HttpListener Server Header c#

Question

I am trying to write a C# http server for a personal project, i am wondering how i can change the returned server header from Microsoft-HTTPAPI/2.0, to something else?

 public class HttpWebServer
    {
        private HttpListener Listener;

        public void Start()
        {
            Listener = new HttpListener();
            Listener.Prefixes.Add("http://*:5555/");
            Listener.Start();
            Listener.BeginGetContext(ProcessRequest, Listener);
            Console.WriteLine("Connection Started");
        }

        public void Stop()
        {
            Listener.Stop();
        }

        private void ProcessRequest(IAsyncResult result)
        {
            HttpListener listener = (HttpListener)result.AsyncState;
            HttpListenerContext context = listener.EndGetContext(result);

            string responseString = "<html>Hello World</html>";
            byte[] buffer = Encoding.UTF8.GetBytes(responseString);

            context.Response.ContentLength64 = buffer.Length;
            System.IO.Stream output = context.Response.OutputStream;
            output.Write(buffer, 0, buffer.Length);
            output.Close();

            Listener.BeginGetContext(ProcessRequest, Listener);
        }
    }

On the basic level, I suspect that `HttpListener` calls `http.sys`, thus the Http kernel queue should be the same — Sebastian, Dec 16 '13 at 18:59

score 10 · Answer 1 · answered Apr 19 '15 at 19:41

10

I know I'm a little late but I was just recently trying to do the same thing and I accidentally came across a solution that works but I'm unsure if it has any repercussions.

Response.Headers.Add("Server", "\r\n\r\n");

answered Apr 19 '15 at 19:41

SolutionMaster5000

109
1
2

1

Yeah, this line by itself removes the Server header in response. But when after that I add another Server Header I get this: **,My Server! Microsoft-HTTPAPI/2.0** – Milad Jan 17 '17 at 11:30
TY! totally fixed it! I mean it would be cool to add my own, but /meh. – Arachnid May 17 '18 at 20:54
6

`Response.Headers.Add("Server", "");` Should also work fine. – Iain Ballard Jun 25 '18 at 09:17
this weird hack pollutes the payload – Massimo Apr 13 '19 at 12:26
This doesn't work anymore. It just throws an expection. Or somethimes, if it doesn't, it will remove other headers, because they will happen to be after two \r\n's. – user4551 Nov 19 '21 at 01:05

score 9 · Accepted Answer · answered Jan 09 '09 at 15:10

The HttpListener class encapsulates the native API, HttpSendHttpResponse Function, which as stated in the link will always append the preposterous text to the server header information.

There's no way how to fix that, unless you want to code your HttpListener from scratch.

Elijah Glover · Answer 3 · 2009-01-09T07:58:48.520

I did try, but it comes back with My Personal Server Microsoft-HTTPAPI/2.0

I have also used with no success, set, remove, add, addheader

private void ProcessRequest(IAsyncResult result)
        {
            HttpListener listener = (HttpListener)result.AsyncState;
            HttpListenerContext context = listener.EndGetContext(result);

            string responseString = "<html>Hello World</html>";
            byte[] buffer = Encoding.UTF8.GetBytes(responseString);
            context.Response.ContentLength64 = buffer.Length;

            //One
            context.Response.AddHeader("Server", "My Personal Server");

            //Two
            context.Response.Headers.Remove(HttpResponseHeader.Server);
            context.Response.Headers.Add(HttpResponseHeader.Server, "My Personal Server");

            //Three
            context.Response.Headers.Set(HttpResponseHeader.Server, "My Personal Server");

            System.IO.Stream output = context.Response.OutputStream;
            output.Write(buffer, 0, buffer.Length);
            output.Close();

            Listener.BeginGetContext(ProcessRequest, Listener);
        }

Thanks Elijah

score -2 · Answer 4 · answered Jul 19 '21 at 02:25

Arul's answer is correct, however, as Iain Ballard already noted, setting the Server header to an empty string will work, meaning the Server header will not be sent at all. Then, if you have to let the client know what your awesome app's name is, you can take the liberty of adding a "Via" header. Its specifications are rather loose and it probably gets ignored by the majority of browsers.

HttpListener Server Header c#

4 Answers4

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