为 Rails 中的 navigator.sendBeacon 请求处理 CSRF 真实性令牌

Question

    $(window).on('unload', function() {
        db.flipCounter.get(gon.slug, function(obj) {
            var payload = {
                slug: gon.slug,
                localFlipCount: obj.fc,
                time: Date.now()
            }

            navigator.sendBeacon('/analytics', csrfProtect(payload))

        })
    })

    function csrfProtect(payload) {
        var param = $("meta[name=csrf-param]").attr("content")
        var token = $("meta[name=csrf-token]").attr("content")

        if (param && token) payload[param] = token
        return new Blob([JSON.stringify(payload)], { type: "application/x-www-form-urlencoded; charset=utf-8" })
    }

在上面的代码中，我希望使用有效负载将 POST 发送到“/analytics”网址。我在尝试触发请求时收到以下错误（警告）：

Promise.js:840 未处理的拒绝：TypeError：无法在字符串 '{"slug":"test-page-by-marvin-danig","localFlipCount":1,"time":1524241435403}' 上创建属性 'authenticity_token'

嗯。

…发出请求，我得到：

Processing by BooksController#analytics as */*
  Parameters: {"{\"slug\":\"test-book-by-marvin-danig\",\"localFlipCount\":1,\"time\":1524243279653,\"param\":\"8rzDx/TNL8YeU1/NWgWSk6gB/UvmbB9Ip VajDCgfDUv5Q4pjh7x0GUG1il1jDJajtJyHf84Xv5Pt14fiCnA9w"=>"=\"}"}
Can't verify CSRF token authenticity.
exception
ActionController::InvalidAuthenticityToken

---

更新：问题仍未解决。这是我现在所处的位置：

我的 GET 和 POST 路由打开了routes.rb：

# Analytics (flipCounter)
  get 'auth_token', to: 'analytics#auth_token'
  post 'receptor', to: 'analytics#receptor', as: :receptor  

这些显然映射到analytics_controller这样的：

class AnalyticsController < ApplicationController
    respond_to :js

  def auth_token
    session[:_csrf_token] = form_authenticity_token
  end

  def receptor
    logger.debug "Check book slug first: #{params}" 

    begin
      book = Book.friendly.find(params[:slug])
    rescue ActiveRecord::RecordNotFound => e
      book = nil
    end

    if book.exists?
      book.flipcount += params[:flipcount].to_i
    end

  end
    private

end 

除了auth_token方法之外，我还得到了一个auth_token.json.erb模板，按以下方式提供：

{ "authenticity_token": "<%= session[:_csrf_token] %>" } 

客户端 javascript（草稿不佳）采用以下方式：

            // When state of book changes to `not_flipping`:

                flipCount += 1

                const o = { slug: gon.slug, fc: flipCount }

            // IndexedDb initiated elsewhere.
            db.transaction('rw', db.flipCounter, function(e) {
                db.flipCounter.put(o)
            }).then(function(e) {
                const URL = '/auth_token' // First fetch the authenticity_token!
                fetch(URL, {
                    method: 'GET'
                }).then(function(res) {
                    return res.json()
                }).then(function(token) {


                    return postBookData(token)


                }).catch(err => console.log(err))
            }).catch(function(e) {
                console.log(e)
            })


            function postBookData(token) {

                db.flipCounter.get(gon.slug, function(obj) {
                    // var payload = new FormData()

                    // payload.append('slug', gon.slug)
                    // payload.append('localFlipCount', obj.fc)
                    // payload.append('authenticity_token', token.authenticity_token)
                    // payload.append('type', 'application/x-www-form-urlencoded;')
                    // payload.append('charset=utf-8', 'ok')
                    //  payload.append('X-CSRF-Token', token.authenticity_token)

                    //var payload = { 'slug': gon.slug }

                    let body = {
                        slug: gon.slug,
                        flipcount: obj.fc,
                        time: Date.now()
                    }
                    let headers = {
                        type: 'application/x-www-form-urlencoded; charset=utf-8',
                        'X-CSRF-Token': token.authenticity_token
                    }
                    let blob = new Blob([JSON.stringify(body)], headers);
                    let url = '/receptor'

                    navigator.sendBeacon(url, blob);

                }).then(function() {
                    flipCount = 0
                    var o = { slug: gon.slug, fc: flipCount }
                }).catch(err => console.log(err))
            }

触发的请求对象navigator.sendBeacon不正确，因为X-CSRF-Token未设置，我显然在服务器端收到以下错误：

Started POST "/receptor" for 127.0.0.1 at 2018-04-26 09:00:33 -0400
Processing by AnalyticsController#receptor as */*
  Parameters: {"{\"slug\":\"bookiza-documentation-by-marvin-danig\",\"fc\":1}"=>nil}
Can't verify CSRF token authenticity.
exception
ActionController::InvalidAuthenticityToken
  Rendering public/500.html
  Rendered public/500.html (1.0ms)
Completed 500 Internal Server Error in 337ms (Views: 335.8ms | ActiveRecord: 0.0ms)

有没有人navigator.sendBeacon使用服务工作者在完全离线的页面上在 Rails 应用程序上实现了一个场景？

Answer 1

刚抓住这个障碍，我的解决方案的js端如下：

window.addEventListener("unload", function() {
  var url = "/your_metrics_path",
  data = new FormData(),
  token = $('meta[name="csrf-token"]').attr('content');
  // add your data
  data.append("foo", "bar");
  // add the auth token
  data.append("authenticity_token", token);
  // off she goes
  navigator.sendBeacon(url, data);
});

希望这可以帮助。