Move Account Validity callbacks to a dedicated file (#15237)

3 files changed, 124 insertions, 9 deletions

diff --git a/synapse/module_api/__init__.py b/synapse/module_api/__init__.py
index 424239e3df..595c23e78d 100644
--- a/synapse/module_api/__init__.py
+++ b/synapse/module_api/__init__.py
@@ -73,13 +73,6 @@ from synapse.events.third_party_rules import (
     ON_USER_DEACTIVATION_STATUS_CHANGED_CALLBACK,
 )
 from synapse.handlers.account_data import ON_ACCOUNT_DATA_UPDATED_CALLBACK
-from synapse.handlers.account_validity import (
-    IS_USER_EXPIRED_CALLBACK,
-    ON_LEGACY_ADMIN_REQUEST,
-    ON_LEGACY_RENEW_CALLBACK,
-    ON_LEGACY_SEND_MAIL_CALLBACK,
-    ON_USER_REGISTRATION_CALLBACK,
-)
 from synapse.handlers.auth import (
     CHECK_3PID_AUTH_CALLBACK,
     CHECK_AUTH_CALLBACK,
@@ -105,6 +98,13 @@ from synapse.logging.context import (
     run_in_background,
 )
 from synapse.metrics.background_process_metrics import run_as_background_process
+from synapse.module_api.callbacks.account_validity_callbacks import (
+    IS_USER_EXPIRED_CALLBACK,
+    ON_LEGACY_ADMIN_REQUEST,
+    ON_LEGACY_RENEW_CALLBACK,
+    ON_LEGACY_SEND_MAIL_CALLBACK,
+    ON_USER_REGISTRATION_CALLBACK,
+)
 from synapse.rest.client.login import LoginResponse
 from synapse.storage import DataStore
 from synapse.storage.background_updates import (
@@ -250,6 +250,7 @@ class ModuleApi:
         self._push_rules_handler = hs.get_push_rules_handler()
         self._device_handler = hs.get_device_handler()
         self.custom_template_dir = hs.config.server.custom_template_directory
+        self._callbacks = hs.get_module_api_callbacks()
 
         try:
             app_name = self._hs.config.email.email_app_name
@@ -271,7 +272,6 @@ class ModuleApi:
         self._account_data_manager = AccountDataManager(hs)
 
         self._spam_checker = hs.get_spam_checker()
-        self._account_validity_handler = hs.get_account_validity_handler()
         self._third_party_event_rules = hs.get_third_party_event_rules()
         self._password_auth_provider = hs.get_password_auth_provider()
         self._presence_router = hs.get_presence_router()
@@ -332,7 +332,7 @@ class ModuleApi:
 
         Added in Synapse v1.39.0.
         """
-        return self._account_validity_handler.register_account_validity_callbacks(
+        return self._callbacks.account_validity.register_callbacks(
             is_user_expired=is_user_expired,
             on_user_registration=on_user_registration,
             on_legacy_send_mail=on_legacy_send_mail,
diff --git a/synapse/module_api/callbacks/__init__.py b/synapse/module_api/callbacks/__init__.py
new file mode 100644
index 0000000000..3d977bf655
--- /dev/null
+++ b/synapse/module_api/callbacks/__init__.py
@@ -0,0 +1,22 @@
+# 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.module_api.callbacks.account_validity_callbacks import (
+    AccountValidityModuleApiCallbacks,
+)
+
+
+class ModuleApiCallbacks:
+    def __init__(self) -> None:
+        self.account_validity = AccountValidityModuleApiCallbacks()
diff --git a/synapse/module_api/callbacks/account_validity_callbacks.py b/synapse/module_api/callbacks/account_validity_callbacks.py
new file mode 100644
index 0000000000..531d0c9ddc
--- /dev/null
+++ b/synapse/module_api/callbacks/account_validity_callbacks.py
@@ -0,0 +1,93 @@
+# 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.
+
+import logging
+from typing import Awaitable, Callable, List, Optional, Tuple
+
+from twisted.web.http import Request
+
+logger = logging.getLogger(__name__)
+
+# Types for callbacks to be registered via the module api
+IS_USER_EXPIRED_CALLBACK = Callable[[str], Awaitable[Optional[bool]]]
+ON_USER_REGISTRATION_CALLBACK = Callable[[str], Awaitable]
+# Temporary hooks to allow for a transition from `/_matrix/client` endpoints
+# to `/_synapse/client/account_validity`. See `register_callbacks` below.
+ON_LEGACY_SEND_MAIL_CALLBACK = Callable[[str], Awaitable]
+ON_LEGACY_RENEW_CALLBACK = Callable[[str], Awaitable[Tuple[bool, bool, int]]]
+ON_LEGACY_ADMIN_REQUEST = Callable[[Request], Awaitable]
+
+
+class AccountValidityModuleApiCallbacks:
+    def __init__(self) -> None:
+        self.is_user_expired_callbacks: List[IS_USER_EXPIRED_CALLBACK] = []
+        self.on_user_registration_callbacks: List[ON_USER_REGISTRATION_CALLBACK] = []
+        self.on_legacy_send_mail_callback: Optional[ON_LEGACY_SEND_MAIL_CALLBACK] = None
+        self.on_legacy_renew_callback: Optional[ON_LEGACY_RENEW_CALLBACK] = None
+
+        # The legacy admin requests callback isn't a protected attribute because we need
+        # to access it from the admin servlet, which is outside of this handler.
+        self.on_legacy_admin_request_callback: Optional[ON_LEGACY_ADMIN_REQUEST] = None
+
+    def register_callbacks(
+        self,
+        is_user_expired: Optional[IS_USER_EXPIRED_CALLBACK] = None,
+        on_user_registration: Optional[ON_USER_REGISTRATION_CALLBACK] = None,
+        on_legacy_send_mail: Optional[ON_LEGACY_SEND_MAIL_CALLBACK] = None,
+        on_legacy_renew: Optional[ON_LEGACY_RENEW_CALLBACK] = None,
+        on_legacy_admin_request: Optional[ON_LEGACY_ADMIN_REQUEST] = None,
+    ) -> None:
+        """Register callbacks from module for each hook."""
+        if is_user_expired is not None:
+            self.is_user_expired_callbacks.append(is_user_expired)
+
+        if on_user_registration is not None:
+            self.on_user_registration_callbacks.append(on_user_registration)
+
+        # The builtin account validity feature exposes 3 endpoints (send_mail, renew, and
+        # an admin one). As part of moving the feature into a module, we need to change
+        # the path from /_matrix/client/unstable/account_validity/... to
+        # /_synapse/client/account_validity, because:
+        #
+        #   * the feature isn't part of the Matrix spec thus shouldn't live under /_matrix
+        #   * the way we register servlets means that modules can't register resources
+        #     under /_matrix/client
+        #
+        # We need to allow for a transition period between the old and new endpoints
+        # in order to allow for clients to update (and for emails to be processed).
+        #
+        # Once the email-account-validity module is loaded, it will take control of account
+        # validity by moving the rows from our `account_validity` table into its own table.
+        #
+        # Therefore, we need to allow modules (in practice just the one implementing the
+        # email-based account validity) to temporarily hook into the legacy endpoints so we
+        # can route the traffic coming into the old endpoints into the module, which is
+        # why we have the following three temporary hooks.
+        if on_legacy_send_mail is not None:
+            if self.on_legacy_send_mail_callback is not None:
+                raise RuntimeError("Tried to register on_legacy_send_mail twice")
+
+            self.on_legacy_send_mail_callback = on_legacy_send_mail
+
+        if on_legacy_renew is not None:
+            if self.on_legacy_renew_callback is not None:
+                raise RuntimeError("Tried to register on_legacy_renew twice")
+
+            self.on_legacy_renew_callback = on_legacy_renew
+
+        if on_legacy_admin_request is not None:
+            if self.on_legacy_admin_request_callback is not None:
+                raise RuntimeError("Tried to register on_legacy_admin_request twice")
+
+            self.on_legacy_admin_request_callback = on_legacy_admin_request