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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)
req = ActionDispatch::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.call(req.env)
end
end
@app.call(req.env)
end
end
end
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