Support the stable /hierarchy endpoint from MSC2946 (#11329)

This also makes additional updates where the implementation
had drifted from the approved MSC.

Unstable endpoints will be removed at a later data.

6 files changed, 64 insertions, 18 deletions

diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index 7e09530ad2..52541faab2 100644
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -194,6 +194,7 @@ class SynapseHomeServer(HomeServer):
                 {
                     "/_matrix/client/api/v1": client_resource,
                     "/_matrix/client/r0": client_resource,
+                    "/_matrix/client/v1": client_resource,
                     "/_matrix/client/v3": client_resource,
                     "/_matrix/client/unstable": client_resource,
                     "/_matrix/client/v2_alpha": client_resource,
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index 3b85b135e0..bc3f96c1fc 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -1395,11 +1395,28 @@ class FederationClient(FederationBase):
         async def send_request(
             destination: str,
         ) -> Tuple[JsonDict, Sequence[JsonDict], Sequence[str]]:
-            res = await self.transport_layer.get_room_hierarchy(
-                destination=destination,
-                room_id=room_id,
-                suggested_only=suggested_only,
-            )
+            try:
+                res = await self.transport_layer.get_room_hierarchy(
+                    destination=destination,
+                    room_id=room_id,
+                    suggested_only=suggested_only,
+                )
+            except HttpResponseException as e:
+                # If an error is received that is due to an unrecognised endpoint,
+                # fallback to the unstable endpoint. Otherwise consider it a
+                # legitmate error and raise.
+                if not self._is_unknown_endpoint(e):
+                    raise
+
+                logger.debug(
+                    "Couldn't fetch room hierarchy with the v1 API, falling back to the unstable API"
+                )
+
+                res = await self.transport_layer.get_room_hierarchy_unstable(
+                    destination=destination,
+                    room_id=room_id,
+                    suggested_only=suggested_only,
+                )
 
             room = res.get("room")
             if not isinstance(room, dict):
@@ -1449,6 +1466,10 @@ class FederationClient(FederationBase):
             if e.code != 502:
                 raise
 
+            logger.debug(
+                "Couldn't fetch room hierarchy, falling back to the spaces API"
+            )
+
             # Fallback to the old federation API and translate the results if
             # no servers implement the new API.
             #
diff --git a/synapse/federation/transport/client.py b/synapse/federation/transport/client.py
index 0fea221165..fe29bcfd4b 100644
--- a/synapse/federation/transport/client.py
+++ b/synapse/federation/transport/client.py
@@ -1192,10 +1192,24 @@ class TransportLayerClient:
         )
 
     async def get_room_hierarchy(
-        self,
-        destination: str,
-        room_id: str,
-        suggested_only: bool,
+        self, destination: str, room_id: str, suggested_only: bool
+    ) -> JsonDict:
+        """
+        Args:
+            destination: The remote server
+            room_id: The room ID to ask about.
+            suggested_only: if True, only suggested rooms will be returned
+        """
+        path = _create_v1_path("/hierarchy/%s", room_id)
+
+        return await self.client.get_json(
+            destination=destination,
+            path=path,
+            args={"suggested_only": "true" if suggested_only else "false"},
+        )
+
+    async def get_room_hierarchy_unstable(
+        self, destination: str, room_id: str, suggested_only: bool
     ) -> JsonDict:
         """
         Args:
diff --git a/synapse/federation/transport/server/federation.py b/synapse/federation/transport/server/federation.py
index 2fdf6cc99e..66e915228c 100644
--- a/synapse/federation/transport/server/federation.py
+++ b/synapse/federation/transport/server/federation.py
@@ -611,7 +611,6 @@ class FederationSpaceSummaryServlet(BaseFederationServlet):
 
 
 class FederationRoomHierarchyServlet(BaseFederationServlet):
-    PREFIX = FEDERATION_UNSTABLE_PREFIX + "/org.matrix.msc2946"
     PATH = "/hierarchy/(?P<room_id>[^/]*)"
 
     def __init__(
@@ -637,6 +636,10 @@ class FederationRoomHierarchyServlet(BaseFederationServlet):
         )
 
