获取主机域名函数

function PMA_getenv($var_name) {
	if (isset ( $_SERVER [$var_name] )) {
		return $_SERVER [$var_name];
	} elseif (isset ( $_ENV [$var_name] )) {
		return $_ENV [$var_name];
	} elseif (getenv ( $var_name )) {
		return getenv ( $var_name );
	} elseif (function_exists ( 'apache_getenv' ) && apache_getenv ( $var_name, true )) {
		return apache_getenv ( $var_name, true );
	}
	return '';
}
if (empty ( $HTTP_HOST )) {
	if (PMA_getenv ( 'HTTP_HOST' )) {
		$HTTP_HOST = PMA_getenv ( 'HTTP_HOST' );
	} else {
		$HTTP_HOST = '';
	}
}
echo htmlspecialchars ( $HTTP_HOST );