SECURITY: add rate limiting to anon JS error reporting

This adds a 1 minute rate limit to all JS error reporting per IP. Previously
we would only use the global rate limit.

This also introduces DISCOURSE_ENABLE_JS_ERROR_REPORTING, if it is set to
false then no JS error reporting will be allowed on the site.

Gemfile.lock

@@ -169,7 +169,7 @@ GEM
     logstash-event (1.2.02)
     logstash-logger (0.26.1)
       logstash-event (~> 1.2)
-    logster (2.3.1)
+    logster (2.3.2)
     loofah (2.2.3)
       crass (~> 1.0.2)
       nokogiri (>= 1.5.9)

app/assets/javascripts/preload-application-data.js.no-module.es6

@@ -12,6 +12,9 @@
 
   var setupData = document.getElementById("data-discourse-setup").dataset;
 
+  window.Logster = window.Logster || {};
+  window.Logster.enabled = setupData.enableJsErrorReporting === "true";
+
   Discourse.CDN = setupData.cdn;
   Discourse.BaseUrl = setupData.baseUrl;
   Discourse.BaseUri = setupData.baseUri;

app/helpers/application_helper.rb

@@ -475,6 +475,7 @@ module ApplicationHelper
       disable_custom_css: loading_admin?,
       highlight_js_path: HighlightJs.path,
       svg_sprite_path: SvgSprite.path(theme_ids),
+      enable_js_error_reporting: GlobalSetting.enable_js_error_reporting,
     }
 
     if Rails.env.development?

config/discourse_defaults.conf

@@ -256,3 +256,6 @@ maxmind_backup_path =
 # X-Queue-Time: 1.01
 enable_performance_http_headers = false
 
+# gather JavaScript errors from clients (rate limited to 1 error per IP per minute)
+enable_js_error_reporting = true
+

config/initializers/100-logster.rb

@@ -104,6 +104,7 @@ Logster.config.subdirectory = "#{GlobalSetting.relative_url_root}/logs"
 
 Logster.config.application_version = Discourse.git_version
 Logster.config.enable_custom_patterns_via_ui = true
+Logster.config.enable_js_error_reporting = GlobalSetting.enable_js_error_reporting
 
 store = Logster.store
 redis = Logster.store.redis