/*
 * noVNC: HTML5 VNC client
 * Copyright (C) 2020 The noVNC authors
 * Licensed under MPL 2.0 (see LICENSE.txt)
 *
 * See README.md for usage and integration instructions.
 *
 */

import { toUnsigned32bit, toSigned32bit } from './util/int.js';
import * as Log from './util/logging.js';
import { encodeUTF8, decodeUTF8 } from './util/strings.js';
import { dragThreshold, supportsWebCodecsH264Decode } from './util/browser.js';
import { clientToElement } from './util/element.js';
import { setCapture } from './util/events.js';
import EventTargetMixin from './util/eventtarget.js';
import Display from "./display.js";
import Inflator from "./inflator.js";
import Deflator from "./deflator.js";
import Keyboard from "./input/keyboard.js";
import GestureHandler from "./input/gesturehandler.js";
import Cursor from "./util/cursor.js";
import Websock from "./websock.js";
import KeyTable from "./input/keysym.js";
import XtScancode from "./input/xtscancodes.js";
import { encodings } from "./encodings.js";
import RSAAESAuthenticationState from "./ra2.js";
import legacyCrypto from "./crypto/crypto.js";

import RawDecoder from "./decoders/raw.js";
import CopyRectDecoder from "./decoders/copyrect.js";
import RREDecoder from "./decoders/rre.js";
import HextileDecoder from "./decoders/hextile.js";
import ZlibDecoder from './decoders/zlib.js';
import TightDecoder from "./decoders/tight.js";
import TightPNGDecoder from "./decoders/tightpng.js";
import ZRLEDecoder from "./decoders/zrle.js";
import JPEGDecoder from "./decoders/jpeg.js";
import H264Decoder from "./decoders/h264.js";

// How many seconds to wait for a disconnect to finish
const DISCONNECT_TIMEOUT = 3;
const DEFAULT_BACKGROUND = 'rgb(40, 40, 40)';

// Minimum wait (ms) between two mouse moves
const MOUSE_MOVE_DELAY = 17;

// Wheel thresholds
const WHEEL_STEP = 50; // Pixels needed for one step
const WHEEL_LINE_HEIGHT = 19; // Assumed pixels for one line step

// Gesture thresholds
const GESTURE_ZOOMSENS = 75;
const GESTURE_SCRLSENS = 50;
const DOUBLE_TAP_TIMEOUT = 1000;
const DOUBLE_TAP_THRESHOLD = 50;

// Security types
const securityTypeNone              = 1;
const securityTypeVNCAuth           = 2;
const securityTypeRA2ne             = 6;
const securityTypeTight             = 16;
const securityTypeVeNCrypt          = 19;
const securityTypeXVP               = 22;
const securityTypeARD               = 30;
const securityTypeMSLogonII         = 113;

// Special Tight security types
const securityTypeUnixLogon         = 129;

// VeNCrypt security types
const securityTypePlain             = 256;

// Extended clipboard pseudo-encoding formats
const extendedClipboardFormatText   = 1;
/*eslint-disable no-unused-vars */
const extendedClipboardFormatRtf    = 1 << 1;
const extendedClipboardFormatHtml   = 1 << 2;
const extendedClipboardFormatDib    = 1 << 3;
const extendedClipboardFormatFiles  = 1 << 4;
/*eslint-enable */

// Extended clipboard pseudo-encoding actions
const extendedClipboardActionCaps    = 1 << 24;
const extendedClipboardActionRequest = 1 << 25;
const extendedClipboardActionPeek    = 1 << 26;
const extendedClipboardActionNotify  = 1 << 27;
const extendedClipboardActionProvide = 1 << 28;

export default class RFB extends EventTargetMixin {
    constructor(target, urlOrChannel, options) {
        if (!target) {
            throw new Error("Must specify target");
        }
        if (!urlOrChannel) {
            throw new Error("Must specify URL, WebSocket or RTCDataChannel");
        }

        // We rely on modern APIs which might not be available in an
        // insecure context
        if (!window.isSecureContext) {
            Log.Error("noVNC requires a secure context (TLS). Expect crashes!");
        }

        super();

        this._target = target;

        if (typeof urlOrChannel === "string") {
            this._url = urlOrChannel;
        } else {
            this._url = null;
            this._rawChannel = urlOrChannel;
        }

        // Connection details
        options = options || {};
        this._rfbCredentials = options.credentials || {};
        this._shared = 'shared' in options ? !!options.shared : true;
        this._repeaterID = options.repeaterID || '';
        this._wsProtocols = options.wsProtocols || [];

        // Internal state
        this._rfbConnectionState = '';
        this._rfbInitState = '';
        this._rfbAuthScheme = -1;
        this._rfbCleanDisconnect = true;
        this._rfbRSAAESAuthenticationState = null;

        // Server capabilities
        this._rfbVersion = 0;
        this._rfbMaxVersion = 3.8;
        this._rfbTightVNC = false;
        this._rfbVeNCryptState = 0;
        this._rfbXvpVer = 0;

        this._fbWidth = 0;
        this._fbHeight = 0;

        this._fbName = "";

        this._capabilities = { power: false };

        this._supportsFence = false;

        this._supportsContinuousUpdates = false;
        this._enabledContinuousUpdates = false;

        this._supportsSetDesktopSize = false;
        this._screenID = 0;
        this._screenFlags = 0;
        this._pendingRemoteResize = false;
        this._lastResize = 0;

        this._qemuExtKeyEventSupported = false;

        this._extendedPointerEventSupported = false;

        this._clipboardText = null;
        this._clipboardServerCapabilitiesActions = {};
        this._clipboardServerCapabilitiesFormats = {};

        // Internal objects
        this._sock = null;              // Websock object
        this._display = null;           // Display object
        this._flushing = false;         // Display flushing state
        this._keyboard = null;          // Keyboard input handler object
        this._gestures = null;          // Gesture input handler object
        this._resizeObserver = null;    // Resize observer object

        // Timers
        this._disconnTimer = null;      // disconnection timer
        this._resizeTimeout = null;     // resize rate limiting
        this._mouseMoveTimer = null;

        // Decoder states
        this._decoders = {};

        this._FBU = {
            rects: 0,
            x: 0,
            y: 0,
            width: 0,
            height: 0,
            encoding: null,
        };

        // Mouse state
        this._mousePos = {};
        this._mouseButtonMask = 0;
        this._mouseLastMoveTime = 0;
        this._viewportDragging = false;
        this._viewportDragPos = {};
        this._viewportHasMoved = false;
        this._accumulatedWheelDeltaX = 0;
        this._accumulatedWheelDeltaY = 0;

        // Gesture state
        this._gestureLastTapTime = null;
        this._gestureFirstDoubleTapEv = null;
        this._gestureLastMagnitudeX = 0;
        this._gestureLastMagnitudeY = 0;

        // Bound event handlers
        this._eventHandlers = {
            focusCanvas: this._focusCanvas.bind(this),
            handleResize: this._handleResize.bind(this),
            handleMouse: this._handleMouse.bind(this),
            handleWheel: this._handleWheel.bind(this),
            handleGesture: this._handleGesture.bind(this),
            handleRSAAESCredentialsRequired: this._handleRSAAESCredentialsRequired.bind(this),
            handleRSAAESServerVerification: this._handleRSAAESServerVerification.bind(this),
        };

        // main setup
        Log.Debug(">> RFB.constructor");

        // Create DOM elements
        this._screen = document.createElement('div');
        this._screen.style.display = 'flex';
        this._screen.style.width = '100%';
        this._screen.style.height = '100%';
        this._screen.style.overflow = 'auto';
        this._screen.style.background = DEFAULT_BACKGROUND;
        this._canvas = document.createElement('canvas');
        this._canvas.style.margin = 'auto';
        // Some browsers add an outline on focus
        this._canvas.style.outline = 'none';
        this._canvas.width = 0;
        this._canvas.height = 0;
        this._canvas.tabIndex = -1;
        this._screen.appendChild(this._canvas);

        // Cursor
        this._cursor = new Cursor();

        // XXX: TightVNC 2.8.11 sends no cursor at all until Windows changes
        // it. Result: no cursor at all until a window border or an edit field
        // is hit blindly. But there are also VNC servers that draw the cursor
        // in the framebuffer and don't send the empty local cursor. There is
        // no way to satisfy both sides.
        //
        // The spec is unclear on this "initial cursor" issue. Many other
        // viewers (TigerVNC, RealVNC, Remmina) display an arrow as the
        // initial cursor instead.
        this._cursorImage = RFB.cursors.none;

        // populate decoder array with objects
        this._decoders[encodings.encodingRaw] = new RawDecoder();
        this._decoders[encodings.encodingCopyRect] = new CopyRectDecoder();
        this._decoders[encodings.encodingRRE] = new RREDecoder();
        this._decoders[encodings.encodingHextile] = new HextileDecoder();
        this._decoders[encodings.encodingZlib] = new ZlibDecoder();
        this._decoders[encodings.encodingTight] = new TightDecoder();
        this._decoders[encodings.encodingTightPNG] = new TightPNGDecoder();
        this._decoders[encodings.encodingZRLE] = new ZRLEDecoder();
        this._decoders[encodings.encodingJPEG] = new JPEGDecoder();
        this._decoders[encodings.encodingH264] = new H264Decoder();

        // NB: nothing that needs explicit teardown should be done
        // before this point, since this can throw an exception
        try {
            this._display = new Display(this._canvas);
        } catch (exc) {
            Log.Error("Display exception: " + exc);
            throw exc;
        }

        this._keyboard = new Keyboard(this._canvas);
        this._keyboard.onkeyevent = this._handleKeyEvent.bind(this);
        this._remoteCapsLock = null; // Null indicates unknown or irrelevant
        this._remoteNumLock = null;

        this._gestures = new GestureHandler();

        this._sock = new Websock();
        this._sock.on('open', this._socketOpen.bind(this));
        this._sock.on('close', this._socketClose.bind(this));
        this._sock.on('message', this._handleMessage.bind(this));
        this._sock.on('error', this._socketError.bind(this));

        this._expectedClientWidth = null;
        this._expectedClientHeight = null;
        this._resizeObserver = new ResizeObserver(this._eventHandlers.handleResize);

        // All prepared, kick off the connection
        this._updateConnectionState('connecting');

        Log.Debug("<< RFB.constructor");

        // ===== PROPERTIES =====

        this.dragViewport = false;
        this.focusOnClick = true;

        this._viewOnly = false;
        this._clipViewport = false;
        this._clippingViewport = false;
        this._scaleViewport = false;
        this._resizeSession = false;

        this._showDotCursor = false;
        if (options.showDotCursor !== undefined) {
            Log.Warn("Specifying showDotCursor as a RFB constructor argument is deprecated");
            this._showDotCursor = options.showDotCursor;
        }

        this._qualityLevel = 6;
        this._compressionLevel = 2;
    }

    // ===== PROPERTIES =====

    get viewOnly() { return this._viewOnly; }
    set viewOnly(viewOnly) {
        this._viewOnly = viewOnly;

        if (this._rfbConnectionState === "connecting" ||
            this._rfbConnectionState === "connected") {
            if (viewOnly) {
                this._keyboard.ungrab();
            } else {
                this._keyboard.grab();
            }
        }
    }

    get capabilities() { return this._capabilities; }

    get clippingViewport() { return this._clippingViewport; }
    _setClippingViewport(on) {
        if (on === this._clippingViewport) {
            return;
        }
        this._clippingViewport = on;
        this.dispatchEvent(new CustomEvent("clippingviewport",
                                           { detail: this._clippingViewport }));
    }

    get touchButton() { return 0; }
    set touchButton(button) { Log.Warn("Using old API!"); }

    get clipViewport() { return this._clipViewport; }
    set clipViewport(viewport) {
        this._clipViewport = viewport;
        this._updateClip();
    }

    get scaleViewport() { return this._scaleViewport; }
    set scaleViewport(scale) {
        this._scaleViewport = scale;
        // Scaling trumps clipping, so we may need to adjust
        // clipping when enabling or disabling scaling
        if (scale && this._clipViewport) {
            this._updateClip();
        }
        this._updateScale();
        if (!scale && this._clipViewport) {
            this._updateClip();
        }
    }

    get resizeSession() { return this._resizeSession; }
    set resizeSession(resize) {
        this._resizeSession = resize;
        if (resize) {
            this._requestRemoteResize();
        }
    }

    get showDotCursor() { return this._showDotCursor; }
    set showDotCursor(show) {
        this._showDotCursor = show;
        this._refreshCursor();
    }

    get background() { return this._screen.style.background; }
    set background(cssValue) { this._screen.style.background = cssValue; }

    get qualityLevel() {
        return this._qualityLevel;
    }
    set qualityLevel(qualityLevel) {
        if (!Number.isInteger(qualityLevel) || qualityLevel < 0 || qualityLevel > 9) {
            Log.Error("qualityLevel must be an integer between 0 and 9");
            return;
        }

        if (this._qualityLevel === qualityLevel) {
            return;
        }

        this._qualityLevel = qualityLevel;

        if (this._rfbConnectionState === 'connected') {
            this._sendEncodings();
        }
    }

    get compressionLevel() {
        return this._compressionLevel;
    }
    set compressionLevel(compressionLevel) {
        if (!Number.isInteger(compressionLevel) || compressionLevel < 0 || compressionLevel > 9) {
            Log.Error("compressionLevel must be an integer between 0 and 9");
            return;
        }

        if (this._compressionLevel === compressionLevel) {
            return;
        }

        this._compressionLevel = compressionLevel;

        if (this._rfbConnectionState === 'connected') {
            this._sendEncodings();
        }
    }

