Reorganize CSRF a bit

actionpack/lib/action_controller/metal/request_forgery_protection.rb

@@ -5,7 +5,6 @@ class InvalidAuthenticityToken < ActionControllerError #:nodoc:
   module RequestForgeryProtection
     extend ActiveSupport::Concern
 
-    # TODO : Remove the defined? check when new base is the main base
     include AbstractController::Helpers, Session
 
     included do
@@ -21,26 +20,26 @@ module RequestForgeryProtection
       helper_method :protect_against_forgery?
     end
     
-    # Protecting controller actions from CSRF attacks by ensuring that all forms are coming from the current web application, not a
-    # forged link from another site, is done by embedding a token based on a random string stored in the session (which an attacker wouldn't know) in all
-    # forms and Ajax requests generated by Rails and then verifying the authenticity of that token in the controller.  Only
-    # HTML/JavaScript requests are checked, so this will not protect your XML API (presumably you'll have a different authentication
-    # scheme there anyway).  Also, GET requests are not protected as these should be idempotent anyway.
+    # Protecting controller actions from CSRF attacks by ensuring that all forms are coming from the current 
+    # web application, not a forged link from another site, is done by embedding a token based on a random 
+    # string stored in the session (which an attacker wouldn't know) in all forms and Ajax requests generated
+    # by Rails and then verifying the authenticity of that token in the controller.  Only HTML/JavaScript 
+    # requests are checked, so this will not protect your XML API (presumably you'll have a different 
+    # authentication scheme there anyway).  Also, GET requests are not protected as these should be 
+    # idempotent anyway.
     #
     # This is turned on with the <tt>protect_from_forgery</tt> method, which will check the token and raise an
-    # ActionController::InvalidAuthenticityToken if it doesn't match what was expected. You can customize the error message in
-    # production by editing public/422.html.  A call to this method in ApplicationController is generated by default in post-Rails 2.0
-    # applications.
+    # ActionController::InvalidAuthenticityToken if it doesn't match what was expected. You can customize the 
+    # error message in production by editing public/422.html.  A call to this method in ApplicationController is
+    # generated by default in post-Rails 2.0 applications.
     #
-    # The token parameter is named <tt>authenticity_token</tt> by default. If you are generating an HTML form manually (without the
-    # use of Rails' <tt>form_for</tt>, <tt>form_tag</tt> or other helpers), you have to include a hidden field named like that and
-    # set its value to what is returned by <tt>form_authenticity_token</tt>. Same applies to manually constructed Ajax requests. To
-    # make the token available through a global variable to scripts on a certain page, you could add something like this to a view:
+    # The token parameter is named <tt>authenticity_token</tt> by default. If you are generating an HTML form 
+    # manually (without the use of Rails' <tt>form_for</tt>, <tt>form_tag</tt> or other helpers), you have to 
+    # include a hidden field named like that and set its value to what is returned by 
+    # <tt>form_authenticity_token</tt>.
     #
-    #   <%= javascript_tag "window._token = '#{form_authenticity_token}'" %>
-    #
-    # Request forgery protection is disabled by default in test environment.  If you are upgrading from Rails 1.x, add this to
-    # config/environments/test.rb:
+    # Request forgery protection is disabled by default in test environment. If you are upgrading from Rails 
+    # 1.x, add this to config/environments/test.rb:
     #
     #   # Disable request forgery protection in test environment
     #   config.action_controller.allow_forgery_protection = false
@@ -57,7 +56,8 @@ module RequestForgeryProtection
     # * Keep your GET requests safe and idempotent.  More reading material:
     #   * http://www.xml.com/pub/a/2002/04/24/deviant.html
     #   * http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.1.1
-    # * Make sure the session cookies that Rails creates are non-persistent.  Check in Firefox and look for "Expires: at end of session"
+    #   * Make sure the session cookies that Rails creates are non-persistent.  Check in Firefox and look 
+    #     for "Expires: at end of session"
     #
     module ClassMethods
       # Turn on request forgery protection. Bear in mind that only non-GET, HTML/JavaScript requests are checked.
@@ -76,10 +76,7 @@ module ClassMethods
       # * <tt>:only/:except</tt> - Passed to the <tt>before_filter</tt> call.  Set which actions are verified.
       def protect_from_forgery(options = {})
         self.request_forgery_protection_token ||= :authenticity_token
-        before_filter :verify_authenticity_token, :only => options.delete(:only), :except => options.delete(:except)
-        if options[:secret] || options[:digest]
-          ActiveSupport::Deprecation.warn("protect_from_forgery only takes :only and :except options now. :digest and :secret have no effect", caller)
-        end
+        before_filter :verify_authenticity_token, options
       end
     end
 
@@ -88,31 +85,24 @@ def protect_from_forgery(options = {})
       def verify_authenticity_token
         verified_request? || raise(ActionController::InvalidAuthenticityToken)
       end
-      
+
       # Returns true or false if a request is verified.  Checks:
       #
       # * is the format restricted?  By default, only HTML requests are checked.
       # * is it a GET request?  Gets should be safe and idempotent
       # * Does the form_authenticity_token match the given token value from the params?
       def verified_request?
-        !protect_against_forgery?     ||
-          request.method == :get      ||
-          request.xhr?                ||
-          !verifiable_request_format? ||
+        !protect_against_forgery? || request.forgery_whitelisted? || 
           form_authenticity_token == params[request_forgery_protection_token]
       end
-    
-      def verifiable_request_format?
-        !request.content_type.nil? && request.content_type.verify_request?
-      end
-    
+
       # Sets the token value for the current session.
       def form_authenticity_token
         session[:_csrf_token] ||= ActiveSupport::SecureRandom.base64(32)
       end
 
       def protect_against_forgery?
-        allow_forgery_protection && request_forgery_protection_token
+        allow_forgery_protection
       end
   end
 end

actionpack/lib/action_dispatch/http/request.rb

@@ -97,6 +97,10 @@ def content_type
       end
     end
 
+    def forgery_whitelisted?
+      method == :get || xhr? || !(!content_type.nil? && content_type.verify_request?)
+    end
+
     def media_type
       content_type.to_s
     end