CloudFlare Workers - 检查 Cookie、添加标头、设置 Cookie

Question

我只想通过CloudFlare workers 为首次访问者动态添加http-headers。例如这些标题：

Link: </path/to/file.css>; rel=preload; as=style; nopush
Link: </path/to/script.js>; rel=preload; as=script; nopush

所以，我需要的是以下内容，通过 JavaScript，在 CloudFlare Workers 中：

1. 检查客户端是否存在特定的cookie。
2. 如果 cookie 不存在，请添加 http-headers，然后设置该特定 cookie。
3. 如果 cookie 确实存在，则什么也不做。

您可以使用代码here。

这是来自 CF 博客的一般示例（涉及 cookie 和标头）：

// A Service Worker which skips cache if the request contains
// a cookie.
addEventListener('fetch', event => {
  let request = event.request
  if (request.headers.has('Cookie')) {
    // Cookie present. Add Cache-Control: no-cache.
    let newHeaders = new Headers(request.headers)
    newHeaders.set('Cache-Control', 'no-cache')
    event.respondWith(fetch(request, {headers: newHeaders}))
  }

  // Use default behavior.
  return
})

Answer 1

我已经设法修改了工作人员并提供了一个解决方案，如果用户在网站上发表了评论，则删除 Cache-Control 标头。

addEventListener('fetch', event => {
    event.respondWith(addHeaders(event.request))
})

async function addHeaders(request) {
    // Forward request to origin, get response.
    let response = await fetch(request)

    if (response.headers.has("Content-Type") && 
        !response.headers.get("Content-Type").includes("text/html")) {
        // File is not text/html. Pass request through.
        return fetch(request)
    }

    // Copy Response object so that we can edit headers.
    response = new Response(response.body, response)

    // Check for cookie.
    let cookies = request.headers.get('Cookie') || ""
    if (cookies.includes("returning=true")) {

        if (cookies.includes("comment_") && response.headers.has("Cache-Control")) {
            // User has commented. Delete "cache-control" header.
            response.headers.delete("Cache-Control")

            // Return on to client.
            return response
        }

        // User has been here before but has not commented.
        // Just pass request through.
        return fetch(request)
    }

    // Add headers.
    response.headers.set("Link", 
        "</path/to/file.css>; rel=preload; as=style; nopush")
    response.headers.append("Link", 
        "</path/to/script.js>; rel=preload; as=script; nopush")

    // Set cookie so that we don't add the headers next time.
    response.headers.set("Set-Cookie", "returning=true")

    // Return on to client.
    return response
}

但是，如果您尝试删除最初由 Cloudflare 设置的标头（在本例中为 Cache-Control），您将遇到未知错误 1101，这将使您的网站无法访问。您也不能修改 Cloudflare 设置的标头。显然，您只能操作按原点设置的标头并最终添加新标头。

Answer 2

这是一个 Cloudflare Worker，它实现了您所描述的内容：

addEventListener('fetch', event => {
  event.respondWith(handle(event.request))
})

async function handle(request) {
  // Check for cookie.
  let cookies = request.headers.get('Cookie') || ""
  if (cookies.includes("returning=true")) {
    // User has been here before. Just pass request through.
    return fetch(request)
  }

  // Forward request to origin, get response.
  let response = await fetch(request)

  // Copy Response object so that we can edit headers.
  response = new Response(response.body, response)

  // Add headers.
  response.headers.append("Link",
      "</path/to/file.css>; rel=preload; as=style; nopush")
  response.headers.append("Link",
      "</path/to/script.js>; rel=preload; as=script; nopush")

  // Set cookie so that we don't add the headers
  // next time.
  response.headers.set("Set-Cookie", "returning=true")

  // Return on to client.
  return response
}