    // ===== PUBLIC METHODS =====

    disconnect() {
        this._updateConnectionState('disconnecting');
        this._sock.off('error');
        this._sock.off('message');
        this._sock.off('open');
        if (this._rfbRSAAESAuthenticationState !== null) {
            this._rfbRSAAESAuthenticationState.disconnect();
        }
    }

    approveServer() {
        if (this._rfbRSAAESAuthenticationState !== null) {
            this._rfbRSAAESAuthenticationState.approveServer();
        }
    }

    sendCredentials(creds) {
        this._rfbCredentials = creds;
        this._resumeAuthentication();
    }

    sendCtrlAltDel() {
        if (this._rfbConnectionState !== 'connected' || this._viewOnly) { return; }
        Log.Info("Sending Ctrl-Alt-Del");

        this.sendKey(KeyTable.XK_Control_L, "ControlLeft", true);
        this.sendKey(KeyTable.XK_Alt_L, "AltLeft", true);
        this.sendKey(KeyTable.XK_Delete, "Delete", true);
        this.sendKey(KeyTable.XK_Delete, "Delete", false);
        this.sendKey(KeyTable.XK_Alt_L, "AltLeft", false);
        this.sendKey(KeyTable.XK_Control_L, "ControlLeft", false);
    }

    machineShutdown() {
        this._xvpOp(1, 2);
    }

    machineReboot() {
        this._xvpOp(1, 3);
    }

    machineReset() {
        this._xvpOp(1, 4);
    }

    // Send a key press. If 'down' is not specified then send a down key
    // followed by an up key.
    sendKey(keysym, code, down) {
        if (this._rfbConnectionState !== 'connected' || this._viewOnly) { return; }

        if (down === undefined) {
            this.sendKey(keysym, code, true);
            this.sendKey(keysym, code, false);
            return;
        }

        const scancode = XtScancode[code];

        if (this._qemuExtKeyEventSupported && scancode) {
            // 0 is NoSymbol
            keysym = keysym || 0;

            Log.Info("Sending key (" + (down ? "down" : "up") + "): keysym " + keysym + ", scancode " + scancode);

            RFB.messages.QEMUExtendedKeyEvent(this._sock, keysym, down, scancode);
        } else {
            if (!keysym) {
                return;
            }
            Log.Info("Sending keysym (" + (down ? "down" : "up") + "): " + keysym);
            RFB.messages.keyEvent(this._sock, keysym, down ? 1 : 0);
        }
    }

    focus(options) {
        this._canvas.focus(options);
    }

    blur() {
        this._canvas.blur();
    }

    clipboardPasteFrom(text) {
        if (this._rfbConnectionState !== 'connected' || this._viewOnly) { return; }

        if (this._clipboardServerCapabilitiesFormats[extendedClipboardFormatText] &&
            this._clipboardServerCapabilitiesActions[extendedClipboardActionNotify]) {

            this._clipboardText = text;
            RFB.messages.extendedClipboardNotify(this._sock, [extendedClipboardFormatText]);
        } else {
            let length, i;
            let data;

            length = 0;
            // eslint-disable-next-line no-unused-vars
            for (let codePoint of text) {
                length++;
            }

            data = new Uint8Array(length);

            i = 0;
            for (let codePoint of text) {
                let code = codePoint.codePointAt(0);

                /* Only ISO 8859-1 is supported */
                if (code > 0xff) {
                    code = 0x3f; // '?'
                }

                data[i++] = code;
            }

            RFB.messages.clientCutText(this._sock, data);
        }
    }

    getImageData() {
        return this._display.getImageData();
    }

    toDataURL(type, encoderOptions) {
        return this._display.toDataURL(type, encoderOptions);
    }

    toBlob(callback, type, quality) {
        return this._display.toBlob(callback, type, quality);
    }

    // ===== PRIVATE METHODS =====

    _connect() {
        Log.Debug(">> RFB.connect");

        if (this._url) {
            Log.Info(`connecting to ${this._url}`);
            this._sock.open(this._url, this._wsProtocols);
        } else {
            Log.Info(`attaching ${this._rawChannel} to Websock`);
            this._sock.attach(this._rawChannel);

            if (this._sock.readyState === 'closed') {
                throw Error("Cannot use already closed WebSocket/RTCDataChannel");
            }

            if (this._sock.readyState === 'open') {
                // FIXME: _socketOpen() can in theory call _fail(), which
                //        isn't allowed this early, but I'm not sure that can
                //        happen without a bug messing up our state variables
                this._socketOpen();
            }
        }

        // Make our elements part of the page
        this._target.appendChild(this._screen);

        this._gestures.attach(this._canvas);

        this._cursor.attach(this._canvas);
        this._refreshCursor();

        // Monitor size changes of the screen element
        this._resizeObserver.observe(this._screen);

        // Always grab focus on some kind of click event
        this._canvas.addEventListener("mousedown", this._eventHandlers.focusCanvas);
        this._canvas.addEventListener("touchstart", this._eventHandlers.focusCanvas);

        // Mouse events
        this._canvas.addEventListener('mousedown', this._eventHandlers.handleMouse);
        this._canvas.addEventListener('mouseup', this._eventHandlers.handleMouse);
        this._canvas.addEventListener('mousemove', this._eventHandlers.handleMouse);
        // Prevent middle-click pasting (see handler for why we bind to document)
        this._canvas.addEventListener('click', this._eventHandlers.handleMouse);
        // preventDefault() on mousedown doesn't stop this event for some
        // reason so we have to explicitly block it
        this._canvas.addEventListener('contextmenu', this._eventHandlers.handleMouse);

        // Wheel events
        this._canvas.addEventListener("wheel", this._eventHandlers.handleWheel);

        // Gesture events
        this._canvas.addEventListener("gesturestart", this._eventHandlers.handleGesture);
        this._canvas.addEventListener("gesturemove", this._eventHandlers.handleGesture);
        this._canvas.addEventListener("gestureend", this._eventHandlers.handleGesture);

        Log.Debug("<< RFB.connect");
    }

    _disconnect() {
        Log.Debug(">> RFB.disconnect");
        this._cursor.detach();
        this._canvas.removeEventListener("gesturestart", this._eventHandlers.handleGesture);
        this._canvas.removeEventListener("gesturemove", this._eventHandlers.handleGesture);
        this._canvas.removeEventListener("gestureend", this._eventHandlers.handleGesture);
        this._canvas.removeEventListener("wheel", this._eventHandlers.handleWheel);
        this._canvas.removeEventListener('mousedown', this._eventHandlers.handleMouse);
        this._canvas.removeEventListener('mouseup', this._eventHandlers.handleMouse);
        this._canvas.removeEventListener('mousemove', this._eventHandlers.handleMouse);
        this._canvas.removeEventListener('click', this._eventHandlers.handleMouse);
        this._canvas.removeEventListener('contextmenu', this._eventHandlers.handleMouse);
        this._canvas.removeEventListener("mousedown", this._eventHandlers.focusCanvas);
        this._canvas.removeEventListener("touchstart", this._eventHandlers.focusCanvas);
        this._resizeObserver.disconnect();
        this._keyboard.ungrab();
        this._gestures.detach();
        this._sock.close();
        try {
            this._target.removeChild(this._screen);
        } catch (e) {
            if (e.name === 'NotFoundError') {
                // Some cases where the initial connection fails
                // can disconnect before the _screen is created
            } else {
                throw e;
            }
        }
        clearTimeout(this._resizeTimeout);
        clearTimeout(this._mouseMoveTimer);
        Log.Debug("<< RFB.disconnect");
    }

    _socketOpen() {
        if ((this._rfbConnectionState === 'connecting') &&
            (this._rfbInitState === '')) {
            this._rfbInitState = 'ProtocolVersion';
            Log.Debug("Starting VNC handshake");
        } else {
            this._fail("Unexpected server connection while " +
                       this._rfbConnectionState);
        }
    }

    _socketClose(e) {
        Log.Debug("WebSocket on-close event");
        let msg = "";
        if (e.code) {
            msg = "(code: " + e.code;
            if (e.reason) {
                msg += ", reason: " + e.reason;
            }
            msg += ")";
        }
        switch (this._rfbConnectionState) {
            case 'connecting':
                this._fail("Connection closed " + msg);
                break;
            case 'connected':
                // Handle disconnects that were initiated server-side
                this._updateConnectionState('disconnecting');
                this._updateConnectionState('disconnected');
                break;
            case 'disconnecting':
                // Normal disconnection path
                this._updateConnectionState('disconnected');
                break;
            case 'disconnected':
                this._fail("Unexpected server disconnect " +
                           "when already disconnected " + msg);
                break;
            default:
                this._fail("Unexpected server disconnect before connecting " +
                           msg);
                break;
        }
        this._sock.off('close');
        // Delete reference to raw channel to allow cleanup.
        this._rawChannel = null;
    }

    _socketError(e) {
        Log.Warn("WebSocket on-error event");
    }

    _focusCanvas(event) {
        if (!this.focusOnClick) {
            return;
        }

        this.focus({ preventScroll: true });
    }

    _setDesktopName(name) {
        this._fbName = name;
        this.dispatchEvent(new CustomEvent(
            "desktopname",
            { detail: { name: this._fbName } }));
    }

    _saveExpectedClientSize() {
        this._expectedClientWidth = this._screen.clientWidth;
        this._expectedClientHeight = this._screen.clientHeight;
    }

    _currentClientSize() {
        return [this._screen.clientWidth, this._screen.clientHeight];
    }

    _clientHasExpectedSize() {
        const [currentWidth, currentHeight] = this._currentClientSize();
        return currentWidth == this._expectedClientWidth &&
            currentHeight == this._expectedClientHeight;
    }

    // Handle browser window resizes
    _handleResize() {
        // Don't change anything if the client size is already as expected
        if (this._clientHasExpectedSize()) {
            return;
        }
        // If the window resized then our screen element might have
        // as well. Update the viewport dimensions.
        window.requestAnimationFrame(() => {
            this._updateClip();
            this._updateScale();
            this._saveExpectedClientSize();
        });

        // Request changing the resolution of the remote display to
        // the size of the local browser viewport.
        this._requestRemoteResize();
    }

    // Update state of clipping in Display object, and make sure the
    // configured viewport matches the current screen size
    _updateClip() {
        const curClip = this._display.clipViewport;
        let newClip = this._clipViewport;

        if (this._scaleViewport) {
            // Disable viewport clipping if we are scaling
            newClip = false;
        }

        if (curClip !== newClip) {
            this._display.clipViewport = newClip;
        }

        if (newClip) {
            // When clipping is enabled, the screen is limited to
            // the size of the container.
            const size = this._screenSize();
            this._display.viewportChangeSize(size.w, size.h);
            this._fixScrollbars();
            this._setClippingViewport(size.w < this._display.width ||
                                      size.h < this._display.height);
        } else {
            this._setClippingViewport(false);
        }

        // When changing clipping we might show or hide scrollbars.
        // This causes the expected client dimensions to change.
        if (curClip !== newClip) {
            this._saveExpectedClientSize();
        }
    }

    _updateScale() {
        if (!this._scaleViewport) {
            this._display.scale = 1.0;
        } else {
            const size = this._screenSize();
            this._display.autoscale(size.w, size.h);
        }
        this._fixScrollbars();
    }

    // Requests a change of remote desktop size. This message is an extension
    // and may only be sent if we have received an ExtendedDesktopSize message
    _requestRemoteResize() {
        if (!this._resizeSession) {
            return;
        }
        if (this._viewOnly) {
            return;
        }
        if (!this._supportsSetDesktopSize) {
            return;
        }

        // Rate limit to one pending resize at a time
        if (this._pendingRemoteResize) {
            return;
        }

        // And no more than once every 100ms
        if ((Date.now() - this._lastResize) < 100) {
            clearTimeout(this._resizeTimeout);
            this._resizeTimeout = setTimeout(this._requestRemoteResize.bind(this),
                                             100 - (Date.now() - this._lastResize));
            return;
        }
        this._resizeTimeout = null;

        const size = this._screenSize();

        // Do we actually change anything?
        if (size.w === this._fbWidth && size.h === this._fbHeight) {
            return;
        }

        this._pendingRemoteResize = true;
        this._lastResize = Date.now();
        RFB.messages.setDesktopSize(this._sock,
                                    Math.floor(size.w), Math.floor(size.h),
                                    this._screenID, this._screenFlags);

        Log.Debug('Requested new desktop size: ' +
                   size.w + 'x' + size.h);
    }

    // Gets the the size of the available screen
    _screenSize() {
        let r = this._screen.getBoundingClientRect();
        return { w: r.width, h: r.height };
    }

    _fixScrollbars() {
        // This is a hack because Safari on macOS screws up the calculation
        // for when scrollbars are needed. We get scrollbars when making the
        // browser smaller, despite remote resize being enabled. So to fix it
        // we temporarily toggle them off and on.
        const orig = this._screen.style.overflow;
        this._screen.style.overflow = 'hidden';
        // Force Safari to recalculate the layout by asking for
        // an element's dimensions
        this._screen.getBoundingClientRect();
        this._screen.style.overflow = orig;
    }

    /*
     * Connection states:
     *   connecting
     *   connected
     *   disconnecting
     *   disconnected - permanent state
     */
    _updateConnectionState(state) {
        const oldstate = this._rfbConnectionState;

        if (state === oldstate) {
            Log.Debug("Already in state '" + state + "', ignoring");
            return;
        }

        // The 'disconnected' state is permanent for each RFB object
        if (oldstate === 'disconnected') {
            Log.Error("Tried changing state of a disconnected RFB object");
            return;
        }

        // Ensure proper transitions before doing anything
        switch (state) {
            case 'connected':
                if (oldstate !== 'connecting') {
                    Log.Error("Bad transition to connected state, " +
                               "previous connection state: " + oldstate);
                    return;
                }
                break;

            case 'disconnected':
                if (oldstate !== 'disconnecting') {
                    Log.Error("Bad transition to disconnected state, " +
                               "previous connection state: " + oldstate);
                    return;
                }
                break;

            case 'connecting':
                if (oldstate !== '') {
                    Log.Error("Bad transition to connecting state, " +
                               "previous connection state: " + oldstate);
                    return;
                }
                break;

            case 'disconnecting':
                if (oldstate !== 'connected' && oldstate !== 'connecting') {
                    Log.Error("Bad transition to disconnecting state, " +
                               "previous connection state: " + oldstate);
                    return;
                }
                break;

            default:
                Log.Error("Unknown connection state: " + state);
                return;
        }

