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# frozen_string_literal: true
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 <tt>env["PATH_INFO"]</tt>
# where the base path is in the +root+ directory. For example, if the +root+
# is set to +public/+, then a request with <tt>env["PATH_INFO"]</tt> 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("/").b
@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
return ::Rack::Utils.escape_path(path).b if file_readable?(path)
path_with_ext = path + ext
return ::Rack::Utils.escape_path(path_with_ext).b if file_readable?(path_with_ext)
path << "/" << @index << ext
return ::Rack::Utils.escape_path(path).b if file_readable?(path)
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
[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")
end
def gzip_encoding_accepted?(request)
request.accept_encoding.any? { |enc, quality| /\bgzip\b/i.match?(enc) }
end
def gzip_file_path(path)
can_gzip_mime = /\A(?:text\/|application\/javascript)/.match?(content_type(path))
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
def file_readable?(path)
file_stat = File.stat(File.join(@root, path.b))
rescue SystemCallError
false
else
file_stat.file? && file_stat.readable?
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("/")
if match = @file_handler.match?(path)
req.path_info = match
return @file_handler.serve(req)
end
end
@app.call(req.env)
end
end
end
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