add patch google analytics response modifier

proxychain/responsemodifers/patch_google_analytics.go

@@ -0,0 +1,33 @@
+package responsemodifers
+
+import (
+	_ "embed"
+	"io"
+	"ladder/proxychain"
+	"strings"
+)
+
+//go:embed patch_google_analytics.js
+var gaPatch string
+
+// PatchGoogleAnalytics replaces any request to google analytics with a no-op stub function.
+// Some sites will not display content until GA is loaded, so we fake one instead.
+// Credit to Raymond Hill @ github.com/gorhill/uBlock
+func PatchGoogleAnalytics() proxychain.ResponseModification {
+	return func(chain *proxychain.ProxyChain) error {
+
+		// preflight check
+		isGADomain := chain.Request.URL.Host == "www.google-analytics.com" || chain.Request.URL.Host == "google-analytics.com"
+		isGAPath := strings.HasSuffix(chain.Request.URL.Path, "analytics.js")
+		if !(isGADomain || isGAPath) {
+			return nil
+		}
+
+		// send modified js payload to client containing
+		// stub functions from patch_google_analytics.js
+		gaPatchReader := io.NopCloser(strings.NewReader(gaPatch))
+		chain.Response.Body = gaPatchReader
+		chain.Context.Set("content-type", "text/javascript")
+		return nil
+	}
+}

proxychain/responsemodifers/patch_google_analytics.js

@@ -0,0 +1,109 @@
+// uBlock Origin - a browser extension to block requests.
+// Copyright (C) 2019-present Raymond Hill
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see {http://www.gnu.org/licenses/}.
+//
+// Home: https://github.com/gorhill/uBlock
+
+(function() {
+  "use strict";
+  // https://developers.google.com/analytics/devguides/collection/analyticsjs/
+  const noopfn = function() {
+  };
+  //
+  const Tracker = function() {
+  };
+  const p = Tracker.prototype;
+  p.get = noopfn;
+  p.set = noopfn;
+  p.send = noopfn;
+  //
+  const w = window;
+  const gaName = w.GoogleAnalyticsObject || "ga";
+  const gaQueue = w[gaName];
+  // https://github.com/uBlockOrigin/uAssets/pull/4115
+  const ga = function() {
+    const len = arguments.length;
+    if (len === 0) return;
+    const args = Array.from(arguments);
+    let fn;
+    let a = args[len - 1];
+    if (a instanceof Object && a.hitCallback instanceof Function) {
+      fn = a.hitCallback;
+    } else if (a instanceof Function) {
+      fn = () => {
+        a(ga.create());
+      };
+    } else {
+      const pos = args.indexOf("hitCallback");
+      if (pos !== -1 && args[pos + 1] instanceof Function) {
+        fn = args[pos + 1];
+      }
+    }
+    if (fn instanceof Function === false) return;
+    try {
+      fn();
+    } catch (ex) {
+    }
+  };
+  ga.create = function() {
+    return new Tracker();
+  };
+  ga.getByName = function() {
+    return new Tracker();
+  };
+  ga.getAll = function() {
+    return [new Tracker()];
+  };
+  ga.remove = noopfn;
+  // https://github.com/uBlockOrigin/uAssets/issues/2107
+  ga.loaded = true;
+  w[gaName] = ga;
+  // https://github.com/gorhill/uBlock/issues/3075
+  const dl = w.dataLayer;
+  if (dl instanceof Object) {
+    if (dl.hide instanceof Object && typeof dl.hide.end === "function") {
+      dl.hide.end();
+      dl.hide.end = () => { };
+    }
+    if (typeof dl.push === "function") {
+      const doCallback = function(item) {
+        if (item instanceof Object === false) return;
+        if (typeof item.eventCallback !== "function") return;
+        setTimeout(item.eventCallback, 1);
+        item.eventCallback = () => { };
+      };
+      dl.push = new Proxy(dl.push, {
+        apply: function(target, thisArg, args) {
+          doCallback(args[0]);
+          return Reflect.apply(target, thisArg, args);
+        },
+      });
+      if (Array.isArray(dl)) {
+        const q = dl.slice();
+        for (const item of q) {
+          doCallback(item);
+        }
+      }
+    }
+  }
+  // empty ga queue
+  if (gaQueue instanceof Function && Array.isArray(gaQueue.q)) {
+    const q = gaQueue.q.slice();
+    gaQueue.q.length = 0;
+    for (const entry of q) {
+      ga(...entry);
+    }
+  }
+})();