Synnefo » Pithos MS Client

// -----------------------------------------------------------------------

// <copyright file="PithosAccount.cs" company="GRNet">

// Copyright 2011-2012 GRNET S.A. All rights reserved.

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using System.IO;

using Pithos.Network;

using log4net;

namespace Pithos.Client.WPF

{

    using System;

    using System.Collections.Generic;

    using System.Linq;

    using System.Text;

    using System.Net;

    using System.Threading.Tasks;

    using System.Diagnostics.Contracts;

    using System.Diagnostics;

    using System.Net.Sockets;

    /// <summary>

    /// TODO: Update summary.

    /// </summary>

    /// <summary>

    /// Retrieves an account name and token from PITHOS

    /// </summary>

    public static class PithosAccount

    {

        private static readonly ILog Log = LogManager.GetLogger(typeof(PithosAccount));

        /// <summary>

        /// Asynchronously retrieves PITHOS credentials

        /// </summary>

        /// <param name="loginUrl">URL to retrieve the account info from PITHOS. Must end with =</param>

        /// <returns>The credentials wrapped in a Task</returns>

        public static Task<NetworkCredential> RetrieveCredentials(string loginUrl)

        {

            Contract.Requires(Uri.IsWellFormedUriString(loginUrl, UriKind.Absolute));

            if (!Uri.IsWellFormedUriString(loginUrl, UriKind.Absolute))

                throw new ArgumentException("The pithosSite parameter must be a valid absolute URL", "loginUrl");

            int port = GetFreePort();

            //TODO:Force logout here to take care of existing cookies

            var listenerUrl = String.Format("http://127.0.0.1:{0}/", port);

            var receiveCredentials = ListenForRedirectAsync(port);

            var uriBuilder=new UriBuilder(loginUrl);                       

            uriBuilder.Query="next=" + listenerUrl;

            var retrieveUri = uriBuilder.Uri;

            Log.InfoFormat("[RETRIEVE] Open Browser at {0}", retrieveUri);

            Process.Start(retrieveUri.ToString());

            return receiveCredentials;

        }

        private static async Task<NetworkCredential> ListenHttpForRedirectAsync(string listenerUrl)

        {

            using (var listener = new HttpListener())

            {

                listener.Prefixes.Add(listenerUrl);

                Log.InfoFormat("[RETRIEVE] Listening at {0}", listenerUrl);

                try

                {

                    listener.Start();

                    var context = await listener.GetContextAsync()

                                            .WithTimeout(TimeSpan.FromMinutes(5));

                    var request = context.Request;

                    Log.InfoFormat("[RETRIEVE] Got Connection {0}", request.RawUrl);

                    var query = request.QueryString;

                    var userName = query["user"];

                    var token = query["token"];

                    if (String.IsNullOrWhiteSpace(userName) ||

                        String.IsNullOrWhiteSpace(token))

                    {

                        Respond(context, "Failure", "The server did not return a username or token");

                        Log.ErrorFormat("[RETRIEVE] No credentials returned by server");

                        throw new Exception("The server did not return a username or token");

                    }

                    else

                    {

                        Log.InfoFormat("[RETRIEVE] Credentials retrieved user:{0} token:{1}", userName, token);

                        Respond(context, "Authenticated", "Got It");

                        return new NetworkCredential(userName, token);

                    }

                }

                catch (Exception exc)

                {

                    Log.Error("[RETRIEVE][ERROR] Receive connection {0}", exc);

                    throw;

                }

            }

        }

        private static async Task<NetworkCredential> ListenForRedirectAsync(int port)

        {

            var listener = new TcpListener(IPAddress.Any, port);            

            Log.InfoFormat("[RETRIEVE] Listening at {0}", port);

            try

            {

                listener.Start();

                using (var client = await listener.AcceptTcpClientAsync()

                                        .WithTimeout(TimeSpan.FromMinutes(5)))

                {

                    using (var stream = client.GetStream())

                    using (var reader=new StreamReader(stream))

                    {

                        var request = await reader.ReadLineAsync();

                        //BUG

                        //TODO: Add proper warnings here if the content is empty, don't just throw an exception

                        //This may be a common occurence 

                        if (String.IsNullOrWhiteSpace(request))

                            throw new Exception("Nothing retrieved");

                        Log.InfoFormat("[RETRIEVE] Got Connection {0}", request);

                        var items = ParseResponse(request);

                        var userName = items["user"];

                        var token = items["token"];

                        if (String.IsNullOrWhiteSpace(userName) ||

                            String.IsNullOrWhiteSpace(token))

                        {

                            Respond(stream, "Failure", "The server did not return a username or token");

                            Log.ErrorFormat("[RETRIEVE] No credentials returned by server");

                            throw new Exception("The server did not return a username or token");

                        }

                        else

                        {

                            Log.InfoFormat("[RETRIEVE] Credentials retrieved user:{0} token:{1}", userName, token);

                            Respond(stream, "Authenticated", "Got It");                            

                        }

                        return new NetworkCredential(userName, token);

                    }

                }

            }

            catch (Exception exc)

            {

                Log.Error("[RETRIEVE][ERROR] Receive connection {0}", exc);

                throw;

            }

        }

        private static Dictionary<string, string> ParseResponse(string request)

        {

            var parts = request.Split(' ');

            var query = parts[1].TrimStart('/', '?');

            var items = query.Split('&')

                .Select(pair => pair.Split('='))

                .ToDictionary(arr => arr[0].ToLower(), arr => Uri.UnescapeDataString(arr[1]));

            return items;

        }

        private static void Respond(HttpListenerContext context,string title,string message)

        {

            var response = context.Response;

            var html = String.Format("<html><head><title>{0}</title></head><body><h1>{1}</h1></body></html>", title, message);

            var outBuffer = Encoding.UTF8.GetBytes(html);

            response.ContentLength64 = outBuffer.Length;

            using (var stream = response.OutputStream)

            {

                stream.Write(outBuffer, 0, outBuffer.Length);

            }

            Log.InfoFormat("[RETRIEVE] Responded");

        }

        private static void Respond(Stream stream,string title,string message)

        {

            var html = String.Format("<html><head><title>{0}</title></head><body><h1>{1}</h1></body></html>", title, message);

            var response = new StringBuilder();

            response.AppendLine("HTTP/1.1 200 OK");

            response.AppendFormat("Content-Length: {0}\n", html.Length);

            response.AppendLine("Server: Microsoft-HTTPAPI/2.0");

            response.AppendFormat("Date: {0}\n\n", DateTime.UtcNow);

            response.AppendLine(html);

            var outBuffer=Encoding.UTF8.GetBytes(response.ToString());

            stream.Write(outBuffer, 0, outBuffer.Length);

            Log.InfoFormat("[RETRIEVE] Responded");

        }

        /// <summary>

        /// Locates a free local port 

        /// </summary>

        /// <returns>A free port</returns>

        /// <remarks>The method starts and stops a TcpListener on port 0 to locate a free port.</remarks>

        public static int GetFreePort()

        {

            //The TcpListener will locate a free port             

            var listener = new TcpListener(IPAddress.Any, 0);

            listener.Start();

            var port = ((IPEndPoint)listener.LocalEndpoint).Port;

            listener.Stop();

            return port;

        }

    }

}