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Fix some link previews being incorrectly generated from other prior links (#16885)

* Add tests

* Fix some link previews being incorrectly generated from different prior links

PR #12403 added a cache to avoid redundant queries when the OEmbed endpoint can
be guessed from the URL. This caching mechanism is not perfectly correct as
there is no guarantee that all pages from a given domain share the same
OEmbed provider endpoint.

This PR prevents the FetchOEmbedService from caching OEmbed endpoint that
cannot be generalized by replacing a fully-qualified URL from the endpoint's
parameters, greatly reducing the number of incorrect cached generalizations.
Claire 2 years ago
parent
e63370db19
commit
123a88b6b5
3 changed files with 52 additions and 1 deletions
Split View Show Diff Stats
  1. 4 1
      app/services/fetch_oembed_service.rb
  2. 7 0
      spec/fixtures/requests/oembed_youtube.html
  3. 41 0
      spec/services/fetch_oembed_service_spec.rb

+ 4 - 1
app/services/fetch_oembed_service.rb
View File 

@@ -2,6 +2,7 @@
 
 
 class FetchOEmbedService
 
   ENDPOINT_CACHE_EXPIRES_IN = 24.hours.freeze
 
+  URL_REGEX                 = /(=(http[s]?(%3A|:)(\/\/|%2F%2F)))([^&]*)/i.freeze
 
 
   attr_reader :url, :options, :format, :endpoint_url
 
 
@@ -65,10 +66,12 @@ class FetchOEmbedService
 
   end
 
 
   def cache_endpoint!
 
+    return unless URL_REGEX.match?(@endpoint_url)
 
+
 
     url_domain = Addressable::URI.parse(@url).normalized_host
 
 
     endpoint_hash = {
 
-      endpoint: @endpoint_url.gsub(/(=(http[s]?(%3A|:)(\/\/|%2F%2F)))([^&]*)/i, '={url}'),
 
+      endpoint: @endpoint_url.gsub(URL_REGEX, '={url}'),
 
       format: @format,
 
     }

+ 7 - 0
spec/fixtures/requests/oembed_youtube.html
View File 

@@ -0,0 +1,7 @@
 
+<!DOCTYPE html>
 
+<html>
 
+  <head>
 
+    <link rel="alternate" type="application/json+oembed" href="https://www.youtube.com/oembed?format=json&amp;url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DIPSbNdBmWKE" title="What is Mastodon?">
 
+  </head>
 
+  <body></body>
 
+</html>

+ 41 - 0
spec/services/fetch_oembed_service_spec.rb
View File 

@@ -13,6 +13,32 @@ describe FetchOEmbedService, type: :service do
 
 
   describe 'discover_provider' do
 
     context 'when status code is 200 and MIME type is text/html' do
 
+      context 'when OEmbed endpoint contains URL as parameter' do
 
+        before do
 
+          stub_request(:get, 'https://www.youtube.com/watch?v=IPSbNdBmWKE').to_return(
 
+            status: 200,
 
+            headers: { 'Content-Type': 'text/html' },
 
+            body: request_fixture('oembed_youtube.html'),
 
+          )
 
+          stub_request(:get, 'https://www.youtube.com/oembed?format=json&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DIPSbNdBmWKE').to_return(
 
+            status: 200,
 
+            headers: { 'Content-Type': 'text/html' },
 
+            body: request_fixture('oembed_json_empty.html')
 
+          )
 
+        end
 
+
 
+        it 'returns new OEmbed::Provider for JSON provider' do
 
+          subject.call('https://www.youtube.com/watch?v=IPSbNdBmWKE')
 
+          expect(subject.endpoint_url).to eq 'https://www.youtube.com/oembed?format=json&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DIPSbNdBmWKE'
 
+          expect(subject.format).to eq :json
 
+        end
 
+
 
+        it 'stores URL template' do
 
+          subject.call('https://www.youtube.com/watch?v=IPSbNdBmWKE')
 
+          expect(Rails.cache.read('oembed_endpoint:www.youtube.com')[:endpoint]).to eq 'https://www.youtube.com/oembed?format=json&url={url}'
 
+        end
 
+      end
 
+
 
       context 'Both of JSON and XML provider are discoverable' do
 
         before do
 
           stub_request(:get, 'https://host.test/oembed.html').to_return(
 
@@ -33,6 +59,11 @@ describe FetchOEmbedService, type: :service do
 
           expect(subject.endpoint_url).to eq 'https://host.test/provider.xml'
 
           expect(subject.format).to eq :xml
 
         end
 
+
 
+        it 'does not cache OEmbed endpoint' do
 
+          subject.call('https://host.test/oembed.html', format: :xml)
 
+          expect(Rails.cache.exist?('oembed_endpoint:host.test')).to eq false
 
+        end
 
       end
 
 
       context 'JSON provider is discoverable while XML provider is not' do
 
@@ -49,6 +80,11 @@ describe FetchOEmbedService, type: :service do
 
           expect(subject.endpoint_url).to eq 'https://host.test/provider.json'
 
           expect(subject.format).to eq :json
 
         end
 
+
 
+        it 'does not cache OEmbed endpoint' do
 
+          subject.call('https://host.test/oembed.html')
 
+          expect(Rails.cache.exist?('oembed_endpoint:host.test')).to eq false
 
+        end
 
       end
 
 
       context 'XML provider is discoverable while JSON provider is not' do
 
@@ -65,6 +101,11 @@ describe FetchOEmbedService, type: :service do
 
           expect(subject.endpoint_url).to eq 'https://host.test/provider.xml'
 
           expect(subject.format).to eq :xml
 
         end
 
+
 
+        it 'does not cache OEmbed endpoint' do
 
+          subject.call('https://host.test/oembed.html')
 
+          expect(Rails.cache.exist?('oembed_endpoint:host.test')).to eq false
 
+        end
 
       end
 
 
       context 'Invalid XML provider is discoverable while JSON provider is not' do