void NegotiateSecurity(AuthenticationMethod[] methods)
        {
            _c.SendByte((byte)methods.Length);
            //验证密码
            VncStream.Require(methods.Length > 0,
                              "Client is not allowed in.",
                              VncFailureReason.NoSupportedAuthenticationMethods);
            foreach (var method in methods)
            {
                _c.SendByte((byte)method);
            }

            var selectedMethod = (AuthenticationMethod)_c.ReceiveByte();

            VncStream.Require(methods.Contains(selectedMethod),
                              "Invalid authentication method.",
                              VncFailureReason.UnrecognizedProtocolElement);

            bool success = true;

            if (selectedMethod == AuthenticationMethod.Password)
            {
                var challenge = VncPasswordChallenge.GenerateChallenge();
                using (new Utility.AutoClear(challenge))
                {
                    _c.Send(challenge);

                    var response = _c.Receive(16);
                    using (new Utility.AutoClear(response))
                    {
                        var e = new PasswordProvidedEventArgs(challenge, response);
                        OnPasswordProvided(e);
                        success = e.IsAuthenticated;
                    }
                }
            }

            _c.SendUInt32BE(success ? 0 : (uint)1);

            if (!success)
            {
                _c.SendString("Password authentication failed!", true);
            }

            VncStream.Require(success,
                              "Failed to authenticate.",
                              VncFailureReason.AuthenticationFailed);
        }
        public void SetDesktopSizeTest()
        {
            var framebuffer1 = new VncFramebuffer("test-1", 100, 200, VncPixelFormat.RGB32);
            var framebuffer2 = new VncFramebuffer("test-2", 200, 400, VncPixelFormat.RGB32);
            var framebuffer  = framebuffer1;

            var framebufferSourceMock = new Mock <IVncFramebufferSource>(MockBehavior.Strict);

            framebufferSourceMock
            .Setup(m => m.SetDesktopSize(200, 300))
            .Returns(ExtendedDesktopSizeStatus.Success)
            .Callback(() => { framebuffer = framebuffer2; });

            framebufferSourceMock
            .Setup(m => m.Capture())
            .Returns(() => framebuffer);

            using (var stream = new TestStream())
            {
                VncStream clientStream = new VncStream(stream.Input);

                // Negotiating the dessktop size
                clientStream.SendByte(0); // share desktop setting

                // Send a SetDesktopSize request
                clientStream.SendByte((byte)VncMessageType.SetDesktopSize);
                clientStream.SendByte(0);       // padding
                clientStream.SendUInt16BE(200); // width
                clientStream.SendUInt16BE(300); // height
                clientStream.SendByte(1);       // number of screens
                clientStream.SendByte(0);       // padding
                clientStream.SendUInt32BE(1);   // screen id
                clientStream.SendUInt16BE(0);   // x position
                clientStream.SendUInt16BE(0);   // x position
                clientStream.SendUInt16BE(200); // width
                clientStream.SendUInt16BE(300); // height
                clientStream.SendUInt32BE(0);   // flags

                stream.Input.Position = 0;

                var session = new VncServerSession();
                session.SetFramebufferSource(framebufferSourceMock.Object);
                session.Connect(stream, null, startThread: false);

                // Negotiate the desktop
                session.NegotiateDesktop();
                Assert.Equal(VncPixelFormat.RGB32, session.ClientPixelFormat);

                // Handle the SetDesktopSize request
                session.HandleMessage();

                VncStream serverStream = new VncStream(stream.Output);
                stream.Output.Position = 0;

                // Desktop negotiation result
                Assert.Equal(100, serverStream.ReceiveUInt16BE());
                Assert.Equal(200, serverStream.ReceiveUInt16BE());
                var format = serverStream.Receive(16);
                Assert.Equal("test-1", serverStream.ReceiveString());

                // SetDesktopSize result
                Assert.Equal(0, serverStream.ReceiveUInt16BE());                                         // Update rectangle request
                Assert.Equal(1, serverStream.ReceiveUInt16BE());                                         // 1 rectangle;

                Assert.Equal((ushort)ExtendedDesktopSizeReason.Client, serverStream.ReceiveUInt16BE());  // x
                Assert.Equal((ushort)ExtendedDesktopSizeStatus.Success, serverStream.ReceiveUInt16BE()); // y
                Assert.Equal(100, serverStream.ReceiveUInt16BE());                                       // width
                Assert.Equal(200, serverStream.ReceiveUInt16BE());                                       // height

                Assert.Equal((int)VncEncoding.ExtendedDesktopSize, (int)serverStream.ReceiveUInt32BE()); // encoding

                Assert.Equal(1u, serverStream.ReceiveByte());                                            // Number of screens
                serverStream.Receive(3);                                                                 // Padding
                Assert.Equal(0u, serverStream.ReceiveUInt32BE());                                        // screen ID
                Assert.Equal(0u, serverStream.ReceiveUInt16BE());                                        // x-position
                Assert.Equal(0u, serverStream.ReceiveUInt16BE());                                        // y-position
                Assert.Equal(100u, serverStream.ReceiveUInt16BE());                                      // width
                Assert.Equal(200u, serverStream.ReceiveUInt16BE());                                      // height
                Assert.Equal(0u, serverStream.ReceiveUInt32BE());                                        // flags

                Assert.Equal(stream.Output.Length, stream.Output.Position);
                Assert.Equal(stream.Input.Length, stream.Input.Position);
            }
        }