support js URL rewriting; support post req

proxychain/responsemodifers/rewrite_js_resource_urls.js

@@ -0,0 +1,76 @@
+// Overrides the global fetch and XMLHttpRequest open methods to modify the request URLs.
+// Also overrides the attribute setter prototype to modify the request URLs
+// fetch("/relative_script.js") -> fetch("http://localhost:8080/relative_script.js")
+(() => {
+   function rewriteURL(url) {
+        oldUrl = url 
+        if (!url) return url
+
+        proxyOrigin = globalThis.window.location.origin
+        if (url.startsWith(proxyOrigin)) return url
+
+        const origin = (new URL(decodeURI(globalThis.window.location.pathname.substring(1)))).origin
+        if (url.startsWith("//")) {
+            url = `/${origin}/${encodeURIComponent(url.substring(2))}`;
+        } else if (url.startsWith("/")) {
+            url = `/${origin}/${encodeURIComponent(url.substring(1))}`;
+        } else if (url.startsWith("http://") || url.startsWith("https://")) {
+            url = `/${origin}/${encodeURIComponent(url)}`;
+        }
+        console.log(`rewrite JS URL: ${oldUrl} -> ${url}`)
+        return url;
+   };
+
+   // monkey patch fetch
+   const oldFetch = globalThis.fetch;
+   globalThis.fetch = async (url, init) => {
+        return oldFetch(rewriteURL(url), init)
+   }
+
+   // monkey patch xmlhttprequest
+   const oldOpen = XMLHttpRequest.prototype.open;
+   XMLHttpRequest.prototype.open = function(method, url, async = true, user = null, password = null) {
+       return oldOpen.call(this, method, rewriteURL(url), async, user, password);
+   };
+   const oldSend = XMLHttpRequest.prototype.send;
+   XMLHttpRequest.prototype.send = function(method, url) {
+       return oldSend.call(this, method, rewriteURL(url));
+   };
+
+   // monkey patch service worker registration
+   const oldRegister = ServiceWorkerContainer.prototype.register;
+   ServiceWorkerContainer.prototype.register = function(scriptURL, options) {
+        return oldRegister.call(this, rewriteURL(scriptURL), options)
+   }
+
+    // Monkey patch setter methods
+    const elements = [
+        { tag: 'a', attribute: 'href' },
+        { tag: 'img', attribute: 'src' },
+        { tag: 'script', attribute: 'src' },
+        { tag: 'link', attribute: 'href' },
+        { tag: 'iframe', attribute: 'src' },
+        { tag: 'audio', attribute: 'src' },
+        { tag: 'video', attribute: 'src' },
+        { tag: 'source', attribute: 'src' },
+        { tag: 'embed', attribute: 'src' },
+        { tag: 'object', attribute: 'src' },
+        { tag: 'input', attribute: 'src' },
+        { tag: 'track', attribute: 'src' },
+        { tag: 'form', attribute: 'action' },
+    ];
+
+    elements.forEach(({ tag, attribute }) => {
+        const proto = document.createElement(tag).constructor.prototype;
+        const descriptor = Object.getOwnPropertyDescriptor(proto, attribute);
+        if (descriptor && descriptor.set) {
+            Object.defineProperty(proto, attribute, {
+                ...descriptor,
+                set(value) {
+                    return descriptor.set.call(this, rewriteURL(value));
+                }
+            });
+        }
+    });
+
+})();