Additional type hints for REST servlets (part 2). (#10674)

Applies the changes from #10665 to additional modules.

16 files changed, 215 insertions, 138 deletions

diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py
index 7ca14e1d84..4418d63df7 100644
--- a/synapse/handlers/presence.py
+++ b/synapse/handlers/presence.py
@@ -353,6 +353,11 @@ class BasePresenceHandler(abc.ABC):
         # otherwise would not do).
         await self.set_state(UserID.from_string(user_id), state, force_notify=True)
 
+    async def is_visible(self, observed_user: UserID, observer_user: UserID) -> bool:
+        raise NotImplementedError(
+            "Attempting to check presence on a non-presence worker."
+        )
+
 
 class _NullContextManager(ContextManager[None]):
     """A context manager which does nothing."""
diff --git a/synapse/rest/client/auth.py b/synapse/rest/client/auth.py
index 91800c0278..df8cc4ac7a 100644
--- a/synapse/rest/client/auth.py
+++ b/synapse/rest/client/auth.py
@@ -15,11 +15,14 @@
 import logging
 from typing import TYPE_CHECKING
 
+from twisted.web.server import Request
+
 from synapse.api.constants import LoginType
 from synapse.api.errors import LoginError, SynapseError
 from synapse.api.urls import CLIENT_API_PREFIX
-from synapse.http.server import respond_with_html
+from synapse.http.server import HttpServer, respond_with_html
 from synapse.http.servlet import RestServlet, parse_string
+from synapse.http.site import SynapseRequest
 
 from ._base import client_patterns
 
@@ -49,7 +52,7 @@ class AuthRestServlet(RestServlet):
         self.registration_token_template = hs.config.registration_token_template
         self.success_template = hs.config.fallback_success_template
 
-    async def on_GET(self, request, stagetype):
+    async def on_GET(self, request: SynapseRequest, stagetype: str) -> None:
         session = parse_string(request, "session")
         if not session:
             raise SynapseError(400, "No session supplied")
@@ -88,7 +91,7 @@ class AuthRestServlet(RestServlet):
         respond_with_html(request, 200, html)
         return None
 
-    async def on_POST(self, request, stagetype):
+    async def on_POST(self, request: Request, stagetype: str) -> None:
 
         session = parse_string(request, "session")
         if not session:
@@ -172,5 +175,5 @@ class AuthRestServlet(RestServlet):
         return None
 
 
-def register_servlets(hs, http_server):
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     AuthRestServlet(hs).register(http_server)
diff --git a/synapse/rest/client/devices.py b/synapse/rest/client/devices.py
index 8b9674db06..25bc3c8f47 100644
--- a/synapse/rest/client/devices.py
+++ b/synapse/rest/client/devices.py
@@ -14,34 +14,36 @@
 # limitations under the License.
 
 import logging
+from typing import TYPE_CHECKING, Tuple
 
 from synapse.api import errors
+from synapse.http.server import HttpServer
 from synapse.http.servlet import (
     RestServlet,
     assert_params_in_dict,
     parse_json_object_from_request,
 )
 from synapse.http.site import SynapseRequest
+from synapse.types import JsonDict
 
 from ._base import client_patterns, interactive_auth_handler
 
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+
 logger = logging.getLogger(__name__)
 
 
 class DevicesRestServlet(RestServlet):
     PATTERNS = client_patterns("/devices$")
 
-    def __init__(self, hs):
-        """
-        Args:
-            hs (synapse.server.HomeServer): server
-        """
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.hs = hs
         self.auth = hs.get_auth()
         self.device_handler = hs.get_device_handler()
 
-    async def on_GET(self, request):
+    async def on_GET(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request, allow_guest=True)
         devices = await self.device_handler.get_devices_by_user(
             requester.user.to_string()
@@ -57,7 +59,7 @@ class DeleteDevicesRestServlet(RestServlet):
 
     PATTERNS = client_patterns("/delete_devices")
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.hs = hs
         self.auth = hs.get_auth()
@@ -65,7 +67,7 @@ class DeleteDevicesRestServlet(RestServlet):
         self.auth_handler = hs.get_auth_handler()
 
     @interactive_auth_handler
-    async def on_POST(self, request):
+    async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request)
 
         try:
@@ -100,18 +102,16 @@ class DeleteDevicesRestServlet(RestServlet):
 class DeviceRestServlet(RestServlet):
     PATTERNS = client_patterns("/devices/(?P<device_id>[^/]*)$")
 
-    def __init__(self, hs):
-        """
-        Args:
-            hs (synapse.server.HomeServer): server
-        """
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.hs = hs
         self.auth = hs.get_auth()
         self.device_handler = hs.get_device_handler()
         self.auth_handler = hs.get_auth_handler()
 
