FIX: canonical url should not use the CDN

app/controllers/topics_controller.rb

@@ -59,7 +59,7 @@ class TopicsController < ApplicationController
 
     perform_show_response
 
-    canonical_url absolute(@topic_view.canonical_path)
+    canonical_url absolute_without_cdn(@topic_view.canonical_path)
   end
 
   def wordpress

lib/url_helper.rb

@@ -6,8 +6,12 @@ module UrlHelper
     url.start_with?(Discourse.asset_host || Discourse.base_url_no_prefix)
   end
 
-  def absolute(url)
-    url =~ /^\/[^\/]/ ? (Discourse.asset_host || Discourse.base_url_no_prefix) + url : url
+  def absolute(url, cdn = Discourse.asset_host)
+    url =~ /^\/[^\/]/ ? (cdn || Discourse.base_url_no_prefix) + url : url
+  end
+
+  def absolute_without_cdn(url)
+    absolute(url, nil)
   end
 
   def schemaless(url)

spec/components/url_helper_spec.rb

@@ -33,10 +33,24 @@ describe UrlHelper do
       helper.absolute("http://www.discourse.org").should == "http://www.discourse.org"
     end
 
-    it "changes a relative url to an absolute one" do
+    it "changes a relative url to an absolute one using base url by default" do
       helper.absolute("/path/to/file").should == "http://test.localhost/path/to/file"
     end
 
+    it "changes a relative url to an absolute one using the cdn when enabled" do
+      Rails.configuration.action_controller.stubs(:asset_host).returns("http://my.cdn.com")
+      helper.absolute("/path/to/file").should == "http://my.cdn.com/path/to/file"
+    end
+
+  end
+
+  describe "#absolute_without_cdn" do
+
+    it "changes a relative url to an absolute one using base url even when cdn is enabled" do
+      Rails.configuration.action_controller.stubs(:asset_host).returns("http://my.cdn.com")
+      helper.absolute_without_cdn("/path/to/file").should == "http://test.localhost/path/to/file"
+    end
+
   end
 
   describe "#schemaless" do