CODEWITHSUNDEEP
c#.netsocketssystem.net.sockets
paperduck
paperduck

Reputation: 1195

Why does Socket.BeginAccept() not work in my background service DLL project?

C# .NET 4.5 Visual Studio 2010

This is more of a thought exercise than proof-reading my code.

I am working on developing an HTTP listener that runs as a service in Windows. I made a standalone Windows Forms project using the below code and it works fine. Every time a request came in I was able to make a message box appear that showed the body of the HTTP POST Request.

The problem is that the same code, when copied into a background service DLL project, doesn't "catch" the HTTP requests that are sent to it. This apparent in the log file I use to debug (see the calls to Log.Write() in the code below).

I am running this all on the same PC, so I don't think the issue is that the port is in use, or that I am using the wrong IP.

I am wondering if the HTTP listener doesn't work because it's a background service, or maybe because it's a DLL.

IP address below changed to 1.2.3.4 for security reasons.

class http_listener
{

    bool _stop;

    main ()
    { 
        _stop = false;

        // start ListenForEvents() in new thread
        // [code omitted]
    }

    private void ListenForEvents(object o)
    {
        Socket _socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
        System.Net.IPAddress ipAddress = System.Net.IPAddress.Parse("1.2.3.4");
        System.Net.EndPoint endPoint = new System.Net.IPEndPoint(ipAddress, 8000);
        _socket.Bind(endPoint);
        _socket.Listen(1000);

        while (!_stop)
        { 
            Log.Write("this IS written to log every 2 seconds");
            Thread.Sleep(2000);
            _recvBufSize = 1000; // max bytes to recieve
            _begAcceptResult = _socket.BeginAccept(null, _recvBufSize, new AsyncCallback(RequestCallback), _socket);
        }
        _eventListenerThread = null;
    }



    private void RequestCallback(IAsyncResult begAcceptResult)
    {
        Log.Write("this is NOT written to log");
        Socket socket = (Socket)begAcceptResult.AsyncState;
        byte[] buf;
        int bytesTransferred;
        Socket endSocket = socket.EndAccept(out buf, out bytesTransferred, begAcceptResult);
        string stringTransferred = Encoding.ASCII.GetString(buf, 0, bytesTransferred);
        Log.Write(stringTransferred);
    }

}

Upvotes: 0

Views: 841

Answers (1)

paperduck
paperduck

Reputation: 1195

Got it working. For some reason the port I wanted to use was blocked by Windows Firewall when I ran my server as a service, but it did not block it when I ran the server as a Forms application. The service had an exception listed in the Firewall settings, but the exception only allowed communication on one particular port; not the one I wanted to use.

Here is the setting I changed to allow communication on my port:

Control Panel > Windows Firewall > Advanced Settings > Inbound Rules > (right-click name of service) > Properties > "Protocols and Ports" tab > Local port > added 8000 to the port(s) already listed there

Upvotes: 1

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