-    async def on_GET(self, request, device_id):
+    async def on_GET(
+        self, request: SynapseRequest, device_id: str
+    ) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request, allow_guest=True)
         device = await self.device_handler.get_device(
             requester.user.to_string(), device_id
@@ -119,7 +119,9 @@ class DeviceRestServlet(RestServlet):
         return 200, device
 
     @interactive_auth_handler
-    async def on_DELETE(self, request, device_id):
+    async def on_DELETE(
+        self, request: SynapseRequest, device_id: str
+    ) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request)
 
         try:
@@ -146,7 +148,9 @@ class DeviceRestServlet(RestServlet):
         await self.device_handler.delete_device(requester.user.to_string(), device_id)
         return 200, {}
 
-    async def on_PUT(self, request, device_id):
+    async def on_PUT(
+        self, request: SynapseRequest, device_id: str
+    ) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request, allow_guest=True)
 
         body = parse_json_object_from_request(request)
@@ -193,13 +197,13 @@ class DehydratedDeviceServlet(RestServlet):
 
     PATTERNS = client_patterns("/org.matrix.msc2697.v2/dehydrated_device", releases=())
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.hs = hs
         self.auth = hs.get_auth()
         self.device_handler = hs.get_device_handler()
 
-    async def on_GET(self, request: SynapseRequest):
+    async def on_GET(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request)
         dehydrated_device = await self.device_handler.get_dehydrated_device(
             requester.user.to_string()
@@ -211,7 +215,7 @@ class DehydratedDeviceServlet(RestServlet):
         else:
             raise errors.NotFoundError("No dehydrated device available")
 
-    async def on_PUT(self, request: SynapseRequest):
+    async def on_PUT(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         submission = parse_json_object_from_request(request)
         requester = await self.auth.get_user_by_req(request)
 
@@ -259,13 +263,13 @@ class ClaimDehydratedDeviceServlet(RestServlet):
         "/org.matrix.msc2697.v2/dehydrated_device/claim", releases=()
     )
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.hs = hs
         self.auth = hs.get_auth()
         self.device_handler = hs.get_device_handler()
 
-    async def on_POST(self, request: SynapseRequest):
+    async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request)
 
         submission = parse_json_object_from_request(request)
@@ -292,7 +296,7 @@ class ClaimDehydratedDeviceServlet(RestServlet):
         return (200, result)
 
 
-def register_servlets(hs, http_server):
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     DeleteDevicesRestServlet(hs).register(http_server)
     DevicesRestServlet(hs).register(http_server)
     DeviceRestServlet(hs).register(http_server)
diff --git a/synapse/rest/client/events.py b/synapse/rest/client/events.py
index 52bb579cfd..13b72a045a 100644
--- a/synapse/rest/client/events.py
+++ b/synapse/rest/client/events.py
@@ -14,11 +14,18 @@
 
 """This module contains REST servlets to do with event streaming, /events."""
 import logging
+from typing import TYPE_CHECKING, Dict, List, Tuple, Union
 
 from synapse.api.errors import SynapseError
-from synapse.http.servlet import RestServlet
+from synapse.http.server import HttpServer
+from synapse.http.servlet import RestServlet, parse_string
+from synapse.http.site import SynapseRequest
 from synapse.rest.client._base import client_patterns
 from synapse.streams.config import PaginationConfig
+from synapse.types import JsonDict
+
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
 
 logger = logging.getLogger(__name__)
 
@@ -28,31 +35,30 @@ class EventStreamRestServlet(RestServlet):
 
     DEFAULT_LONGPOLL_TIME_MS = 30000
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.event_stream_handler = hs.get_event_stream_handler()
         self.auth = hs.get_auth()
         self.store = hs.get_datastore()
 
-    async def on_GET(self, request):
+    async def on_GET(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request, allow_guest=True)
         is_guest = requester.is_guest
-        room_id = None
+        args: Dict[bytes, List[bytes]] = request.args  # type: ignore
         if is_guest:
-            if b"room_id" not in request.args:
+            if b"room_id" not in args:
                 raise SynapseError(400, "Guest users must specify room_id param")
-        if b"room_id" in request.args:
-            room_id = request.args[b"room_id"][0].decode("ascii")
+        room_id = parse_string(request, "room_id")
 
         pagin_config = await PaginationConfig.from_request(self.store, request)
         timeout = EventStreamRestServlet.DEFAULT_LONGPOLL_TIME_MS
-        if b"timeout" in request.args:
+        if b"timeout" in args:
             try:
-                timeout = int(request.args[b"timeout"][0])
+                timeout = int(args[b"timeout"][0])
             except ValueError:
                 raise SynapseError(400, "timeout must be in milliseconds.")
 
