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Prevent cross-origin js requests
class ApplicationController < ActionController::Base
before_filter :ensure_xhr
def ensure_xhr
if request.get? && request.format && (request.format.js? || request.format.json?)
head :forbidden unless request.xhr?

javan commented Dec 1, 2013

Don't bork your JSON API:

class Api::BaseController < ApplicationController
  skip_before_filter :ensure_xhr

tundal45 commented Dec 2, 2013

@javan Confused why you would need to skip the before filter in API. Wouldn't request.xhr? be true?

Draiken commented Dec 2, 2013

@tundal45 Not really. I can access an API through any place, not just the browser.


javan commented Dec 2, 2013

@tundal45 request.xhr? is only true for most ajax requests. If your API is for consumption over HTTP, you'll need to skip that check.

dhh commented Dec 2, 2013

Worth noting is that this would go hand-in-hand with all GET .js requests getting the xhr header added. So this would protect on all verbs, including GET.

homakov commented Dec 2, 2013

API doesn't usually use cookies so no private info can be CSRF-ed.

homakov commented Dec 2, 2013

@javan what about actions working like this

def index
  render 'index.js.erb'

They don't have specified params[:format]. I've seen it in the wild


javan commented Dec 2, 2013

@homakov If the incoming request doesn't have .js in the path or a javascript Accept header, request.format.js? will be false. If you've made the decision to still return js in that scenario then the above solution will not protect you.

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