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worker.js
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worker.js
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const { createContext, Script } = require("vm");
const { Request, Response, Headers } = require("node-fetch");
const { URL } = require("url");
const fetch = require("node-fetch");
const atob = require("atob");
const btoa = require("btoa");
const crypto = require("crypto").webcrypto;
const { TextDecoder, TextEncoder } = require("util");
const { caches } = require("./caches");
function chomp(str) {
return str.substr(0, str.length - 1);
}
function buildRequest(url, opts) {
const { country = "DEV", ip = "127.0.0.1", ray = `${Math.floor(1000000000000000 + Math.random() * 9000000000000000)}`, ...requestOpts } = opts;
const request = new Request(url, { redirect: "manual", ...requestOpts });
const headers = request.headers;
const parsedURL = new URL(request.url);
// CF Specific Headers
headers.set("CF-Ray", ray);
headers.set("CF-Visitor", JSON.stringify({ scheme: chomp(parsedURL.protocol) }));
headers.set("CF-IPCountry", country);
headers.set("CF-Connecting-IP", ip);
headers.set("X-Real-IP", ip);
// General Proxy Headers
headers.append("X-Forwarded-For", ip);
headers.append("X-Forwarded-Proto", chomp(parsedURL.protocol));
return new Request(request, { headers });
}
class FetchEvent {
constructor(request) {
this.responsePromise = null;
this.waitEvents = [];
this.type = "fetch";
this.request = request;
this.exceptionHandler = false;
}
waitUntil(e) {
this.waitEvents.push(e);
}
respondWith(e) {
this.responsePromise = e;
}
passThroughOnException() {
this.exceptionHandler = this.__originResponse;
}
async __response() {
const [response, ...others] = await Promise.all([this.responsePromise].concat(this.waitEvents));
return response;
}
async __originResponse() {
const response = await fetch(this.request);
return response;
};
}
class Worker {
constructor(origin, workerContents, opts = {}) {
const { upstreamHost, kvStores = {}, env = {} } = opts;
this.listeners = {
fetch: e => e.respondWith(this.fetchUpstream(e.request))
};
this.upstreamHost = upstreamHost;
this.origin = origin;
this.evaluateWorkerContents(workerContents, kvStores, env);
}
evaluateWorkerContents(workerContents, kvStores, env) {
const context = {
// From fetch
Request,
Response,
Headers,
// URL Standards
URL,
URLSearchParams,
// bas64
atob,
btoa,
// Crypto
crypto,
TextDecoder,
TextEncoder,
// Debugging
console,
// Async
setTimeout,
setInterval,
clearTimeout,
clearInterval,
// Cache stubs
caches
};
const script = new Script(workerContents);
script.runInContext(
createContext(
Object.assign(context, kvStores, env, {
fetch: this.fetchUpstream.bind(this),
addEventListener: this.addEventListener.bind(this),
triggerEvent: this.triggerEvent.bind(this),
self: context
})
)
);
}
fetchUpstream(urlOrRequest, init) {
let request = urlOrRequest instanceof Request ? urlOrRequest : new Request(urlOrRequest, init);
const url = new URL(request.url);
const originalHost = url.host;
if (originalHost === this.origin) {
url.host = this.upstreamHost;
request = new Request(url, request);
request.headers.set("Host", originalHost);
}
if (init && init.cf) {
for (var key in init.cf) {
var val = init.cf[key];
key = key.split(/(?=[A-Z])/).join('-').toUpperCase();
request.headers.set(`CF-${key}`, val);
}
}
return fetch(request);
}
async executeFetchEvent(url, opts = {}) {
const fetchEvent = new FetchEvent(buildRequest(url, opts));
try {
this.triggerEvent("fetch", fetchEvent);
return await fetchEvent.__response();
} catch (ex) {
if (fetchEvent && fetchEvent.exceptionHandler && fetchEvent.exceptionHandler instanceof Function) {
return fetchEvent.exceptionHandler();
} else {
throw ex;
}
}
}
addEventListener(event, listener) {
this.listeners[event] = listener;
}
triggerEvent(event) {
return this.listeners[event].apply(this, Array.from(arguments).slice(1));
}
}
module.exports = { Worker };