Add test ensuring that /make_join and /send_join are rejected during …

…a partial join (#432)

internal/federation/handle.go

@@ -38,37 +38,48 @@ func MakeJoinRequestsHandler(s *Server, w http.ResponseWriter, req *http.Request
 		return
 	}
 
+	makeJoinResp, err := MakeRespMakeJoin(s, room, userID)
+	if err != nil {
+		w.WriteHeader(500)
+		w.Write([]byte(fmt.Sprintf("complement: HandleMakeSendJoinRequests %s", err)))
+		return
+	}
+
+	// Send it
+	w.WriteHeader(200)
+	b, _ := json.Marshal(makeJoinResp)
+	w.Write(b)
+}
+
+// MakeRespMakeJoin makes the response for a /make_join request, without verifying any signatures
+// or dealing with HTTP responses itself.
+func MakeRespMakeJoin(s *Server, room *ServerRoom, userID string) (resp gomatrixserverlib.RespMakeJoin, err error) {
 	// Generate a join event
 	builder := gomatrixserverlib.EventBuilder{
 		Sender:     userID,
-		RoomID:     roomID,
+		RoomID:     room.RoomID,
 		Type:       "m.room.member",
 		StateKey:   &userID,
 		PrevEvents: []string{room.Timeline[len(room.Timeline)-1].EventID()},
 		Depth:      room.Timeline[len(room.Timeline)-1].Depth() + 1,
 	}
-	err := builder.SetContent(map[string]interface{}{"membership": gomatrixserverlib.Join})
+	err = builder.SetContent(map[string]interface{}{"membership": gomatrixserverlib.Join})
 	if err != nil {
-		w.WriteHeader(500)
-		w.Write([]byte("complement: HandleMakeSendJoinRequests make_join cannot set membership content: " + err.Error()))
+		err = fmt.Errorf("make_join cannot set membership content: %w", err)
 		return
 	}
 	stateNeeded, err := gomatrixserverlib.StateNeededForEventBuilder(&builder)
 	if err != nil {
-		w.WriteHeader(500)
-		w.Write([]byte("complement: HandleMakeSendJoinRequests make_join cannot calculate auth_events: " + err.Error()))
+		err = fmt.Errorf("make_join cannot calculate auth_events: %w", err)
 		return
 	}
 	builder.AuthEvents = room.AuthEvents(stateNeeded)
 
-	// Send it
-	res := map[string]interface{}{
-		"event":        builder,
-		"room_version": room.Version,
+	resp = gomatrixserverlib.RespMakeJoin{
+		RoomVersion: room.Version,
+		JoinEvent:   builder,
 	}
-	w.WriteHeader(200)
-	b, _ := json.Marshal(res)
-	w.Write(b)
+	return
 }
 
 // SendJoinRequestsHandler is the http.Handler implementation for the send_join part of

