Add Zlib encoding

Author: markpeek

README.md

@@ -66,7 +66,7 @@ profits such as:
   RSA-AES, Tight, VeNCrypt Plain, XVP, Apple's Diffie-Hellman,
   UltraVNC's MSLogonII
 * Supported VNC encodings: raw, copyrect, rre, hextile, tight, tightPNG,
-  ZRLE, JPEG
+  ZRLE, JPEG, Zlib
 * Supports scaling, clipping and resizing the desktop
 * Local cursor rendering
 * Clipboard copy/paste with full Unicode support

core/decoders/zlib.js

@@ -0,0 +1,51 @@
+/*
+ * noVNC: HTML5 VNC client
+ * Copyright (C) 2024 The noVNC Authors
+ * Licensed under MPL 2.0 (see LICENSE.txt)
+ *
+ * See README.md for usage and integration instructions.
+ *
+ */
+
+import Inflator from "../inflator.js";
+
+export default class ZlibDecoder {
+    constructor() {
+        this._zlib = new Inflator();
+        this._length = 0;
+    }
+
+    decodeRect(x, y, width, height, sock, display, depth) {
+        if ((width === 0) || (height === 0)) {
+            return true;
+        }
+
+        if (this._length === 0) {
+            if (sock.rQwait("ZLIB", 4)) {
+                return false;
+            }
+
+            this._length = sock.rQshift32();
+        }
+
+        if (sock.rQwait("ZLIB", this._length)) {
+            return false;
+        }
+
+        let data = new Uint8Array(sock.rQshiftBytes(this._length, false));
+        this._length = 0;
+
+        this._zlib.setInput(data);
+        data = this._zlib.inflate(width * height * 4);
+        this._zlib.setInput(null);
+
+        // Max sure the image is fully opaque
+        for (let i = 0; i < width * height; i++) {
+            data[i * 4 + 3] = 255;
+        }
+
+        display.blitImage(x, y, width, height, data, 0);
+
+        return true;
+    }
+}

core/encodings.js

@@ -11,6 +11,7 @@ export const encodings = {
     encodingCopyRect: 1,
     encodingRRE: 2,
     encodingHextile: 5,
+    encodingZlib: 6,
     encodingTight: 7,
     encodingZRLE: 16,
     encodingTightPNG: -260,
@@ -40,6 +41,7 @@ export function encodingName(num) {
         case encodings.encodingCopyRect: return "CopyRect";
         case encodings.encodingRRE:      return "RRE";
         case encodings.encodingHextile:  return "Hextile";
+        case encodings.encodingZlib:     return "Zlib";
         case encodings.encodingTight:    return "Tight";
         case encodings.encodingZRLE:     return "ZRLE";
         case encodings.encodingTightPNG: return "TightPNG";

core/rfb.js

@@ -31,6 +31,7 @@ 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";
@@ -244,6 +245,7 @@ export default class RFB extends EventTargetMixin {
         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();
@@ -2121,6 +2123,7 @@ export default class RFB extends EventTargetMixin {
             encs.push(encodings.encodingJPEG);
             encs.push(encodings.encodingHextile);
             encs.push(encodings.encodingRRE);
+            encs.push(encodings.encodingZlib);
         }
         encs.push(encodings.encodingRaw);
 

tests/test.zlib.js

@@ -0,0 +1,84 @@
+import Websock from '../core/websock.js';
+import Display from '../core/display.js';
+
+import ZlibDecoder from '../core/decoders/zlib.js';
+
+import FakeWebSocket from './fake.websocket.js';
+
+function testDecodeRect(decoder, x, y, width, height, data, display, depth) {
+    let sock;
+    let done = false;
+
+    sock = new Websock;
+    sock.open("ws://example.com");
+
+    sock.on('message', () => {
+        done = decoder.decodeRect(x, y, width, height, sock, display, depth);
+    });
+
+    // Empty messages are filtered at multiple layers, so we need to
+    // do a direct call
+    if (data.length === 0) {
+        done = decoder.decodeRect(x, y, width, height, sock, display, depth);
+    } else {
+        sock._websocket._receiveData(new Uint8Array(data));
+    }
+
+    display.flip();
+
+    return done;
+}
+
+describe('Zlib Decoder', function () {
+    let decoder;
+    let display;
+
+    before(FakeWebSocket.replace);
+    after(FakeWebSocket.restore);
+
+    beforeEach(function () {
+        decoder = new ZlibDecoder();
+        display = new Display(document.createElement('canvas'));
+        display.resize(4, 4);
+    });
+
+    it('should handle the Zlib encoding', function () {
+        let done;
+
+        let zlibData = new Uint8Array([
+            0x00, 0x00, 0x00, 0x23, /* length */
+            0x78, 0x01, 0xfa, 0xcf, 0x00, 0x04, 0xff, 0x61, 0x04, 0x90, 0x01, 0x41, 0x50, 0xc1, 0xff, 0x0c,
+            0xef, 0x40, 0x02, 0xef, 0xfe, 0x33, 0xac, 0x02, 0xe2, 0xd5, 0x40, 0x8c, 0xce, 0x07, 0x00, 0x00,
+            0x00, 0xff, 0xff,
+        ]);
+        done = testDecodeRect(decoder, 0, 0, 4, 4, zlibData, display, 24);
+        expect(done).to.be.true;
+
+        let targetData = new Uint8ClampedArray([
+            0xff, 0x00, 0x00, 255, 0x00, 0xff, 0x00, 255, 0x00, 0x00, 0xff, 255, 0x00, 0x00, 0xff, 255,
+            0x00, 0xff, 0x00, 255, 0xff, 0x00, 0x00, 255, 0x00, 0x00, 0xff, 255, 0x00, 0x00, 0xff, 255,
+            0xee, 0x00, 0xff, 255, 0x00, 0xee, 0xff, 255, 0xaa, 0xee, 0xff, 255, 0xab, 0xee, 0xff, 255,
+            0xee, 0x00, 0xff, 255, 0x00, 0xee, 0xff, 255, 0xaa, 0xee, 0xff, 255, 0xab, 0xee, 0xff, 255
+        ]);
+
+        expect(display).to.have.displayed(targetData);
+    });
+
+    it('should handle empty rects', function () {
+        display.fillRect(0, 0, 4, 4, [0x00, 0x00, 0xff]);
+        display.fillRect(2, 0, 2, 2, [0x00, 0xff, 0x00]);
+        display.fillRect(0, 2, 2, 2, [0x00, 0xff, 0x00]);
+
+        let done = testDecodeRect(decoder, 1, 2, 0, 0, [], display, 24);
+
+        let targetData = new Uint8Array([
+            0x00, 0x00, 0xff, 255, 0x00, 0x00, 0xff, 255, 0x00, 0xff, 0x00, 255, 0x00, 0xff, 0x00, 255,
+            0x00, 0x00, 0xff, 255, 0x00, 0x00, 0xff, 255, 0x00, 0xff, 0x00, 255, 0x00, 0xff, 0x00, 255,
+            0x00, 0xff, 0x00, 255, 0x00, 0xff, 0x00, 255, 0x00, 0x00, 0xff, 255, 0x00, 0x00, 0xff, 255,
+            0x00, 0xff, 0x00, 255, 0x00, 0xff, 0x00, 255, 0x00, 0x00, 0xff, 255, 0x00, 0x00, 0xff, 255
+        ]);
+
+        expect(done).to.be.true;
+        expect(display).to.have.displayed(targetData);
+    });
+});