Hide function replacement

Fixes #206

lib/intercept.js

@@ -161,58 +161,8 @@
 	
 	let extensionID = browser.extension.getURL("");
 	scope.intercept = function intercept({subject: window}, {check, checkStack, ask, notify, prefs}){
-		var siteStatus = check({url: getURL(window)});
-		logging.verbose("status for page", window, siteStatus);
-		if (siteStatus.mode !== "allow"){
-			apiNames.forEach(function(name){
-				var changedFunction = changedFunctions[name];
-				var functionStatus = changedFunction.getStatus(undefined, siteStatus);
-				logging.verbose("status for", name, ":", functionStatus);
-				if (functionStatus.active){
-					(
-						Array.isArray(changedFunction.object)?
-							changedFunction.object:
-							[changedFunction.object]
-					).forEach(function(object){
-						var constructor = getWrapped(window)[object];
-						if (constructor){
-							var original = constructor.prototype[name];
-						
-							Object.defineProperty(
-								constructor.prototype,
-								name,
-								{
-									enumerable: true,
-									configureable: true,
-									get: exportFunction(function(){
-										var url = getURL(window);
-										if (!url){
-											return undef;
-										}
-										var error = new Error();
-										try {
-											// return original if the extension itself requested the function
-											if (error.stack.split("\n", 3)[1].split("@", 2)[1].startsWith(extensionID)){
-												return original;
-											}
-										}
-										catch (e) {
-											// stack had an unknown form
-										}
-										if (checkStack(error.stack)){
-											return original;
-										}
-										var funcStatus = changedFunction.getStatus(this, siteStatus);
-										
-										function notifyCallback(messageId){
-											notify({
-												url,
-												errorStack: error.stack,
-												messageId,
-												timestamp: new Date(),
-												functionName: name,
-												api: changedFunction.api,
-												dataURL:
+		function getDataURL(object, prefs){
+			return (
 				this &&
 				prefs("storeImageForInspection") &&
 				prefs("showNotifications")?
@@ -226,6 +176,43 @@
 							)
 					):
 					false
+			);
+		}
+		function generateChecker(name, changedFunction, siteStatus, original){
+			return function checker(callingDepth = 2){
+				var url = getURL(window);
+				if (!url){
+					return undef;
+				}
+				var error = new Error();
+				try {
+					// return original if the extension itself requested the function
+					if (
+						error.stack
+							.split("\n", callingDepth + 2)[callingDepth + 1]
+							.split("@", callingDepth + 1)[1]
+							.startsWith(extensionID)
+					){
+						return {allow: true, original, window};
+					}
+				}
+				catch (e) {
+					// stack had an unknown form
+				}
+				if (checkStack(error.stack)){
+					return {allow: true, original, window};
+				}
+				var funcStatus = changedFunction.getStatus(this, siteStatus);
+				
+				function notifyCallback(messageId){
+					notify({
+						url,
+						errorStack: error.stack,
+						messageId,
+						timestamp: new Date(),
+						functionName: name,
+						api: changedFunction.api,
+						dataURL: getDataURL(this, prefs)
 					});
 				}
 				
