Refactor out Dir.glob from ActionDispatch::Static

Dir.glob can be a security concern. The original use was to provide logic of fallback files. Example a request to `/` should render the file from `/public/index.html`. We can replace the dir glob with the specific logic it represents. The glob {,index,index.html} will look for the current path, then in the directory of the path with index file and then in the directory of the path with index.html. This PR replaces the glob logic by manually checking each potential match. Best case scenario this results in one less file API request, worst case, this has one more file API request.

Related to #16464

Update: added a test for when a file of a given name (`public/bar.html` and a directory `public/bar` both exist in the same root directory. Changed logic to accommodate this scenario.

1 files changed, 5 insertions, 20 deletions

diff --git a/actionpack/lib/action_dispatch/middleware/static.rb b/actionpack/lib/action_dispatch/middleware/static.rb
index 0733132277..e66c21ef85 100644
--- a/actionpack/lib/action_dispatch/middleware/static.rb
+++ b/actionpack/lib/action_dispatch/middleware/static.rb
@@ -21,17 +21,13 @@ module ActionDispatch
     end
 
     def match?(path)
-      path = unescape_path(path)
+      path = URI.parser.unescape(path)
       return false unless path.valid_encoding?
 
-      full_path = path.empty? ? @root : File.join(@root, escape_glob_chars(path))
-      paths = "#{full_path}#{ext}"
+      paths = [path, "#{path}#{ext}", "#{path}/index#{ext}"]
 
-      matches = Dir[paths]
-      match = matches.detect { |m| File.file?(m) }
-      if match
-        match.sub!(@compiled_root, '')
-        ::Rack::Utils.escape(match)
+      if match = paths.detect {|p| File.file?(File.join(@root, p)) }
+        return ::Rack::Utils.escape(match)
       end
     end
 
@@ -57,18 +53,7 @@ module ActionDispatch
 
     private
       def ext
-        @ext ||= begin
-          ext = ::ActionController::Base.default_static_extension
-          "{,#{ext},/index#{ext}}"
-        end
-      end
-
-      def unescape_path(path)
-        URI.parser.unescape(path)
-      end
-
-      def escape_glob_chars(path)
-        path.gsub(/[*?{}\[\]]/, "\\\\\\&")
+        ::ActionController::Base.default_static_extension
       end
 
       def content_type(path)