gistfile1.cs

            //send join request to server and wait for response.
            //the initial join should be blocking since if we fail to connect we should not listing for packets

            var joinRequest = new byte[2];
            joinRequest = BitConverter.GetBytes((short) SystemMessage.Join);
            _udpService.Send(joinRequest, joinRequest.Length, _joinedSessionEndPoint);

            int timeOut = 1000;

            //we should give the server some time to respond.
            //Lets say a max length of 1000ms before dropping the connect

            var asyncResult = _udpService.BeginReceive(null, null);
            asyncResult.AsyncWaitHandle.WaitOne(timeOut);
            if (asyncResult.IsCompleted)
            {
                IPEndPoint host = null;
                var hostResponse = _udpService.EndReceive(asyncResult, ref host);
                if (hostResponse.Length == 2)
                {
                    var message = (SystemMessage) BitConverter.ToInt16(hostResponse, 0);
                    if (message == SystemMessage.JoinAccepted)
                    {
                        // Now we should retrieve the session member list.
                        _udpService.Send(BitConverter.GetBytes((short) SystemMessage.RequestMemberList), 2,
                            _joinedSessionEndPoint);
                        asyncResult = _udpService.BeginReceive(null, null);
                        asyncResult.AsyncWaitHandle.WaitOne(timeOut);
                        if (asyncResult.IsCompleted)
                        {
                            hostResponse = _udpService.EndReceive(asyncResult, ref host);
                            if (hostResponse.Length >= 6)
                            {
                                message = (SystemMessage) BitConverter.ToInt16(hostResponse, 0);
                                if (message == SystemMessage.MemberList)
                                {
                                    int length = BitConverter.ToInt32(hostResponse, 2);
                                    var memList = new List<SessionMember>();
                                    byte[] ipBytes = new byte[4];
                                    for (int i = 0; i < length; i++)
                                    {
                                        int offsetIp = 8 * i + 6;

                                        Array.Copy(hostResponse, offsetIp, ipBytes, 0, 4);
                                        var ip = new IPAddress(ipBytes);
                                        int port = BitConverter.ToInt32(hostResponse, offsetIp + 4);

                                        memList.Add(new SessionMember(new IPEndPoint(ip, port)));
                                    }
                                    _members.Clear();
                                    _members.AddRange(memList.ToArray());
                                    _sessionActive = true;
                                }
                                else
                                {
                                    throw new NetworkSessionException(
                                        "The remote host responded with an unexpected packet.");
                                }
                            }
                            else
                            {
                                throw new NetworkSessionException(
                                    "The remote host responded with an invalid packet size.");
                            }
                        }
                        else
                        {
                            throw new NetworkSessionException("The remote host took to long to respond.");
                        }
                    }
                    else if(message == SystemMessage.JoinRefused)
                    {
                        throw new NetworkSessionException("Connection refused by remote host.");
                    }
                }
                else
                {
                    throw new NetworkSessionException("The remote host responded with an invalid packet size.");
                }
            }
            else
            {
                //the server took to long to respond.
                throw new NetworkSessionException("The remote host took to long to respond.");
            }
            
            //connection is confirmed by host, we can now listing for packets.
            _checkActivityTask.Start();
            var remoteEndPoint = new IPEndPoint(IPAddress.Any, 0);
            _udpService.BeginReceive(AsynClientReceiveCallback, new AsyncReceiveState(_udpService, remoteEndPoint));