Fix uncaught query param encoding errors (#12741)

config/application.rb

@@ -7,6 +7,7 @@ require 'rails/all'
 Bundler.require(*Rails.groups)
 
 require_relative '../app/lib/exceptions'
+require_relative '../app/middleware/handle_bad_encoding_middleware'
 require_relative '../lib/paperclip/lazy_thumbnail'
 require_relative '../lib/paperclip/gif_transcoder'
 require_relative '../lib/paperclip/video_transcoder'
@@ -118,6 +119,7 @@ module Mastodon
 
     config.active_job.queue_adapter = :sidekiq
 
+    config.middleware.insert_before Rack::Runtime, HandleBadEncodingMiddleware
     config.middleware.use Rack::Attack
     config.middleware.use Rack::Deflater
 

config/initializers/rack_attack.rb

@@ -46,10 +46,7 @@ class Rack::Attack
 
   PROTECTED_PATHS_REGEX = Regexp.union(PROTECTED_PATHS.map { |path| /\A#{Regexp.escape(path)}/ })
 
-  # Always allow requests from localhost
-  # (blocklist & throttles are skipped)
   Rack::Attack.safelist('allow from localhost') do |req|
-    # Requests are allowed if the return value is truthy
     req.remote_ip == '127.0.0.1' || req.remote_ip == '::1'
   end