VERY basic BYOND topic request

Byond.java

public final class Byond
{
  public static String makeRequest(String url, int port, String topic) throws IOException
  {
    Socket sock = new Socket(url, port);
    //Socket sock = new Socket("localhost", 4567);
    InputStream is = sock.getInputStream();
    OutputStream os = sock.getOutputStream();

    byte[] msg = ("?" + topic).getBytes();
    os.write(0x00);
    os.write(0x83);
    os.write(0);
    os.write(msg.length + 6);
    os.write(new byte[]{0, 0, 0, 0, 0});
    os.write(msg);
    os.write(0);
    os.flush();

    byte[] header = new byte[5];
    is.read(header);

    int msb = Byte.toUnsignedInt(header[2]);
    int lsb = Byte.toUnsignedInt(header[3]);
    int respLen = (int)Integer.toUnsignedLong((msb << 8) | lsb);

    //System.out.println("Reading " + respLen + " bytes...");
    byte[] responseBuffer = new byte[respLen];
    is.read(responseBuffer);
    CharsetDecoder decoder = StandardCharsets.ISO_8859_1.newDecoder();
    CharBuffer charBuffer = decoder.decode(ByteBuffer.wrap(responseBuffer));
    sock.close();
    return charBuffer.toString();
  }
}