-        as_client_event = b"raw" not in request.args
+        as_client_event = b"raw" not in args
 
         chunk = await self.event_stream_handler.get_stream(
             requester.user.to_string(),
@@ -70,25 +76,27 @@ class EventStreamRestServlet(RestServlet):
 class EventRestServlet(RestServlet):
     PATTERNS = client_patterns("/events/(?P<event_id>[^/]*)$", v1=True)
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.clock = hs.get_clock()
         self.event_handler = hs.get_event_handler()
         self.auth = hs.get_auth()
         self._event_serializer = hs.get_event_client_serializer()
 
-    async def on_GET(self, request, event_id):
+    async def on_GET(
+        self, request: SynapseRequest, event_id: str
+    ) -> Tuple[int, Union[str, JsonDict]]:
         requester = await self.auth.get_user_by_req(request)
         event = await self.event_handler.get_event(requester.user, None, event_id)
 
         time_now = self.clock.time_msec()
         if event:
-            event = await self._event_serializer.serialize_event(event, time_now)
-            return 200, event
+            result = await self._event_serializer.serialize_event(event, time_now)
+            return 200, result
         else:
             return 404, "Event not found."
 
 
-def register_servlets(hs, http_server):
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     EventStreamRestServlet(hs).register(http_server)
     EventRestServlet(hs).register(http_server)
diff --git a/synapse/rest/client/filter.py b/synapse/rest/client/filter.py
index 411667a9c8..6ed60c7418 100644
--- a/synapse/rest/client/filter.py
+++ b/synapse/rest/client/filter.py
@@ -13,26 +13,34 @@
 # limitations under the License.
 
 import logging
+from typing import TYPE_CHECKING, Tuple
 
 from synapse.api.errors import AuthError, NotFoundError, StoreError, SynapseError
+from synapse.http.server import HttpServer
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
-from synapse.types import UserID
+from synapse.http.site import SynapseRequest
+from synapse.types import JsonDict, UserID
 
 from ._base import client_patterns, set_timeline_upper_limit
 
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+
 logger = logging.getLogger(__name__)
 
 
 class GetFilterRestServlet(RestServlet):
     PATTERNS = client_patterns("/user/(?P<user_id>[^/]*)/filter/(?P<filter_id>[^/]*)")
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.hs = hs
         self.auth = hs.get_auth()
         self.filtering = hs.get_filtering()
 
-    async def on_GET(self, request, user_id, filter_id):
+    async def on_GET(
+        self, request: SynapseRequest, user_id: str, filter_id: str
+    ) -> Tuple[int, JsonDict]:
         target_user = UserID.from_string(user_id)
         requester = await self.auth.get_user_by_req(request)
 
@@ -43,13 +51,13 @@ class GetFilterRestServlet(RestServlet):
             raise AuthError(403, "Can only get filters for local users")
 
         try:
-            filter_id = int(filter_id)
+            filter_id_int = int(filter_id)
         except Exception:
             raise SynapseError(400, "Invalid filter_id")
 
         try:
             filter_collection = await self.filtering.get_user_filter(
-                user_localpart=target_user.localpart, filter_id=filter_id
+                user_localpart=target_user.localpart, filter_id=filter_id_int
             )
         except StoreError as e:
             if e.code != 404:
@@ -62,13 +70,15 @@ class GetFilterRestServlet(RestServlet):
 class CreateFilterRestServlet(RestServlet):
     PATTERNS = client_patterns("/user/(?P<user_id>[^/]*)/filter")
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.hs = hs
         self.auth = hs.get_auth()
         self.filtering = hs.get_filtering()
 
-    async def on_POST(self, request, user_id):
+    async def on_POST(
+        self, request: SynapseRequest, user_id: str
+    ) -> Tuple[int, JsonDict]:
 
         target_user = UserID.from_string(user_id)
         requester = await self.auth.get_user_by_req(request)
@@ -89,6 +99,6 @@ class CreateFilterRestServlet(RestServlet):
         return 200, {"filter_id": str(filter_id)}
 
