| diff --git a/synapse/__init__.py b/synapse/__init__.py
index 119359be68..a7d2008e82 100644
--- a/synapse/__init__.py
+++ b/synapse/__init__.py
@@ -35,4 +35,4 @@ try:
 except ImportError:
     pass
 
-__version__ = "1.0.0"
+__version__ = "1.1.0rc1"
diff --git a/synapse/config/saml2_config.py b/synapse/config/saml2_config.py
 index 872a1ba934..6a8161547a 100644
--- a/synapse/config/saml2_config.py
+++ b/synapse/config/saml2_config.py
@@ -12,6 +12,7 @@
 # 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 synapse.python_dependencies import DependencyException, check_requirements
 
 from ._base import Config, ConfigError
 
@@ -25,6 +26,11 @@ class SAML2Config(Config):
         if not saml2_config or not saml2_config.get("enabled", True):
             return
 
+        try:
+            check_requirements("saml2")
+        except DependencyException as e:
+            raise ConfigError(e.message)
+
         self.saml2_enabled = True
 
         import saml2.config
@@ -37,6 +43,11 @@ class SAML2Config(Config):
         if config_path is not None:
             self.saml2_sp_config.load_file(config_path)
 
+        # session lifetime: in milliseconds
+        self.saml2_session_lifetime = self.parse_duration(
+            saml2_config.get("saml_session_lifetime", "5m")
+        )
+
     def _default_saml_config_dict(self):
         import saml2
 
@@ -72,6 +83,12 @@ class SAML2Config(Config):
         # so it is not normally necessary to specify them unless you need to
         # override them.
         #
+        # Once SAML support is enabled, a metadata file will be exposed at
+        # https://<server>:<port>/_matrix/saml2/metadata.xml, which you may be able to
+        # use to configure your SAML IdP with. Alternatively, you can manually configure
+        # the IdP to use an ACS location of
+        # https://<server>:<port>/_matrix/saml2/authn_response.
+        #
         #saml2_config:
         #  sp_config:
         #    # point this to the IdP's metadata. You can use either a local file or
@@ -81,7 +98,15 @@ class SAML2Config(Config):
         #      remote:
         #        - url: https://our_idp/metadata.xml
         #
-        #    # The rest of sp_config is just used to generate our metadata xml, and you
+        #    # By default, the user has to go to our login page first. If you'd like to
+        #    # allow IdP-initiated login, set 'allow_unsolicited: True' in a
+        #    # 'service.sp' section:
+        #    #
+        #    #service:
+        #    #  sp:
+        #    #    allow_unsolicited: True
+        #
+        #    # The examples below are just used to generate our metadata xml, and you
         #    # may well not need it, depending on your setup. Alternatively you
         #    # may need a whole lot more detail - see the pysaml2 docs!
         #
@@ -104,6 +129,12 @@ class SAML2Config(Config):
         #  # separate pysaml2 configuration file:
         #  #
         #  config_path: "%(config_dir_path)s/sp_conf.py"
+        #
+        #  # the lifetime of a SAML session. This defines how long a user has to
+        #  # complete the authentication process, if allow_unsolicited is unset.
+        #  # The default is 5 minutes.
+        #  #
+        #  # saml_session_lifetime: 5m
         """ % {
             "config_dir_path": config_dir_path
         }
diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py
 index 5204073a38..c80dc2eba0 100644
--- a/synapse/handlers/presence.py
+++ b/synapse/handlers/presence.py
@@ -1017,11 +1017,28 @@ class PresenceEventSource(object):
             if from_key is not None:
                 from_key = int(from_key)
 
+            max_token = self.store.get_current_presence_token()
+            if from_key == max_token:
+                # This is necessary as due to the way stream ID generators work
+                # we may get updates that have a stream ID greater than the max
+                # token (e.g. max_token is N but stream generator may return
+                # results for N+2, due to N+1 not having finished being
+                # persisted yet).
+                #
+                # This is usually fine, as it just means that we may send down
+                # some presence updates multiple times. However, we need to be
+                # careful that the sync stream either actually does make some
+                # progress or doesn't return, otherwise clients will end up
+                # tight looping calling /sync due to it immediately returning
+                # the same token repeatedly.
+                #
+                # Hence this guard where we just return nothing so that the sync
+                # doesn't return. C.f. #5503.
+                defer.returnValue(([], max_token))
+
             presence = self.get_presence_handler()
             stream_change_cache = self.store.presence_stream_cache
 
