Add tests

synapse/federation/federation_client.py

@@ -358,8 +358,13 @@ async def get_pdu(
             The requested PDU, or None if we were unable to find it.
         """
 
+        logger.debug(
+            "get_pdu: event_id=%s from destinations=%s", event_id, destinations
+        )
+
         # TODO: Rate limit the number of times we try and get the same event.
 
+        event_copy = None
         event_from_cache = self._get_pdu_cache.get(event_id)
         if event_from_cache:
             assert not event_from_cache.internal_metadata.outlier, (
@@ -378,6 +383,7 @@ async def get_pdu(
                 internal_metadata_dict=None,
             )
 
+            logger.debug("get_pdu: returning event_from_cache=%s", event_from_cache)
             return event_copy
 
         pdu_attempts = self.pdu_destination_tried.setdefault(event_id, {})
@@ -387,6 +393,13 @@ async def get_pdu(
             now = self._clock.time_msec()
             last_attempt = pdu_attempts.get(destination, 0)
             if last_attempt + PDU_RETRY_TIME_MS > now:
+                logger.debug(
+                    "get_pdu: skipping destination=%s because we tried it recently last_attempt=%s and we only check every %s (now=%s)",
+                    destination,
+                    last_attempt,
+                    PDU_RETRY_TIME_MS,
+                    now,
+                )
                 continue
 
             try:

tests/federation/test_federation_client.py

@@ -22,6 +22,7 @@
 from twisted.test.proto_helpers import MemoryReactor
 
 from synapse.api.room_versions import RoomVersions
+from synapse.events import EventBase
 from synapse.server import HomeServer
 from synapse.types import JsonDict
 from synapse.util import Clock
@@ -38,31 +39,35 @@ def prepare(self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer):
         self._mock_agent = mock.create_autospec(twisted.web.client.Agent, spec_set=True)
         homeserver.get_federation_http_client().agent = self._mock_agent
 
-    def test_get_room_state(self):
-        creator = f"@creator:{self.OTHER_SERVER_NAME}"
-        test_room_id = "!room_id"
+        # Move clock up to somewhat realistic time so the PDU destination retry
+        # works (`now` needs to be larger than `0 + PDU_RETRY_TIME_MS`).
+        self.reactor.advance(1000000000)
+
+        self.creator = f"@creator:{self.OTHER_SERVER_NAME}"
+        self.test_room_id = "!room_id"
 
+    def test_get_room_state(self):
         # mock up some events to use in the response.
         # In real life, these would have things in `prev_events` and `auth_events`, but that's
         # a bit annoying to mock up, and the code under test doesn't care, so we don't bother.
         create_event_dict = self.add_hashes_and_signatures_from_other_server(
             {
-                "room_id": test_room_id,
+                "room_id": self.test_room_id,
                 "type": "m.room.create",
                 "state_key": "",
-                "sender": creator,
-                "content": {"creator": creator},
+                "sender": self.creator,
+                "content": {"creator": self.creator},
                 "prev_events": [],
                 "auth_events": [],
                 "origin_server_ts": 500,
             }
         )
         member_event_dict = self.add_hashes_and_signatures_from_other_server(
             {
-                "room_id": test_room_id,
+                "room_id": self.test_room_id,
                 "type": "m.room.member",
-                "sender": creator,
-                "state_key": creator,
+                "sender": self.creator,
+                "state_key": self.creator,
                 "content": {"membership": "join"},
                 "prev_events": [],
                 "auth_events": [],
@@ -71,9 +76,9 @@ def test_get_room_state(self):
         )
         pl_event_dict = self.add_hashes_and_signatures_from_other_server(
             {
-                "room_id": test_room_id,
+                "room_id": self.test_room_id,
                 "type": "m.room.power_levels",
-                "sender": creator,
+                "sender": self.creator,
                 "state_key": "",
                 "content": {},
                 "prev_events": [],
@@ -103,7 +108,7 @@ def test_get_room_state(self):
         state_resp, auth_resp = self.get_success(
             self.hs.get_federation_client().get_room_state(
                 "yet_another_server",
-                test_room_id,
+                self.test_room_id,
                 "event_id",
                 RoomVersions.V9,
             )
@@ -130,6 +135,99 @@ def test_get_room_state(self):
             ["m.room.create", "m.room.member", "m.room.power_levels"],
         )
 
+    def test_get_pdu_returns_nothing_when_event_does_not_exist(self):
+        """No event should be returned when there the event does not exist"""
+        remote_pdu = self.get_success(
+            self.hs.get_federation_client().get_pdu(
+                ["yet_another_server"],
+                "event_should_not_exist",
+                RoomVersions.V9,
+            )
+        )
+        self.assertEqual(remote_pdu, None)
+
+    def test_get_pdu(self):
+        """Test to make sure an event is returned by `get_pdu()`"""
+        self._get_pdu_once()
+
+    def test_get_pdu_event_from_cache_is_pristine(self):
+        """Test that modifications made to events returned by `get_pdu()`
+        do not propagate back to to the internal cache (events returned should
+        be a copy).
+        """
+
+        # Get the PDU in the cache
+        remote_pdu = self._get_pdu_once()
+
+        # Modify the the event reference.
+        # This change should not make it back to the `_get_pdu_cache`.
+        remote_pdu.internal_metadata.outlier = True
+
+        # Get the event again
+        remote_pdu2 = self.get_success(
+            self.hs.get_federation_client().get_pdu(
+                ["yet_another_server"],
+                remote_pdu.event_id,
+                RoomVersions.V9,
+            )
+        )
+
+        # Make sure event does not include modification earlier
+        self.assertIsNotNone(remote_pdu2)
+        self.assertEqual(remote_pdu2.internal_metadata.outlier, False)
+
+    def _get_pdu_once(self) -> EventBase:
+        """Retrieve an event via `get_pdu()` and asserts that an event was returned.
+        Also used to prime the cache for subsequent test logic.
+        """
+        message_event_dict = self.add_hashes_and_signatures_from_other_server(
+            {
+                "room_id": "!room_id",
+                "type": "m.room.message",
+                "sender": self.creator,
+                "state_key": "",
+                "content": {},
+                "prev_events": [],
+                "auth_events": [],
+                "origin_server_ts": 700,
+                "depth": 10,
+            }
+        )
+
+        # mock up the response, and have the agent return it
+        self._mock_agent.request.side_effect = lambda *args, **kwargs: defer.succeed(
+            _mock_response(
+                {
+                    "origin": "yet_another_server",
+                    "origin_server_ts": 900,
+                    "pdus": [
+                        message_event_dict,
+                    ],
+                }
+            )
+        )
+
+        remote_pdu = self.get_success(
+            self.hs.get_federation_client().get_pdu(
+                ["yet_another_server"],
+                "event_id",
+                RoomVersions.V9,
+            )
+        )
+
+        # check the right call got made to the agent
+        self._mock_agent.request.assert_called_once_with(
+            b"GET",
+            b"matrix://yet_another_server/_matrix/federation/v1/event/event_id",
+            headers=mock.ANY,
+            bodyProducer=None,
+        )
+
+        self.assertIsNotNone(remote_pdu)
+        self.assertEqual(remote_pdu.internal_metadata.outlier, False)
+
+        return remote_pdu
+
 
 def _mock_response(resp: JsonDict):
     body = json.dumps(resp).encode("utf-8")