Отправка файла с POST-запросом через Drupal API

/**
 * Sends file to service.
 *
 * @param $path
 */
function fileUpload($path) {
  $params = array(
    // Указываем необходимые данные для передачи с запросом.
    'data' => '123',
  );
 
  $boundary = md5(uniqid());
  $post_data = array(
    'name' => basename($path),
    'file' => $path,
  );
 
  $options = array(
    'method' => 'POST',
    'data' => multipartEncode($boundary, $post_data),
    'headers' => array('Content-Type' => "multipart/form-data; boundary=$boundary"),
    'timeout' => 30,
  );
 
  $response = drupal_http_request('http://path/to/service' . '?' . drupal_http_build_query($params), $options);
 
  return $response;
}

/**
 * Processes data for HTTP request.
 *
 * @param $boundary
 * @param $params
 */
function multipartEncode($boundary, $params){
  $output = "";
 
  foreach ($params as $key => $value){
    $output .= "--$boundary\r\n";
    if ($key == 'file'){
      $output .= multipartEncFile($value);
    } else {
      $output .= multipartEncText($key, $value);
    }
  }
  $output .="--$boundary--";
 
  return $output;
}
 
/**
 * Encodes text for HTTP request.
 *
 * @param $name
 * @param $value
 */
function multipartEncText($name, $value){
  return "Content-Disposition: form-data; name=\"$name\"\r\n\r\n$value\r\n";
}
 
/**
 * Encodes file data for HTTP request.
 *
 * @param $path
 */
function multipartEncFile($path){
  if (substr($path, 0, 1) == "@") {
    $path = substr($path, 1);
  }
  $filename = basename($path);
  $mimetype = "application/octet-stream";
  $data = "Content-Disposition: form-data; name=\"file\"; filename=\"$filename\"\r\n";
  $data .= "Content-Transfer-Encoding: binary\r\n";
  $data .= "Content-Type: $mimetype\r\n\r\n";
  $data .= file_get_contents($path) . "\r\n";
 
  return $data;
}