FIX: don't index urls to local files

app/services/search_indexer.rb

@@ -167,6 +167,8 @@ def self.index(obj, force: false)
 
   class HtmlScrubber < Nokogiri::XML::SAX::Document
 
+    DIACRITICS ||= /([\u0300-\u036f]|[\u1AB0-\u1AFF]|[\u1DC0-\u1DFF]|[\u20D0-\u20FF])/
+
     def self.strip_diacritics(str)
       s = str.unicode_normalize(:nfkd)
       s.gsub!(DIACRITICS, "")
@@ -196,12 +198,12 @@ def start_element(_, attributes = [])
       attributes = Hash[*attributes.flatten]
 
       ATTRIBUTES.each do |name|
-        characters(attributes[name]) if attributes[name].present?
+        if attributes[name].present?
+          characters(attributes[name]) unless name == "href" && UrlHelper.is_local(attributes[name])
+        end
       end
     end
 
-    DIACRITICS ||= /([\u0300-\u036f]|[\u1AB0-\u1AFF]|[\u1DC0-\u1DFF]|[\u20D0-\u20FF])/
-
     def characters(str)
       str = HtmlScrubber.strip_diacritics(str) if @strip_diacritics
       scrubbed << " #{str} "

spec/services/search_indexer_spec.rb

@@ -2,6 +2,7 @@
 
 describe SearchIndexer do
   let(:post_id) { 99 }
+
   it 'correctly indexes chinese' do
     SiteSetting.default_locale = 'zh_CN'
     data = "你好世界"
@@ -37,6 +38,27 @@
     expect(scrubbed).to eq(" HELLO Heterogeneite Здравствуите هتاف للترحيب 你好 ")
   end
 
+  it "doesn't index local files" do
+    html = <<~HTML
+      <p><img src="https://www.discourse.org/logo.png" alt="Discourse"></p>
+      <p><img src="#{Discourse.base_url_no_prefix}/uploads/episodeinteractive/original/3X/0/f/0f40b818356bdc1d80acfa905034e95cfd112a3a.png" alt="51%20PM" width="289" height="398"></p>
+      <div class="lightbox-wrapper">
+        <a class="lightbox" href="#{Discourse.base_url_no_prefix}/uploads/episodeinteractive/original/3X/1/6/16790095df3baf318fb2eb1d7e5d7860dc45d48b.jpg" data-download-href="#{Discourse.base_url_no_prefix}/uploads/episodeinteractive/16790095df3baf318fb2eb1d7e5d7860dc45d48b" title="Untitled design (21).jpg" rel="nofollow noopener">
+          <img src="#{Discourse.base_url_no_prefix}/uploads/episodeinteractive/optimized/3X/1/6/16790095df3baf318fb2eb1d7e5d7860dc45d48b_1_563x500.jpg" alt="Untitled%20design%20(21)" width="563" height="500">
+          <div class="meta">
+            <span class="filename">Untitled design (21).jpg</span>
+            <span class="informations">1280x1136 472 KB</span>
+            <span class="expand"></span>
+          </div>
+        </a>
+      </div>
+    HTML
+
+    scrubbed = SearchIndexer::HtmlScrubber.scrub(html).gsub(/\s+/, " ")
+
+    expect(scrubbed).to eq(" Discourse 51%20PM Untitled design (21).jpg Untitled%20design%20(21) Untitled design (21).jpg 1280x1136 472 KB ")
+  end
+
   it 'correctly indexes a post according to version' do
     # Preparing so that they can be indexed to right version
     SearchIndexer.update_posts_index(post_id, "dummy", "", nil, nil)