Rack::Attack::Recaptcha

rack-attack-recaptcha allows you to easily respond to requests that get throttled by rack-attack by showing a captcha instead of the "Retry later" message you get with rack-attack. This will allow you to keep your app functional even in the event of an attack from a public IP, for example, since legit users who share that IP will still be able to access the app by entering a captcha.

rack-attack-recaptcha works similarly to recaptch. It gives you 2 helper methods (recaptcha_tags_if_under_attack for views and verify_recaptcha_if_under_attack for controllers) which will simply call recaptcha_tags or verify_recaptcha (provided by recaptcha) accordingly when the current request should be throttled. If the request is not part of an attack, verify_tags_if_under_attack will display nothing and verify_recaptcha_if_under_attack will simply return true.

Add this line to your application's Gemfile:

gem 'rack-attack-recaptcha'

And then execute:

$ bundle

Tell your app to use the Rack::Attack middleware. For Rails 3+ apps:

# In config/application.rb
config.middleware.use Rack::Attack::Recaptcha

To setup Recaptcha throttles, you should specify the throttle's type to be :recaptcha as shown here:

Rack::Attack.throttle('req/ip', :limit => 5, :period => 1.second, :type => :recaptcha) do |req|
  req.ip
end

Check out rack-attack's's wiki for more details on setting throttles. To setup Recaptcha credentials, check out recaptcha's wiki.

After you've setup your Recaptcha credentials and defined some throttles, add recaptcha_tags_if_under_attack to each form you want to protect. Place it where you want the Recaptcha widget to appear.

Example:

# app/views/foos/foo.html.erb

<%= form_for @foo do |f| %>
  # ... additional lines truncated for brevity ...
  <%= recaptcha_tags_if_under_attack %>
  # ... additional lines truncated for brevity ...
<% end %>

(If the request is legit, recaptcha_tags_if_under_attack will render nothing.)

Now add verify_recaptcha_if_under_attack logic to each form action that you've protected:

# app/controllers/foos_controller.rb

def create
  if verify_recaptcha_if_under_attack && @foo.save
    # ...
  else
    # ...
  end
end

(If the request is legit, verify_recaptcha_if_under_attack won't actually check the captcha and will simply return true)

Note that recaptcha_tags_if_under_attack and verify_recaptcha_if_under_attack pass all options to recaptcha_tags and verify_recaptcha so you can use all the configuration values that are provided by recaptcha. (See recaptcha's documentation for a list of all the configuration options)

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