Non-blocking tcp scanner in PHP

pscan.php

<?php

// Optional mappings
$port_service = array(
    20 => "ftp-data",
    21 => "ftp",
    22 => "ssh",
    23 => "telnet",
    24 => "priv-mail",
    25 => "smtp",
    53 => "domain",
    80 => "http",
    110 => "pop3",
    119 => "nntp",
    135 => "msrpc",
    143 => "imap",
    220 => "imap3",
    443 => "https",
    993 => "imaps",
    1248 => "hermes",
    3306 => "mysql",
    5432 => "postgresql",
    5666 => "nrpe",
    6556 => "check_mk",
    9999 => "abyss"
);

class Scanner {
    private $host;

    function __construct($host) {
        $this->host = $host;
    }

    private function sockets_create($host, $ports) {
        $sockets = [];
        foreach($ports as $port) {
            $socket = socket_create(AF_INET , SOCK_STREAM , SOL_TCP);
            socket_set_nonblock($socket);
            @socket_connect($socket, $host, $port);
            $sockets[$port] = $socket;
        }
        return $sockets;
    }

    private function sockets_poll($sockets) {
        global $port_service;
        $ports_open = [];
        $start = microtime(true);

        while ($sockets && microtime(true) - $start < 3) {
            $null = null;
            $write = $sockets;
            socket_select($null, $write, $null, 0, 50000);
            foreach ($write as $port => $sock) {
                // @TODO - check for SOCKET_ETIMEDOUT and SOCKET_ECONNREFUSED if needed
                if (socket_get_option($sock, SOL_SOCKET, SO_ERROR) === 0) {
                    $service = array_key_exists($port, $port_service) ? $port_service[$port]:"Unknown";
                    array_push($ports_open, ["number"=>$port, "service"=>$service]);
                }
                unset($sockets[$port]);
                socket_close($sock);
            }
        }
        return $ports_open;
    }

    public function probe_ports($ports) {
        $sockets = $this->sockets_create($this->host, $ports);
        return $this->sockets_poll($sockets);
    }
}

$scanner = new Scanner("google.com");
$open = $scanner->probe_ports([22, 80, 53, 111, 8080]);
print_r($open, false);