define("SERVER_ADDR", "localhost");
define("SERVER_PORT", "1234");

$server_socket = false;

if (! ($server_socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP))) {
    die("socket_create failed: ". socket_strerror(socket_last_error()));
}

if (! socket_set_option($server_socket, SOL_SOCKET, SO_REUSEADDR, 1)) {
    die("socket_set_option failed: ". socket_strerror(socket_last_error()));
}

if (! socket_set_nonblock($server_socket)) {
    die("socket_set_nonblock failed: ". socket_strerror(socket_last_error()));
}

if (! socket_bind($server_socket, SERVER_ADDR, SERVER_PORT)) {
    die("socket_bind failed: ". socket_strerror(socket_last_error()));
}
if (! socket_listen($server_socket)) {
    die("socket_listen failed: ". socket_strerror(socket_last_error()));
}

$clients = array();

while (1) {
    $read = $clients;
    $read[] = $server_socket;
    $write = null;
    $except = null;

    $rv = socket_select($read, $write, $except, 0, 100000);

    if ($rv === false) {
        socket_close($server_socket);
        die("select() returned false: ". socket_strerror(socket_last_error()) );
    }

    if ($rv) {
        foreach($read as $fd) {
            if ($fd == $server_socket) {
                $client = socket_accept($server_socket);

                if (!$client) {
                    socket_close($server_socket);
                    die("socket_accept() failed: ". socket_strerror(socket_last_error()) );
                }

                $clients[] = $client;
            } else {
                // will only reliably work if data comes in small chunks
                $data = socket_read($fd, 4096);

                .........
            }
        }
    } else {
        // timeout
    }
}