Checks whether the server is capable of issuing HTTP requests.
The function sets the drupal_http_request_fail system variable to TRUE if drupal_http_request() does not work and then the system status report page will contain an error.
TRUE if this installation can issue HTTP requests.
function system_check_http_request() {
// Try to get the content of the front page via drupal_http_request().
$result = drupal_http_request(url('', array(
'absolute' => TRUE,
)), array(
'max_redirects' => 0,
));
// We only care that we get a http response - this means that Drupal
// can make a http request.
$works = isset($result->code) && $result->code >= 100 && $result->code < 600;
variable_set('drupal_http_request_fails', !$works);
return $works;
}