Added a configuration setting:

  config.action_controller.default_asset_host_protocol

It's best to leave this unset.

When unset the :request protocol is used whenever it can be and
:relative is used in the other situations.

When set to :request then assets hosts will be disabled when there
is no request in scope and will use the request protocol whenever a
request is in scope.

If set to :relative, then a relative protocol is always used except
for stylesheet link tags which must use the :request protocol to
avoid double downloads in IE6&7.

Conflicts:

	actionpack/lib/sprockets/helpers/rails_helper.rb
	actionpack/test/template/sprockets_helper_test.rb

actionpack/lib/action_view/asset_paths.rb

@@ -19,7 +19,7 @@ def initialize(config, controller = nil)
     # When :relative (default), the protocol will be determined by the client using current protocol
     # When :request, the protocol will be the request protocol
     # Otherwise, the protocol is used (E.g. :http, :https, etc)
-    def compute_public_path(source, dir, ext = nil, include_host = true, protocol = :relative)
+    def compute_public_path(source, dir, ext = nil, include_host = true, protocol = nil)
       source = source.to_s
       return source if is_uri?(source)
 
@@ -58,16 +58,20 @@ def has_request?
       controller.respond_to?(:request)
     end
 
-    def rewrite_host_and_protocol(source, protocol = :relative)
+    def rewrite_host_and_protocol(source, protocol = nil)
       host = compute_asset_host(source)
       if host && !is_uri?(host)
-        host = "#{compute_protocol(protocol)}#{host}"
+        if (protocol || default_protocol) == :request && !has_request?
+          host = nil
+        else
+          host = "#{compute_protocol(protocol)}#{host}"
+        end
       end
       host.nil? ? source : "#{host}#{source}"
     end
 
     def compute_protocol(protocol)
-      protocol ||= :relative
+      protocol ||= default_protocol
       case protocol
       when :relative
         "//"
@@ -81,6 +85,12 @@ def compute_protocol(protocol)
       end
     end
 
+    def default_protocol
+      protocol = @config.action_controller.default_asset_host_protocol if @config.action_controller.present?
+      protocol ||= @config.default_asset_host_protocol
+      protocol || (has_request? ? :request : :relative)
+    end
+
     def invalid_asset_host!(help_message)
       raise ActionController::RoutingError, "This asset host cannot be computed without a request in scope. #{help_message}"
     end

actionpack/lib/action_view/helpers/asset_tag_helpers/asset_include_tag.rb

@@ -60,8 +60,8 @@ def include_tag(*sources)
 
         private
 
-          def path_to_asset(source, protocol = :relative)
-            asset_paths.compute_public_path(source, asset_name.to_s.pluralize, extension, true, protocol)
+          def path_to_asset(source, include_host = true, protocol = nil)
+            asset_paths.compute_public_path(source, asset_name.to_s.pluralize, extension, include_host, protocol)
           end
 
           def path_to_asset_source(source)

actionpack/lib/action_view/helpers/asset_tag_helpers/stylesheet_tag_helpers.rb

@@ -16,7 +16,8 @@ def extension
         end
 
         def asset_tag(source, options)
-          tag("link", { "rel" => "stylesheet", "type" => Mime::CSS, "media" => "screen", "href" => ERB::Util.html_escape(path_to_asset(source, :request)) }.merge(options), false, false)
+          # We force the :request protocol here to avoid a double-download bug in IE7 and IE8
+          tag("link", { "rel" => "stylesheet", "type" => Mime::CSS, "media" => "screen", "href" => ERB::Util.html_escape(path_to_asset(source, true, :request)) }.merge(options), false, false)
         end
 
         def custom_dir

actionpack/lib/sprockets/helpers/rails_helper.rb

@@ -64,9 +64,9 @@ def stylesheet_link_tag(*sources)
         end.join("\n").html_safe
       end
 
