Move methods involving event authentication to EventAuthHandler. (#10268)

Instead of mixing them with user authentication methods.

5 files changed, 95 insertions, 21 deletions

diff --git a/synapse/handlers/event_auth.py b/synapse/handlers/event_auth.py
index 989996b628..41dbdfd0a1 100644
--- a/synapse/handlers/event_auth.py
+++ b/synapse/handlers/event_auth.py
@@ -11,8 +11,9 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from typing import TYPE_CHECKING, Collection, Optional
+from typing import TYPE_CHECKING, Collection, List, Optional, Union
 
+from synapse import event_auth
 from synapse.api.constants import (
     EventTypes,
     JoinRules,
@@ -20,9 +21,11 @@ from synapse.api.constants import (
     RestrictedJoinRuleTypes,
 )
 from synapse.api.errors import AuthError
-from synapse.api.room_versions import RoomVersion
+from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, RoomVersion
 from synapse.events import EventBase
+from synapse.events.builder import EventBuilder
 from synapse.types import StateMap
+from synapse.util.metrics import Measure
 
 if TYPE_CHECKING:
     from synapse.server import HomeServer
@@ -34,8 +37,63 @@ class EventAuthHandler:
     """
 
     def __init__(self, hs: "HomeServer"):
+        self._clock = hs.get_clock()
         self._store = hs.get_datastore()
 
+    async def check_from_context(
+        self, room_version: str, event, context, do_sig_check=True
+    ) -> None:
+        auth_event_ids = event.auth_event_ids()
+        auth_events_by_id = await self._store.get_events(auth_event_ids)
+        auth_events = {(e.type, e.state_key): e for e in auth_events_by_id.values()}
+
+        room_version_obj = KNOWN_ROOM_VERSIONS[room_version]
+        event_auth.check(
+            room_version_obj, event, auth_events=auth_events, do_sig_check=do_sig_check
+        )
+
+    def compute_auth_events(
+        self,
+        event: Union[EventBase, EventBuilder],
+        current_state_ids: StateMap[str],
+        for_verification: bool = False,
+    ) -> List[str]:
+        """Given an event and current state return the list of event IDs used
+        to auth an event.
+
+        If `for_verification` is False then only return auth events that
+        should be added to the event's `auth_events`.
+
+        Returns:
+            List of event IDs.
+        """
+
+        if event.type == EventTypes.Create:
+            return []
+
+        # Currently we ignore the `for_verification` flag even though there are
+        # some situations where we can drop particular auth events when adding
+        # to the event's `auth_events` (e.g. joins pointing to previous joins
+        # when room is publicly joinable). Dropping event IDs has the
+        # advantage that the auth chain for the room grows slower, but we use
+        # the auth chain in state resolution v2 to order events, which means
+        # care must be taken if dropping events to ensure that it doesn't
+        # introduce undesirable "state reset" behaviour.
+        #
+        # All of which sounds a bit tricky so we don't bother for now.
+
+        auth_ids = []
+        for etype, state_key in event_auth.auth_types_for_event(event):
+            auth_ev_id = current_state_ids.get((etype, state_key))
+            if auth_ev_id:
+                auth_ids.append(auth_ev_id)
+
+        return auth_ids
+
+    async def check_host_in_room(self, room_id: str, host: str) -> bool:
+        with Measure(self._clock, "check_host_in_room"):
+            return await self._store.is_host_joined(room_id, host)
+
     async def check_restricted_join_rules(
         self,
         state_ids: StateMap[str],
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index d929c65131..991ec9919a 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -250,7 +250,9 @@ class FederationHandler(BaseHandler):
         #
         # Note that if we were never in the room then we would have already
         # dropped the event, since we wouldn't know the room version.
-        is_in_room = await self.auth.check_host_in_room(room_id, self.server_name)
+        is_in_room = await self._event_auth_handler.check_host_in_room(
+            room_id, self.server_name
+        )
         if not is_in_room:
             logger.info(
                 "Ignoring PDU from %s as we're not in the room",
@@ -1674,7 +1676,9 @@ class FederationHandler(BaseHandler):
         room_version = await self.store.get_room_version_id(room_id)
 
