# File actionpack/lib/action_controller/request_forgery_protection.rb, line 6
    def self.included(base)
      base.class_eval do
        class_inheritable_accessor :request_forgery_protection_options
        self.request_forgery_protection_options = {}
        helper_method :form_authenticity_token
        helper_method :protect_against_forgery?
      end
      base.extend(ClassMethods)
    end

# File actionpack/lib/action_controller/request_forgery_protection.rb, line 117
      def authenticity_token_from_cookie_session
        session[:csrf_id] ||= CGI::Session.generate_unique_id
        session.dbman.generate_digest(session[:csrf_id])
      end

# File actionpack/lib/action_controller/request_forgery_protection.rb, line 106
      def authenticity_token_from_session_id
        key = if request_forgery_protection_options[:secret].respond_to?(:call)
          request_forgery_protection_options[:secret].call(@session)
        else
          request_forgery_protection_options[:secret]
        end
        digest = request_forgery_protection_options[:digest] ||= 'SHA1'
        OpenSSL::HMAC.hexdigest(OpenSSL::Digest::Digest.new(digest), key.to_s, session.session_id.to_s)
      end

# File actionpack/lib/action_controller/request_forgery_protection.rb, line 93
      def form_authenticity_token
        @form_authenticity_token ||= if request_forgery_protection_options[:secret]
          authenticity_token_from_session_id
        elsif session.respond_to?(:dbman) && session.dbman.respond_to?(:generate_digest)
          authenticity_token_from_cookie_session
        elsif session.nil?
          raise InvalidAuthenticityToken, "Request Forgery Protection requires a valid session.  Use #allow_forgery_protection to disable it, or use a valid session."
        else
          raise InvalidAuthenticityToken, "No :secret given to the #protect_from_forgery call.  Set that or use a session store capable of generating its own keys (Cookie Session Store)."
        end
      end

# File actionpack/lib/action_controller/request_forgery_protection.rb, line 122
      def protect_against_forgery?
        allow_forgery_protection && request_forgery_protection_token
      end

# File actionpack/lib/action_controller/request_forgery_protection.rb, line 88
      def verifiable_request_format?
        request.format.html? || request.format.js?
      end

# File actionpack/lib/action_controller/request_forgery_protection.rb, line 81
      def verified_request?
        !protect_against_forgery?     ||
          request.method == :get      ||
          !verifiable_request_format? ||
          form_authenticity_token == params[request_forgery_protection_token]
      end

# File actionpack/lib/action_controller/request_forgery_protection.rb, line 72
      def verify_authenticity_token
        verified_request? || raise(ActionController::InvalidAuthenticityToken)
      end