Add additional types to the federation transport server. (#10213)

3 files changed, 521 insertions, 118 deletions

diff --git a/changelog.d/10213.misc b/changelog.d/10213.misc
new file mode 100644
index 0000000000..9adb0fbd02
--- /dev/null
+++ b/changelog.d/10213.misc
@@ -0,0 +1 @@
+Add type hints to the federation servlets.
diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index 676fbd3750..d37d9565fc 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -15,7 +15,19 @@
 import functools
 import logging
 import re
-from typing import Container, Mapping, Optional, Sequence, Tuple, Type
+from typing import (
+    Container,
+    Dict,
+    List,
+    Mapping,
+    Optional,
+    Sequence,
+    Tuple,
+    Type,
+    Union,
+)
+
+from typing_extensions import Literal
 
 import synapse
 from synapse.api.constants import MAX_GROUP_CATEGORYID_LENGTH, MAX_GROUP_ROLEID_LENGTH
@@ -56,15 +68,15 @@ logger = logging.getLogger(__name__)
 class TransportLayerServer(JsonResource):
     """Handles incoming federation HTTP requests"""
 
-    def __init__(self, hs, servlet_groups=None):
+    def __init__(self, hs: HomeServer, servlet_groups: Optional[List[str]] = None):
         """Initialize the TransportLayerServer
 
         Will by default register all servlets. For custom behaviour, pass in
         a list of servlet_groups to register.
 
         Args:
-            hs (synapse.server.HomeServer): homeserver
-            servlet_groups (list[str], optional): List of servlet groups to register.
+            hs: homeserver
+            servlet_groups: List of servlet groups to register.
                 Defaults to ``DEFAULT_SERVLET_GROUPS``.
         """
         self.hs = hs
@@ -78,7 +90,7 @@ class TransportLayerServer(JsonResource):
 
         self.register_servlets()
 
-    def register_servlets(self):
+    def register_servlets(self) -> None:
         register_servlets(
             self.hs,
             resource=self,
@@ -91,14 +103,10 @@ class TransportLayerServer(JsonResource):
 class AuthenticationError(SynapseError):
     """There was a problem authenticating the request"""
 
-    pass
-
 
 class NoAuthenticationError(AuthenticationError):
     """The request had no authentication information"""
 
-    pass
-
 
 class Authenticator:
     def __init__(self, hs: HomeServer):
@@ -410,13 +418,18 @@ class FederationSendServlet(BaseFederationServerServlet):
     RATELIMIT = False
 
     # This is when someone is trying to send us a bunch of data.
-    async def on_PUT(self, origin, content, query, transaction_id):
+    async def on_PUT(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        transaction_id: str,
+    ) -> Tuple[int, JsonDict]:
         """Called on PUT /send/<transaction_id>/
 
         Args:
-            request (twisted.web.http.Request): The HTTP request.
-            transaction_id (str): The transaction_id associated with this
-                request. This is *not* None.
+            transaction_id: The transaction_id associated with this request. This
+                is *not* None.
 
         Returns:
             Tuple of `(code, response)`, where
@@ -461,7 +474,13 @@ class FederationEventServlet(BaseFederationServerServlet):
     PATH = "/event/(?P<event_id>[^/]*)/?"
 
     # This is when someone asks for a data item for a given server data_id pair.
-    async def on_GET(self, origin, content, query, event_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        event_id: str,
+    ) -> Tuple[int, Union[JsonDict, str]]:
         return await self.handler.on_pdu_request(origin, event_id)
 
 
@@ -469,7 +488,13 @@ class FederationStateV1Servlet(BaseFederationServerServlet):
     PATH = "/state/(?P<room_id>[^/]*)/?"
 
     # This is when someone asks for all data for a given room.
-    async def on_GET(self, origin, content, query, room_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+    ) -> Tuple[int, JsonDict]:
         return await self.handler.on_room_state_request(
             origin,
             room_id,
@@ -480,7 +505,13 @@ class FederationStateV1Servlet(BaseFederationServerServlet):
 class FederationStateIdsServlet(BaseFederationServerServlet):
     PATH = "/state_ids/(?P<room_id>[^/]*)/?"
 