-      def asset_path(source, default_ext = nil, body = false, protocol = :relative)
+      def asset_path(source, default_ext = nil, body = false, protocol = nil)
         source = source.logical_path if source.respond_to?(:logical_path)
-        path = asset_paths.compute_public_path(source, 'assets', default_ext, protocol)
+        path = asset_paths.compute_public_path(source, 'assets', default_ext, true, protocol)
         body ? "#{path}?body=1" : path
       end
 
@@ -77,7 +77,7 @@ def debug_assets?
       end
 
       class AssetPaths < ::ActionView::AssetPaths #:nodoc:
-        def compute_public_path(source, dir, ext=nil, include_host=true, protocol = :relative)
+        def compute_public_path(source, dir, ext=nil, include_host=true, protocol = nil)
           super(source, Rails.application.config.assets.prefix, ext, include_host, protocol)
         end
 

actionpack/test/template/asset_tag_helper_test.rb

@@ -1093,11 +1093,21 @@ def test_should_ignore_relative_root_path_on_complete_url
   def test_should_compute_proper_path_with_asset_host
     @controller.config.asset_host = "assets.example.com"
     assert_dom_equal(%(<link href="http://www.example.com/collaboration/hieraki" rel="alternate" title="RSS" type="application/rss+xml" />), auto_discovery_link_tag)
-    assert_dom_equal(%(//assets.example.com/collaboration/hieraki/javascripts/xmlhr.js), javascript_path("xmlhr"))
+    assert_dom_equal(%(gopher://assets.example.com/collaboration/hieraki/javascripts/xmlhr.js), javascript_path("xmlhr"))
     assert_dom_equal(%(gopher://assets.example.com/collaboration/hieraki/stylesheets/style.css), stylesheet_path("style"))
-    assert_dom_equal(%(//assets.example.com/collaboration/hieraki/images/xml.png), image_path("xml.png"))
-    assert_dom_equal(%(<img alt="Mouse" onmouseover="this.src='//assets.example.com/collaboration/hieraki/images/mouse_over.png'" onmouseout="this.src='//assets.example.com/collaboration/hieraki/images/mouse.png'" src="//assets.example.com/collaboration/hieraki/images/mouse.png" />), image_tag("mouse.png", :mouseover => "/images/mouse_over.png"))
-    assert_dom_equal(%(<img alt="Mouse2" onmouseover="this.src='//assets.example.com/collaboration/hieraki/images/mouse_over2.png'" onmouseout="this.src='//assets.example.com/collaboration/hieraki/images/mouse2.png'" src="//assets.example.com/collaboration/hieraki/images/mouse2.png" />), image_tag("mouse2.png", :mouseover => image_path("mouse_over2.png")))
+    assert_dom_equal(%(gopher://assets.example.com/collaboration/hieraki/images/xml.png), image_path("xml.png"))
+    assert_dom_equal(%(<img alt="Mouse" onmouseover="this.src='gopher://assets.example.com/collaboration/hieraki/images/mouse_over.png'" onmouseout="this.src='gopher://assets.example.com/collaboration/hieraki/images/mouse.png'" src="gopher://assets.example.com/collaboration/hieraki/images/mouse.png" />), image_tag("mouse.png", :mouseover => "/images/mouse_over.png"))
+    assert_dom_equal(%(<img alt="Mouse2" onmouseover="this.src='gopher://assets.example.com/collaboration/hieraki/images/mouse_over2.png'" onmouseout="this.src='gopher://assets.example.com/collaboration/hieraki/images/mouse2.png'" src="gopher://assets.example.com/collaboration/hieraki/images/mouse2.png" />), image_tag("mouse2.png", :mouseover => image_path("mouse_over2.png")))
+  end
+
+  def test_should_compute_proper_path_with_asset_host_and_default_protocol
+    @controller.config.asset_host = "assets.example.com"
+    @controller.config.default_asset_host_protocol = :request
+    assert_dom_equal(%(gopher://assets.example.com/collaboration/hieraki/javascripts/xmlhr.js), javascript_path("xmlhr"))
+    assert_dom_equal(%(gopher://assets.example.com/collaboration/hieraki/stylesheets/style.css), stylesheet_path("style"))
+    assert_dom_equal(%(gopher://assets.example.com/collaboration/hieraki/images/xml.png), image_path("xml.png"))
+    assert_dom_equal(%(<img alt="Mouse" onmouseover="this.src='gopher://assets.example.com/collaboration/hieraki/images/mouse_over.png'" onmouseout="this.src='gopher://assets.example.com/collaboration/hieraki/images/mouse.png'" src="gopher://assets.example.com/collaboration/hieraki/images/mouse.png" />), image_tag("mouse.png", :mouseover => "/images/mouse_over.png"))
+    assert_dom_equal(%(<img alt="Mouse2" onmouseover="this.src='gopher://assets.example.com/collaboration/hieraki/images/mouse_over2.png'" onmouseout="this.src='gopher://assets.example.com/collaboration/hieraki/images/mouse2.png'" src="gopher://assets.example.com/collaboration/hieraki/images/mouse2.png" />), image_tag("mouse2.png", :mouseover => image_path("mouse_over2.png")))
   end
 
