2 files changed, 48 insertions, 8 deletions
diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index 9c62ec4374..022211e34e 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -25,7 +25,7 @@ from twisted.internet import defer
 import synapse.types
 from synapse import event_auth
 from synapse.api.constants import EventTypes, JoinRules, Membership
-from synapse.api.errors import AuthError, Codes
+from synapse.api.errors import AuthError, Codes, ResourceLimitError
 from synapse.types import UserID
 from synapse.util.caches import CACHE_SIZE_FACTOR, register_cache
 from synapse.util.caches.lrucache import LruCache
@@ -775,17 +775,34 @@ 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
+            raise ResourceLimitError(
+                403, self.hs.config.hs_disabled_message,
+                errcode=Codes.RESOURCE_LIMIT_EXCEED,
+                admin_uri=self.hs.config.admin_uri,
+                limit_type=self.hs.config.hs_disabled_limit_type
             )
         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(
-                    403, "MAU Limit Exceeded", errcode=Codes.MAU_LIMIT_EXCEEDED
+                raise ResourceLimitError(
+                    403, "Monthly Active User Limit Exceeded",
+
+                    admin_uri=self.hs.config.admin_uri,
+                    errcode=Codes.RESOURCE_LIMIT_EXCEED,
+                    limit_type="monthly_active_user"
                 )
diff --git a/synapse/api/errors.py b/synapse/api/errors.py
index dc3bed5fcb..e26001ab12 100644
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -56,8 +56,7 @@ class Codes(object):
     SERVER_NOT_TRUSTED = "M_SERVER_NOT_TRUSTED"
     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"
+    RESOURCE_LIMIT_EXCEED = "M_RESOURCE_LIMIT_EXCEED"
     UNSUPPORTED_ROOM_VERSION = "M_UNSUPPORTED_ROOM_VERSION"
     INCOMPATIBLE_ROOM_VERSION = "M_INCOMPATIBLE_ROOM_VERSION"
 
@@ -232,6 +231,30 @@ class AuthError(SynapseError):
         super(AuthError, self).__init__(*args, **kwargs)
 
 
+class ResourceLimitError(SynapseError):
+    """
+    Any error raised when there is a problem with resource usage.
+    For instance, the monthly active user limit for the server has been exceeded
+    """
+    def __init__(
+        self, code, msg,
+        errcode=Codes.RESOURCE_LIMIT_EXCEED,
+        admin_uri=None,
+        limit_type=None,
+    ):
+        self.admin_uri = admin_uri
+        self.limit_type = limit_type
+        super(ResourceLimitError, self).__init__(code, msg, errcode=errcode)
+
+    def error_dict(self):
+        return cs_error(
+            self.msg,
+            self.errcode,
+            admin_uri=self.admin_uri,
+            limit_type=self.limit_type
+        )
+
+
 class EventSizeError(SynapseError):
     """An error raised when an event is too big."""