-            max_token = self.store.get_current_presence_token()
-
             users_interested_in = yield self._get_interested_in(user, explicit_room_id)
 
             user_ids_changed = set()
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
 index 7014e9e02f..c128ef8076 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -843,6 +843,7 @@ class RoomMemberHandler(object):
                 "sender": user.to_string(),
                 "state_key": token,
             },
+            ratelimit=False,
             txn_id=txn_id,
         )
 
diff --git a/synapse/handlers/saml_handler.py b/synapse/handlers/saml_handler.py
new file mode 100644
 index 0000000000..a1ce6929cf
--- /dev/null
+++ b/synapse/handlers/saml_handler.py
@@ -0,0 +1,123 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 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
+
+import attr
+import saml2
+from saml2.client import Saml2Client
+
+from synapse.api.errors import SynapseError
+from synapse.http.servlet import parse_string
+from synapse.rest.client.v1.login import SSOAuthHandler
+
+logger = logging.getLogger(__name__)
+
+
+class SamlHandler:
+    def __init__(self, hs):
+        self._saml_client = Saml2Client(hs.config.saml2_sp_config)
+        self._sso_auth_handler = SSOAuthHandler(hs)
+
+        # a map from saml session id to Saml2SessionData object
+        self._outstanding_requests_dict = {}
+
+        self._clock = hs.get_clock()
+        self._saml2_session_lifetime = hs.config.saml2_session_lifetime
+
+    def handle_redirect_request(self, client_redirect_url):
+        """Handle an incoming request to /login/sso/redirect
+
+        Args:
+            client_redirect_url (bytes): the URL that we should redirect the
+                client to when everything is done
+
+        Returns:
+            bytes: URL to redirect to
+        """
+        reqid, info = self._saml_client.prepare_for_authenticate(
+            relay_state=client_redirect_url
+        )
+
+        now = self._clock.time_msec()
+        self._outstanding_requests_dict[reqid] = Saml2SessionData(creation_time=now)
+
+        for key, value in info["headers"]:
+            if key == "Location":
+                return value
+
+        # this shouldn't happen!
+        raise Exception("prepare_for_authenticate didn't return a Location header")
+
+    def handle_saml_response(self, request):
+        """Handle an incoming request to /_matrix/saml2/authn_response
+
+        Args:
+            request (SynapseRequest): the incoming request from the browser. We'll
+                respond to it with a redirect.
+
+        Returns:
+            Deferred[none]: Completes once we have handled the request.
+        """
+        resp_bytes = parse_string(request, "SAMLResponse", required=True)
+        relay_state = parse_string(request, "RelayState", required=True)
+
+        # expire outstanding sessions before parse_authn_request_response checks
+        # the dict.
+        self.expire_sessions()
+
+        try:
+            saml2_auth = self._saml_client.parse_authn_request_response(
+                resp_bytes,
+                saml2.BINDING_HTTP_POST,
+                outstanding=self._outstanding_requests_dict,
+            )
+        except Exception as e:
+            logger.warning("Exception parsing SAML2 response: %s", e)
+            raise SynapseError(400, "Unable to parse SAML2 response: %s" % (e,))
+
+        if saml2_auth.not_signed:
+            logger.warning("SAML2 response was not signed")
+            raise SynapseError(400, "SAML2 response was not signed")
+
+        if "uid" not in saml2_auth.ava:
+            logger.warning("SAML2 response lacks a 'uid' attestation")
+            raise SynapseError(400, "uid not in SAML2 response")
+
+        self._outstanding_requests_dict.pop(saml2_auth.in_response_to, None)
+
+        username = saml2_auth.ava["uid"][0]
+        displayName = saml2_auth.ava.get("displayName", [None])[0]
+
+        return self._sso_auth_handler.on_successful_auth(
+            username, request, relay_state, user_display_name=displayName
+        )
+
+    def expire_sessions(self):
+        expire_before = self._clock.time_msec() - self._saml2_session_lifetime
+        to_expire = set()
+        for reqid, data in self._outstanding_requests_dict.items():
+            if data.creation_time < expire_before:
+                to_expire.add(reqid)
+        for reqid in to_expire:
+            logger.debug("Expiring session id %s", reqid)
+            del self._outstanding_requests_dict[reqid]
+
+
+@attr.s
+class Saml2SessionData:
+    """Data we track about SAML2 sessions"""
+
+    # time the session was created, in milliseconds
+    creation_time = attr.ib()
diff --git a/synapse/http/server.py b/synapse/http/server.py
 index 6fd13e87d1..f067c163c1 100644
--- a/synapse/http/server.py
+++ b/synapse/http/server.py
@@ -16,10 +16,11 @@
 
 import cgi
 import collections
+import http.client
 import logging
-
-from six import PY3
-from six.moves import http_client, urllib
+import types
+import urllib
+from io import BytesIO
 
 from canonicaljson import encode_canonical_json, encode_pretty_printed_json, json
 
@@ -41,11 +42,6 @@ from synapse.api.errors import (
 from synapse.util.caches import intern_dict
 from synapse.util.logcontext import preserve_fn
 
-if PY3:
-    from io import BytesIO
-else:
-    from cStringIO import StringIO as BytesIO
-
 logger = logging.getLogger(__name__)
 
 HTML_ERROR_TEMPLATE = """<!DOCTYPE html>
@@ -75,10 +71,9 @@ def wrap_json_request_handler(h):
     deferred fails with any other type of error we send a 500 reponse.
     """
 
