Handle ActionDispatch unrecognized routes

Author: Strech

lib/datadog/appsec/api_security/route_extractor.rb

@@ -49,6 +49,9 @@ def self.route_pattern(request)
             pattern = request.env[RAILS_ROUTES_KEY].router
               .recognize(request) { |route, _| break route.path.spec.to_s }
 
+            # NOTE: If rails is unable to recognize request it returns empty Array
+            pattern = nil if pattern&.empty?
+
             # NOTE: If rails can't recognize the request, we are going to fallback
             #       to generic request path
             (pattern || request.path).delete_suffix(RAILS_FORMAT_SUFFIX)

spec/datadog/appsec/api_security/route_extractor_spec.rb

@@ -91,6 +91,19 @@
 
         it { expect(described_class.route_pattern(request)).to eq('/api/v1/users/:id/posts/:post_id') }
       end
+
+      context 'when Rails router cannot recognize request' do
+        before do
+          allow(request).to receive(:env).and_return({'action_dispatch.routes' => route_set})
+          allow(request).to receive(:path).and_return('/unmatched/route')
+          allow(router).to receive(:recognize).with(request).and_return([])
+        end
+
+        let(:router) { double('ActionDispatch::Routing::RouteSet::Router') }
+        let(:route_set) { double('ActionDispatch::Routing::RouteSet', router: router) }
+
+        it { expect(described_class.route_pattern(request)).to eq('/unmatched/route') }
+      end
     end
 
     context 'when Rack routing is present' do