Added askOnlyOnce and blockReadout and major code changes

data/inject.js

@@ -1,8 +1,78 @@
+/* global self, window, console, unsafeWindow */
 (function(){
 	"use strict";
 	
-	var getContext = unsafeWindow.HTMLCanvasElement.prototype.getContext;
+	var originalGetContext = unsafeWindow.HTMLCanvasElement.prototype.getContext;
+	var originalToDataURL = unsafeWindow.HTMLCanvasElement.prototype.toDataURL;
+	var originalGetImageData = unsafeWindow.CanvasRenderingContext2D.prototype.getImageData;
 	var askFunctionName = Math.random().toString(16);
+	
+	function transformFunctionToUnsafeWindow(func, name){
+		var funcString = func.toString();
+		var parameter = funcString.match(/^function\s*\(([^\)]*)\)\s*\{/)[1];
+		funcString = funcString
+			.replace(/^function\s*\(([^\)]*)\)\s*\{|\}\s*$/g, "")
+			.replace(/(^|\n|\r)\t{3}/g, "$1")
+			.replace(/askFunctionName/g, JSON.stringify(askFunctionName))
+			.replace(/askForPermission/g, _("askForPermission"))
+			.replace(/askForInvisiblePermission/g, _("askForInvisiblePermission"));
+		var unsafeFunction = new unsafeWindow.Function(parameter, funcString);
+		unsafeFunction.toString =
+		unsafeFunction.toLocaleString =
+		unsafeFunction.toSource = new unsafeWindow.Function(
+			"return \"function " + name + "() {\\n    [native code]\\n}\";"
+		);
+		return unsafeFunction;
+	}
+	function setAPIFunctions(getContext, toDataURL, getImageData){
+		delete unsafeWindow.HTMLCanvasElement.prototype[askFunctionName];
+		if (getContext){
+			if (getContext === true){
+				getContext = originalGetContext;
+			}
+			else {
+				var secretObject = new unsafeWindow.Object();
+				Object.defineProperties(
+					secretObject,
+					{
+					  getContext: {value: originalGetContext},
+					  confirm: {value: unsafeWindow.confirm}
+					}
+				);
+				Object.defineProperty(
+					unsafeWindow.HTMLCanvasElement.prototype,
+					askFunctionName,
+					{
+						value: secretObject,
+						configurable: true,
+						enumerable: false
+					}
+				);
+				getContext = transformFunctionToUnsafeWindow(getContext, "getContext");
+			}
+		}
+		unsafeWindow.HTMLCanvasElement.prototype.getContext = getContext;
+		
+		if (toDataURL){
+			if (toDataURL === true){
+				toDataURL = originalToDataURL;
+			}
+			else {
+				toDataURL = transformFunctionToUnsafeWindow(toDataURL, "toDataURL");
+			}
+		}
+		unsafeWindow.HTMLCanvasElement.prototype.toDataURL = toDataURL;
+		
+		if (getImageData){
+			if (getImageData === true){
+				getImageData = originalGetImageData;
+			}
+			else {
+				getImageData = transformFunctionToUnsafeWindow(getImageData, "getImageData");
+			}
+		}
+		unsafeWindow.CanvasRenderingContext2D.prototype.getImageData = getImageData;
+	}
 
 	function checkPDF(blocking){
 		if (document.contentType.match(/\/pdf$/i)){
@@ -14,24 +84,14 @@
 
 	function block(force){
 		if (force || !checkPDF("block")){
-			// consoe.log("block");
+			setAPIFunctions(null, null, null);
-			delete unsafeWindow.HTMLCanvasElement.prototype[askFunctionName];
-			unsafeWindow.HTMLCanvasElement.prototype.getContext = null;
 		}
 	}
 
-	function askVisible(force){
+	function askVisible(force, askOnlyOnce){
 		if (force || !checkPDF("askVisible")){
-			
+			setAPIFunctions(
-			Object.defineProperty(
+				askOnlyOnce?
-				unsafeWindow.HTMLCanvasElement.prototype,
-				askFunctionName,
-				{
-					value: getContext,
-					enumerable: false
-				}
-			);
-			unsafeWindow.HTMLCanvasElement.prototype.getContext = new unsafeWindow.Function(
 				function(){
 					if (this.parentNode){
 						var oldBorder = this.style.border;
@@ -41,11 +101,37 @@
 						// catch (e){
 							// console.log(e.stack.split(/\s*(?:-?>|@)\s*/));
 						// }
-						var allow = confirm(confirmText);
+						var allow = this[askFunctionName].confirm.call(window, confirmText);
 						this.style.border = oldBorder;
 						if (allow){
-							this.getContext = this["askFunctionName"];
+							HTMLCanvasElement.prototype.getContext = this[askFunctionName].getContext;
-							return this["askFunctionName"].apply(this, arguments);
+							delete HTMLCanvasElement.prototype[askFunctionName];
+							return this.getContext.apply(this, arguments);
+						}
+						else {
+							HTMLCanvasElement.prototype.getContext = null;
+							delete HTMLCanvasElement.prototype[askFunctionName];
+							return null;
+						}
+					}
+					else {
+						return null;
+					}
+				}:
+				function(){
+					if (this.parentNode){
+						var oldBorder = this.style.border;
+						this.style.border = "2px dashed red";
+						var confirmText = "askForPermission";
+						// try {throw new Error();}
+						// catch (e){
+							// console.log(e.stack.split(/\s*(?:-?>|@)\s*/));
+						// }
+						var allow = this[askFunctionName].confirm.call(window, confirmText);
+						this.style.border = oldBorder;
+						if (allow){
+							this.getContext = this[askFunctionName].getContext;
+							return this.getContext.apply(this, arguments);
 						}
 						else {
 							this.getContext = null;
@@ -55,25 +141,16 @@
 					else {
 						return null;
 					}
-				}.toString()
+				},
-					.replace(/^function\s*\(\)\s*\{|\}\s*$/g, "")
+				true,
-					.replace(/askFunctionName/g, askFunctionName)
+				true
-					.replace(/askForPermission/g, _("askForPermission"))
 			);
 		}
 	}
-	function askInvisible(force){
+	function askInvisible(force, askOnlyOnce){
 		if (force || !checkPDF("askInvisible")){
-			
+			setAPIFunctions(
-			Object.defineProperty(
+				askOnlyOnce?
-				unsafeWindow.HTMLCanvasElement.prototype,
-				askFunctionName,
-				{
-					value: getContext,
-					enumerable: false
-				}
-			);
-			unsafeWindow.HTMLCanvasElement.prototype.getContext = new unsafeWindow.Function(
 				function(){
 					var oldBorder = this.style.border;
 					this.style.border = "2px dashed red";
@@ -81,32 +158,63 @@
 						this.parentNode?
 						"askForPermission":
 						"askForInvisiblePermission";
-					var allow = confirm(confirmText);
+					var allow = this[askFunctionName].confirm.call(window, confirmText);
 					this.style.border = oldBorder;
 					if (allow){
-						this.getContext = this["askFunctionName"];
+						HTMLCanvasElement.prototype.getContext = this[askFunctionName].getContext;
-						return this["askFunctionName"].apply(this, arguments);
+						delete HTMLCanvasElement.prototype[askFunctionName];
+						return this.getContext.apply(this, arguments);
+					}
+					else {
+						HTMLCanvasElement.prototype.getContext = null;
+						delete HTMLCanvasElement.prototype[askFunctionName];
+						return null;
+					}
+				}:
+				function(){
+					var oldBorder = this.style.border;
+					this.style.border = "2px dashed red";
+					var confirmText =
+						this.parentNode?
+						"askForPermission":
+						"askForInvisiblePermission";
+					var allow = this[askFunctionName].confirm.call(window, confirmText);
+					this.style.border = oldBorder;
+					if (allow){
+						this.getContext = this[askFunctionName].getContext;
+						return this.getContext.apply(this, arguments);
 					}
 					else {
 						this.getContext = null;
 						return null;
 					}
-				}.toString()
+				},
-					.replace(/^function\s*\(\)\s*\{|\}\s*$/g, "")
+				true,
-					.replace(/askFunctionName/g, askFunctionName)
+				true
-					.replace(/askForPermission/g, _("askForPermission"))
+			);
-					.replace(/askForInvisiblePermission/g, _("askForInvisiblePermission"))
+		}
+	}
+	function blockReadout(force){
+		if (force || !checkPDF("blockReadout")){
+			setAPIFunctions(
+				true,
+				function(){
+					return "data:image/png;base64";
+				},
+				function(sx, sy, sw, sh){
+					var imageData = this.createImageData(sw, sh);
+					return imageData;
+				}
 			);
 		}
 	}
 	function unblock(){
-		// console.log("unblock");
+		setAPIFunctions(true, true, true);
-		unsafeWindow.HTMLCanvasElement.prototype.getContext = getContext;
 	}
 
 	var _ = function(name){
 		return _[name] || name;
-	}
+	};
 	self.port.on("setTranslation", function(name, translation){
 		_[name] = translation;
 	});
@@ -115,6 +223,7 @@
 	self.port.on("block", block);
 	self.port.on("askVisible", askVisible);
 	self.port.on("askInvisible", askInvisible);
+	self.port.on("blockReadout", blockReadout);
 	self.port.on("unblock", unblock);
 	//self.port.on("detach", unblock); // produces memory leak due to the reference to unsafeWindow
 }());