-    @defer.inlineCallbacks
-    def wrapped_request_handler(self, request):
+    async def wrapped_request_handler(self, request):
         try:
-            yield h(self, request)
+            await h(self, request)
         except SynapseError as e:
             code = e.code
             logger.info("%s SynapseError: %s - %s", request, code, e.msg)
@@ -142,10 +137,12 @@ def wrap_html_request_handler(h):
     where "request" must be a SynapseRequest.
     """
 
-    def wrapped_request_handler(self, request):
-        d = defer.maybeDeferred(h, self, request)
-        d.addErrback(_return_html_error, request)
-        return d
+    async def wrapped_request_handler(self, request):
+        try:
+            return await h(self, request)
+        except Exception:
+            f = failure.Failure()
+            return _return_html_error(f, request)
 
     return wrap_async_request_handler(wrapped_request_handler)
 
@@ -171,7 +168,7 @@ def _return_html_error(f, request):
                 exc_info=(f.type, f.value, f.getTracebackObject()),
             )
     else:
-        code = http_client.INTERNAL_SERVER_ERROR
+        code = http.client.INTERNAL_SERVER_ERROR
         msg = "Internal server error"
 
         logger.error(
@@ -201,10 +198,9 @@ def wrap_async_request_handler(h):
     logged until the deferred completes.
     """
 
-    @defer.inlineCallbacks
-    def wrapped_async_request_handler(self, request):
+    async def wrapped_async_request_handler(self, request):
         with request.processing():
-            yield h(self, request)
+            await h(self, request)
 
     # we need to preserve_fn here, because the synchronous render method won't yield for
     # us (obviously)
@@ -270,12 +266,11 @@ class JsonResource(HttpServer, resource.Resource):
     def render(self, request):
         """ This gets called by twisted every time someone sends us a request.
         """
-        self._async_render(request)
+        defer.ensureDeferred(self._async_render(request))
         return NOT_DONE_YET
 
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def _async_render(self, request):
+    async def _async_render(self, request):
         """ This gets called from render() every time someone sends us a request.
             This checks if anyone has registered a callback for that method and
             path.
@@ -292,26 +287,19 @@ class JsonResource(HttpServer, resource.Resource):
         # Now trigger the callback. If it returns a response, we send it
         # here. If it throws an exception, that is handled by the wrapper
         # installed by @request_handler.
-
-        def _unquote(s):
-            if PY3:
-                # On Python 3, unquote is unicode -> unicode
-                return urllib.parse.unquote(s)
-            else:
-                # On Python 2, unquote is bytes -> bytes We need to encode the
-                # URL again (as it was decoded by _get_handler_for request), as
-                # ASCII because it's a URL, and then decode it to get the UTF-8
-                # characters that were quoted.
-                return urllib.parse.unquote(s.encode("ascii")).decode("utf8")
-
         kwargs = intern_dict(
             {
-                name: _unquote(value) if value else value
+                name: urllib.parse.unquote(value) if value else value
                 for name, value in group_dict.items()
             }
         )
 
-        callback_return = yield callback(request, **kwargs)
+        callback_return = callback(request, **kwargs)
+
+        # Is it synchronous? We'll allow this for now.
+        if isinstance(callback_return, (defer.Deferred, types.CoroutineType)):
+            callback_return = await callback_return
+
         if callback_return is not None:
             code, response = callback_return
             self._send_response(request, code, response)
@@ -360,6 +348,23 @@ class JsonResource(HttpServer, resource.Resource):
         )
 
 
+class DirectServeResource(resource.Resource):
+    def render(self, request):
+        """
+        Render the request, using an asynchronous render handler if it exists.
+        """
+        render_callback_name = "_async_render_" + request.method.decode("ascii")
+
+        if hasattr(self, render_callback_name):
+            # Call the handler
+            callback = getattr(self, render_callback_name)
+            defer.ensureDeferred(callback(request))
+
+            return NOT_DONE_YET
+        else:
+            super().render(request)
+
+
 def _options_handler(request):
     """Request handler for OPTIONS requests
 
diff --git a/synapse/metrics/__init__.py b/synapse/metrics/__init__.py
 index 1f30179b51..eaf0aaa86e 100644
--- a/synapse/metrics/__init__.py
+++ b/synapse/metrics/__init__.py
@@ -437,7 +437,10 @@ def runUntilCurrentTimer(func):
         counts = gc.get_count()
         for i in (2, 1, 0):
             if threshold[i] < counts[i]:
-                logger.info("Collecting gc %d", i)
+                if i == 0:
+                    logger.debug("Collecting gc %d", i)
+                else:
+                    logger.info("Collecting gc %d", i)
 
