1 files changed, 208 insertions, 0 deletions
diff --git a/browser/components/resistfingerprinting/test/browser/browser_canvascompare_popups_data.js b/browser/components/resistfingerprinting/test/browser/browser_canvascompare_popups_data.js
new file mode 100644
index 0000000000..caca6e0ff9
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+++ b/browser/components/resistfingerprinting/test/browser/browser_canvascompare_popups_data.js
@@ -0,0 +1,208 @@
+/**
+ * This test compares canvas randomization on a parent and a data popup, and ensures that the canvas randomization key
+ * is inherited correctly.  (e.g. that the canvases have the same random value)
+ *
+ * Covers the following cases:
+ *  - RFP/FPP is disabled entirely
+ *  - RFP is enabled entirely, and only in PBM
+ *  - FPP is enabled entirely, and only in PBM
+ *  - A normal window when FPP is enabled globally and RFP is enabled in PBM, Protections Enabled and Disabled
+ *
+ */
+
+"use strict";
+
+// =============================================================================================
+
+/**
+ * Compares two Uint8Arrays and returns the number of bits that are different.
+ *
+ * @param {Uint8ClampedArray} arr1 - The first Uint8ClampedArray to compare.
+ * @param {Uint8ClampedArray} arr2 - The second Uint8ClampedArray to compare.
+ * @returns {number} - The number of bits that are different between the two
+ *                     arrays.
+ */
+function countDifferencesInUint8Arrays(arr1, arr2) {
+  let count = 0;
+  for (let i = 0; i < arr1.length; i++) {
+    let diff = arr1[i] ^ arr2[i];
+    while (diff > 0) {
+      count += diff & 1;
+      diff >>= 1;
+    }
+  }
+  return count;
+}
+
+// =============================================================================================
+
+async function testCanvasRandomization(result, expectedResults, extraData) {
+  let testDesc = extraData.testDesc;
+
+  let parent = result.mine;
+  let child = result.theirs;
+
+  let differencesInRandom = countDifferencesInUint8Arrays(parent, child);
+  let differencesFromUnmodifiedParent = countDifferencesInUint8Arrays(
+    UNMODIFIED_CANVAS_DATA,
+    parent
+  );
+  let differencesFromUnmodifiedChild = countDifferencesInUint8Arrays(
+    UNMODIFIED_CANVAS_DATA,
+    child
+  );
+
+  Assert.greaterOrEqual(
+    differencesFromUnmodifiedParent,
+    expectedResults[0],
+    `Checking ${testDesc} for canvas randomization, comparing parent - lower bound for random pixels.`
+  );
+  Assert.lessOrEqual(
+    differencesFromUnmodifiedParent,
+    expectedResults[1],
+    `Checking ${testDesc} for canvas randomization, comparing parent - upper bound for random pixels.`
+  );
+
+  Assert.greaterOrEqual(
+    differencesFromUnmodifiedChild,
+    expectedResults[0],
+    `Checking ${testDesc} for canvas randomization, comparing child - lower bound for random pixels.`
+  );
+  Assert.lessOrEqual(
+    differencesFromUnmodifiedChild,
+    expectedResults[1],
+    `Checking ${testDesc} for canvas randomization, comparing child - upper bound for random pixels.`
+  );
+
+  Assert.greaterOrEqual(
+    differencesInRandom,
+    expectedResults[2],
+    `Checking ${testDesc} and comparing randomization - lower bound for different random pixels.`
+  );
+  Assert.lessOrEqual(
+    differencesInRandom,
+    expectedResults[3],
+    `Checking ${testDesc} and comparing randomization - upper bound for different random pixels.`
+  );
+}
+
+requestLongerTimeout(2);
+
+let expectedResults = {};
+var UNMODIFIED_CANVAS_DATA = undefined;
+
+add_setup(async function () {
+  // Disable the fingerprinting randomization.