   def test_should_ignore_asset_host_on_complete_url
@@ -1117,12 +1127,12 @@ def test_should_wildcard_asset_host_between_zero_and_four
 
   def test_asset_host_without_protocol_should_be_protocol_relative
     @controller.config.asset_host = 'a.example.com'
-    assert_equal '//a.example.com/collaboration/hieraki/images/xml.png', image_path('xml.png')
+    assert_equal 'gopher://a.example.com/collaboration/hieraki/images/xml.png', image_path('xml.png')
   end
 
   def test_asset_host_without_protocol_should_be_protocol_relative_even_if_path_present
     @controller.config.asset_host = 'a.example.com/files/go/here'
-    assert_equal '//a.example.com/files/go/here/collaboration/hieraki/images/xml.png', image_path('xml.png')
+    assert_equal 'gopher://a.example.com/files/go/here/collaboration/hieraki/images/xml.png', image_path('xml.png')
   end
 
   def test_assert_css_and_js_of_the_same_name_return_correct_extension

actionpack/test/template/sprockets_helper_test.rb

@@ -62,11 +62,18 @@ def url_for(*args)
       asset_path("http://www.example.com/video/play.mp4")
   end
 
-  test "with a simple asset host the url should be protocol relative" do
+  test "with a simple asset host the url should default to protocol relative" do
     @controller.config.asset_host = "assets-%d.example.com"
     assert_match %r{//assets-\d.example.com/assets/logo-[0-9a-f]+.png},
       asset_path("logo.png")
   end
+
+  test "with a simple asset host the url can be changed to use the request protocol" do
+    @controller.config.asset_host = "assets-%d.example.com"
+    @controller.config.default_asset_host_protocol = :request
+    assert_match %r{http://assets-\d.example.com/assets/logo-[0-9a-f]+.png},
+      asset_path("logo.png")
+  end
   
   test "With a proc asset host that returns no protocol the url should be protocol relative" do
     @controller.config.asset_host = Proc.new do |asset|
@@ -103,6 +110,16 @@ def url_for(*args)
     end
   end
 
+  test "stylesheets served without a controller in do not use asset hosts when the default protocol is :request" do
+    remove_instance_variable("@controller")
+    @config.action_controller.asset_host = "assets-%d.example.com"
+    @config.action_controller.default_asset_host_protocol = :request
+    @config.action_controller.perform_caching = true
+
+    assert_equal "/assets/logo-9c0a079bdd7701d7e729bd956823d153.png",
+      asset_path("logo.png")
+  end
+
   test "asset path with relative url root" do
     @controller.config.relative_url_root = "/collaboration/hieraki"
     assert_equal "/collaboration/hieraki/images/logo.gif",