add rack-utf8_sanitizer gem

Gemfile

@@ -102,6 +102,8 @@ source 'https://rails-assets.org' do
   gem 'rails-assets-notifyjs'
 end
 
+gem 'rack-utf8_sanitizer'
+
 group :production do
   gem 'airbrake'
   #gem 'bluepill', '~> 0.0.60', require: false

Gemfile.lock

@@ -361,6 +361,8 @@ GEM
       rack (>= 1.0)
     rack-throttle (0.3.0)
       rack (>= 1.0.0)
+    rack-utf8_sanitizer (1.3.0)
+      rack (~> 1.0)
     rails (4.1.9)
       actionmailer (= 4.1.9)
       actionpack (= 4.1.9)
@@ -636,6 +638,7 @@ DEPENDENCIES
   protected_attributes
   puma
   rack-throttle (~> 0.3.0)
+  rack-utf8_sanitizer
   rails (= 4.1.9)
   rails-assets-notifyjs!
   rails3-generators

config/application.rb

@@ -21,6 +21,8 @@ module Rosa
 
     # Rate limit
     config.middleware.insert_before Rack::Runtime, ApiDefender
+    # Rack::UTF8Sanitizer is a Rack middleware which cleans up invalid UTF8 characters in request URI and headers.
+    config.middleware.insert 0, Rack::UTF8Sanitizer
 
     config.autoload_paths += %W(#{config.root}/lib)