In a chrome extension, you can set permissions in manifest.json. I assume crossrider generates this file behind the scenes. How can change the permissions generated by a crossrider extension or is it not possible yet?
My extension in particular needs access to image and video data on all pages. This gets denied with a CORS error and I believe setting the proper permissions would solve my problem.
[EDIT]
Here's the core of my code:
try {
//all nodes in the DOM go through this function
var parseNode = function(node) {
//only get img and video tags
var nodeName = node.nodeName.toUpperCase();
if (["IMG", "VIDEO"].indexOf(nodeName) == -1)
return;
//attempt to extract their pixel data
var canvas = document.createElement("canvas");
var context = canvas.getContext("2d");
try {
console.log(node.src, " ", node.clientWidth, "x", node.clientHeight);
canvas.width = node.clientWidth; //may be zero if failed CORS
canvas.height = node.clientHeight;
context.drawImage(node, 0, 0);
var dat = context.getImageData(0, 0, canvas.width, canvas.height);
console.log("Success");
canvas.remove();
return dat.pixels;
}
catch (e) {
console.log("Failed ", node, ": ", e);
canvas.remove();
}
return null;
};
//parse everything currently loaded
var everything = document.getElementsByTagName("*");
for (var i = 0; i < everything.length; i++) {
parseNode(everything[i]);
}
//use a mutation ovserver to parse everything that gets injected later
var parseMutations = function(mutations) {
mutations.forEach(function(mutation) {
if (mutation.addedNodes) {
for (var i = 0; i < mutation.addedNodes.length; i++) {
parseNode(mutation.addedNodes[i]);
}
}
});
};
var observer = new MutationObserver(parseMutations);
observer.observe(document, {
childList: true,
subtree: true
});
}
catch (e)
{
//this has to be here since all browsers are so shit at catching syntax errors in extensions
//not to mention the crossrider extension won't install properly if there's a typo or missing semicolon. so much pain
console.log(e, " ", e.stack); //stack is pretty useless with crossrider code injection
}
On many pages I just get a tonne of these:
DOMException {
code: 18
message: "Failed to execute 'getImageData' on 'CanvasRenderingContext2D': the canvas has been tainted by cross-origin data."
name: "SecurityError"
...
[EDIT]
I've removed the try/catch so the errors print properly. I'm still seeing lots of errors.
Uncaught SecurityError: Failed to execute 'getImageData' on 'CanvasRenderingContext2D': the canvas has been tainted by cross-origin data.
I'm using this page to test with: http://en.wikipedia.org/wiki/HSL_and_HSV
"Run in IFrame" is off.
try {
//all image and video nodes in the DOM go through this function
var parseNode = function(node) {
//attempt to extract their pixel data
var canvas = document.createElement("canvas");
var context = canvas.getContext("2d");
node.title = "FAILED";
console.log(node.src, " ", node.clientWidth, "x", node.clientHeight);
canvas.width = Math.max(1, node.clientWidth); //may be zero if failed CORS
canvas.height = Math.max(1, node.clientHeight);
context.drawImage(node, 0, 0);
var dat = context.getImageData(0, 0, canvas.width, canvas.height);
canvas.remove();
return dat.pixels;
node.title = "SUCCESS";
return null;
};
//parse everything currently loaded
var everything = document.getElementsByTagName("*");
for (var i = 0; i < everything.length; i++) {
var node = everything[i];
var nodeName = node.nodeName.toUpperCase();
if (["IMG", "VIDEO"].indexOf(nodeName) != -1)
(function(n) {setTimeout(function(){parseNode(n);},1000);})(node);
}
//use a mutation ovserver to parse everything that gets injected later
var parseMutations = function(mutations) {
mutations.forEach(function(mutation) {
if (mutation.addedNodes) {
for (var i = 0; i < mutation.addedNodes.length; i++) {
var node = mutation.addedNodes[i];
var nodeName = node.nodeName.toUpperCase();
if (["IMG", "VIDEO"].indexOf(nodeName) != -1)
(function(n) {setTimeout(function(){parseNode(n);},1000);})(node);
}
}
});
};
var observer = new MutationObserver(parseMutations);
observer.observe(document, {
childList: true,
subtree: true
});
}
catch (e)
{
//this has to be here since all browsers are so shit at catching syntax errors in extensions
console.log(e, " ", e.stack); //stack is pretty useless with crossrider code injection
}
