index.js

// 把 Worker 名字改成实际版本
const WORKER_HOSTNAME = "XXX.YYY.workers.dev"

let real_hostname = null
let real_path = null

async function handleRequest(req) {
  let parsedUrl = req.url
  let referer = req.headers.get("Referer")

  // 如果有来自节点的 Referer，则修改以转发
  if (referer != null) {
      parsedUrl = referer.toString()
  }

  // 截取真正的域名和路径
  let first_char_index = parsedUrl.indexOf(WORKER_HOSTNAME) + WORKER_HOSTNAME.length + 1
  let second_char_index = parsedUrl.indexOf('/', first_char_index + 1)
  
  if (second_char_index === -1) {
    let attribute_index = parsedUrl.indexOf('?', first_char_index)
    if (attribute_index === -1) { // URL 结尾没有 /，且没有 ? 开头的查询字符串
      real_hostname = parsedUrl.substring(first_char_index)
      real_path = ''
    } else {  // 包含 ? 查询字符串
      real_hostname = parsedUrl.substring(first_char_index, attribute_index)
      real_path = parsedUrl.substring(attribute_index)
    }
  } else {  // URL 结尾有 ? /
      real_hostname = parsedUrl.substring(first_char_index, second_char_index)
      real_path = parsedUrl.substring(second_char_index)
  }

  console.log(real_hostname)
  console.log(real_path)

  const res = await fetch('https://' + real_hostname + real_path)

  // 去除 nosniff
  let clean_res = new Response(res.body, res)
  clean_res.headers.delete("x-content-type-options")
  
  const Accept = req.headers.get("Accept") || ""

  // 如果请求头 Accept 包含 text/css，则不交给 HTMLRewriter
  if (Accept.toString().indexOf("text/css") != -1) {
      const contentType = clean_res.headers.get("content-type") || ""
      if (contentType.toString().includes("text/javascript")) {
          let css_res = new Response(clean_res.body, clean_res)
          css_res.headers.set("content-type", contentType.replace("text/javascript", "text/css"))
          return css_res
      }

      clean_res.headers.set("content-type", "text/css; charset=utf-8")
      return clean_res
  }

  return rewriter.transform(clean_res)
}

class AttributeRewriter {
  constructor(attributeName) {
    this.attributeName = attributeName
  }
  element(element) {
    const attribute = element.getAttribute(this.attributeName)
    if (attribute == null) {

    } else if (attribute.startsWith('https://')) {
        element.setAttribute(
            this.attributeName,
            attribute.replace(attribute, 'https://' + WORKER_HOSTNAME + '/' + attribute.substring(8))
        )
    } else if (attribute.startsWith('//')) {
        element.setAttribute(
            this.attributeName,
            attribute.replace(attribute, '//' + WORKER_HOSTNAME + '/' + attribute.substring(2))
        )
    } else if (attribute.startsWith('/')) {
      element.setAttribute(
        this.attributeName,
        attribute.replace(attribute, '/' + real_hostname + attribute)
      )
    } else if (!attribute.startsWith('/') && attribute.indexOf('/') != 0) {
      element.setAttribute(
        this.attributeName,
        attribute.replace(attribute, '/' + real_hostname + '/' + attribute)
      )
    }
  }
}

const rewriter = new HTMLRewriter()
  .on("a", new AttributeRewriter("href"))
  .on("img", new AttributeRewriter("src"))
  .on("link", new AttributeRewriter("href"))
  .on("script", new AttributeRewriter("src"))

addEventListener("fetch", event => {
  event.respondWith(handleRequest(event.request))
})