From ffb107ac7d8ba17ecd4d10ef1d8a94d5c62630b2 Mon Sep 17 00:00:00 2001
From: Oswaldo Ferreira <oswaldo@gitlab.com>
Date: Mon, 26 Feb 2018 12:28:49 -0300
Subject: [PATCH] Keep link when redacting unauthorized object links

---
 ...nk-when-redacting-unauthorized-objects.yml |  5 ++++
 .../filter/abstract_reference_filter.rb       | 15 ++++++-----
 lib/banzai/redactor.rb                        | 25 ++++++++++++++++---
 spec/lib/banzai/redactor_spec.rb              | 10 ++++++++
 4 files changed, 45 insertions(+), 10 deletions(-)
 create mode 100644 changelogs/unreleased/40502-osw-keep-link-when-redacting-unauthorized-objects.yml

diff --git a/changelogs/unreleased/40502-osw-keep-link-when-redacting-unauthorized-objects.yml b/changelogs/unreleased/40502-osw-keep-link-when-redacting-unauthorized-objects.yml
new file mode 100644
index 00000000000..dddd8473df5
--- /dev/null
+++ b/changelogs/unreleased/40502-osw-keep-link-when-redacting-unauthorized-objects.yml
@@ -0,0 +1,5 @@
+---
+title: Keep link when redacting unauthorized object links
+merge_request:
+author:
+type: fixed
diff --git a/lib/banzai/filter/abstract_reference_filter.rb b/lib/banzai/filter/abstract_reference_filter.rb
index e7e6a90b5fd..c9e3f8ce42b 100644
--- a/lib/banzai/filter/abstract_reference_filter.rb
+++ b/lib/banzai/filter/abstract_reference_filter.rb
@@ -174,7 +174,9 @@ module Banzai
             title = object_link_title(object)
             klass = reference_class(object_sym)
 
-            data = data_attributes_for(link_content || match, parent, object, link: !!link_content)
+            data = data_attributes_for(link_content || match, parent, object,
+                                       link_content: !!link_content,
+                                       link_reference: link_reference)
 
             url =
               if matches.names.include?("url") && matches[:url]
@@ -194,12 +196,13 @@ module Banzai
         end
       end
 
-      def data_attributes_for(text, project, object, link: false)
+      def data_attributes_for(text, project, object, link_content: false, link_reference: false)
         data_attribute(
-          original:     text,
-          link:         link,
-          project:      project.id,
-          object_sym => object.id
+          original:       text,
+          link:           link_content,
+          link_reference: link_reference,
+          project:        project.id,
+          object_sym =>   object.id
         )
       end
 
diff --git a/lib/banzai/redactor.rb b/lib/banzai/redactor.rb
index 827df7c08ae..fd457bebf03 100644
--- a/lib/banzai/redactor.rb
+++ b/lib/banzai/redactor.rb
@@ -42,16 +42,33 @@ module Banzai
           next if visible.include?(node)
 
           doc_data[:visible_reference_count] -= 1
-          # The reference should be replaced by the original link's content,
-          # which is not always the same as the rendered one.
-          content = node.attr('data-original') || node.inner_html
-          node.replace(content)
+          redacted_content = redacted_node_content(node)
+          node.replace(redacted_content)
         end
       end
 
       metadata
     end
 
+    # Return redacted content of given node as either the original link (<a> tag),
+    # the original content (text), or the inner HTML of the node.
+    #
+    def redacted_node_content(node)
+      original_content = node.attr('data-original')
+      link_reference = node.attr('data-link-reference')
+
+      # Build the raw <a> tag just with a link as href and content if
+      # it's originally a link pattern. We shouldn't return a plain text href.
+      original_link =
+        if link_reference == 'true' && href = original_content
+          %(<a href="#{href}">#{href}</a>)
+        end
+
+      # The reference should be replaced by the original link's content,
+      # which is not always the same as the rendered one.
+      original_link || original_content || node.inner_html
+    end
+
     def redact_cross_project_references(documents)
       extractor = Banzai::IssuableExtractor.new(project, user)
       issuables = extractor.extract(documents)
diff --git a/spec/lib/banzai/redactor_spec.rb b/spec/lib/banzai/redactor_spec.rb
index 1fa89137972..441f3725985 100644
--- a/spec/lib/banzai/redactor_spec.rb
+++ b/spec/lib/banzai/redactor_spec.rb
@@ -40,6 +40,16 @@ describe Banzai::Redactor do
           expect(doc.to_html).to eq(original_content)
         end
       end
+
+      it 'returns <a> tag with original href if it is originally a link reference' do
+        href = 'http://localhost:3000'
+        doc = Nokogiri::HTML
+          .fragment("<a class='gfm' data-reference-type='issue' data-original=#{href} data-link-reference='true'>#{href}</a>")
+
+        redactor.redact([doc])
+
+        expect(doc.to_html).to eq('<a href="http://localhost:3000">http://localhost:3000</a>')
+      end
     end
 
     context 'when project is in pending delete' do