 
-def register_servlets(hs, http_server):
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     GetFilterRestServlet(hs).register(http_server)
     CreateFilterRestServlet(hs).register(http_server)
diff --git a/synapse/rest/client/groups.py b/synapse/rest/client/groups.py
index 6285680c00..c3667ff8aa 100644
--- a/synapse/rest/client/groups.py
+++ b/synapse/rest/client/groups.py
@@ -26,6 +26,7 @@ from synapse.api.constants import (
 )
 from synapse.api.errors import Codes, SynapseError
 from synapse.handlers.groups_local import GroupsLocalHandler
+from synapse.http.server import HttpServer
 from synapse.http.servlet import (
     RestServlet,
     assert_params_in_dict,
@@ -930,7 +931,7 @@ class GroupsForUserServlet(RestServlet):
         return 200, result
 
 
-def register_servlets(hs: "HomeServer", http_server):
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     GroupServlet(hs).register(http_server)
     GroupSummaryServlet(hs).register(http_server)
     GroupInvitedUsersServlet(hs).register(http_server)
diff --git a/synapse/rest/client/initial_sync.py b/synapse/rest/client/initial_sync.py
index 12ba0e91db..49b1037b28 100644
--- a/synapse/rest/client/initial_sync.py
+++ b/synapse/rest/client/initial_sync.py
@@ -12,25 +12,33 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from typing import TYPE_CHECKING, Dict, List, Tuple
 
+from synapse.http.server import HttpServer
 from synapse.http.servlet import RestServlet, parse_boolean
+from synapse.http.site import SynapseRequest
 from synapse.rest.client._base import client_patterns
 from synapse.streams.config import PaginationConfig
+from synapse.types import JsonDict
+
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
 
 
 # TODO: Needs unit testing
 class InitialSyncRestServlet(RestServlet):
     PATTERNS = client_patterns("/initialSync$", v1=True)
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.initial_sync_handler = hs.get_initial_sync_handler()
         self.auth = hs.get_auth()
         self.store = hs.get_datastore()
 
-    async def on_GET(self, request):
+    async def on_GET(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request)
-        as_client_event = b"raw" not in request.args
+        args: Dict[bytes, List[bytes]] = request.args  # type: ignore
+        as_client_event = b"raw" not in args
         pagination_config = await PaginationConfig.from_request(self.store, request)
         include_archived = parse_boolean(request, "archived", default=False)
         content = await self.initial_sync_handler.snapshot_all_rooms(
@@ -43,5 +51,5 @@ class InitialSyncRestServlet(RestServlet):
         return 200, content
 
 
-def register_servlets(hs, http_server):
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     InitialSyncRestServlet(hs).register(http_server)
diff --git a/synapse/rest/client/keys.py b/synapse/rest/client/keys.py
index 012491f597..7281b2ee29 100644
--- a/synapse/rest/client/keys.py
+++ b/synapse/rest/client/keys.py
@@ -15,20 +15,25 @@
 # limitations under the License.
 
 import logging
-from typing import Any
+from typing import TYPE_CHECKING, Any, Optional, Tuple
 
 from synapse.api.errors import InvalidAPICallError, SynapseError
+from synapse.http.server import HttpServer
 from synapse.http.servlet import (
     RestServlet,
     parse_integer,
     parse_json_object_from_request,
     parse_string,
 )
+from synapse.http.site import SynapseRequest
 from synapse.logging.opentracing import log_kv, set_tag, trace
-from synapse.types import StreamToken
+from synapse.types import JsonDict, StreamToken
 
 from ._base import client_patterns, interactive_auth_handler
 
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+
 logger = logging.getLogger(__name__)
 
 
@@ -60,18 +65,16 @@ class KeyUploadServlet(RestServlet):
 
     PATTERNS = client_patterns("/keys/upload(/(?P<device_id>[^/]+))?$")
 
-    def __init__(self, hs):
-        """
-        Args:
-            hs (synapse.server.HomeServer): server
-        """
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.auth = hs.get_auth()
         self.e2e_keys_handler = hs.get_e2e_keys_handler()
         self.device_handler = hs.get_device_handler()
 
     @trace(opname="upload_keys")
-    async def on_POST(self, request, device_id):
+    async def on_POST(
+        self, request: SynapseRequest, device_id: Optional[str]
+    ) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request, allow_guest=True)
         user_id = requester.user.to_string()
         body = parse_json_object_from_request(request)
@@ -149,16 +152,12 @@ class KeyQueryServlet(RestServlet):
 
     PATTERNS = client_patterns("/keys/query$")
 
-    def __init__(self, hs):
-        """
-        Args:
-            hs (synapse.server.HomeServer):
-        """
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.auth = hs.get_auth()
         self.e2e_keys_handler = hs.get_e2e_keys_handler()
 
-    async def on_POST(self, request):
+    async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request, allow_guest=True)
         user_id = requester.user.to_string()
         device_id = requester.device_id
@@ -195,17 +194,13 @@ class KeyChangesServlet(RestServlet):
 
