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

add new error type ResourceLimit

9 files changed, 75 insertions, 24 deletions

diff --git a/changelog.d/3707.misc b/changelog.d/3707.misc
new file mode 100644
index 0000000000..8123ca6543
--- /dev/null
+++ b/changelog.d/3707.misc
@@ -0,0 +1 @@
+add new error type ResourceLimit
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):
diff --git a/tests/api/test_auth.py b/tests/api/test_auth.py
index 32a2b5fc3d..022d81ce3e 100644
--- a/tests/api/test_auth.py
+++ b/tests/api/test_auth.py
@@ -21,7 +21,7 @@ from twisted.internet import defer
 
 import synapse.handlers.auth
 from synapse.api.auth import Auth
-from synapse.api.errors import AuthError, Codes
+from synapse.api.errors import AuthError, Codes, ResourceLimitError
 from synapse.types import UserID
 
 from tests import unittest
@@ -455,7 +455,7 @@ class AuthTestCase(unittest.TestCase):
             return_value=defer.succeed(lots_of_users)
         )
 
-        with self.assertRaises(AuthError) as e:
+        with self.assertRaises(ResourceLimitError) as e:
             yield self.auth.check_auth_blocking()
         self.assertEquals(e.exception.admin_uri, self.hs.config.admin_uri)
         self.assertEquals(e.exception.errcode, Codes.RESOURCE_LIMIT_EXCEED)
@@ -471,7 +471,7 @@ class AuthTestCase(unittest.TestCase):
     def test_hs_disabled(self):
         self.hs.config.hs_disabled = True
         self.hs.config.hs_disabled_message = "Reason for being disabled"
-        with self.assertRaises(AuthError) as e:
+        with self.assertRaises(ResourceLimitError) as e:
             yield self.auth.check_auth_blocking()
         self.assertEquals(e.exception.admin_uri, self.hs.config.admin_uri)
         self.assertEquals(e.exception.errcode, Codes.RESOURCE_LIMIT_EXCEED)
diff --git a/tests/handlers/test_auth.py b/tests/handlers/test_auth.py
index 3046bd6093..1e39fe0ec2 100644
--- a/tests/handlers/test_auth.py
+++ b/tests/handlers/test_auth.py
@@ -20,7 +20,7 @@ from twisted.internet import defer
 
 import synapse
 import synapse.api.errors
-from synapse.api.errors import AuthError
+from synapse.api.errors import ResourceLimitError
 from synapse.handlers.auth import AuthHandler
 
 from tests import unittest
@@ -130,13 +130,13 @@ class AuthTestCase(unittest.TestCase):
             return_value=defer.succeed(self.large_number_of_users)
         )
 
-        with self.assertRaises(AuthError):
+        with self.assertRaises(ResourceLimitError):
             yield self.auth_handler.get_access_token_for_user_id('user_a')
 
         self.hs.get_datastore().get_monthly_active_count = Mock(
             return_value=defer.succeed(self.large_number_of_users)
         )
-        with self.assertRaises(AuthError):
+        with self.assertRaises(ResourceLimitError):
             yield self.auth_handler.validate_short_term_login_token_and_get_user_id(
                 self._get_macaroon().serialize()
             )
@@ -149,13 +149,13 @@ class AuthTestCase(unittest.TestCase):
         self.hs.get_datastore().get_monthly_active_count = Mock(
             return_value=defer.succeed(self.hs.config.max_mau_value)
         )
-        with self.assertRaises(AuthError):
+        with self.assertRaises(ResourceLimitError):
             yield self.auth_handler.get_access_token_for_user_id('user_a')
 
         self.hs.get_datastore().get_monthly_active_count = Mock(
             return_value=defer.succeed(self.hs.config.max_mau_value)
         )
-        with self.assertRaises(AuthError):
+        with self.assertRaises(ResourceLimitError):
             yield self.auth_handler.validate_short_term_login_token_and_get_user_id(
                 self._get_macaroon().serialize()
             )
diff --git a/tests/handlers/test_register.py b/tests/handlers/test_register.py
index 7154816a34..7b4ade3dfb 100644
--- a/tests/handlers/test_register.py
+++ b/tests/handlers/test_register.py
@@ -17,7 +17,7 @@ from mock import Mock
 
 from twisted.internet import defer
 
-from synapse.api.errors import AuthError
+from synapse.api.errors import ResourceLimitError
 from synapse.handlers.register import RegistrationHandler
 from synapse.types import UserID, create_requester
 