-    async def on_GET(self, origin, content, query, room_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+    ) -> Tuple[int, JsonDict]:
         return await self.handler.on_state_ids_request(
             origin,
             room_id,
@@ -491,7 +522,13 @@ class FederationStateIdsServlet(BaseFederationServerServlet):
 class FederationBackfillServlet(BaseFederationServerServlet):
     PATH = "/backfill/(?P<room_id>[^/]*)/?"
 
-    async def on_GET(self, origin, content, query, room_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+    ) -> Tuple[int, JsonDict]:
         versions = [x.decode("ascii") for x in query[b"v"]]
         limit = parse_integer_from_args(query, "limit", None)
 
@@ -505,7 +542,13 @@ class FederationQueryServlet(BaseFederationServerServlet):
     PATH = "/query/(?P<query_type>[^/]*)"
 
     # This is when we receive a server-server Query
-    async def on_GET(self, origin, content, query, query_type):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        query_type: str,
+    ) -> Tuple[int, JsonDict]:
         args = {k.decode("utf8"): v[0].decode("utf-8") for k, v in query.items()}
         args["origin"] = origin
         return await self.handler.on_query_request(query_type, args)
@@ -514,47 +557,66 @@ class FederationQueryServlet(BaseFederationServerServlet):
 class FederationMakeJoinServlet(BaseFederationServerServlet):
     PATH = "/make_join/(?P<room_id>[^/]*)/(?P<user_id>[^/]*)"
 
-    async def on_GET(self, origin, _content, query, room_id, user_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+        user_id: str,
+    ) -> Tuple[int, JsonDict]:
         """
         Args:
-            origin (unicode): The authenticated server_name of the calling server
+            origin: The authenticated server_name of the calling server
 
-            _content (None): (GETs don't have bodies)
+            content: (GETs don't have bodies)
 
-            query (dict[bytes, list[bytes]]): Query params from the request.
+            query: Query params from the request.
 
-            **kwargs (dict[unicode, unicode]): the dict mapping keys to path
-                components as specified in the path match regexp.
+            **kwargs: the dict mapping keys to path components as specified in
+                the path match regexp.
 
         Returns:
-            Tuple[int, object]: (response code, response object)
+            Tuple of (response code, response object)
         """
-        versions = query.get(b"ver")
-        if versions is not None:
-            supported_versions = [v.decode("utf-8") for v in versions]
-        else:
+        supported_versions = parse_strings_from_args(query, "ver", encoding="utf-8")
+        if supported_versions is None:
             supported_versions = ["1"]
 
-        content = await self.handler.on_make_join_request(
+        result = await self.handler.on_make_join_request(
             origin, room_id, user_id, supported_versions=supported_versions
         )
-        return 200, content
+        return 200, result
 
 
 class FederationMakeLeaveServlet(BaseFederationServerServlet):
     PATH = "/make_leave/(?P<room_id>[^/]*)/(?P<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
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+        user_id: str,
+    ) -> Tuple[int, JsonDict]:
+        result = await self.handler.on_make_leave_request(origin, room_id, user_id)
+        return 200, result
 
 
 class FederationV1SendLeaveServlet(BaseFederationServerServlet):
     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)
-        return 200, (200, content)
+    async def on_PUT(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+        event_id: str,
+    ) -> Tuple[int, Tuple[int, JsonDict]]:
+        result = await self.handler.on_send_leave_request(origin, content, room_id)
+        return 200, (200, result)
 
 
 class FederationV2SendLeaveServlet(BaseFederationServerServlet):
@@ -562,50 +624,84 @@ class FederationV2SendLeaveServlet(BaseFederationServerServlet):
 