@@ -248,46 +235,65 @@
 					}
 					switch (funcStatus.mode){
 						case "allow":
-													return original;
+							return {allow: true, original, window};
 						case "fake":
 							setRandomSupplyByType(prefs("rng"));
-													var fake = changedFunction.fakeGenerator(
+							return {
+								allow: "fake",
 								prefs,
-														notifyCallback,
+								notify: notifyCallback,
 								window,
 								original
-													);
-													switch (fake){
-														case true:
-															return original;
-														case false:
-															return undef;
-														default:
-															return exportFunction(fake, getWrapped(window));
-													}
+							};
 						//case "block":
 						default:
-													return undef;
+							return {
+								allow: false,
+								notify: notifyCallback
+							};
 					}
 				}
 				else {
-											return original;
+					return {allow: true, original, window};
 				}
-									}, window),
-									set: exportFunction(function(value){
-										Object.defineProperty(
-											constructor.prototype,
-											name,
-											{
-												value,
-												writable: true,
-												configurable: true,
-												enumerable: true
+			};
 		}
+		
+		var siteStatus = check({url: getURL(window)});
+		logging.verbose("status for page", window, siteStatus);
+		if (siteStatus.mode !== "allow"){
+			apiNames.forEach(function(name){
+				var changedFunction = changedFunctions[name];
+				var functionStatus = changedFunction.getStatus(undefined, siteStatus);
+				logging.verbose("status for", name, ":", functionStatus);
+				if (functionStatus.active){
+					(
+						Array.isArray(changedFunction.object)?
+							changedFunction.object:
+							[changedFunction.object]
+					).forEach(function(object){
+						var constructor = getWrapped(window)[object];
+						if (constructor){
+							var original = constructor.prototype[name];
+							const checker = generateChecker(name, changedFunction, siteStatus, original);
+							var descriptor = Object.getOwnPropertyDescriptor(constructor.prototype, name);
+							if (descriptor.hasOwnProperty("value")){
+								if (changedFunction.fakeGenerator){
+									descriptor.value = exportFunction(
+										changedFunction.fakeGenerator(checker),
+										window
 									);
-									}, window)
 								}
-							);
+								else {
+									descriptor.value = null;
+								}
+							}
+							else {
+								descriptor.get = exportFunction(function(){
+									return changedFunction.fakeGenerator(checker);
+								}, window);
+							}
+							Object.defineProperty(constructor.prototype, name, descriptor);
 						}
 					});
 				}

lib/modifiedAPI.js

@@ -17,6 +17,7 @@
 	const logging = require("./logging");
 	const {copyCanvasToWebgl} = require("./webgl");
 	const getWrapped = require("sdk/getWrapped");
+	const {hasType, checkerWrapper} = require("./modifiedAPIFunctions");
 	const modifiedAudioAPI = require("./modifiedAudioAPI");
 	
 	var randomSupply = null;
@@ -151,10 +152,6 @@
 		}
 	}
 	
-	function hasType(status, type){
-		return status.type.indexOf(type) !== -1;
-	}
-	
 	scope.setRandomSupply = function(supply){
 		randomSupply = supply;
 		modifiedAudioAPI.setRandomSupply(supply);
@@ -186,10 +183,13 @@
 				}
 			},
 			object: "HTMLCanvasElement",
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function(context, contextAttributes){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						canvasContextType.set(this, context);
-					return original.apply(this, window.Array.from(arguments));
+						return original.apply(this, window.Array.from(args));
+					});
 				};
 			}
 		},
@@ -205,18 +205,21 @@
 				return status;
 			},
 			object: "HTMLCanvasElement",
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function toDataURL(){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						if (canvasSizeShouldBeFaked(this, prefs)){
 							var fakeCanvas = getFakeCanvas(window, this, prefs);
 							if (fakeCanvas !== this){
 								notify.call(this, "fakedReadout");
 							}
-						return original.apply(fakeCanvas, window.Array.from(arguments));
+							return original.apply(fakeCanvas, window.Array.from(args));
 						}
 						else {
-						return original.apply(this, window.Array.from(arguments));
+							return original.apply(this, window.Array.from(args));
 						}
+					});
 				};
 			}
 		},
@@ -232,18 +235,21 @@
 				return status;
 			},
 			object: "HTMLCanvasElement",
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function toBlob(callback){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						if (canvasSizeShouldBeFaked(this, prefs)){
 							var fakeCanvas = getFakeCanvas(window, this, prefs);
 							if (fakeCanvas !== this){
 								notify.call(this, "fakedReadout");
 							}
-						return original.apply(fakeCanvas, window.Array.from(arguments));
+							return original.apply(fakeCanvas, window.Array.from(args));
 						}
 						else {
-						return original.apply(this, window.Array.from(arguments));
+							return original.apply(this, window.Array.from(args));
 						}
+					});
 				};
 			},
 			exportOptions: {allowCallbacks: true}
@@ -260,18 +266,21 @@
 				return status;
 			},
 			object: "HTMLCanvasElement",
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function mozGetAsFile(callback){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						if (canvasSizeShouldBeFaked(this, prefs)){
 							var fakeCanvas = getFakeCanvas(window, this, prefs);
 							if (fakeCanvas !== this){
 								notify.call(this, "fakedReadout");
 							}
-						return original.apply(fakeCanvas, window.Array.from(arguments));
+							return original.apply(fakeCanvas, window.Array.from(args));
 						}
 						else {
-						return original.apply(this, window.Array.from(arguments));
+							return original.apply(this, window.Array.from(args));
 						}
+					});
 				};
 			}
 		},
@@ -283,8 +292,10 @@
 				return status;
 			},
 			object: "CanvasRenderingContext2D",
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function getImageData(sx, sy, sw, sh){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						if (!this || canvasSizeShouldBeFaked(this.canvas, prefs)){
 							var fakeCanvas;
 							var context = this;
@@ -298,11 +309,12 @@
 									"2d"
 								);
 							}
-						return original.apply(context, window.Array.from(arguments));
+							return original.apply(context, window.Array.from(args));
 						}
 						else {
-						return original.apply(this, window.Array.from(arguments));
+							return original.apply(this, window.Array.from(args));
 						}
+					});
 				};
 			}
 		},
@@ -314,10 +326,12 @@
 				return status;
 			},
 			object: "CanvasRenderingContext2D",
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function isPointInPath(x, y){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						var rng = randomSupply.getValueRng(1, window);
-					var originalValue = original.apply(this, window.Array.from(arguments));
+						var originalValue = original.apply(this, window.Array.from(args));
 						if ((typeof originalValue) === "boolean"){
 							notify.call(this, "fakedReadout");
 							var index = x + this.width * y;
@@ -326,6 +340,7 @@
 						else {
 							return originalValue;
 						}
+					});
 				};
 			}
 		},
@@ -337,10 +352,12 @@
 				return status;
 			},
 			object: "CanvasRenderingContext2D",
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function isPointInStroke(x, y){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						var rng = randomSupply.getValueRng(1, window);
-					var originalValue = original.apply(this, window.Array.from(arguments));
+						var originalValue = original.apply(this, window.Array.from(args));
 						if ((typeof originalValue) === "boolean"){
 							notify.call(this, "fakedReadout");
 							var index = x + this.width * y;
@@ -349,6 +366,7 @@
 						else {
 							return originalValue;
 						}
+					});
 				};
 			}
 		},
@@ -360,8 +378,10 @@
 				return status;
 			},
 			object: "CanvasRenderingContext2D",
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function fillText(str, x, y){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						if (!this || canvasSizeShouldBeFaked(this.canvas, prefs)){
 							notify.call(this, "fakedInput");
 							var oldImageData;
@@ -373,14 +393,15 @@
 								// nothing to do here
 							}
 							// if "this" is not a correct context the next line will throw an error
-						var ret = original.apply(this, window.Array.from(arguments));
+							var ret = original.apply(this, window.Array.from(args));
 							var newImageData = getImageData(window, this).imageData;
 							this.putImageData(randomMixImageData(window, oldImageData, newImageData), 0, 0);
 							return ret;
 						}
 						else {
-						return original.apply(this, window.Array.from(arguments));
+							return original.apply(this, window.Array.from(args));
 						}
+					});
 				};
 			}
 		},
@@ -392,8 +413,10 @@
 				return status;
 			},
 			object: "CanvasRenderingContext2D",
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function strokeText(str, x, y){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						if (!this || canvasSizeShouldBeFaked(this.canvas, prefs)){
 							notify.call(this, "fakedInput");
 							var oldImageData;
@@ -405,14 +428,15 @@
 								// nothing to do here
 							}
 							// if "this" is not a correct context the next line will throw an error
-						var ret = original.apply(this, window.Array.from(arguments));
+							var ret = original.apply(this, window.Array.from(args));
 							var newImageData = getImageData(window, this).imageData;
 							this.putImageData(randomMixImageData(window, oldImageData, newImageData), 0, 0);
 							return ret;
 						}
 						else {
-						return original.apply(this, window.Array.from(arguments));
+							return original.apply(this, window.Array.from(args));
 						}
+					});
 				};
 			}
 		},
@@ -424,8 +448,10 @@
 				return status;
 			},
 			object: ["WebGLRenderingContext", "WebGL2RenderingContext"],
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function readPixels(x, y, width, height, format, type, pixels){ // eslint-disable-line max-params
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						if (!this || canvasSizeShouldBeFaked(this.canvas, prefs)){
 							notify.call(this, "fakedReadout");
 							var fakeCanvas = getFakeCanvas(window, this.canvas, prefs);
@@ -434,11 +460,12 @@
 								fakeCanvas,
 								this instanceof window.WebGLRenderingContext? "webgl": "webgl2"
 							);
-						return original.apply(context, window.Array.from(arguments));
+							return original.apply(context, window.Array.from(args));
 						}
 						else {
-						return original.apply(this, window.Array.from(arguments));
+							return original.apply(this, window.Array.from(args));
 						}
+					});
 				};
 			}
 		}
@@ -446,7 +473,17 @@
 	Object.keys(scope.changedFunctions).forEach(function(key){
 		scope.changedFunctions[key].api = "canvas";
 	});
-	Object.keys(modifiedAudioAPI.changedFunctions).forEach(function(key){
-		scope.changedFunctions[key] = modifiedAudioAPI.changedFunctions[key];
+	
+	scope.changedGetters = {};
+	
+	function appendModified(collection){
+		Object.keys(collection.changedFunctions || {}).forEach(function(key){
+			scope.changedFunctions[key] = collection.changedFunctions[key];
 		});
+		
+		Object.keys(collection.changedGetters || {}).forEach(function(key){
+			scope.changedGetters[key] = collection.changedGetters[key];
+		});
+	}
+	appendModified(modifiedAudioAPI);
 }());

lib/modifiedAPIFunctions.js

@@ -0,0 +1,32 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+(function(){
+	"use strict";
+	
+	var scope;
+	if ((typeof exports) !== "undefined"){
+		scope = exports;
+	}
+	else {
+		window.scope.modifiedAPIFunctions = {};
+		scope = window.scope.modifiedAPIFunctions;
+	}
+	
+	
+	
+	scope.hasType = function hasType(status, type){
+		return status.type.indexOf(type) !== -1;
+	};
+	
+	scope.checkerWrapper = function checkerWrapper(checker, object, args, callback){
+		const check = checker();
+		if (check.allow){
+			if (check.allow === true){
+				return check.original.apply(object, check.window.Array.from(args));
+			}
+			return callback.call(object, args, check);
+		}
+		return undefined;
+	};
+}());

lib/modifiedAudioAPI.js

@@ -16,6 +16,7 @@
 	const logging = require("./logging");
 	const {sha256String: hashing} = require("./hash");
 	const getWrapped = require("sdk/getWrapped");
+	const {hasType, checkerWrapper} = require("./modifiedAPIFunctions");
 	
 	var randomSupply = null;
 	
@@ -143,10 +144,6 @@
 		}
 	}
 	
-	function hasType(status, type){
-		return status.type.indexOf(type) !== -1;
-	}
-	
 	scope.setRandomSupply = function(supply){
 		randomSupply = supply;
 	};
@@ -168,79 +165,100 @@
 	scope.changedFunctions = {
 		getFloatFrequencyData: {
 			object: ["AnalyserNode"],
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function getFloatFrequencyData(array){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						notifyOnce("getFloatFrequencyData", notify);
-					var ret = original.apply(this, window.Array.from(arguments));
+						var ret = original.apply(this, window.Array.from(args));
 						fakeFloat32Array(array, window, prefs);
 						return ret;
+					});
 				};
 			}
 		},
 		getByteFrequencyData: {
 			object: ["AnalyserNode"],
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function getByteFrequencyData(array){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						notifyOnce("getByteFrequencyData", notify);
-					var ret = original.apply(this, window.Array.from(arguments));
+						var ret = original.apply(this, window.Array.from(args));
 						fakeUint8Array(array, window, prefs);
 						return ret;
+					});
 				};
 			}
 		},
 		getFloatTimeDomainData: {
 			object: ["AnalyserNode"],
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function getFloatTimeDomainData(array){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						notifyOnce("getFloatTimeDomainData", notify);
-					var ret = original.apply(this, window.Array.from(arguments));
+						var ret = original.apply(this, window.Array.from(args));
 						fakeFloat32Array(array, window, prefs);
 						return ret;
+					});
 				};
 			}
 		},
 		getByteTimeDomainData: {
 			object: ["AnalyserNode"],
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function getByteTimeDomainData(array){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						notifyOnce("getByteTimeDomainData", notify);
-					var ret = original.apply(this, window.Array.from(arguments));
+						var ret = original.apply(this, window.Array.from(args));
 						fakeUint8Array(array, window, prefs);
 						return ret;
+					});
 				};
 			}
 		},
 		getChannelData: {
 			object: ["AudioBuffer"],
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function getChannelData(channel){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						notifyOnce("getChannelData", notify);
-					var ret = original.apply(this, window.Array.from(arguments));
+						var ret = original.apply(this, window.Array.from(args));
 						fakeFloat32Array(ret, window, prefs);
 						return ret;
+					});
 				};
 			}
 		},
 		copyFromChannel: {
 			object: ["AudioBuffer"],
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function copyFromChannel(destination, channelNumber, startInChannel){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						notifyOnce("copyFromChannel", notify);
-					var ret = original.apply(this, window.Array.from(arguments));
+						var ret = original.apply(this, window.Array.from(args));
 						fakeFloat32Array(destination, window, prefs);
 						return ret;
+					});
 				};
 			}
 		},
 		getFrequencyResponse: {
 			object: ["BiquadFilterNode", "IIRFilterNode"],
-			fakeGenerator: function(prefs, notify, window, original){
+			fakeGenerator: function(checker){
 				return function getFrequencyResponse(frequencyArray, magResponseOutput, phaseResponseOutput){
+					return checkerWrapper(checker, this, arguments, function(args, check){
+						var {prefs, notify, window, original} = check;
 						notifyOnce("getFrequencyResponse", notify);
-					var ret = original.apply(this, window.Array.from(arguments));
+						var ret = original.apply(this, window.Array.from(args));
 						fakeFloat32Array(magResponseOutput, window, prefs);
 						fakeFloat32Array(phaseResponseOutput, window, prefs);
 						return ret;
+					});
 				};
 			}
 		},

manifest.json

@@ -32,6 +32,7 @@
 			"lib/colorStatistics.js",
 			"lib/webgl.js",
 			"lib/hash.js",
+			"lib/modifiedAPIFunctions.js",
 			"lib/modifiedAudioAPI.js",
 			"lib/modifiedAPI.js",
 			"lib/randomSupplies.js",

releaseNotes.txt

@@ -8,7 +8,7 @@ Version 0.4.6:
 		- Settings can be hidden
 	
 	fixes:
-		-
+		- make function replacements not detectable
 
 Version 0.4.5c:
 	new features: