Using get_headers() and fsockopen is nice, but in the end both will only work if allow_url_fopen is enabled in php.ini. Since fsockopen will work with all versions of PHP, I'd rather use cURL as additional option instead of get_headers(). So there'd be more of a chance that it works. Other than that it's nice. The regex could be slightly improved, and the (bool) infront of the preg_match() isn't necessary. ;)

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