     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)
-        return 200, content
+    async def on_PUT(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+        event_id: str,
+    ) -> Tuple[int, JsonDict]:
+        result = await self.handler.on_send_leave_request(origin, content, room_id)
+        return 200, result
 
 
 class FederationMakeKnockServlet(BaseFederationServerServlet):
     PATH = "/make_knock/(?P<room_id>[^/]*)/(?P<user_id>[^/]*)"
 
-    async def on_GET(self, origin, content, query, room_id, user_id):
-        try:
-            # Retrieve the room versions the remote homeserver claims to support
-            supported_versions = parse_strings_from_args(query, "ver", encoding="utf-8")
-        except KeyError:
-            raise SynapseError(400, "Missing required query parameter 'ver'")
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+        user_id: str,
+    ) -> Tuple[int, JsonDict]:
+        # Retrieve the room versions the remote homeserver claims to support
+        supported_versions = parse_strings_from_args(
+            query, "ver", required=True, encoding="utf-8"
+        )
 
-        content = await self.handler.on_make_knock_request(
+        result = await self.handler.on_make_knock_request(
             origin, room_id, user_id, supported_versions=supported_versions
         )
-        return 200, content
+        return 200, result
 
 
 class FederationV1SendKnockServlet(BaseFederationServerServlet):
     PATH = "/send_knock/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
 
-    async def on_PUT(self, origin, content, query, room_id, event_id):
-        content = await self.handler.on_send_knock_request(origin, content, room_id)
-        return 200, content
+    async def on_PUT(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+        event_id: str,
+    ) -> Tuple[int, JsonDict]:
+        result = await self.handler.on_send_knock_request(origin, content, room_id)
+        return 200, result
 
 
 class FederationEventAuthServlet(BaseFederationServerServlet):
     PATH = "/event_auth/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
 
-    async def on_GET(self, origin, content, query, room_id, event_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+        event_id: str,
+    ) -> Tuple[int, JsonDict]:
         return await self.handler.on_event_auth(origin, room_id, event_id)
 
 
 class FederationV1SendJoinServlet(BaseFederationServerServlet):
     PATH = "/send_join/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
 
-    async def on_PUT(self, origin, content, query, room_id, event_id):
+    async def on_PUT(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+        event_id: str,
+    ) -> Tuple[int, Tuple[int, JsonDict]]:
         # TODO(paul): assert that event_id parsed from path actually
         #   match those given in content
-        content = await self.handler.on_send_join_request(origin, content, room_id)
-        return 200, (200, content)
+        result = await self.handler.on_send_join_request(origin, content, room_id)
+        return 200, (200, result)
 
 
 class FederationV2SendJoinServlet(BaseFederationServerServlet):
@@ -613,28 +709,42 @@ class FederationV2SendJoinServlet(BaseFederationServerServlet):
 
     PREFIX = FEDERATION_V2_PREFIX
 
-    async def on_PUT(self, origin, content, query, room_id, event_id):
+    async def on_PUT(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+        event_id: str,
+    ) -> Tuple[int, JsonDict]:
         # TODO(paul): assert that event_id parsed from path actually
         #   match those given in content
-        content = await self.handler.on_send_join_request(origin, content, room_id)
-        return 200, content
+        result = await self.handler.on_send_join_request(origin, content, room_id)
+        return 200, result
 
 
 class FederationV1InviteServlet(BaseFederationServerServlet):
     PATH = "/invite/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
 
-    async def on_PUT(self, origin, content, query, room_id, event_id):
+    async def on_PUT(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+        event_id: str,
+    ) -> Tuple[int, Tuple[int, JsonDict]]:
         # 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
         # invites
-        content = await self.handler.on_invite_request(
+        result = await self.handler.on_invite_request(
             origin, content, room_version_id=RoomVersions.V1.identifier
         )
 
         # V1 federation API is defined to return a content of `[200, {...}]`
         # due to a historical bug.
-        return 200, (200, content)
+        return 200, (200, result)
 
 
 class FederationV2InviteServlet(BaseFederationServerServlet):
@@ -642,7 +752,14 @@ class FederationV2InviteServlet(BaseFederationServerServlet):
 
