Add report room API (MSC4151) (#17270)

https://github.com/matrix-org/matrix-spec-proposals/pull/4151

This is intended to be enabled by default for immediate use. When FCP is
complete, the unstable endpoint will be dropped and stable endpoint
supported instead - no backwards compatibility is expected for the
unstable endpoint.

9 files changed, 210 insertions, 8 deletions

diff --git a/changelog.d/17270.feature b/changelog.d/17270.feature
new file mode 100644
index 0000000000..4ea5e7be85
--- /dev/null
+++ b/changelog.d/17270.feature
@@ -0,0 +1 @@
+Add support for the unstable [MSC4151](https://github.com/matrix-org/matrix-spec-proposals/pull/4151) report room API.
diff --git a/synapse/config/experimental.py b/synapse/config/experimental.py
index 75fe6d7b24..5fe5b951dd 100644
--- a/synapse/config/experimental.py
+++ b/synapse/config/experimental.py
@@ -443,3 +443,6 @@ class ExperimentalConfig(Config):
         self.msc3916_authenticated_media_enabled = experimental.get(
             "msc3916_authenticated_media_enabled", False
         )
+
+        # MSC4151: Report room API (Client-Server API)
+        self.msc4151_enabled: bool = experimental.get("msc4151_enabled", False)
diff --git a/synapse/rest/__init__.py b/synapse/rest/__init__.py
index 534dc0e276..0024ccf708 100644
--- a/synapse/rest/__init__.py
+++ b/synapse/rest/__init__.py
@@ -53,7 +53,7 @@ from synapse.rest.client import (
     register,
     relations,
     rendezvous,
-    report_event,
+    reporting,
     room,
     room_keys,
     room_upgrade_rest_servlet,
@@ -128,7 +128,7 @@ class ClientRestResource(JsonResource):
         tags.register_servlets(hs, client_resource)
         account_data.register_servlets(hs, client_resource)
         if is_main_process:
-            report_event.register_servlets(hs, client_resource)
+            reporting.register_servlets(hs, client_resource)
             openid.register_servlets(hs, client_resource)
         notifications.register_servlets(hs, client_resource)
         devices.register_servlets(hs, client_resource)
diff --git a/synapse/rest/client/report_event.py b/synapse/rest/client/reporting.py
index 447281931e..a95b83b14d 100644
--- a/synapse/rest/client/report_event.py
+++ b/synapse/rest/client/reporting.py
@@ -23,17 +23,28 @@ import logging
 from http import HTTPStatus
 from typing import TYPE_CHECKING, Tuple
 
+from synapse._pydantic_compat import HAS_PYDANTIC_V2
 from synapse.api.errors import AuthError, Codes, NotFoundError, SynapseError
 from synapse.http.server import HttpServer
-from synapse.http.servlet import RestServlet, parse_json_object_from_request
+from synapse.http.servlet import (
+    RestServlet,
+    parse_and_validate_json_object_from_request,
+    parse_json_object_from_request,
+)
 from synapse.http.site import SynapseRequest
 from synapse.types import JsonDict
+from synapse.types.rest import RequestBodyModel
 
 from ._base import client_patterns
 
 if TYPE_CHECKING:
     from synapse.server import HomeServer
 
+if TYPE_CHECKING or HAS_PYDANTIC_V2:
+    from pydantic.v1 import StrictStr
+else:
+    from pydantic import StrictStr
+
 logger = logging.getLogger(__name__)
 
 
@@ -95,5 +106,49 @@ class ReportEventRestServlet(RestServlet):
         return 200, {}
 