        // State change actions

        this._rfbConnectionState = state;

        Log.Debug("New state '" + state + "', was '" + oldstate + "'.");

        if (this._disconnTimer && state !== 'disconnecting') {
            Log.Debug("Clearing disconnect timer");
            clearTimeout(this._disconnTimer);
            this._disconnTimer = null;

            // make sure we don't get a double event
            this._sock.off('close');
        }

        switch (state) {
            case 'connecting':
                this._connect();
                break;

            case 'connected':
                this.dispatchEvent(new CustomEvent("connect", { detail: {} }));
                break;

            case 'disconnecting':
                this._disconnect();

                this._disconnTimer = setTimeout(() => {
                    Log.Error("Disconnection timed out.");
                    this._updateConnectionState('disconnected');
                }, DISCONNECT_TIMEOUT * 1000);
                break;

            case 'disconnected':
                this.dispatchEvent(new CustomEvent(
                    "disconnect", { detail:
                                    { clean: this._rfbCleanDisconnect } }));
                break;
        }
    }

    /* Print errors and disconnect
     *
     * The parameter 'details' is used for information that
     * should be logged but not sent to the user interface.
     */
    _fail(details) {
        switch (this._rfbConnectionState) {
            case 'disconnecting':
                Log.Error("Failed when disconnecting: " + details);
                break;
            case 'connected':
                Log.Error("Failed while connected: " + details);
                break;
            case 'connecting':
                Log.Error("Failed when connecting: " + details);
                break;
            default:
                Log.Error("RFB failure: " + details);
                break;
        }
        this._rfbCleanDisconnect = false; //This is sent to the UI

        // Transition to disconnected without waiting for socket to close
        this._updateConnectionState('disconnecting');
        this._updateConnectionState('disconnected');

        return false;
    }

    _setCapability(cap, val) {
        this._capabilities[cap] = val;
        this.dispatchEvent(new CustomEvent("capabilities",
                                           { detail: { capabilities: this._capabilities } }));
    }

    _handleMessage() {
        if (this._sock.rQwait("message", 1)) {
            Log.Warn("handleMessage called on an empty receive queue");
            return;
        }

        switch (this._rfbConnectionState) {
            case 'disconnected':
                Log.Error("Got data while disconnected");
                break;
            case 'connected':
                while (true) {
                    if (this._flushing) {
                        break;
                    }
                    if (!this._normalMsg()) {
                        break;
                    }
                    if (this._sock.rQwait("message", 1)) {
                        break;
                    }
                }
                break;
            case 'connecting':
                while (this._rfbConnectionState === 'connecting') {
                    if (!this._initMsg()) {
                        break;
                    }
                }
                break;
            default:
                Log.Error("Got data while in an invalid state");
                break;
        }
    }

    _handleKeyEvent(keysym, code, down, numlock, capslock) {
        // If remote state of capslock is known, and it doesn't match the local led state of
        // the keyboard, we send a capslock keypress first to bring it into sync.
        // If we just pressed CapsLock, or we toggled it remotely due to it being out of sync
        // we clear the remote state so that we don't send duplicate or spurious fixes,
        // since it may take some time to receive the new remote CapsLock state.
        if (code == 'CapsLock' && down) {
            this._remoteCapsLock = null;
        }
        if (this._remoteCapsLock !== null && capslock !== null && this._remoteCapsLock !== capslock && down) {
            Log.Debug("Fixing remote caps lock");

            this.sendKey(KeyTable.XK_Caps_Lock, 'CapsLock', true);
            this.sendKey(KeyTable.XK_Caps_Lock, 'CapsLock', false);
            // We clear the remote capsLock state when we do this to prevent issues with doing this twice
            // before we receive an update of the the remote state.
            this._remoteCapsLock = null;
        }

        // Logic for numlock is exactly the same.
        if (code == 'NumLock' && down) {
            this._remoteNumLock = null;
        }
        if (this._remoteNumLock !== null && numlock !== null && this._remoteNumLock !== numlock && down) {
            Log.Debug("Fixing remote num lock");
            this.sendKey(KeyTable.XK_Num_Lock, 'NumLock', true);
            this.sendKey(KeyTable.XK_Num_Lock, 'NumLock', false);
            this._remoteNumLock = null;
        }
        this.sendKey(keysym, code, down);
    }

    static _convertButtonMask(buttons) {
        /* The bits in MouseEvent.buttons property correspond
         * to the following mouse buttons:
         *     0: Left
         *     1: Right
         *     2: Middle
         *     3: Back
         *     4: Forward
         *
         * These bits needs to be converted to what they are defined as
         * in the RFB protocol.
         */

        const buttonMaskMap = {
            0: 1 << 0, // Left
            1: 1 << 2, // Right
            2: 1 << 1, // Middle
            3: 1 << 7, // Back
            4: 1 << 8, // Forward
        };

        let bmask = 0;
        for (let i = 0; i < 5; i++) {
            if (buttons & (1 << i)) {
                bmask |= buttonMaskMap[i];
            }
        }
        return bmask;
    }

    _handleMouse(ev) {
        /*
         * We don't check connection status or viewOnly here as the
         * mouse events might be used to control the viewport
         */

        if (ev.type === 'click') {
            /*
             * Note: This is only needed for the 'click' event as it fails
             *       to fire properly for the target element so we have
             *       to listen on the document element instead.
             */
            if (ev.target !== this._canvas) {
                return;
            }
        }

        // FIXME: if we're in view-only and not dragging,
        //        should we stop events?
        ev.stopPropagation();
        ev.preventDefault();

        if ((ev.type === 'click') || (ev.type === 'contextmenu')) {
            return;
        }

        let pos = clientToElement(ev.clientX, ev.clientY,
                                  this._canvas);

        let bmask = RFB._convertButtonMask(ev.buttons);

        let down = ev.type == 'mousedown';
        switch (ev.type) {
            case 'mousedown':
            case 'mouseup':
                if (this.dragViewport) {
                    if (down && !this._viewportDragging) {
                        this._viewportDragging = true;
                        this._viewportDragPos = {'x': pos.x, 'y': pos.y};
                        this._viewportHasMoved = false;

                        this._flushMouseMoveTimer(pos.x, pos.y);

                        // Skip sending mouse events, instead save the current
                        // mouse mask so we can send it later.
                        this._mouseButtonMask = bmask;
                        break;
                    } else {
                        this._viewportDragging = false;

                        // If we actually performed a drag then we are done
                        // here and should not send any mouse events
                        if (this._viewportHasMoved) {
                            this._mouseButtonMask = bmask;
                            break;
                        }
                        // Otherwise we treat this as a mouse click event.
                        // Send the previously saved button mask, followed
                        // by the current button mask at the end of this
                        // function.
                        this._sendMouse(pos.x, pos.y,  this._mouseButtonMask);
                    }
                }
                if (down) {
                    setCapture(this._canvas);
                }
                this._handleMouseButton(pos.x, pos.y, bmask);
                break;
            case 'mousemove':
                if (this._viewportDragging) {
                    const deltaX = this._viewportDragPos.x - pos.x;
                    const deltaY = this._viewportDragPos.y - pos.y;

                    if (this._viewportHasMoved || (Math.abs(deltaX) > dragThreshold ||
                                                   Math.abs(deltaY) > dragThreshold)) {
                        this._viewportHasMoved = true;

                        this._viewportDragPos = {'x': pos.x, 'y': pos.y};
                        this._display.viewportChangePos(deltaX, deltaY);
                    }

                    // Skip sending mouse events
                    break;
                }
                this._handleMouseMove(pos.x, pos.y);
                break;
        }
    }

    _handleMouseButton(x, y, bmask) {
        // Flush waiting move event first
        this._flushMouseMoveTimer(x, y);

        this._mouseButtonMask = bmask;
        this._sendMouse(x, y, this._mouseButtonMask);
    }

    _handleMouseMove(x, y) {
        this._mousePos = { 'x': x, 'y': y };

        // Limit many mouse move events to one every MOUSE_MOVE_DELAY ms
        if (this._mouseMoveTimer == null) {

            const timeSinceLastMove = Date.now() - this._mouseLastMoveTime;
            if (timeSinceLastMove > MOUSE_MOVE_DELAY) {
                this._sendMouse(x, y, this._mouseButtonMask);
                this._mouseLastMoveTime = Date.now();
            } else {
                // Too soon since the latest move, wait the remaining time
                this._mouseMoveTimer = setTimeout(() => {
                    this._handleDelayedMouseMove();
                }, MOUSE_MOVE_DELAY - timeSinceLastMove);
            }
        }
    }

    _handleDelayedMouseMove() {
        this._mouseMoveTimer = null;
        this._sendMouse(this._mousePos.x, this._mousePos.y,
                        this._mouseButtonMask);
        this._mouseLastMoveTime = Date.now();
    }

    _sendMouse(x, y, mask) {
        if (this._rfbConnectionState !== 'connected') { return; }
        if (this._viewOnly) { return; } // View only, skip mouse events

        // Highest bit in mask is never sent to the server
        if (mask & 0x8000) {
            throw new Error("Illegal mouse button mask (mask: " + mask + ")");
        }

        let extendedMouseButtons = mask & 0x7f80;

        if (this._extendedPointerEventSupported && extendedMouseButtons) {
            RFB.messages.extendedPointerEvent(this._sock, this._display.absX(x),
                                              this._display.absY(y), mask);
        } else {
            RFB.messages.pointerEvent(this._sock, this._display.absX(x),
                                      this._display.absY(y), mask);
        }
    }

    _handleWheel(ev) {
        if (this._rfbConnectionState !== 'connected') { return; }
        if (this._viewOnly) { return; } // View only, skip mouse events

        ev.stopPropagation();
        ev.preventDefault();

        let pos = clientToElement(ev.clientX, ev.clientY,
                                  this._canvas);

        let bmask = RFB._convertButtonMask(ev.buttons);
        let dX = ev.deltaX;
        let dY = ev.deltaY;

        // Pixel units unless it's non-zero.
        // Note that if deltamode is line or page won't matter since we aren't
        // sending the mouse wheel delta to the server anyway.
        // The difference between pixel and line can be important however since
        // we have a threshold that can be smaller than the line height.
        if (ev.deltaMode !== 0) {
            dX *= WHEEL_LINE_HEIGHT;
            dY *= WHEEL_LINE_HEIGHT;
        }

        // Mouse wheel events are sent in steps over VNC. This means that the VNC
        // protocol can't handle a wheel event with specific distance or speed.
        // Therefor, if we get a lot of small mouse wheel events we combine them.
        this._accumulatedWheelDeltaX += dX;
        this._accumulatedWheelDeltaY += dY;


        // Generate a mouse wheel step event when the accumulated delta
        // for one of the axes is large enough.
        if (Math.abs(this._accumulatedWheelDeltaX) >= WHEEL_STEP) {
            if (this._accumulatedWheelDeltaX < 0) {
                this._handleMouseButton(pos.x, pos.y, bmask | 1 << 5);
                this._handleMouseButton(pos.x, pos.y, bmask);
            } else if (this._accumulatedWheelDeltaX > 0) {
                this._handleMouseButton(pos.x, pos.y, bmask | 1 << 6);
                this._handleMouseButton(pos.x, pos.y, bmask);
            }

            this._accumulatedWheelDeltaX = 0;
        }
        if (Math.abs(this._accumulatedWheelDeltaY) >= WHEEL_STEP) {
            if (this._accumulatedWheelDeltaY < 0) {
                this._handleMouseButton(pos.x, pos.y, bmask | 1 << 3);
                this._handleMouseButton(pos.x, pos.y, bmask);
            } else if (this._accumulatedWheelDeltaY > 0) {
                this._handleMouseButton(pos.x, pos.y, bmask | 1 << 4);
                this._handleMouseButton(pos.x, pos.y, bmask);
            }

            this._accumulatedWheelDeltaY = 0;
        }
    }

    _fakeMouseMove(ev, elementX, elementY) {
        this._handleMouseMove(elementX, elementY);
        this._cursor.move(ev.detail.clientX, ev.detail.clientY);
    }

    _handleTapEvent(ev, bmask) {
        let pos = clientToElement(ev.detail.clientX, ev.detail.clientY,
                                  this._canvas);

        // If the user quickly taps multiple times we assume they meant to
        // hit the same spot, so slightly adjust coordinates

        if ((this._gestureLastTapTime !== null) &&
            ((Date.now() - this._gestureLastTapTime) < DOUBLE_TAP_TIMEOUT) &&
            (this._gestureFirstDoubleTapEv.detail.type === ev.detail.type)) {
            let dx = this._gestureFirstDoubleTapEv.detail.clientX - ev.detail.clientX;
            let dy = this._gestureFirstDoubleTapEv.detail.clientY - ev.detail.clientY;
            let distance = Math.hypot(dx, dy);

            if (distance < DOUBLE_TAP_THRESHOLD) {
                pos = clientToElement(this._gestureFirstDoubleTapEv.detail.clientX,
                                      this._gestureFirstDoubleTapEv.detail.clientY,
                                      this._canvas);
            } else {
                this._gestureFirstDoubleTapEv = ev;
            }
        } else {
            this._gestureFirstDoubleTapEv = ev;
        }
        this._gestureLastTapTime = Date.now();

        this._fakeMouseMove(this._gestureFirstDoubleTapEv, pos.x, pos.y);
        this._handleMouseButton(pos.x, pos.y, bmask);
        this._handleMouseButton(pos.x, pos.y, 0x0);
    }