         # now check that we are *still* in the room
-        is_in_room = await self.auth.check_host_in_room(room_id, self.server_name)
+        is_in_room = await self._event_auth_handler.check_host_in_room(
+            room_id, self.server_name
+        )
         if not is_in_room:
             logger.info(
                 "Got /make_join request for room %s we are no longer in",
@@ -1705,7 +1709,7 @@ class FederationHandler(BaseHandler):
 
         # The remote hasn't signed it yet, obviously. We'll do the full checks
         # when we get the event back in `on_send_join_request`
-        await self.auth.check_from_context(
+        await self._event_auth_handler.check_from_context(
             room_version, event, context, do_sig_check=False
         )
 
@@ -1877,7 +1881,7 @@ class FederationHandler(BaseHandler):
         try:
             # The remote hasn't signed it yet, obviously. We'll do the full checks
             # when we get the event back in `on_send_leave_request`
-            await self.auth.check_from_context(
+            await self._event_auth_handler.check_from_context(
                 room_version, event, context, do_sig_check=False
             )
         except AuthError as e:
@@ -1939,7 +1943,7 @@ class FederationHandler(BaseHandler):
         try:
             # The remote hasn't signed it yet, obviously. We'll do the full checks
             # when we get the event back in `on_send_knock_request`
-            await self.auth.check_from_context(
+            await self._event_auth_handler.check_from_context(
                 room_version, event, context, do_sig_check=False
             )
         except AuthError as e:
@@ -2111,7 +2115,7 @@ class FederationHandler(BaseHandler):
     async def on_backfill_request(
         self, origin: str, room_id: str, pdu_list: List[str], limit: int
     ) -> List[EventBase]:
-        in_room = await self.auth.check_host_in_room(room_id, origin)
+        in_room = await self._event_auth_handler.check_host_in_room(room_id, origin)
         if not in_room:
             raise AuthError(403, "Host not in room.")
 
@@ -2146,7 +2150,9 @@ class FederationHandler(BaseHandler):
         )
 
         if event:
-            in_room = await self.auth.check_host_in_room(event.room_id, origin)
+            in_room = await self._event_auth_handler.check_host_in_room(
+                event.room_id, origin
+            )
             if not in_room:
                 raise AuthError(403, "Host not in room.")
 
@@ -2499,7 +2505,7 @@ class FederationHandler(BaseHandler):
         latest_events: List[str],
         limit: int,
     ) -> List[EventBase]:
-        in_room = await self.auth.check_host_in_room(room_id, origin)
+        in_room = await self._event_auth_handler.check_host_in_room(room_id, origin)
         if not in_room:
             raise AuthError(403, "Host not in room.")
 
@@ -2562,7 +2568,7 @@ class FederationHandler(BaseHandler):
 
         if not auth_events:
             prev_state_ids = await context.get_prev_state_ids()
-            auth_events_ids = self.auth.compute_auth_events(
+            auth_events_ids = self._event_auth_handler.compute_auth_events(
                 event, prev_state_ids, for_verification=True
             )
             auth_events_x = await self.store.get_events(auth_events_ids)
@@ -2991,7 +2997,7 @@ class FederationHandler(BaseHandler):
             "state_key": target_user_id,
         }
 
-        if await self.auth.check_host_in_room(room_id, self.hs.hostname):
+        if await self._event_auth_handler.check_host_in_room(room_id, self.hs.hostname):
             room_version = await self.store.get_room_version_id(room_id)
             builder = self.event_builder_factory.new(room_version, event_dict)
 
@@ -3011,7 +3017,9 @@ class FederationHandler(BaseHandler):
             event.internal_metadata.send_on_behalf_of = self.hs.hostname
 
             try:
-                await self.auth.check_from_context(room_version, event, context)
+                await self._event_auth_handler.check_from_context(
+                    room_version, event, context
+                )
             except AuthError as e:
                 logger.warning("Denying new third party invite %r because %s", event, e)
                 raise e
@@ -3054,7 +3062,9 @@ class FederationHandler(BaseHandler):
         )
 
         try:
-            await self.auth.check_from_context(room_version, event, context)
+            await self._event_auth_handler.check_from_context(
+                room_version, event, context
+            )
         except AuthError as e:
             logger.warning("Denying third party invite %r because %s", event, e)
             raise e
@@ -3142,7 +3152,7 @@ class FederationHandler(BaseHandler):
         last_exception = None  # type: Optional[Exception]
 
