Consistently use room_id from federation request body

Some federation APIs have a redundant `room_id` path param (see
https://github.com/matrix-org/matrix-doc/issues/2330). We should make sure we
consistently use either the path param or the body param, and the body param is
easier.

changelog.d/8776.bugfix

@@ -0,0 +1 @@
+Fix a bug in some federation APIs which could lead to unexpected behaviour if different parameters were set in the URI and the request body.

synapse/federation/federation_server.py

@@ -49,6 +49,7 @@
 from synapse.federation.persistence import TransactionActions
 from synapse.federation.units import Edu, Transaction
 from synapse.http.endpoint import parse_server_name
+from synapse.http.servlet import assert_params_in_dict
 from synapse.logging.context import (
     make_deferred_yieldable,
     nested_logging_context,
@@ -514,11 +515,12 @@ async def on_invite_request(
         return {"event": ret_pdu.get_pdu_json(time_now)}
 
     async def on_send_join_request(
-        self, origin: str, content: JsonDict, room_id: str
+        self, origin: str, content: JsonDict
     ) -> Dict[str, Any]:
         logger.debug("on_send_join_request: content: %s", content)
 
-        room_version = await self.store.get_room_version(room_id)
+        assert_params_in_dict(content, ["room_id"])
+        room_version = await self.store.get_room_version(content["room_id"])
         pdu = event_from_pdu_json(content, room_version)
 
         origin_host, _ = parse_server_name(origin)
@@ -547,12 +549,11 @@ async def on_make_leave_request(
         time_now = self._clock.time_msec()
         return {"event": pdu.get_pdu_json(time_now), "room_version": room_version}
 
-    async def on_send_leave_request(
-        self, origin: str, content: JsonDict, room_id: str
-    ) -> dict:
+    async def on_send_leave_request(self, origin: str, content: JsonDict) -> dict:
         logger.debug("on_send_leave_request: content: %s", content)
 
-        room_version = await self.store.get_room_version(room_id)
+        assert_params_in_dict(content, ["room_id"])
+        room_version = await self.store.get_room_version(content["room_id"])
         pdu = event_from_pdu_json(content, room_version)
 
         origin_host, _ = parse_server_name(origin)
@@ -748,12 +749,8 @@ async def exchange_third_party_invite(
         )
         return ret
 
-    async def on_exchange_third_party_invite_request(
-        self, room_id: str, event_dict: Dict
-    ):
-        ret = await self.handler.on_exchange_third_party_invite_request(
-            room_id, event_dict
-        )
+    async def on_exchange_third_party_invite_request(self, event_dict: Dict):
+        ret = await self.handler.on_exchange_third_party_invite_request(event_dict)
         return ret
 
     async def check_server_matches_acl(self, server_name: str, room_id: str):

synapse/federation/transport/server.py

@@ -528,7 +528,7 @@ class FederationV1SendLeaveServlet(BaseFederationServlet):
     PATH = "/send_leave/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
 
     async def on_PUT(self, origin, content, query, room_id, event_id):
-        content = await self.handler.on_send_leave_request(origin, content, room_id)
+        content = await self.handler.on_send_leave_request(origin, content)
         return 200, (200, content)
 
 
@@ -538,7 +538,7 @@ class FederationV2SendLeaveServlet(BaseFederationServlet):
     PREFIX = FEDERATION_V2_PREFIX
 
     async def on_PUT(self, origin, content, query, room_id, event_id):
-        content = await self.handler.on_send_leave_request(origin, content, room_id)
+        content = await self.handler.on_send_leave_request(origin, content)
         return 200, content
 
 
@@ -550,24 +550,24 @@ async def on_GET(self, origin, content, query, context, event_id):
 
 
 class FederationV1SendJoinServlet(BaseFederationServlet):
-    PATH = "/send_join/(?P<context>[^/]*)/(?P<event_id>[^/]*)"
+    PATH = "/send_join/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
 
-    async def on_PUT(self, origin, content, query, context, event_id):
+    async def on_PUT(self, origin, content, query, room_id, event_id):
         # TODO(paul): assert that context/event_id parsed from path actually
         #   match those given in content
-        content = await self.handler.on_send_join_request(origin, content, context)
+        content = await self.handler.on_send_join_request(origin, content)
         return 200, (200, content)
 
 
 class FederationV2SendJoinServlet(BaseFederationServlet):
-    PATH = "/send_join/(?P<context>[^/]*)/(?P<event_id>[^/]*)"
+    PATH = "/send_join/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
 
     PREFIX = FEDERATION_V2_PREFIX
 
-    async def on_PUT(self, origin, content, query, context, event_id):
+    async def on_PUT(self, origin, content, query, room_id, event_id):
         # TODO(paul): assert that context/event_id parsed from path actually
         #   match those given in content
-        content = await self.handler.on_send_join_request(origin, content, context)
+        content = await self.handler.on_send_join_request(origin, content)
         return 200, content
 
 
@@ -616,9 +616,7 @@ class FederationThirdPartyInviteExchangeServlet(BaseFederationServlet):
     PATH = "/exchange_third_party_invite/(?P<room_id>[^/]*)"
 
     async def on_PUT(self, origin, content, query, room_id):
-        content = await self.handler.on_exchange_third_party_invite_request(
-            room_id, content
-        )
+        content = await self.handler.on_exchange_third_party_invite_request(content)
         return 200, content
 
 

synapse/handlers/federation.py

@@ -55,6 +55,7 @@
 from synapse.events.snapshot import EventContext
 from synapse.events.validator import EventValidator
 from synapse.handlers._base import BaseHandler
+from synapse.http.servlet import assert_params_in_dict
 from synapse.logging.context import (
     make_deferred_yieldable,
     nested_logging_context,
@@ -2688,20 +2689,19 @@ async def exchange_third_party_invite(
             )
 
     async def on_exchange_third_party_invite_request(
-        self, room_id: str, event_dict: JsonDict
+        self, event_dict: JsonDict
     ) -> None:
         """Handle an exchange_third_party_invite request from a remote server
 
         The remote server will call this when it wants to turn a 3pid invite
         into a normal m.room.member invite.
 
         Args:
-            room_id: The ID of the room.
-
-            event_dict (dict[str, Any]): Dictionary containing the event body.
+            event_dict: Dictionary containing the event body.
 
         """
-        room_version = await self.store.get_room_version_id(room_id)
+        assert_params_in_dict(event_dict, ["room_id"])
+        room_version = await self.store.get_room_version_id(event_dict["room_id"])
 
         # NB: event_dict has a particular specced format we might need to fudge
         # if we change event formats too much.