Don't remember `enabled` of deleted push rules and properly return 404 for missing push rules in `.../actions` and `.../enabled` (#7796)

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

Co-authored-by: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

3 files changed, 161 insertions, 13 deletions

diff --git a/synapse/rest/client/v1/push_rule.py b/synapse/rest/client/v1/push_rule.py
index e781a3bcf4..ddf8ed5e9c 100644
--- a/synapse/rest/client/v1/push_rule.py
+++ b/synapse/rest/client/v1/push_rule.py
@@ -163,6 +163,18 @@ class PushRuleRestServlet(RestServlet):
         self.notifier.on_new_event("push_rules_key", stream_id, users=[user_id])
 
     async def set_rule_attr(self, user_id, spec, val):
+        if spec["attr"] not in ("enabled", "actions"):
+            # for the sake of potential future expansion, shouldn't report
+            # 404 in the case of an unknown request so check it corresponds to
+            # a known attribute first.
+            raise UnrecognizedRequestError()
+
+        namespaced_rule_id = _namespaced_rule_id_from_spec(spec)
+        rule_id = spec["rule_id"]
+        is_default_rule = rule_id.startswith(".")
+        if is_default_rule:
+            if namespaced_rule_id not in BASE_RULE_IDS:
+                raise NotFoundError("Unknown rule %s" % (namespaced_rule_id,))
         if spec["attr"] == "enabled":
             if isinstance(val, dict) and "enabled" in val:
                 val = val["enabled"]
@@ -171,9 +183,8 @@ class PushRuleRestServlet(RestServlet):
                 # This should *actually* take a dict, but many clients pass
                 # bools directly, so let's not break them.
                 raise SynapseError(400, "Value for 'enabled' must be boolean")
-            namespaced_rule_id = _namespaced_rule_id_from_spec(spec)
             return await self.store.set_push_rule_enabled(
-                user_id, namespaced_rule_id, val
+                user_id, namespaced_rule_id, val, is_default_rule
             )
         elif spec["attr"] == "actions":
             actions = val.get("actions")
diff --git a/synapse/storage/databases/main/push_rule.py b/synapse/storage/databases/main/push_rule.py
index 0de802a86b..9790a31998 100644
--- a/synapse/storage/databases/main/push_rule.py
+++ b/synapse/storage/databases/main/push_rule.py
@@ -13,11 +13,11 @@
 # 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 abc
 import logging
 from typing import List, Tuple, Union
 
+from synapse.api.errors import NotFoundError, StoreError
 from synapse.push.baserules import list_with_base_rules
 from synapse.replication.slave.storage._slaved_id_tracker import SlavedIdTracker
 from synapse.storage._base import SQLBaseStore, db_to_json
@@ -27,6 +27,7 @@ from synapse.storage.databases.main.events_worker import EventsWorkerStore
 from synapse.storage.databases.main.pusher import PusherWorkerStore
 from synapse.storage.databases.main.receipts import ReceiptsWorkerStore
 from synapse.storage.databases.main.roommember import RoomMemberWorkerStore
+from synapse.storage.engines import PostgresEngine, Sqlite3Engine
 from synapse.storage.push_rule import InconsistentRuleException, RuleNotFoundException
 from synapse.storage.util.id_generators import StreamIdGenerator
 from synapse.util import json_encoder
@@ -540,6 +541,25 @@ class PushRuleStore(PushRulesWorkerStore):
                 },
             )
 
+        # ensure we have a push_rules_enable row
+        # enabledness defaults to true
+        if isinstance(self.database_engine, PostgresEngine):
+            sql = """
+                INSERT INTO push_rules_enable (id, user_name, rule_id, enabled)
+                VALUES (?, ?, ?, ?)
+                ON CONFLICT DO NOTHING
+            """
+        elif isinstance(self.database_engine, Sqlite3Engine):
+            sql = """
+                INSERT OR IGNORE INTO push_rules_enable (id, user_name, rule_id, enabled)
+                VALUES (?, ?, ?, ?)
+            """
+        else:
+            raise RuntimeError("Unknown database engine")
+
+        new_enable_id = self._push_rules_enable_id_gen.get_next()
+        txn.execute(sql, (new_enable_id, user_id, rule_id, 1))
+
     async def delete_push_rule(self, user_id: str, rule_id: str) -> None:
         """
         Delete a push rule. Args specify the row to be deleted and can be
@@ -552,6 +572,12 @@ class PushRuleStore(PushRulesWorkerStore):
         """
 
         def delete_push_rule_txn(txn, stream_id, event_stream_ordering):
+            # we don't use simple_delete_one_txn because that would fail if the
+            # user did not have a push_rule_enable row.
+            self.db_pool.simple_delete_txn(
+                txn, "push_rules_enable", {"user_name": user_id, "rule_id": rule_id}
+            )
+
             self.db_pool.simple_delete_one_txn(
                 txn, "push_rules", {"user_name": user_id, "rule_id": rule_id}
             )
@@ -570,10 +596,29 @@ class PushRuleStore(PushRulesWorkerStore):
                 event_stream_ordering,
             )
 
