A connect request was made on an already connected socket

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a connect request was made on an already connected socket

what type of msg this?

What I have tried:

C#

Console.WriteLine("That program can transfer small file. I've test up to 850kb file");
                Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
                // m_socWorker = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
                //String szIPSelected = "172.31.1.111";
                //String szPort = "80";

                String szIPSelected = "10.2.2.82";
                String szPort = "5800";
                int alPort = System.Convert.ToInt16(szPort, 10);


                System.Net.IPAddress remoteIPAddress = System.Net.IPAddress.Parse(szIPSelected);
                System.Net.IPEndPoint ipEnd = new System.Net.IPEndPoint(remoteIPAddress, alPort);
                sock.Connect(ipEnd);

Posted 14-May-17 19:14pm

Member 12659979

Updated 15-May-17 0:37am

Kornfeld Eliyahu Peter

v2

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Richard MacCutchan 15-May-17 3:12am

Looks like you are doing the connect more than once.

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Jochen Arndt · Answer 1 · 2017-05-15T00:37:00

You have not closed a previous connection or trying to re-connect without preparing for socket reuse.

You have to ensure that sockets are gracefully shutdown and closed. See Graceful Shutdown, Linger Options, and Socket Closure (Windows)[^].

Upon closing you should call the Socket.Disconnect Method (Boolean) (System.Net.Sockets)[^] with the reuseSocket parameter set. See also the example code at the above link that calls Shutdown first to signal the other site that the connection will be closed.

If you want to reuse a connection (using same IP and port shortly after a connection has been closed), you have to prepare the socket. Upon creation you can set the SocketOptionName.ReuseAddress option using the Socket.SetSocketOption Method (SocketOptionLevel, SocketOptionName, Object) (System.Net.Sockets)[^].

You might also set a linger time. When not doing so you have to wait until the socket is finally closed internally (usually 4 minutes). But you should not set it to very small values because that can result in losing pending data and will be a forced closing (in contrast to a graceful closing).