Simplify `_locally_reject_invite`

Update `EventCreationHandler.create_event` to accept an auth_events param, and
use it in `_locally_reject_invite` instead of reinventing the wheel.

3 files changed, 48 insertions, 53 deletions

diff --git a/synapse/events/builder.py b/synapse/events/builder.py
index b6c47be646..df4f950fec 100644
--- a/synapse/events/builder.py
+++ b/synapse/events/builder.py
@@ -97,32 +97,37 @@ class EventBuilder:
     def is_state(self):
         return self._state_key is not None
 
-    async def build(self, prev_event_ids: List[str]) -> EventBase:
+    async def build(
+        self, prev_event_ids: List[str], auth_event_ids: Optional[List[str]]
+    ) -> EventBase:
         """Transform into a fully signed and hashed event
 
         Args:
             prev_event_ids: The event IDs to use as the prev events
+            auth_event_ids: The event IDs to use as the auth events.
+                Should normally be set to None, which will cause them to be calculated
+                based on the room state at the prev_events.
 
         Returns:
             The signed and hashed event.
         """
-
-        state_ids = await self._state.get_current_state_ids(
-            self.room_id, prev_event_ids
-        )
-        auth_ids = self._auth.compute_auth_events(self, state_ids)
+        if auth_event_ids is None:
+            state_ids = await self._state.get_current_state_ids(
+                self.room_id, prev_event_ids
+            )
+            auth_event_ids = self._auth.compute_auth_events(self, state_ids)
 
         format_version = self.room_version.event_format
         if format_version == EventFormatVersions.V1:
             # The types of auth/prev events changes between event versions.
             auth_events = await self._store.add_event_hashes(
-                auth_ids
+                auth_event_ids
             )  # type: Union[List[str], List[Tuple[str, Dict[str, str]]]]
             prev_events = await self._store.add_event_hashes(
                 prev_event_ids
             )  # type: Union[List[str], List[Tuple[str, Dict[str, str]]]]
         else:
-            auth_events = auth_ids
+            auth_events = auth_event_ids
             prev_events = prev_event_ids
 
         old_depth = await self._store.get_max_depth_of(prev_event_ids)
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index b8f541425b..f18f882596 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -439,6 +439,7 @@ class EventCreationHandler:
         event_dict: dict,
         txn_id: Optional[str] = None,
         prev_event_ids: Optional[List[str]] = None,
+        auth_event_ids: Optional[List[str]] = None,
         require_consent: bool = True,
     ) -> Tuple[EventBase, EventContext]:
         """
@@ -458,6 +459,12 @@ class EventCreationHandler:
                 new event.
 
                 If None, they will be requested from the database.
+
+            auth_event_ids:
+                The event ids to use as the auth_events for the new event.
+                Should normally be left as None, which will cause them to be calculated
+                based on the room state at the prev_events.
+
             require_consent: Whether to check if the requester has
                 consented to the privacy policy.
         Raises:
@@ -516,7 +523,10 @@ class EventCreationHandler:
             builder.internal_metadata.txn_id = txn_id
 
         event, context = await self.create_new_client_event(
-            builder=builder, requester=requester, prev_event_ids=prev_event_ids,
+            builder=builder,
+            requester=requester,
+            prev_event_ids=prev_event_ids,
+            auth_event_ids=auth_event_ids,
         )
 
         # In an ideal world we wouldn't need the second part of this condition. However,
@@ -755,6 +765,7 @@ class EventCreationHandler:
         builder: EventBuilder,
         requester: Optional[Requester] = None,
         prev_event_ids: Optional[List[str]] = None,
+        auth_event_ids: Optional[List[str]] = None,
     ) -> Tuple[EventBase, EventContext]:
         """Create a new event for a local client
 
@@ -767,6 +778,11 @@ class EventCreationHandler:
 
                 If None, they will be requested from the database.
 
