Using file_get_contents() to fetch the contents of a file is quite a common practice. This might be just to get the contents of a text file or to get the ImageCache module in Drupal to pre-cache images. The file_get_contents() function can get a local or remote file and is usually run like this.
$data = file_get_contents($url);
However, when trying to use this function to communicate with an authenticated server you will see the following error appearing.