lib/main.js

@@ -85,54 +85,67 @@
 	// }
 	function checkWorker(worker){
 		var url = new URL(worker.url);
+		var mode = "block";
 		switch (prefs.blockMode){
 			case "blockEverything":
-				worker.port.emit("block");
+				mode = "block";
 				break;
 			case "allowOnlyWhiteList":
 				if (whiteList.match(url)){
-					worker.port.emit("unblock");
+					mode = "unblock";
 				}
 				else {
-					worker.port.emit("block");
+					mode = "block";
 				}
 				break;
 			case "askVisible":
 				if (whiteList.match(url)){
-					worker.port.emit("unblock");
+					mode = "unblock";
 				}
 				else if (blackList.match(url)){
-					worker.port.emit("block");
+					mode = "block";
 				}
 				else {
-					worker.port.emit("askVisible");
+					mode = "askVisible";
 				}
 				break;
 			case "askInvisible":
 				if (whiteList.match(url)){
-					worker.port.emit("unblock");
+					mode = "unblock";
 				}
 				else if (blackList.match(url)){
-					worker.port.emit("block");
+					mode = "block";
 				}
 				else {
-					worker.port.emit("askInvisible");
+					mode = "askInvisible";
+				}
+				break;
+			case "blockReadout":
+				if (whiteList.match(url)){
+					mode = "unblock";
+				}
+				else if (blackList.match(url)){
+					mode = "block";
+				}
+				else {
+					mode = "blockReadout";
 				}
 				break;
 			case "blockOnlyBlackList":
 				if (blackList.match(url)){
-					worker.port.emit("block");
+					mode = "block";
 				}
 				else {
-					worker.port.emit("unblock");
+					mode = "unblock";
 				}
 				break;
 			case "allowEverything":
-				worker.port.emit("unblock");
+				mode = "unblock";
 				break;
 			default:
-				console.log("Unknown blocking mode.");
+				console.log("Unknown blocking mode. Default to block everything.");
 		}
+		worker.port.emit(mode, false, prefs.askOnlyOnce);
 	}
 
 
@@ -151,7 +164,7 @@
 					this.emit("unblock");
 				}
 				else {
-					this.emit(blocking, true);
+					this.emit(blocking, true, prefs.askOnlyOnce);
 				}
 			});
 			worker.port.emit("setTranslation", "askForPermission", _("askForPermission"));

locale/de-DE.properties

@@ -11,9 +11,13 @@ blockMode_options.block everything= alles blockieren
 blockMode_options.allow only white list= nur Einträge der Whitelist erlauben
 blockMode_options.ask for permission for visible <canvas>= bei sichtbaren <canvas> um Erlaubnis fragen
 blockMode_options.ask for permision for invisible <canvas>= bei unsichtbaren <canvas> um Erlaubnis fragen
+blockMode_options.block readout API= Auslese-API blockieren
 blockMode_options.block only black list= nur Einträge der Blacklist blockieren
 blockMode_options.allow everything= alles erlauben
 
+askOnlyOnce_title= Nur einmal nachfragen
+askOnlyOnce_description= Wenn eine Seite öfters versucht, die <canvas>-API abzurufen, erscheint jedes mal eine Nachfrage. Mit diesem Schalter wird pro Seitenbesuch nur einmal nachgefragt. Bei manchen Seiten kann es trotzdem zu mehrmaligem Nachfragen kommen. 
+
 allowPDFCanvas_title= <canvas> in PDFs erlauben
 allowPDFCanvas_description= Die native pdf.js verwendet <canvas> um den Inhalt von PDFs anzuzeigen. Wenn dies nicht markiert ist, werden viele Nachfragedialoge erscheinen oder die PDF Ansicht nicht funktionieren.
 

locale/en-US.properties

@@ -11,9 +11,13 @@ blockMode_options.block everything= block everything
 blockMode_options.allow only white list= allow only white list
 blockMode_options.ask for permission for visible <canvas>= ask for permission for visible <canvas>
 blockMode_options.ask for permision for invisible <canvas>= ask for permision for invisible <canvas>
+blockMode_options.block readout API= block readout API
 blockMode_options.block only black list= block only black list
 blockMode_options.allow everything= allow everything
 
+askOnlyOnce_title= Ask only once
+askOnlyOnce_description= If a page tries to access the <canvas>-API several times a confirm message will appear every time. This switch tries to make only one confirmation. Never the less on some pages there will be more.
+
 allowPDFCanvas_title= Allow canvas in PDFs
 allowPDFCanvas_description= The native pdf.js uses <canvas> to display the PDF content. If this is unchecked there will lots of annoying ask dialogs or the PDF display will not work.
 

package.json

@@ -38,6 +38,10 @@
 					"value": "askInvisible",
 					"label": "ask for permision for invisible <canvas>"
 				},
+				{
+					"value": "blockReadout",
+					"label": "block readout API"
+				},
 				{
 					"value": "blockOnlyBlackList",
 					"label": "block only black list"
@@ -48,6 +52,12 @@
 				}
 			]
 		},
+		{
+			"name": "askOnlyOnce",
+			"title": "Ask only once",
+			"type": "bool",
+			"value": false
+		},
 		{
 			"name": "allowPDFCanvas",
 			"title": "Allow canvas in PDFs",
@@ -57,6 +67,6 @@
 	],
 	"author": "Korbinian Kapsner",
 	"license": "MPL 2.0",
-	"version": "0.1.3",
+	"version": "0.1.4",
 	"permissions": {"private-browsing": true}
 }