1 files changed, 104 insertions, 0 deletions
diff --git a/synapse/api/auth_blocking.py b/synapse/api/auth_blocking.py
new file mode 100644
index 0000000000..5c499b6b4e
--- /dev/null
+++ b/synapse/api/auth_blocking.py
@@ -0,0 +1,104 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 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 twisted.internet import defer
+
+from synapse.api.constants import LimitBlockingTypes, UserTypes
+from synapse.api.errors import Codes, ResourceLimitError
+from synapse.config.server import is_threepid_reserved
+
+logger = logging.getLogger(__name__)
+
+
+class AuthBlocking(object):
+    def __init__(self, hs):
+        self.store = hs.get_datastore()
+
+        self._server_notices_mxid = hs.config.server_notices_mxid
+        self._hs_disabled = hs.config.hs_disabled
+        self._hs_disabled_message = hs.config.hs_disabled_message
+        self._admin_contact = hs.config.admin_contact
+        self._max_mau_value = hs.config.max_mau_value
+        self._limit_usage_by_mau = hs.config.limit_usage_by_mau
+        self._mau_limits_reserved_threepids = hs.config.mau_limits_reserved_threepids
+
+    @defer.inlineCallbacks
+    def check_auth_blocking(self, user_id=None, threepid=None, user_type=None):
+        """Checks if the user should be rejected for some external reason,
+        such as monthly active user limiting or global disable flag
+
+        Args:
+            user_id(str|None): If present, checks for presence against existing
+                MAU cohort
+
+            threepid(dict|None): If present, checks for presence against configured
+                reserved threepid. Used in cases where the user is trying register
+                with a MAU blocked server, normally they would be rejected but their
+                threepid is on the reserved list. user_id and
+                threepid should never be set at the same time.
+
+            user_type(str|None): If present, is used to decide whether to check against
+                certain blocking reasons like MAU.
+        """
+
+        # Never fail an auth check for the server notices users or support user
+        # This can be a problem where event creation is prohibited due to blocking
+        if user_id is not None:
+            if user_id == self._server_notices_mxid:
+                return
+            if (yield self.store.is_support_user(user_id)):
+                return
+
+        if self._hs_disabled:
+            raise ResourceLimitError(
+                403,
+                self._hs_disabled_message,
+                errcode=Codes.RESOURCE_LIMIT_EXCEEDED,
+                admin_contact=self._admin_contact,
+                limit_type=LimitBlockingTypes.HS_DISABLED,
+            )
+        if self._limit_usage_by_mau is True:
+            assert not (user_id and threepid)
+
+            # If the user is already part of the MAU cohort or a trial user
+            if user_id:
+                timestamp = yield self.store.user_last_seen_monthly_active(user_id)
+                if timestamp:
+                    return
+
+                is_trial = yield self.store.is_trial_user(user_id)
+                if is_trial:
+                    return
+            elif threepid:
+                # If the user does not exist yet, but is signing up with a
+                # reserved threepid then pass auth check
+                if is_threepid_reserved(self._mau_limits_reserved_threepids, threepid):
+                    return
+            elif user_type == UserTypes.SUPPORT:
+                # If the user does not exist yet and is of type "support",
+                # allow registration. Support users are excluded from MAU checks.
+                return
+            # Else if there is no room in the MAU bucket, bail
+            current_mau = yield self.store.get_monthly_active_count()
+            if current_mau >= self._max_mau_value:
+                raise ResourceLimitError(
+                    403,
+                    "Monthly Active User Limit Exceeded",
+                    admin_contact=self._admin_contact,
+                    errcode=Codes.RESOURCE_LIMIT_EXCEEDED,
+                    limit_type=LimitBlockingTypes.MONTHLY_ACTIVE_USER,
+                )