 
+class ReportRoomRestServlet(RestServlet):
+    # https://github.com/matrix-org/matrix-spec-proposals/pull/4151
+    PATTERNS = client_patterns(
+        "/org.matrix.msc4151/rooms/(?P<room_id>[^/]*)/report$",
+        releases=[],
+        v1=False,
+        unstable=True,
+    )
+
+    def __init__(self, hs: "HomeServer"):
+        super().__init__()
+        self.hs = hs
+        self.auth = hs.get_auth()
+        self.clock = hs.get_clock()
+        self.store = hs.get_datastores().main
+
+    class PostBody(RequestBodyModel):
+        reason: StrictStr
+
+    async def on_POST(
+        self, request: SynapseRequest, room_id: str
+    ) -> Tuple[int, JsonDict]:
+        requester = await self.auth.get_user_by_req(request)
+        user_id = requester.user.to_string()
+
+        body = parse_and_validate_json_object_from_request(request, self.PostBody)
+
+        room = await self.store.get_room(room_id)
+        if room is None:
+            raise NotFoundError("Room does not exist")
+
+        await self.store.add_room_report(
+            room_id=room_id,
+            user_id=user_id,
+            reason=body.reason,
+            received_ts=self.clock.time_msec(),
+        )
+
+        return 200, {}
+
+
 def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     ReportEventRestServlet(hs).register(http_server)
+
+    if hs.config.experimental.msc4151_enabled:
+        ReportRoomRestServlet(hs).register(http_server)
diff --git a/synapse/rest/client/versions.py b/synapse/rest/client/versions.py
index 56de6906d0..f428158139 100644
--- a/synapse/rest/client/versions.py
+++ b/synapse/rest/client/versions.py
@@ -149,6 +149,8 @@ class VersionsRestServlet(RestServlet):
                             is not None
                         )
                     ),
+                    # MSC4151: Report room API (Client-Server API)
+                    "org.matrix.msc4151": self.config.experimental.msc4151_enabled,
                 },
             },
         )
diff --git a/synapse/storage/databases/main/room.py b/synapse/storage/databases/main/room.py
index 616c941687..b8a71c803e 100644
--- a/synapse/storage/databases/main/room.py
+++ b/synapse/storage/databases/main/room.py
@@ -2207,6 +2207,7 @@ class RoomStore(RoomBackgroundUpdateStore, RoomWorkerStore):
         super().__init__(database, db_conn, hs)
 
         self._event_reports_id_gen = IdGenerator(db_conn, "event_reports", "id")
+        self._room_reports_id_gen = IdGenerator(db_conn, "room_reports", "id")
 
         self._instance_name = hs.get_instance_name()
 
@@ -2416,6 +2417,37 @@ class RoomStore(RoomBackgroundUpdateStore, RoomWorkerStore):
         )
         return next_id
 
+    async def add_room_report(
+        self,
+        room_id: str,
+        user_id: str,
+        reason: str,
+        received_ts: int,
+    ) -> int:
+        """Add a room report
+
+        Args:
+            room_id: The room ID being reported.
+            user_id: User who reports the room.
+            reason: Description that the user specifies.
+            received_ts: Time when the user submitted the report (milliseconds).
+        Returns:
+            Id of the room report.
+        """
+        next_id = self._room_reports_id_gen.get_next()
+        await self.db_pool.simple_insert(
+            table="room_reports",
+            values={
+                "id": next_id,
+                "received_ts": received_ts,
+                "room_id": room_id,
+                "user_id": user_id,
+                "reason": reason,
+            },
+            desc="add_room_report",
+        )
+        return next_id
+
     async def block_room(self, room_id: str, user_id: str) -> None:
         """Marks the room as blocked.
 
diff --git a/synapse/storage/schema/main/delta/85/06_add_room_reports.sql b/synapse/storage/schema/main/delta/85/06_add_room_reports.sql
new file mode 100644
index 0000000000..f7b45276cf
--- /dev/null
+++ b/synapse/storage/schema/main/delta/85/06_add_room_reports.sql
@@ -0,0 +1,20 @@
+--
+-- This file is licensed under the Affero General Public License (AGPL) version 3.
+--
+-- Copyright (C) 2024 New Vector, Ltd
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU Affero General Public License as
+-- published by the Free Software Foundation, either version 3 of the
+-- License, or (at your option) any later version.
+--
+-- See the GNU Affero General Public License for more details:
+-- <https://www.gnu.org/licenses/agpl-3.0.html>.
+
+CREATE TABLE room_reports (
+    id BIGINT NOT NULL PRIMARY KEY,
+    received_ts BIGINT NOT NULL,
+    room_id TEXT NOT NULL,
+    user_id TEXT NOT NULL,
+    reason TEXT NOT NULL
+);
diff --git a/tests/rest/admin/test_event_reports.py b/tests/rest/admin/test_event_reports.py
index a0f978911a..feb410a11d 100644
--- a/tests/rest/admin/test_event_reports.py
+++ b/tests/rest/admin/test_event_reports.py
@@ -24,7 +24,7 @@ from twisted.test.proto_helpers import MemoryReactor
 
 import synapse.rest.admin
 from synapse.api.errors import Codes
-from synapse.rest.client import login, report_event, room
+from synapse.rest.client import login, reporting, room
 from synapse.server import HomeServer
 from synapse.types import JsonDict
 from synapse.util import Clock
@@ -37,7 +37,7 @@ class EventReportsTestCase(unittest.HomeserverTestCase):
         synapse.rest.admin.register_servlets,
         login.register_servlets,
         room.register_servlets,
-        report_event.register_servlets,
+        reporting.register_servlets,
     ]
 
     def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
@@ -453,7 +453,7 @@ class EventReportDetailTestCase(unittest.HomeserverTestCase):
         synapse.rest.admin.register_servlets,
         login.register_servlets,
         room.register_servlets,
-        report_event.register_servlets,
+        reporting.register_servlets,
     ]
 
     def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
diff --git a/tests/rest/client/test_report_event.py b/tests/rest/client/test_reporting.py
index 5903771e52..009deb9cb0 100644
--- a/tests/rest/client/test_report_event.py
+++ b/tests/rest/client/test_reporting.py
@@ -22,7 +22,7 @@
 from twisted.test.proto_helpers import MemoryReactor
 
 import synapse.rest.admin
-from synapse.rest.client import login, report_event, room
+from synapse.rest.client import login, reporting, room
 from synapse.server import HomeServer
 from synapse.types import JsonDict
 from synapse.util import Clock
@@ -35,7 +35,7 @@ class ReportEventTestCase(unittest.HomeserverTestCase):
         synapse.rest.admin.register_servlets,
         login.register_servlets,
         room.register_servlets,
-        report_event.register_servlets,
+        reporting.register_servlets,
     ]
 
     def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
@@ -139,3 +139,92 @@ class ReportEventTestCase(unittest.HomeserverTestCase):
             "POST", self.report_path, data, access_token=self.other_user_tok
         )
         self.assertEqual(response_status, channel.code, msg=channel.result["body"])
+
+
+class ReportRoomTestCase(unittest.HomeserverTestCase):
+    servlets = [
+        synapse.rest.admin.register_servlets,
+        login.register_servlets,
+        room.register_servlets,
+        reporting.register_servlets,
+    ]
+
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
+        self.other_user = self.register_user("user", "pass")
+        self.other_user_tok = self.login("user", "pass")
+
+        self.room_id = self.helper.create_room_as(
+            self.other_user, tok=self.other_user_tok, is_public=True
+        )
+        self.report_path = (
+            f"/_matrix/client/unstable/org.matrix.msc4151/rooms/{self.room_id}/report"
+        )
+
+    @unittest.override_config(
+        {
+            "experimental_features": {"msc4151_enabled": True},
+        }
+    )
+    def test_reason_str(self) -> None:
+        data = {"reason": "this makes me sad"}
+        self._assert_status(200, data)
+
+    @unittest.override_config(
+        {
+            "experimental_features": {"msc4151_enabled": True},
+        }
+    )
+    def test_no_reason(self) -> None:
+        data = {"not_reason": "for typechecking"}
+        self._assert_status(400, data)
+
+    @unittest.override_config(
+        {
+            "experimental_features": {"msc4151_enabled": True},
+        }
+    )
+    def test_reason_nonstring(self) -> None:
+        data = {"reason": 42}
+        self._assert_status(400, data)
+
+    @unittest.override_config(
+        {
+            "experimental_features": {"msc4151_enabled": True},
+        }
+    )
+    def test_reason_null(self) -> None:
+        data = {"reason": None}
+        self._assert_status(400, data)
+
+    @unittest.override_config(
+        {
+            "experimental_features": {"msc4151_enabled": True},
+        }
+    )
+    def test_cannot_report_nonexistent_room(self) -> None:
+        """
+        Tests that we don't accept event reports for rooms which do not exist.
+        """
+        channel = self.make_request(
+            "POST",
+            "/_matrix/client/unstable/org.matrix.msc4151/rooms/!bloop:example.org/report",
+            {"reason": "i am very sad"},
+            access_token=self.other_user_tok,
+            shorthand=False,
+        )
+        self.assertEqual(404, channel.code, msg=channel.result["body"])
+        self.assertEqual(
+            "Room does not exist",
+            channel.json_body["error"],
+            msg=channel.result["body"],
+        )
+
+    def _assert_status(self, response_status: int, data: JsonDict) -> None:
+        channel = self.make_request(
+            "POST",
+            self.report_path,
+            data,
+            access_token=self.other_user_tok,
+            shorthand=False,
+        )
+        self.assertEqual(response_status, channel.code, msg=channel.result["body"])