•  29-06-2023
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Question

The .NET has a built in HttpListener class, however I was wondering how I could roll my own Http Listener. I know there are a lot of implications to this, but I just want see the browser and my own app interact with each other.

This is the code I have written so far:

Socket servSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
servSocket.ExclusiveAddressUse = false; // Does this matter?
servSocket.Bind(new IPEndPoint(IPAddress.Any, 8080));
servSocket.Listen(10);

byte[] buffer;

do
{
    try
    {
        Socket clientSocket = servSocket.Accept();

        Console.WriteLine("Received Request at: {0}.", DateTime.Now);

        EndPoint remoteEP = clientSocket.RemoteEndPoint;
        buffer = new byte[1024];
        clientSocket.ReceiveFrom(buffer, SocketFlags.None, ref remoteEP);
        string request = Encoding.UTF8.GetString(buffer);
        System.Diagnostics.Trace.Write(request);
        buffer = Encoding.UTF8.GetBytes("<html><head><link rel=\"icon\" href=\"data:;base64,=\"></head><body></body></html>");
        clientSocket.Send(buffer);

        clientSocket.Close();
        clientSocket.Dispose();
    }
    catch { }
}
while (this.isRunning);

This sort of works, however two issues I have noted, is that the clientSocket local end-point is on the same port as the servSocket. With the built-in HttpListener, the request gets handled by a random local end-point port. How can I mimic this?

I have set the ExclusiveAddressUse flag to false, however I still cannot bind more than one socket to that particular end-point, so what is its exact use?

Furthermore, from time to time I get a SocketException with 'An established connection was aborted by the software in your host machine'. What could be the source of the problem?

Was it helpful?

Solution

The simple answer is "you don't really care about that".

TCP works by estabilishing a two-way "virtual" persistent connection. To achieve this illusion, it uses a separate port for communication with a given client. You still connect to port 80 (for example), but a thousand clients use a thousand different ports for the actual communication with the server.

ExclusiveAddressUse allows you to bind more sockets to the same port - but each has to have its own IP address.

Networking is hard. Us as high an abstraction as you can, be it TcpListener, HttpListener or even OWIN.

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