Remove DOM dimension noise and fix document.fonts to prevent site crashes

DOM element dimension noise (offsetWidth/Height etc.) broke complex web apps
like Discord by returning fractional values where integers are expected.
Removed entirely — measureText noise is sufficient for font enumeration.

Changed document.fonts.check() to return true (uniform response) instead of
false, which caused font loading logic to hang in apps waiting for fonts.

README.md

@@ -27,8 +27,8 @@ Every website you visit is automatically placed in its own isolated container wi
 | Screen | Resolution, color depth, window dimensions |
 | Timezone | getTimezoneOffset, Date.toString, Intl.DateTimeFormat |
 | WebRTC | Forced relay-only ICE policy (blocks local IP leak) |
-| Fonts | Noise on measureText + DOM element dimensions (offsetWidth/Height etc.) |
-| Font API | document.fonts.check() blocked, size reports 0 |
+| Fonts | Noise on measureText (prevents font enumeration) |
+| Font API | document.fonts.check() returns uniform response |
 | ClientRects | Sub-pixel noise on getBoundingClientRect |
 | Plugins | Reports empty |
 | Battery | Always reports full/charging |

inject.js

@@ -470,39 +470,13 @@
       return metrics;
     }, pageWindow.CanvasRenderingContext2D.prototype, { defineAs: "measureText" });
 
-    // --- DOM Element Dimension Noise ---
-    // Font enumeration measures offsetWidth/Height of test spans to detect installed fonts.
-    // Adding seeded noise prevents consistent dimension-based font fingerprinting.
-    const fontDimProps = ["offsetWidth", "offsetHeight", "scrollWidth", "scrollHeight", "clientWidth", "clientHeight"];
-    for (const prop of fontDimProps) {
-      const origDesc = Object.getOwnPropertyDescriptor(window.HTMLElement.prototype, prop);
-      if (origDesc && origDesc.get) {
-        const origGet = origDesc.get;
-        Object.defineProperty(pageWindow.HTMLElement.prototype, prop, {
-          get: exportFunction(function() {
-            const val = origGet.call(this);
-            return val + (fontRng() - 0.5) * 0.3;
-          }, pageWindow),
-          configurable: true,
-          enumerable: true
-        });
-      }
-    }
-
     // --- document.fonts (FontFaceSet) API Protection ---
-    // document.fonts.check() directly reveals installed fonts; size/iterators expose count.
+    // document.fonts.check() always returns true so font loading logic works,
+    // but prevents enumeration of specific fonts by giving a uniform response.
     if (pageWindow.document.fonts) {
       try {
         Object.defineProperty(pageWindow.document.fonts, "check", {
-          value: exportFunction(function() { return false; }, pageWindow),
-          configurable: true, enumerable: true
-        });
-        Object.defineProperty(pageWindow.document.fonts, "size", {
-          get: exportFunction(function() { return 0; }, pageWindow),
-          configurable: true, enumerable: true
-        });
-        Object.defineProperty(pageWindow.document.fonts, "forEach", {
-          value: exportFunction(function() {}, pageWindow),
+          value: exportFunction(function() { return true; }, pageWindow),
           configurable: true, enumerable: true
         });
       } catch(e) {}

test/fingerprint-test.html

@@ -924,12 +924,13 @@ function testDocFonts() {
   report.docfonts = vals;
 
   let html = "";
-  html += row("document.fonts.size", size, size === 0 ? "spoofed" : "real");
-  html += row("check('16px Arial')", checkArial, !checkArial ? "spoofed" : "real");
-  html += row("check('16px monospace')", checkMono, !checkMono ? "spoofed" : "real");
+  html += row("document.fonts.size", size);
+  html += row("check('16px Arial')", checkArial, checkArial ? "spoofed" : "real");
+  html += row("check('16px monospace')", checkMono, checkMono ? "spoofed" : "real");
   el.innerHTML = html;
 
-  const spoofed = size === 0 && !checkArial && !checkMono;
+  // check() returning true for everything = spoofed (uniform response)
+  const spoofed = checkArial && checkMono;
   sectionStatus.docfonts = spoofed ? "pass" : "warn";
   setDot("dot-docfonts", sectionStatus.docfonts);
 }