Do not output an ETag header if response body is blank or when sendin…

…g files with send_file(... :xsendfile => true) [#1578 state:committed]

Signed-off-by: David Heinemeier Hansson <david@loudthinking.com>

actionpack/CHANGELOG

@@ -1,5 +1,7 @@
 *2.3.0 [Edge]*
 
+* Fixed that send_file shouldn't set an etag #1578 [Hongli Lai]
+
 * Allow users to opt out of the spoofing checks in Request#remote_ip.  Useful for sites whose traffic regularly triggers false positives. [Darren Boyd]
 
 * Deprecated formatted_polymorphic_url.  [Jeremy Kemper]

actionpack/lib/action_controller/response.rb

@@ -115,7 +115,11 @@ def etag?
     end
 
     def etag=(etag)
-      headers['ETag'] = %("#{Digest::MD5.hexdigest(ActiveSupport::Cache.expand_cache_key(etag))}")
+      if etag.blank?
+        headers.delete('ETag')
+      else
+        headers['ETag'] = %("#{Digest::MD5.hexdigest(ActiveSupport::Cache.expand_cache_key(etag))}")
+      end
     end
 
     def redirect(url, status)

actionpack/test/controller/render_test.rb

@@ -208,6 +208,10 @@ def heading
   def greeting
     # let's just rely on the template
   end
+
+  def blank_response
+    render :text => ' '
+  end
 
   def layout_test
     render :action => "hello_world"
@@ -1380,6 +1384,11 @@ def setup
     @request.host = "www.nextangle.com"
     @expected_bang_etag = etag_for(expand_key([:foo, 123]))
   end
+
+  def test_render_blank_body_shouldnt_set_etag
+    get :blank_response
+    assert !@response.etag?
+  end
 
   def test_render_200_should_set_etag
     get :render_hello_world_from_variable

actionpack/test/controller/send_file_test.rb

@@ -69,6 +69,7 @@ def test_x_sendfile_header
 
     assert_equal @controller.file_path, response.headers['X-Sendfile']
     assert response.body.blank?
+    assert !response.etag?
   end
 
   def test_data