Add endpoint for sending forwards

synapse/rest/__init__.py

@@ -47,6 +47,7 @@ from synapse.rest.client.v2_alpha import (
     register,
     relations,
     report_event,
+    forward_event,
     room_keys,
     room_upgrade_rest_servlet,
     sendtodevice,
@@ -108,6 +109,7 @@ class ClientRestResource(JsonResource):
         tags.register_servlets(hs, client_resource)
         account_data.register_servlets(hs, client_resource)
         report_event.register_servlets(hs, client_resource)
+        forward_event.register_servlets(hs, client_resource)
         openid.register_servlets(hs, client_resource)
         notifications.register_servlets(hs, client_resource)
         devices.register_servlets(hs, client_resource)

synapse/rest/client/v2_alpha/forward_event.py

@@ -0,0 +1,118 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 Tulir Asokan <tulir@maunium.net>
+#
+# 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 synapse.api.errors import Codes, SynapseError, AuthError
+from synapse.http.servlet import RestServlet, parse_integer
+from synapse.logging.opentracing import set_tag
+
+from ._base import client_patterns
+
+logger = logging.getLogger(__name__)
+
+
+class RoomEventForwardServlet(RestServlet):
+    """
+    PUT /net.maunium.msc2730/rooms/{room_id}/event/{event_id}/forward/{target_room_id}/{txn_id}
+    """
+
+    PATTERNS = client_patterns(
+        ("/net.maunium.msc2730/rooms/(?P<room_id>[^/]*)/event/(?P<event_id>[^/]*)"
+         "/forward/(?P<target_room_id>[^/]*)/(?P<txn_id>.*)"),
+        releases=(),  # This is an unstable feature
+    )
+
+    _data_key = "net.maunium.msc2730.forwarded"
+    _err_not_forwardable = "NET.MAUNIUM.MSC2730_NOT_FORWARDABLE"
+
+    def __init__(self, hs):
+        super().__init__()
+        self.event_creation_handler = hs.get_event_creation_handler()
+        self.event_handler = hs.get_event_handler()
+        self.store = hs.get_datastore()
+        self.auth = hs.get_auth()
+
+    async def on_PUT(self, request, room_id, event_id, target_room_id, txn_id):
+        requester = await self.auth.get_user_by_req(request, allow_guest=True)
+
+        try:
+            event = await self.event_handler.get_event(
+                requester.user, room_id, event_id
+            )
+        except AuthError:
+            event = None
+        if not event:
+            raise SynapseError(404, "Event not found.", errcode=Codes.NOT_FOUND)
+
+        if event.is_state():
+            raise SynapseError(401, "State events cannot be forwarded.",
+                               errcode=self._err_not_forwardable)
+        elif event.redacts:
+            raise SynapseError(401, "Redaction events cannot be forwarded.",
+                               errcode=self._err_not_forwardable)
+        elif event.internal_metadata.is_redacted():
+            raise SynapseError(401, "Redacted events cannot be forwarded.",
+                               errcode=self._err_not_forwardable)
+
+        event_id = event.event_id
+        event_dict = event.get_dict()
+
+        content = event_dict.pop("content")
+        unsigned = event_dict.pop("unsigned", {})
+        event_type = event_dict.pop("type")
+        has_forward_meta = self._data_key in content
+        try:
+            is_valid_forward = has_forward_meta and unsigned[self._data_key]["valid"]
+        except (KeyError, TypeError):
+            is_valid_forward = False
+
+        if has_forward_meta and not is_valid_forward:
+            raise SynapseError(401, "Event contains invalid forward metadata.",
+                               errcode=self._err_not_forwardable)
+        elif not has_forward_meta:
+            content[self._data_key] = event_dict
+            content[self._data_key]["unsigned"] = {
+                "room_version": await self.store.get_room_version(event.room_id),
+                # TODO add sender profile info here
+            }
+
+        forwarded_event_dict = {
+            "type": event_type,
+            "content": content,
+            "room_id": target_room_id,
+            "sender": requester.user.to_string(),
+            "unsigned": {
+                self._data_key: {
+                    "valid": True,
+                    "event_id": event_id,
+                }
+            }
+        }
+
+        if b"ts" in request.args and requester.app_service:
+            forwarded_event_dict["origin_server_ts"] = parse_integer(request, "ts", 0)
+
+        forwarded_event, _ = await self.event_creation_handler.create_and_send_nonmember_event(
+            requester, forwarded_event_dict, txn_id=txn_id
+        )
+
+        set_tag("event_id", forwarded_event.event_id)
+        return 200, {"event_id": forwarded_event.event_id}
+
+
+def register_servlets(hs, http_server):
+    RoomEventForwardServlet(hs).register(http_server)

synapse/rest/client/versions.py

@@ -60,6 +60,8 @@ class VersionsRestServlet(RestServlet):
                     "org.matrix.e2e_cross_signing": True,
                     # Implements additional endpoints as described in MSC2432
                     "org.matrix.msc2432": True,
+                    # Implements endpoint and forwarded event validation as described in MSC2730
+                    "net.maunium.msc2730": True,
                 },
             },
         )