    _handleGesture(ev) {
        let magnitude;

        let pos = clientToElement(ev.detail.clientX, ev.detail.clientY,
                                  this._canvas);
        switch (ev.type) {
            case 'gesturestart':
                switch (ev.detail.type) {
                    case 'onetap':
                        this._handleTapEvent(ev, 0x1);
                        break;
                    case 'twotap':
                        this._handleTapEvent(ev, 0x4);
                        break;
                    case 'threetap':
                        this._handleTapEvent(ev, 0x2);
                        break;
                    case 'drag':
                        if (this.dragViewport) {
                            this._viewportHasMoved = false;
                            this._viewportDragging = true;
                            this._viewportDragPos = {'x': pos.x, 'y': pos.y};
                        } else {
                            this._fakeMouseMove(ev, pos.x, pos.y);
                            this._handleMouseButton(pos.x, pos.y, 0x1);
                        }
                        break;
                    case 'longpress':
                        if (this.dragViewport) {
                            // If dragViewport is true, we need to wait to see
                            // if we have dragged outside the threshold before
                            // sending any events to the server.
                            this._viewportHasMoved = false;
                            this._viewportDragPos = {'x': pos.x, 'y': pos.y};
                        } else {
                            this._fakeMouseMove(ev, pos.x, pos.y);
                            this._handleMouseButton(pos.x, pos.y, 0x4);
                        }
                        break;
                    case 'twodrag':
                        this._gestureLastMagnitudeX = ev.detail.magnitudeX;
                        this._gestureLastMagnitudeY = ev.detail.magnitudeY;
                        this._fakeMouseMove(ev, pos.x, pos.y);
                        break;
                    case 'pinch':
                        this._gestureLastMagnitudeX = Math.hypot(ev.detail.magnitudeX,
                                                                 ev.detail.magnitudeY);
                        this._fakeMouseMove(ev, pos.x, pos.y);
                        break;
                }
                break;

            case 'gesturemove':
                switch (ev.detail.type) {
                    case 'onetap':
                    case 'twotap':
                    case 'threetap':
                        break;
                    case 'drag':
                    case 'longpress':
                        if (this.dragViewport) {
                            this._viewportDragging = true;
                            const deltaX = this._viewportDragPos.x - pos.x;
                            const deltaY = this._viewportDragPos.y - pos.y;

                            if (this._viewportHasMoved || (Math.abs(deltaX) > dragThreshold ||
                                                           Math.abs(deltaY) > dragThreshold)) {
                                this._viewportHasMoved = true;

                                this._viewportDragPos = {'x': pos.x, 'y': pos.y};
                                this._display.viewportChangePos(deltaX, deltaY);
                            }
                        } else {
                            this._fakeMouseMove(ev, pos.x, pos.y);
                        }
                        break;
                    case 'twodrag':
                        // Always scroll in the same position.
                        // We don't know if the mouse was moved so we need to move it
                        // every update.
                        this._fakeMouseMove(ev, pos.x, pos.y);
                        while ((ev.detail.magnitudeY - this._gestureLastMagnitudeY) > GESTURE_SCRLSENS) {
                            this._handleMouseButton(pos.x, pos.y, 0x8);
                            this._handleMouseButton(pos.x, pos.y, 0x0);
                            this._gestureLastMagnitudeY += GESTURE_SCRLSENS;
                        }
                        while ((ev.detail.magnitudeY - this._gestureLastMagnitudeY) < -GESTURE_SCRLSENS) {
                            this._handleMouseButton(pos.x, pos.y, 0x10);
                            this._handleMouseButton(pos.x, pos.y, 0x0);
                            this._gestureLastMagnitudeY -= GESTURE_SCRLSENS;
                        }
                        while ((ev.detail.magnitudeX - this._gestureLastMagnitudeX) > GESTURE_SCRLSENS) {
                            this._handleMouseButton(pos.x, pos.y, 0x20);
                            this._handleMouseButton(pos.x, pos.y, 0x0);
                            this._gestureLastMagnitudeX += GESTURE_SCRLSENS;
                        }
                        while ((ev.detail.magnitudeX - this._gestureLastMagnitudeX) < -GESTURE_SCRLSENS) {
                            this._handleMouseButton(pos.x, pos.y, 0x40);
                            this._handleMouseButton(pos.x, pos.y, 0x0);
                            this._gestureLastMagnitudeX -= GESTURE_SCRLSENS;
                        }
                        break;
                    case 'pinch':
                        // Always scroll in the same position.
                        // We don't know if the mouse was moved so we need to move it
                        // every update.
                        this._fakeMouseMove(ev, pos.x, pos.y);
                        magnitude = Math.hypot(ev.detail.magnitudeX, ev.detail.magnitudeY);
                        if (Math.abs(magnitude - this._gestureLastMagnitudeX) > GESTURE_ZOOMSENS) {
                            this._handleKeyEvent(KeyTable.XK_Control_L, "ControlLeft", true);
                            while ((magnitude - this._gestureLastMagnitudeX) > GESTURE_ZOOMSENS) {
                                this._handleMouseButton(pos.x, pos.y, 0x8);
                                this._handleMouseButton(pos.x, pos.y, 0x0);
                                this._gestureLastMagnitudeX += GESTURE_ZOOMSENS;
                            }
                            while ((magnitude -  this._gestureLastMagnitudeX) < -GESTURE_ZOOMSENS) {
                                this._handleMouseButton(pos.x, pos.y, 0x10);
                                this._handleMouseButton(pos.x, pos.y, 0x0);
                                this._gestureLastMagnitudeX -= GESTURE_ZOOMSENS;
                            }
                        }
                        this._handleKeyEvent(KeyTable.XK_Control_L, "ControlLeft", false);
                        break;
                }
                break;

            case 'gestureend':
                switch (ev.detail.type) {
                    case 'onetap':
                    case 'twotap':
                    case 'threetap':
                    case 'pinch':
                    case 'twodrag':
                        break;
                    case 'drag':
                        if (this.dragViewport) {
                            this._viewportDragging = false;
                        } else {
                            this._fakeMouseMove(ev, pos.x, pos.y);
                            this._handleMouseButton(pos.x, pos.y, 0x0);
                        }
                        break;
                    case 'longpress':
                        if (this._viewportHasMoved) {
                            // We don't want to send any events if we have moved
                            // our viewport
                            break;
                        }

                        if (this.dragViewport && !this._viewportHasMoved) {
                            this._fakeMouseMove(ev, pos.x, pos.y);
                            // If dragViewport is true, we need to wait to see
                            // if we have dragged outside the threshold before
                            // sending any events to the server.
                            this._handleMouseButton(pos.x, pos.y, 0x4);
                            this._handleMouseButton(pos.x, pos.y, 0x0);
                            this._viewportDragging = false;
                        } else {
                            this._fakeMouseMove(ev, pos.x, pos.y);
                            this._handleMouseButton(pos.x, pos.y, 0x0);
                        }
                        break;
                }
                break;
        }
    }

    _flushMouseMoveTimer(x, y) {
        if (this._mouseMoveTimer !== null) {
            clearTimeout(this._mouseMoveTimer);
            this._mouseMoveTimer = null;
            this._sendMouse(x, y, this._mouseButtonMask);
        }
    }

    // Message handlers

    _negotiateProtocolVersion() {
        if (this._sock.rQwait("version", 12)) {
            return false;
        }

        const sversion = this._sock.rQshiftStr(12).substr(4, 7);
        Log.Info("Server ProtocolVersion: " + sversion);
        let isRepeater = 0;
        switch (sversion) {
            case "000.000":  // UltraVNC repeater
                isRepeater = 1;
                break;
            case "003.003":
            case "003.006":  // UltraVNC
                this._rfbVersion = 3.3;
                break;
            case "003.007":
                this._rfbVersion = 3.7;
                break;
            case "003.008":
            case "003.889":  // Apple Remote Desktop
            case "004.000":  // Intel AMT KVM
            case "004.001":  // RealVNC 4.6
            case "005.000":  // RealVNC 5.3
                this._rfbVersion = 3.8;
                break;
            default:
                return this._fail("Invalid server version " + sversion);
        }

        if (isRepeater) {
            let repeaterID = "ID:" + this._repeaterID;
            while (repeaterID.length < 250) {
                repeaterID += "\0";
            }
            this._sock.sQpushString(repeaterID);
            this._sock.flush();
            return true;
        }

        if (this._rfbVersion > this._rfbMaxVersion) {
            this._rfbVersion = this._rfbMaxVersion;
        }

        const cversion = "00" + parseInt(this._rfbVersion, 10) +
                       ".00" + ((this._rfbVersion * 10) % 10);
        this._sock.sQpushString("RFB " + cversion + "\n");
        this._sock.flush();
        Log.Debug('Sent ProtocolVersion: ' + cversion);

        this._rfbInitState = 'Security';
    }

    _isSupportedSecurityType(type) {
        const clientTypes = [
            securityTypeNone,
            securityTypeVNCAuth,
            securityTypeRA2ne,
            securityTypeTight,
            securityTypeVeNCrypt,
            securityTypeXVP,
            securityTypeARD,
            securityTypeMSLogonII,
            securityTypePlain,
        ];

        return clientTypes.includes(type);
    }

    _negotiateSecurity() {
        if (this._rfbVersion >= 3.7) {
            // Server sends supported list, client decides
            const numTypes = this._sock.rQshift8();
            if (this._sock.rQwait("security type", numTypes, 1)) { return false; }

            if (numTypes === 0) {
                this._rfbInitState = "SecurityReason";
                this._securityContext = "no security types";
                this._securityStatus = 1;
                return true;
            }

            const types = this._sock.rQshiftBytes(numTypes);
            Log.Debug("Server security types: " + types);

            // Look for a matching security type in the order that the
            // server prefers
            this._rfbAuthScheme = -1;
            for (let type of types) {
                if (this._isSupportedSecurityType(type)) {
                    this._rfbAuthScheme = type;
                    break;
                }
            }

            if (this._rfbAuthScheme === -1) {
                return this._fail("Unsupported security types (types: " + types + ")");
            }

            this._sock.sQpush8(this._rfbAuthScheme);
            this._sock.flush();
        } else {
            // Server decides
            if (this._sock.rQwait("security scheme", 4)) { return false; }
            this._rfbAuthScheme = this._sock.rQshift32();

            if (this._rfbAuthScheme == 0) {
                this._rfbInitState = "SecurityReason";
                this._securityContext = "authentication scheme";
                this._securityStatus = 1;
                return true;
            }
        }

        this._rfbInitState = 'Authentication';
        Log.Debug('Authenticating using scheme: ' + this._rfbAuthScheme);

        return true;
    }

    _handleSecurityReason() {
        if (this._sock.rQwait("reason length", 4)) {
            return false;
        }
        const strlen = this._sock.rQshift32();
        let reason = "";

        if (strlen > 0) {
            if (this._sock.rQwait("reason", strlen, 4)) { return false; }
            reason = this._sock.rQshiftStr(strlen);
        }

        if (reason !== "") {
            this.dispatchEvent(new CustomEvent(
                "securityfailure",
                { detail: { status: this._securityStatus,
                            reason: reason } }));

            return this._fail("Security negotiation failed on " +
                              this._securityContext +
                              " (reason: " + reason + ")");
        } else {
            this.dispatchEvent(new CustomEvent(
                "securityfailure",
                { detail: { status: this._securityStatus } }));

            return this._fail("Security negotiation failed on " +
                              this._securityContext);
        }
    }

    // authentication
    _negotiateXvpAuth() {
        if (this._rfbCredentials.username === undefined ||
            this._rfbCredentials.password === undefined ||
            this._rfbCredentials.target === undefined) {
            this.dispatchEvent(new CustomEvent(
                "credentialsrequired",
                { detail: { types: ["username", "password", "target"] } }));
            return false;
        }

        this._sock.sQpush8(this._rfbCredentials.username.length);
        this._sock.sQpush8(this._rfbCredentials.target.length);
        this._sock.sQpushString(this._rfbCredentials.username);
        this._sock.sQpushString(this._rfbCredentials.target);

        this._sock.flush();

        this._rfbAuthScheme = securityTypeVNCAuth;

        return this._negotiateAuthentication();
    }

    // VeNCrypt authentication, currently only supports version 0.2 and only Plain subtype
    _negotiateVeNCryptAuth() {

        // waiting for VeNCrypt version
        if (this._rfbVeNCryptState == 0) {
            if (this._sock.rQwait("vencrypt version", 2)) { return false; }

            const major = this._sock.rQshift8();
            const minor = this._sock.rQshift8();

            if (!(major == 0 && minor == 2)) {
                return this._fail("Unsupported VeNCrypt version " + major + "." + minor);
            }

            this._sock.sQpush8(0);
            this._sock.sQpush8(2);
            this._sock.flush();
            this._rfbVeNCryptState = 1;
        }

        // waiting for ACK
        if (this._rfbVeNCryptState == 1) {
            if (this._sock.rQwait("vencrypt ack", 1)) { return false; }

            const res = this._sock.rQshift8();

            if (res != 0) {
                return this._fail("VeNCrypt failure " + res);
            }

            this._rfbVeNCryptState = 2;
        }
        // must fall through here (i.e. no "else if"), beacause we may have already received
        // the subtypes length and won't be called again

        if (this._rfbVeNCryptState == 2) { // waiting for subtypes length
            if (this._sock.rQwait("vencrypt subtypes length", 1)) { return false; }

            const subtypesLength = this._sock.rQshift8();
            if (subtypesLength < 1) {
                return this._fail("VeNCrypt subtypes empty");
            }

            this._rfbVeNCryptSubtypesLength = subtypesLength;
            this._rfbVeNCryptState = 3;
        }

        // waiting for subtypes list
        if (this._rfbVeNCryptState == 3) {
            if (this._sock.rQwait("vencrypt subtypes", 4 * this._rfbVeNCryptSubtypesLength)) { return false; }

            const subtypes = [];
            for (let i = 0; i < this._rfbVeNCryptSubtypesLength; i++) {
                subtypes.push(this._sock.rQshift32());
            }

