Strange Characters in CLI Output while making Socket Server

Question

I am trying to test a Client-Server communication using Socket programming in PHP. After trying some samples given on PHP Reference site, the communication is working OK.

But, the problem is that I am getting some bogus or invalid characters in the buffer.

Of course, I am able to vanish them using Regex, but it would be more nice to know the reason behind this.

I think that this person is also having the same problem.

Source Code of Server:

error_reporting(E_ALL);

set_time_limit(0);

$address = "tcp://192.168.1.60:9160";

$sock = stream_socket_server($address, $errcode, $errstring);

if (!$sock) {
    echo $errcode.": ".$errstring."\n";
}
else {
    do {
        while ($client = stream_socket_accept($sock)) {
            fwrite($client, "*** Welcome ***".PHP_EOL);
            $input = trim(fgets($client, 2048));
            if (!empty($input)) {
                fwrite($client, "Server: ".$input.PHP_EOL);
            }
            else {
                fwrite($client, "--- NO INPUT ---".PHP_EOL);
            }
            echo trim($input).PHP_EOL;
            if ($fp = fopen("log.txt", "a+")) {
                fwrite($fp, trim($input).PHP_EOL);
                fclose($fp);
            }
            fclose($client);
        }
    } while (true);
}

fclose($sock);

Any help would be appreciated :)