Implement knock feature (#6739)

This PR aims to implement the knock feature as proposed in https://github.com/matrix-org/matrix-doc/pull/2403

Signed-off-by: Sorunome mail@sorunome.de
Signed-off-by: Andrew Morgan andrewm@element.io

1 files changed, 12 insertions, 7 deletions

diff --git a/synapse/events/utils.py b/synapse/events/utils.py

index 7d7cd9aaee..ec96999e4e 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -242,6 +242,7 @@ def format_event_for_client_v1(d):
         "replaces_state",
         "prev_content",
         "invite_room_state",
+        "knock_room_state",
     )
     for key in copy_keys:
         if key in d["unsigned"]:
@@ -278,7 +279,7 @@ def serialize_event(
     event_format=format_event_for_client_v1,
     token_id=None,
     only_event_fields=None,
-    is_invite=False,
+    include_stripped_room_state=False,
 ):
     """Serialize event for clients
 
@@ -289,8 +290,10 @@ def serialize_event(
         event_format
         token_id
         only_event_fields
-        is_invite (bool): Whether this is an invite that is being sent to the
-            invitee
+        include_stripped_room_state (bool): Some events can have stripped room state
+            stored in the `unsigned` field. This is required for invite and knock
+            functionality. If this option is False, that state will be removed from the
+            event before it is returned. Otherwise, it will be kept.
 
     Returns:
         dict
@@ -322,11 +325,13 @@ def serialize_event(
             if txn_id is not None:
                 d["unsigned"]["transaction_id"] = txn_id
 
-    # If this is an invite for somebody else, then we don't care about the
-    # invite_room_state as that's meant solely for the invitee. Other clients
-    # will already have the state since they're in the room.
-    if not is_invite:
+    # invite_room_state and knock_room_state are a list of stripped room state events
+    # that are meant to provide metadata about a room to an invitee/knocker. They are
+    # intended to only be included in specific circumstances, such as down sync, and
+    # should not be included in any other case.
+    if not include_stripped_room_state:
         d["unsigned"].pop("invite_room_state", None)
+        d["unsigned"].pop("knock_room_state", None)
 
     if as_client_event:
         d = event_format(d)