Merge pull request #3707 from matrix-org/neilj/limit_exceeded_error

add new error type ResourceLimit

3 files changed, 55 insertions, 6 deletions

diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index ab1e3a4e35..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
@@ -784,10 +784,11 @@ class Auth(object):
             MAU cohort
         """
         if self.hs.config.hs_disabled:
-            raise AuthError(
+            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
@@ -798,8 +799,10 @@ class Auth(object):
             # 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(
+                raise ResourceLimitError(
                     403, "Monthly Active User Limit Exceeded",
+
                     admin_uri=self.hs.config.admin_uri,
-                    errcode=Codes.RESOURCE_LIMIT_EXCEED
+                    errcode=Codes.RESOURCE_LIMIT_EXCEED,
+                    limit_type="monthly_active_user"
                 )
diff --git a/synapse/api/errors.py b/synapse/api/errors.py
index 08f0cb5554..e26001ab12 100644
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -224,15 +224,34 @@ class NotFoundError(SynapseError):
 
 class AuthError(SynapseError):
     """An error raised when there was a problem authorising an event."""
-    def __init__(self, code, msg, errcode=Codes.FORBIDDEN, admin_uri=None):
+
+    def __init__(self, *args, **kwargs):
+        if "errcode" not in kwargs:
+            kwargs["errcode"] = Codes.FORBIDDEN
+        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
-        super(AuthError, self).__init__(code, msg, errcode=errcode)
+        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
         )
 
 
diff --git a/synapse/config/server.py b/synapse/config/server.py
index 2190f3210a..a41c48e69c 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -81,6 +81,7 @@ class ServerConfig(Config):
         # Options to disable HS
         self.hs_disabled = config.get("hs_disabled", False)
         self.hs_disabled_message = config.get("hs_disabled_message", "")
+        self.hs_disabled_limit_type = config.get("hs_disabled_limit_type", "")
 
         # Admin uri to direct users at should their instance become blocked
         # due to resource constraints
@@ -340,6 +341,32 @@ class ServerConfig(Config):
           # - port: 9000
           #   bind_addresses: ['::1', '127.0.0.1']
           #   type: manhole
+
+
+          # Homeserver blocking
+          #
+          # How to reach the server admin, used in ResourceLimitError
+          # admin_uri: 'mailto:admin@server.com'
+          #
+          # Global block config
+          #
+          # hs_disabled: False
+          # hs_disabled_message: 'Human readable reason for why the HS is blocked'
+          # hs_disabled_limit_type: 'error code(str), to help clients decode reason'
+          #
+          # Monthly Active User Blocking
+          #
+          # Enables monthly active user checking
+          # limit_usage_by_mau: False
+          # max_mau_value: 50
+          #
+          # Sometimes the server admin will want to ensure certain accounts are
+          # never blocked by mau checking. These accounts are specified here.
+          #
+          # mau_limit_reserved_threepids:
+          # - medium: 'email'
+          #   address: 'reserved_user@example.com'
+
         """ % locals()
 
     def read_arguments(self, args):