     PREFIX = FEDERATION_V2_PREFIX
 
-    async def on_PUT(self, origin, content, query, room_id, event_id):
+    async def on_PUT(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+        event_id: str,
+    ) -> Tuple[int, JsonDict]:
         # TODO(paul): assert that room_id/event_id parsed from path actually
         #   match those given in content
 
@@ -655,16 +772,22 @@ class FederationV2InviteServlet(BaseFederationServerServlet):
 
         event.setdefault("unsigned", {})["invite_room_state"] = invite_room_state
 
-        content = await self.handler.on_invite_request(
+        result = await self.handler.on_invite_request(
             origin, event, room_version_id=room_version
         )
-        return 200, content
+        return 200, result
 
 
 class FederationThirdPartyInviteExchangeServlet(BaseFederationServerServlet):
     PATH = "/exchange_third_party_invite/(?P<room_id>[^/]*)"
 
-    async def on_PUT(self, origin, content, query, room_id):
+    async def on_PUT(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+    ) -> Tuple[int, JsonDict]:
         await self.handler.on_exchange_third_party_invite_request(content)
         return 200, {}
 
@@ -672,21 +795,31 @@ class FederationThirdPartyInviteExchangeServlet(BaseFederationServerServlet):
 class FederationClientKeysQueryServlet(BaseFederationServerServlet):
     PATH = "/user/keys/query"
 
-    async def on_POST(self, origin, content, query):
+    async def on_POST(
+        self, origin: str, content: JsonDict, query: Dict[bytes, List[bytes]]
+    ) -> Tuple[int, JsonDict]:
         return await self.handler.on_query_client_keys(origin, content)
 
 
 class FederationUserDevicesQueryServlet(BaseFederationServerServlet):
     PATH = "/user/devices/(?P<user_id>[^/]*)"
 
-    async def on_GET(self, origin, content, query, user_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        user_id: str,
+    ) -> Tuple[int, JsonDict]:
         return await self.handler.on_query_user_devices(origin, user_id)
 
 
 class FederationClientKeysClaimServlet(BaseFederationServerServlet):
     PATH = "/user/keys/claim"
 
-    async def on_POST(self, origin, content, query):
+    async def on_POST(
+        self, origin: str, content: JsonDict, query: Dict[bytes, List[bytes]]
+    ) -> Tuple[int, JsonDict]:
         response = await self.handler.on_claim_client_keys(origin, content)
         return 200, response
 
@@ -695,12 +828,18 @@ class FederationGetMissingEventsServlet(BaseFederationServerServlet):
     # TODO(paul): Why does this path alone end with "/?" optional?
     PATH = "/get_missing_events/(?P<room_id>[^/]*)/?"
 
-    async def on_POST(self, origin, content, query, room_id):
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+    ) -> Tuple[int, JsonDict]:
         limit = int(content.get("limit", 10))
         earliest_events = content.get("earliest_events", [])
         latest_events = content.get("latest_events", [])
 
-        content = await self.handler.on_get_missing_events(
+        result = await self.handler.on_get_missing_events(
             origin,
             room_id=room_id,
             earliest_events=earliest_events,
@@ -708,7 +847,7 @@ class FederationGetMissingEventsServlet(BaseFederationServerServlet):
             limit=limit,
         )
 
-        return 200, content
+        return 200, result
 
 
 class On3pidBindServlet(BaseFederationServerServlet):
@@ -716,7 +855,9 @@ class On3pidBindServlet(BaseFederationServerServlet):
 
     REQUIRE_AUTH = False
 
-    async def on_POST(self, origin, content, query):
+    async def on_POST(
+        self, origin: Optional[str], content: JsonDict, query: Dict[bytes, List[bytes]]
+    ) -> Tuple[int, JsonDict]:
         if "invites" in content:
             last_exception = None
             for invite in content["invites"]:
@@ -762,15 +903,20 @@ class OpenIdUserInfo(BaseFederationServerServlet):
 
