Currently, our office uses telnet to request an external server. The procedure is something like this.
- Connect - telnet opent 128 ........ 25000
- Request - we insert the request, and then press alt + 019
- Answer. We get the answer in the form of text in the telnet window.
So, I am trying to automate these requests using a C # application. My code is as follows
Connection first. (With no exceptions)
SocketClient = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); String szIPSelected = txtIPAddress.Text; String szPort = txtPort.Text; int alPort = System.Convert.ToInt16(szPort, 10); System.Net.IPAddress remoteIPAddress = System.Net.IPAddress.Parse(szIPSelected); System.Net.IPEndPoint remoteEndPoint = new System.Net.IPEndPoint(remoteIPAddress, alPort); SocketClient.Connect(remoteEndPoint);
Then I submit the request (no exceptions)
string data ="some query"; byte[] byData = System.Text.Encoding.ASCII.GetBytes(data); SocketClient.Send(byData);
Then i try to get an answer
byte[] buffer = new byte[10]; Receive(SocketClient, buffer, 0, buffer.Length, 10000); string str = Encoding.ASCII.GetString(buffer, 0, buffer.Length); txtDataRx.Text = str; public static void Receive(Socket socket, byte[] buffer, int offset, int size, int timeout) { int startTickCount = Environment.TickCount; int received = 0; // how many bytes is already received do { if (Environment.TickCount > startTickCount + timeout) throw new Exception("Timeout."); try { received += socket.Receive(buffer, offset + received, size - received, SocketFlags.None); } catch (SocketException ex) { if (ex.SocketErrorCode == SocketError.WouldBlock || ex.SocketErrorCode == SocketError.IOPending || ex.SocketErrorCode == SocketError.NoBufferSpaceAvailable) { // socket buffer is probably empty, wait and try again Thread.Sleep(30); } else throw ex; // any serious error occurr } } while (received < size); }
Every time I try to get a response, I get a “force connection closed by the remote host”, if telnet is open and sends the same request, I immediately get a response
Any ideas or suggestions?