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 the 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, index: 'index') @root = root.chomp('/') @compiled_root = /^#{Regexp.escape(root)}/ headers = cache_control && { 'Cache-Control' => cache_control } @file_server = ::Rack::File.new(@root, headers) @index = index end # Takes a path to a file. If the file is found, has valid encoding, and has # correct read permissions, the return value is a URI-escaped string # representing the filename. Otherwise, false is returned. # # Used by the `Static` class to check the existence of a valid file # in the server's `public/` directory (see Static#call). def match?(path) path = URI.parser.unescape(path) return false unless path.valid_encoding? path = Rack::Utils.clean_path_info path paths = [path, "#{path}#{ext}", "#{path}/#{@index}#{ext}"] if match = paths.detect { |p| path = File.join(@root, p.force_encoding('UTF-8'.freeze)) begin File.file?(path) && File.readable?(path) rescue SystemCallError false end } return ::Rack::Utils.escape(match) end end def call(env) path = env['PATH_INFO'] gzip_path = gzip_file_path(path) if gzip_path && gzip_encoding_accepted?(env) env['PATH_INFO'] = gzip_path status, headers, body = @file_server.call(env) if status == 304 return [status, headers, body] end 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_path return [status, headers, body] ensure env['PATH_INFO'] = path end private def ext ::ActionController::Base.default_static_extension end def content_type(path) ::Rack::Mime.mime_type(::File.extname(path), 'text/plain'.freeze) end def gzip_encoding_accepted?(env) env['HTTP_ACCEPT_ENCODING'] =~ /\bgzip\b/i end def gzip_file_path(path) can_gzip_mime = content_type(path) =~ /\A(?:text\/|application\/javascript)/ gzip_path = "#{path}.gz" if can_gzip_mime && File.exist?(File.join(@root, ::Rack::Utils.unescape(gzip_path))) gzip_path else false end 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, index: 'index') @app = app @file_handler = FileHandler.new(path, cache_control, index: index) end def call(env) case env['REQUEST_METHOD'] when 'GET', 'HEAD' path = env['PATH_INFO'].chomp('/'.freeze) if match = @file_handler.match?(path) env['PATH_INFO'] = match return @file_handler.call(env) end end @app.call(env) end end end