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