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 optional HTTP headers, 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, index: "index", headers: {}) @root = root.chomp("/") @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 = ::Rack::Utils.unescape_path path return false unless ::Rack::Utils.valid_path? path 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(Encoding::UTF_8)) begin File.file?(path) && File.readable?(path) rescue SystemCallError false end } return ::Rack::Utils.escape_path(match) end end def call(env) serve(Rack::Request.new(env)) end def serve(request) path = request.path_info gzip_path = gzip_file_path(path) if gzip_path && gzip_encoding_accepted?(request) request.path_info = gzip_path status, headers, body = @file_server.call(request.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(request.env) end headers["Vary"] = "Accept-Encoding" if gzip_path return [status, headers, body] ensure request.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?(request) request.accept_encoding.any? { |enc, quality| enc =~ /\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_path(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, index: "index", headers: {}) @app = app @file_handler = FileHandler.new(path, index: index, headers: headers) end def call(env) req = Rack::Request.new env if req.get? || req.head? path = req.path_info.chomp("/".freeze) if match = @file_handler.match?(path) req.path_info = match return @file_handler.serve(req) end end @app.call(req.env) end end end