Telnet connection using c#
- by alejandrobog
Our office currently uses telnet to query an external server. The procedure is something like this.
Connect - telnet opent 128........ 25000
Query - we paste the query and then hit alt + 019
Response - We receive the response as text in the telnet window
So I’m trying to make this queries automatic using a c# app. My code is the following
First the connection. (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 send the query (No exceptions)
string data ="some query";
byte[] byData = System.Text.Encoding.ASCII.GetBytes(data);
SocketClient.Send(byData);
Then I try to receive the response
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 receive the response I get "an exsiting connetion has forcibly closed by the remote host" if open telnet and send the same query I get a response right away
Any ideas, or suggestions?