+            auth_event_ids:
+                The event ids to use as the auth_events for the new event.
+                Should normally be left as None, which will cause them to be calculated
+                based on the room state at the prev_events.
+
         Returns:
             Tuple of created event, context
         """
@@ -788,7 +804,9 @@ class EventCreationHandler:
             builder.type == EventTypes.Create or len(prev_event_ids) > 0
         ), "Attempting to create an event with no prev_events"
 
-        event = await builder.build(prev_event_ids=prev_event_ids)
+        event = await builder.build(
+            prev_event_ids=prev_event_ids, auth_event_ids=auth_event_ids
+        )
         context = await self.state.compute_event_context(event)
         if requester:
             context.app_service = requester.app_service
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index d9b98d8acd..ec784030e9 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -17,12 +17,10 @@ import abc
 import logging
 import random
 from http import HTTPStatus
-from typing import TYPE_CHECKING, Iterable, List, Optional, Tuple, Union
-
-from unpaddedbase64 import encode_base64
+from typing import TYPE_CHECKING, Iterable, List, Optional, Tuple
 
 from synapse import types
-from synapse.api.constants import MAX_DEPTH, AccountDataTypes, EventTypes, Membership
+from synapse.api.constants import AccountDataTypes, EventTypes, Membership
 from synapse.api.errors import (
     AuthError,
     Codes,
@@ -31,12 +29,8 @@ from synapse.api.errors import (
     SynapseError,
 )
 from synapse.api.ratelimiting import Ratelimiter
-from synapse.api.room_versions import EventFormatVersions
-from synapse.crypto.event_signing import compute_event_reference_hash
 from synapse.events import EventBase
-from synapse.events.builder import create_local_event_from_event_dict
 from synapse.events.snapshot import EventContext
-from synapse.events.validator import EventValidator
 from synapse.storage.roommember import RoomsForUser
 from synapse.types import JsonDict, Requester, RoomAlias, RoomID, StateMap, UserID
 from synapse.util.async_helpers import Linearizer
@@ -1132,31 +1126,10 @@ class RoomMemberMasterHandler(RoomMemberHandler):
 
         room_id = invite_event.room_id
         target_user = invite_event.state_key
-        room_version = await self.store.get_room_version(room_id)
 
         content["membership"] = Membership.LEAVE
 
-        # the auth events for the new event are the same as that of the invite, plus
-        # the invite itself.
-        #
-        # the prev_events are just the invite.
-        invite_hash = invite_event.event_id  # type: Union[str, Tuple]
-        if room_version.event_format == EventFormatVersions.V1:
-            alg, h = compute_event_reference_hash(invite_event)
-            invite_hash = (invite_event.event_id, {alg: encode_base64(h)})
-
-        auth_events = tuple(invite_event.auth_events) + (invite_hash,)
-        prev_events = (invite_hash,)
-
-        # we cap depth of generated events, to ensure that they are not
-        # rejected by other servers (and so that they can be persisted in
-        # the db)
-        depth = min(invite_event.depth + 1, MAX_DEPTH)
-
         event_dict = {
-            "depth": depth,
-            "auth_events": auth_events,
-            "prev_events": prev_events,
             "type": EventTypes.Member,
             "room_id": room_id,
             "sender": target_user,
@@ -1164,24 +1137,23 @@ class RoomMemberMasterHandler(RoomMemberHandler):
             "state_key": target_user,
         }
 
-        event = create_local_event_from_event_dict(
-            clock=self.clock,
-            hostname=self.hs.hostname,
-            signing_key=self.hs.signing_key,
-            room_version=room_version,
-            event_dict=event_dict,
+        # the auth events for the new event are the same as that of the invite, plus
+        # the invite itself.
+        #
+        # the prev_events are just the invite.
+        prev_event_ids = [invite_event.event_id]
+        auth_event_ids = invite_event.auth_event_ids() + prev_event_ids
+
+        event, context = await self.event_creation_handler.create_event(
+            requester,
+            event_dict,
+            txn_id=txn_id,
+            prev_event_ids=prev_event_ids,
+            auth_event_ids=auth_event_ids,
         )
         event.internal_metadata.outlier = True
         event.internal_metadata.out_of_band_membership = True
-        if txn_id is not None:
-            event.internal_metadata.txn_id = txn_id
-        if requester.access_token_id is not None:
-            event.internal_metadata.token_id = requester.access_token_id
-
-        EventValidator().validate_new(event, self.config)
 
-        context = await self.state_handler.compute_event_context(event)
-        context.app_service = requester.app_service
         result_event = await self.event_creation_handler.handle_new_client_event(
             requester, event, context, extra_users=[UserID.from_string(target_user)],
         )