Implement account status endpoints (MSC3720) (#12001)

See matrix-org/matrix-doc#3720

Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>

1 files changed, 59 insertions, 1 deletions

diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index c2997997da..2121e92e3a 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -56,7 +56,7 @@ from synapse.api.room_versions import (
 from synapse.events import EventBase, builder
 from synapse.federation.federation_base import FederationBase, event_from_pdu_json
 from synapse.federation.transport.client import SendJoinResponse
-from synapse.types import JsonDict, get_domain_from_id
+from synapse.types import JsonDict, UserID, get_domain_from_id
 from synapse.util.async_helpers import concurrently_execute
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.retryutils import NotRetryingDestination
@@ -1610,6 +1610,64 @@ class FederationClient(FederationBase):
         except ValueError as e:
             raise InvalidResponseError(str(e))
 
+    async def get_account_status(
+        self, destination: str, user_ids: List[str]
+    ) -> Tuple[JsonDict, List[str]]:
+        """Retrieves account statuses for a given list of users on a given remote
+        homeserver.
+
+        If the request fails for any reason, all user IDs for this destination are marked
+        as failed.
+
+        Args:
+            destination: the destination to contact
+            user_ids: the user ID(s) for which to request account status(es)
+
+        Returns:
+            The account statuses, as well as the list of user IDs for which it was not
+            possible to retrieve a status.
+        """
+        try:
+            res = await self.transport_layer.get_account_status(destination, user_ids)
+        except Exception:
+            # If the query failed for any reason, mark all the users as failed.
+            return {}, user_ids
+
+        statuses = res.get("account_statuses", {})
+        failures = res.get("failures", [])
+
+        if not isinstance(statuses, dict) or not isinstance(failures, list):
+            # Make sure we're not feeding back malformed data back to the caller.
+            logger.warning(
+                "Destination %s responded with malformed data to account_status query",
+                destination,
+            )
+            return {}, user_ids
+
+        for user_id in user_ids:
+            # Any account whose status is missing is a user we failed to receive the
+            # status of.
+            if user_id not in statuses and user_id not in failures:
+                failures.append(user_id)
+
+        # Filter out any user ID that doesn't belong to the remote server that sent its
+        # status (or failure).
+        def filter_user_id(user_id: str) -> bool:
+            try:
+                return UserID.from_string(user_id).domain == destination
+            except SynapseError:
+                # If the user ID doesn't parse, ignore it.
+                return False
+
+        filtered_statuses = dict(
+            # item is a (key, value) tuple, so item[0] is the user ID.
+            filter(lambda item: filter_user_id(item[0]), statuses.items())
+        )
+
+        filtered_failures = list(filter(filter_user_id, failures))
+
+        return filtered_statuses, filtered_failures
+
 
 @attr.s(frozen=True, slots=True, auto_attribs=True)
 class TimestampToEventResponse: