Add size limit for link preview URLs (mastodon#30854)

AgathaSorceress · Dec 22, 2024 · 4679f79 · 4679f79
1 parent 3cfb504
commit 4679f79
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diff --git a/app/services/fetch_link_card_service.rb b/app/services/fetch_link_card_service.rb
@@ -15,6 +15,9 @@ class FetchLinkCardService < BaseService
     )
   }iox
 
+  # URL size limit to safely store in PosgreSQL's unique indexes
+  BYTESIZE_LIMIT = 2692
+
   def call(status)
     @status       = status
     @original_url = parse_urls
@@ -85,7 +88,7 @@ def parse_urls
 
   def bad_url?(uri)
     # Avoid local instance URLs and invalid URLs
-    uri.host.blank? || TagManager.instance.local_url?(uri.to_s) || !%w(http https).include?(uri.scheme)
+    uri.host.blank? || TagManager.instance.local_url?(uri.to_s) || !%w(http https).include?(uri.scheme) || uri.to_s.bytesize > BYTESIZE_LIMIT
   end
 
   def mention_link?(anchor)

diff --git a/spec/services/fetch_link_card_service_spec.rb b/spec/services/fetch_link_card_service_spec.rb
@@ -193,6 +193,19 @@
       end
     end
 
+    context 'with an URL too long for PostgreSQL unique indexes' do
+      let(:url) { "http://example.com/#{'a' * 2674}" }
+      let(:status) { Fabricate(:status, text: url) }
+
+      it 'does not fetch the URL' do
+        expect(a_request(:get, url)).to_not have_been_made
+      end
+
+      it 'does not create a preview card' do
+        expect(status.preview_card).to be_nil
+      end
+    end
+
     context 'with a URL of a page with oEmbed support' do
       let(:html) { '<!doctype html><title>Hello world</title><link rel="alternate" type="application/json+oembed" href="http://example.com/oembed?url=http://example.com/html">' }
       let(:status) { Fabricate(:status, text: 'http://example.com/html') }