Split `synapse.federation.transport.server` into multiple files. (#10590)

7 files changed, 2219 insertions, 2158 deletions

diff --git a/changelog.d/10590.misc b/changelog.d/10590.misc
new file mode 100644
index 0000000000..62fec717da
--- /dev/null
+++ b/changelog.d/10590.misc
@@ -0,0 +1 @@
+Re-organize the `synapse.federation.transport.server` module to create smaller files.
diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
deleted file mode 100644
index 79a2e1afa0..0000000000
--- a/synapse/federation/transport/server.py
+++ /dev/null
@@ -1,2158 +0,0 @@
-# Copyright 2014-2021 The Matrix.org Foundation C.I.C.
-# Copyright 2020 Sorunome
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-import functools
-import logging
-import re
-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
-from synapse.api.errors import Codes, FederationDeniedError, SynapseError
-from synapse.api.room_versions import RoomVersions
-from synapse.api.urls import (
-    FEDERATION_UNSTABLE_PREFIX,
-    FEDERATION_V1_PREFIX,
-    FEDERATION_V2_PREFIX,
-)
-from synapse.handlers.groups_local import GroupsLocalHandler
-from synapse.http.server import HttpServer, JsonResource
-from synapse.http.servlet import (
-    parse_boolean_from_args,
-    parse_integer_from_args,
-    parse_json_object_from_request,
-    parse_string_from_args,
-    parse_strings_from_args,
-)
-from synapse.logging import opentracing
-from synapse.logging.context import run_in_background
-from synapse.logging.opentracing import (
-    SynapseTags,
-    start_active_span,
-    start_active_span_from_request,
-    tags,
-    whitelisted_homeserver,
-)
-from synapse.server import HomeServer
-from synapse.types import JsonDict, ThirdPartyInstanceID, get_domain_from_id
-from synapse.util.ratelimitutils import FederationRateLimiter
-from synapse.util.stringutils import parse_and_validate_server_name
-from synapse.util.versionstring import get_version_string
-
-logger = logging.getLogger(__name__)
-
-
-class TransportLayerServer(JsonResource):
-    """Handles incoming federation HTTP requests"""
-
-    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: homeserver
-            servlet_groups: List of servlet groups to register.
-                Defaults to ``DEFAULT_SERVLET_GROUPS``.
-        """
-        self.hs = hs
-        self.clock = hs.get_clock()
-        self.servlet_groups = servlet_groups
-
-        super().__init__(hs, canonical_json=False)
-
-        self.authenticator = Authenticator(hs)
-        self.ratelimiter = hs.get_federation_ratelimiter()
-
-        self.register_servlets()
-
-    def register_servlets(self) -> None:
-        register_servlets(
-            self.hs,
-            resource=self,
-            ratelimiter=self.ratelimiter,
-            authenticator=self.authenticator,
-            servlet_groups=self.servlet_groups,
-        )
-
-
-class AuthenticationError(SynapseError):
-    """There was a problem authenticating the request"""
-
-
-class NoAuthenticationError(AuthenticationError):
-    """The request had no authentication information"""
-
-
-class Authenticator:
-    def __init__(self, hs: HomeServer):
-        self._clock = hs.get_clock()
-        self.keyring = hs.get_keyring()
-        self.server_name = hs.hostname
-        self.store = hs.get_datastore()
-        self.federation_domain_whitelist = hs.config.federation_domain_whitelist
-        self.notifier = hs.get_notifier()
-
-        self.replication_client = None
-        if hs.config.worker.worker_app:
-            self.replication_client = hs.get_tcp_replication()
-
-    # A method just so we can pass 'self' as the authenticator to the Servlets
-    async def authenticate_request(self, request, content):
-        now = self._clock.time_msec()
-        json_request = {
-            "method": request.method.decode("ascii"),
-            "uri": request.uri.decode("ascii"),
-            "destination": self.server_name,
-            "signatures": {},
-        }
-
-        if content is not None:
-            json_request["content"] = content
-
-        origin = None
-
-        auth_headers = request.requestHeaders.getRawHeaders(b"Authorization")
-
-        if not auth_headers:
-            raise NoAuthenticationError(
-                401, "Missing Authorization headers", Codes.UNAUTHORIZED
-            )
-
-        for auth in auth_headers:
-            if auth.startswith(b"X-Matrix"):
-                (origin, key, sig) = _parse_auth_header(auth)
-                json_request["origin"] = origin
-                json_request["signatures"].setdefault(origin, {})[key] = sig
-
-        if (
-            self.federation_domain_whitelist is not None
-            and origin not in self.federation_domain_whitelist
-        ):
-            raise FederationDeniedError(origin)
-
-        if origin is None or not json_request["signatures"]:
-            raise NoAuthenticationError(
-                401, "Missing Authorization headers", Codes.UNAUTHORIZED
-            )
-
-        await self.keyring.verify_json_for_server(
-            origin,
-            json_request,
-            now,
-        )
-
-        logger.debug("Request from %s", origin)
-        request.requester = origin
-
-        # If we get a valid signed request from the other side, its probably
-        # alive
-        retry_timings = await self.store.get_destination_retry_timings(origin)
-        if retry_timings and retry_timings.retry_last_ts:
-            run_in_background(self._reset_retry_timings, origin)
-
-        return origin
-
-    async def _reset_retry_timings(self, origin):
-        try:
-            logger.info("Marking origin %r as up", origin)
-            await self.store.set_destination_retry_timings(origin, None, 0, 0)
-
-            # Inform the relevant places that the remote server is back up.
-            self.notifier.notify_remote_server_up(origin)
-            if self.replication_client:
-                # If we're on a worker we try and inform master about this. The
-                # replication client doesn't hook into the notifier to avoid
-                # infinite loops where we send a `REMOTE_SERVER_UP` command to
-                # master, which then echoes it back to us which in turn pokes
-                # the notifier.
-                self.replication_client.send_remote_server_up(origin)
-
-        except Exception:
-            logger.exception("Error resetting retry timings on %s", origin)
-
-
-def _parse_auth_header(header_bytes):
-    """Parse an X-Matrix auth header
-
-    Args:
-        header_bytes (bytes): header value
-
-    Returns:
-        Tuple[str, str, str]: origin, key id, signature.
-
-    Raises:
-        AuthenticationError if the header could not be parsed
-    """
-    try:
-        header_str = header_bytes.decode("utf-8")
-        params = header_str.split(" ")[1].split(",")
-        param_dict = dict(kv.split("=") for kv in params)
-
-        def strip_quotes(value):
-            if value.startswith('"'):
-                return value[1:-1]
-            else:
-                return value
-
-        origin = strip_quotes(param_dict["origin"])
-
-        # ensure that the origin is a valid server name
-        parse_and_validate_server_name(origin)
-
-        key = strip_quotes(param_dict["key"])
-        sig = strip_quotes(param_dict["sig"])
-        return origin, key, sig
-    except Exception as e:
-        logger.warning(
-            "Error parsing auth header '%s': %s",
-            header_bytes.decode("ascii", "replace"),
-            e,
-        )
-        raise AuthenticationError(
-            400, "Malformed Authorization header", Codes.UNAUTHORIZED
-        )
-
-
-class BaseFederationServlet:
-    """Abstract base class for federation servlet classes.
-
-    The servlet object should have a PATH attribute which takes the form of a regexp to
-    match against the request path (excluding the /federation/v1 prefix).
-
-    The servlet should also implement one or more of on_GET, on_POST, on_PUT, to match
-    the appropriate HTTP method. These methods must be *asynchronous* and have the
-    signature:
-
-        on_<METHOD>(self, origin, content, query, **kwargs)
-
-        With arguments:
-
-            origin (unicode|None): The authenticated server_name of the calling server,
-                unless REQUIRE_AUTH is set to False and authentication failed.
-
-            content (unicode|None): decoded json body of the request. None if the
-                request was a GET.
-
-            query (dict[bytes, list[bytes]]): Query params from the request. url-decoded
-                (ie, '+' and '%xx' are decoded) but note that it is *not* utf8-decoded
-                yet.
-
-            **kwargs (dict[unicode, unicode]): the dict mapping keys to path
-                components as specified in the path match regexp.
-
-        Returns:
-            Optional[Tuple[int, object]]: either (response code, response object) to
-                 return a JSON response, or None if the request has already been handled.
-
-        Raises:
-            SynapseError: to return an error code
-
-            Exception: other exceptions will be caught, logged, and a 500 will be
-                returned.
-    """
-
-    PATH = ""  # Overridden in subclasses, the regex to match against the path.
-
-    REQUIRE_AUTH = True
-
-    PREFIX = FEDERATION_V1_PREFIX  # Allows specifying the API version
-
-    RATELIMIT = True  # Whether to rate limit requests or not
-
-    def __init__(
-        self,
-        hs: HomeServer,
-        authenticator: Authenticator,
-        ratelimiter: FederationRateLimiter,
-        server_name: str,
-    ):
-        self.hs = hs
-        self.authenticator = authenticator
-        self.ratelimiter = ratelimiter
-        self.server_name = server_name
-
-    def _wrap(self, func):
-        authenticator = self.authenticator
-        ratelimiter = self.ratelimiter
-
-        @functools.wraps(func)
-        async def new_func(request, *args, **kwargs):
-            """A callback which can be passed to HttpServer.RegisterPaths
-
-            Args:
-                request (twisted.web.http.Request):
-                *args: unused?
-                **kwargs (dict[unicode, unicode]): the dict mapping keys to path
-                    components as specified in the path match regexp.
-
-            Returns:
-                Tuple[int, object]|None: (response code, response object) as returned by
-                    the callback method. None if the request has already been handled.
-            """
-            content = None
-            if request.method in [b"PUT", b"POST"]:
-                # TODO: Handle other method types? other content types?
-                content = parse_json_object_from_request(request)
-
-            try:
-                origin = await authenticator.authenticate_request(request, content)
-            except NoAuthenticationError:
-                origin = None
-                if self.REQUIRE_AUTH:
-                    logger.warning(
-                        "authenticate_request failed: missing authentication"
-                    )
-                    raise
-            except Exception as e:
-                logger.warning("authenticate_request failed: %s", e)
-                raise
-
-            request_tags = {
-                SynapseTags.REQUEST_ID: request.get_request_id(),
-                tags.SPAN_KIND: tags.SPAN_KIND_RPC_SERVER,
-                tags.HTTP_METHOD: request.get_method(),
-                tags.HTTP_URL: request.get_redacted_uri(),
-                tags.PEER_HOST_IPV6: request.getClientIP(),
-                "authenticated_entity": origin,
-                "servlet_name": request.request_metrics.name,
-            }
-
-            # Only accept the span context if the origin is authenticated
-            # and whitelisted
-            if origin and whitelisted_homeserver(origin):
-                scope = start_active_span_from_request(
-                    request, "incoming-federation-request", tags=request_tags
-                )
-            else:
-                scope = start_active_span(
-                    "incoming-federation-request", tags=request_tags
-                )
-
-            with scope:
-                opentracing.inject_response_headers(request.responseHeaders)
-
-                if origin and self.RATELIMIT:
-                    with ratelimiter.ratelimit(origin) as d:
-                        await d
-                        if request._disconnected:
-                            logger.warning(
-                                "client disconnected before we started processing "
-                                "request"
-                            )
-                            return -1, None
-                        response = await func(
-                            origin, content, request.args, *args, **kwargs
-                        )
-                else:
-                    response = await func(
-                        origin, content, request.args, *args, **kwargs
-                    )
-
-            return response
-
-        return new_func
-
-    def register(self, server):
-        pattern = re.compile("^" + self.PREFIX + self.PATH + "$")
-
-        for method in ("GET", "PUT", "POST"):
-            code = getattr(self, "on_%s" % (method), None)
-            if code is None:
-                continue
-
-            server.register_paths(
-                method,
-                (pattern,),
-                self._wrap(code),
-                self.__class__.__name__,
-            )
-
-
-class BaseFederationServerServlet(BaseFederationServlet):
-    """Abstract base class for federation servlet classes which provides a federation server handler.
