pfSense

/* check if a interface is part of a gateway group */

function interface_gateway_group_member($interface) {

	global $config;

	$realif = get_real_interface($interface);

	if(is_array($config['gateways']['gateway_group']))

		$groups = $config['gateways']['gateway_group'];

	else

		return false;

	foreach($groups as $group) {

		if(is_array($group['item'])) {

			foreach($group['item'] as $item) {

				$elements = explode("|", $item);

				$gwname = $elements[0];

				$gwif = lookup_gateway_interface_by_name($gwname);

				if($gwif == $interface)

				return $group['name'];

			}

		}

	}

	return false;

}