                 start = time.time()
                 unreachable = gc.collect(i)
diff --git a/synapse/rest/client/v1/login.py b/synapse/rest/client/v1/login.py
 index ede6bc8b1e..f961178235 100644
--- a/synapse/rest/client/v1/login.py
+++ b/synapse/rest/client/v1/login.py
@@ -86,6 +86,7 @@ class LoginRestServlet(RestServlet):
         self.jwt_enabled = hs.config.jwt_enabled
         self.jwt_secret = hs.config.jwt_secret
         self.jwt_algorithm = hs.config.jwt_algorithm
+        self.saml2_enabled = hs.config.saml2_enabled
         self.cas_enabled = hs.config.cas_enabled
         self.auth_handler = self.hs.get_auth_handler()
         self.registration_handler = hs.get_registration_handler()
@@ -97,6 +98,9 @@ class LoginRestServlet(RestServlet):
         flows = []
         if self.jwt_enabled:
             flows.append({"type": LoginRestServlet.JWT_TYPE})
+        if self.saml2_enabled:
+            flows.append({"type": LoginRestServlet.SSO_TYPE})
+            flows.append({"type": LoginRestServlet.TOKEN_TYPE})
         if self.cas_enabled:
             flows.append({"type": LoginRestServlet.SSO_TYPE})
 
@@ -319,12 +323,12 @@ class LoginRestServlet(RestServlet):
             raise LoginError(401, "Invalid JWT", errcode=Codes.UNAUTHORIZED)
 
         user_id = UserID(user, self.hs.hostname).to_string()
+        device_id = login_submission.get("device_id")
+        initial_display_name = login_submission.get("initial_device_display_name")
 
         auth_handler = self.auth_handler
         registered_user_id = yield auth_handler.check_user_exists(user_id)
         if registered_user_id:
-            device_id = login_submission.get("device_id")
-            initial_display_name = login_submission.get("initial_device_display_name")
             device_id, access_token = yield self.registration_handler.register_device(
                 registered_user_id, device_id, initial_display_name
             )
@@ -338,11 +342,8 @@ class LoginRestServlet(RestServlet):
             user_id, access_token = (
                 yield self.registration_handler.register(localpart=user)
             )
-
-            device_id = login_submission.get("device_id")
-            initial_display_name = login_submission.get("initial_device_display_name")
             device_id, access_token = yield self.registration_handler.register_device(
-                registered_user_id, device_id, initial_display_name
+                user_id, device_id, initial_display_name
             )
 
             result = {
@@ -354,27 +355,49 @@ class LoginRestServlet(RestServlet):
         defer.returnValue(result)
 
 
-class CasRedirectServlet(RestServlet):
+class BaseSSORedirectServlet(RestServlet):
+    """Common base class for /login/sso/redirect impls"""
+
     PATTERNS = client_patterns("/login/(cas|sso)/redirect", v1=True)
 
+    def on_GET(self, request):
+        args = request.args
+        if b"redirectUrl" not in args:
+            return 400, "Redirect URL not specified for SSO auth"
+        client_redirect_url = args[b"redirectUrl"][0]
+        sso_url = self.get_sso_url(client_redirect_url)
+        request.redirect(sso_url)
+        finish_request(request)
+
+    def get_sso_url(self, client_redirect_url):
+        """Get the URL to redirect to, to perform SSO auth
+
+        Args:
+            client_redirect_url (bytes): the URL that we should redirect the
+                client to when everything is done
+
+        Returns:
+            bytes: URL to redirect to
+        """
+        # to be implemented by subclasses
+        raise NotImplementedError()
+
+
+class CasRedirectServlet(BaseSSORedirectServlet):
     def __init__(self, hs):
         super(CasRedirectServlet, self).__init__()
         self.cas_server_url = hs.config.cas_server_url.encode("ascii")
         self.cas_service_url = hs.config.cas_service_url.encode("ascii")
 
-    def on_GET(self, request):
-        args = request.args
-        if b"redirectUrl" not in args:
-            return (400, "Redirect URL not specified for CAS auth")
+    def get_sso_url(self, client_redirect_url):
         client_redirect_url_param = urllib.parse.urlencode(
-            {b"redirectUrl": args[b"redirectUrl"][0]}
+            {b"redirectUrl": client_redirect_url}
         ).encode("ascii")
         hs_redirect_url = self.cas_service_url + b"/_matrix/client/r0/login/cas/ticket"
         service_param = urllib.parse.urlencode(
             {b"service": b"%s?%s" % (hs_redirect_url, client_redirect_url_param)}
         ).encode("ascii")
-        request.redirect(b"%s/login?%s" % (self.cas_server_url, service_param))
-        finish_request(request)
+        return b"%s/login?%s" % (self.cas_server_url, service_param)
 
 
 class CasTicketServlet(RestServlet):
@@ -457,6 +480,16 @@ class CasTicketServlet(RestServlet):
         return user, attributes
 
 
+class SAMLRedirectServlet(BaseSSORedirectServlet):
+    PATTERNS = client_patterns("/login/sso/redirect", v1=True)
+
+    def __init__(self, hs):
+        self._saml_handler = hs.get_saml_handler()
+
+    def get_sso_url(self, client_redirect_url):
+        return self._saml_handler.handle_redirect_request(client_redirect_url)
+
+
 class SSOAuthHandler(object):
     """
     Utility class for Resources and Servlets which handle the response from a SSO
@@ -532,3 +565,5 @@ def register_servlets(hs, http_server):
     if hs.config.cas_enabled:
         CasRedirectServlet(hs).register(http_server)
         CasTicketServlet(hs).register(http_server)
+    elif hs.config.saml2_enabled:
+        SAMLRedirectServlet(hs).register(http_server)
diff --git a/synapse/rest/consent/consent_resource.py b/synapse/rest/consent/consent_resource.py
 index 9a32892d8b..1ddf9997ff 100644
--- a/synapse/rest/consent/consent_resource.py
+++ b/synapse/rest/consent/consent_resource.py
@@ -24,12 +24,14 @@ import jinja2
 from jinja2 import TemplateNotFound
 
 from twisted.internet import defer
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
 
 from synapse.api.errors import NotFoundError, StoreError, SynapseError
 from synapse.config import ConfigError
-from synapse.http.server import finish_request, wrap_html_request_handler
+from synapse.http.server import (
+    DirectServeResource,
+    finish_request,
+    wrap_html_request_handler,
+)
 from synapse.http.servlet import parse_string
 from synapse.types import UserID
 
@@ -47,7 +49,7 @@ else:
         return a == b
 
 
-class ConsentResource(Resource):
+class ConsentResource(DirectServeResource):
     """A twisted Resource to display a privacy policy and gather consent to it
 
     When accessed via GET, returns the privacy policy via a template.
@@ -87,7 +89,7 @@ class ConsentResource(Resource):
         Args:
             hs (synapse.server.HomeServer): homeserver
         """
-        Resource.__init__(self)
+        super().__init__()
 
         self.hs = hs
         self.store = hs.get_datastore()
@@ -118,18 +120,12 @@ class ConsentResource(Resource):
 
         self._hmac_secret = hs.config.form_secret.encode("utf-8")
 
-    def render_GET(self, request):
-        self._async_render_GET(request)
-        return NOT_DONE_YET
-
     @wrap_html_request_handler
-    @defer.inlineCallbacks
-    def _async_render_GET(self, request):
+    async def _async_render_GET(self, request):
         """
         Args:
             request (twisted.web.http.Request):
         """
-
         version = parse_string(request, "v", default=self._default_consent_version)
         username = parse_string(request, "u", required=False, default="")
         userhmac = None
@@ -145,7 +141,7 @@ class ConsentResource(Resource):
             else:
                 qualified_user_id = UserID(username, self.hs.hostname).to_string()
 
-            u = yield self.store.get_user_by_id(qualified_user_id)
+            u = await defer.maybeDeferred(self.store.get_user_by_id, qualified_user_id)
             if u is None:
                 raise NotFoundError("Unknown user")
 
@@ -165,13 +161,8 @@ class ConsentResource(Resource):
         except TemplateNotFound:
             raise NotFoundError("Unknown policy version")
 
-    def render_POST(self, request):
-        self._async_render_POST(request)
-        return NOT_DONE_YET
-
     @wrap_html_request_handler
-    @defer.inlineCallbacks
-    def _async_render_POST(self, request):
+    async def _async_render_POST(self, request):
         """
         Args:
             request (twisted.web.http.Request):
@@ -188,12 +179,12 @@ class ConsentResource(Resource):
             qualified_user_id = UserID(username, self.hs.hostname).to_string()
 
         try:
-            yield self.store.user_set_consent_version(qualified_user_id, version)
+            await self.store.user_set_consent_version(qualified_user_id, version)
         except StoreError as e:
             if e.code != 404:
                 raise
             raise NotFoundError("Unknown user")
-        yield self.registration_handler.post_consent_actions(qualified_user_id)
+        await self.registration_handler.post_consent_actions(qualified_user_id)
 
         try:
             self._render_template(request, "success.html")
diff --git a/synapse/rest/key/v2/remote_key_resource.py b/synapse/rest/key/v2/remote_key_resource.py
 index ec8b9d7269..031a316693 100644
--- a/synapse/rest/key/v2/remote_key_resource.py
+++ b/synapse/rest/key/v2/remote_key_resource.py
@@ -16,18 +16,20 @@ import logging
 from io import BytesIO
 
 from twisted.internet import defer
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
 
 from synapse.api.errors import Codes, SynapseError
 from synapse.crypto.keyring import ServerKeyFetcher
-from synapse.http.server import respond_with_json_bytes, wrap_json_request_handler
+from synapse.http.server import (
+    DirectServeResource,
+    respond_with_json_bytes,
+    wrap_json_request_handler,
+)
 from synapse.http.servlet import parse_integer, parse_json_object_from_request
 
 logger = logging.getLogger(__name__)
 
 
-class RemoteKey(Resource):
+class RemoteKey(DirectServeResource):
     """HTTP resource for retreiving the TLS certificate and NACL signature
     verification keys for a collection of servers. Checks that the reported
     X.509 TLS certificate matches the one used in the HTTPS connection. Checks
@@ -94,13 +96,8 @@ class RemoteKey(Resource):
         self.clock = hs.get_clock()
         self.federation_domain_whitelist = hs.config.federation_domain_whitelist
 