-
-    See BaseFederationServlet for more information.
-    """
-
-    def __init__(
-        self,
-        hs: HomeServer,
-        authenticator: Authenticator,
-        ratelimiter: FederationRateLimiter,
-        server_name: str,
-    ):
-        super().__init__(hs, authenticator, ratelimiter, server_name)
-        self.handler = hs.get_federation_server()
-
-
-class FederationSendServlet(BaseFederationServerServlet):
-    PATH = "/send/(?P<transaction_id>[^/]*)/?"
-
-    # We ratelimit manually in the handler as we queue up the requests and we
-    # don't want to fill up the ratelimiter with blocked requests.
-    RATELIMIT = False
-
-    # This is when someone is trying to send us a bunch of data.
-    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:
-            transaction_id: The transaction_id associated with this request. This
-                is *not* None.
-
-        Returns:
-            Tuple of `(code, response)`, where
-            `response` is a python dict to be converted into JSON that is
-            used as the response body.
-        """
-        # Parse the request
-        try:
-            transaction_data = content
-
-            logger.debug("Decoded %s: %s", transaction_id, str(transaction_data))
-
-            logger.info(
-                "Received txn %s from %s. (PDUs: %d, EDUs: %d)",
-                transaction_id,
-                origin,
-                len(transaction_data.get("pdus", [])),
-                len(transaction_data.get("edus", [])),
-            )
-
-        except Exception as e:
-            logger.exception(e)
-            return 400, {"error": "Invalid transaction"}
-
-        code, response = await self.handler.on_incoming_transaction(
-            origin, transaction_id, self.server_name, transaction_data
-        )
-
-        return code, response
-
-
-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: 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)
-
-
-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: 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,
-            parse_string_from_args(query, "event_id", None, required=False),
-        )
-
-
-class FederationStateIdsServlet(BaseFederationServerServlet):
-    PATH = "/state_ids/(?P<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,
-            parse_string_from_args(query, "event_id", None, required=True),
-        )
-
-
-class FederationBackfillServlet(BaseFederationServerServlet):
-    PATH = "/backfill/(?P<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)
-
-        if not limit:
-            return 400, {"error": "Did not include limit param"}
-
-        return await self.handler.on_backfill_request(origin, room_id, versions, limit)
-
-
-class FederationQueryServlet(BaseFederationServerServlet):
-    PATH = "/query/(?P<query_type>[^/]*)"
-
-    # This is when we receive a server-server Query
-    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)
-
-
-class FederationMakeJoinServlet(BaseFederationServerServlet):
-    PATH = "/make_join/(?P<room_id>[^/]*)/(?P<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: The authenticated server_name of the calling server
-
-            content: (GETs don't have bodies)
-
-            query: Query params from the request.
-
-            **kwargs: the dict mapping keys to path components as specified in
-                the path match regexp.
-
-        Returns:
-            Tuple of (response code, response object)
-        """
-        supported_versions = parse_strings_from_args(query, "ver", encoding="utf-8")
-        if supported_versions is None:
-            supported_versions = ["1"]
-
-        result = await self.handler.on_make_join_request(
-            origin, room_id, user_id, supported_versions=supported_versions
-        )
-        return 200, result
-
-
-class FederationMakeLeaveServlet(BaseFederationServerServlet):
-    PATH = "/make_leave/(?P<room_id>[^/]*)/(?P<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]:
-        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: 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):
-    PATH = "/send_leave/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
-
-    PREFIX = FEDERATION_V2_PREFIX
-
-    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: 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"
-        )
-
-        result = await self.handler.on_make_knock_request(
-            origin, room_id, user_id, supported_versions=supported_versions
-        )
-        return 200, result
-
-
-class FederationV1SendKnockServlet(BaseFederationServerServlet):
-    PATH = "/send_knock/(?P<room_id>[^/]*)/(?P<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]:
-        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: 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: 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
-        result = await self.handler.on_send_join_request(origin, content, room_id)
-        return 200, (200, result)
-
-
-class FederationV2SendJoinServlet(BaseFederationServerServlet):
-    PATH = "/send_join/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
-
-    PREFIX = FEDERATION_V2_PREFIX
-
-    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
-        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: 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
-        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, result)
-
-
-class FederationV2InviteServlet(BaseFederationServerServlet):
-    PATH = "/invite/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
-
-    PREFIX = FEDERATION_V2_PREFIX
-
-    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
-
-        room_version = content["room_version"]
-        event = content["event"]
-        invite_room_state = content["invite_room_state"]
-
-        # Synapse expects invite_room_state to be in unsigned, as it is in v1
-        # API
-
-        event.setdefault("unsigned", {})["invite_room_state"] = invite_room_state
-
-        result = await self.handler.on_invite_request(
-            origin, event, room_version_id=room_version
-        )
-        return 200, result
-
-
-class FederationThirdPartyInviteExchangeServlet(BaseFederationServerServlet):
-    PATH = "/exchange_third_party_invite/(?P<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, {}
-
-
-class FederationClientKeysQueryServlet(BaseFederationServerServlet):
-    PATH = "/user/keys/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: 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: str, content: JsonDict, query: Dict[bytes, List[bytes]]
-    ) -> Tuple[int, JsonDict]:
-        response = await self.handler.on_claim_client_keys(origin, content)
-        return 200, response
-
-
-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: 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", [])
-
-        result = await self.handler.on_get_missing_events(
-            origin,
-            room_id=room_id,
-            earliest_events=earliest_events,
-            latest_events=latest_events,
-            limit=limit,
-        )
-
-        return 200, result
-
-
-class On3pidBindServlet(BaseFederationServerServlet):
-    PATH = "/3pid/onbind"
-
-    REQUIRE_AUTH = False
-
-    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"]:
-                try:
-                    if "signed" not in invite or "token" not in invite["signed"]:
-                        message = (
-                            "Rejecting received notification of third-"
-                            "party invite without signed: %s" % (invite,)
-                        )
-                        logger.info(message)
-                        raise SynapseError(400, message)
-                    await self.handler.exchange_third_party_invite(
-                        invite["sender"],
-                        invite["mxid"],
-                        invite["room_id"],
-                        invite["signed"],
-                    )
-                except Exception as e:
-                    last_exception = e
-            if last_exception:
-                raise last_exception
-        return 200, {}
-
-
-class OpenIdUserInfo(BaseFederationServerServlet):
-    """
-    Exchange a bearer token for information about a user.
-
-    The response format should be compatible with:
-        http://openid.net/specs/openid-connect-core-1_0.html#UserInfoResponse
-
-    GET /openid/userinfo?access_token=ABDEFGH HTTP/1.1
-
-    HTTP/1.1 200 OK
-    Content-Type: application/json
-
-    {
-        "sub": "@userpart:example.org",
-    }
-    """
-
-    PATH = "/openid/userinfo"
-
-    REQUIRE_AUTH = False
-
-    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)
-
-        if user_id is None:
-            return (
-                401,
-                {
-                    "errcode": "M_UNKNOWN_TOKEN",
-                    "error": "Access Token unknown or expired",
-                },
-            )
-
-        return 200, {"sub": user_id}
-
-
-class PublicRoomList(BaseFederationServlet):
-    """
-    Fetch the public room list for this server.
-
-    This API returns information in the same format as /publicRooms on the
-    client API, but will only ever include local public rooms and hence is
-    intended for consumption by other homeservers.
-
-    GET /publicRooms HTTP/1.1
-
-    HTTP/1.1 200 OK
-    Content-Type: application/json
-
-    {
-        "chunk": [
-            {
-                "aliases": [
-                    "#test:localhost"
-                ],
-                "guest_can_join": false,
-                "name": "test room",
-                "num_joined_members": 3,
-                "room_id": "!whkydVegtvatLfXmPN:localhost",
-                "world_readable": false
-            }
-        ],
-        "end": "END",
-        "start": "START"
-    }
-    """
-
-    PATH = "/publicRooms"
-
-    def __init__(
-        self,
-        hs: HomeServer,
-        authenticator: Authenticator,
-        ratelimiter: FederationRateLimiter,
-        server_name: str,
-        allow_access: bool,
-    ):
-        super().__init__(hs, authenticator, ratelimiter, server_name)
-        self.handler = hs.get_room_list_handler()
-        self.allow_access = allow_access
-
-    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)
-
-        limit = parse_integer_from_args(query, "limit", 0)
-        since_token = parse_string_from_args(query, "since", None)
-        include_all_networks = parse_boolean_from_args(
-            query, "include_all_networks", default=False
-        )
-        third_party_instance_id = parse_string_from_args(
-            query, "third_party_instance_id", None
-        )
-
-        if include_all_networks:
-            network_tuple = None
-        elif third_party_instance_id:
-            network_tuple = ThirdPartyInstanceID.from_string(third_party_instance_id)
-        else:
-            network_tuple = ThirdPartyInstanceID(None, None)
-
-        if limit == 0:
-            # zero is a special value which corresponds to no limit.
-            limit = None
-
-        data = await self.handler.get_local_public_room_list(
-            limit, since_token, network_tuple=network_tuple, from_federation=True
-        )
-        return 200, data
-
-    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)
-
-        limit: Optional[int] = int(content.get("limit", 100))
-        since_token = content.get("since", None)
-        search_filter = content.get("filter", None)
-
-        include_all_networks = content.get("include_all_networks", False)
-        third_party_instance_id = content.get("third_party_instance_id", None)
-
-        if include_all_networks:
-            network_tuple = None
-            if third_party_instance_id is not None:
-                raise SynapseError(
-                    400, "Can't use include_all_networks with an explicit network"
-                )
-        elif third_party_instance_id is None:
-            network_tuple = ThirdPartyInstanceID(None, None)
-        else:
-            network_tuple = ThirdPartyInstanceID.from_string(third_party_instance_id)
-
-        if search_filter is None:
-            logger.warning("Nonefilter")
-
-        if limit == 0:
-            # zero is a special value which corresponds to no limit.
-            limit = None
-
-        data = await self.handler.get_local_public_room_list(
-            limit=limit,
-            since_token=since_token,
-            search_filter=search_filter,
-            network_tuple=network_tuple,
-            from_federation=True,
-        )
-
-        return 200, data
-
-
-class FederationVersionServlet(BaseFederationServlet):
-    PATH = "/version"
-
-    REQUIRE_AUTH = False
-
-    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)}},
-        )
-
-
-class BaseGroupsServerServlet(BaseFederationServlet):
-    """Abstract base class for federation servlet classes which provides a groups server handler.
-
-    See BaseFederationServlet for more information.
