2 files changed, 16 insertions, 1 deletions
diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index 91b23ff1d7..18c73f0549 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -775,11 +775,25 @@ class Auth(object):
             )
 
     @defer.inlineCallbacks
-    def check_auth_blocking(self):
+    def check_auth_blocking(self, user_id=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
         """
+        if self.hs.config.hs_disabled:
+            raise AuthError(
+                403, self.hs.config.hs_disabled_message, errcode=Codes.HS_DISABLED
+            )
         if self.hs.config.limit_usage_by_mau is True:
+            # If the user is already part of the MAU cohort
+            if user_id:
+                timestamp = yield self.store.user_last_seen_monthly_active(user_id)
+                if timestamp:
+                    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.hs.config.max_mau_value:
                 raise AuthError(
diff --git a/synapse/api/errors.py b/synapse/api/errors.py
index 70400347bc..dc3bed5fcb 100644
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -57,6 +57,7 @@ class Codes(object):
     CONSENT_NOT_GIVEN = "M_CONSENT_NOT_GIVEN"
     CANNOT_LEAVE_SERVER_NOTICE_ROOM = "M_CANNOT_LEAVE_SERVER_NOTICE_ROOM"
     MAU_LIMIT_EXCEEDED = "M_MAU_LIMIT_EXCEEDED"
+    HS_DISABLED = "M_HS_DISABLED"
     UNSUPPORTED_ROOM_VERSION = "M_UNSUPPORTED_ROOM_VERSION"
     INCOMPATIBLE_ROOM_VERSION = "M_INCOMPATIBLE_ROOM_VERSION"