     PATTERNS = client_patterns("/keys/changes$")
 
-    def __init__(self, hs):
-        """
-        Args:
-            hs (synapse.server.HomeServer):
-        """
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.auth = hs.get_auth()
         self.device_handler = hs.get_device_handler()
         self.store = hs.get_datastore()
 
-    async def on_GET(self, request):
+    async def on_GET(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request, allow_guest=True)
 
         from_token_string = parse_string(request, "from", required=True)
@@ -245,12 +240,12 @@ class OneTimeKeyServlet(RestServlet):
 
     PATTERNS = client_patterns("/keys/claim$")
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.auth = hs.get_auth()
         self.e2e_keys_handler = hs.get_e2e_keys_handler()
 
-    async def on_POST(self, request):
+    async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         await self.auth.get_user_by_req(request, allow_guest=True)
         timeout = parse_integer(request, "timeout", 10 * 1000)
         body = parse_json_object_from_request(request)
@@ -269,11 +264,7 @@ class SigningKeyUploadServlet(RestServlet):
 
     PATTERNS = client_patterns("/keys/device_signing/upload$", releases=())
 
-    def __init__(self, hs):
-        """
-        Args:
-            hs (synapse.server.HomeServer): server
-        """
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.hs = hs
         self.auth = hs.get_auth()
@@ -281,7 +272,7 @@ class SigningKeyUploadServlet(RestServlet):
         self.auth_handler = hs.get_auth_handler()
 
     @interactive_auth_handler
-    async def on_POST(self, request):
+    async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request)
         user_id = requester.user.to_string()
         body = parse_json_object_from_request(request)
@@ -329,16 +320,12 @@ class SignaturesUploadServlet(RestServlet):
 
     PATTERNS = client_patterns("/keys/signatures/upload$")
 
-    def __init__(self, hs):
-        """
-        Args:
-            hs (synapse.server.HomeServer): server
-        """
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.auth = hs.get_auth()
         self.e2e_keys_handler = hs.get_e2e_keys_handler()
 
-    async def on_POST(self, request):
+    async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request, allow_guest=True)
         user_id = requester.user.to_string()
         body = parse_json_object_from_request(request)
@@ -349,7 +336,7 @@ class SignaturesUploadServlet(RestServlet):
         return 200, result
 
 
-def register_servlets(hs, http_server):
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     KeyUploadServlet(hs).register(http_server)
     KeyQueryServlet(hs).register(http_server)
     KeyChangesServlet(hs).register(http_server)
diff --git a/synapse/rest/client/knock.py b/synapse/rest/client/knock.py
index 7d1bc40658..68fb08d0ba 100644
--- a/synapse/rest/client/knock.py
+++ b/synapse/rest/client/knock.py
@@ -19,6 +19,7 @@ from twisted.web.server import Request
 
 from synapse.api.constants import Membership
 from synapse.api.errors import SynapseError
+from synapse.http.server import HttpServer
 from synapse.http.servlet import (
     RestServlet,
     parse_json_object_from_request,
@@ -103,5 +104,5 @@ class KnockRoomAliasServlet(RestServlet):
         )
 
 
-def register_servlets(hs, http_server):
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     KnockRoomAliasServlet(hs).register(http_server)
diff --git a/synapse/rest/client/login.py b/synapse/rest/client/login.py
index 11d07776b2..4be502a77b 100644
--- a/synapse/rest/client/login.py
+++ b/synapse/rest/client/login.py
@@ -1,4 +1,4 @@
-# Copyright 2014-2016 OpenMarket Ltd
+# Copyright 2014-2021 The Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -14,7 +14,7 @@
 
 import logging
 import re
-from typing import TYPE_CHECKING, Any, Awaitable, Callable, Dict, List, Optional
+from typing import TYPE_CHECKING, Any, Awaitable, Callable, Dict, List, Optional, Tuple
 
 from typing_extensions import TypedDict
 
@@ -110,7 +110,7 @@ class LoginRestServlet(RestServlet):
         # counters are initialised for the auth_provider_ids.
         _load_sso_handlers(hs)
 
-    def on_GET(self, request: SynapseRequest):
+    def on_GET(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         flows = []
         if self.jwt_enabled:
             flows.append({"type": LoginRestServlet.JWT_TYPE})
@@ -157,7 +157,7 @@ class LoginRestServlet(RestServlet):
 
         return 200, {"flows": flows}
 
-    async def on_POST(self, request: SynapseRequest):
+    async def on_POST(self, request: SynapseRequest) -> Tuple[int, LoginResponse]:
         login_submission = parse_json_object_from_request(request)
 
         if self._msc2918_enabled:
@@ -217,7 +217,7 @@ class LoginRestServlet(RestServlet):
         login_submission: JsonDict,
         appservice: ApplicationService,
         should_issue_refresh_token: bool = False,
-    ):
+    ) -> LoginResponse:
         identifier = login_submission.get("identifier")
         logger.info("Got appservice login request with identifier: %r", identifier)
 