            // Look for a matching security type in the order that the
            // server prefers
            this._rfbAuthScheme = -1;
            for (let type of subtypes) {
                // Avoid getting in to a loop
                if (type === securityTypeVeNCrypt) {
                    continue;
                }

                if (this._isSupportedSecurityType(type)) {
                    this._rfbAuthScheme = type;
                    break;
                }
            }

            if (this._rfbAuthScheme === -1) {
                return this._fail("Unsupported security types (types: " + subtypes + ")");
            }

            this._sock.sQpush32(this._rfbAuthScheme);
            this._sock.flush();

            this._rfbVeNCryptState = 4;
            return true;
        }
    }

    _negotiatePlainAuth() {
        if (this._rfbCredentials.username === undefined ||
            this._rfbCredentials.password === undefined) {
            this.dispatchEvent(new CustomEvent(
                "credentialsrequired",
                { detail: { types: ["username", "password"] } }));
            return false;
        }

        const user = encodeUTF8(this._rfbCredentials.username);
        const pass = encodeUTF8(this._rfbCredentials.password);

        this._sock.sQpush32(user.length);
        this._sock.sQpush32(pass.length);
        this._sock.sQpushString(user);
        this._sock.sQpushString(pass);
        this._sock.flush();

        this._rfbInitState = "SecurityResult";
        return true;
    }

    _negotiateStdVNCAuth() {
        if (this._sock.rQwait("auth challenge", 16)) { return false; }

        if (this._rfbCredentials.password === undefined) {
            this.dispatchEvent(new CustomEvent(
                "credentialsrequired",
                { detail: { types: ["password"] } }));
            return false;
        }

        // TODO(directxman12): make genDES not require an Array
        const challenge = Array.prototype.slice.call(this._sock.rQshiftBytes(16));
        const response = RFB.genDES(this._rfbCredentials.password, challenge);
        this._sock.sQpushBytes(response);
        this._sock.flush();
        this._rfbInitState = "SecurityResult";
        return true;
    }

    _negotiateARDAuth() {

        if (this._rfbCredentials.username === undefined ||
            this._rfbCredentials.password === undefined) {
            this.dispatchEvent(new CustomEvent(
                "credentialsrequired",
                { detail: { types: ["username", "password"] } }));
            return false;
        }

        if (this._rfbCredentials.ardPublicKey != undefined &&
            this._rfbCredentials.ardCredentials != undefined) {
            // if the async web crypto is done return the results
            this._sock.sQpushBytes(this._rfbCredentials.ardCredentials);
            this._sock.sQpushBytes(this._rfbCredentials.ardPublicKey);
            this._sock.flush();
            this._rfbCredentials.ardCredentials = null;
            this._rfbCredentials.ardPublicKey = null;
            this._rfbInitState = "SecurityResult";
            return true;
        }

        if (this._sock.rQwait("read ard", 4)) { return false; }

        let generator = this._sock.rQshiftBytes(2);   // DH base generator value

        let keyLength = this._sock.rQshift16();

        if (this._sock.rQwait("read ard keylength", keyLength*2, 4)) { return false; }

        // read the server values
        let prime = this._sock.rQshiftBytes(keyLength);  // predetermined prime modulus
        let serverPublicKey = this._sock.rQshiftBytes(keyLength); // other party's public key

        let clientKey = legacyCrypto.generateKey(
            { name: "DH", g: generator, p: prime }, false, ["deriveBits"]);
        this._negotiateARDAuthAsync(keyLength, serverPublicKey, clientKey);

        return false;
    }

    async _negotiateARDAuthAsync(keyLength, serverPublicKey, clientKey) {
        const clientPublicKey = legacyCrypto.exportKey("raw", clientKey.publicKey);
        const sharedKey = legacyCrypto.deriveBits(
            { name: "DH", public: serverPublicKey }, clientKey.privateKey, keyLength * 8);

        const username = encodeUTF8(this._rfbCredentials.username).substring(0, 63);
        const password = encodeUTF8(this._rfbCredentials.password).substring(0, 63);

        const credentials = window.crypto.getRandomValues(new Uint8Array(128));
        for (let i = 0; i < username.length; i++) {
            credentials[i] = username.charCodeAt(i);
        }
        credentials[username.length] = 0;
        for (let i = 0; i < password.length; i++) {
            credentials[64 + i] = password.charCodeAt(i);
        }
        credentials[64 + password.length] = 0;

        const key = await legacyCrypto.digest("MD5", sharedKey);
        const cipher = await legacyCrypto.importKey(
            "raw", key, { name: "AES-ECB" }, false, ["encrypt"]);
        const encrypted = await legacyCrypto.encrypt({ name: "AES-ECB" }, cipher, credentials);

        this._rfbCredentials.ardCredentials = encrypted;
        this._rfbCredentials.ardPublicKey = clientPublicKey;

        this._resumeAuthentication();
    }

    _negotiateTightUnixAuth() {
        if (this._rfbCredentials.username === undefined ||
            this._rfbCredentials.password === undefined) {
            this.dispatchEvent(new CustomEvent(
                "credentialsrequired",
                { detail: { types: ["username", "password"] } }));
            return false;
        }

        this._sock.sQpush32(this._rfbCredentials.username.length);
        this._sock.sQpush32(this._rfbCredentials.password.length);
        this._sock.sQpushString(this._rfbCredentials.username);
        this._sock.sQpushString(this._rfbCredentials.password);
        this._sock.flush();

        this._rfbInitState = "SecurityResult";
        return true;
    }

    _negotiateTightTunnels(numTunnels) {
        const clientSupportedTunnelTypes = {
            0: { vendor: 'TGHT', signature: 'NOTUNNEL' }
        };
        const serverSupportedTunnelTypes = {};
        // receive tunnel capabilities
        for (let i = 0; i < numTunnels; i++) {
            const capCode = this._sock.rQshift32();
            const capVendor = this._sock.rQshiftStr(4);
            const capSignature = this._sock.rQshiftStr(8);
            serverSupportedTunnelTypes[capCode] = { vendor: capVendor, signature: capSignature };
        }

        Log.Debug("Server Tight tunnel types: " + serverSupportedTunnelTypes);

        // Siemens touch panels have a VNC server that supports NOTUNNEL,
        // but forgets to advertise it. Try to detect such servers by
        // looking for their custom tunnel type.
        if (serverSupportedTunnelTypes[1] &&
            (serverSupportedTunnelTypes[1].vendor === "SICR") &&
            (serverSupportedTunnelTypes[1].signature === "SCHANNEL")) {
            Log.Debug("Detected Siemens server. Assuming NOTUNNEL support.");
            serverSupportedTunnelTypes[0] = { vendor: 'TGHT', signature: 'NOTUNNEL' };
        }

        // choose the notunnel type
        if (serverSupportedTunnelTypes[0]) {
            if (serverSupportedTunnelTypes[0].vendor != clientSupportedTunnelTypes[0].vendor ||
                serverSupportedTunnelTypes[0].signature != clientSupportedTunnelTypes[0].signature) {
                return this._fail("Client's tunnel type had the incorrect " +
                                  "vendor or signature");
            }
            Log.Debug("Selected tunnel type: " + clientSupportedTunnelTypes[0]);
            this._sock.sQpush32(0); // use NOTUNNEL
            this._sock.flush();
            return false; // wait until we receive the sub auth count to continue
        } else {
            return this._fail("Server wanted tunnels, but doesn't support " +
                              "the notunnel type");
        }
    }

    _negotiateTightAuth() {
        if (!this._rfbTightVNC) {  // first pass, do the tunnel negotiation
            if (this._sock.rQwait("num tunnels", 4)) { return false; }
            const numTunnels = this._sock.rQshift32();
            if (numTunnels > 0 && this._sock.rQwait("tunnel capabilities", 16 * numTunnels, 4)) { return false; }

            this._rfbTightVNC = true;

            if (numTunnels > 0) {
                this._negotiateTightTunnels(numTunnels);
                return false;  // wait until we receive the sub auth to continue
            }
        }

        // second pass, do the sub-auth negotiation
        if (this._sock.rQwait("sub auth count", 4)) { return false; }
        const subAuthCount = this._sock.rQshift32();
        if (subAuthCount === 0) {  // empty sub-auth list received means 'no auth' subtype selected
            this._rfbInitState = 'SecurityResult';
            return true;
        }

        if (this._sock.rQwait("sub auth capabilities", 16 * subAuthCount, 4)) { return false; }

        const clientSupportedTypes = {
            'STDVNOAUTH__': 1,
            'STDVVNCAUTH_': 2,
            'TGHTULGNAUTH': 129
        };

        const serverSupportedTypes = [];

        for (let i = 0; i < subAuthCount; i++) {
            this._sock.rQshift32(); // capNum
            const capabilities = this._sock.rQshiftStr(12);
            serverSupportedTypes.push(capabilities);
        }

        Log.Debug("Server Tight authentication types: " + serverSupportedTypes);

        for (let authType in clientSupportedTypes) {
            if (serverSupportedTypes.indexOf(authType) != -1) {
                this._sock.sQpush32(clientSupportedTypes[authType]);
                this._sock.flush();
                Log.Debug("Selected authentication type: " + authType);

                switch (authType) {
                    case 'STDVNOAUTH__':  // no auth
                        this._rfbInitState = 'SecurityResult';
                        return true;
                    case 'STDVVNCAUTH_':
                        this._rfbAuthScheme = securityTypeVNCAuth;
                        return true;
                    case 'TGHTULGNAUTH':
                        this._rfbAuthScheme = securityTypeUnixLogon;
                        return true;
                    default:
                        return this._fail("Unsupported tiny auth scheme " +
                                          "(scheme: " + authType + ")");
                }
            }
        }

        return this._fail("No supported sub-auth types!");
    }

    _handleRSAAESCredentialsRequired(event) {
        this.dispatchEvent(event);
    }

    _handleRSAAESServerVerification(event) {
        this.dispatchEvent(event);
    }

    _negotiateRA2neAuth() {
        if (this._rfbRSAAESAuthenticationState === null) {
            this._rfbRSAAESAuthenticationState = new RSAAESAuthenticationState(this._sock, () => this._rfbCredentials);
            this._rfbRSAAESAuthenticationState.addEventListener(
                "serververification", this._eventHandlers.handleRSAAESServerVerification);
            this._rfbRSAAESAuthenticationState.addEventListener(
                "credentialsrequired", this._eventHandlers.handleRSAAESCredentialsRequired);
        }
        this._rfbRSAAESAuthenticationState.checkInternalEvents();
        if (!this._rfbRSAAESAuthenticationState.hasStarted) {
            this._rfbRSAAESAuthenticationState.negotiateRA2neAuthAsync()
                .catch((e) => {
                    if (e.message !== "disconnect normally") {
                        this._fail(e.message);
                    }
                })
                .then(() => {
                    this._rfbInitState = "SecurityResult";
                    return true;
                }).finally(() => {
                    this._rfbRSAAESAuthenticationState.removeEventListener(
                        "serververification", this._eventHandlers.handleRSAAESServerVerification);
                    this._rfbRSAAESAuthenticationState.removeEventListener(
                        "credentialsrequired", this._eventHandlers.handleRSAAESCredentialsRequired);
                    this._rfbRSAAESAuthenticationState = null;
                });
        }
        return false;
    }

    _negotiateMSLogonIIAuth() {
        if (this._sock.rQwait("mslogonii dh param", 24)) { return false; }

        if (this._rfbCredentials.username === undefined ||
            this._rfbCredentials.password === undefined) {
            this.dispatchEvent(new CustomEvent(
                "credentialsrequired",
                { detail: { types: ["username", "password"] } }));
            return false;
        }

        const g = this._sock.rQshiftBytes(8);
        const p = this._sock.rQshiftBytes(8);
        const A = this._sock.rQshiftBytes(8);
        const dhKey = legacyCrypto.generateKey({ name: "DH", g: g, p: p }, true, ["deriveBits"]);
        const B = legacyCrypto.exportKey("raw", dhKey.publicKey);
        const secret = legacyCrypto.deriveBits({ name: "DH", public: A }, dhKey.privateKey, 64);

        const key = legacyCrypto.importKey("raw", secret, { name: "DES-CBC" }, false, ["encrypt"]);
        const username = encodeUTF8(this._rfbCredentials.username).substring(0, 255);
        const password = encodeUTF8(this._rfbCredentials.password).substring(0, 63);
        let usernameBytes = new Uint8Array(256);
        let passwordBytes = new Uint8Array(64);
        window.crypto.getRandomValues(usernameBytes);
        window.crypto.getRandomValues(passwordBytes);
        for (let i = 0; i < username.length; i++) {
            usernameBytes[i] = username.charCodeAt(i);
        }
        usernameBytes[username.length] = 0;
        for (let i = 0; i < password.length; i++) {
            passwordBytes[i] = password.charCodeAt(i);
        }
        passwordBytes[password.length] = 0;
        usernameBytes = legacyCrypto.encrypt({ name: "DES-CBC", iv: secret }, key, usernameBytes);
        passwordBytes = legacyCrypto.encrypt({ name: "DES-CBC", iv: secret }, key, passwordBytes);
        this._sock.sQpushBytes(B);
        this._sock.sQpushBytes(usernameBytes);
        this._sock.sQpushBytes(passwordBytes);
        this._sock.flush();
        this._rfbInitState = "SecurityResult";
        return true;
    }

