Update capabilities if no hello v2 token key is found in cache.

This is necessary to detect updated Talk setups where the signaling server
might have cached capabilities without the v2 token key but the clients
are trying to connect with a hello v2 token. Fetch updated capabilities in
such cases (but throttle to about one invalidation per minute).

hub_test.go

@@ -697,7 +697,11 @@ func registerBackendHandlerUrl(t *testing.T, router *mux.Router, url string) {
 		if strings.Contains(t.Name(), "MultiRoom") {
 			signaling[ConfigKeySessionPingLimit] = 2
 		}
-		if strings.Contains(t.Name(), "V2") {
+		useV2 := true
+		if os.Getenv("SKIP_V2_CAPABILITIES") != "" {
+			useV2 = false
+		}
+		if strings.Contains(t.Name(), "V2") && useV2 {
 			key := getPublicAuthToken(t)
 			public, err := x509.MarshalPKIXPublicKey(key)
 			if err != nil {
@@ -1060,6 +1064,59 @@ func TestClientHelloV2_ExpiresAtMissing(t *testing.T) {
 	}
 }
 
+func TestClientHelloV2_CachedCapabilities(t *testing.T) {
+	for _, algo := range testHelloV2Algorithms {
+		t.Run(algo, func(t *testing.T) {
+			hub, _, _, server := CreateHubForTest(t)
+
+			ctx, cancel := context.WithTimeout(context.Background(), testTimeout)
+			defer cancel()
+
+			// Simulate old-style Nextcloud without capabilities for Hello V2.
+			t.Setenv("SKIP_V2_CAPABILITIES", "1")
+
+			client1 := NewTestClient(t, server, hub)
+			defer client1.CloseWithBye()
+
+			if err := client1.SendHelloV1(testDefaultUserId + "1"); err != nil {
+				t.Fatal(err)
+			}
+
+			hello1, err := client1.RunUntilHello(ctx)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if hello1.Hello.UserId != testDefaultUserId+"1" {
+				t.Errorf("Expected \"%s\", got %+v", testDefaultUserId+"1", hello1.Hello)
+			}
+			if hello1.Hello.SessionId == "" {
+				t.Errorf("Expected session id, got %+v", hello1.Hello)
+			}
+
+			// Simulate updated Nextcloud with capabilities for Hello V2.
+			t.Setenv("SKIP_V2_CAPABILITIES", "")
+
+			client2 := NewTestClient(t, server, hub)
+			defer client2.CloseWithBye()
+
+			if err := client2.SendHelloV2(testDefaultUserId + "2"); err != nil {
+				t.Fatal(err)
+			}
+
+			hello2, err := client2.RunUntilHello(ctx)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if hello2.Hello.UserId != testDefaultUserId+"2" {
+				t.Errorf("Expected \"%s\", got %+v", testDefaultUserId+"2", hello2.Hello)
+			}
+			if hello2.Hello.SessionId == "" {
+				t.Errorf("Expected session id, got %+v", hello2.Hello)
+			}
+		})
+	}
+}
+
 func TestClientHelloWithSpaces(t *testing.T) {
 	hub, _, _, server := CreateHubForTest(t)