@@ -109,13 +109,13 @@ class RegistrationTestCase(unittest.TestCase):
         self.store.get_monthly_active_count = Mock(
             return_value=defer.succeed(self.lots_of_users)
         )
-        with self.assertRaises(AuthError):
+        with self.assertRaises(ResourceLimitError):
             yield self.handler.get_or_create_user("requester", 'b', "display_name")
 
         self.store.get_monthly_active_count = Mock(
             return_value=defer.succeed(self.hs.config.max_mau_value)
         )
-        with self.assertRaises(AuthError):
+        with self.assertRaises(ResourceLimitError):
             yield self.handler.get_or_create_user("requester", 'b', "display_name")
 
     @defer.inlineCallbacks
@@ -124,13 +124,13 @@ class RegistrationTestCase(unittest.TestCase):
         self.store.get_monthly_active_count = Mock(
             return_value=defer.succeed(self.lots_of_users)
         )
-        with self.assertRaises(AuthError):
+        with self.assertRaises(ResourceLimitError):
             yield self.handler.register(localpart="local_part")
 
         self.store.get_monthly_active_count = Mock(
             return_value=defer.succeed(self.hs.config.max_mau_value)
         )
-        with self.assertRaises(AuthError):
+        with self.assertRaises(ResourceLimitError):
             yield self.handler.register(localpart="local_part")
 
     @defer.inlineCallbacks
@@ -139,11 +139,11 @@ class RegistrationTestCase(unittest.TestCase):
         self.store.get_monthly_active_count = Mock(
             return_value=defer.succeed(self.lots_of_users)
         )
-        with self.assertRaises(AuthError):
+        with self.assertRaises(ResourceLimitError):
             yield self.handler.register_saml2(localpart="local_part")
 
         self.store.get_monthly_active_count = Mock(
             return_value=defer.succeed(self.hs.config.max_mau_value)
         )
-        with self.assertRaises(AuthError):
+        with self.assertRaises(ResourceLimitError):
             yield self.handler.register_saml2(localpart="local_part")
diff --git a/tests/handlers/test_sync.py b/tests/handlers/test_sync.py
index 33d861bd64..a01ab471f5 100644
--- a/tests/handlers/test_sync.py
+++ b/tests/handlers/test_sync.py
@@ -14,7 +14,7 @@
 # limitations under the License.
 from twisted.internet import defer
 
-from synapse.api.errors import AuthError, Codes
+from synapse.api.errors import Codes, ResourceLimitError
 from synapse.api.filtering import DEFAULT_FILTER_COLLECTION
 from synapse.handlers.sync import SyncConfig, SyncHandler
 from synapse.types import UserID
@@ -49,7 +49,7 @@ class SyncTestCase(tests.unittest.TestCase):
 
         # Test that global lock works
         self.hs.config.hs_disabled = True
-        with self.assertRaises(AuthError) as e:
+        with self.assertRaises(ResourceLimitError) as e:
             yield self.sync_handler.wait_for_sync_for_user(sync_config)
         self.assertEquals(e.exception.errcode, Codes.RESOURCE_LIMIT_EXCEED)
 
@@ -57,7 +57,7 @@ class SyncTestCase(tests.unittest.TestCase):
 
         sync_config = self._generate_sync_config(user_id2)
 
-        with self.assertRaises(AuthError) as e:
+        with self.assertRaises(ResourceLimitError) as e:
             yield self.sync_handler.wait_for_sync_for_user(sync_config)
         self.assertEquals(e.exception.errcode, Codes.RESOURCE_LIMIT_EXCEED)
 
diff --git a/tests/utils.py b/tests/utils.py
index 52326d4f67..6f8b1de3e7 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -137,6 +137,7 @@ def setup_test_homeserver(
         config.limit_usage_by_mau = False
         config.hs_disabled = False
         config.hs_disabled_message = ""
+        config.hs_disabled_limit_type = ""
         config.max_mau_value = 50
         config.mau_limits_reserved_threepids = []
         config.admin_uri = None