+  await SpecialPowers.pushPrefEnv({
+    set: [
+      ["privacy.fingerprintingProtection", false],
+      ["privacy.fingerprintingProtection.pbmode", false],
+      ["privacy.resistFingerprinting", false],
+    ],
+  });
+
+  let extractCanvasData = function () {
+    let offscreenCanvas = new OffscreenCanvas(100, 100);
+
+    const context = offscreenCanvas.getContext("2d");
+
+    // Draw a red rectangle
+    context.fillStyle = "#EE2222";
+    context.fillRect(0, 0, 100, 100);
+    context.fillStyle = "#2222EE";
+    context.fillRect(20, 20, 100, 100);
+
+    const imageData = context.getImageData(0, 0, 100, 100);
+    return imageData.data;
+  };
+
+  function runExtractCanvasData(tab) {
+    let code = extractCanvasData.toString();
+    return SpecialPowers.spawn(tab.linkedBrowser, [code], async funccode => {
+      await content.eval(`var extractCanvasData = ${funccode}`);
+      let result = await content.eval(`extractCanvasData()`);
+      return result;
+    });
+  }
+
+  const emptyPage =
+    getRootDirectory(gTestPath).replace(
+      "chrome://mochitests/content",
+      "https://example.com"
+    ) + "empty.html";
+
+  // Open a tab for extracting the canvas data.
+  const tab = await BrowserTestUtils.openNewForegroundTab(gBrowser, emptyPage);
+
+  let data = await runExtractCanvasData(tab);
+  UNMODIFIED_CANVAS_DATA = data;
+
+  BrowserTestUtils.removeTab(tab);
+  await SpecialPowers.popPrefEnv();
+});
+
+// Be sure to always use `let expectedResults = structuredClone(allNotSpoofed)` to do a
+//   deep copy and avoiding corrupting the original 'const' object
+// The first value represents the minimum number of random pixels we should see
+// The second, the maximum number of random pixels
+// The third, the minimum number of differences between the canvases of the parent and child
+// The fourth, the maximum number of differences between the canvases of the parent and child
+const rfpFullyRandomized = [10000, 999999999, 20000, 999999999];
+const fppRandomizedSameDomain = [1, 260, 0, 0];
+const noRandom = [0, 0, 0, 0];
+
+let uri = `https://${IFRAME_DOMAIN}/browser/browser/components/resistfingerprinting/test/browser/file_canvascompare_data_popupmaker.html`;
+
+expectedResults = structuredClone(noRandom);
+add_task(
+  defaultsTest.bind(null, uri, testCanvasRandomization, expectedResults)
+);
+
+expectedResults = structuredClone(fppRandomizedSameDomain);
+add_task(
+  defaultsPBMTest.bind(null, uri, testCanvasRandomization, expectedResults)
+);
+
+expectedResults = structuredClone(rfpFullyRandomized);
+add_task(
+  simpleRFPTest.bind(null, uri, testCanvasRandomization, expectedResults)
+);
+
+// Test a private window with RFP enabled in PBMode
+expectedResults = structuredClone(rfpFullyRandomized);
+add_task(
+  simplePBMRFPTest.bind(null, uri, testCanvasRandomization, expectedResults)
+);
+
+expectedResults = structuredClone(fppRandomizedSameDomain);
+add_task(
+  simpleFPPTest.bind(null, uri, testCanvasRandomization, expectedResults)
+);
+
+// Test a Private Window with FPP Enabled in PBM
+expectedResults = structuredClone(fppRandomizedSameDomain);
+add_task(
+  simplePBMFPPTest.bind(null, uri, testCanvasRandomization, expectedResults)
+);
+
+// Test RFP Enabled in PBM and FPP enabled in Normal Browsing Mode, No Protections
+expectedResults = structuredClone(noRandom);
+add_task(
+  RFPPBMFPP_NormalMode_NoProtectionsTest.bind(
+    null,
+    uri,
+    testCanvasRandomization,
+    expectedResults
+  )
+);
+
+// Test RFP Enabled in PBM and FPP enabled in Normal Browsing Mode, Protections Enabled
+expectedResults = structuredClone(fppRandomizedSameDomain);
+add_task(
+  RFPPBMFPP_NormalMode_ProtectionsTest.bind(
+    null,
+    uri,
+    testCanvasRandomization,
+    expectedResults
+  )
+);