Rack::UTF8Sanitizer

Rack::UTF8Sanitizer is a Rack middleware which cleans up invalid UTF8 characters in request URI and headers.

Installation

Add this line to your application's Gemfile:

gem 'rack-utf8_sanitizer'

And then execute:

$ bundle

Or install it yourself as:

$ gem install rack-utf8_sanitizer

For Rails, add this to your application.rb:

config.middleware.insert 0, Rack::UTF8Sanitizer

For Rack apps, add this to config.ru:

use Rack::UTF8Sanitizer

Usage

Rack::UTF8Sanitizer divides all keys in the Rack environment in two distinct groups: keys which contain raw data and the ones with percent-encoded data. The fields which are treated as percent-encoded are: SCRIPT_NAME, REQUEST_PATH, REQUEST_URI, PATH_INFO, QUERY_STRING, HTTP_REFERER.

The generic sanitization algorithm is as follows:

1. Force the encoding to UTF-8.
2. If the result contains invalid characters:
   1. Force the encoding to ASCII8-BIT.
   2. Re-encode it as UTF-8, replacing invalid and undefined characters as U+FFFD.

For fields with "raw data", the algorithm is applied once and the (UTF-8 encoded) result is left in the environment.

For fields with "percent-encoded data", the algorithm is applied twice to catch both invalid characters appearing as-is and invalid characters appearing in the percent encoding. The percent encoded, ASCII-8BIT encoded result is left in the environment.

Sanitizable content types

The default content types to be sanitized are 'text/plain', 'application/x-www-form-urlencoded', 'application/json', 'text/javascript'. You may wish to modify this, for example if your app accepts specific or custom media types in the CONTENT_TYPE header. If you want to change the sanitizable content types, you can pass options when using Rack::UTF8Sanitizer.

To add sanitizable content types to the list of defaults, pass the additional_content_types options when using Rack::UTF8Sanitizer, e.g.

config.middleware.insert 0, Rack::UTF8Sanitizer, additional_content_types: ['application/vnd.api+json']

To explicitly set sanitizable content types and override the defaults, use the sanitizable_content_types option:

config.middleware.insert 0, Rack::UTF8Sanitizer, sanitizable_content_types: ['application/vnd.api+json']

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request

To run the tests, run rake spec in the project directory.