-    def render_GET(self, request):
-        self.async_render_GET(request)
-        return NOT_DONE_YET
-
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def async_render_GET(self, request):
+    async def _async_render_GET(self, request):
         if len(request.postpath) == 1:
             server, = request.postpath
             query = {server.decode("ascii"): {}}
@@ -114,20 +111,15 @@ class RemoteKey(Resource):
         else:
             raise SynapseError(404, "Not found %r" % request.postpath, Codes.NOT_FOUND)
 
-        yield self.query_keys(request, query, query_remote_on_cache_miss=True)
-
-    def render_POST(self, request):
-        self.async_render_POST(request)
-        return NOT_DONE_YET
+        await self.query_keys(request, query, query_remote_on_cache_miss=True)
 
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def async_render_POST(self, request):
+    async def _async_render_POST(self, request):
         content = parse_json_object_from_request(request)
 
         query = content["server_keys"]
 
-        yield self.query_keys(request, query, query_remote_on_cache_miss=True)
+        await self.query_keys(request, query, query_remote_on_cache_miss=True)
 
     @defer.inlineCallbacks
     def query_keys(self, request, query, query_remote_on_cache_miss=False):
diff --git a/synapse/rest/media/v1/config_resource.py b/synapse/rest/media/v1/config_resource.py
 index fa3d6680fc..9f747de263 100644
--- a/synapse/rest/media/v1/config_resource.py
+++ b/synapse/rest/media/v1/config_resource.py
@@ -14,31 +14,28 @@
 # limitations under the License.
 #
 
-from twisted.internet import defer
-from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
 
-from synapse.http.server import respond_with_json, wrap_json_request_handler
+from synapse.http.server import (
+    DirectServeResource,
+    respond_with_json,
+    wrap_json_request_handler,
+)
 
 
-class MediaConfigResource(Resource):
+class MediaConfigResource(DirectServeResource):
     isLeaf = True
 
     def __init__(self, hs):
-        Resource.__init__(self)
+        super().__init__()
         config = hs.get_config()
         self.clock = hs.get_clock()
         self.auth = hs.get_auth()
         self.limits_dict = {"m.upload.size": config.max_upload_size}
 
-    def render_GET(self, request):
-        self._async_render_GET(request)
-        return NOT_DONE_YET
-
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def _async_render_GET(self, request):
-        yield self.auth.get_user_by_req(request)
+    async def _async_render_GET(self, request):
+        await self.auth.get_user_by_req(request)
         respond_with_json(request, 200, self.limits_dict, send_cors=True)
 
     def render_OPTIONS(self, request):
diff --git a/synapse/rest/media/v1/download_resource.py b/synapse/rest/media/v1/download_resource.py
 index a21a35f843..66a01559e1 100644
--- a/synapse/rest/media/v1/download_resource.py
+++ b/synapse/rest/media/v1/download_resource.py
@@ -14,37 +14,31 @@
 # limitations under the License.
 import logging
 
-from twisted.internet import defer
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
-
 import synapse.http.servlet
-from synapse.http.server import set_cors_headers, wrap_json_request_handler
+from synapse.http.server import (
+    DirectServeResource,
+    set_cors_headers,
+    wrap_json_request_handler,
+)
 
 from ._base import parse_media_id, respond_404
 
 logger = logging.getLogger(__name__)
 
 
-class DownloadResource(Resource):
+class DownloadResource(DirectServeResource):
     isLeaf = True
 
     def __init__(self, hs, media_repo):
-        Resource.__init__(self)
-
+        super().__init__()
         self.media_repo = media_repo
         self.server_name = hs.hostname
 
         # this is expected by @wrap_json_request_handler
         self.clock = hs.get_clock()
 
-    def render_GET(self, request):
-        self._async_render_GET(request)
-        return NOT_DONE_YET
-
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def _async_render_GET(self, request):
+    async def _async_render_GET(self, request):
         set_cors_headers(request)
         request.setHeader(
             b"Content-Security-Policy",
@@ -58,7 +52,7 @@ class DownloadResource(Resource):
         )
         server_name, media_id, name = parse_media_id(request)
         if server_name == self.server_name:
-            yield self.media_repo.get_local_media(request, media_id, name)
+            await self.media_repo.get_local_media(request, media_id, name)
         else:
             allow_remote = synapse.http.servlet.parse_boolean(
                 request, "allow_remote", default=True
@@ -72,4 +66,4 @@ class DownloadResource(Resource):
                 respond_404(request)
                 return
 
