Add variant of TestNewUserCannotGetKeysForOfflineServer where B,C alr…

…eady share an E2EE room

tests/federation_connectivity_test.go

@@ -110,3 +110,107 @@ func TestNewUserCannotGetKeysForOfflineServer(t *testing.T) {
 	ev := bob.MustGetEvent(t, roomID, undecryptableEventID)
 	must.Equal(t, ev.FailedToDecrypt, true, "bob was able to decrypt the undecryptable event")
 }
+
+// A and B are in a room, on different servers.
+// C and B are in another room, on different servers.
+// B's server goes offline.
+// C joins the room (on A's server).
+// C sends a message. C will not be able to get device keys for B, but should already have them from previous room.
+// B comes back online.
+// B will be able to decrypt C's message.
+// This is ultimately checking that Olm sessions are per-device and not per-room.
+func TestExistingSessionCannotGetKeysForOfflineServer(t *testing.T) {
+	deployment := Deploy(t)
+	csapiAlice := deployment.Register(t, "hs1", helpers.RegistrationOpts{
+		LocalpartSuffix: "alice",
+		Password:        "complement-crypto-password",
+	})
+	csapiBob := deployment.Register(t, "hs2", helpers.RegistrationOpts{
+		LocalpartSuffix: "bob",
+		Password:        "complement-crypto-password",
+	})
+	csapiCharlie := deployment.Register(t, "hs1", helpers.RegistrationOpts{
+		LocalpartSuffix: "charlie",
+		Password:        "complement-crypto-password",
+	})
+	roomIDbc := csapiCharlie.MustCreateRoom(t, map[string]interface{}{
+		"preset": "private_chat",
+		"invite": []string{csapiBob.UserID},
+		"initial_state": []map[string]interface{}{
+			{
+				"type":      "m.room.encryption",
+				"state_key": "",
+				"content": map[string]interface{}{
+					"algorithm": "m.megolm.v1.aes-sha2",
+				},
+			},
+		},
+	})
+	roomIDab := csapiAlice.MustCreateRoom(t, map[string]interface{}{
+		"preset": "private_chat",
+		"invite": []string{csapiBob.UserID},
+		"initial_state": []map[string]interface{}{
+			{
+				"type":      "m.room.encryption",
+				"state_key": "",
+				"content": map[string]interface{}{
+					"algorithm": "m.megolm.v1.aes-sha2",
+				},
+			},
+		},
+	})
+	csapiBob.MustJoinRoom(t, roomIDab, []string{"hs1"})
+	csapiBob.MustJoinRoom(t, roomIDbc, []string{"hs1"})
+
+	ss := deployment.SlidingSyncURL(t)
+	alice := MustLoginClient(t, api.ClientType{HS: "hs1", Lang: api.ClientTypeRust}, api.FromComplementClient(csapiAlice, "complement-crypto-password"), ss)
+	defer alice.Close(t)
+	bob := MustLoginClient(t, api.ClientType{HS: "hs2", Lang: api.ClientTypeJS}, api.FromComplementClient(csapiBob, "complement-crypto-password"), ss)
+	defer bob.Close(t)
+	charlie := MustLoginClient(t, api.ClientType{HS: "hs1", Lang: api.ClientTypeRust}, api.FromComplementClient(csapiCharlie, "complement-crypto-password"), ss)
+	defer charlie.Close(t)
+	aliceStopSyncing := alice.StartSyncing(t)
+	defer aliceStopSyncing()
+	bobStopSyncing := bob.StartSyncing(t)
+	defer bobStopSyncing()
+	charlieStopSyncing := charlie.StartSyncing(t)
+	defer charlieStopSyncing()
+
+	// let clients sync device keys
+	time.Sleep(time.Second)
+
+	// ensure encrypted messaging works in rooms ab,bc
+	wantMsgBody := "Hello world"
+	waiter := bob.WaitUntilEventInRoom(t, roomIDab, api.CheckEventHasBody(wantMsgBody))
+	evID := alice.SendMessage(t, roomIDab, wantMsgBody)
+	t.Logf("bob (%s) waiting for event %s", bob.Type(), evID)
+	waiter.Wait(t, 5*time.Second)
+	waiter = bob.WaitUntilEventInRoom(t, roomIDbc, api.CheckEventHasBody(wantMsgBody))
+	evID = charlie.SendMessage(t, roomIDbc, wantMsgBody)
+	t.Logf("bob (%s) waiting for event %s", bob.Type(), evID)
+	waiter.Wait(t, 5*time.Second)
+
+	// now bob's HS becomes unreachable
+	deployment.PauseServer(t, "hs2")
+
+	// C now joins the room ab
+	csapiAlice.MustInviteRoom(t, roomIDab, csapiCharlie.UserID)
+	csapiCharlie.MustJoinRoom(t, roomIDab, []string{"hs1"})
+
+	// let charlie sync device keys...
+	time.Sleep(time.Second)
+
+	// send a message as C: everyone should be able to decrypt this because Olm sessions
+	// are per-device, not per-room.
+	wantDecryptableMsgBody := "Bob can see this even though his server is down as we had a session already"
+	waiter = alice.WaitUntilEventInRoom(t, roomIDab, api.CheckEventHasBody(wantDecryptableMsgBody))
+	decryptableEventID := charlie.SendMessage(t, roomIDab, wantDecryptableMsgBody)
+	t.Logf("alice (%s) waiting for event %s", alice.Type(), decryptableEventID)
+	waiter.Wait(t, 5*time.Second)
+
+	// now bob's server comes back online
+	deployment.UnpauseServer(t, "hs2")
+
+	waiter = bob.WaitUntilEventInRoom(t, roomIDab, api.CheckEventHasBody(wantDecryptableMsgBody))
+	waiter.Wait(t, 10*time.Second) // longer time to allow for retries
+}