ruby-on-railsrubyruby-on-rails-4authenticity-token

Rails 4 Authenticity Token

I was working on a new Rails 4 app (on Ruby 2.0.0-p0) when I ran into some authenticity token problems.

While writing a controller that responds to json (using the respond_to class method), I got to the create action I started getting ActionController::InvalidAuthenticityToken exceptions when I tried to create a record using curl.

I made sure I set -H "Content-Type: application/json" and I set the data with -d "<my data here>" but still no luck.

I tried writing the same controller using Rails 3.2 (on Ruby 1.9.3) and I got no authenticity token problems whatsoever. I searched around and I saw that there were some changes with authenticity tokens in Rails 4. From what I understand, they are no longer automatically inserted in forms anymore? I suppose this is somehow affecting non-HTML content types.

Is there any way to get around this without having to request a HTML form, snatching the authenticity token, then making another request with that token? Or am I completely missing something that's completely obvious?

Edit: I just tried creating a new record in a new Rails 4 app using a scaffold without changing anything and I'm running into the same problem so I guess it's not something I did.

Solution

  • I think I just figured it out. I changed the (new) default

    protect_from_forgery with: :exception

    to

    protect_from_forgery with: :null_session

    as per the comment in ApplicationController.

    # Prevent CSRF attacks by raising an exception.
# For APIs, you may want to use :null_session instead.

    You can see the difference by looking at the source for request_forgery_protecton.rb, or, more specifically, the following lines:

    In Rails 3.2:

    # This is the method that defines the application behavior when a request is found to be unverified.
# By default, \Rails resets the session when it finds an unverified request.
def handle_unverified_request
  reset_session
end

    In Rails 4:

    def handle_unverified_request
  forgery_protection_strategy.new(self).handle_unverified_request
end

    Which will call the following:

    def handle_unverified_request
  raise ActionController::InvalidAuthenticityToken
end