-            yield self.media_repo.get_remote_media(request, server_name, media_id, name)
+            await self.media_repo.get_remote_media(request, server_name, media_id, name)
diff --git a/synapse/rest/media/v1/preview_url_resource.py b/synapse/rest/media/v1/preview_url_resource.py
 index de6f292ffb..0337b64dc2 100644
--- a/synapse/rest/media/v1/preview_url_resource.py
+++ b/synapse/rest/media/v1/preview_url_resource.py
@@ -32,12 +32,11 @@ from canonicaljson import json
 
 from twisted.internet import defer
 from twisted.internet.error import DNSLookupError
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
 
 from synapse.api.errors import Codes, SynapseError
 from synapse.http.client import SimpleHttpClient
 from synapse.http.server import (
+    DirectServeResource,
     respond_with_json,
     respond_with_json_bytes,
     wrap_json_request_handler,
@@ -58,11 +57,11 @@ _charset_match = re.compile(br"<\s*meta[^>]*charset\s*=\s*([a-z0-9-]+)", flags=r
 _content_type_match = re.compile(r'.*; *charset="?(.*?)"?(;|$)', flags=re.I)
 
 
-class PreviewUrlResource(Resource):
+class PreviewUrlResource(DirectServeResource):
     isLeaf = True
 
     def __init__(self, hs, media_repo, media_storage):
-        Resource.__init__(self)
+        super().__init__()
 
         self.auth = hs.get_auth()
         self.clock = hs.get_clock()
@@ -98,16 +97,11 @@ class PreviewUrlResource(Resource):
     def render_OPTIONS(self, request):
         return respond_with_json(request, 200, {}, send_cors=True)
 
-    def render_GET(self, request):
-        self._async_render_GET(request)
-        return NOT_DONE_YET
-
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def _async_render_GET(self, request):
+    async def _async_render_GET(self, request):
 
         # XXX: if get_user_by_req fails, what should we do in an async render?
-        requester = yield self.auth.get_user_by_req(request)
+        requester = await self.auth.get_user_by_req(request)
         url = parse_string(request, "url")
         if b"ts" in request.args:
             ts = parse_integer(request, "ts")
@@ -159,7 +153,7 @@ class PreviewUrlResource(Resource):
         else:
             logger.info("Returning cached response")
 
-        og = yield make_deferred_yieldable(observable.observe())
+        og = await make_deferred_yieldable(defer.maybeDeferred(observable.observe))
         respond_with_json_bytes(request, 200, og, send_cors=True)
 
     @defer.inlineCallbacks
diff --git a/synapse/rest/media/v1/thumbnail_resource.py b/synapse/rest/media/v1/thumbnail_resource.py
 index ca84c9f139..08329884ac 100644
--- a/synapse/rest/media/v1/thumbnail_resource.py
+++ b/synapse/rest/media/v1/thumbnail_resource.py
@@ -17,10 +17,12 @@
 import logging
 
 from twisted.internet import defer
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
 
-from synapse.http.server import set_cors_headers, wrap_json_request_handler
+from synapse.http.server import (
+    DirectServeResource,
+    set_cors_headers,
+    wrap_json_request_handler,
+)
 from synapse.http.servlet import parse_integer, parse_string
 
 from ._base import (
@@ -34,11 +36,11 @@ from ._base import (
 logger = logging.getLogger(__name__)
 
 
-class ThumbnailResource(Resource):
+class ThumbnailResource(DirectServeResource):
     isLeaf = True
 
     def __init__(self, hs, media_repo, media_storage):
-        Resource.__init__(self)
+        super().__init__()
 
         self.store = hs.get_datastore()
         self.media_repo = media_repo
@@ -47,13 +49,8 @@ class ThumbnailResource(Resource):
         self.server_name = hs.hostname
         self.clock = hs.get_clock()
 
-    def render_GET(self, request):
-        self._async_render_GET(request)
-        return NOT_DONE_YET
-
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def _async_render_GET(self, request):
+    async def _async_render_GET(self, request):
         set_cors_headers(request)
         server_name, media_id, _ = parse_media_id(request)
         width = parse_integer(request, "width", required=True)
@@ -63,21 +60,21 @@ class ThumbnailResource(Resource):
 
         if server_name == self.server_name:
             if self.dynamic_thumbnails:
-                yield self._select_or_generate_local_thumbnail(
+                await self._select_or_generate_local_thumbnail(
                     request, media_id, width, height, method, m_type
                 )
             else:
-                yield self._respond_local_thumbnail(
+                await self._respond_local_thumbnail(
                     request, media_id, width, height, method, m_type
                 )
             self.media_repo.mark_recently_accessed(None, media_id)
         else:
             if self.dynamic_thumbnails:
-                yield self._select_or_generate_remote_thumbnail(
+                await self._select_or_generate_remote_thumbnail(
                     request, server_name, media_id, width, height, method, m_type
                 )
             else:
-                yield self._respond_remote_thumbnail(
+                await self._respond_remote_thumbnail(
                     request, server_name, media_id, width, height, method, m_type
                 )
             self.media_repo.mark_recently_accessed(server_name, media_id)
diff --git a/synapse/rest/media/v1/upload_resource.py b/synapse/rest/media/v1/upload_resource.py
 index d1d7e959f0..5d76bbdf68 100644
--- a/synapse/rest/media/v1/upload_resource.py
+++ b/synapse/rest/media/v1/upload_resource.py
@@ -15,22 +15,24 @@
 
 import logging
 
-from twisted.internet import defer
-from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
 
 from synapse.api.errors import SynapseError
-from synapse.http.server import respond_with_json, wrap_json_request_handler
+from synapse.http.server import (
+    DirectServeResource,
+    respond_with_json,
+    wrap_json_request_handler,
+)
 from synapse.http.servlet import parse_string
 
 logger = logging.getLogger(__name__)
 
