SimpleHttpServer

using System;
using System.Net;
using System.Text;
using System.Threading.Tasks;

/*
 * Author:
 * Dialog
 *
 * Contact:
 * [email protected]
 */

namespace SimpleHttpServer
{
    public class HttpServer
    {
        private static readonly Random Rand = new Random();
        private readonly HttpListener _listener;

        public HttpServer(int port)
        {
            if (port < 1 || port > ushort.MaxValue)
                throw new ArgumentOutOfRangeException("Port can not be less than 1 or greater than " + ushort.MaxValue);

            _listener = new HttpListener
            {
                Prefixes = { string.Format("http://*:{0}/", port) }
            };

            _listener.Start();
            ListenAsync();
        }

        /// <summary>
        /// Listens for incoming HTTP requests on the specified port
        /// </summary>
        public async Task ListenAsync()
        {
            var context = await _listener.GetContextAsync();

            Console.WriteLine("[{0}]: Received request from {1}",
                              DateTime.Now, context.Request.RemoteEndPoint);

            SendResponseAsync(context.Response);

            ListenAsync();
        }

        /// <summary>
        /// Generates a HTML document containing a random number and writes it to the response stream
        /// </summary>
        /// <param name="response">the HttpListenerResponse for the request</param>
        /// <param name="encoding">specifies which encoding should be used. Default is UTF-8</param>
        private static async Task SendResponseAsync(HttpListenerResponse response, Encoding encoding = null)
        {
            var content = string.Format("<html>" +
                                        "<body>" +
                                        "<h1>Random number generator</h1>" +
                                        "<p>The number is: <strong>{0}</strong></p>" +
                                        "</body>" +
                                        "</html>", Rand.Next(1000));

            var contentEncoding = encoding ?? Encoding.UTF8;

            var buffer = contentEncoding.GetBytes(content);

            response.ContentLength64 = buffer.Length;
            response.ContentType = "text/html";
            response.ContentEncoding = contentEncoding;
            response.StatusCode = (int) HttpStatusCode.OK;

            using (var stream = response.OutputStream)
                await stream.WriteAsync(buffer, 0, buffer.Length);
        }
    }
}