error = '';

// Define SMS parameters; your gateway may vary
$sms_to   = '4065551234@vtext.com';

// Define IMAP parameters
$imap_user = 'my.gmail.account';
$imap_pass = 'Secret-Password!';
$imap_host = '{imap.gmail.com:993/imap/ssl}INBOX';

// Define SMTP parameters
$smtp_host = 'smtp.mymailserver.com';
$smtp_port = '25';
$smtp_user = 'sms@mydomain.com'; // a valid user must exist
$smtp_pass = 'Another-Password!';

// Open a pointer to the mailbox
if ($debug) { $error = 'error: imap connection failed'; }
$imap = imap_open ($imap_host, $imap_user, $imap_pass) or die ($error);

// Quick exit
if (imap_num_msg ($imap) == 0) {
	imap_close ($imap);
	if ($debug) { $error = 'error: no messages in mailbox'; }
	die ($error);
}

// What was the last new message?
$old_timestamp = file_get_contents ('./timestamp.txt');

// Get last message
$msg_id = imap_num_msg ($imap);

// Gather IMAP message headers
$headers = imap_headerinfo ($imap, $msg_id);

// What's the timestamp on the most recent message?
$new_timestamp = $headers->udate;

// If it's the same message, get out of here.
if ($new_timestamp <= $old_timestamp) {
	imap_close ($imap);
	if ($debug) { $error = 'error: timestamp match'; }
	die ($error);
}

// Write timestamp of new message to external file
$handle = fopen ('timestamp.txt', 'w');
fwrite ($handle, $new_timestamp);
fclose ($handle);

// Let's look at that email we grabbed
$message = imap_get_message ($imap, $msg_id);

// Close IMAP Connection
imap_close ($imap);

// Okay, who's it from? Let's just do the email address...
// This needs cleaned up a bit; not all addresses include brackets.
$from = trim ($message['from']);
$b1 = strpos ($from, '<') + 1;
$b2 = strpos ($from, '>');
$from = substr ($from, $b1, ($b2 - $b1) );
// Here's an oddity -- gmail doesn't work. Go figure.
$from = str_replace ('gmail.com', 'g-mail.com', $from);

// And what's it say? Get rid of everything except alphanumerics and basic punctuation
$body = $message['body'];
$body = strip_tags ($body);
$body = preg_replace ('/[^A-Za-z0-9!-~]/', ' ', $body);
$body = preg_replace ('/\s\s+/', ' ', $body);

// Cut it off at 150 characters; seems to be the max for Verizon, anyway
$body = (strlen ($body) > 150) ? substr ($body, 0, 147).'...' : $body ;

// Set mail parameters; this sets the 'Return-Path' value
$param   = '-r '.$from;
$subject = '';
$headers = '';

// Send it off!
mail ($sms_to, $subject, $body, $headers, $param);

// IMAP message retrieval; returns a basic array
function imap_get_message ($imap_connection, $msg_no) {

	$header  = imap_header($imap_connection, $msg_no);
	$message = array();
	$message['subject'] = $header->subject;
	$message['from']    = $header->fromaddress;
	$message['to']      = $header->toaddress;
	$message['date']    = $header->date;

	$struct = imap_fetchstructure($imap_connection, $msg_no);
	@$parts = $struct->parts;
	$i = 0;

	if (!$parts) {
		$message['body'] = imap_body ($imap_connection, $msg_no);
	} else {
		$endwhile = false;

		$stack = array(); // Stack while parsing message
		$message['body'] = ''; // Content of message

		while (!$endwhile) {
			if (@!$parts[$i]) {
				if (count ($stack) > 0) {
					$parts = $stack[count ($stack) - 1]["p"];
					$i     = $stack[count ($stack) - 1]["i"] + 1;
					array_pop($stack);
				} else {
					$endwhile = true;
				}
			}

			if (!$endwhile) {
				// Create message part first (example '1.2.3')
				$partstring = '';
				foreach ($stack as $s) {
					$partstring .= ($s["i"]+1) . ".";
				}
				$partstring .= ($i+1);
				if (strtoupper ($parts[$i]->subtype) == "PLAIN") {
					$message['body'] .= imap_fetchbody ($imap_connection, $msg_no, $partstring); // Message
				}
			}

			if (@$parts[$i]->parts) {
				$stack[] = array("p" => $parts, "i" => $i);
				$parts = $parts[$i]->parts;
				$i = 0;
			} else {
				  $i++;
			}
		} // While loop
	}
	return $message;
}

Cron script:

# add to your crontab with 'crontab -e'
* * * * * /home/username/sms-gateway/sms.php