 
-class UploadResource(Resource):
+class UploadResource(DirectServeResource):
     isLeaf = True
 
     def __init__(self, hs, media_repo):
-        Resource.__init__(self)
+        super().__init__()
 
         self.media_repo = media_repo
         self.filepaths = media_repo.filepaths
@@ -41,18 +43,13 @@ class UploadResource(Resource):
         self.max_upload_size = hs.config.max_upload_size
         self.clock = hs.get_clock()
 
-    def render_POST(self, request):
-        self._async_render_POST(request)
-        return NOT_DONE_YET
-
     def render_OPTIONS(self, request):
         respond_with_json(request, 200, {}, send_cors=True)
         return NOT_DONE_YET
 
     @wrap_json_request_handler
-    @defer.inlineCallbacks
-    def _async_render_POST(self, request):
-        requester = yield self.auth.get_user_by_req(request)
+    async def _async_render_POST(self, request):
+        requester = await self.auth.get_user_by_req(request)
         # TODO: The checks here are a bit late. The content will have
         # already been uploaded to a tmp file at this point
         content_length = request.getHeader(b"Content-Length").decode("ascii")
@@ -81,7 +78,7 @@ class UploadResource(Resource):
         #     disposition = headers.getRawHeaders(b"Content-Disposition")[0]
         # TODO(markjh): parse content-dispostion
 
-        content_uri = yield self.media_repo.create_content(
+        content_uri = await self.media_repo.create_content(
             media_type, upload_name, request.content, content_length, requester.user
         )
 
diff --git a/synapse/rest/saml2/response_resource.py b/synapse/rest/saml2/response_resource.py
 index ab14b70675..69ecc5e4b4 100644
--- a/synapse/rest/saml2/response_resource.py
+++ b/synapse/rest/saml2/response_resource.py
@@ -13,59 +13,19 @@
 # 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
 
-import saml2
-from saml2.client import Saml2Client
+from synapse.http.server import DirectServeResource, wrap_html_request_handler
 
-from twisted.web.resource import Resource
-from twisted.web.server import NOT_DONE_YET
 
-from synapse.api.errors import CodeMessageException
-from synapse.http.server import wrap_html_request_handler
-from synapse.http.servlet import parse_string
-from synapse.rest.client.v1.login import SSOAuthHandler
-
-logger = logging.getLogger(__name__)
-
-
-class SAML2ResponseResource(Resource):
+class SAML2ResponseResource(DirectServeResource):
     """A Twisted web resource which handles the SAML response"""
 
     isLeaf = 1
 
     def __init__(self, hs):
-        Resource.__init__(self)
-
-        self._saml_client = Saml2Client(hs.config.saml2_sp_config)
-        self._sso_auth_handler = SSOAuthHandler(hs)
-
-    def render_POST(self, request):
-        self._async_render_POST(request)
-        return NOT_DONE_YET
+        super().__init__()
+        self._saml_handler = hs.get_saml_handler()
 
     @wrap_html_request_handler
-    def _async_render_POST(self, request):
-        resp_bytes = parse_string(request, "SAMLResponse", required=True)
-        relay_state = parse_string(request, "RelayState", required=True)
-
-        try:
-            saml2_auth = self._saml_client.parse_authn_request_response(
-                resp_bytes, saml2.BINDING_HTTP_POST
-            )
-        except Exception as e:
-            logger.warning("Exception parsing SAML2 response", exc_info=1)
-            raise CodeMessageException(400, "Unable to parse SAML2 response: %s" % (e,))
-
-        if saml2_auth.not_signed:
-            raise CodeMessageException(400, "SAML2 response was not signed")
-
-        if "uid" not in saml2_auth.ava:
-            raise CodeMessageException(400, "uid not in SAML2 response")
-
-        username = saml2_auth.ava["uid"][0]
-
-        displayName = saml2_auth.ava.get("displayName", [None])[0]
-        return self._sso_auth_handler.on_successful_auth(
-            username, request, relay_state, user_display_name=displayName
-        )
+    async def _async_render_POST(self, request):
+        return await self._saml_handler.handle_saml_response(request)
diff --git a/synapse/server.py b/synapse/server.py
 index a9592c396c..9e28dba2b1 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -194,6 +194,7 @@ class HomeServer(object):
         "sendmail",
         "registration_handler",
         "account_validity_handler",
+        "saml_handler",
         "event_client_serializer",
     ]
 
@@ -524,6 +525,11 @@ class HomeServer(object):
     def build_account_validity_handler(self):
         return AccountValidityHandler(self)
 
+    def build_saml_handler(self):
+        from synapse.handlers.saml_handler import SamlHandler
+
+        return SamlHandler(self)
+
     def build_event_client_serializer(self):
         return EventClientSerializer(self)
 |