     REQUIRE_AUTH = False
 
-    async def on_GET(self, origin, content, query):
-        token = query.get(b"access_token", [None])[0]
+    async def on_GET(
+        self,
+        origin: Optional[str],
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+    ) -> Tuple[int, JsonDict]:
+        token = parse_string_from_args(query, "access_token")
         if token is None:
             return (
                 401,
                 {"errcode": "M_MISSING_TOKEN", "error": "Access Token required"},
             )
 
-        user_id = await self.handler.on_openid_userinfo(token.decode("ascii"))
+        user_id = await self.handler.on_openid_userinfo(token)
 
         if user_id is None:
             return (
@@ -829,7 +975,9 @@ class PublicRoomList(BaseFederationServlet):
         self.handler = hs.get_room_list_handler()
         self.allow_access = allow_access
 
-    async def on_GET(self, origin, content, query):
+    async def on_GET(
+        self, origin: str, content: Literal[None], query: Dict[bytes, List[bytes]]
+    ) -> Tuple[int, JsonDict]:
         if not self.allow_access:
             raise FederationDeniedError(origin)
 
@@ -858,7 +1006,9 @@ class PublicRoomList(BaseFederationServlet):
         )
         return 200, data
 
-    async def on_POST(self, origin, content, query):
+    async def on_POST(
+        self, origin: str, content: JsonDict, query: Dict[bytes, List[bytes]]
+    ) -> Tuple[int, JsonDict]:
         # This implements MSC2197 (Search Filtering over Federation)
         if not self.allow_access:
             raise FederationDeniedError(origin)
@@ -904,7 +1054,12 @@ class FederationVersionServlet(BaseFederationServlet):
 
     REQUIRE_AUTH = False
 
-    async def on_GET(self, origin, content, query):
+    async def on_GET(
+        self,
+        origin: Optional[str],
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+    ) -> Tuple[int, JsonDict]:
         return (
             200,
             {"server": {"name": "Synapse", "version": get_version_string(synapse)}},
@@ -933,7 +1088,13 @@ class FederationGroupsProfileServlet(BaseGroupsServerServlet):
 
     PATH = "/groups/(?P<group_id>[^/]*)/profile"
 
-    async def on_GET(self, origin, content, query, group_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -942,7 +1103,13 @@ class FederationGroupsProfileServlet(BaseGroupsServerServlet):
 
         return 200, new_content
 
-    async def on_POST(self, origin, content, query, group_id):
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -957,7 +1124,13 @@ class FederationGroupsProfileServlet(BaseGroupsServerServlet):
 class FederationGroupsSummaryServlet(BaseGroupsServerServlet):
     PATH = "/groups/(?P<group_id>[^/]*)/summary"
 
-    async def on_GET(self, origin, content, query, group_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -972,7 +1145,13 @@ class FederationGroupsRoomsServlet(BaseGroupsServerServlet):
 
     PATH = "/groups/(?P<group_id>[^/]*)/rooms"
 
-    async def on_GET(self, origin, content, query, group_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -987,7 +1166,14 @@ class FederationGroupsAddRoomsServlet(BaseGroupsServerServlet):
 
     PATH = "/groups/(?P<group_id>[^/]*)/room/(?P<room_id>[^/]*)"
 
-    async def on_POST(self, origin, content, query, group_id, room_id):
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        room_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -998,7 +1184,14 @@ class FederationGroupsAddRoomsServlet(BaseGroupsServerServlet):
 
         return 200, new_content
 
-    async def on_DELETE(self, origin, content, query, group_id, room_id):
+    async def on_DELETE(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        room_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1018,7 +1211,15 @@ class FederationGroupsAddRoomsConfigServlet(BaseGroupsServerServlet):
         "/config/(?P<config_key>[^/]*)"
     )
 