@@ -467,10 +467,7 @@ class RefreshTokenServlet(RestServlet):
         self._clock = hs.get_clock()
         self.access_token_lifetime = hs.config.access_token_lifetime
 
-    async def on_POST(
-        self,
-        request: SynapseRequest,
-    ):
+    async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         refresh_submission = parse_json_object_from_request(request)
 
         assert_params_in_dict(refresh_submission, ["refresh_token"])
@@ -570,7 +567,7 @@ class SsoRedirectServlet(RestServlet):
 class CasTicketServlet(RestServlet):
     PATTERNS = client_patterns("/login/cas/ticket", v1=True)
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self._cas_handler = hs.get_cas_handler()
 
@@ -592,7 +589,7 @@ class CasTicketServlet(RestServlet):
         )
 
 
-def register_servlets(hs, http_server):
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     LoginRestServlet(hs).register(http_server)
     if hs.config.access_token_lifetime is not None:
         RefreshTokenServlet(hs).register(http_server)
@@ -601,7 +598,7 @@ def register_servlets(hs, http_server):
         CasTicketServlet(hs).register(http_server)
 
 
-def _load_sso_handlers(hs: "HomeServer"):
+def _load_sso_handlers(hs: "HomeServer") -> None:
     """Ensure that the SSO handlers are loaded, if they are enabled by configuration.
 
     This is mostly useful to ensure that the CAS/SAML/OIDC handlers register themselves
diff --git a/synapse/rest/client/logout.py b/synapse/rest/client/logout.py
index 6055cac2bd..193a6951b9 100644
--- a/synapse/rest/client/logout.py
+++ b/synapse/rest/client/logout.py
@@ -13,9 +13,16 @@
 # limitations under the License.
 
 import logging
+from typing import TYPE_CHECKING, Tuple
 
+from synapse.http.server import HttpServer
 from synapse.http.servlet import RestServlet
+from synapse.http.site import SynapseRequest
 from synapse.rest.client._base import client_patterns
+from synapse.types import JsonDict
+
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
 
 logger = logging.getLogger(__name__)
 
@@ -23,13 +30,13 @@ logger = logging.getLogger(__name__)
 class LogoutRestServlet(RestServlet):
     PATTERNS = client_patterns("/logout$", v1=True)
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.auth = hs.get_auth()
         self._auth_handler = hs.get_auth_handler()
         self._device_handler = hs.get_device_handler()
 
-    async def on_POST(self, request):
+    async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request, allow_expired=True)
 
         if requester.device_id is None:
@@ -48,13 +55,13 @@ class LogoutRestServlet(RestServlet):
 class LogoutAllRestServlet(RestServlet):
     PATTERNS = client_patterns("/logout/all$", v1=True)
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.auth = hs.get_auth()
         self._auth_handler = hs.get_auth_handler()
         self._device_handler = hs.get_device_handler()
 
-    async def on_POST(self, request):
+    async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request, allow_expired=True)
         user_id = requester.user.to_string()
 
@@ -67,6 +74,6 @@ class LogoutAllRestServlet(RestServlet):
         return 200, {}
 
 
-def register_servlets(hs, http_server):
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     LogoutRestServlet(hs).register(http_server)
     LogoutAllRestServlet(hs).register(http_server)
diff --git a/synapse/rest/client/notifications.py b/synapse/rest/client/notifications.py
index 0ede643c2d..d1d8a984c6 100644
--- a/synapse/rest/client/notifications.py
+++ b/synapse/rest/client/notifications.py
@@ -13,26 +13,33 @@
 # limitations under the License.
 
 import logging
+from typing import TYPE_CHECKING, Tuple
 
 from synapse.events.utils import format_event_for_client_v2_without_room_id
+from synapse.http.server import HttpServer
 from synapse.http.servlet import RestServlet, parse_integer, parse_string
+from synapse.http.site import SynapseRequest
+from synapse.types import JsonDict
 
 from ._base import client_patterns
 
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+
 logger = logging.getLogger(__name__)
 
 
 class NotificationsServlet(RestServlet):
     PATTERNS = client_patterns("/notifications$")
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.store = hs.get_datastore()
         self.auth = hs.get_auth()
         self.clock = hs.get_clock()
         self._event_serializer = hs.get_event_client_serializer()
 