-    """
-
-    def __init__(
-        self,
-        hs: HomeServer,
-        authenticator: Authenticator,
-        ratelimiter: FederationRateLimiter,
-        server_name: str,
-    ):
-        super().__init__(hs, authenticator, ratelimiter, server_name)
-        self.handler = hs.get_groups_server_handler()
-
-
-class FederationGroupsProfileServlet(BaseGroupsServerServlet):
-    """Get/set the basic profile of a group on behalf of a user"""
-
-    PATH = "/groups/(?P<group_id>[^/]*)/profile"
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        new_content = await self.handler.get_group_profile(group_id, requester_user_id)
-
-        return 200, new_content
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        new_content = await self.handler.update_group_profile(
-            group_id, requester_user_id, content
-        )
-
-        return 200, new_content
-
-
-class FederationGroupsSummaryServlet(BaseGroupsServerServlet):
-    PATH = "/groups/(?P<group_id>[^/]*)/summary"
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        new_content = await self.handler.get_group_summary(group_id, requester_user_id)
-
-        return 200, new_content
-
-
-class FederationGroupsRoomsServlet(BaseGroupsServerServlet):
-    """Get the rooms in a group on behalf of a user"""
-
-    PATH = "/groups/(?P<group_id>[^/]*)/rooms"
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        new_content = await self.handler.get_rooms_in_group(group_id, requester_user_id)
-
-        return 200, new_content
-
-
-class FederationGroupsAddRoomsServlet(BaseGroupsServerServlet):
-    """Add/remove room from group"""
-
-    PATH = "/groups/(?P<group_id>[^/]*)/room/(?P<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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        new_content = await self.handler.add_room_to_group(
-            group_id, requester_user_id, room_id, content
-        )
-
-        return 200, new_content
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        new_content = await self.handler.remove_room_from_group(
-            group_id, requester_user_id, room_id
-        )
-
-        return 200, new_content
-
-
-class FederationGroupsAddRoomsConfigServlet(BaseGroupsServerServlet):
-    """Update room config in group"""
-
-    PATH = (
-        "/groups/(?P<group_id>[^/]*)/room/(?P<room_id>[^/]*)"
-        "/config/(?P<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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        result = await self.handler.update_room_in_group(
-            group_id, requester_user_id, room_id, config_key, content
-        )
-
-        return 200, result
-
-
-class FederationGroupsUsersServlet(BaseGroupsServerServlet):
-    """Get the users in a group on behalf of a user"""
-
-    PATH = "/groups/(?P<group_id>[^/]*)/users"
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        new_content = await self.handler.get_users_in_group(group_id, requester_user_id)
-
-        return 200, new_content
-
-
-class FederationGroupsInvitedUsersServlet(BaseGroupsServerServlet):
-    """Get the users that have been invited to a group"""
-
-    PATH = "/groups/(?P<group_id>[^/]*)/invited_users"
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        new_content = await self.handler.get_invited_users_in_group(
-            group_id, requester_user_id
-        )
-
-        return 200, new_content
-
-
-class FederationGroupsInviteServlet(BaseGroupsServerServlet):
-    """Ask a group server to invite someone to the group"""
-
-    PATH = "/groups/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/invite"
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        new_content = await self.handler.invite_to_group(
-            group_id, user_id, requester_user_id, content
-        )
-
-        return 200, new_content
-
-
-class FederationGroupsAcceptInviteServlet(BaseGroupsServerServlet):
-    """Accept an invitation from the group server"""
-
-    PATH = "/groups/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/accept_invite"
-
-    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")
-
-        new_content = await self.handler.accept_invite(group_id, user_id, content)
-
-        return 200, new_content
-
-
-class FederationGroupsJoinServlet(BaseGroupsServerServlet):
-    """Attempt to join a group"""
-
-    PATH = "/groups/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/join"
-
-    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")
-
-        new_content = await self.handler.join_group(group_id, user_id, content)
-
-        return 200, new_content
-
-
-class FederationGroupsRemoveUserServlet(BaseGroupsServerServlet):
-    """Leave or kick a user from the group"""
-
-    PATH = "/groups/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/remove"
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        new_content = await self.handler.remove_user_from_group(
-            group_id, user_id, requester_user_id, content
-        )
-
-        return 200, new_content
-
-
-class BaseGroupsLocalServlet(BaseFederationServlet):
-    """Abstract base class for federation servlet classes which provides a groups local handler.
-
-    See BaseFederationServlet for more information.
-    """
-
-    def __init__(
-        self,
-        hs: HomeServer,
-        authenticator: Authenticator,
-        ratelimiter: FederationRateLimiter,
-        server_name: str,
-    ):
-        super().__init__(hs, authenticator, ratelimiter, server_name)
-        self.handler = hs.get_groups_local_handler()
-
-
-class FederationGroupsLocalInviteServlet(BaseGroupsLocalServlet):
-    """A group server has invited a local user"""
-
-    PATH = "/groups/local/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/invite"
-
-    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")
-
-        assert isinstance(
-            self.handler, GroupsLocalHandler
-        ), "Workers cannot handle group invites."
-
-        new_content = await self.handler.on_invite(group_id, user_id, content)
-
-        return 200, new_content
-
-
-class FederationGroupsRemoveLocalUserServlet(BaseGroupsLocalServlet):
-    """A group server has removed a local user"""
-
-    PATH = "/groups/local/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/remove"
-
-    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")
-
-        assert isinstance(
-            self.handler, GroupsLocalHandler
-        ), "Workers cannot handle group removals."
-
-        await self.handler.user_removed_from_group(group_id, user_id, content)
-
-        return 200, None
-
-
-class FederationGroupsRenewAttestaionServlet(BaseFederationServlet):
-    """A group or user's server renews their attestation"""
-
-    PATH = "/groups/(?P<group_id>[^/]*)/renew_attestation/(?P<user_id>[^/]*)"
-
-    def __init__(
-        self,
-        hs: HomeServer,
-        authenticator: Authenticator,
-        ratelimiter: FederationRateLimiter,
-        server_name: str,
-    ):
-        super().__init__(hs, authenticator, ratelimiter, server_name)
-        self.handler = hs.get_groups_attestation_renewer()
-
-    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(
-            group_id, user_id, content
-        )
-
-        return 200, new_content
-
-
-class FederationGroupsSummaryRoomsServlet(BaseGroupsServerServlet):
-    """Add/remove a room from the group summary, with optional category.
-
-    Matches both:
-        - /groups/:group/summary/rooms/:room_id
-        - /groups/:group/summary/categories/:category/rooms/:room_id
-    """
-
-    PATH = (
-        "/groups/(?P<group_id>[^/]*)/summary"
-        "(/categories/(?P<category_id>[^/]+))?"
-        "/rooms/(?P<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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        if category_id == "":
-            raise SynapseError(
-                400, "category_id cannot be empty string", Codes.INVALID_PARAM
-            )
-
-        if len(category_id) > MAX_GROUP_CATEGORYID_LENGTH:
-            raise SynapseError(
-                400,
-                "category_id may not be longer than %s characters"
-                % (MAX_GROUP_CATEGORYID_LENGTH,),
-                Codes.INVALID_PARAM,
-            )
-
-        resp = await self.handler.update_group_summary_room(
-            group_id,
-            requester_user_id,
-            room_id=room_id,
-            category_id=category_id,
-            content=content,
-        )
-
-        return 200, resp
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        if category_id == "":
-            raise SynapseError(400, "category_id cannot be empty string")
-
-        resp = await self.handler.delete_group_summary_room(
-            group_id, requester_user_id, room_id=room_id, category_id=category_id
-        )
-
-        return 200, resp
-
-
-class FederationGroupsCategoriesServlet(BaseGroupsServerServlet):
-    """Get all categories for a group"""
-
-    PATH = "/groups/(?P<group_id>[^/]*)/categories/?"
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        resp = await self.handler.get_group_categories(group_id, requester_user_id)
-
-        return 200, resp
-
-
-class FederationGroupsCategoryServlet(BaseGroupsServerServlet):
-    """Add/remove/get a category in a group"""
-
-    PATH = "/groups/(?P<group_id>[^/]*)/categories/(?P<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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        resp = await self.handler.get_group_category(
-            group_id, requester_user_id, category_id
-        )
-
-        return 200, resp
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        if category_id == "":
-            raise SynapseError(400, "category_id cannot be empty string")
-
-        if len(category_id) > MAX_GROUP_CATEGORYID_LENGTH:
-            raise SynapseError(
-                400,
-                "category_id may not be longer than %s characters"
-                % (MAX_GROUP_CATEGORYID_LENGTH,),
-                Codes.INVALID_PARAM,
-            )
-
-        resp = await self.handler.upsert_group_category(
-            group_id, requester_user_id, category_id, content
-        )
-
-        return 200, resp
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        if category_id == "":
-            raise SynapseError(400, "category_id cannot be empty string")
-
-        resp = await self.handler.delete_group_category(
-            group_id, requester_user_id, category_id
-        )
-
-        return 200, resp
-
-
-class FederationGroupsRolesServlet(BaseGroupsServerServlet):
-    """Get roles in a group"""
-
-    PATH = "/groups/(?P<group_id>[^/]*)/roles/?"
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        resp = await self.handler.get_group_roles(group_id, requester_user_id)
-
-        return 200, resp
-
-
-class FederationGroupsRoleServlet(BaseGroupsServerServlet):
-    """Add/remove/get a role in a group"""
-
-    PATH = "/groups/(?P<group_id>[^/]*)/roles/(?P<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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        resp = await self.handler.get_group_role(group_id, requester_user_id, role_id)
-
-        return 200, resp
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        if role_id == "":
-            raise SynapseError(
-                400, "role_id cannot be empty string", Codes.INVALID_PARAM
-            )
-
-        if len(role_id) > MAX_GROUP_ROLEID_LENGTH:
-            raise SynapseError(
-                400,
-                "role_id may not be longer than %s characters"
-                % (MAX_GROUP_ROLEID_LENGTH,),
-                Codes.INVALID_PARAM,
-            )
-
-        resp = await self.handler.update_group_role(
-            group_id, requester_user_id, role_id, content
-        )
-
-        return 200, resp
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        if role_id == "":
-            raise SynapseError(400, "role_id cannot be empty string")
-
-        resp = await self.handler.delete_group_role(
-            group_id, requester_user_id, role_id
-        )
-
-        return 200, resp
-
-
-class FederationGroupsSummaryUsersServlet(BaseGroupsServerServlet):
-    """Add/remove a user from the group summary, with optional role.
-
-    Matches both:
-        - /groups/:group/summary/users/:user_id
-        - /groups/:group/summary/roles/:role/users/:user_id
-    """
-
-    PATH = (
-        "/groups/(?P<group_id>[^/]*)/summary"
-        "(/roles/(?P<role_id>[^/]+))?"