tests/federation_room_join_partial_state_test.go

@@ -806,6 +806,125 @@ func TestPartialStateJoin(t *testing.T) {
 			},
 		)
 	})
+
+	// when the server is in the middle of a partial state join, it should not accept
+	// /make_join because it can't give a full answer.
+	t.Run("Rejects make_join during partial join", func(t *testing.T) {
+		// In this test, we have 3 homeservers:
+		//   hs1 (the server under test) with @alice:hs1
+		//     This is the server that will be in the middle of a partial join.
+		//   testServer1 (a Complement test server) with @bob:<server name>
+		//     This is the server that created the room originally.
+		//   testServer2 (another Complement test server) with @charlie:<server name>
+		//     This is the server that will try to make a join via testServer1.
+		deployment := Deploy(t, b.BlueprintAlice)
+		defer deployment.Destroy(t)
+		alice := deployment.Client(t, "hs1", "@alice:hs1")
+
+		testServer1 := createTestServer(t, deployment)
+		cancel := testServer1.Listen()
+		defer cancel()
+		serverRoom := createTestRoom(t, testServer1, alice.GetDefaultRoomVersion(t))
+		roomID := serverRoom.RoomID
+		psjResult := beginPartialStateJoin(t, testServer1, serverRoom, alice)
+		defer psjResult.Destroy()
+
+		// The partial join is now in progress.
+		// Let's have a new test server rock up and ask to join the room by making a
+		// /make_join request.
+
+		testServer2 := createTestServer(t, deployment)
+		cancel2 := testServer2.Listen()
+		defer cancel2()
+
+		fedClient2 := testServer2.FederationClient(deployment)
+
+		// charlie sends a make_join
+		_, err := fedClient2.MakeJoin(context.Background(), "hs1", roomID, testServer2.UserID("charlie"), federation.SupportedRoomVersions())
+
+		if err == nil {
+			t.Errorf("MakeJoin returned 200, want 404")
+		} else if httpError, ok := err.(gomatrix.HTTPError); ok {
+			t.Logf("MakeJoin => %d/%s", httpError.Code, string(httpError.Contents))
+			if httpError.Code != 404 {
+				t.Errorf("expected 404, got %d", httpError.Code)
+			}
+			errcode := must.GetJSONFieldStr(t, httpError.Contents, "errcode")
+			if errcode != "M_NOT_FOUND" {
+				t.Errorf("errcode: got %s, want M_NOT_FOUND", errcode)
+			}
+		} else {
+			t.Errorf("MakeJoin: non-HTTPError: %v", err)
+		}
+	})
+
+	// when the server is in the middle of a partial state join, it should not accept
+	// /send_join because it can't give a full answer.
+	t.Run("Rejects send_join during partial join", func(t *testing.T) {
+		// In this test, we have 3 homeservers:
+		//   hs1 (the server under test) with @alice:hs1
+		//     This is the server that will be in the middle of a partial join.
+		//   testServer1 (a Complement test server) with @charlie:<server name>
+		//     This is the server that will create the room originally.
+		//   testServer2 (another Complement test server) with @daniel:<server name>
+		//     This is the server that will try to join the room via hs2,
+		//     but only after using hs1 to /make_join (as otherwise we have no way
+		//     of being able to build a request to /send_join)
+		//
+		deployment := Deploy(t, b.BlueprintAlice)
+		defer deployment.Destroy(t)
+		alice := deployment.Client(t, "hs1", "@alice:hs1")
+
+		testServer1 := createTestServer(t, deployment)
+		cancel := testServer1.Listen()
+		defer cancel()
+		serverRoom := createTestRoom(t, testServer1, alice.GetDefaultRoomVersion(t))
+		psjResult := beginPartialStateJoin(t, testServer1, serverRoom, alice)
+		defer psjResult.Destroy()
+
+		// hs1's partial join is now in progress.
+		// Let's have a test server rock up and ask to /send_join in the room via hs1.
+		// To do that, we need to /make_join first.
+		// Asking hs1 to /make_join won't work, because it should reject that request.
+		// To work around that, we /make_join via hs2.
+
+		testServer2 := createTestServer(t, deployment)
+		cancel2 := testServer2.Listen()
+		defer cancel2()
+
+		fedClient2 := testServer2.FederationClient(deployment)
+
+		// Manually /make_join via testServer1.
+		// This is permissible because testServer1 is fully joined to the room.
+		// We can't actually use /make_join because host.docker.internal doesn't resolve,
+		// so compute it without making any requests:
+		makeJoinResp, err := federation.MakeRespMakeJoin(testServer1, serverRoom, testServer2.UserID("daniel"))
+		if err != nil {
+			t.Fatalf("MakeRespMakeJoin failed : %s", err)
+		}
+
+		// charlie then tries to /send_join via the homeserver under test
+		joinEvent, err := makeJoinResp.JoinEvent.Build(time.Now(), gomatrixserverlib.ServerName(testServer2.ServerName()), testServer2.KeyID, testServer2.Priv, makeJoinResp.RoomVersion)
+		must.NotError(t, "JoinEvent.Build", err)
+
+		// SendJoin should return a 404 because the homeserver under test has not
+		// finished its partial join.
+		_, err = fedClient2.SendJoin(context.Background(), "hs1", joinEvent)
+		if err == nil {
+			t.Errorf("SendJoin returned 200, want 404")
+		} else if httpError, ok := err.(gomatrix.HTTPError); ok {
+			t.Logf("SendJoin => %d/%s", httpError.Code, string(httpError.Contents))
+			if httpError.Code != 404 {
+				t.Errorf("expected 404, got %d", httpError.Code)
+			}
+			errcode := must.GetJSONFieldStr(t, httpError.Contents, "errcode")
+			if errcode != "M_NOT_FOUND" {
+				t.Errorf("errcode: got %s, want M_NOT_FOUND", errcode)
+			}
+		} else {
+			t.Errorf("SendJoin: non-HTTPError: %v", err)
+		}
+	})
 }
 
 // test reception of an event over federation during a resync