    _negotiateAuthentication() {
        switch (this._rfbAuthScheme) {
            case securityTypeNone:
                if (this._rfbVersion >= 3.8) {
                    this._rfbInitState = 'SecurityResult';
                } else {
                    this._rfbInitState = 'ClientInitialisation';
                }
                return true;

            case securityTypeXVP:
                return this._negotiateXvpAuth();

            case securityTypeARD:
                return this._negotiateARDAuth();

            case securityTypeVNCAuth:
                return this._negotiateStdVNCAuth();

            case securityTypeTight:
                return this._negotiateTightAuth();

            case securityTypeVeNCrypt:
                return this._negotiateVeNCryptAuth();

            case securityTypePlain:
                return this._negotiatePlainAuth();

            case securityTypeUnixLogon:
                return this._negotiateTightUnixAuth();

            case securityTypeRA2ne:
                return this._negotiateRA2neAuth();

            case securityTypeMSLogonII:
                return this._negotiateMSLogonIIAuth();

            default:
                return this._fail("Unsupported auth scheme (scheme: " +
                                  this._rfbAuthScheme + ")");
        }
    }

    _handleSecurityResult() {
        if (this._sock.rQwait('VNC auth response ', 4)) { return false; }

        const status = this._sock.rQshift32();

        if (status === 0) { // OK
            this._rfbInitState = 'ClientInitialisation';
            Log.Debug('Authentication OK');
            return true;
        } else {
            if (this._rfbVersion >= 3.8) {
                this._rfbInitState = "SecurityReason";
                this._securityContext = "security result";
                this._securityStatus = status;
                return true;
            } else {
                this.dispatchEvent(new CustomEvent(
                    "securityfailure",
                    { detail: { status: status } }));

                return this._fail("Security handshake failed");
            }
        }
    }

    _negotiateServerInit() {
        if (this._sock.rQwait("server initialization", 24)) { return false; }

        /* Screen size */
        const width = this._sock.rQshift16();
        const height = this._sock.rQshift16();

        /* PIXEL_FORMAT */
        const bpp         = this._sock.rQshift8();
        const depth       = this._sock.rQshift8();
        const bigEndian  = this._sock.rQshift8();
        const trueColor  = this._sock.rQshift8();

        const redMax     = this._sock.rQshift16();
        const greenMax   = this._sock.rQshift16();
        const blueMax    = this._sock.rQshift16();
        const redShift   = this._sock.rQshift8();
        const greenShift = this._sock.rQshift8();
        const blueShift  = this._sock.rQshift8();
        this._sock.rQskipBytes(3);  // padding

        // NB(directxman12): we don't want to call any callbacks or print messages until
        //                   *after* we're past the point where we could backtrack

        /* Connection name/title */
        const nameLength = this._sock.rQshift32();
        if (this._sock.rQwait('server init name', nameLength, 24)) { return false; }
        let name = this._sock.rQshiftStr(nameLength);
        name = decodeUTF8(name, true);

        if (this._rfbTightVNC) {
            if (this._sock.rQwait('TightVNC extended server init header', 8, 24 + nameLength)) { return false; }
            // In TightVNC mode, ServerInit message is extended
            const numServerMessages = this._sock.rQshift16();
            const numClientMessages = this._sock.rQshift16();
            const numEncodings = this._sock.rQshift16();
            this._sock.rQskipBytes(2);  // padding

            const totalMessagesLength = (numServerMessages + numClientMessages + numEncodings) * 16;
            if (this._sock.rQwait('TightVNC extended server init header', totalMessagesLength, 32 + nameLength)) { return false; }

            // we don't actually do anything with the capability information that TIGHT sends,
            // so we just skip the all of this.

            // TIGHT server message capabilities
            this._sock.rQskipBytes(16 * numServerMessages);

            // TIGHT client message capabilities
            this._sock.rQskipBytes(16 * numClientMessages);

            // TIGHT encoding capabilities
            this._sock.rQskipBytes(16 * numEncodings);
        }

        // NB(directxman12): these are down here so that we don't run them multiple times
        //                   if we backtrack
        Log.Info("Screen: " + width + "x" + height +
                  ", bpp: " + bpp + ", depth: " + depth +
                  ", bigEndian: " + bigEndian +
                  ", trueColor: " + trueColor +
                  ", redMax: " + redMax +
                  ", greenMax: " + greenMax +
                  ", blueMax: " + blueMax +
                  ", redShift: " + redShift +
                  ", greenShift: " + greenShift +
                  ", blueShift: " + blueShift);

        // we're past the point where we could backtrack, so it's safe to call this
        this._setDesktopName(name);
        Log.Info("Connected to server: '" + this._fbName + "'");
        this._resize(width, height);

        if (!this._viewOnly) { this._keyboard.grab(); }

        this._fbDepth = 24;
        this._BGRmode = false;

        if (this._fbName === "Intel(r) AMT KVM") {
            Log.Warn("Intel AMT KVM only supports 8/16 bit depths. Using low color mode.");
            this._fbDepth = 8;
        } else if (this._fbName === "Qt for Embedded Linux VNC Server" || 
                   this._fbName.indexOf("Qt") !== -1) {
            // Qt has a bug (as of QT 6.4) where, if the endian-ness is 'little' and the _fbDepth is 24, it does not honour the noVNC reqested 
            // redshift/blueshift values. In these conditions it triggers a performance bypass in the Qt code which just uses the raw
            // Qt frambuffer byte order (https://github.com/qt/qtbase/blob/5.15.2/src/plugins/platforms/vnc/qvncclient.cpp#L113) which is BGR
            // vs the RGB noVNC wants. Since noVNC always operates in little endian and fbDepth 24, it always triggers this bug
            // So, for Qt we change to BGR ordering. Note that Qt only uses raw encoding and noVNC only supports this mode in the raw decoder
            Log.Info("Detected Qt VNC server. Enabling BGR color mode.");
            this._BGRmode = true;
        }

        RFB.messages.pixelFormat(this._sock, this._fbDepth, true, this._BGRmode);
        this._sendEncodings();
        RFB.messages.fbUpdateRequest(this._sock, false, 0, 0, this._fbWidth, this._fbHeight);

        this._updateConnectionState('connected');
        return true;
    }

    _sendEncodings() {
        const encs = [];

        // In preference order
        encs.push(encodings.encodingCopyRect);
        // Only supported with full depth support
        if (this._fbDepth == 24) {
            if (supportsWebCodecsH264Decode) {
                encs.push(encodings.encodingH264);
            }
            encs.push(encodings.encodingTight);
            encs.push(encodings.encodingTightPNG);
            encs.push(encodings.encodingZRLE);
            encs.push(encodings.encodingJPEG);
            encs.push(encodings.encodingHextile);
            encs.push(encodings.encodingRRE);
            encs.push(encodings.encodingZlib);
        }
        encs.push(encodings.encodingRaw);

        // Psuedo-encoding settings
        encs.push(encodings.pseudoEncodingQualityLevel0 + this._qualityLevel);
        encs.push(encodings.pseudoEncodingCompressLevel0 + this._compressionLevel);

        encs.push(encodings.pseudoEncodingDesktopSize);
        encs.push(encodings.pseudoEncodingLastRect);
        encs.push(encodings.pseudoEncodingQEMUExtendedKeyEvent);
        encs.push(encodings.pseudoEncodingQEMULedEvent);
        encs.push(encodings.pseudoEncodingExtendedDesktopSize);
        encs.push(encodings.pseudoEncodingXvp);
        encs.push(encodings.pseudoEncodingFence);
        encs.push(encodings.pseudoEncodingContinuousUpdates);
        encs.push(encodings.pseudoEncodingDesktopName);
        encs.push(encodings.pseudoEncodingExtendedClipboard);
        encs.push(encodings.pseudoEncodingExtendedMouseButtons);

        if (this._fbDepth == 24) {
            encs.push(encodings.pseudoEncodingVMwareCursor);
            encs.push(encodings.pseudoEncodingCursor);
        }

        RFB.messages.clientEncodings(this._sock, encs);
    }

    /* RFB protocol initialization states:
     *   ProtocolVersion
     *   Security
     *   Authentication
     *   SecurityResult
     *   ClientInitialization - not triggered by server message
     *   ServerInitialization
     */
    _initMsg() {
        switch (this._rfbInitState) {
            case 'ProtocolVersion':
                return this._negotiateProtocolVersion();

            case 'Security':
                return this._negotiateSecurity();

            case 'Authentication':
                return this._negotiateAuthentication();

            case 'SecurityResult':
                return this._handleSecurityResult();

            case 'SecurityReason':
                return this._handleSecurityReason();

            case 'ClientInitialisation':
                this._sock.sQpush8(this._shared ? 1 : 0); // ClientInitialisation
                this._sock.flush();
                this._rfbInitState = 'ServerInitialisation';
                return true;

            case 'ServerInitialisation':
                return this._negotiateServerInit();

            default:
                return this._fail("Unknown init state (state: " +
                                  this._rfbInitState + ")");
        }
    }

    // Resume authentication handshake after it was paused for some
    // reason, e.g. waiting for a password from the user
    _resumeAuthentication() {
        // We use setTimeout() so it's run in its own context, just like
        // it originally did via the WebSocket's event handler
        setTimeout(this._initMsg.bind(this), 0);
    }

    _handleSetColourMapMsg() {
        Log.Debug("SetColorMapEntries");

        return this._fail("Unexpected SetColorMapEntries message");
    }

    _handleServerCutText() {
        Log.Debug("ServerCutText");

        if (this._sock.rQwait("ServerCutText header", 7, 1)) { return false; }

        this._sock.rQskipBytes(3);  // Padding

        let length = this._sock.rQshift32();
        length = toSigned32bit(length);

        if (this._sock.rQwait("ServerCutText content", Math.abs(length), 8)) { return false; }

        if (length >= 0) {
            //Standard msg
            const text = this._sock.rQshiftStr(length);
            if (this._viewOnly) {
                return true;
            }

            this.dispatchEvent(new CustomEvent(
                "clipboard",
                { detail: { text: text } }));

        } else {
            //Extended msg.
            length = Math.abs(length);
            const flags = this._sock.rQshift32();
            let formats = flags & 0x0000FFFF;
            let actions = flags & 0xFF000000;

            let isCaps = (!!(actions & extendedClipboardActionCaps));
            if (isCaps) {
                this._clipboardServerCapabilitiesFormats = {};
                this._clipboardServerCapabilitiesActions = {};

                // Update our server capabilities for Formats
                for (let i = 0; i <= 15; i++) {
                    let index = 1 << i;

                    // Check if format flag is set.
                    if ((formats & index)) {
                        this._clipboardServerCapabilitiesFormats[index] = true;
                        // We don't send unsolicited clipboard, so we
                        // ignore the size
                        this._sock.rQshift32();
                    }
                }

                // Update our server capabilities for Actions
                for (let i = 24; i <= 31; i++) {
                    let index = 1 << i;
                    this._clipboardServerCapabilitiesActions[index] = !!(actions & index);
                }

                /*  Caps handling done, send caps with the clients
                    capabilities set as a response */
                let clientActions = [
                    extendedClipboardActionCaps,
                    extendedClipboardActionRequest,
                    extendedClipboardActionPeek,
                    extendedClipboardActionNotify,
                    extendedClipboardActionProvide
                ];
                RFB.messages.extendedClipboardCaps(this._sock, clientActions, {extendedClipboardFormatText: 0});

            } else if (actions === extendedClipboardActionRequest) {
                if (this._viewOnly) {
                    return true;
                }

                // Check if server has told us it can handle Provide and there is clipboard data to send.
                if (this._clipboardText != null &&
                    this._clipboardServerCapabilitiesActions[extendedClipboardActionProvide]) {

                    if (formats & extendedClipboardFormatText) {
                        RFB.messages.extendedClipboardProvide(this._sock, [extendedClipboardFormatText], [this._clipboardText]);
                    }
                }

            } else if (actions === extendedClipboardActionPeek) {
                if (this._viewOnly) {
                    return true;
                }

                if (this._clipboardServerCapabilitiesActions[extendedClipboardActionNotify]) {

                    if (this._clipboardText != null) {
                        RFB.messages.extendedClipboardNotify(this._sock, [extendedClipboardFormatText]);
                    } else {
                        RFB.messages.extendedClipboardNotify(this._sock, []);
                    }
                }

            } else if (actions === extendedClipboardActionNotify) {
                if (this._viewOnly) {
                    return true;
                }

                if (this._clipboardServerCapabilitiesActions[extendedClipboardActionRequest]) {

                    if (formats & extendedClipboardFormatText) {
                        RFB.messages.extendedClipboardRequest(this._sock, [extendedClipboardFormatText]);
                    }
                }

            } else if (actions === extendedClipboardActionProvide) {
                if (this._viewOnly) {
                    return true;
                }

                if (!(formats & extendedClipboardFormatText)) {
                    return true;
                }
                // Ignore what we had in our clipboard client side.
                this._clipboardText = null;

                // FIXME: Should probably verify that this data was actually requested
                let zlibStream = this._sock.rQshiftBytes(length - 4);
                let streamInflator = new Inflator();
                let textData = null;

                streamInflator.setInput(zlibStream);
                for (let i = 0; i <= 15; i++) {
                    let format = 1 << i;

                    if (formats & format) {

                        let size = 0x00;
                        let sizeArray = streamInflator.inflate(4);

                        size |= (sizeArray[0] << 24);
                        size |= (sizeArray[1] << 16);
                        size |= (sizeArray[2] << 8);
                        size |= (sizeArray[3]);
                        let chunk = streamInflator.inflate(size);

                        if (format === extendedClipboardFormatText) {
                            textData = chunk;
                        }
                    }
                }
                streamInflator.setInput(null);

                if (textData !== null) {
                    let tmpText = "";
                    for (let i = 0; i < textData.length; i++) {
                        tmpText += String.fromCharCode(textData[i]);
                    }
                    textData = tmpText;

                    textData = decodeUTF8(textData);
                    if ((textData.length > 0) && "\0" === textData.charAt(textData.length - 1)) {
                        textData = textData.slice(0, -1);
                    }

                    textData = textData.replaceAll("\r\n", "\n");

                    this.dispatchEvent(new CustomEvent(
                        "clipboard",
                        { detail: { text: textData } }));
                }
            } else {
                return this._fail("Unexpected action in extended clipboard message: " + actions);
            }
        }
        return true;
    }

