HttpListenerRequest.ContentLength64 Property

public static void ShowRequestData (HttpListenerRequest request)
{
    if (!request.HasEntityBody)
    {
        Console.WriteLine("No client data was sent with the request.");
        return;
    }
    System.IO.Stream body = request.InputStream;
    System.Text.Encoding encoding = request.ContentEncoding;
    System.IO.StreamReader reader = new System.IO.StreamReader(body, encoding);
    if (request.ContentType != null)
    {
        Console.WriteLine("Client data content type {0}", request.ContentType);
    }
    Console.WriteLine("Client data content length {0}", request.ContentLength64);

    Console.WriteLine("Start of client data:");
    // Convert the data to a string and display it on the console.
    string s = reader.ReadToEnd();
    Console.WriteLine(s);
    Console.WriteLine("End of client data:");
    body.Close();
    reader.Close();
    // If you are finished with the request, it should be closed also.
}