Fix CSP for disqus and Google Analytics

This commit should fix existing problems with Disqus and Google
Analytics enabled in the meta-yaml section of a note.

Before this commit they were blocked by the strict CSP. It's still
possible to disable the added directives using `addDisqus` and
`addGoogleAnalytics` in the `csp` config section.

They are enabled by default to prevent breaking changes.

Signed-off-by: Sheogorath <sheogorath@shivering-isles.com>

lib/csp.js

@@ -5,7 +5,7 @@ var CspStrategy = {}
 
 var defaultDirectives = {
   defaultSrc: ['\'self\''],
-  scriptSrc: ['\'self\'', 'vimeo.com', 'https://gist.github.com', 'www.slideshare.net', 'https://query.yahooapis.com', 'https://*.disqus.com', '\'unsafe-eval\''],
+  scriptSrc: ['\'self\'', 'vimeo.com', 'https://gist.github.com', 'www.slideshare.net', 'https://query.yahooapis.com', '\'unsafe-eval\''],
   // ^ TODO: Remove unsafe-eval - webpack script-loader issues https://github.com/hackmdio/hackmd/issues/594
   imgSrc: ['*'],
   styleSrc: ['\'self\'', '\'unsafe-inline\'', 'https://assets-cdn.github.com'], // unsafe-inline is required for some libs, plus used in views
@@ -22,11 +22,23 @@ var cdnDirectives = {
   fontSrc: ['https://cdnjs.cloudflare.com', 'https://fonts.gstatic.com']
 }
 
+var disqusDirectives = {
+  scriptSrc: ['https://*.disqus.com', 'https://*.disquscdn.com'],
+  styleSrc: ['https://*.disquscdn.com'],
+  fontSrc: ['https://*.disquscdn.com']
+}
+
+var googleAnalyticsDirectives = {
+  scriptSrc: ['https://www.google-analytics.com']
+}
+
 CspStrategy.computeDirectives = function () {
   var directives = {}
   mergeDirectives(directives, config.csp.directives)
   mergeDirectivesIf(config.csp.addDefaults, directives, defaultDirectives)
   mergeDirectivesIf(config.useCDN, directives, cdnDirectives)
+  mergeDirectivesIf(config.csp.addDisqus, directives, disqusDirectives)
+  mergeDirectivesIf(config.csp.addGoogleAnalytics, directives, googleAnalyticsDirectives)
   if (!areAllInlineScriptsAllowed(directives)) {
     addInlineScriptExceptions(directives)
   }