-        "/users/(?P<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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        if role_id == "":
-            raise SynapseError(400, "role_id cannot be empty string")
-
-        if len(role_id) > MAX_GROUP_ROLEID_LENGTH:
-            raise SynapseError(
-                400,
-                "role_id may not be longer than %s characters"
-                % (MAX_GROUP_ROLEID_LENGTH,),
-                Codes.INVALID_PARAM,
-            )
-
-        resp = await self.handler.update_group_summary_user(
-            group_id,
-            requester_user_id,
-            user_id=user_id,
-            role_id=role_id,
-            content=content,
-        )
-
-        return 200, resp
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        if role_id == "":
-            raise SynapseError(400, "role_id cannot be empty string")
-
-        resp = await self.handler.delete_group_summary_user(
-            group_id, requester_user_id, user_id=user_id, role_id=role_id
-        )
-
-        return 200, resp
-
-
-class FederationGroupsBulkPublicisedServlet(BaseGroupsLocalServlet):
-    """Get roles in a group"""
-
-    PATH = "/get_groups_publicised"
-
-    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
-        )
-
-        return 200, resp
-
-
-class FederationGroupsSettingJoinPolicyServlet(BaseGroupsServerServlet):
-    """Sets whether a group is joinable without an invite or knock"""
-
-    PATH = "/groups/(?P<group_id>[^/]*)/settings/m.join_policy"
-
-    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", required=True
-        )
-        if get_domain_from_id(requester_user_id) != origin:
-            raise SynapseError(403, "requester_user_id doesn't match origin")
-
-        new_content = await self.handler.set_group_join_policy(
-            group_id, requester_user_id, content
-        )
-
-        return 200, new_content
-
-
-class FederationSpaceSummaryServlet(BaseFederationServlet):
-    PREFIX = FEDERATION_UNSTABLE_PREFIX + "/org.matrix.msc2946"
-    PATH = "/spaces/(?P<room_id>[^/]*)"
-
-    def __init__(
-        self,
-        hs: HomeServer,
-        authenticator: Authenticator,
-        ratelimiter: FederationRateLimiter,
-        server_name: str,
-    ):
-        super().__init__(hs, authenticator, ratelimiter, server_name)
-        self.handler = hs.get_space_summary_handler()
-
-    async def on_GET(
-        self,
-        origin: str,
-        content: Literal[None],
-        query: Mapping[bytes, Sequence[bytes]],
-        room_id: str,
-    ) -> Tuple[int, JsonDict]:
-        suggested_only = parse_boolean_from_args(query, "suggested_only", default=False)
-        max_rooms_per_space = parse_integer_from_args(query, "max_rooms_per_space")
-
-        exclude_rooms = parse_strings_from_args(query, "exclude_rooms", default=[])
-
-        return 200, await self.handler.federation_space_summary(
-            origin, room_id, suggested_only, max_rooms_per_space, exclude_rooms
-        )
-
-    # TODO When switching to the stable endpoint, remove the POST handler.
-    async def on_POST(
-        self,
-        origin: str,
-        content: JsonDict,
-        query: Mapping[bytes, Sequence[bytes]],
-        room_id: str,
-    ) -> Tuple[int, JsonDict]:
-        suggested_only = content.get("suggested_only", False)
-        if not isinstance(suggested_only, bool):
-            raise SynapseError(
-                400, "'suggested_only' must be a boolean", Codes.BAD_JSON
-            )
-
-        exclude_rooms = content.get("exclude_rooms", [])
-        if not isinstance(exclude_rooms, list) or any(
-            not isinstance(x, str) for x in exclude_rooms
-        ):
-            raise SynapseError(400, "bad value for 'exclude_rooms'", Codes.BAD_JSON)
-
-        max_rooms_per_space = content.get("max_rooms_per_space")
-        if max_rooms_per_space is not None and not isinstance(max_rooms_per_space, int):
-            raise SynapseError(
-                400, "bad value for 'max_rooms_per_space'", Codes.BAD_JSON
-            )
-
-        return 200, await self.handler.federation_space_summary(
-            origin, room_id, suggested_only, max_rooms_per_space, exclude_rooms
-        )
-
-
-class FederationRoomHierarchyServlet(BaseFederationServlet):
-    PREFIX = FEDERATION_UNSTABLE_PREFIX + "/org.matrix.msc2946"
-    PATH = "/hierarchy/(?P<room_id>[^/]*)"
-
-    def __init__(
-        self,
-        hs: HomeServer,
-        authenticator: Authenticator,
-        ratelimiter: FederationRateLimiter,
-        server_name: str,
-    ):
-        super().__init__(hs, authenticator, ratelimiter, server_name)
-        self.handler = hs.get_space_summary_handler()
-
-    async def on_GET(
-        self,
-        origin: str,
-        content: Literal[None],
-        query: Mapping[bytes, Sequence[bytes]],
-        room_id: str,
-    ) -> Tuple[int, JsonDict]:
-        suggested_only = parse_boolean_from_args(query, "suggested_only", default=False)
-        return 200, await self.handler.get_federation_hierarchy(
-            origin, room_id, suggested_only
-        )
-
-
-class RoomComplexityServlet(BaseFederationServlet):
-    """
-    Indicates to other servers how complex (and therefore likely
-    resource-intensive) a public room this server knows about is.
-    """
-
-    PATH = "/rooms/(?P<room_id>[^/]*)/complexity"
-    PREFIX = FEDERATION_UNSTABLE_PREFIX
-
-    def __init__(
-        self,
-        hs: HomeServer,
-        authenticator: Authenticator,
-        ratelimiter: FederationRateLimiter,
-        server_name: str,
-    ):
-        super().__init__(hs, authenticator, ratelimiter, server_name)
-        self._store = self.hs.get_datastore()
-
-    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
-        )
-
-        if not is_public:
-            raise SynapseError(404, "Room not found", errcode=Codes.INVALID_PARAM)
-
-        complexity = await self._store.get_room_complexity(room_id)
-        return 200, complexity
-
-
-FEDERATION_SERVLET_CLASSES: Tuple[Type[BaseFederationServlet], ...] = (
-    FederationSendServlet,
-    FederationEventServlet,
-    FederationStateV1Servlet,
-    FederationStateIdsServlet,
-    FederationBackfillServlet,
-    FederationQueryServlet,
-    FederationMakeJoinServlet,
-    FederationMakeLeaveServlet,
-    FederationEventServlet,
-    FederationV1SendJoinServlet,
-    FederationV2SendJoinServlet,
-    FederationV1SendLeaveServlet,
-    FederationV2SendLeaveServlet,
-    FederationV1InviteServlet,
-    FederationV2InviteServlet,
-    FederationGetMissingEventsServlet,
-    FederationEventAuthServlet,
-    FederationClientKeysQueryServlet,
-    FederationUserDevicesQueryServlet,
-    FederationClientKeysClaimServlet,
-    FederationThirdPartyInviteExchangeServlet,
-    On3pidBindServlet,
-    FederationVersionServlet,
-    RoomComplexityServlet,
-    FederationSpaceSummaryServlet,
-    FederationRoomHierarchyServlet,
-    FederationV1SendKnockServlet,
-    FederationMakeKnockServlet,
-)
-
-OPENID_SERVLET_CLASSES: Tuple[Type[BaseFederationServlet], ...] = (OpenIdUserInfo,)
-
-ROOM_LIST_CLASSES: Tuple[Type[PublicRoomList], ...] = (PublicRoomList,)
-
-GROUP_SERVER_SERVLET_CLASSES: Tuple[Type[BaseFederationServlet], ...] = (
-    FederationGroupsProfileServlet,
-    FederationGroupsSummaryServlet,
-    FederationGroupsRoomsServlet,
-    FederationGroupsUsersServlet,
-    FederationGroupsInvitedUsersServlet,
-    FederationGroupsInviteServlet,
-    FederationGroupsAcceptInviteServlet,
-    FederationGroupsJoinServlet,
-    FederationGroupsRemoveUserServlet,
-    FederationGroupsSummaryRoomsServlet,
-    FederationGroupsCategoriesServlet,
-    FederationGroupsCategoryServlet,
-    FederationGroupsRolesServlet,
-    FederationGroupsRoleServlet,
-    FederationGroupsSummaryUsersServlet,
-    FederationGroupsAddRoomsServlet,
-    FederationGroupsAddRoomsConfigServlet,
-    FederationGroupsSettingJoinPolicyServlet,
-)
-
-
-GROUP_LOCAL_SERVLET_CLASSES: Tuple[Type[BaseFederationServlet], ...] = (
-    FederationGroupsLocalInviteServlet,
-    FederationGroupsRemoveLocalUserServlet,
-    FederationGroupsBulkPublicisedServlet,
-)
-
-
-GROUP_ATTESTATION_SERVLET_CLASSES: Tuple[Type[BaseFederationServlet], ...] = (
-    FederationGroupsRenewAttestaionServlet,
-)
-
-
-DEFAULT_SERVLET_GROUPS = (
-    "federation",
-    "room_list",
-    "group_server",
-    "group_local",
-    "group_attestation",
-    "openid",
-)
-
-
-def register_servlets(
-    hs: HomeServer,
-    resource: HttpServer,
-    authenticator: Authenticator,
-    ratelimiter: FederationRateLimiter,
-    servlet_groups: Optional[Container[str]] = None,
-):
-    """Initialize and register servlet classes.
-
-    Will by default register all servlets. For custom behaviour, pass in
-    a list of servlet_groups to register.
-
-    Args:
-        hs: homeserver
-        resource: resource class to register to
-        authenticator: authenticator to use
-        ratelimiter: ratelimiter to use
-        servlet_groups: List of servlet groups to register.
-            Defaults to ``DEFAULT_SERVLET_GROUPS``.
-    """
-    if not servlet_groups:
-        servlet_groups = DEFAULT_SERVLET_GROUPS
-
-    if "federation" in servlet_groups:
-        for servletclass in FEDERATION_SERVLET_CLASSES:
-            servletclass(
-                hs=hs,
-                authenticator=authenticator,
-                ratelimiter=ratelimiter,
-                server_name=hs.hostname,
-            ).register(resource)
-
-    if "openid" in servlet_groups:
-        for servletclass in OPENID_SERVLET_CLASSES:
-            servletclass(
-                hs=hs,
-                authenticator=authenticator,
-                ratelimiter=ratelimiter,
-                server_name=hs.hostname,
-            ).register(resource)
-
-    if "room_list" in servlet_groups:
-        for servletclass in ROOM_LIST_CLASSES:
-            servletclass(
-                hs=hs,
-                authenticator=authenticator,
-                ratelimiter=ratelimiter,
-                server_name=hs.hostname,
-                allow_access=hs.config.allow_public_rooms_over_federation,
-            ).register(resource)
-
-    if "group_server" in servlet_groups:
-        for servletclass in GROUP_SERVER_SERVLET_CLASSES:
-            servletclass(
-                hs=hs,
-                authenticator=authenticator,
-                ratelimiter=ratelimiter,
-                server_name=hs.hostname,
-            ).register(resource)
-
-    if "group_local" in servlet_groups:
-        for servletclass in GROUP_LOCAL_SERVLET_CLASSES:
-            servletclass(
-                hs=hs,
-                authenticator=authenticator,
-                ratelimiter=ratelimiter,
-                server_name=hs.hostname,
-            ).register(resource)
-
-    if "group_attestation" in servlet_groups:
-        for servletclass in GROUP_ATTESTATION_SERVLET_CLASSES:
-            servletclass(
-                hs=hs,
-                authenticator=authenticator,
-                ratelimiter=ratelimiter,
-                server_name=hs.hostname,
-            ).register(resource)
diff --git a/synapse/federation/transport/server/__init__.py b/synapse/federation/transport/server/__init__.py
new file mode 100644
index 0000000000..95176ba6f9
--- /dev/null
+++ b/synapse/federation/transport/server/__init__.py
@@ -0,0 +1,332 @@
+# Copyright 2014-2021 The Matrix.org Foundation C.I.C.
+# Copyright 2020 Sorunome
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import logging
+from typing import Dict, Iterable, List, Optional, Tuple, Type
+
+from typing_extensions import Literal
+
+from synapse.api.errors import FederationDeniedError, SynapseError
+from synapse.federation.transport.server._base import (
+    Authenticator,
+    BaseFederationServlet,
+)
+from synapse.federation.transport.server.federation import FEDERATION_SERVLET_CLASSES
+from synapse.federation.transport.server.groups_local import GROUP_LOCAL_SERVLET_CLASSES
+from synapse.federation.transport.server.groups_server import (
+    GROUP_SERVER_SERVLET_CLASSES,
+)
+from synapse.http.server import HttpServer, JsonResource
+from synapse.http.servlet import (
+    parse_boolean_from_args,
+    parse_integer_from_args,
+    parse_string_from_args,
+)
+from synapse.server import HomeServer
+from synapse.types import JsonDict, ThirdPartyInstanceID
+from synapse.util.ratelimitutils import FederationRateLimiter
+
+logger = logging.getLogger(__name__)
+
+
+class TransportLayerServer(JsonResource):
+    """Handles incoming federation HTTP requests"""
+
+    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: homeserver
+            servlet_groups: List of servlet groups to register.
+                Defaults to ``DEFAULT_SERVLET_GROUPS``.
+        """
+        self.hs = hs
+        self.clock = hs.get_clock()
+        self.servlet_groups = servlet_groups
+
+        super().__init__(hs, canonical_json=False)
+
+        self.authenticator = Authenticator(hs)
+        self.ratelimiter = hs.get_federation_ratelimiter()
+
+        self.register_servlets()
+
+    def register_servlets(self) -> None:
+        register_servlets(
+            self.hs,
+            resource=self,
+            ratelimiter=self.ratelimiter,
+            authenticator=self.authenticator,
+            servlet_groups=self.servlet_groups,
+        )
+
+
+class PublicRoomList(BaseFederationServlet):
+    """
+    Fetch the public room list for this server.
+
+    This API returns information in the same format as /publicRooms on the
+    client API, but will only ever include local public rooms and hence is
+    intended for consumption by other homeservers.
+
+    GET /publicRooms HTTP/1.1
+
+    HTTP/1.1 200 OK
+    Content-Type: application/json
+
+    {
+        "chunk": [
+            {
+                "aliases": [
+                    "#test:localhost"
+                ],
+                "guest_can_join": false,
+                "name": "test room",
+                "num_joined_members": 3,
+                "room_id": "!whkydVegtvatLfXmPN:localhost",
+                "world_readable": false
+            }
+        ],
+        "end": "END",
+        "start": "START"
+    }
+    """
+
+    PATH = "/publicRooms"
+
+    def __init__(
+        self,
+        hs: HomeServer,
+        authenticator: Authenticator,
+        ratelimiter: FederationRateLimiter,
+        server_name: str,
+    ):
+        super().__init__(hs, authenticator, ratelimiter, server_name)
+        self.handler = hs.get_room_list_handler()
+        self.allow_access = hs.config.allow_public_rooms_over_federation
+
+    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)
+
+        limit = parse_integer_from_args(query, "limit", 0)
+        since_token = parse_string_from_args(query, "since", None)
+        include_all_networks = parse_boolean_from_args(
+            query, "include_all_networks", default=False
+        )
+        third_party_instance_id = parse_string_from_args(
+            query, "third_party_instance_id", None
+        )
+
+        if include_all_networks:
+            network_tuple = None
+        elif third_party_instance_id:
+            network_tuple = ThirdPartyInstanceID.from_string(third_party_instance_id)
+        else:
+            network_tuple = ThirdPartyInstanceID(None, None)
+
+        if limit == 0:
+            # zero is a special value which corresponds to no limit.
+            limit = None
+
+        data = await self.handler.get_local_public_room_list(
+            limit, since_token, network_tuple=network_tuple, from_federation=True
+        )
+        return 200, data
+
+    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)
+
+        limit: Optional[int] = int(content.get("limit", 100))
+        since_token = content.get("since", None)
+        search_filter = content.get("filter", None)
+
+        include_all_networks = content.get("include_all_networks", False)
+        third_party_instance_id = content.get("third_party_instance_id", None)
+
+        if include_all_networks:
+            network_tuple = None
+            if third_party_instance_id is not None:
+                raise SynapseError(
+                    400, "Can't use include_all_networks with an explicit network"
+                )
+        elif third_party_instance_id is None:
+            network_tuple = ThirdPartyInstanceID(None, None)
+        else:
+            network_tuple = ThirdPartyInstanceID.from_string(third_party_instance_id)
+
+        if search_filter is None:
+            logger.warning("Nonefilter")
+
+        if limit == 0:
+            # zero is a special value which corresponds to no limit.
+            limit = None
+
+        data = await self.handler.get_local_public_room_list(
+            limit=limit,
+            since_token=since_token,
+            search_filter=search_filter,
+            network_tuple=network_tuple,
+            from_federation=True,
+        )
+
+        return 200, data
+
+
+class FederationGroupsRenewAttestaionServlet(BaseFederationServlet):
+    """A group or user's server renews their attestation"""
+
+    PATH = "/groups/(?P<group_id>[^/]*)/renew_attestation/(?P<user_id>[^/]*)"
+
+    def __init__(
+        self,
+        hs: HomeServer,
+        authenticator: Authenticator,
+        ratelimiter: FederationRateLimiter,
+        server_name: str,
+    ):
+        super().__init__(hs, authenticator, ratelimiter, server_name)
+        self.handler = hs.get_groups_attestation_renewer()
+
+    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(
+            group_id, user_id, content
+        )
+
+        return 200, new_content
+
+
+class OpenIdUserInfo(BaseFederationServlet):
+    """
+    Exchange a bearer token for information about a user.
+
+    The response format should be compatible with:
+        http://openid.net/specs/openid-connect-core-1_0.html#UserInfoResponse
+
+    GET /openid/userinfo?access_token=ABDEFGH HTTP/1.1
+
+    HTTP/1.1 200 OK
+    Content-Type: application/json
+
+    {
+        "sub": "@userpart:example.org",
+    }
+    """
+
+    PATH = "/openid/userinfo"
+
+    REQUIRE_AUTH = False
+
+    def __init__(
+        self,
+        hs: HomeServer,
+        authenticator: Authenticator,
+        ratelimiter: FederationRateLimiter,
+        server_name: str,
+    ):
+        super().__init__(hs, authenticator, ratelimiter, server_name)
+        self.handler = hs.get_federation_server()
+
+    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)
+
+        if user_id is None:
+            return (
+                401,
+                {
+                    "errcode": "M_UNKNOWN_TOKEN",
+                    "error": "Access Token unknown or expired",
+                },
+            )
+
+        return 200, {"sub": user_id}
+
+
+DEFAULT_SERVLET_GROUPS: Dict[str, Iterable[Type[BaseFederationServlet]]] = {
+    "federation": FEDERATION_SERVLET_CLASSES,
+    "room_list": (PublicRoomList,),
+    "group_server": GROUP_SERVER_SERVLET_CLASSES,
+    "group_local": GROUP_LOCAL_SERVLET_CLASSES,
+    "group_attestation": (FederationGroupsRenewAttestaionServlet,),
+    "openid": (OpenIdUserInfo,),
+}
+
+
+def register_servlets(
+    hs: HomeServer,
+    resource: HttpServer,
+    authenticator: Authenticator,
+    ratelimiter: FederationRateLimiter,
+    servlet_groups: Optional[Iterable[str]] = None,
+):
+    """Initialize and register servlet classes.
+
+    Will by default register all servlets. For custom behaviour, pass in
+    a list of servlet_groups to register.
+
+    Args:
+        hs: homeserver
+        resource: resource class to register to
+        authenticator: authenticator to use
+        ratelimiter: ratelimiter to use
+        servlet_groups: List of servlet groups to register.
+            Defaults to ``DEFAULT_SERVLET_GROUPS``.
+    """
+    if not servlet_groups:
+        servlet_groups = DEFAULT_SERVLET_GROUPS.keys()
+
+    for servlet_group in servlet_groups:
+        # Skip unknown servlet groups.
+        if servlet_group not in DEFAULT_SERVLET_GROUPS:
+            raise RuntimeError(
+                f"Attempting to register unknown federation servlet: '{servlet_group}'"
+            )
+
+        for servletclass in DEFAULT_SERVLET_GROUPS[servlet_group]:
+            servletclass(
+                hs=hs,
+                authenticator=authenticator,
+                ratelimiter=ratelimiter,
+                server_name=hs.hostname,
+            ).register(resource)
diff --git a/synapse/federation/transport/server/_base.py b/synapse/federation/transport/server/_base.py
new file mode 100644
index 0000000000..624c859f1e
--- /dev/null
+++ b/synapse/federation/transport/server/_base.py
@@ -0,0 +1,328 @@
+#  Copyright 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.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+import functools
+import logging
+import re
+
+from synapse.api.errors import Codes, FederationDeniedError, SynapseError
+from synapse.api.urls import FEDERATION_V1_PREFIX
+from synapse.http.servlet import parse_json_object_from_request
+from synapse.logging import opentracing
+from synapse.logging.context import run_in_background
+from synapse.logging.opentracing import (
+    SynapseTags,
+    start_active_span,
+    start_active_span_from_request,
+    tags,
+    whitelisted_homeserver,
+)
+from synapse.server import HomeServer
+from synapse.util.ratelimitutils import FederationRateLimiter
+from synapse.util.stringutils import parse_and_validate_server_name
+
+logger = logging.getLogger(__name__)
+
+
+class AuthenticationError(SynapseError):
+    """There was a problem authenticating the request"""
+
+
+class NoAuthenticationError(AuthenticationError):
+    """The request had no authentication information"""
+
+
+class Authenticator:
+    def __init__(self, hs: HomeServer):
+        self._clock = hs.get_clock()
+        self.keyring = hs.get_keyring()
+        self.server_name = hs.hostname
+        self.store = hs.get_datastore()
+        self.federation_domain_whitelist = hs.config.federation_domain_whitelist
+        self.notifier = hs.get_notifier()
+
+        self.replication_client = None
+        if hs.config.worker.worker_app:
+            self.replication_client = hs.get_tcp_replication()
+
+    # A method just so we can pass 'self' as the authenticator to the Servlets
+    async def authenticate_request(self, request, content):
+        now = self._clock.time_msec()
+        json_request = {
+            "method": request.method.decode("ascii"),
+            "uri": request.uri.decode("ascii"),
+            "destination": self.server_name,
+            "signatures": {},
+        }
+
+        if content is not None:
+            json_request["content"] = content
+
+        origin = None
+
+        auth_headers = request.requestHeaders.getRawHeaders(b"Authorization")
+
+        if not auth_headers:
+            raise NoAuthenticationError(
+                401, "Missing Authorization headers", Codes.UNAUTHORIZED
+            )
+
+        for auth in auth_headers:
+            if auth.startswith(b"X-Matrix"):
+                (origin, key, sig) = _parse_auth_header(auth)
+                json_request["origin"] = origin
+                json_request["signatures"].setdefault(origin, {})[key] = sig
+
+        if (
+            self.federation_domain_whitelist is not None
+            and origin not in self.federation_domain_whitelist
+        ):
+            raise FederationDeniedError(origin)
+
+        if origin is None or not json_request["signatures"]:
+            raise NoAuthenticationError(
+                401, "Missing Authorization headers", Codes.UNAUTHORIZED
+            )
+
+        await self.keyring.verify_json_for_server(
+            origin,
+            json_request,
+            now,
+        )
+
+        logger.debug("Request from %s", origin)
+        request.requester = origin
+
+        # If we get a valid signed request from the other side, its probably
+        # alive
+        retry_timings = await self.store.get_destination_retry_timings(origin)
+        if retry_timings and retry_timings.retry_last_ts:
+            run_in_background(self._reset_retry_timings, origin)
+
+        return origin
+
+    async def _reset_retry_timings(self, origin):
+        try:
+            logger.info("Marking origin %r as up", origin)
+            await self.store.set_destination_retry_timings(origin, None, 0, 0)
+
+            # Inform the relevant places that the remote server is back up.
