1 files changed, 59 insertions, 14 deletions

diff --git a/actionpack/lib/action_dispatch/middleware/static.rb b/actionpack/lib/action_dispatch/middleware/static.rb
index 2764584fe9..a3e8126ace 100644
--- a/actionpack/lib/action_dispatch/middleware/static.rb
+++ b/actionpack/lib/action_dispatch/middleware/static.rb
@@ -2,12 +2,23 @@ require 'rack/utils'
 require 'active_support/core_ext/uri'
 
 module ActionDispatch
+  # This middleware returns a file's contents from disk in the body response.
+  # When initialized it can accept an optional 'Cache-Control' header which
+  # will be set when a response containing a file's contents is delivered.
+  #
+  # This middleware will render the file specified in `env["PATH_INFO"]`
+  # where the base path is in the +root+ directory. For example if the +root+
+  # is set to `public/` then a request with `env["PATH_INFO"]` of
+  # `assets/application.js` will return a response with contents of a file
+  # located at `public/assets/application.js` if the file exists. If the file
+  # does not exist a 404 "File not Found" response will be returned.
   class FileHandler
     def initialize(root, cache_control)
       @root          = root.chomp('/')
       @compiled_root = /^#{Regexp.escape(root)}/
-      headers = cache_control && { 'Cache-Control' => cache_control }
-      @file_server   = ::Rack::File.new(@root, headers)
+      headers        = {}
+      headers['Cache-Control'] = cache_control if cache_control
+      @file_server = ::Rack::File.new(@root, headers)
     end
 
     def match?(path)
@@ -26,25 +37,59 @@ module ActionDispatch
     end
 
     def call(env)
-      @file_server.call(env)
+      path             = env['PATH_INFO']
+      gzip_file_exists = gzip_file_exists?(path)
+      if gzip_file_exists && gzip_encoding_accepted?(env)
+        env['PATH_INFO'] = "#{path}.gz"
+        status, headers, body       = @file_server.call(env)
+        headers['Content-Encoding'] = 'gzip'
+        headers['Content-Type']     = content_type(path)
+      else
+        status, headers, body = @file_server.call(env)
+      end
+
+      headers['Vary'] = 'Accept-Encoding' if gzip_file_exists
+      return [status, headers, body]
     end
 
-    def ext
-      @ext ||= begin
-        ext = ::ActionController::Base.default_static_extension
-        "{,#{ext},/index#{ext}}"
+    private
+      def ext
+        @ext ||= begin
+          ext = ::ActionController::Base.default_static_extension
+          "{,#{ext},/index#{ext}}"
+        end
       end
-    end
 
-    def unescape_path(path)
-      URI.parser.unescape(path)
-    end
+      def unescape_path(path)
+        URI.parser.unescape(path)
+      end
 
-    def escape_glob_chars(path)
-      path.gsub(/[*?{}\[\]]/, "\\\\\\&")
-    end
+      def escape_glob_chars(path)
+        path.gsub(/[*?{}\[\]]/, "\\\\\\&")
+      end
+
+      def content_type(path)
+        ::Rack::Mime.mime_type(::File.extname(path), 'text/plain')
+      end
+
+      def gzip_encoding_accepted?(env)
+        env['HTTP_ACCEPT_ENCODING'] =~ /\bgzip\b/
+      end
+
+      def gzip_file_exists?(path)
+        File.exist?(File.join(@root, "#{::Rack::Utils.unescape(path)}.gz"))
+      end
   end
 
+  # This middleware will attempt to return the contents of a file's body from
+  # disk in the response.  If a file is not found on disk, the request will be
+  # delegated to the application stack. This middleware is commonly initialized
+  # to serve assets from a server's `public/` directory.
+  #
+  # This middleware verifies the path to ensure that only files
+  # living in the root directory can be rendered. A request cannot
+  # produce a directory traversal using this middleware. Only 'GET' and 'HEAD'
+  # requests will result in a file being returned.
   class Static
     def initialize(app, path, cache_control=nil)
       @app = app