-    async def on_GET(self, request):
+    async def on_GET(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request)
         user_id = requester.user.to_string()
 
@@ -87,5 +94,5 @@ class NotificationsServlet(RestServlet):
         return 200, {"notifications": returned_push_actions, "next_token": next_token}
 
 
-def register_servlets(hs, http_server):
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     NotificationsServlet(hs).register(http_server)
diff --git a/synapse/rest/client/openid.py b/synapse/rest/client/openid.py
index e8d2673819..4dda6dce4b 100644
--- a/synapse/rest/client/openid.py
+++ b/synapse/rest/client/openid.py
@@ -12,15 +12,21 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-
 import logging
+from typing import TYPE_CHECKING, Tuple
 
 from synapse.api.errors import AuthError
+from synapse.http.server import HttpServer
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
+from synapse.http.site import SynapseRequest
+from synapse.types import JsonDict
 from synapse.util.stringutils import random_string
 
 from ._base import client_patterns
 
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+
 logger = logging.getLogger(__name__)
 
 
@@ -58,14 +64,16 @@ class IdTokenServlet(RestServlet):
 
     EXPIRES_MS = 3600 * 1000
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.auth = hs.get_auth()
         self.store = hs.get_datastore()
         self.clock = hs.get_clock()
         self.server_name = hs.config.server_name
 
-    async def on_POST(self, request, user_id):
+    async def on_POST(
+        self, request: SynapseRequest, user_id: str
+    ) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request)
         if user_id != requester.user.to_string():
             raise AuthError(403, "Cannot request tokens for other users.")
@@ -90,5 +98,5 @@ class IdTokenServlet(RestServlet):
         )
 
 
-def register_servlets(hs, http_server):
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     IdTokenServlet(hs).register(http_server)
diff --git a/synapse/rest/client/password_policy.py b/synapse/rest/client/password_policy.py
index a83927aee6..6d64efb165 100644
--- a/synapse/rest/client/password_policy.py
+++ b/synapse/rest/client/password_policy.py
@@ -13,28 +13,32 @@
 # limitations under the License.
 
 import logging
+from typing import TYPE_CHECKING, Tuple
 
+from twisted.web.server import Request
+
+from synapse.http.server import HttpServer
 from synapse.http.servlet import RestServlet
+from synapse.types import JsonDict
 
 from ._base import client_patterns
 
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+
 logger = logging.getLogger(__name__)
 
 
 class PasswordPolicyServlet(RestServlet):
     PATTERNS = client_patterns("/password_policy$")
 
-    def __init__(self, hs):
-        """
-        Args:
-            hs (synapse.server.HomeServer): server
-        """
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
 
         self.policy = hs.config.password_policy
         self.enabled = hs.config.password_policy_enabled
 
-    def on_GET(self, request):
+    def on_GET(self, request: Request) -> Tuple[int, JsonDict]:
         if not self.enabled or not self.policy:
             return (200, {})
 
@@ -53,5 +57,5 @@ class PasswordPolicyServlet(RestServlet):
         return (200, policy)
 
 
-def register_servlets(hs, http_server):
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     PasswordPolicyServlet(hs).register(http_server)
diff --git a/synapse/rest/client/presence.py b/synapse/rest/client/presence.py
index 6c27e5faf9..94dd4fe2f4 100644
--- a/synapse/rest/client/presence.py
+++ b/synapse/rest/client/presence.py
@@ -15,12 +15,18 @@
 """ This module contains REST servlets to do with presence: /presence/<paths>
 """
 import logging
+from typing import TYPE_CHECKING, Tuple
 
 from synapse.api.errors import AuthError, SynapseError
 from synapse.handlers.presence import format_user_presence_state
+from synapse.http.server import HttpServer
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
+from synapse.http.site import SynapseRequest
 from synapse.rest.client._base import client_patterns
-from synapse.types import UserID
+from synapse.types import JsonDict, UserID
+
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
 
 logger = logging.getLogger(__name__)
 
@@ -28,7 +34,7 @@ logger = logging.getLogger(__name__)
 class PresenceStatusRestServlet(RestServlet):
     PATTERNS = client_patterns("/presence/(?P<user_id>[^/]*)/status", v1=True)
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.hs = hs
         self.presence_handler = hs.get_presence_handler()
@@ -37,7 +43,9 @@ class PresenceStatusRestServlet(RestServlet):
 
         self._use_presence = hs.config.server.use_presence
 
-    async def on_GET(self, request, user_id):
+    async def on_GET(
+        self, request: SynapseRequest, user_id: str
+    ) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request)
         user = UserID.from_string(user_id)
 
