use drupal_http_request for file request

I wanted to test this out on an FTP site so I went to an old account on DreamHost.

When I enabled it and visited the themes tab I get this warning:

    * warning: simplexml_load_file() [function.simplexml-load-file]: URL file-access is disabled in the server configuration in d6/sites/all/modules/plugin_manager/plugin_manager.module on line 188.
    * warning: simplexml_load_file(http://updates.drupal.org/release-history/project-list/all) [function.simplexml-load-file]: failed to open stream: no suitable wrapper could be found in d6/sites/all/modules/plugin_manager/plugin_manager.module on line 188.
    * warning: simplexml_load_file() [function.simplexml-load-file]: I/O warning : failed to load external entity "http://updates.drupal.org/release-history/project-list/all" in d6/sites/all/modules/plugin_manager/plugin_manager.module on line 188.

This doesn't work because allow_url_fopen is disabled.

I believe that the general way around this is to use drupal_http_request.

I played with this for a little and believe that I've found the answer (see attached). If you can test it out and it works in your environment, then perhaps this will work more generally as well.