    _handleServerFenceMsg() {
        if (this._sock.rQwait("ServerFence header", 8, 1)) { return false; }
        this._sock.rQskipBytes(3); // Padding
        let flags = this._sock.rQshift32();
        let length = this._sock.rQshift8();

        if (this._sock.rQwait("ServerFence payload", length, 9)) { return false; }

        if (length > 64) {
            Log.Warn("Bad payload length (" + length + ") in fence response");
            length = 64;
        }

        const payload = this._sock.rQshiftStr(length);

        this._supportsFence = true;

        /*
         * Fence flags
         *
         *  (1<<0)  - BlockBefore
         *  (1<<1)  - BlockAfter
         *  (1<<2)  - SyncNext
         *  (1<<31) - Request
         */

        if (!(flags & (1<<31))) {
            return this._fail("Unexpected fence response");
        }

        // Filter out unsupported flags
        // FIXME: support syncNext
        flags &= (1<<0) | (1<<1);

        // BlockBefore and BlockAfter are automatically handled by
        // the fact that we process each incoming message
        // synchronuosly.
        RFB.messages.clientFence(this._sock, flags, payload);

        return true;
    }

    _handleXvpMsg() {
        if (this._sock.rQwait("XVP version and message", 3, 1)) { return false; }
        this._sock.rQskipBytes(1);  // Padding
        const xvpVer = this._sock.rQshift8();
        const xvpMsg = this._sock.rQshift8();

        switch (xvpMsg) {
            case 0:  // XVP_FAIL
                Log.Error("XVP operation failed");
                break;
            case 1:  // XVP_INIT
                this._rfbXvpVer = xvpVer;
                Log.Info("XVP extensions enabled (version " + this._rfbXvpVer + ")");
                this._setCapability("power", true);
                break;
            default:
                this._fail("Illegal server XVP message (msg: " + xvpMsg + ")");
                break;
        }

        return true;
    }

    _normalMsg() {
        let msgType;
        if (this._FBU.rects > 0) {
            msgType = 0;
        } else {
            msgType = this._sock.rQshift8();
        }

        let first, ret;
        switch (msgType) {
            case 0:  // FramebufferUpdate
                ret = this._framebufferUpdate();
                if (ret && !this._enabledContinuousUpdates) {
                    RFB.messages.fbUpdateRequest(this._sock, true, 0, 0,
                                                 this._fbWidth, this._fbHeight);
                }
                return ret;

            case 1:  // SetColorMapEntries
                return this._handleSetColourMapMsg();

            case 2:  // Bell
                Log.Debug("Bell");
                this.dispatchEvent(new CustomEvent(
                    "bell",
                    { detail: {} }));
                return true;

            case 3:  // ServerCutText
                return this._handleServerCutText();

            case 150: // EndOfContinuousUpdates
                first = !this._supportsContinuousUpdates;
                this._supportsContinuousUpdates = true;
                this._enabledContinuousUpdates = false;
                if (first) {
                    this._enabledContinuousUpdates = true;
                    this._updateContinuousUpdates();
                    Log.Info("Enabling continuous updates.");
                } else {
                    // FIXME: We need to send a framebufferupdaterequest here
                    // if we add support for turning off continuous updates
                }
                return true;

            case 248: // ServerFence
                return this._handleServerFenceMsg();

            case 250:  // XVP
                return this._handleXvpMsg();

            default:
                this._fail("Unexpected server message (type " + msgType + ")");
                Log.Debug("sock.rQpeekBytes(30): " + this._sock.rQpeekBytes(30));
                return true;
        }
    }

    _framebufferUpdate() {
        if (this._FBU.rects === 0) {
            if (this._sock.rQwait("FBU header", 3, 1)) { return false; }
            this._sock.rQskipBytes(1);  // Padding
            this._FBU.rects = this._sock.rQshift16();

            // Make sure the previous frame is fully rendered first
            // to avoid building up an excessive queue
            if (this._display.pending()) {
                this._flushing = true;
                this._display.flush()
                    .then(() => {
                        this._flushing = false;
                        // Resume processing
                        if (!this._sock.rQwait("message", 1)) {
                            this._handleMessage();
                        }
                    });
                return false;
            }
        }

        while (this._FBU.rects > 0) {
            if (this._FBU.encoding === null) {
                if (this._sock.rQwait("rect header", 12)) { return false; }
                /* New FramebufferUpdate */

                this._FBU.x = this._sock.rQshift16();
                this._FBU.y = this._sock.rQshift16();
                this._FBU.width = this._sock.rQshift16();
                this._FBU.height = this._sock.rQshift16();
                this._FBU.encoding = this._sock.rQshift32();
                /* Encodings are signed */
                this._FBU.encoding >>= 0;
            }

            if (!this._handleRect()) {
                return false;
            }

            this._FBU.rects--;
            this._FBU.encoding = null;
        }

        this._display.flip();

        return true;  // We finished this FBU
    }

    _handleRect() {
        switch (this._FBU.encoding) {
            case encodings.pseudoEncodingLastRect:
                this._FBU.rects = 1; // Will be decreased when we return
                return true;

            case encodings.pseudoEncodingVMwareCursor:
                return this._handleVMwareCursor();

            case encodings.pseudoEncodingCursor:
                return this._handleCursor();

            case encodings.pseudoEncodingQEMUExtendedKeyEvent:
                this._qemuExtKeyEventSupported = true;
                return true;

            case encodings.pseudoEncodingDesktopName:
                return this._handleDesktopName();

            case encodings.pseudoEncodingDesktopSize:
                this._resize(this._FBU.width, this._FBU.height);
                return true;

            case encodings.pseudoEncodingExtendedDesktopSize:
                return this._handleExtendedDesktopSize();

            case encodings.pseudoEncodingExtendedMouseButtons:
                this._extendedPointerEventSupported = true;
                return true;

            case encodings.pseudoEncodingQEMULedEvent:
                return this._handleLedEvent();

            default:
                return this._handleDataRect();
        }
    }

    _handleVMwareCursor() {
        const hotx = this._FBU.x;  // hotspot-x
        const hoty = this._FBU.y;  // hotspot-y
        const w = this._FBU.width;
        const h = this._FBU.height;
        if (this._sock.rQwait("VMware cursor encoding", 1)) {
            return false;
        }

        const cursorType = this._sock.rQshift8();

        this._sock.rQshift8(); //Padding

        let rgba;
        const bytesPerPixel = 4;

        //Classic cursor
        if (cursorType == 0) {
            //Used to filter away unimportant bits.
            //OR is used for correct conversion in js.
            const PIXEL_MASK = 0xffffff00 | 0;
            rgba = new Array(w * h * bytesPerPixel);

            if (this._sock.rQwait("VMware cursor classic encoding",
                                  (w * h * bytesPerPixel) * 2, 2)) {
                return false;
            }

            let andMask = new Array(w * h);
            for (let pixel = 0; pixel < (w * h); pixel++) {
                andMask[pixel] = this._sock.rQshift32();
            }

            let xorMask = new Array(w * h);
            for (let pixel = 0; pixel < (w * h); pixel++) {
                xorMask[pixel] = this._sock.rQshift32();
            }

            for (let pixel = 0; pixel < (w * h); pixel++) {
                if (andMask[pixel] == 0) {
                    //Fully opaque pixel
                    let bgr = xorMask[pixel];
                    let r   = bgr >> 8  & 0xff;
                    let g   = bgr >> 16 & 0xff;
                    let b   = bgr >> 24 & 0xff;

                    rgba[(pixel * bytesPerPixel)     ] = r;    //r
                    rgba[(pixel * bytesPerPixel) + 1 ] = g;    //g
                    rgba[(pixel * bytesPerPixel) + 2 ] = b;    //b
                    rgba[(pixel * bytesPerPixel) + 3 ] = 0xff; //a

                } else if ((andMask[pixel] & PIXEL_MASK) ==
                           PIXEL_MASK) {
                    //Only screen value matters, no mouse colouring
                    if (xorMask[pixel] == 0) {
                        //Transparent pixel
                        rgba[(pixel * bytesPerPixel)     ] = 0x00;
                        rgba[(pixel * bytesPerPixel) + 1 ] = 0x00;
                        rgba[(pixel * bytesPerPixel) + 2 ] = 0x00;
                        rgba[(pixel * bytesPerPixel) + 3 ] = 0x00;

                    } else if ((xorMask[pixel] & PIXEL_MASK) ==
                               PIXEL_MASK) {
                        //Inverted pixel, not supported in browsers.
                        //Fully opaque instead.
                        rgba[(pixel * bytesPerPixel)     ] = 0x00;
                        rgba[(pixel * bytesPerPixel) + 1 ] = 0x00;
                        rgba[(pixel * bytesPerPixel) + 2 ] = 0x00;
                        rgba[(pixel * bytesPerPixel) + 3 ] = 0xff;

                    } else {
                        //Unhandled xorMask
                        rgba[(pixel * bytesPerPixel)     ] = 0x00;
                        rgba[(pixel * bytesPerPixel) + 1 ] = 0x00;
                        rgba[(pixel * bytesPerPixel) + 2 ] = 0x00;
                        rgba[(pixel * bytesPerPixel) + 3 ] = 0xff;
                    }

                } else {
                    //Unhandled andMask
                    rgba[(pixel * bytesPerPixel)     ] = 0x00;
                    rgba[(pixel * bytesPerPixel) + 1 ] = 0x00;
                    rgba[(pixel * bytesPerPixel) + 2 ] = 0x00;
                    rgba[(pixel * bytesPerPixel) + 3 ] = 0xff;
                }
            }

        //Alpha cursor.
        } else if (cursorType == 1) {
            if (this._sock.rQwait("VMware cursor alpha encoding",
                                  (w * h * 4), 2)) {
                return false;
            }

            rgba = new Array(w * h * bytesPerPixel);

            for (let pixel = 0; pixel < (w * h); pixel++) {
                let data = this._sock.rQshift32();

                rgba[(pixel * 4)     ] = data >> 24 & 0xff; //r
                rgba[(pixel * 4) + 1 ] = data >> 16 & 0xff; //g
                rgba[(pixel * 4) + 2 ] = data >> 8 & 0xff;  //b
                rgba[(pixel * 4) + 3 ] = data & 0xff;       //a
            }

        } else {
            Log.Warn("The given cursor type is not supported: "
                      + cursorType + " given.");
            return false;
        }

        this._updateCursor(rgba, hotx, hoty, w, h);

        return true;
    }

    _handleCursor() {
        const hotx = this._FBU.x;  // hotspot-x
        const hoty = this._FBU.y;  // hotspot-y
        const w = this._FBU.width;
        const h = this._FBU.height;

        const pixelslength = w * h * 4;
        const masklength = Math.ceil(w / 8) * h;

        let bytes = pixelslength + masklength;
        if (this._sock.rQwait("cursor encoding", bytes)) {
            return false;
        }

        // Decode from BGRX pixels + bit mask to RGBA
        const pixels = this._sock.rQshiftBytes(pixelslength);
        const mask = this._sock.rQshiftBytes(masklength);
        let rgba = new Uint8Array(w * h * 4);

        let pixIdx = 0;
        for (let y = 0; y < h; y++) {
            for (let x = 0; x < w; x++) {
                let maskIdx = y * Math.ceil(w / 8) + Math.floor(x / 8);
                let alpha = (mask[maskIdx] << (x % 8)) & 0x80 ? 255 : 0;
                rgba[pixIdx    ] = pixels[pixIdx + 2];
                rgba[pixIdx + 1] = pixels[pixIdx + 1];
                rgba[pixIdx + 2] = pixels[pixIdx];
                rgba[pixIdx + 3] = alpha;
                pixIdx += 4;
            }
        }

        this._updateCursor(rgba, hotx, hoty, w, h);

        return true;
    }

    _handleDesktopName() {
        if (this._sock.rQwait("DesktopName", 4)) {
            return false;
        }

        let length = this._sock.rQshift32();

        if (this._sock.rQwait("DesktopName", length, 4)) {
            return false;
        }

        let name = this._sock.rQshiftStr(length);
        name = decodeUTF8(name, true);

        this._setDesktopName(name);

        return true;
    }

    _handleLedEvent() {
        if (this._sock.rQwait("LED status", 1)) {
            return false;
        }

        let data = this._sock.rQshift8();
        // ScrollLock state can be retrieved with data & 1. This is currently not needed.
        let numLock = data & 2 ? true : false;
        let capsLock = data & 4 ? true : false;
        this._remoteCapsLock = capsLock;
        this._remoteNumLock = numLock;

        return true;
    }

    _handleExtendedDesktopSize() {
        if (this._sock.rQwait("ExtendedDesktopSize", 4)) {
            return false;
        }

        const numberOfScreens = this._sock.rQpeek8();

        let bytes = 4 + (numberOfScreens * 16);
        if (this._sock.rQwait("ExtendedDesktopSize", bytes)) {
            return false;
        }

        const firstUpdate = !this._supportsSetDesktopSize;
        this._supportsSetDesktopSize = true;

        this._sock.rQskipBytes(1);  // number-of-screens
        this._sock.rQskipBytes(3);  // padding

        for (let i = 0; i < numberOfScreens; i += 1) {
            // Save the id and flags of the first screen
            if (i === 0) {
                this._screenID = this._sock.rQshift32();    // id
                this._sock.rQskipBytes(2);                  // x-position
                this._sock.rQskipBytes(2);                  // y-position
                this._sock.rQskipBytes(2);                  // width
                this._sock.rQskipBytes(2);                  // height
                this._screenFlags = this._sock.rQshift32(); // flags
            } else {
                this._sock.rQskipBytes(16);
            }
        }

