private async Task Port_R4(IOtpTransport socket, OtpInputStream ibuf)
        {
            try
            {
                int    len   = (int)(ibuf.Length - 1);
                byte[] alive = ibuf.ReadN(len);

                string name = OtpErlangString.FromEncoding(alive);
                if (traceLevel >= traceThreshold)
                {
                    Logger.Debug($"<- PORT (r4) {name}");
                }

                if (!portmap.TryGetValue(name, out AbstractNode node))
                {
                    node = null;
                }

                OtpOutputStream obuf = new OtpOutputStream();
                if (node != null)
                {
                    obuf.Write1(port4resp);
                    obuf.Write1(0);
                    obuf.Write2BE(node.Port);
                    obuf.Write1(node.Type);
                    obuf.Write1(node.Proto);
                    obuf.Write2BE(node.DistHigh);
                    obuf.Write2BE(node.DistLow);
                    obuf.Write2BE(len);
                    obuf.WriteN(alive);
                    obuf.Write2BE(0);
                    if (traceLevel >= traceThreshold)
                    {
                        Logger.Debug("-> 0 (success)");
                    }
                }
                else
                {
                    obuf.Write1(port4resp);
                    obuf.Write1(1);
                    if (traceLevel >= traceThreshold)
                    {
                        Logger.Debug("-> 1 (failure)");
                    }
                }

                await obuf.WriteToAsync(socket.OutputStream);
            }
            catch (IOException e)
            {
                if (traceLevel >= traceThreshold)
                {
                    Logger.Debug("<- (no response)");
                }
                throw new IOException("Request not responding", e);
            }
        }
 /**
  * Read string data of len from stream
  */
 public string ReadStringData(int len, string encoding = "ISO-8859-1")
 {
     byte[] strbuf = ReadN(len);
     return(OtpErlangString.FromEncoding(strbuf, encoding));
 }