+            self.notifier.notify_remote_server_up(origin)
+            if self.replication_client:
+                # If we're on a worker we try and inform master about this. The
+                # replication client doesn't hook into the notifier to avoid
+                # infinite loops where we send a `REMOTE_SERVER_UP` command to
+                # master, which then echoes it back to us which in turn pokes
+                # the notifier.
+                self.replication_client.send_remote_server_up(origin)
+
+        except Exception:
+            logger.exception("Error resetting retry timings on %s", origin)
+
+
+def _parse_auth_header(header_bytes):
+    """Parse an X-Matrix auth header
+
+    Args:
+        header_bytes (bytes): header value
+
+    Returns:
+        Tuple[str, str, str]: origin, key id, signature.
+
+    Raises:
+        AuthenticationError if the header could not be parsed
+    """
+    try:
+        header_str = header_bytes.decode("utf-8")
+        params = header_str.split(" ")[1].split(",")
+        param_dict = dict(kv.split("=") for kv in params)
+
+        def strip_quotes(value):
+            if value.startswith('"'):
+                return value[1:-1]
+            else:
+                return value
+
+        origin = strip_quotes(param_dict["origin"])
+
+        # ensure that the origin is a valid server name
+        parse_and_validate_server_name(origin)
+
+        key = strip_quotes(param_dict["key"])
+        sig = strip_quotes(param_dict["sig"])
+        return origin, key, sig
+    except Exception as e:
+        logger.warning(
+            "Error parsing auth header '%s': %s",
+            header_bytes.decode("ascii", "replace"),
+            e,
+        )
+        raise AuthenticationError(
+            400, "Malformed Authorization header", Codes.UNAUTHORIZED
+        )
+
+
+class BaseFederationServlet:
+    """Abstract base class for federation servlet classes.
+
+    The servlet object should have a PATH attribute which takes the form of a regexp to
+    match against the request path (excluding the /federation/v1 prefix).
+
+    The servlet should also implement one or more of on_GET, on_POST, on_PUT, to match
+    the appropriate HTTP method. These methods must be *asynchronous* and have the
+    signature:
+
+        on_<METHOD>(self, origin, content, query, **kwargs)
+
+        With arguments:
+
+            origin (unicode|None): The authenticated server_name of the calling server,
+                unless REQUIRE_AUTH is set to False and authentication failed.
+
+            content (unicode|None): decoded json body of the request. None if the
+                request was a GET.
+
+            query (dict[bytes, list[bytes]]): Query params from the request. url-decoded
+                (ie, '+' and '%xx' are decoded) but note that it is *not* utf8-decoded
+                yet.
+
+            **kwargs (dict[unicode, unicode]): the dict mapping keys to path
+                components as specified in the path match regexp.
+
+        Returns:
+            Optional[Tuple[int, object]]: either (response code, response object) to
+                 return a JSON response, or None if the request has already been handled.
+
+        Raises:
+            SynapseError: to return an error code
+
+            Exception: other exceptions will be caught, logged, and a 500 will be
+                returned.
+    """
+
+    PATH = ""  # Overridden in subclasses, the regex to match against the path.
+
+    REQUIRE_AUTH = True
+
+    PREFIX = FEDERATION_V1_PREFIX  # Allows specifying the API version
+
+    RATELIMIT = True  # Whether to rate limit requests or not
+
+    def __init__(
+        self,
+        hs: HomeServer,
+        authenticator: Authenticator,
+        ratelimiter: FederationRateLimiter,
+        server_name: str,
+    ):
+        self.hs = hs
+        self.authenticator = authenticator
+        self.ratelimiter = ratelimiter
+        self.server_name = server_name
+
+    def _wrap(self, func):
+        authenticator = self.authenticator
+        ratelimiter = self.ratelimiter
+
+        @functools.wraps(func)
+        async def new_func(request, *args, **kwargs):
+            """A callback which can be passed to HttpServer.RegisterPaths
+
+            Args:
+                request (twisted.web.http.Request):
+                *args: unused?
+                **kwargs (dict[unicode, unicode]): the dict mapping keys to path
+                    components as specified in the path match regexp.
+
+            Returns:
+                Tuple[int, object]|None: (response code, response object) as returned by
+                    the callback method. None if the request has already been handled.
+            """
+            content = None
+            if request.method in [b"PUT", b"POST"]:
+                # TODO: Handle other method types? other content types?
+                content = parse_json_object_from_request(request)
+
+            try:
+                origin = await authenticator.authenticate_request(request, content)
+            except NoAuthenticationError:
+                origin = None
+                if self.REQUIRE_AUTH:
+                    logger.warning(
+                        "authenticate_request failed: missing authentication"
+                    )
+                    raise
+            except Exception as e:
+                logger.warning("authenticate_request failed: %s", e)
+                raise
+
+            request_tags = {
+                SynapseTags.REQUEST_ID: request.get_request_id(),
+                tags.SPAN_KIND: tags.SPAN_KIND_RPC_SERVER,
+                tags.HTTP_METHOD: request.get_method(),
+                tags.HTTP_URL: request.get_redacted_uri(),
+                tags.PEER_HOST_IPV6: request.getClientIP(),
+                "authenticated_entity": origin,
+                "servlet_name": request.request_metrics.name,
+            }
+
+            # Only accept the span context if the origin is authenticated
+            # and whitelisted
+            if origin and whitelisted_homeserver(origin):
+                scope = start_active_span_from_request(
+                    request, "incoming-federation-request", tags=request_tags
+                )
+            else:
+                scope = start_active_span(
+                    "incoming-federation-request", tags=request_tags
+                )
+
+            with scope:
+                opentracing.inject_response_headers(request.responseHeaders)
+
+                if origin and self.RATELIMIT:
+                    with ratelimiter.ratelimit(origin) as d:
+                        await d
+                        if request._disconnected:
+                            logger.warning(
+                                "client disconnected before we started processing "
+                                "request"
+                            )
+                            return -1, None
+                        response = await func(
+                            origin, content, request.args, *args, **kwargs
+                        )
+                else:
+                    response = await func(
+                        origin, content, request.args, *args, **kwargs
+                    )
+
+            return response
+
+        return new_func
+
+    def register(self, server):
+        pattern = re.compile("^" + self.PREFIX + self.PATH + "$")
+
+        for method in ("GET", "PUT", "POST"):
+            code = getattr(self, "on_%s" % (method), None)
+            if code is None:
+                continue
+
+            server.register_paths(
+                method,
+                (pattern,),
+                self._wrap(code),
+                self.__class__.__name__,
+            )
diff --git a/synapse/federation/transport/server/federation.py b/synapse/federation/transport/server/federation.py
new file mode 100644
index 0000000000..2806337846
--- /dev/null
+++ b/synapse/federation/transport/server/federation.py
@@ -0,0 +1,692 @@
+#  Copyright 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.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+import logging
+from typing import Dict, List, Mapping, Optional, Sequence, Tuple, Type, Union
+
+from typing_extensions import Literal
+
+import synapse
+from synapse.api.errors import Codes, SynapseError
+from synapse.api.room_versions import RoomVersions
+from synapse.api.urls import FEDERATION_UNSTABLE_PREFIX, FEDERATION_V2_PREFIX
+from synapse.federation.transport.server._base import (
+    Authenticator,
+    BaseFederationServlet,
+)
+from synapse.http.servlet import (
+    parse_boolean_from_args,
+    parse_integer_from_args,
+    parse_string_from_args,
+    parse_strings_from_args,
+)
+from synapse.server import HomeServer
+from synapse.types import JsonDict
+from synapse.util.ratelimitutils import FederationRateLimiter
+from synapse.util.versionstring import get_version_string
+
+logger = logging.getLogger(__name__)
+
+
+class BaseFederationServerServlet(BaseFederationServlet):
+    """Abstract base class for federation servlet classes which provides a federation server handler.
+
+    See BaseFederationServlet for more information.
+    """
+
+    def __init__(
+        self,
+        hs: HomeServer,
+        authenticator: Authenticator,
+        ratelimiter: FederationRateLimiter,
+        server_name: str,
+    ):
+        super().__init__(hs, authenticator, ratelimiter, server_name)
+        self.handler = hs.get_federation_server()
+
+
+class FederationSendServlet(BaseFederationServerServlet):
+    PATH = "/send/(?P<transaction_id>[^/]*)/?"
+
+    # We ratelimit manually in the handler as we queue up the requests and we
+    # don't want to fill up the ratelimiter with blocked requests.
+    RATELIMIT = False
+
+    # This is when someone is trying to send us a bunch of data.
+    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:
+            transaction_id: The transaction_id associated with this request. This
+                is *not* None.
+
+        Returns:
+            Tuple of `(code, response)`, where
+            `response` is a python dict to be converted into JSON that is
+            used as the response body.
+        """
+        # Parse the request
+        try:
+            transaction_data = content
+
+            logger.debug("Decoded %s: %s", transaction_id, str(transaction_data))
+
+            logger.info(
+                "Received txn %s from %s. (PDUs: %d, EDUs: %d)",
+                transaction_id,
+                origin,
+                len(transaction_data.get("pdus", [])),
+                len(transaction_data.get("edus", [])),
+            )
+
+        except Exception as e:
+            logger.exception(e)
+            return 400, {"error": "Invalid transaction"}
+
+        code, response = await self.handler.on_incoming_transaction(
+            origin, transaction_id, self.server_name, transaction_data
+        )
+
+        return code, response
+
+
+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: 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)
+
+
+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: 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,
+            parse_string_from_args(query, "event_id", None, required=False),
+        )
+
+
+class FederationStateIdsServlet(BaseFederationServerServlet):
+    PATH = "/state_ids/(?P<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,
+            parse_string_from_args(query, "event_id", None, required=True),
+        )
+
+
+class FederationBackfillServlet(BaseFederationServerServlet):
+    PATH = "/backfill/(?P<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)
+
+        if not limit:
+            return 400, {"error": "Did not include limit param"}
+
+        return await self.handler.on_backfill_request(origin, room_id, versions, limit)
+
+
+class FederationQueryServlet(BaseFederationServerServlet):
+    PATH = "/query/(?P<query_type>[^/]*)"
+
+    # This is when we receive a server-server Query
+    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)
+
+
+class FederationMakeJoinServlet(BaseFederationServerServlet):
+    PATH = "/make_join/(?P<room_id>[^/]*)/(?P<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: The authenticated server_name of the calling server
+
+            content: (GETs don't have bodies)
+
+            query: Query params from the request.
+
+            **kwargs: the dict mapping keys to path components as specified in
+                the path match regexp.
+
+        Returns:
+            Tuple of (response code, response object)
+        """
+        supported_versions = parse_strings_from_args(query, "ver", encoding="utf-8")
+        if supported_versions is None:
+            supported_versions = ["1"]
+
+        result = await self.handler.on_make_join_request(
+            origin, room_id, user_id, supported_versions=supported_versions
+        )
+        return 200, result
+
+
+class FederationMakeLeaveServlet(BaseFederationServerServlet):
+    PATH = "/make_leave/(?P<room_id>[^/]*)/(?P<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]:
+        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: 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):
+    PATH = "/send_leave/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
+
+    PREFIX = FEDERATION_V2_PREFIX
+
+    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: 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"
+        )
+
+        result = await self.handler.on_make_knock_request(
+            origin, room_id, user_id, supported_versions=supported_versions
+        )
+        return 200, result
+
+
+class FederationV1SendKnockServlet(BaseFederationServerServlet):
+    PATH = "/send_knock/(?P<room_id>[^/]*)/(?P<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]:
+        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: 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: 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
+        result = await self.handler.on_send_join_request(origin, content, room_id)
+        return 200, (200, result)
+
+
+class FederationV2SendJoinServlet(BaseFederationServerServlet):
+    PATH = "/send_join/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
+
+    PREFIX = FEDERATION_V2_PREFIX
+
+    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
+        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: 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
+        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, result)
+
+
+class FederationV2InviteServlet(BaseFederationServerServlet):
+    PATH = "/invite/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
+
+    PREFIX = FEDERATION_V2_PREFIX
+
+    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
+
+        room_version = content["room_version"]
+        event = content["event"]
+        invite_room_state = content["invite_room_state"]
+
+        # Synapse expects invite_room_state to be in unsigned, as it is in v1
+        # API
+
+        event.setdefault("unsigned", {})["invite_room_state"] = invite_room_state
+
+        result = await self.handler.on_invite_request(
+            origin, event, room_version_id=room_version
+        )
+        return 200, result
+
+
+class FederationThirdPartyInviteExchangeServlet(BaseFederationServerServlet):
+    PATH = "/exchange_third_party_invite/(?P<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, {}
+
+
+class FederationClientKeysQueryServlet(BaseFederationServerServlet):
+    PATH = "/user/keys/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: 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: str, content: JsonDict, query: Dict[bytes, List[bytes]]
+    ) -> Tuple[int, JsonDict]:
+        response = await self.handler.on_claim_client_keys(origin, content)
+        return 200, response
+
+
+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: 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", [])
+
+        result = await self.handler.on_get_missing_events(
+            origin,
+            room_id=room_id,
+            earliest_events=earliest_events,
+            latest_events=latest_events,
+            limit=limit,
+        )
+
+        return 200, result
+
+
+class On3pidBindServlet(BaseFederationServerServlet):
+    PATH = "/3pid/onbind"
+
+    REQUIRE_AUTH = False
+
+    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"]:
+                try:
+                    if "signed" not in invite or "token" not in invite["signed"]:
+                        message = (
+                            "Rejecting received notification of third-"
+                            "party invite without signed: %s" % (invite,)
+                        )
+                        logger.info(message)
+                        raise SynapseError(400, message)
+                    await self.handler.exchange_third_party_invite(
+                        invite["sender"],
+                        invite["mxid"],
+                        invite["room_id"],
+                        invite["signed"],
+                    )
+                except Exception as e:
+                    last_exception = e
+            if last_exception:
+                raise last_exception
+        return 200, {}
+
+
+class FederationVersionServlet(BaseFederationServlet):
+    PATH = "/version"
+
+    REQUIRE_AUTH = False
+
+    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)}},
+        )
+
+
+class FederationSpaceSummaryServlet(BaseFederationServlet):
+    PREFIX = FEDERATION_UNSTABLE_PREFIX + "/org.matrix.msc2946"
+    PATH = "/spaces/(?P<room_id>[^/]*)"
+
+    def __init__(
+        self,
+        hs: HomeServer,
+        authenticator: Authenticator,
+        ratelimiter: FederationRateLimiter,
+        server_name: str,
+    ):
+        super().__init__(hs, authenticator, ratelimiter, server_name)
+        self.handler = hs.get_space_summary_handler()
+
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Mapping[bytes, Sequence[bytes]],
+        room_id: str,
+    ) -> Tuple[int, JsonDict]:
+        suggested_only = parse_boolean_from_args(query, "suggested_only", default=False)
+        max_rooms_per_space = parse_integer_from_args(query, "max_rooms_per_space")
+
+        exclude_rooms = parse_strings_from_args(query, "exclude_rooms", default=[])
+
+        return 200, await self.handler.federation_space_summary(
+            origin, room_id, suggested_only, max_rooms_per_space, exclude_rooms
+        )
+
+    # TODO When switching to the stable endpoint, remove the POST handler.
+    async def on_POST(
+        self,
+        origin: str,
+        content: JsonDict,
+        query: Mapping[bytes, Sequence[bytes]],
+        room_id: str,
+    ) -> Tuple[int, JsonDict]:
+        suggested_only = content.get("suggested_only", False)
+        if not isinstance(suggested_only, bool):
+            raise SynapseError(
+                400, "'suggested_only' must be a boolean", Codes.BAD_JSON
+            )
+
+        exclude_rooms = content.get("exclude_rooms", [])
+        if not isinstance(exclude_rooms, list) or any(
+            not isinstance(x, str) for x in exclude_rooms
+        ):
+            raise SynapseError(400, "bad value for 'exclude_rooms'", Codes.BAD_JSON)
+
+        max_rooms_per_space = content.get("max_rooms_per_space")
+        if max_rooms_per_space is not None and not isinstance(max_rooms_per_space, int):
+            raise SynapseError(
+                400, "bad value for 'max_rooms_per_space'", Codes.BAD_JSON
+            )
+
+        return 200, await self.handler.federation_space_summary(
+            origin, room_id, suggested_only, max_rooms_per_space, exclude_rooms
+        )
+
+
+class FederationRoomHierarchyServlet(BaseFederationServlet):
+    PREFIX = FEDERATION_UNSTABLE_PREFIX + "/org.matrix.msc2946"
+    PATH = "/hierarchy/(?P<room_id>[^/]*)"
+
+    def __init__(
+        self,
+        hs: HomeServer,
+        authenticator: Authenticator,
+        ratelimiter: FederationRateLimiter,
+        server_name: str,
+    ):
+        super().__init__(hs, authenticator, ratelimiter, server_name)
+        self.handler = hs.get_space_summary_handler()
+
+    async def on_GET(
+        self,
+        origin: str,
+        content: Literal[None],
+        query: Mapping[bytes, Sequence[bytes]],
+        room_id: str,
+    ) -> Tuple[int, JsonDict]:
+        suggested_only = parse_boolean_from_args(query, "suggested_only", default=False)
+        return 200, await self.handler.get_federation_hierarchy(
+            origin, room_id, suggested_only
+        )
+
+
+class RoomComplexityServlet(BaseFederationServlet):
+    """
+    Indicates to other servers how complex (and therefore likely
+    resource-intensive) a public room this server knows about is.
+    """
+
+    PATH = "/rooms/(?P<room_id>[^/]*)/complexity"
+    PREFIX = FEDERATION_UNSTABLE_PREFIX
+
+    def __init__(
+        self,
+        hs: HomeServer,
+        authenticator: Authenticator,
+        ratelimiter: FederationRateLimiter,
+        server_name: str,
+    ):
+        super().__init__(hs, authenticator, ratelimiter, server_name)
+        self._store = self.hs.get_datastore()
+
+    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
+        )
+
+        if not is_public:
+            raise SynapseError(404, "Room not found", errcode=Codes.INVALID_PARAM)
+
+        complexity = await self._store.get_room_complexity(room_id)
+        return 200, complexity
+
+
+FEDERATION_SERVLET_CLASSES: Tuple[Type[BaseFederationServlet], ...] = (
+    FederationSendServlet,
+    FederationEventServlet,
+    FederationStateV1Servlet,
+    FederationStateIdsServlet,
+    FederationBackfillServlet,
+    FederationQueryServlet,
+    FederationMakeJoinServlet,
+    FederationMakeLeaveServlet,
+    FederationEventServlet,
+    FederationV1SendJoinServlet,
+    FederationV2SendJoinServlet,
+    FederationV1SendLeaveServlet,
+    FederationV2SendLeaveServlet,
+    FederationV1InviteServlet,
+    FederationV2InviteServlet,
+    FederationGetMissingEventsServlet,
+    FederationEventAuthServlet,
+    FederationClientKeysQueryServlet,
+    FederationUserDevicesQueryServlet,
+    FederationClientKeysClaimServlet,
+    FederationThirdPartyInviteExchangeServlet,
+    On3pidBindServlet,
+    FederationVersionServlet,
+    RoomComplexityServlet,
+    FederationSpaceSummaryServlet,
+    FederationRoomHierarchyServlet,
+    FederationV1SendKnockServlet,
+    FederationMakeKnockServlet,
+)
diff --git a/synapse/federation/transport/server/groups_local.py b/synapse/federation/transport/server/groups_local.py
new file mode 100644
index 0000000000..a12cd18d58
--- /dev/null
+++ b/synapse/federation/transport/server/groups_local.py
@@ -0,0 +1,113 @@
+#  Copyright 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.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+from typing import Dict, List, Tuple, Type
+
+from synapse.api.errors import SynapseError
+from synapse.federation.transport.server._base import (
+    Authenticator,
+    BaseFederationServlet,
+)
+from synapse.handlers.groups_local import GroupsLocalHandler
+from synapse.server import HomeServer
+from synapse.types import JsonDict, get_domain_from_id
+from synapse.util.ratelimitutils import FederationRateLimiter
+
+
+class BaseGroupsLocalServlet(BaseFederationServlet):
+    """Abstract base class for federation servlet classes which provides a groups local handler.
+
+    See BaseFederationServlet for more information.
+    """
+
+    def __init__(
+        self,
+        hs: HomeServer,
+        authenticator: Authenticator,
+        ratelimiter: FederationRateLimiter,
+        server_name: str,
+    ):
+        super().__init__(hs, authenticator, ratelimiter, server_name)
+        self.handler = hs.get_groups_local_handler()
+
+
+class FederationGroupsLocalInviteServlet(BaseGroupsLocalServlet):
+    """A group server has invited a local user"""
+
+    PATH = "/groups/local/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/invite"
+
+    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")
+
+        assert isinstance(
+            self.handler, GroupsLocalHandler
+        ), "Workers cannot handle group invites."
+
+        new_content = await self.handler.on_invite(group_id, user_id, content)
+
+        return 200, new_content
+
+
+class FederationGroupsRemoveLocalUserServlet(BaseGroupsLocalServlet):
+    """A group server has removed a local user"""
+
+    PATH = "/groups/local/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/remove"
+
+    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")
+
+        assert isinstance(
+            self.handler, GroupsLocalHandler
+        ), "Workers cannot handle group removals."
+
+        await self.handler.user_removed_from_group(group_id, user_id, content)
+
+        return 200, None
+
+
+class FederationGroupsBulkPublicisedServlet(BaseGroupsLocalServlet):
+    """Get roles in a group"""
+
+    PATH = "/get_groups_publicised"
+
+    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
+        )
+
+        return 200, resp
+
+
+GROUP_LOCAL_SERVLET_CLASSES: Tuple[Type[BaseFederationServlet], ...] = (
+    FederationGroupsLocalInviteServlet,
+    FederationGroupsRemoveLocalUserServlet,
+    FederationGroupsBulkPublicisedServlet,
+)
diff --git a/synapse/federation/transport/server/groups_server.py b/synapse/federation/transport/server/groups_server.py
new file mode 100644
index 0000000000..b30e92a5eb
--- /dev/null
+++ b/synapse/federation/transport/server/groups_server.py
@@ -0,0 +1,753 @@
+#  Copyright 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.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+from typing import Dict, List, Tuple, Type
+
+from typing_extensions import Literal
+
+from synapse.api.constants import MAX_GROUP_CATEGORYID_LENGTH, MAX_GROUP_ROLEID_LENGTH
+from synapse.api.errors import Codes, SynapseError
+from synapse.federation.transport.server._base import (
+    Authenticator,
+    BaseFederationServlet,
+)
+from synapse.http.servlet import parse_string_from_args
+from synapse.server import HomeServer
+from synapse.types import JsonDict, get_domain_from_id
+from synapse.util.ratelimitutils import FederationRateLimiter
+
+
+class BaseGroupsServerServlet(BaseFederationServlet):
+    """Abstract base class for federation servlet classes which provides a groups server handler.
