Merge pull request #2334 from 4Science/fix-bistream-download-cache

fix for bitstreams are not visible to crawlers when caching is enabled

server.ts

@@ -461,6 +461,8 @@ function saveToCache(req, page: any) {
     const key = getCacheKey(req);
     // Avoid caching "/reload/[random]" paths (these are hard refreshes after logout)
     if (key.startsWith('/reload')) { return; }
+    // Avoid caching not successful responses (status code different from 2XX status)
+    if (hasNotSucceeded(req.res.statusCode)) { return; }
 
     // Retrieve response headers to save, if any
     const headers = retrieveHeaders(req.res);
@@ -479,6 +481,15 @@ function saveToCache(req, page: any) {
   }
 }
 
+/**
+ * Check if status code is different from 2XX
+ * @param statusCode
+ */
+function hasNotSucceeded(statusCode) {
+  const rgx = new RegExp(/^20+/);
+  return !rgx.test(statusCode)
+}
+
 function retrieveHeaders(response) {
   const headers = Object.create({});
   if (Array.isArray(environment.cache.serverSide.headers) && environment.cache.serverSide.headers.length > 0) {