 
+class FederationRoomHierarchyUnstableServlet(FederationRoomHierarchyServlet):
+    PREFIX = FEDERATION_UNSTABLE_PREFIX + "/org.matrix.msc2946"
+
+
 class RoomComplexityServlet(BaseFederationServlet):
     """
     Indicates to other servers how complex (and therefore likely
@@ -701,6 +704,7 @@ FEDERATION_SERVLET_CLASSES: Tuple[Type[BaseFederationServlet], ...] = (
     RoomComplexityServlet,
     FederationSpaceSummaryServlet,
     FederationRoomHierarchyServlet,
+    FederationRoomHierarchyUnstableServlet,
     FederationV1SendKnockServlet,
     FederationMakeKnockServlet,
 )
diff --git a/synapse/handlers/room_summary.py b/synapse/handlers/room_summary.py
index 8181cc0b52..b2cfe537df 100644
--- a/synapse/handlers/room_summary.py
+++ b/synapse/handlers/room_summary.py
@@ -36,8 +36,9 @@ from synapse.api.errors import (
     SynapseError,
     UnsupportedRoomVersionError,
 )
+from synapse.api.ratelimiting import Ratelimiter
 from synapse.events import EventBase
-from synapse.types import JsonDict
+from synapse.types import JsonDict, Requester
 from synapse.util.caches.response_cache import ResponseCache
 
 if TYPE_CHECKING:
@@ -93,6 +94,9 @@ class RoomSummaryHandler:
         self._event_serializer = hs.get_event_client_serializer()
         self._server_name = hs.hostname
         self._federation_client = hs.get_federation_client()
+        self._ratelimiter = Ratelimiter(
+            store=self._store, clock=hs.get_clock(), rate_hz=5, burst_count=10
+        )
 
         # If a user tries to fetch the same page multiple times in quick succession,
         # only process the first attempt and return its result to subsequent requests.
@@ -249,7 +253,7 @@ class RoomSummaryHandler:
 
     async def get_room_hierarchy(
         self,
-        requester: str,
+        requester: Requester,
         requested_room_id: str,
         suggested_only: bool = False,
         max_depth: Optional[int] = None,
@@ -276,6 +280,8 @@ class RoomSummaryHandler:
         Returns:
             The JSON hierarchy dictionary.
         """
+        await self._ratelimiter.ratelimit(requester)
+
         # If a user tries to fetch the same page multiple times in quick succession,
         # only process the first attempt and return its result to subsequent requests.
         #
@@ -283,7 +289,7 @@ class RoomSummaryHandler:
         # to process multiple requests for the same page will result in errors.
         return await self._pagination_response_cache.wrap(
             (
-                requester,
+                requester.user.to_string(),
                 requested_room_id,
                 suggested_only,
                 max_depth,
@@ -291,7 +297,7 @@ class RoomSummaryHandler:
                 from_token,
             ),
             self._get_room_hierarchy,
-            requester,
+            requester.user.to_string(),
             requested_room_id,
             suggested_only,
             max_depth,
diff --git a/synapse/rest/client/room.py b/synapse/rest/client/room.py
index 955d4e8641..73d0f7c950 100644
--- a/synapse/rest/client/room.py
+++ b/synapse/rest/client/room.py
@@ -1138,12 +1138,12 @@ class RoomSpaceSummaryRestServlet(RestServlet):
 
 
 class RoomHierarchyRestServlet(RestServlet):
-    PATTERNS = (
+    PATTERNS = [
         re.compile(
-            "^/_matrix/client/unstable/org.matrix.msc2946"
+            "^/_matrix/client/(v1|unstable/org.matrix.msc2946)"
             "/rooms/(?P<room_id>[^/]*)/hierarchy$"
         ),
-    )
+    ]
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -1168,7 +1168,7 @@ class RoomHierarchyRestServlet(RestServlet):
             )
 
         return 200, await self._room_summary_handler.get_room_hierarchy(
-            requester.user.to_string(),
+            requester,
             room_id,
             suggested_only=parse_boolean(request, "suggested_only", default=False),
             max_depth=max_depth,