How to fix: The tcp server having close waits after client disconnected

问题

I am having tcp server which gets hanged with "Close_Waits". I need to have an example program which deals with the persistent connection from the client.

I have tried catching the exceptions and then closing the socket inside the catch. But no luck!

protected virtual void ReceiveCallBack(IAsyncResult result)
{
    var wrapper = (ConnectedSocketWrapper)result.AsyncState;
    try
    {

        int bytesRead = 0;

        bytesRead = wrapper.ConnectedSocket.EndReceive(result);

        LogInfo("Byte Read" + bytesRead.ToString());

        if (bytesRead > 0)
        {
            LogInfo("inside Byte Read > 0 : " + bytesRead.ToString());
            byte[] dataRead = wrapper.Buffer.Take(bytesRead).ToArray();

            wrapper.ConnectedSocket.BeginReceive(wrapper.Buffer, 0, this.configuration.BytesToReceiveInReadOperation, SocketFlags.None, this.ReceiveCallBack, wrapper);

            DataReceivedByServer dataReceived = new DataReceivedByServer(wrapper.Token, dataRead);

            EventDispatcher.RaiseEvent(dataReceived);

            if (DataReceived != null)
            {
                DataReceived(this, new DataReceivedEventArgs(dataRead, wrapper.Token));
            }

        }
        else
        {
            EventDispatcher.RaiseEvent(new ClientDisconnected(wrapper.Token, "Read 0 bytes (client disconnected gracefully)", wrapper.ConnectedSocket.RemoteEndPoint.ToString()));

            LogInfo("inside Byte Read = 0 : " + bytesRead.ToString());
            Close(wrapper.ConnectedSocket);
            Socket removeSocket;
            connectedSockets.TryRemove(wrapper.Token, out removeSocket);
        }
    }
    catch
    {
        Close(wrapper.ConnectedSocket);
        throw;
    }

}

I need to have a hung free TCP server which handles the requests seamlessly.

回答1:

If I were you I would inspect code and/or use this one simplsockets, it's quite readable.

Also check this one MultiProtocolAspNetCore, it's about how to build TCP server on top ASP.NET Core.

Also read this awesome TCP/IP .NET Socket FAQ.

来源：https://stackoverflow.com/questions/56662099/how-to-fix-the-tcp-server-having-close-waits-after-client-disconnected