diff --git a/changelog.d/16136.feature b/changelog.d/16136.feature
new file mode 100644
index 0000000000..4ad98a88c3
--- /dev/null
+++ b/changelog.d/16136.feature
@@ -0,0 +1 @@
+Return a `Retry-After` with `M_LIMIT_EXCEEDED` error responses.
diff --git a/synapse/api/errors.py b/synapse/api/errors.py
index 7ffd72c42c..578e798773 100644
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -16,6 +16,7 @@
"""Contains exceptions and error codes."""
import logging
+import math
import typing
from enum import Enum
from http import HTTPStatus
@@ -503,6 +504,8 @@ class InvalidCaptchaError(SynapseError):
class LimitExceededError(SynapseError):
"""A client has sent too many requests and is being throttled."""
+ include_retry_after_header = False
+
def __init__(
self,
code: int = 429,
@@ -510,7 +513,12 @@ class LimitExceededError(SynapseError):
retry_after_ms: Optional[int] = None,
errcode: str = Codes.LIMIT_EXCEEDED,
):
- super().__init__(code, msg, errcode)
+ headers = (
+ {"Retry-After": str(math.ceil(retry_after_ms / 1000))}
+ if self.include_retry_after_header and retry_after_ms is not None
+ else None
+ )
+ super().__init__(code, msg, errcode, headers=headers)
self.retry_after_ms = retry_after_ms
def error_dict(self, config: Optional["HomeServerConfig"]) -> "JsonDict":
diff --git a/synapse/config/experimental.py b/synapse/config/experimental.py
index 84d6dd13af..cabe0d4397 100644
--- a/synapse/config/experimental.py
+++ b/synapse/config/experimental.py
@@ -18,6 +18,7 @@ from typing import TYPE_CHECKING, Any, Optional
import attr
import attr.validators
+from synapse.api.errors import LimitExceededError
from synapse.api.room_versions import KNOWN_ROOM_VERSIONS, RoomVersions
from synapse.config import ConfigError
from synapse.config._base import Config, RootConfig
@@ -406,3 +407,11 @@ class ExperimentalConfig(Config):
self.msc4010_push_rules_account_data = experimental.get(
"msc4010_push_rules_account_data", False
)
+
+ # MSC4041: Use HTTP header Retry-After to enable library-assisted retry handling
+ #
+ # This is a bit hacky, but the most reasonable way to *alway* include the
+ # headers.
+ LimitExceededError.include_retry_after_header = experimental.get(
+ "msc4041_enabled", False
+ )
diff --git a/tests/api/test_errors.py b/tests/api/test_errors.py
new file mode 100644
index 0000000000..319abfe63d
--- /dev/null
+++ b/tests/api/test_errors.py
@@ -0,0 +1,36 @@
+# Copyright 2023 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.
+
+from synapse.api.errors import LimitExceededError
+
+from tests import unittest
+
+
+class ErrorsTestCase(unittest.TestCase):
+ # Create a sub-class to avoid mutating the class-level property.
+ class LimitExceededErrorHeaders(LimitExceededError):
+ include_retry_after_header = True
+
+ def test_limit_exceeded_header(self) -> None:
+ err = ErrorsTestCase.LimitExceededErrorHeaders(retry_after_ms=100)
+ self.assertEqual(err.error_dict(None).get("retry_after_ms"), 100)
+ assert err.headers is not None
+ self.assertEqual(err.headers.get("Retry-After"), "1")
+
+ def test_limit_exceeded_rounding(self) -> None:
+ err = ErrorsTestCase.LimitExceededErrorHeaders(retry_after_ms=3001)
+ self.assertEqual(err.error_dict(None).get("retry_after_ms"), 3001)
+ assert err.headers is not None
+ self.assertEqual(err.headers.get("Retry-After"), "4")
diff --git a/tests/rest/client/test_login.py b/tests/rest/client/test_login.py
index ffbc13bb8d..62c32cae5e 100644
--- a/tests/rest/client/test_login.py
+++ b/tests/rest/client/test_login.py
@@ -169,7 +169,8 @@ class LoginRestServletTestCase(unittest.HomeserverTestCase):
# which sets these values to 10000, but as we're overriding the entire
# rc_login dict here, we need to set this manually as well
"account": {"per_second": 10000, "burst_count": 10000},
- }
+ },
+ "experimental_features": {"msc4041_enabled": True},
}
)
def test_POST_ratelimiting_per_address(self) -> None:
@@ -189,12 +190,15 @@ class LoginRestServletTestCase(unittest.HomeserverTestCase):
if i == 5:
self.assertEqual(channel.code, 429, msg=channel.result)
retry_after_ms = int(channel.json_body["retry_after_ms"])
+ retry_header = channel.headers.getRawHeaders("Retry-After")
else:
self.assertEqual(channel.code, 200, msg=channel.result)
# Since we're ratelimiting at 1 request/min, retry_after_ms should be lower
# than 1min.
- self.assertTrue(retry_after_ms < 6000)
+ self.assertLess(retry_after_ms, 6000)
+ assert retry_header
+ self.assertLessEqual(int(retry_header[0]), 6)
self.reactor.advance(retry_after_ms / 1000.0 + 1.0)
@@ -217,7 +221,8 @@ class LoginRestServletTestCase(unittest.HomeserverTestCase):
# which sets these values to 10000, but as we're overriding the entire
# rc_login dict here, we need to set this manually as well
"address": {"per_second": 10000, "burst_count": 10000},
- }
+ },
+ "experimental_features": {"msc4041_enabled": True},
}
)
def test_POST_ratelimiting_per_account(self) -> None:
@@ -234,12 +239,15 @@ class LoginRestServletTestCase(unittest.HomeserverTestCase):
if i == 5:
self.assertEqual(channel.code, 429, msg=channel.result)
retry_after_ms = int(channel.json_body["retry_after_ms"])
+ retry_header = channel.headers.getRawHeaders("Retry-After")
else:
self.assertEqual(channel.code, 200, msg=channel.result)
# Since we're ratelimiting at 1 request/min, retry_after_ms should be lower
# than 1min.
- self.assertTrue(retry_after_ms < 6000)
+ self.assertLess(retry_after_ms, 6000)
+ assert retry_header
+ self.assertLessEqual(int(retry_header[0]), 6)
self.reactor.advance(retry_after_ms / 1000.0)
@@ -262,7 +270,8 @@ class LoginRestServletTestCase(unittest.HomeserverTestCase):
# rc_login dict here, we need to set this manually as well
"address": {"per_second": 10000, "burst_count": 10000},
"failed_attempts": {"per_second": 0.17, "burst_count": 5},
- }
+ },
+ "experimental_features": {"msc4041_enabled": True},
}
)
def test_POST_ratelimiting_per_account_failed_attempts(self) -> None:
@@ -279,12 +288,15 @@ class LoginRestServletTestCase(unittest.HomeserverTestCase):
if i == 5:
self.assertEqual(channel.code, 429, msg=channel.result)
retry_after_ms = int(channel.json_body["retry_after_ms"])
+ retry_header = channel.headers.getRawHeaders("Retry-After")
else:
self.assertEqual(channel.code, 403, msg=channel.result)
# Since we're ratelimiting at 1 request/min, retry_after_ms should be lower
# than 1min.
- self.assertTrue(retry_after_ms < 6000)
+ self.assertLess(retry_after_ms, 6000)
+ assert retry_header
+ self.assertLessEqual(int(retry_header[0]), 6)
self.reactor.advance(retry_after_ms / 1000.0 + 1.0)
|
