Facebook Arcade PipeServer emulator

FacebookArcadePipeServer.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.IO.Pipes;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace PipeDream
{
    class FacebookArcadePipeServer
    {
        private static string _userId = "";
        private static string _accessToken = "";

        static void Main(string[] args)
        {
            using (NamedPipeServerStream pipeServer = new NamedPipeServerStream("FacebookArcadePipe", PipeDirection.InOut, 1, PipeTransmissionMode.Byte, PipeOptions.Asynchronous))
            {
                Console.WriteLine("Waiting for client..");
                pipeServer.BeginWaitForConnection(new AsyncCallback(ConnectionCallback), pipeServer);
                Console.ReadKey();
            }
        }

        private static readonly byte[] _buffer = new byte[1024];

        private static void ReceiveCallback(IAsyncResult result)
        {
            NamedPipeServerStream stream = (NamedPipeServerStream)result.AsyncState;
            int bytesRead = stream.EndRead(result);
            if (bytesRead > 0)
            {
                byte[] received = new byte[bytesRead];
                Array.Copy(_buffer, received, bytesRead);
                // TODO: process received
                Console.WriteLine("Received: " + System.Text.Encoding.UTF8.GetString(received, 0, received.Length));
                // <LoginRequest><AppId>xxx</AppId><Permissions /></LoginRequest>
                // https://developers.facebook.com/tools/accesstoken/?app_id=xxx

                long epochTicks = new DateTime(1970, 1, 1).Ticks;
                long unixTime = ((DateTime.UtcNow.Ticks - epochTicks) / TimeSpan.TicksPerSecond);

                //string responsev1 = "<LoginResponse><expiresIn>0</expiresIn><grantedScopes>email,public_profile</grantedScopes><userID>" + userId + "</userID><accessToken>" + accessToken + "</accessToken></LoginResponse>";
                string responsev2 = "<LoginResponse><last_refresh>0</last_refresh><expiration_timestamp>0</expiration_timestamp><permissions>email,public_profile</permissions><user_id>" 
                    + _userId + "</user_id><access_token>" + _accessToken + "</access_token></LoginResponse>";
                
                byte[] buffer = ASCIIEncoding.ASCII.GetBytes(responsev2);
                stream.Write(buffer, 0, buffer.Length);
                stream.Flush();

                Console.WriteLine("Sent: " + responsev2);

                stream.BeginRead(_buffer, 0, _buffer.Length, ReceiveCallback, stream);
            }
        }

        private static void ConnectionCallback(IAsyncResult result)
        {
            NamedPipeServerStream stream = (NamedPipeServerStream)result.AsyncState;
            stream.EndWaitForConnection(result);
            Console.WriteLine("Client connected!");
            stream.BeginRead(_buffer, 0, _buffer.Length, ReceiveCallback, stream);           
        }
    }
}