/includes/filter-wrapper.php

<?php

/**
 * Check for the existence some of the PHP filters
 * If they don't exist recreate them so we can use them
 */
if (!defined('FILTER_VALIDATE_BOOLEAN')) define('FILTER_VALIDATE_BOOLEAN', 'FILTER_VALIDATE_BOOLEAN');
if (!defined('FILTER_VALIDATE_EMAIL')) define('FILTER_VALIDATE_EMAIL', 'FILTER_VALIDATE_EMAIL');
if (!defined('FILTER_VALIDATE_FLOAT')) define('FILTER_VALIDATE_FLOAT', 'FILTER_VALIDATE_FLOAT');
if (!defined('FILTER_VALIDATE_INT')) define('FILTER_VALIDATE_INT', 'FILTER_VALIDATE_INT');
if (!defined('FILTER_VALIDATE_REGEXP')) define('FILTER_VALIDATE_REGEXP', 'FILTER_VALIDATE_REGEXP');
if (!defined('FILTER_VALIDATE_URL')) define('FILTER_VALIDATE_URL', 'FILTER_VALIDATE_URL');

if (!defined('FILTER_SANITIZE_EMAIL')) define('FILTER_SANITIZE_EMAIL', 'FILTER_SANITIZE_EMAIL');
if (!defined('FILTER_SANITIZE_NUMBER_FLOAT')) define('FILTER_SANITIZE_NUMBER_FLOAT', 'FILTER_SANITIZE_NUMBER_FLOAT');
  if (!defined('FILTER_FLAG_ALLOW_FRACTION')) define('FILTER_FLAG_ALLOW_FRACTION', 'FILTER_FLAG_ALLOW_FRACTION');
if (!defined('FILTER_SANITIZE_NUMBER_INT')) define('FILTER_SANITIZE_NUMBER_INT', 'FILTER_SANITIZE_NUMBER_INT');
if (!defined('FILTER_SANITIZE_STRING')) define('FILTER_SANITIZE_STRING', 'FILTER_SANITIZE_STRING');
if (!defined('FILTER_SANITIZE_SPECIAL_CHARS')) define('FILTER_SANITIZE_SPECIAL_CHARS', 'FILTER_SANITIZE_SPECIAL_CHARS');
if (!defined('FILTER_SANITIZE_URL')) define('FILTER_SANITIZE_URL', 'FILTER_SANITIZE_URL');
if (!defined('FILTER_UNSAFE_RAW')) define('FILTER_UNSAFE_RAW', 'FILTER_UNSAFE_RAW');

if (!defined('FILTER_DEFAULT')) define('FILTER_DEFAULT', FILTER_UNSAFE_RAW);

if (!defined('INPUT_GET')) define('INPUT_GET', 'INPUT_GET');
if (!defined('INPUT_POST')) define('INPUT_POST', 'INPUT_POST');
if (!defined('INPUT_COOKIE')) define('INPUT_COOKIE', 'INPUT_COOKIE');
if (!defined('INPUT_SERVER')) define('INPUT_SERVER', 'INPUT_SERVER');
if (!defined('INPUT_ENV')) define('INPUT_ENV', 'INPUT_ENV');

/**
 * Check if the filter_input and filter_var functions exist
 * If they do not exist create them
 */
if (!function_exists('filter_input')) {
  function filter_input($type, $variable_name, $filter = FILTER_DEFAULT, $options = array()) {
    return filter_input_wrapper($type, $variable_name, $filter, $options);
  }
}

if (!function_exists('filter_var')) {
  function filter_var($variable, $filter = FILTER_DEFAULT, $options = array()) {
    return filter_var_wrapper($variable, $filter, $options);
  }
}

/**
 * Mock replacement for filter_input
 * Sends values to filter_var for filtering
 */
function filter_input_wrapper ($type, $variable_name, $filter = FILTER_DEFAULT, $options = array()) {
  $input = $_GET;

  switch ($type) {
    case 'INPUT_POST' :
      $input = $_POST;
      break;
    case 'INPUT_COOKIE' :
      $input = $_COOKIE;
      break;
    case 'INPUT_SERVER' :
      $input = $_SERVER;
      break;
    case 'INPUT_ENV' :
      $input = $_ENV;
      break;
  }

  return isset($input[$variable_name]) ? filter_var_wrapper($input[$variable_name], $filter, $options) : null;
}

/**
 *  Mock replacement for filter_var
 *  Uses built in PHP functions or regular expressions to perform similar actions on the data
 */
function filter_var_wrapper ($variable, $filter = FILTER_DEFAULT, $options = array()) {
  switch ($filter) {
    case FILTER_SANITIZE_EMAIL :
      return preg_replace(">[^a-z0-9\!\#\$\%\&\'\*\+\-\/\=\?\^\_\`\{\|\}\~\@\.\[\]]>iu", '', $variable);
      break;

    case FILTER_SANITIZE_NUMBER_FLOAT :
      $decimal = ($options == FILTER_FLAG_ALLOW_FRACTION) ? '\.' : '';
      return preg_replace('@[^\d\+\-' . $decimal . ']@', '', $variable);
      break;

    case FILTER_SANITIZE_NUMBER_INT :
      return preg_replace('@[^\d\+\-]@', '', $variable);
      break;

    case FILTER_SANITIZE_SPECIAL_CHARS :
      return htmlspecialchars($s, ENT_QUOTES, 'UTF-8', false);
      break;

    case FILTER_SANITIZE_STRING :
      return strip_tags($variable);
      break;

    case FILTER_SANITIZE_URL :
      return preg_replace(">[^a-z0-9\$\-\_\.\+\!\*\'\(\)\,\{\}\|\\\\^\~\[\]\`\<\>\#\%\"\;\/\?\:\@\&\=\.]>iu", '', $variable);
      break;

    case FILTER_VALIDATE_BOOLEAN :
      $input = (is_string($variable)) ? trim(strtolower($variable)) : $variable;

      if ($input === 1 || $input === true)
        return true;

      return (bool)in_array($input, array('1', 'true', 'on', 'yes'));
      break;

    case FILTER_VALIDATE_EMAIL :
      // From HTML5 spec: http://html5.org/tools/web-apps-tracker?from=6883&to=6884o
      // And: http://blog.gerv.net/2011/05/html5_email_address_regexp/
      return (bool)preg_match(">^[a-zA-Z0-9.!#$%&'*+/=?\^_`{|}~-]+@[a-zA-Z0-9-]+(?:\.[a-zA-Z0-9-]+)*$>", $variable);
      break;

    case FILTER_VALIDATE_FLOAT :
      return (bool)is_numeric($variable);
      break;

    case FILTER_VALIDATE_INT :
      if (!is_numeric($variable) || floor($variable) != $variable)
        return false;

      $min_range = (isset($options['options']['min_range'])) ? $options['options']['min_range'] : null;

      if ($min_range !== null && $variable < $min_range)
        return false;

      $max_range = (isset($options['options']['max_range'])) ? $options['options']['max_range'] : null;

      if ($max_range !== null && $variable > $max_range)
        return false;

      return true;
      break;

    case FILTER_VALIDATE_REGEXP :
      return (bool)preg_match($options['options']['regexp'], $variable);
      break;

    case FILTER_VALIDATE_URL :
      return (bool)preg_match('@^[a-z][\w-]+:(?:/{1,3})?[^\s()<>]+(\.[^\s()<>]+(/[^\s]*)?)?$@iu', $variable);
      break;

    case FILTER_UNSAFE_RAW :
    case FILTER_DEFAULT :
    default:
      return $variable;
  }
}