-    async def on_POST(self, origin, content, query, group_id, room_id, config_key):
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        room_id: str,
+        config_key: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1035,7 +1236,13 @@ class FederationGroupsUsersServlet(BaseGroupsServerServlet):
 
     PATH = "/groups/(?P<group_id>[^/]*)/users"
 
-    async def on_GET(self, origin, content, query, group_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1050,7 +1257,13 @@ class FederationGroupsInvitedUsersServlet(BaseGroupsServerServlet):
 
     PATH = "/groups/(?P<group_id>[^/]*)/invited_users"
 
-    async def on_GET(self, origin, content, query, group_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1067,7 +1280,14 @@ class FederationGroupsInviteServlet(BaseGroupsServerServlet):
 
     PATH = "/groups/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/invite"
 
-    async def on_POST(self, origin, content, query, group_id, user_id):
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        user_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1084,7 +1304,14 @@ class FederationGroupsAcceptInviteServlet(BaseGroupsServerServlet):
 
     PATH = "/groups/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/accept_invite"
 
-    async def on_POST(self, origin, content, query, group_id, user_id):
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        user_id: str,
+    ) -> Tuple[int, JsonDict]:
         if get_domain_from_id(user_id) != origin:
             raise SynapseError(403, "user_id doesn't match origin")
 
@@ -1098,7 +1325,14 @@ class FederationGroupsJoinServlet(BaseGroupsServerServlet):
 
     PATH = "/groups/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/join"
 
-    async def on_POST(self, origin, content, query, group_id, user_id):
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        user_id: str,
+    ) -> Tuple[int, JsonDict]:
         if get_domain_from_id(user_id) != origin:
             raise SynapseError(403, "user_id doesn't match origin")
 
@@ -1112,7 +1346,14 @@ class FederationGroupsRemoveUserServlet(BaseGroupsServerServlet):
 
     PATH = "/groups/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/remove"
 
-    async def on_POST(self, origin, content, query, group_id, user_id):
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        user_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1146,7 +1387,14 @@ class FederationGroupsLocalInviteServlet(BaseGroupsLocalServlet):
 
     PATH = "/groups/local/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/invite"
 
-    async def on_POST(self, origin, content, query, group_id, user_id):
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        user_id: str,
+    ) -> Tuple[int, JsonDict]:
         if get_domain_from_id(group_id) != origin:
             raise SynapseError(403, "group_id doesn't match origin")
 
@@ -1164,7 +1412,14 @@ class FederationGroupsRemoveLocalUserServlet(BaseGroupsLocalServlet):
 
     PATH = "/groups/local/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/remove"
 
-    async def on_POST(self, origin, content, query, group_id, user_id):
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        user_id: str,
+    ) -> Tuple[int, None]:
         if get_domain_from_id(group_id) != origin:
             raise SynapseError(403, "user_id doesn't match origin")
 
@@ -1172,11 +1427,9 @@ class FederationGroupsRemoveLocalUserServlet(BaseGroupsLocalServlet):
             self.handler, GroupsLocalHandler
         ), "Workers cannot handle group removals."
 
-        new_content = await self.handler.user_removed_from_group(
-            group_id, user_id, content
-        )
+        await self.handler.user_removed_from_group(group_id, user_id, content)
 
-        return 200, new_content
+        return 200, None
 
 
 class FederationGroupsRenewAttestaionServlet(BaseFederationServlet):
@@ -1194,7 +1447,14 @@ class FederationGroupsRenewAttestaionServlet(BaseFederationServlet):
         super().__init__(hs, authenticator, ratelimiter, server_name)
         self.handler = hs.get_groups_attestation_renewer()
 
-    async def on_POST(self, origin, content, query, group_id, user_id):
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        user_id: str,
+    ) -> Tuple[int, JsonDict]:
         # We don't need to check auth here as we check the attestation signatures
 
         new_content = await self.handler.on_renew_attestation(
@@ -1218,7 +1478,15 @@ class FederationGroupsSummaryRoomsServlet(BaseGroupsServerServlet):
         "/rooms/(?P<room_id>[^/]*)"
     )
 
