Catch encoding errors when creating link previews. (#30853)

app/services/fetch_link_card_service.rb

@@ -32,7 +32,7 @@ class FetchLinkCardService < BaseService
     end
 
     attach_card if @card&.persisted?
-  rescue HTTP::Error, OpenSSL::SSL::SSLError, Addressable::URI::InvalidURIError, Mastodon::HostValidationError, Mastodon::LengthValidationError => e
+  rescue HTTP::Error, OpenSSL::SSL::SSLError, Addressable::URI::InvalidURIError, Mastodon::HostValidationError, Mastodon::LengthValidationError, Encoding::UndefinedConversionError => e
     Rails.logger.debug { "Error fetching link #{@original_url}: #{e}" }
     nil
   end

spec/fixtures/requests/redirect_with_utf8_url.txt

@@ -0,0 +1,5 @@
+HTTP/1.1 301 Moved Permanently
+server: nginx
+date: Thu, 27 Jun 2024 11:04:53 GMT
+content-type: text/html; charset=UTF-8
+location: http://example.com/ärgerliche-umlaute.html

spec/services/fetch_link_card_service_spec.rb

@@ -27,6 +27,7 @@ RSpec.describe FetchLinkCardService do
     stub_request(:get, 'http://example.com/koi8-r').to_return(request_fixture('koi8-r.txt'))
     stub_request(:get, 'http://example.com/windows-1251').to_return(request_fixture('windows-1251.txt'))
     stub_request(:get, 'http://example.com/low_confidence_latin1').to_return(request_fixture('low_confidence_latin1.txt'))
+    stub_request(:get, 'http://example.com/aergerliche-umlaute').to_return(request_fixture('redirect_with_utf8_url.txt'))
 
     Rails.cache.write('oembed_endpoint:example.com', oembed_cache) if oembed_cache
 
@@ -101,6 +102,14 @@ RSpec.describe FetchLinkCardService do
       end
     end
 
+    context 'with a redirect URL with faulty encoding' do
+      let(:status) { Fabricate(:status, text: 'http://example.com/aergerliche-umlaute') }
+
+      it 'does not create a preview card' do
+        expect(status.preview_card).to be_nil
+      end
+    end
+
     context 'with a 404 URL' do
       let(:status) { Fabricate(:status, text: 'http://example.com/not-found') }