         # for each public key in the 3pid invite event
-        for public_key_object in self.hs.get_auth().get_public_keys(invite_event):
+        for public_key_object in event_auth.get_public_keys(invite_event):
             try:
                 # for each sig on the third_party_invite block of the actual invite
                 for server, signature_block in signed["signatures"].items():
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 364c5cd2d3..66e40a915d 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -385,6 +385,7 @@ class EventCreationHandler:
     def __init__(self, hs: "HomeServer"):
         self.hs = hs
         self.auth = hs.get_auth()
+        self._event_auth_handler = hs.get_event_auth_handler()
         self.store = hs.get_datastore()
         self.storage = hs.get_storage()
         self.state = hs.get_state_handler()
@@ -597,7 +598,7 @@ class EventCreationHandler:
                 (e.type, e.state_key): e.event_id for e in auth_events
             }
             # Actually strip down and use the necessary auth events
-            auth_event_ids = self.auth.compute_auth_events(
+            auth_event_ids = self._event_auth_handler.compute_auth_events(
                 event=temp_event,
                 current_state_ids=auth_event_state_map,
                 for_verification=False,
@@ -1056,7 +1057,9 @@ class EventCreationHandler:
             assert event.content["membership"] == Membership.LEAVE
         else:
             try:
-                await self.auth.check_from_context(room_version, event, context)
+                await self._event_auth_handler.check_from_context(
+                    room_version, event, context
+                )
             except AuthError as err:
                 logger.warning("Denying new event %r because %s", event, err)
                 raise err
@@ -1381,7 +1384,7 @@ class EventCreationHandler:
                     raise AuthError(403, "Redacting server ACL events is not permitted")
 
             prev_state_ids = await context.get_prev_state_ids()
-            auth_events_ids = self.auth.compute_auth_events(
+            auth_events_ids = self._event_auth_handler.compute_auth_events(
                 event, prev_state_ids, for_verification=True
             )
             auth_events_map = await self.store.get_events(auth_events_ids)
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 835d874cee..579b1b93c5 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -83,6 +83,7 @@ class RoomCreationHandler(BaseHandler):
         self.spam_checker = hs.get_spam_checker()
         self.event_creation_handler = hs.get_event_creation_handler()
         self.room_member_handler = hs.get_room_member_handler()
+        self._event_auth_handler = hs.get_event_auth_handler()
         self.config = hs.config
 
         # Room state based off defined presets
@@ -226,7 +227,7 @@ class RoomCreationHandler(BaseHandler):
             },
         )
         old_room_version = await self.store.get_room_version_id(old_room_id)
-        await self.auth.check_from_context(
+        await self._event_auth_handler.check_from_context(
             old_room_version, tombstone_event, tombstone_context
         )
 
diff --git a/synapse/handlers/space_summary.py b/synapse/handlers/space_summary.py
index 266f369883..b585057ec3 100644
--- a/synapse/handlers/space_summary.py
+++ b/synapse/handlers/space_summary.py
@@ -472,7 +472,7 @@ class SpaceSummaryHandler:
         # If this is a request over federation, check if the host is in the room or
         # is in one of the spaces specified via the join rules.
         elif origin:
-            if await self._auth.check_host_in_room(room_id, origin):
+            if await self._event_auth_handler.check_host_in_room(room_id, origin):
                 return True
 
             # Alternately, if the host has a user in any of the spaces specified
@@ -485,7 +485,9 @@ class SpaceSummaryHandler:
                     await self._event_auth_handler.get_rooms_that_allow_join(state_ids)
                 )
                 for space_id in allowed_rooms:
-                    if await self._auth.check_host_in_room(space_id, origin):
+                    if await self._event_auth_handler.check_host_in_room(
+                        space_id, origin
+                    ):
                         return True
 
         # otherwise, check if the room is peekable