        /*
         * The x-position indicates the reason for the change:
         *
         *  0 - server resized on its own
         *  1 - this client requested the resize
         *  2 - another client requested the resize
         */

        if (this._FBU.x === 1) {
            this._pendingRemoteResize = false;
        }

        // We need to handle errors when we requested the resize.
        if (this._FBU.x === 1 && this._FBU.y !== 0) {
            let msg = "";
            // The y-position indicates the status code from the server
            switch (this._FBU.y) {
                case 1:
                    msg = "Resize is administratively prohibited";
                    break;
                case 2:
                    msg = "Out of resources";
                    break;
                case 3:
                    msg = "Invalid screen layout";
                    break;
                default:
                    msg = "Unknown reason";
                    break;
            }
            Log.Warn("Server did not accept the resize request: "
                     + msg);
        } else {
            this._resize(this._FBU.width, this._FBU.height);
        }

        // Normally we only apply the current resize mode after a
        // window resize event. However there is no such trigger on the
        // initial connect. And we don't know if the server supports
        // resizing until we've gotten here.
        if (firstUpdate) {
            this._requestRemoteResize();
        }

        if (this._FBU.x === 1 && this._FBU.y === 0) {
            // We might have resized again whilst waiting for the
            // previous request, so check if we are in sync
            this._requestRemoteResize();
        }

        return true;
    }

    _handleDataRect() {
        let decoder = this._decoders[this._FBU.encoding];
        if (!decoder) {
            this._fail("Unsupported encoding (encoding: " +
                       this._FBU.encoding + ")");
            return false;
        }

        try {
            return decoder.decodeRect(this._FBU.x, this._FBU.y,
                                      this._FBU.width, this._FBU.height,
                                      this._sock, this._display,
                                      this._fbDepth, this._BGRmode);
        } catch (err) {
            this._fail("Error decoding rect: " + err);
            return false;
        }
    }

    _updateContinuousUpdates() {
        if (!this._enabledContinuousUpdates) { return; }

        RFB.messages.enableContinuousUpdates(this._sock, true, 0, 0,
                                             this._fbWidth, this._fbHeight);
    }

    // Handle resize-messages from the server
    _resize(width, height) {
        this._fbWidth = width;
        this._fbHeight = height;

        this._display.resize(this._fbWidth, this._fbHeight);

        // Adjust the visible viewport based on the new dimensions
        this._updateClip();
        this._updateScale();

        this._updateContinuousUpdates();

        // Keep this size until browser client size changes
        this._saveExpectedClientSize();
    }

    _xvpOp(ver, op) {
        if (this._rfbXvpVer < ver) { return; }
        Log.Info("Sending XVP operation " + op + " (version " + ver + ")");
        RFB.messages.xvpOp(this._sock, ver, op);
    }

    _updateCursor(rgba, hotx, hoty, w, h) {
        this._cursorImage = {
            rgbaPixels: rgba,
            hotx: hotx, hoty: hoty, w: w, h: h,
        };
        this._refreshCursor();
    }

    _shouldShowDotCursor() {
        // Called when this._cursorImage is updated
        if (!this._showDotCursor) {
            // User does not want to see the dot, so...
            return false;
        }

        // The dot should not be shown if the cursor is already visible,
        // i.e. contains at least one not-fully-transparent pixel.
        // So iterate through all alpha bytes in rgba and stop at the
        // first non-zero.
        for (let i = 3; i < this._cursorImage.rgbaPixels.length; i += 4) {
            if (this._cursorImage.rgbaPixels[i]) {
                return false;
            }
        }

        // At this point, we know that the cursor is fully transparent, and
        // the user wants to see the dot instead of this.
        return true;
    }

    _refreshCursor() {
        if (this._rfbConnectionState !== "connecting" &&
            this._rfbConnectionState !== "connected") {
            return;
        }
        const image = this._shouldShowDotCursor() ? RFB.cursors.dot : this._cursorImage;
        this._cursor.change(image.rgbaPixels,
                            image.hotx, image.hoty,
                            image.w, image.h
        );
    }

    static genDES(password, challenge) {
        const passwordChars = password.split('').map(c => c.charCodeAt(0));
        const key = legacyCrypto.importKey(
            "raw", passwordChars, { name: "DES-ECB" }, false, ["encrypt"]);
        return legacyCrypto.encrypt({ name: "DES-ECB" }, key, challenge);
    }
}

// Class Methods
RFB.messages = {
    keyEvent(sock, keysym, down) {
        sock.sQpush8(4); // msg-type
        sock.sQpush8(down);

        sock.sQpush16(0);

        sock.sQpush32(keysym);

        sock.flush();
    },

    QEMUExtendedKeyEvent(sock, keysym, down, keycode) {
        function getRFBkeycode(xtScanCode) {
            const upperByte = (keycode >> 8);
            const lowerByte = (keycode & 0x00ff);
            if (upperByte === 0xe0 && lowerByte < 0x7f) {
                return lowerByte | 0x80;
            }
            return xtScanCode;
        }

        sock.sQpush8(255); // msg-type
        sock.sQpush8(0); // sub msg-type

        sock.sQpush16(down);

        sock.sQpush32(keysym);

        const RFBkeycode = getRFBkeycode(keycode);

        sock.sQpush32(RFBkeycode);

        sock.flush();
    },

    pointerEvent(sock, x, y, mask) {
        sock.sQpush8(5); // msg-type

        // Marker bit must be set to 0, otherwise the server might
        // confuse the marker bit with the highest bit in a normal
        // PointerEvent message.
        mask = mask & 0x7f;
        sock.sQpush8(mask);

        sock.sQpush16(x);
        sock.sQpush16(y);

        sock.flush();
    },

    extendedPointerEvent(sock, x, y, mask) {
        sock.sQpush8(5); // msg-type

        let higherBits = (mask >> 7) & 0xff;

        // Bits 2-7 are reserved
        if (higherBits & 0xfc) {
            throw new Error("Invalid mouse button mask: " + mask);
        }

        let lowerBits = mask & 0x7f;
        lowerBits |= 0x80; // Set marker bit to 1

        sock.sQpush8(lowerBits);
        sock.sQpush16(x);
        sock.sQpush16(y);
        sock.sQpush8(higherBits);

        sock.flush();
    },

    // Used to build Notify and Request data.
    _buildExtendedClipboardFlags(actions, formats) {
        let data = new Uint8Array(4);
        let formatFlag = 0x00000000;
        let actionFlag = 0x00000000;

        for (let i = 0; i < actions.length; i++) {
            actionFlag |= actions[i];
        }

        for (let i = 0; i < formats.length; i++) {
            formatFlag |= formats[i];
        }

        data[0] = actionFlag >> 24; // Actions
        data[1] = 0x00;             // Reserved
        data[2] = 0x00;             // Reserved
        data[3] = formatFlag;       // Formats

        return data;
    },

    extendedClipboardProvide(sock, formats, inData) {
        // Deflate incomming data and their sizes
        let deflator = new Deflator();
        let dataToDeflate = [];

        for (let i = 0; i < formats.length; i++) {
            // We only support the format Text at this time
            if (formats[i] != extendedClipboardFormatText) {
                throw new Error("Unsupported extended clipboard format for Provide message.");
            }

            // Change lone \r or \n into \r\n as defined in rfbproto
            inData[i] = inData[i].replace(/\r\n|\r|\n/gm, "\r\n");

            // Check if it already has \0
            let text = encodeUTF8(inData[i] + "\0");

            dataToDeflate.push( (text.length >> 24) & 0xFF,
                                (text.length >> 16) & 0xFF,
                                (text.length >>  8) & 0xFF,
                                (text.length & 0xFF));

            for (let j = 0; j < text.length; j++) {
                dataToDeflate.push(text.charCodeAt(j));
            }
        }

        let deflatedData = deflator.deflate(new Uint8Array(dataToDeflate));

        // Build data  to send
        let data = new Uint8Array(4 + deflatedData.length);
        data.set(RFB.messages._buildExtendedClipboardFlags([extendedClipboardActionProvide],
                                                           formats));
        data.set(deflatedData, 4);

        RFB.messages.clientCutText(sock, data, true);
    },

    extendedClipboardNotify(sock, formats) {
        let flags = RFB.messages._buildExtendedClipboardFlags([extendedClipboardActionNotify],
                                                              formats);
        RFB.messages.clientCutText(sock, flags, true);
    },

    extendedClipboardRequest(sock, formats) {
        let flags = RFB.messages._buildExtendedClipboardFlags([extendedClipboardActionRequest],
                                                              formats);
        RFB.messages.clientCutText(sock, flags, true);
    },

    extendedClipboardCaps(sock, actions, formats) {
        let formatKeys = Object.keys(formats);
        let data  = new Uint8Array(4 + (4 * formatKeys.length));

        formatKeys.map(x => parseInt(x));
        formatKeys.sort((a, b) =>  a - b);

        data.set(RFB.messages._buildExtendedClipboardFlags(actions, []));

        let loopOffset = 4;
        for (let i = 0; i < formatKeys.length; i++) {
            data[loopOffset]     = formats[formatKeys[i]] >> 24;
            data[loopOffset + 1] = formats[formatKeys[i]] >> 16;
            data[loopOffset + 2] = formats[formatKeys[i]] >> 8;
            data[loopOffset + 3] = formats[formatKeys[i]] >> 0;

            loopOffset += 4;
            data[3] |= (1 << formatKeys[i]); // Update our format flags
        }

        RFB.messages.clientCutText(sock, data, true);
    },

    clientCutText(sock, data, extended = false) {
        sock.sQpush8(6); // msg-type

        sock.sQpush8(0); // padding
        sock.sQpush8(0); // padding
        sock.sQpush8(0); // padding

        let length;
        if (extended) {
            length = toUnsigned32bit(-data.length);
        } else {
            length = data.length;
        }

        sock.sQpush32(length);
        sock.sQpushBytes(data);
        sock.flush();
    },

    setDesktopSize(sock, width, height, id, flags) {
        sock.sQpush8(251); // msg-type

        sock.sQpush8(0); // padding

        sock.sQpush16(width);
        sock.sQpush16(height);

        sock.sQpush8(1); // number-of-screens

        sock.sQpush8(0); // padding

        // screen array
        sock.sQpush32(id);
        sock.sQpush16(0); // x-position
        sock.sQpush16(0); // y-position
        sock.sQpush16(width);
        sock.sQpush16(height);
        sock.sQpush32(flags);

        sock.flush();
    },

    clientFence(sock, flags, payload) {
        sock.sQpush8(248); // msg-type

        sock.sQpush8(0); // padding
        sock.sQpush8(0); // padding
        sock.sQpush8(0); // padding

        sock.sQpush32(flags);

        sock.sQpush8(payload.length);
        sock.sQpushString(payload);

        sock.flush();
    },

    enableContinuousUpdates(sock, enable, x, y, width, height) {
        sock.sQpush8(150); // msg-type

        sock.sQpush8(enable);

        sock.sQpush16(x);
        sock.sQpush16(y);
        sock.sQpush16(width);
        sock.sQpush16(height);

        sock.flush();
    },

    pixelFormat(sock, depth, trueColor, bgrMode) {
        let bpp;

        if (depth > 16) {
            bpp = 32;
        } else if (depth > 8) {
            bpp = 16;
        } else {
            bpp = 8;
        }

        const bits = Math.floor(depth/3);

        sock.sQpush8(0); // msg-type

        sock.sQpush8(0); // padding
        sock.sQpush8(0); // padding
        sock.sQpush8(0); // padding

        sock.sQpush8(bpp);
        sock.sQpush8(depth);
        sock.sQpush8(0); // little-endian
        sock.sQpush8(trueColor ? 1 : 0);

        sock.sQpush16((1 << bits) - 1); // red-max
        sock.sQpush16((1 << bits) - 1); // green-max
        sock.sQpush16((1 << bits) - 1); // blue-max

        if (bgrMode) {
            sock.sQpush8(bits * 2); // red-shift
            sock.sQpush8(bits * 1); // green-shift
            sock.sQpush8(bits * 0); // blue-shift
        } else {
            sock.sQpush8(bits * 0); // red-shift
            sock.sQpush8(bits * 1); // green-shift
            sock.sQpush8(bits * 2); // blue-shift
        }

        sock.sQpush8(0); // padding
        sock.sQpush8(0); // padding
        sock.sQpush8(0); // padding

        sock.flush();
    },

    clientEncodings(sock, encodings) {
        sock.sQpush8(2); // msg-type

        sock.sQpush8(0); // padding

        sock.sQpush16(encodings.length);
        for (let i = 0; i < encodings.length; i++) {
            sock.sQpush32(encodings[i]);
        }

        sock.flush();
    },

    fbUpdateRequest(sock, incremental, x, y, w, h) {
        if (typeof(x) === "undefined") { x = 0; }
        if (typeof(y) === "undefined") { y = 0; }

        sock.sQpush8(3); // msg-type

        sock.sQpush8(incremental ? 1 : 0);

        sock.sQpush16(x);
        sock.sQpush16(y);
        sock.sQpush16(w);
        sock.sQpush16(h);

        sock.flush();
    },

    xvpOp(sock, ver, op) {
        sock.sQpush8(250); // msg-type

        sock.sQpush8(0); // padding

        sock.sQpush8(ver);
        sock.sQpush8(op);

        sock.flush();
    }
};

RFB.cursors = {
    none: {
        rgbaPixels: new Uint8Array(),
        w: 0, h: 0,
        hotx: 0, hoty: 0,
    },

    dot: {
        /* eslint-disable indent */
        rgbaPixels: new Uint8Array([
            255, 255, 255, 255,   0,   0,   0, 255, 255, 255, 255, 255,
              0,   0,   0, 255,   0,   0,   0,   0,   0,   0,  0,  255,
            255, 255, 255, 255,   0,   0,   0, 255, 255, 255, 255, 255,
        ]),
        /* eslint-enable indent */
        w: 3, h: 3,
        hotx: 1, hoty: 1,
    }
};