A slightly saner interface for JangoMail Sync than the one they supply

jangomail-sync.php

<?php

/**
 * A slightly saner interface for JangoMail Sync than the one they supply
 *
 * This is a demonstration of how to produce a more security-aware interface for JangoMail's
 * web database synchronisation system. It is not guaranteed in any way and is not meant
 * to be seen as an example of best practice on any level. It does, however, demonstrate how
 * the flaws in that system can be worked around to build a reasonable JSON-based interface
 * when working with recent versions of PHP.
 *
 * See http://jystewart.net/process/2010/06/jangomail-lackadaisical-security-and-a-workaround/
 * for more.
 * 
 * @author  James Stewart <james@ketlai.co.uk>
 * @date    9th June 2010
 */

/**
 * Very crude way to handle errors
 */
function return_error($code_and_message) {
  header('HTTP/1.1 ' . $code_and_message);
  echo $code_and_message;
  exit;
}

/**
 * Do our basic mysql connection. In a function to make sure we only call it when we need it.
 */
function make_mysql_connection() {
  mysql_connect(DB_HOST, DB_USER, DB_PASSWORD);
}

/**
 * Make sure this is a real email address and give a 406 if not
 */
function check_email($address) {
  $email = filter_var($address, FILTER_VALIDATE_EMAIL);
  if (! $email) {
    return_error('406 Unacceptable');
  }
  return $email;
}

/**
 * Handle the 'massmail' request, returning a list of active email addresses
 *
 * @return String
 */
function retrieve_addresses() {
  $fields = array('name', 'email');
  $output = implode(',', $fields) . FIELDNAME_DELIMITER;

  make_mysql_connection();
  $query = "SELECT `name`, `email` FROM `email_subscribers` 
    WHERE `unsubscribed` = 0 AND bouncing = 0";
  $rs = mysql_query($query);
  while ($arr_row = mysql_fetch_row($rs)) {
    $output .= implode(COL_DELIMITER, $arr_row) . ROW_DELIMITER;
  }

  return $output;
}

/**
 * Handle the 'unsubscribe' action - mark our record for the address as unsubscribed
 *
 * @param stdClass
 * @return boolean | resource
 */
function handle_unsubscribe($params) {
  $email = check_email($params->email);

  make_mysql_connection();
  $query = sprintf("UPDATE `email_subscribers` SET `unsubscribed` = 1 WHERE `email` = '%s'", 
    mysql_real_escape_string($email));
  return mysql_query($query);
}

/**
 * Handle the 'bounce' action - mark our record for the address as bouncing
 *
 * @param stdClass
 * @return boolean | resource
 */
function handle_bounce($params) {
  $email = check_email($params->email);
  
  make_mysql_connection();
  $query = sprintf("UPDATE `email_subscribers` SET `bouncing` = 1 WHERE `email` = '%s'", 
    mysql_real_escape_string($email));
  return mysql_query($query);
}

/**
 * Handle the 'change' action - updating our email address for the user
 *
 * @param stdClass
 * @return boolean | resource
 */
function handle_change($params) {
  $new_email = check_email($params->new_email);
  $old_email = check_email($params->old_email);
  
  make_mysql_connection();

  $query = sprintf("UPDATE `email_subscribers` SET `email` = '%s' WHERE `email` = '%s'", 
    mysql_real_escape_string($new_email), mysql_real_escape_string($old_email));
  return mysql_query($query);
}

/* Rather crude way to check IP address is in range 209.173.141.193 - 209.173.141.255 */
preg_match('/(.+?)\.(\d+)$/', $_SERVER['REMOTE_ADDR'], $ip_parts);
if ($ip_parts[1] != '209.173.141' || $ip_parts[2] < 193 || $ip_parts[2] > 255) {
  return_error('403 Forbidden');
}
set_time_limit(1200);

define('USERNAME', 'sample');
define('PASSWORD', 'sample');

define('DB_HOST', 'localhost');
define('DB_USER', 'user');
define('DB_PASSWORD', 'password');

define('ROW_DELIMITER', 'WG0ROWWG0');
define('COL_DELIMITER', 'WG0COLWG0');
define('FIELDNAME_DELIMITER', '___ASDF---BREAK');
define('JANGO_EOF', 'WANGO-ENDOFDATASTREAM');

/* Process input */
$temp_params = $_POST;
function clean_params($param) {
  return str_replace('ABC-WANGOMAIL-ABC', chr(0), $param);
}
array_walk($temp_params, 'clean_params');

$params = array();
$strFieldNameDelimiter = '___ASDF---BREAK';
$params['action']      = $temp_params['action'];
$params['username']    = $temp_params['username'];
$params['password']    = $temp_params['password'];
$params['data'] = json_decode($temp_params['querystring']);

/* Authenticate */
if ($params['username'] != USERNAME || $params['password'] != PASSWORD) {
  return_error('403 Forbidden');
}

/* Dispatch actions */
switch ($params['action']) {
  # massmail actually means 'get list of users for mass mailing'
  case 'massmail':
    echo retrieve_addresses();
    break;
  case 'unsubscribe':
    if (handle_unsubscribe($params['data'])) {
      echo 'unsubscribe-sync-success';
    } else {
      echo 'unsubscribe-sync-failure';
    }
    break;
  case 'bounce':
    if (handle_bounce($params['data'])) {
      echo 'bounce-sync-success';
    } else {
      echo 'bounce-sync-failure';
    }
    break;
  case 'change':
    if (handle_change($params['data'])) {
      echo 'change-sync-success';
    } else {
      echo 'change-sync-failure';
    }
    break;
  case 'view':
  case 'click':
  case 'sent':
  case 'job':
  case 'action':
  case 'forward':
  case 'test':
    # We don't care about any of these in our system so pretend they worked
    echo $action . 'sync-success';
    break;
}