-    async def on_POST(self, origin, content, query, group_id, category_id, room_id):
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        category_id: str,
+        room_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1246,7 +1514,15 @@ class FederationGroupsSummaryRoomsServlet(BaseGroupsServerServlet):
 
         return 200, resp
 
-    async def on_DELETE(self, origin, content, query, group_id, category_id, room_id):
+    async def on_DELETE(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        category_id: str,
+        room_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1266,7 +1542,13 @@ class FederationGroupsCategoriesServlet(BaseGroupsServerServlet):
 
     PATH = "/groups/(?P<group_id>[^/]*)/categories/?"
 
-    async def on_GET(self, origin, content, query, group_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1281,7 +1563,14 @@ class FederationGroupsCategoryServlet(BaseGroupsServerServlet):
 
     PATH = "/groups/(?P<group_id>[^/]*)/categories/(?P<category_id>[^/]+)"
 
-    async def on_GET(self, origin, content, query, group_id, category_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        category_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1292,7 +1581,14 @@ class FederationGroupsCategoryServlet(BaseGroupsServerServlet):
 
         return 200, resp
 
-    async def on_POST(self, origin, content, query, group_id, category_id):
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        category_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1314,7 +1610,14 @@ class FederationGroupsCategoryServlet(BaseGroupsServerServlet):
 
         return 200, resp
 
-    async def on_DELETE(self, origin, content, query, group_id, category_id):
+    async def on_DELETE(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        category_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1334,7 +1637,13 @@ class FederationGroupsRolesServlet(BaseGroupsServerServlet):
 
     PATH = "/groups/(?P<group_id>[^/]*)/roles/?"
 
-    async def on_GET(self, origin, content, query, group_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1349,7 +1658,14 @@ class FederationGroupsRoleServlet(BaseGroupsServerServlet):
 
     PATH = "/groups/(?P<group_id>[^/]*)/roles/(?P<role_id>[^/]+)"
 
-    async def on_GET(self, origin, content, query, group_id, role_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        role_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1358,7 +1674,14 @@ class FederationGroupsRoleServlet(BaseGroupsServerServlet):
 
         return 200, resp
 
-    async def on_POST(self, origin, content, query, group_id, role_id):
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        role_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1382,7 +1705,14 @@ class FederationGroupsRoleServlet(BaseGroupsServerServlet):
 
         return 200, resp
 
-    async def on_DELETE(self, origin, content, query, group_id, role_id):
+    async def on_DELETE(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        role_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1411,7 +1741,15 @@ class FederationGroupsSummaryUsersServlet(BaseGroupsServerServlet):
         "/users/(?P<user_id>[^/]*)"
     )
 
-    async def on_POST(self, origin, content, query, group_id, role_id, user_id):
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        role_id: str,
+        user_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1437,7 +1775,15 @@ class FederationGroupsSummaryUsersServlet(BaseGroupsServerServlet):
 
         return 200, resp
 
-    async def on_DELETE(self, origin, content, query, group_id, role_id, user_id):
+    async def on_DELETE(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+        role_id: str,
+        user_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1457,7 +1803,9 @@ class FederationGroupsBulkPublicisedServlet(BaseGroupsLocalServlet):
 
     PATH = "/get_groups_publicised"
 
-    async def on_POST(self, origin, content, query):
+    async def on_POST(
+        self, origin: str, content: JsonDict, query: Dict[bytes, List[bytes]]
+    ) -> Tuple[int, JsonDict]:
         resp = await self.handler.bulk_get_publicised_groups(
             content["user_ids"], proxy=False
         )
@@ -1470,7 +1818,13 @@ class FederationGroupsSettingJoinPolicyServlet(BaseGroupsServerServlet):
 
     PATH = "/groups/(?P<group_id>[^/]*)/settings/m.join_policy"
 
-    async def on_PUT(self, origin, content, query, group_id):
+    async def on_PUT(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Dict[bytes, List[bytes]],
+        group_id: str,
+    ) -> Tuple[int, JsonDict]:
         requester_user_id = parse_string_from_args(query, "requester_user_id")
         if get_domain_from_id(requester_user_id) != origin:
             raise SynapseError(403, "requester_user_id doesn't match origin")
@@ -1499,7 +1853,7 @@ class FederationSpaceSummaryServlet(BaseFederationServlet):
     async def on_GET(
         self,
         origin: str,
-        content: JsonDict,
+        content: Literal[None],
         query: Mapping[bytes, Sequence[bytes]],
         room_id: str,
     ) -> Tuple[int, JsonDict]:
@@ -1571,7 +1925,13 @@ class RoomComplexityServlet(BaseFederationServlet):
         super().__init__(hs, authenticator, ratelimiter, server_name)
         self._store = self.hs.get_datastore()
 
-    async def on_GET(self, origin, content, query, room_id):
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Dict[bytes, List[bytes]],
+        room_id: str,
+    ) -> Tuple[int, JsonDict]:
         is_public = await self._store.is_room_world_readable_or_publicly_joinable(
             room_id
         )
diff --git a/synapse/http/servlet.py b/synapse/http/servlet.py
index fda8da21b7..6ba2ce1e53 100644
--- a/synapse/http/servlet.py
+++ b/synapse/http/servlet.py
@@ -113,8 +113,18 @@ def parse_boolean_from_args(args, name, default=None, required=False):
 def parse_bytes_from_args(
     args: Dict[bytes, List[bytes]],
     name: str,
+    default: Optional[bytes] = None,
+) -> Optional[bytes]:
+    ...
+
+
+@overload
+def parse_bytes_from_args(
+    args: Dict[bytes, List[bytes]],
+    name: str,
     default: Literal[None] = None,
-    required: Literal[True] = True,
+    *,
+    required: Literal[True],
 ) -> bytes:
     ...
 
@@ -197,7 +207,12 @@ def parse_string(
     """
     args = request.args  # type: Dict[bytes, List[bytes]]  # type: ignore
     return parse_string_from_args(
-        args, name, default, required, allowed_values, encoding
+        args,
+        name,
+        default,
+        required=required,
+        allowed_values=allowed_values,
+        encoding=encoding,
     )
 
 
@@ -227,7 +242,20 @@ def parse_strings_from_args(
     args: Dict[bytes, List[bytes]],
     name: str,
     default: Optional[List[str]] = None,
-    required: Literal[True] = True,
+    *,
+    allowed_values: Optional[Iterable[str]] = None,
+    encoding: str = "ascii",
+) -> Optional[List[str]]:
+    ...
+
+
+@overload
+def parse_strings_from_args(
+    args: Dict[bytes, List[bytes]],
+    name: str,
+    default: Optional[List[str]] = None,
+    *,
+    required: Literal[True],
     allowed_values: Optional[Iterable[str]] = None,
     encoding: str = "ascii",
 ) -> List[str]:
@@ -239,6 +267,7 @@ def parse_strings_from_args(
     args: Dict[bytes, List[bytes]],
     name: str,
     default: Optional[List[str]] = None,
+    *,
     required: bool = False,
     allowed_values: Optional[Iterable[str]] = None,
     encoding: str = "ascii",
@@ -299,7 +328,20 @@ def parse_string_from_args(
     args: Dict[bytes, List[bytes]],
     name: str,
     default: Optional[str] = None,
-    required: Literal[True] = True,
+    *,
+    allowed_values: Optional[Iterable[str]] = None,
+    encoding: str = "ascii",
+) -> Optional[str]:
+    ...
+
+
+@overload
+def parse_string_from_args(
+    args: Dict[bytes, List[bytes]],
+    name: str,
+    default: Optional[str] = None,
+    *,
+    required: Literal[True],
     allowed_values: Optional[Iterable[str]] = None,
     encoding: str = "ascii",
 ) -> str: