handle federation not telling us about prev_events

synapse/federation/federation_server.py

@@ -549,7 +549,9 @@ class FederationServer(FederationBase):
                 affected=pdu.event_id,
             )
 
-        yield self.handler.on_receive_pdu(origin, pdu, get_missing=True)
+        yield self.handler.on_receive_pdu(
+            origin, pdu, get_missing=True, sent_to_us_directly=True,
+        )
 
     def __str__(self):
         return "<ReplicationLayer(%s)>" % self.server_name

synapse/handlers/federation.py

@@ -44,6 +44,7 @@ from synapse.util.frozenutils import unfreeze
 from synapse.crypto.event_signing import (
     compute_event_signature, add_hashes_and_signatures,
 )
+from synapse.state import resolve_events_with_factory
 from synapse.types import UserID, get_domain_from_id
 
 from synapse.events.utils import prune_event
@@ -89,7 +90,9 @@ class FederationHandler(BaseHandler):
 
     @defer.inlineCallbacks
     @log_function
-    def on_receive_pdu(self, origin, pdu, get_missing=True):
+    def on_receive_pdu(
+            self, origin, pdu, get_missing=True, sent_to_us_directly=False,
+    ):
         """ Process a PDU received via a federation /send/ transaction, or
         via backfill of missing prev_events
 
@@ -163,7 +166,7 @@ class FederationHandler(BaseHandler):
                     "Ignoring PDU %s for room %s from %s as we've left the room!",
                     pdu.event_id, pdu.room_id, origin,
                 )
-                return
+                defer.returnValue(None)
 
         state = None
 
@@ -225,26 +228,54 @@ class FederationHandler(BaseHandler):
                         list(prevs - seen)[:5],
                     )
 
-            if prevs - seen:
-                logger.info(
-                    "Still missing %d events for room %r: %r...",
-                    len(prevs - seen), pdu.room_id, list(prevs - seen)[:5]
-                )
-                fetch_state = True
-
-        if fetch_state:
-            # We need to get the state at this event, since we haven't
-            # processed all the prev events.
-            logger.debug(
-                "_handle_new_pdu getting state for %s",
-                pdu.room_id
+            if sent_to_us_directly and prevs - seen:
+                # If they have sent it to us directly, and the server
+                # isn't telling us about the auth events that it's
+                # made a message referencing, we explode
+                raise FederationError(
+                    "ERROR",
+                    403,
+                    ("Your server isn't divulging details about prev_events "
+                     "referenced in this event."),
+                    affected=pdu.event_id,
                 )
+            elif prevs - seen:
+                # If we're walking back up the chain to fetch it, then
+                # try and find the states. If we can't get the states,
+                # discard it.
+                state_groups = []
+                auth_chains = set()
                 try:
+                    # Get the ones we know about
+                    ours = yield self.store.get_state_groups(pdu.room_id, list(seen))
+                    state_groups.append(ours)
+
+                    for p in prevs - seen:
                         state, auth_chain = yield self.replication_layer.get_state_for_room(
-                    origin, pdu.room_id, pdu.event_id,
+                            origin, pdu.room_id, p
                         )
+                        auth_chains.update(auth_chain)
+                        state_group = {
+                            (x.type, x.state_key): x.event_id for x in state
+                        }
+                        state_groups.append(state_group)
+
+                    def fetch(ev_ids):
+                        return self.store.get_events(
+                            ev_ids, get_prev_content=False, check_redacted=False,
+                        )
+
+                    state = yield resolve_events_with_factory(state_groups, {pdu.event_id: pdu}, fetch)
+
+                    state = yield self.store.get_events(state.values())
+                    state = state.values()
                 except Exception:
-                logger.exception("Failed to get state for event: %s", pdu.event_id)
+                    raise FederationError(
+                        "ERROR",
+                        403,
+                        "We can't get valid state history.",
+                        affected=pdu.event_id,
+                    )
 
         yield self._process_received_pdu(
             origin,
@@ -322,11 +353,17 @@ class FederationHandler(BaseHandler):
 
         for e in missing_events:
             logger.info("Handling found event %s", e.event_id)
+            try:
                 yield self.on_receive_pdu(
                     origin,
                     e,
                     get_missing=False
                 )
+            except FederationError as e:
+                if e.code == 403:
+                    logger.warn("Event %s failed history check.")
+                else:
+                    raise
 
     @log_function
     @defer.inlineCallbacks

tests/test_federation.py

@@ -0,0 +1,235 @@
+
+from twisted.internet.defer import Deferred, succeed, maybeDeferred
+
+from synapse.util import Clock
+from synapse.events import FrozenEvent
+from synapse.types import Requester, UserID
+from synapse.replication.slave.storage.events import SlavedEventStore
+
+from tests import unittest
+from tests.server import make_request, setup_test_homeserver, ThreadedMemoryReactorClock
+
+from mock import Mock
+
+from synapse.api.errors import CodeMessageException, HttpResponseException
+
+
+class MessageAcceptTests(unittest.TestCase):
+    def setUp(self):
+
+        self.http_client = Mock()
+        self.reactor = ThreadedMemoryReactorClock()
+        self.hs_clock = Clock(self.reactor)
+        self.homeserver = setup_test_homeserver(
+            http_client=self.http_client, clock=self.hs_clock, reactor=self.reactor
+        )
+
+        user_id = UserID("us", "test")
+        our_user = Requester(user_id, None, False, None, None)
+        room_creator = self.homeserver.get_room_creation_handler()
+        room = room_creator.create_room(
+            our_user, room_creator.PRESETS_DICT["public_chat"], ratelimit=False
+        )
+        self.reactor.advance(0.1)
+        self.room_id = self.successResultOf(room)["room_id"]
+
+        # Figure out what the most recent event is
+        most_recent = self.successResultOf(
+            self.homeserver.datastore.get_latest_event_ids_in_room(self.room_id)
+        )[0]
+
+        join_event = FrozenEvent(
+            {
+                "room_id": self.room_id,
+                "sender": "@baduser:test.serv",
+                "state_key": "@baduser:test.serv",
+                "event_id": "$join:test.serv",
+                "depth": 1000,
+                "origin_server_ts": 1,
+                "type": "m.room.member",
+                "origin": "test.servx",
+                "content": {"membership": "join"},
+                "auth_events": [],
+                "prev_state": [(most_recent, {})],
+                "prev_events": [(most_recent, {})],
+            }
+        )
+
+        self.handler = self.homeserver.get_handlers().federation_handler
+        self.handler.do_auth = lambda *a, **b: succeed(True)
+        self.client = self.homeserver.get_federation_client()
+        self.client._check_sigs_and_hash_and_fetch = lambda dest, pdus, **k: succeed(
+            pdus
+        )
+
+        # Send the join, it should return None (which is not an error)
+        d = self.handler.on_receive_pdu(
+            "test.serv", join_event, sent_to_us_directly=True
+        )
+        self.reactor.advance(1)
+        self.assertEqual(self.successResultOf(d), None)
+
+        # Make sure we actually joined the room
+        self.assertEqual(
+            self.successResultOf(
+                self.homeserver.datastore.get_latest_event_ids_in_room(self.room_id)
+            )[0],
+            "$join:test.serv",
+        )
+
+    def test_cant_hide_direct_ancestors(self):
+        """
+        If you send a message, you must be able to provide the direct
+        prev_events that said event references.
+        """
+
+        def post_json(destination, path, data, headers=None, timeout=0):
+            # If it asks us for new missing events, give them NOTHING
+            if path.startswith("/_matrix/federation/v1/get_missing_events/"):
+                return {"events": []}
+
+        self.http_client.post_json = post_json
+
+        # Figure out what the most recent event is
+        most_recent = self.successResultOf(
+            self.homeserver.datastore.get_latest_event_ids_in_room(self.room_id)
+        )[0]
+
+        # Now lie about an event
+        lying_event = FrozenEvent(
+            {
+                "room_id": self.room_id,
+                "sender": "@baduser:test.serv",
+                "event_id": "one:test.serv",
+                "depth": 1000,
+                "origin_server_ts": 1,
+                "type": "m.room.message",
+                "origin": "test.serv",
+                "content": "hewwo?",
+                "auth_events": [],
+                "prev_events": [("two:test.serv", {}), (most_recent, {})],
+            }
+        )
+
+        d = self.handler.on_receive_pdu(
+            "test.serv", lying_event, sent_to_us_directly=True
+        )
+
+        # Step the reactor, so the database fetches come back
+        self.reactor.advance(1)
+
+        # on_receive_pdu should throw an error
+        failure = self.failureResultOf(d)
+        self.assertEqual(
+            failure.value.args[0],
+            (
+                "ERROR 403: Your server isn't divulging details about prev_events "
+                "referenced in this event."
+            ),
+        )
+
+        # Make sure the invalid event isn't there
+        extrem = self.homeserver.datastore.get_latest_event_ids_in_room(self.room_id)
+        self.assertEqual(self.successResultOf(extrem)[0], "$join:test.serv")
+
+    @unittest.DEBUG
+    def test_cant_hide_past_history(self):
+        """
+        If you send a message, you must be able to provide the direct
+        prev_events that said event references.
+        """
+
+        def post_json(destination, path, data, headers=None, timeout=0):
+            if path.startswith("/_matrix/federation/v1/get_missing_events/"):
+                return {
+                    "events": [
+                        {
+                            "room_id": self.room_id,
+                            "sender": "@baduser:test.serv",
+                            "event_id": "three:test.serv",
+                            "depth": 1000,
+                            "origin_server_ts": 1,
+                            "type": "m.room.message",
+                            "origin": "test.serv",
+                            "content": "hewwo?",
+                            "auth_events": [],
+                            "prev_events": [("four:test.serv", {})],
+                        }
+                    ]
+                }
+
+        self.http_client.post_json = post_json
+
+        def get_json(destination, path, args, headers=None):
+            print(destination, path, args)
+            if path.startswith("/_matrix/federation/v1/state_ids/"):
+                d = self.successResultOf(
+                    self.homeserver.datastore.get_state_ids_for_event("one:test.serv")
+                )
+
+                return succeed(
+                    {
+                        "pdu_ids": [
+                            y
+                            for x, y in d.items()
+                            if x == ("m.room.member", "@us:test")
+                        ],
+                        "auth_chain_ids": d.values(),
+                    }
+                )
+
+        self.http_client.get_json = get_json
+
+        # Figure out what the most recent event is
+        most_recent = self.successResultOf(
+            self.homeserver.datastore.get_latest_event_ids_in_room(self.room_id)
+        )[0]
+
+        # Make a good event
+        good_event = FrozenEvent(
+            {
+                "room_id": self.room_id,
+                "sender": "@baduser:test.serv",
+                "event_id": "one:test.serv",
+                "depth": 1000,
+                "origin_server_ts": 1,
+                "type": "m.room.message",
+                "origin": "test.serv",
+                "content": "hewwo?",
+                "auth_events": [],
+                "prev_events": [(most_recent, {})],
+            }
+        )
+
+        d = self.handler.on_receive_pdu(
+            "test.serv", good_event, sent_to_us_directly=True
+        )
+        self.reactor.advance(1)
+        self.assertEqual(self.successResultOf(d), None)
+
+        bad_event = FrozenEvent(
+            {
+                "room_id": self.room_id,
+                "sender": "@baduser:test.serv",
+                "event_id": "two:test.serv",
+                "depth": 1000,
+                "origin_server_ts": 1,
+                "type": "m.room.message",
+                "origin": "test.serv",
+                "content": "hewwo?",
+                "auth_events": [],
+                "prev_events": [("one:test.serv", {}), ("three:test.serv", {})],
+            }
+        )
+
+        d = self.handler.on_receive_pdu(
+            "test.serv", bad_event, sent_to_us_directly=True
+        )
+        self.reactor.advance(1)
+
+        extrem = self.homeserver.datastore.get_latest_event_ids_in_room(self.room_id)
+        self.assertEqual(self.successResultOf(extrem)[0], "two:test.serv")
+
+        state = self.homeserver.get_state_handler().get_current_state_ids(self.room_id)
+        self.reactor.advance(1)
+        self.assertIn(("m.room.member", "@us:test"), self.successResultOf(state).keys())

tests/unittest.py

@@ -35,7 +35,7 @@ class ToTwistedHandler(logging.Handler):
     def emit(self, record):
         log_entry = self.format(record)
         log_level = record.levelname.lower().replace('warning', 'warn')
-        self.tx_log.emit(twisted.logger.LogLevel.levelWithName(log_level), log_entry)
+        self.tx_log.emit(twisted.logger.LogLevel.levelWithName(log_level), log_entry.replace("{", r"(").replace("}", r")"))
 
 
 handler = ToTwistedHandler()