-    async def set_push_rule_enabled(self, user_id, rule_id, enabled) -> None:
+    async def set_push_rule_enabled(
+        self, user_id: str, rule_id: str, enabled: bool, is_default_rule: bool
+    ) -> None:
+        """
+        Sets the `enabled` state of a push rule.
+
+        Args:
+            user_id: the user ID of the user who wishes to enable/disable the rule
+                e.g. '@tina:example.org'
+            rule_id: the full rule ID of the rule to be enabled/disabled
+                e.g. 'global/override/.m.rule.roomnotif'
+                  or 'global/override/myCustomRule'
+            enabled: True if the rule is to be enabled, False if it is to be
+                disabled
+            is_default_rule: True if and only if this is a server-default rule.
+                This skips the check for existence (as only user-created rules
+                are always stored in the database `push_rules` table).
+
+        Raises:
+            NotFoundError if the rule does not exist.
+        """
         with await self._push_rules_stream_id_gen.get_next() as stream_id:
             event_stream_ordering = self._stream_id_gen.get_current_token()
-
             await self.db_pool.runInteraction(
                 "_set_push_rule_enabled_txn",
                 self._set_push_rule_enabled_txn,
@@ -582,12 +627,47 @@ class PushRuleStore(PushRulesWorkerStore):
                 user_id,
                 rule_id,
                 enabled,
+                is_default_rule,
             )
 
     def _set_push_rule_enabled_txn(
-        self, txn, stream_id, event_stream_ordering, user_id, rule_id, enabled
+        self,
+        txn,
+        stream_id,
+        event_stream_ordering,
+        user_id,
+        rule_id,
+        enabled,
+        is_default_rule,
     ):
         new_id = self._push_rules_enable_id_gen.get_next()
+
+        if not is_default_rule:
+            # first check it exists; we need to lock for key share so that a
+            # transaction that deletes the push rule will conflict with this one.
+            # We also need a push_rule_enable row to exist for every push_rules
+            # row, otherwise it is possible to simultaneously delete a push rule
+            # (that has no _enable row) and enable it, resulting in a dangling
+            # _enable row. To solve this: we either need to use SERIALISABLE or
+            # ensure we always have a push_rule_enable row for every push_rule
+            # row. We chose the latter.
+            for_key_share = "FOR KEY SHARE"
+            if not isinstance(self.database_engine, PostgresEngine):
+                # For key share is not applicable/available on SQLite
+                for_key_share = ""
+            sql = (
+                """
+                SELECT 1 FROM push_rules
+                WHERE user_name = ? AND rule_id = ?
+                %s
+            """
+                % for_key_share
+            )
+            txn.execute(sql, (user_id, rule_id))
+            if txn.fetchone() is None:
+                # needed to set NOT_FOUND code.
+                raise NotFoundError("Push rule does not exist.")
+
         self.db_pool.simple_upsert_txn(
             txn,
             "push_rules_enable",
@@ -606,8 +686,30 @@ class PushRuleStore(PushRulesWorkerStore):
         )
 
     async def set_push_rule_actions(
-        self, user_id, rule_id, actions, is_default_rule
+        self,
+        user_id: str,
+        rule_id: str,
+        actions: List[Union[dict, str]],
+        is_default_rule: bool,
     ) -> None:
+        """
+        Sets the `actions` state of a push rule.
+
+        Will throw NotFoundError if the rule does not exist; the Code for this
+        is NOT_FOUND.
+
+        Args:
+            user_id: the user ID of the user who wishes to enable/disable the rule
+                e.g. '@tina:example.org'
+            rule_id: the full rule ID of the rule to be enabled/disabled
+                e.g. 'global/override/.m.rule.roomnotif'
+                  or 'global/override/myCustomRule'
+            actions: A list of actions (each action being a dict or string),
+                e.g. ["notify", {"set_tweak": "highlight", "value": false}]
+            is_default_rule: True if and only if this is a server-default rule.
+                This skips the check for existence (as only user-created rules
+                are always stored in the database `push_rules` table).
+        """
         actions_json = json_encoder.encode(actions)
 
         def set_push_rule_actions_txn(txn, stream_id, event_stream_ordering):
@@ -629,12 +731,19 @@ class PushRuleStore(PushRulesWorkerStore):
                     update_stream=False,
                 )
             else:
-                self.db_pool.simple_update_one_txn(
-                    txn,
-                    "push_rules",
-                    {"user_name": user_id, "rule_id": rule_id},
-                    {"actions": actions_json},
-                )
+                try:
+                    self.db_pool.simple_update_one_txn(
+                        txn,
+                        "push_rules",
+                        {"user_name": user_id, "rule_id": rule_id},
+                        {"actions": actions_json},
+                    )
+                except StoreError as serr:
+                    if serr.code == 404:
+                        # this sets the NOT_FOUND error Code
+                        raise NotFoundError("Push rule does not exist")
+                    else:
+                        raise
 
             self._insert_push_rules_update_txn(
                 txn,
diff --git a/synapse/storage/databases/main/schema/delta/58/10_pushrules_enabled_delete_obsolete.sql b/synapse/storage/databases/main/schema/delta/58/10_pushrules_enabled_delete_obsolete.sql
new file mode 100644
index 0000000000..847aebd85e
--- /dev/null
+++ b/synapse/storage/databases/main/schema/delta/58/10_pushrules_enabled_delete_obsolete.sql
@@ -0,0 +1,28 @@
+/* Copyright 2020 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.
+ */
+
+/**
+  Delete stuck 'enabled' bits that correspond to deleted or non-existent push rules.
+  We ignore rules that are server-default rules because they are not defined
+  in the `push_rules` table.
+**/
+
+DELETE FROM push_rules_enable WHERE
+  rule_id NOT LIKE 'global/%/.m.rule.%'
+  AND NOT EXISTS (
+    SELECT 1 FROM push_rules
+    WHERE push_rules.user_name = push_rules_enable.user_name
+      AND push_rules.rule_id = push_rules_enable.rule_id
+  );