Improve xmlPrune scriptlet

Related issue:
uBlockOrigin/uAssets#34277

Author: gorhill

src/js/resources/prevent-xhr.js

@@ -25,7 +25,10 @@ import {
     matchObjectPropertiesFn,
     parsePropertiesToMatchFn,
 } from './utils.js';
-import { proxyApplyFn } from './proxy-apply.js';
+import {
+    proxyApplyFn,
+    proxyToStringFn,
+} from './proxy-apply.js';
 import { registerScriptlet } from './base.js';
 import { safeSelf } from './safe-self.js';
 
@@ -34,6 +37,62 @@ import { safeSelf } from './safe-self.js';
 
 /******************************************************************************/
 
+export function modifyXhrResponseFn(
+    propsToMatch = '',
+    modifierFn = ''
+) {
+    if ( typeof propsToMatch !== 'string' ) { return; }
+    const safe = safeSelf();
+    if ( modifyXhrResponseFn.xhrInstances === undefined ) {
+        modifyXhrResponseFn.xhrInstances = new WeakMap();
+    }
+    const propNeedles = parsePropertiesToMatchFn(propsToMatch, 'url');
+    const NativeXMLHttpRequest = self.XMLHttpRequest;
+    const TrappedXMLHttpRequest = class XMLHttpRequest extends NativeXMLHttpRequest {
+        open(method, url, ...args) {
+            const haystack = { method, url };
+            if ( propsToMatch === '' ) {
+                safe.uboLog(`modifyXhrResponseFn() / Called: ${safe.JSON_stringify(haystack, null, 2)}`);
+            } else if ( matchObjectPropertiesFn(propNeedles, haystack) ) {
+                modifyXhrResponseFn.xhrInstances.set(this, modifierFn);
+            }
+            return super.open(method, url, ...args);
+        }
+        get response() {
+            const modifierFn = modifyXhrResponseFn.xhrInstances.get(this);
+            return modifierFn
+                ? modifierFn(this, super.response)
+                : super.response;
+        }
+        get responseText() {
+            const modifierFn = modifyXhrResponseFn.xhrInstances.get(this);
+            return modifierFn
+                ? modifierFn(this, super.responseText)
+                : super.responseText;
+        }
+        get responseXML() {
+            const modifierFn = modifyXhrResponseFn.xhrInstances.get(this);
+            return modifierFn
+                ? modifierFn(this, super.responseXML)
+                : super.responseXML;
+        }
+    };
+    proxyToStringFn(TrappedXMLHttpRequest.prototype.open, NativeXMLHttpRequest.prototype.open);
+    proxyToStringFn(TrappedXMLHttpRequest, NativeXMLHttpRequest);
+    self.XMLHttpRequest = TrappedXMLHttpRequest;
+}
+registerScriptlet(modifyXhrResponseFn, {
+    name: 'modify-xhr-response.fn',
+    dependencies: [
+        matchObjectPropertiesFn,
+        parsePropertiesToMatchFn,
+        proxyToStringFn,
+        safeSelf,
+    ],
+});
+
+/******************************************************************************/
+
 function preventXhrFn(
     trusted = false,
     propsToMatch = '',

src/js/resources/proxy-apply.js

@@ -24,6 +24,32 @@ import { registerScriptlet } from './base.js';
 
 /******************************************************************************/
 
+export function proxyToStringFn(proxiedFn, nativeFn) {
+    if ( proxyToStringFn.proxies === undefined ) {
+        proxyToStringFn.proxies = new WeakMap();
+        proxyToStringFn.nativeToString = Function.prototype.toString;
+        const proxiedToString = new Proxy(Function.prototype.toString, {
+            apply(target, thisArg) {
+                let proxied = thisArg;
+                for(;;) {
+                    const fn = proxyToStringFn.proxies.get(proxied);
+                    if ( fn === undefined ) { break; }
+                    proxied = fn;
+                }
+                return proxyToStringFn.nativeToString.call(proxied);
+            }
+        });
+        proxyToStringFn.proxies.set(proxiedToString, proxyToStringFn.nativeToString);
+        Function.prototype.toString = proxiedToString;
+    }
+    proxyToStringFn.proxies.set(proxiedFn, nativeFn);
+}
+registerScriptlet(proxyToStringFn, {
+    name: 'proxy-tostring.fn',
+});
+
+/******************************************************************************/
+
 export function proxyApplyFn(
     target = '',
     handler = '',

src/js/resources/scriptlets.js

@@ -36,7 +36,6 @@ import './prevent-fetch.js';
 import './prevent-innerHTML.js';
 import './prevent-navigation.js';
 import './prevent-settimeout.js';
-import './prevent-xhr.js';
 import './replace-argument.js';
 import './spoof-css.js';
 
@@ -54,6 +53,7 @@ import { runAt, runAtHtmlElementFn } from './run-at.js';
 import { getAllCookiesFn } from './cookie.js';
 import { getAllLocalStorageFn } from './localstorage.js';
 import { matchesStackTraceFn } from './stack-trace.js';
+import { modifyXhrResponseFn } from './prevent-xhr.js';
 import { proxyApplyFn } from './proxy-apply.js';
 import { registeredScriptlets } from './base.js';
 import { safeSelf } from './safe-self.js';
@@ -984,6 +984,7 @@ builtinScriptlets.push({
     name: 'xml-prune.js',
     fn: xmlPrune,
     dependencies: [
+        'modify-xhr-response.fn',
         'safe-self.fn',
     ],
 });
@@ -1089,41 +1090,14 @@ function xmlPrune(
             });
         }
     });
-    self.XMLHttpRequest.prototype.open = new Proxy(self.XMLHttpRequest.prototype.open, {
-        apply: async (target, thisArg, args) => {
-            if ( reUrl.test(urlFromArg(args[1])) === false ) {
-                return Reflect.apply(target, thisArg, args);
-            }
-            thisArg.addEventListener('readystatechange', function() {
-                if ( thisArg.readyState !== 4 ) { return; }
-                const type = thisArg.responseType;
-                if (
-                    type === 'document' ||
-                    type === '' && thisArg.responseXML instanceof XMLDocument
-                ) {
-                    pruneFromDoc(thisArg.responseXML);
-                    const serializer = new XMLSerializer();
-                    const textout = serializer.serializeToString(thisArg.responseXML);
-                    Object.defineProperty(thisArg, 'responseText', { value: textout });
-                    if ( typeof thisArg.response === 'string' ) {
-                        Object.defineProperty(thisArg, 'response', { value: textout });
-                    }
-                    return;
-                }
-                if (
-                    type === 'text' ||
-                    type === '' && typeof thisArg.responseText === 'string'
-                ) {
-                    const textin = thisArg.responseText;
-                    const textout = pruneFromText(textin);
-                    if ( textout === textin ) { return; }
-                    Object.defineProperty(thisArg, 'response', { value: textout });
-                    Object.defineProperty(thisArg, 'responseText', { value: textout });
-                    return;
-                }
-            });
-            return Reflect.apply(target, thisArg, args);
+    modifyXhrResponseFn(urlPattern, (xhr, before) => {
+        if ( before instanceof XMLDocument ) {
+            return pruneFromDoc(before);
+        }
+        if ( typeof before === 'string' ) {
+            return pruneFromText(before);
         }
+        return before;
     });
 }