Consistently use room_id from federation request body (#8776)

* 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.

* Kill off some references to "context"

Once upon a time, "rooms" were known as "contexts". I think this kills of the
last references to "contexts".

5 files changed, 49 insertions, 54 deletions

diff --git a/changelog.d/8776.bugfix b/changelog.d/8776.bugfix
new file mode 100644
index 0000000000..dd7ebbeb86
--- /dev/null
+++ b/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.
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 23278e36b7..4b6ab470d0 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -49,6 +49,7 @@ from synapse.federation.federation_base import FederationBase, event_from_pdu_js
 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,
@@ -391,7 +392,7 @@ class FederationServer(FederationBase):
             TRANSACTION_CONCURRENCY_LIMIT,
         )
 
-    async def on_context_state_request(
+    async def on_room_state_request(
         self, origin: str, room_id: str, event_id: str
     ) -> Tuple[int, Dict[str, Any]]:
         origin_host, _ = parse_server_name(origin)
@@ -514,11 +515,12 @@ class FederationServer(FederationBase):
         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 @@ class FederationServer(FederationBase):
         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 @@ class FederationServer(FederationBase):
         )
         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):
diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index a0933fae88..b53e7a20ec 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -440,13 +440,13 @@ class FederationEventServlet(BaseFederationServlet):
 
 
 class FederationStateV1Servlet(BaseFederationServlet):
-    PATH = "/state/(?P<context>[^/]*)/?"
+    PATH = "/state/(?P<room_id>[^/]*)/?"
 
-    # This is when someone asks for all data for a given context.
-    async def on_GET(self, origin, content, query, context):
-        return await self.handler.on_context_state_request(
+    # This is when someone asks for all data for a given room.
+    async def on_GET(self, origin, content, query, room_id):
+        return await self.handler.on_room_state_request(
             origin,
-            context,
+            room_id,
             parse_string_from_args(query, "event_id", None, required=False),
         )
 
@@ -463,16 +463,16 @@ class FederationStateIdsServlet(BaseFederationServlet):
 
 
 class FederationBackfillServlet(BaseFederationServlet):
-    PATH = "/backfill/(?P<context>[^/]*)/?"
+    PATH = "/backfill/(?P<room_id>[^/]*)/?"
 
-    async def on_GET(self, origin, content, query, context):
+    async def on_GET(self, origin, content, query, room_id):
         versions = [x.decode("ascii") for x in query[b"v"]]
         limit = parse_integer_from_args(query, "limit", None)
 
         if not limit:
             return 400, {"error": "Did not include limit param"}
 
-        return await self.handler.on_backfill_request(origin, context, versions, limit)
+        return await self.handler.on_backfill_request(origin, room_id, versions, limit)
 
 
 class FederationQueryServlet(BaseFederationServlet):
@@ -487,9 +487,9 @@ class FederationQueryServlet(BaseFederationServlet):
 
 
 class FederationMakeJoinServlet(BaseFederationServlet):
-    PATH = "/make_join/(?P<context>[^/]*)/(?P<user_id>[^/]*)"
+    PATH = "/make_join/(?P<room_id>[^/]*)/(?P<user_id>[^/]*)"
 
-    async def on_GET(self, origin, _content, query, context, user_id):
+    async def on_GET(self, origin, _content, query, room_id, user_id):
         """
         Args:
             origin (unicode): The authenticated server_name of the calling server
@@ -511,16 +511,16 @@ class FederationMakeJoinServlet(BaseFederationServlet):
             supported_versions = ["1"]
 
         content = await self.handler.on_make_join_request(
-            origin, context, user_id, supported_versions=supported_versions
+            origin, room_id, user_id, supported_versions=supported_versions
         )
         return 200, content
 
 
 class FederationMakeLeaveServlet(BaseFederationServlet):
-    PATH = "/make_leave/(?P<context>[^/]*)/(?P<user_id>[^/]*)"
+    PATH = "/make_leave/(?P<room_id>[^/]*)/(?P<user_id>[^/]*)"
 
-    async def on_GET(self, origin, content, query, context, user_id):
-        content = await self.handler.on_make_leave_request(origin, context, user_id)
+    async def on_GET(self, origin, content, query, room_id, user_id):
+        content = await self.handler.on_make_leave_request(origin, room_id, user_id)
         return 200, content
 
 
@@ -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)
 
 
@@ -538,43 +538,43 @@ 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
 
 
 class FederationEventAuthServlet(BaseFederationServlet):
-    PATH = "/event_auth/(?P<context>[^/]*)/(?P<event_id>[^/]*)"
+    PATH = "/event_auth/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
 
-    async def on_GET(self, origin, content, query, context, event_id):
-        return await self.handler.on_event_auth(origin, context, event_id)
+    async def on_GET(self, origin, content, query, room_id, event_id):
+        return await self.handler.on_event_auth(origin, room_id, 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):
-        # TODO(paul): assert that context/event_id parsed from path actually
+    async def on_PUT(self, origin, content, query, room_id, event_id):
+        # TODO(paul): assert that room_id/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):
-        # TODO(paul): assert that context/event_id parsed from path actually
+    async def on_PUT(self, origin, content, query, room_id, event_id):
+        # TODO(paul): assert that room_id/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
 
 
 class FederationV1InviteServlet(BaseFederationServlet):
-    PATH = "/invite/(?P<context>[^/]*)/(?P<event_id>[^/]*)"
+    PATH = "/invite/(?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):
         # We don't get a room version, so we have to assume its EITHER v1 or
         # v2. This is "fine" as the only difference between V1 and V2 is the
         # state resolution algorithm, and we don't use that for processing
@@ -589,12 +589,12 @@ class FederationV1InviteServlet(BaseFederationServlet):
 
 
 class FederationV2InviteServlet(BaseFederationServlet):
-    PATH = "/invite/(?P<context>[^/]*)/(?P<event_id>[^/]*)"
+    PATH = "/invite/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
 
     PREFIX = FEDERATION_V2_PREFIX
 
-    async def on_PUT(self, origin, content, query, context, event_id):
-        # TODO(paul): assert that context/event_id parsed from path actually
+    async def on_PUT(self, origin, content, query, room_id, event_id):
+        # TODO(paul): assert that room_id/event_id parsed from path actually
         #   match those given in content
 
         room_version = content["room_version"]
@@ -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
 
 
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index c386957706..e03caea251 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -55,6 +55,7 @@ from synapse.events import EventBase
 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,
@@ -2686,7 +2687,7 @@ class FederationHandler(BaseHandler):
             )
 
     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
 
@@ -2694,12 +2695,11 @@ class FederationHandler(BaseHandler):
         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.
diff --git a/tests/handlers/test_federation.py b/tests/handlers/test_federation.py
index 9ef80fe502..bf866dacf3 100644
--- a/tests/handlers/test_federation.py
+++ b/tests/handlers/test_federation.py
@@ -59,7 +59,6 @@ class FederationTestCase(unittest.HomeserverTestCase):
         )
 
         d = self.handler.on_exchange_third_party_invite_request(
-            room_id=room_id,
             event_dict={
                 "type": EventTypes.Member,
                 "room_id": room_id,