@@ -53,13 +61,15 @@ class PresenceStatusRestServlet(RestServlet):
                 raise AuthError(403, "You are not allowed to see their presence.")
 
         state = await self.presence_handler.get_state(target_user=user)
-        state = format_user_presence_state(
+        result = format_user_presence_state(
             state, self.clock.time_msec(), include_user_id=False
         )
 
-        return 200, state
+        return 200, result
 
-    async def on_PUT(self, request, user_id):
+    async def on_PUT(
+        self, request: SynapseRequest, user_id: str
+    ) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request)
         user = UserID.from_string(user_id)
 
@@ -91,5 +101,5 @@ class PresenceStatusRestServlet(RestServlet):
         return 200, {}
 
 
-def register_servlets(hs, http_server):
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     PresenceStatusRestServlet(hs).register(http_server)
diff --git a/synapse/rest/client/profile.py b/synapse/rest/client/profile.py
index 5463ed2c4f..d0f20de569 100644
--- a/synapse/rest/client/profile.py
+++ b/synapse/rest/client/profile.py
@@ -14,22 +14,31 @@
 
 """ This module contains REST servlets to do with profile: /profile/<paths> """
 
+from typing import TYPE_CHECKING, Tuple
+
 from synapse.api.errors import Codes, SynapseError
+from synapse.http.server import HttpServer
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
+from synapse.http.site import SynapseRequest
 from synapse.rest.client._base import client_patterns
-from synapse.types import UserID
+from synapse.types import JsonDict, UserID
+
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
 
 
 class ProfileDisplaynameRestServlet(RestServlet):
     PATTERNS = client_patterns("/profile/(?P<user_id>[^/]*)/displayname", v1=True)
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.hs = hs
         self.profile_handler = hs.get_profile_handler()
         self.auth = hs.get_auth()
 
-    async def on_GET(self, request, user_id):
+    async def on_GET(
+        self, request: SynapseRequest, user_id: str
+    ) -> Tuple[int, JsonDict]:
         requester_user = None
 
         if self.hs.config.require_auth_for_profile_requests:
@@ -48,7 +57,9 @@ class ProfileDisplaynameRestServlet(RestServlet):
 
         return 200, ret
 
-    async def on_PUT(self, request, user_id):
+    async def on_PUT(
+        self, request: SynapseRequest, user_id: str
+    ) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request, allow_guest=True)
         user = UserID.from_string(user_id)
         is_admin = await self.auth.is_server_admin(requester.user)
@@ -72,13 +83,15 @@ class ProfileDisplaynameRestServlet(RestServlet):
 class ProfileAvatarURLRestServlet(RestServlet):
     PATTERNS = client_patterns("/profile/(?P<user_id>[^/]*)/avatar_url", v1=True)
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.hs = hs
         self.profile_handler = hs.get_profile_handler()
         self.auth = hs.get_auth()
 
-    async def on_GET(self, request, user_id):
+    async def on_GET(
+        self, request: SynapseRequest, user_id: str
+    ) -> Tuple[int, JsonDict]:
         requester_user = None
 
         if self.hs.config.require_auth_for_profile_requests:
@@ -97,7 +110,9 @@ class ProfileAvatarURLRestServlet(RestServlet):
 
         return 200, ret
 
-    async def on_PUT(self, request, user_id):
+    async def on_PUT(
+        self, request: SynapseRequest, user_id: str
+    ) -> Tuple[int, JsonDict]:
         requester = await self.auth.get_user_by_req(request)
         user = UserID.from_string(user_id)
         is_admin = await self.auth.is_server_admin(requester.user)
@@ -120,13 +135,15 @@ class ProfileAvatarURLRestServlet(RestServlet):
 class ProfileRestServlet(RestServlet):
     PATTERNS = client_patterns("/profile/(?P<user_id>[^/]*)", v1=True)
 
-    def __init__(self, hs):
+    def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.hs = hs
         self.profile_handler = hs.get_profile_handler()
         self.auth = hs.get_auth()
 
-    async def on_GET(self, request, user_id):
+    async def on_GET(
+        self, request: SynapseRequest, user_id: str
+    ) -> Tuple[int, JsonDict]:
         requester_user = None
 
         if self.hs.config.require_auth_for_profile_requests:
@@ -149,7 +166,7 @@ class ProfileRestServlet(RestServlet):
         return 200, ret
 
 
-def register_servlets(hs, http_server):
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     ProfileDisplaynameRestServlet(hs).register(http_server)
     ProfileAvatarURLRestServlet(hs).register(http_server)
     ProfileRestServlet(hs).register(http_server)