security-and-privacy/CanvasBlocker
security-and-privacy/CanvasBlocker
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Code cleanup und simplification

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This commit is contained in:
kkapsner 2014-10-13 09:31:04 +02:00
parent 74e86d5d12
commit feb16823c1
1 changed files with 29 additions and 58 deletions
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87
data/inject.js
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@ -5,6 +5,7 @@
var blockMode = { var blockMode = {
getContext: { getContext: {
status: "block", status: "block",
askText: "askForPermission",
askStatus: { askStatus: {
askOnce: false, askOnce: false,
alreadyAsked: false, alreadyAsked: false,
@ -13,6 +14,7 @@
}, },
readAPI: { readAPI: {
status: "allow", status: "allow",
askText: "askForReadoutPermission",
askStatus: { askStatus: {
askOnce: false, askOnce: false,
alreadyAsked: false, alreadyAsked: false,
@ -22,42 +24,6 @@
}; };
var undef; var undef;
var originalGetContext = unsafeWindow.HTMLCanvasElement.prototype.getContext;
Object.defineProperty(
unsafeWindow.HTMLCanvasElement.prototype,
"getContext",
{
enumerable: true,
configureable: false,
get: exportFunction(function(){
switch (blockMode.getContext.status){
case "allow":
// console.log("allow");
return originalGetContext;
case "ask":
// console.log("ask");
var status = blockMode.getContext.askStatus;
var allow;
if (status.askOnce && status.alreadyAsked){
// console.log("already asked");
allow = status.answer;
}
else {
// console.log("asking");
allow = window.confirm(_("askForPermission"));
status.alreadyAsked = true;
status.answer = allow;
}
return allow? originalGetContext: undef;
case "block":
default:
// console.log("block");
return undef;
}
}, unsafeWindow)
}
);
var randomImage = (function(){ var randomImage = (function(){
var length = Math.floor(20 + Math.random() * 100); var length = Math.floor(20 + Math.random() * 100);
var bytes = ""; var bytes = "";
@ -67,18 +33,24 @@
return bytes; return bytes;
}()); }());
// Readout API blocking // changed functions
var fakeFunctions = { var changedFunctions = {
getContext: {
mode: blockMode.getContext,
object: unsafeWindow.HTMLCanvasElement
},
toDataURL: { toDataURL: {
mode: blockMode.readAPI,
object: unsafeWindow.HTMLCanvasElement, object: unsafeWindow.HTMLCanvasElement,
func: function(){ fake: function(){
var type = arguments[0] || "image/png"; var type = arguments[0] || "image/png";
return "data:" + type + ";base64," + btoa(randomImage); return "data:" + type + ";base64," + btoa(randomImage);
} }
}, },
toBlob: { toBlob: {
mode: blockMode.readAPI,
object: unsafeWindow.HTMLCanvasElement, object: unsafeWindow.HTMLCanvasElement,
func: function(callback){ fake: function(callback){
var type = arguments[0] || "image/png"; var type = arguments[0] || "image/png";
var blob = new window.Blob(randomImage, {type: type}); var blob = new window.Blob(randomImage, {type: type});
callback(blob); callback(blob);
@ -86,12 +58,13 @@
exportOptions: {allowCallbacks: true} exportOptions: {allowCallbacks: true}
}, },
mozGetAsFile: { mozGetAsFile: {
object: unsafeWindow.HTMLCanvasElement, mode: blockMode.readAPI,
func: undef object: unsafeWindow.HTMLCanvasElement
}, },
getImageData: { getImageData: {
mode: blockMode.readAPI,
object: unsafeWindow.CanvasRenderingContext2D, object: unsafeWindow.CanvasRenderingContext2D,
func: function(sx, sy, sw, sh){ fake: function(sx, sy, sw, sh){
var imageData = new window.ImageData(sw, sh); var imageData = new window.ImageData(sw, sh);
var l = sw * sh * 4; var l = sw * sh * 4;
for (var i = 0; i < l; i += 1){ for (var i = 0; i < l; i += 1){
@ -104,40 +77,38 @@
} }
}; };
Object.keys(fakeFunctions).forEach(function(name){ Object.keys(changedFunctions).forEach(function(name){
var fakeFunction = fakeFunctions[name]; var changedFunction = changedFunctions[name];
var original = fakeFunction.object.prototype[name]; var original = changedFunction.object.prototype[name];
Object.defineProperty( Object.defineProperty(
fakeFunction.object.prototype, changedFunction.object.prototype,
name, name,
{ {
enumerable: true, enumerable: true,
configureable: false, configureable: false,
get: exportFunction(function(){ get: exportFunction(function(){
var status = blockMode.readAPI.status; var status = changedFunction.mode.status;
if (status === "ask"){ if (status === "ask"){
var askStatus = blockMode.readAPI.askStatus; var askStatus = changedFunction.mode.askStatus;
var allow;
if (askStatus.askOnce && askStatus.alreadyAsked){ if (askStatus.askOnce && askStatus.alreadyAsked){
// console.log("already asked"); // console.log("already asked");
allow = askStatus.answer; status = askStatus.answer;
} }
else { else {
// console.log("asking"); // console.log("asking");
allow = window.confirm(_("askForReadoutPermission")); status = window.confirm(_(changedFunction.mode.askText))? "allow": "block";
askStatus.alreadyAsked = true; askStatus.alreadyAsked = true;
askStatus.answer = allow; askStatus.answer = status;
} }
status = allow? "allow": "block";
} }
switch (status){ switch (status){
case "allow": case "allow":
return original; return original;
case "fake": case "fake":
return fakeFunction.func? exportFunction( return changedFunction.fake? exportFunction(
fakeFunction.func, changedFunction.fake,
unsafeWindow, unsafeWindow,
fakeFunction.exportOptions changedFunction.exportOptions
): undef; ): undef;
case "block": case "block":
default: default:
@ -202,7 +173,7 @@
blockMode.getContext.status = "allow"; blockMode.getContext.status = "allow";
blockMode.readAPI.status = "allow"; blockMode.readAPI.status = "allow";
}); });
self.port.on("detach", function(force){ self.port.on("detach", function(){
blockMode.getContext.status = "allow"; blockMode.getContext.status = "allow";
blockMode.readAPI.status = "allow"; blockMode.readAPI.status = "allow";
}); });