Do not propagate typing notifications from shadow-banned users.

changelog.d/8176.feature

@@ -0,0 +1 @@
+Add support for shadow-banning users (ignoring any message send requests).

synapse/handlers/typing.py

@@ -14,10 +14,11 @@
 # limitations under the License.
 
 import logging
+import random
 from collections import namedtuple
 from typing import TYPE_CHECKING, List, Set, Tuple
 
-from synapse.api.errors import AuthError, SynapseError
+from synapse.api.errors import AuthError, ShadowBanError, SynapseError
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.replication.tcp.streams import TypingStream
 from synapse.types import UserID, get_domain_from_id
@@ -227,16 +228,21 @@ def _handle_timeout_for_member(self, now: int, member: RoomMember):
             self._stopped_typing(member)
             return
 
-    async def started_typing(self, target_user, auth_user, room_id, timeout):
+    async def started_typing(self, target_user, requester, room_id, timeout):
         target_user_id = target_user.to_string()
-        auth_user_id = auth_user.to_string()
+        auth_user_id = requester.user.to_string()
 
         if not self.is_mine_id(target_user_id):
             raise SynapseError(400, "User is not hosted on this homeserver")
 
         if target_user_id != auth_user_id:
             raise AuthError(400, "Cannot set another user's typing state")
 
+        if requester.shadow_banned:
+            # We randomly sleep a bit just to annoy the requester.
+            await self.clock.sleep(random.randint(1, 10))
+            raise ShadowBanError()
+
         await self.auth.check_user_in_room(room_id, target_user_id)
 
         logger.debug("%s has started typing in %s", target_user_id, room_id)
@@ -256,16 +262,21 @@ async def started_typing(self, target_user, auth_user, room_id, timeout):
 
         self._push_update(member=member, typing=True)
 
-    async def stopped_typing(self, target_user, auth_user, room_id):
+    async def stopped_typing(self, target_user, requester, room_id):
         target_user_id = target_user.to_string()
-        auth_user_id = auth_user.to_string()
+        auth_user_id = requester.user.to_string()
 
         if not self.is_mine_id(target_user_id):
             raise SynapseError(400, "User is not hosted on this homeserver")
 
         if target_user_id != auth_user_id:
             raise AuthError(400, "Cannot set another user's typing state")
 
+        if requester.shadow_banned:
+            # We randomly sleep a bit just to annoy the requester.
+            await self.clock.sleep(random.randint(1, 10))
+            raise ShadowBanError()
+
         await self.auth.check_user_in_room(room_id, target_user_id)
 
         logger.debug("%s has stopped typing in %s", target_user_id, room_id)

synapse/rest/client/v1/room.py

@@ -869,17 +869,21 @@ async def on_PUT(self, request, room_id, user_id):
         # Limit timeout to stop people from setting silly typing timeouts.
         timeout = min(content.get("timeout", 30000), 120000)
 
-        if content["typing"]:
-            await self.typing_handler.started_typing(
-                target_user=target_user,
-                auth_user=requester.user,
-                room_id=room_id,
-                timeout=timeout,
-            )
-        else:
-            await self.typing_handler.stopped_typing(
-                target_user=target_user, auth_user=requester.user, room_id=room_id
-            )
+        try:
+            if content["typing"]:
+                await self.typing_handler.started_typing(
+                    target_user=target_user,
+                    requester=requester,
+                    room_id=room_id,
+                    timeout=timeout,
+                )
+            else:
+                await self.typing_handler.stopped_typing(
+                    target_user=target_user, requester=requester, room_id=room_id
+                )
+        except ShadowBanError:
+            # Pretend this worked without error.
+            pass
 
         return 200, {}
 

tests/handlers/test_typing.py

@@ -21,7 +21,7 @@
 from twisted.internet import defer
 
 from synapse.api.errors import AuthError
-from synapse.types import UserID
+from synapse.types import UserID, create_requester
 
 from tests import unittest
 from tests.test_utils import make_awaitable
@@ -167,7 +167,10 @@ def test_started_typing_local(self):
 
         self.get_success(
             self.handler.started_typing(
-                target_user=U_APPLE, auth_user=U_APPLE, room_id=ROOM_ID, timeout=20000
+                target_user=U_APPLE,
+                requester=create_requester(U_APPLE),
+                room_id=ROOM_ID,
+                timeout=20000,
             )
         )
 
@@ -194,7 +197,10 @@ def test_started_typing_remote_send(self):
 
         self.get_success(
             self.handler.started_typing(
-                target_user=U_APPLE, auth_user=U_APPLE, room_id=ROOM_ID, timeout=20000
+                target_user=U_APPLE,
+                requester=create_requester(U_APPLE),
+                room_id=ROOM_ID,
+                timeout=20000,
             )
         )
 
@@ -269,7 +275,9 @@ def test_stopped_typing(self):
 
         self.get_success(
             self.handler.stopped_typing(
-                target_user=U_APPLE, auth_user=U_APPLE, room_id=ROOM_ID
+                target_user=U_APPLE,
+                requester=create_requester(U_APPLE),
+                room_id=ROOM_ID,
             )
         )
 
@@ -309,7 +317,10 @@ def test_typing_timeout(self):
 
         self.get_success(
             self.handler.started_typing(
-                target_user=U_APPLE, auth_user=U_APPLE, room_id=ROOM_ID, timeout=10000
+                target_user=U_APPLE,
+                requester=create_requester(U_APPLE),
+                room_id=ROOM_ID,
+                timeout=10000,
             )
         )
 
@@ -348,7 +359,10 @@ def test_typing_timeout(self):
 
         self.get_success(
             self.handler.started_typing(
-                target_user=U_APPLE, auth_user=U_APPLE, room_id=ROOM_ID, timeout=10000
+                target_user=U_APPLE,
+                requester=create_requester(U_APPLE),
+                room_id=ROOM_ID,
+                timeout=10000,
             )
         )
 

tests/rest/client/test_shadow_banned.py

@@ -179,6 +179,54 @@ def test_upgrade(self):
         # The summary should be empty since the room doesn't exist.
         self.assertEqual(summary, {})
 
+    def test_typing(self):
+        """Typing notifications should not be propagated into the room."""
+        # The create works fine.
+        room_id = self.helper.create_room_as(
+            self.banned_user_id, tok=self.banned_access_token
+        )
+
+        request, channel = self.make_request(
+            "PUT",
+            "/rooms/%s/typing/%s" % (room_id, self.banned_user_id),
+            {"typing": True, "timeout": 30000},
+            access_token=self.banned_access_token,
+        )
+        self.render(request)
+        self.assertEquals(200, channel.code)
+
+        # There should be no typing events.
+        event_source = self.hs.get_event_sources().sources["typing"]
+        self.assertEquals(event_source.get_current_key(), 0)
+
+        # The other user can join and sending typing events.
+        self.helper.join(room_id, self.other_user_id, tok=self.other_access_token)
+
+        request, channel = self.make_request(
+            "PUT",
+            "/rooms/%s/typing/%s" % (room_id, self.other_user_id),
+            {"typing": True, "timeout": 30000},
+            access_token=self.other_access_token,
+        )
+        self.render(request)
+        self.assertEquals(200, channel.code)
+
+        # These appear in the room.
+        self.assertEquals(event_source.get_current_key(), 1)
+        events = self.get_success(
+            event_source.get_new_events(from_key=0, room_ids=[room_id])
+        )
+        self.assertEquals(
+            events[0],
+            [
+                {
+                    "type": "m.typing",
+                    "room_id": room_id,
+                    "content": {"user_ids": [self.other_user_id]},
+                }
+            ],
+        )
+
 
 # To avoid the tests timing out don't add a delay to "annoy the requester".
 @patch("random.randint", new=lambda a, b: 0)