+
+    See BaseFederationServlet for more information.
+    """
+
+    def __init__(
+        self,
+        hs: HomeServer,
+        authenticator: Authenticator,
+        ratelimiter: FederationRateLimiter,
+        server_name: str,
+    ):
+        super().__init__(hs, authenticator, ratelimiter, server_name)
+        self.handler = hs.get_groups_server_handler()
+
+
+class FederationGroupsProfileServlet(BaseGroupsServerServlet):
+    """Get/set the basic profile of a group on behalf of a user"""
+
+    PATH = "/groups/(?P<group_id>[^/]*)/profile"
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        new_content = await self.handler.get_group_profile(group_id, requester_user_id)
+
+        return 200, new_content
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        new_content = await self.handler.update_group_profile(
+            group_id, requester_user_id, content
+        )
+
+        return 200, new_content
+
+
+class FederationGroupsSummaryServlet(BaseGroupsServerServlet):
+    PATH = "/groups/(?P<group_id>[^/]*)/summary"
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        new_content = await self.handler.get_group_summary(group_id, requester_user_id)
+
+        return 200, new_content
+
+
+class FederationGroupsRoomsServlet(BaseGroupsServerServlet):
+    """Get the rooms in a group on behalf of a user"""
+
+    PATH = "/groups/(?P<group_id>[^/]*)/rooms"
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        new_content = await self.handler.get_rooms_in_group(group_id, requester_user_id)
+
+        return 200, new_content
+
+
+class FederationGroupsAddRoomsServlet(BaseGroupsServerServlet):
+    """Add/remove room from group"""
+
+    PATH = "/groups/(?P<group_id>[^/]*)/room/(?P<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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        new_content = await self.handler.add_room_to_group(
+            group_id, requester_user_id, room_id, content
+        )
+
+        return 200, new_content
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        new_content = await self.handler.remove_room_from_group(
+            group_id, requester_user_id, room_id
+        )
+
+        return 200, new_content
+
+
+class FederationGroupsAddRoomsConfigServlet(BaseGroupsServerServlet):
+    """Update room config in group"""
+
+    PATH = (
+        "/groups/(?P<group_id>[^/]*)/room/(?P<room_id>[^/]*)"
+        "/config/(?P<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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        result = await self.handler.update_room_in_group(
+            group_id, requester_user_id, room_id, config_key, content
+        )
+
+        return 200, result
+
+
+class FederationGroupsUsersServlet(BaseGroupsServerServlet):
+    """Get the users in a group on behalf of a user"""
+
+    PATH = "/groups/(?P<group_id>[^/]*)/users"
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        new_content = await self.handler.get_users_in_group(group_id, requester_user_id)
+
+        return 200, new_content
+
+
+class FederationGroupsInvitedUsersServlet(BaseGroupsServerServlet):
+    """Get the users that have been invited to a group"""
+
+    PATH = "/groups/(?P<group_id>[^/]*)/invited_users"
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        new_content = await self.handler.get_invited_users_in_group(
+            group_id, requester_user_id
+        )
+
+        return 200, new_content
+
+
+class FederationGroupsInviteServlet(BaseGroupsServerServlet):
+    """Ask a group server to invite someone to the group"""
+
+    PATH = "/groups/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/invite"
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        new_content = await self.handler.invite_to_group(
+            group_id, user_id, requester_user_id, content
+        )
+
+        return 200, new_content
+
+
+class FederationGroupsAcceptInviteServlet(BaseGroupsServerServlet):
+    """Accept an invitation from the group server"""
+
+    PATH = "/groups/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/accept_invite"
+
+    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")
+
+        new_content = await self.handler.accept_invite(group_id, user_id, content)
+
+        return 200, new_content
+
+
+class FederationGroupsJoinServlet(BaseGroupsServerServlet):
+    """Attempt to join a group"""
+
+    PATH = "/groups/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/join"
+
+    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")
+
+        new_content = await self.handler.join_group(group_id, user_id, content)
+
+        return 200, new_content
+
+
+class FederationGroupsRemoveUserServlet(BaseGroupsServerServlet):
+    """Leave or kick a user from the group"""
+
+    PATH = "/groups/(?P<group_id>[^/]*)/users/(?P<user_id>[^/]*)/remove"
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        new_content = await self.handler.remove_user_from_group(
+            group_id, user_id, requester_user_id, content
+        )
+
+        return 200, new_content
+
+
+class FederationGroupsSummaryRoomsServlet(BaseGroupsServerServlet):
+    """Add/remove a room from the group summary, with optional category.
+
+    Matches both:
+        - /groups/:group/summary/rooms/:room_id
+        - /groups/:group/summary/categories/:category/rooms/:room_id
+    """
+
+    PATH = (
+        "/groups/(?P<group_id>[^/]*)/summary"
+        "(/categories/(?P<category_id>[^/]+))?"
+        "/rooms/(?P<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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        if category_id == "":
+            raise SynapseError(
+                400, "category_id cannot be empty string", Codes.INVALID_PARAM
+            )
+
+        if len(category_id) > MAX_GROUP_CATEGORYID_LENGTH:
+            raise SynapseError(
+                400,
+                "category_id may not be longer than %s characters"
+                % (MAX_GROUP_CATEGORYID_LENGTH,),
+                Codes.INVALID_PARAM,
+            )
+
+        resp = await self.handler.update_group_summary_room(
+            group_id,
+            requester_user_id,
+            room_id=room_id,
+            category_id=category_id,
+            content=content,
+        )
+
+        return 200, resp
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        if category_id == "":
+            raise SynapseError(400, "category_id cannot be empty string")
+
+        resp = await self.handler.delete_group_summary_room(
+            group_id, requester_user_id, room_id=room_id, category_id=category_id
+        )
+
+        return 200, resp
+
+
+class FederationGroupsCategoriesServlet(BaseGroupsServerServlet):
+    """Get all categories for a group"""
+
+    PATH = "/groups/(?P<group_id>[^/]*)/categories/?"
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        resp = await self.handler.get_group_categories(group_id, requester_user_id)
+
+        return 200, resp
+
+
+class FederationGroupsCategoryServlet(BaseGroupsServerServlet):
+    """Add/remove/get a category in a group"""
+
+    PATH = "/groups/(?P<group_id>[^/]*)/categories/(?P<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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        resp = await self.handler.get_group_category(
+            group_id, requester_user_id, category_id
+        )
+
+        return 200, resp
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        if category_id == "":
+            raise SynapseError(400, "category_id cannot be empty string")
+
+        if len(category_id) > MAX_GROUP_CATEGORYID_LENGTH:
+            raise SynapseError(
+                400,
+                "category_id may not be longer than %s characters"
+                % (MAX_GROUP_CATEGORYID_LENGTH,),
+                Codes.INVALID_PARAM,
+            )
+
+        resp = await self.handler.upsert_group_category(
+            group_id, requester_user_id, category_id, content
+        )
+
+        return 200, resp
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        if category_id == "":
+            raise SynapseError(400, "category_id cannot be empty string")
+
+        resp = await self.handler.delete_group_category(
+            group_id, requester_user_id, category_id
+        )
+
+        return 200, resp
+
+
+class FederationGroupsRolesServlet(BaseGroupsServerServlet):
+    """Get roles in a group"""
+
+    PATH = "/groups/(?P<group_id>[^/]*)/roles/?"
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        resp = await self.handler.get_group_roles(group_id, requester_user_id)
+
+        return 200, resp
+
+
+class FederationGroupsRoleServlet(BaseGroupsServerServlet):
+    """Add/remove/get a role in a group"""
+
+    PATH = "/groups/(?P<group_id>[^/]*)/roles/(?P<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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        resp = await self.handler.get_group_role(group_id, requester_user_id, role_id)
+
+        return 200, resp
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        if role_id == "":
+            raise SynapseError(
+                400, "role_id cannot be empty string", Codes.INVALID_PARAM
+            )
+
+        if len(role_id) > MAX_GROUP_ROLEID_LENGTH:
+            raise SynapseError(
+                400,
+                "role_id may not be longer than %s characters"
+                % (MAX_GROUP_ROLEID_LENGTH,),
+                Codes.INVALID_PARAM,
+            )
+
+        resp = await self.handler.update_group_role(
+            group_id, requester_user_id, role_id, content
+        )
+
+        return 200, resp
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        if role_id == "":
+            raise SynapseError(400, "role_id cannot be empty string")
+
+        resp = await self.handler.delete_group_role(
+            group_id, requester_user_id, role_id
+        )
+
+        return 200, resp
+
+
+class FederationGroupsSummaryUsersServlet(BaseGroupsServerServlet):
+    """Add/remove a user from the group summary, with optional role.
+
+    Matches both:
+        - /groups/:group/summary/users/:user_id
+        - /groups/:group/summary/roles/:role/users/:user_id
+    """
+
+    PATH = (
+        "/groups/(?P<group_id>[^/]*)/summary"
+        "(/roles/(?P<role_id>[^/]+))?"
+        "/users/(?P<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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        if role_id == "":
+            raise SynapseError(400, "role_id cannot be empty string")
+
+        if len(role_id) > MAX_GROUP_ROLEID_LENGTH:
+            raise SynapseError(
+                400,
+                "role_id may not be longer than %s characters"
+                % (MAX_GROUP_ROLEID_LENGTH,),
+                Codes.INVALID_PARAM,
+            )
+
+        resp = await self.handler.update_group_summary_user(
+            group_id,
+            requester_user_id,
+            user_id=user_id,
+            role_id=role_id,
+            content=content,
+        )
+
+        return 200, resp
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        if role_id == "":
+            raise SynapseError(400, "role_id cannot be empty string")
+
+        resp = await self.handler.delete_group_summary_user(
+            group_id, requester_user_id, user_id=user_id, role_id=role_id
+        )
+
+        return 200, resp
+
+
+class FederationGroupsSettingJoinPolicyServlet(BaseGroupsServerServlet):
+    """Sets whether a group is joinable without an invite or knock"""
+
+    PATH = "/groups/(?P<group_id>[^/]*)/settings/m.join_policy"
+
+    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", required=True
+        )
+        if get_domain_from_id(requester_user_id) != origin:
+            raise SynapseError(403, "requester_user_id doesn't match origin")
+
+        new_content = await self.handler.set_group_join_policy(
+            group_id, requester_user_id, content
+        )
+
+        return 200, new_content
+
+
+GROUP_SERVER_SERVLET_CLASSES: Tuple[Type[BaseFederationServlet], ...] = (
+    FederationGroupsProfileServlet,
+    FederationGroupsSummaryServlet,
+    FederationGroupsRoomsServlet,
+    FederationGroupsUsersServlet,
+    FederationGroupsInvitedUsersServlet,
+    FederationGroupsInviteServlet,
+    FederationGroupsAcceptInviteServlet,
+    FederationGroupsJoinServlet,
+    FederationGroupsRemoveUserServlet,
+    FederationGroupsSummaryRoomsServlet,
+    FederationGroupsCategoriesServlet,
+    FederationGroupsCategoryServlet,
+    FederationGroupsRolesServlet,
+    FederationGroupsRoleServlet,
+    FederationGroupsSummaryUsersServlet,
+    FederationGroupsAddRoomsServlet,
+    FederationGroupsAddRoomsConfigServlet,
+    FederationGroupsSettingJoinPolicyServlet,
+)