ports

// Whether TCP ports of a host accept a connection, the way check_tcp reads them: for each port of the list,
// the poller opens a connection to the address of the host and closes it at once, sending nothing.
// A port that refuses the connection, or does not answer within protocol:tcp:timeout, is closed: "Port
// closed" raises on it. Each port is an instance, named by its number.
need('protocol:tcp');

$wanted = variable('tcp:ports', 'text', array(
    'label' => 'Ports',
    'help'  => 'The TCP ports to open, separated by commas, for instance 22, 443, 3389.',
));

per('port', 'Ports');
output('open', 'text', array('label' => 'Port open', 'per' => 'port'));
output('connect-time', 'number', array('label' => 'Connection time', 'unit' => 'ms', 'per' => 'port'));

watch.state('closed', 'Port closed', 'open', array('critical' => array('no')));
watch.above('slow', 'Slow connection', 'connect-time', array('warning' => 200, 'critical' => 1000, 'enabled' => false));

// The list is read whole before any connection: a port written wrong stops the collector, rather than
// leave a port unwatched without a word. A port written twice is opened once.
$ports = array();
foreach (text.split($wanted, ',') as $item) {
    $port = text.trim($item);
    if ($port != '') {
        if (list.count(text.match($port, '^[1-9][0-9]{0,4}$')) == 0) {
            fail('misconfigured', 'Invalid port in the list', '"' . $port . '" is not a TCP port, from 1 to 65535');
        }
        $number = $port + 0;
        if ($number > 65535) {
            fail('misconfigured', 'Invalid port in the list', '"' . $port . '" is not a TCP port, from 1 to 65535');
        }
        $ports[$port] = $number;
    }
}
if (list.count($ports) == 0) {
    fail('misconfigured', 'No port in the list', 'Set the ports to open on the probe, for instance 22, 443.');
}

// A closed port has no connection time: only its state is returned.
foreach ($ports as $name => $number) {
    $try = tcp.connect($number);
    if ($try['open']) {
        value('open', 'yes', $name);
        value('connect-time', $try['ms'], $name);
    } else {
        value('open', 'no', $name);
    }
}