WSAETIMEDOUT message in Synapse Library

Question

Why I always get WSAETIMEDOUT error in this code :

var fUDPBuf: array [1..UdpPacketSize] of byte;
{...}
UDPSocket := TUDPBlockSocket.Create;
UDPSocket.Bind(UDPIP, UDPPort);
if UDPSocket.LastError = 0 then
  Raise EDevFail.Create(Format(SPortFailed, [UDPPort]));

while not Terminated do begin
  BytesRead := UDPSocket.RecvBufferEx(@fUDPBuf[1], UdpPacketSize, 1000);
  if BytesRead <= 0 then
    case UDPSocket.LastError of
      0, WSAETIMEDOUT: Continue;
      WSAECONNRESET, WSAENETRESET,
      WSAENOTCONN, WSAECONNABORTED,
      WSAENETDOWN: begin
                     Raise EDevFail.Create(UDPSocket.GetErrorDesc(UDPSocket.LastError));
                     UDPSocket.CloseSocket;
                   end;
      else begin
        Raise EDevFail.Create(UDPSocket.GetErrorDesc(UDPSocket.LastError));
        UDPSocket.CloseSocket;
      end;
    end;

  //Sleep(1);
  ProcessData(@fUDPBuf[1]);
  inc(PacketCount);
end;

I'm sure that I receive UDP data from e network device as much as UdpPacketSize.

Answer 1

In the call "UDPSocket.RecvBufferEx(@fUDPBuf[1], UdpPacketSize, 1000);" I would presume that the last number is the timeout period. This is done so that it doesn't sit waiting forever, but rather checks periodically if the thread has been Terminated using the while loop condition. So the timeout is a normal situation for this sort of code, and can be ignored.

Answer 2

I found that. The error is in

if UDPSocket.LastError = 0 then

LastError is 10049=Can't assign requested address at this point. So why I couldn't Bind the UDPIP address. I've check the IP and Port. These are correct. And there is no other software listening this port.

Answer 3

I solved my problem :)

UDPSocket.Bind(UDPIP, UDPPort);

must be

UDPSocket.Bind('0.0.0.0', UDPPort);

And

if UDPSocket.LastError = 0 then

must be

if UDPSocket.LastError <> 0 then

For to check IP address where data come from

if UDPSocket.GetRemoteSinIP<>UDPIP then ....