HttpServer.cs

public class Program {
  private static async System.Threading.Tasks.Task Listen(System.Net.HttpListener listener) {
    while (true) {
      try {
        System.Net.HttpListenerContext context =
            await listener.GetContextAsync().ConfigureAwait(false);
        System.Net.HttpListenerRequest request = context.Request;
        System.Net.HttpListenerResponse response = context.Response;
        string text = System.Web.HttpUtility.UrlDecode(request.Url.AbsolutePath).Substring(1);
        System.Console.WriteLine(text);
        byte[] bytes = System.Text.Encoding.UTF8.GetBytes(text);
        response.ContentType = "text/plain";
        response.ContentEncoding = System.Text.Encoding.UTF8;
        response.ContentLength64 = bytes.LongLength;
        await response.OutputStream.WriteAsync(bytes);
        response.Close();
      } catch (System.Exception exception) {
        System.Console.WriteLine(exception.Message);
      }
    }
  }
  public static async System.Threading.Tasks.Task Main() {
    System.Net.HttpListener listener = new();
    listener.Prefixes.Add("http://localhost/");
    listener.Start();
    System.Console.CancelKeyPress += delegate {
      listener.Close();
    };
    System.Collections.Generic.IEnumerator<string> prefixes = listener.Prefixes.GetEnumerator();
    prefixes.MoveNext();
    System.Console.WriteLine("Listening for connections on " + prefixes.Current);
    await Listen(listener);
  }
}