protected override CommandStream.PipelineInstruction PipelineCallback(CommandStream.PipelineEntry entry, ResponseDescription response, bool timeout, ref Stream stream)
        {
            if (response == null)
            {
                return CommandStream.PipelineInstruction.Abort;
            }
            FtpStatusCode status = (FtpStatusCode) response.Status;
            if (status != FtpStatusCode.ClosingControl)
            {
                this.StatusCode = status;
                this.StatusLine = response.StatusDescription;
            }
            if (response.InvalidStatusCode)
            {
                throw new WebException(SR.GetString("net_InvalidStatusCode"), WebExceptionStatus.ProtocolError);
            }
            if (base.m_Index == -1)
            {
                switch (status)
                {
                    case FtpStatusCode.SendUserCommand:
                        this.m_BannerMessage = new StringBuilder();
                        this.m_BannerMessage.Append(this.StatusLine);
                        return CommandStream.PipelineInstruction.Advance;

                    case FtpStatusCode.ServiceTemporarilyNotAvailable:
                        return CommandStream.PipelineInstruction.Reread;
                }
                throw base.GenerateException(status, response.StatusDescription, null);
            }
            if (entry.Command == "OPTS utf8 on\r\n")
            {
                if (response.PositiveCompletion)
                {
                    base.Encoding = Encoding.UTF8;
                }
                else
                {
                    base.Encoding = Encoding.Default;
                }
                return CommandStream.PipelineInstruction.Advance;
            }
            if (entry.Command.IndexOf("USER") != -1)
            {
                if (status == FtpStatusCode.LoggedInProceed)
                {
                    this.m_LoginState = FtpLoginState.LoggedIn;
                    base.m_Index++;
                }
                else if ((status == FtpStatusCode.NotLoggedIn) && (this.m_LoginState != FtpLoginState.NotLoggedIn))
                {
                    this.m_LoginState = FtpLoginState.ReloginFailed;
                    throw ExceptionHelper.IsolatedException;
                }
            }
            if (response.TransientFailure || response.PermanentFailure)
            {
                if (status == FtpStatusCode.ServiceNotAvailable)
                {
                    base.MarkAsRecoverableFailure();
                }
                throw base.GenerateException(status, response.StatusDescription, null);
            }
            if ((this.m_LoginState != FtpLoginState.LoggedIn) && (entry.Command.IndexOf("PASS") != -1))
            {
                switch (status)
                {
                    case FtpStatusCode.NeedLoginAccount:
                    case FtpStatusCode.LoggedInProceed:
                        this.m_LoginState = FtpLoginState.LoggedIn;
                        goto Label_017A;
                }
                throw base.GenerateException(status, response.StatusDescription, null);
            }
        Label_017A:
            if (entry.HasFlag(CommandStream.PipelineEntryFlags.CreateDataConnection) && (response.PositiveCompletion || response.PositiveIntermediate))
            {
                bool flag;
                CommandStream.PipelineInstruction instruction = this.QueueOrCreateDataConection(entry, response, timeout, ref stream, out flag);
                if (!flag)
                {
                    return instruction;
                }
            }
            switch (status)
            {
                case FtpStatusCode.OpeningData:
                case FtpStatusCode.DataAlreadyOpen:
                {
                    if (this.m_DataSocket == null)
                    {
                        return CommandStream.PipelineInstruction.Abort;
                    }
                    if (!entry.HasFlag(CommandStream.PipelineEntryFlags.GiveDataStream))
                    {
                        base.m_AbortReason = SR.GetString("net_ftp_invalid_status_response", new object[] { status, entry.Command });
                        return CommandStream.PipelineInstruction.Abort;
                    }
                    this.TryUpdateContentLength(response.StatusDescription);
                    FtpWebRequest request = (FtpWebRequest) base.m_Request;
                    if (request.MethodInfo.ShouldParseForResponseUri)
                    {
                        this.TryUpdateResponseUri(response.StatusDescription, request);
                    }
                    return this.QueueOrCreateFtpDataStream(ref stream);
                }
                case FtpStatusCode.LoggedInProceed:
                    this.m_WelcomeMessage.Append(this.StatusLine);
                    break;

                case FtpStatusCode.ClosingControl:
                    this.m_ExitMessage.Append(response.StatusDescription);
                    base.CloseSocket();
                    break;

                case FtpStatusCode.ServerWantsSecureSession:
                {
                    FtpWebRequest initiatingRequest = (FtpWebRequest) base.m_Request;
                    TlsStream stream2 = new TlsStream(initiatingRequest.RequestUri.Host, base.NetworkStream, initiatingRequest.ClientCertificates, base.Pool.ServicePoint, initiatingRequest, base.m_Async ? initiatingRequest.GetWritingContext().ContextCopy : null);
                    base.NetworkStream = stream2;
                    break;
                }
                case FtpStatusCode.FileStatus:
                {
                    FtpWebRequest request1 = (FtpWebRequest) base.m_Request;
                    if (entry.Command.StartsWith("SIZE "))
                    {
                        this.m_ContentLength = this.GetContentLengthFrom213Response(response.StatusDescription);
                    }
                    else if (entry.Command.StartsWith("MDTM "))
                    {
                        this.m_LastModified = this.GetLastModifiedFrom213Response(response.StatusDescription);
                    }
                    break;
                }
                default:
                    if (status == FtpStatusCode.PathnameCreated)
                    {
                        if ((entry.Command == "PWD\r\n") && !entry.HasFlag(CommandStream.PipelineEntryFlags.UserCommand))
                        {
                            this.m_LoginDirectory = this.GetLoginDirectory(response.StatusDescription);
                        }
                    }
                    else if (entry.Command.IndexOf("CWD") != -1)
                    {
                        this.m_EstablishedServerDirectory = this.m_RequestedServerDirectory;
                    }
                    break;
            }
            if (!response.PositiveIntermediate && (base.UsingSecureStream || !(entry.Command == "AUTH TLS\r\n")))
            {
                return CommandStream.PipelineInstruction.Advance;
            }
            return CommandStream.PipelineInstruction.Reread;
        }