Implement MSC2659: application service ping endpoint (#15249)

Signed-off-by: Tulir Asokan <tulir@maunium.net>

synapse/rest/client/appservice_ping.py

@@ -0,0 +1,115 @@
+# Copyright 2023 Tulir Asokan
+#
+# 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
+import time
+from http import HTTPStatus
+from typing import TYPE_CHECKING, Any, Dict, Tuple
+
+from synapse.api.errors import (
+    CodeMessageException,
+    Codes,
+    HttpResponseException,
+    SynapseError,
+)
+from synapse.http import RequestTimedOutError
+from synapse.http.server import HttpServer
+from synapse.http.servlet import RestServlet, parse_json_object_from_request
+from synapse.http.site import SynapseRequest
+from synapse.types import JsonDict
+
+from ._base import client_patterns
+
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+
+logger = logging.getLogger(__name__)
+
+
+class AppservicePingRestServlet(RestServlet):
+    PATTERNS = client_patterns(
+        "/fi.mau.msc2659/appservice/(?P<appservice_id>[^/]*)/ping",
+        unstable=True,
+        releases=(),
+    )
+
+    def __init__(self, hs: "HomeServer"):
+        super().__init__()
+        self.as_api = hs.get_application_service_api()
+        self.auth = hs.get_auth()
+
+    async def on_POST(
+        self, request: SynapseRequest, appservice_id: str
+    ) -> Tuple[int, JsonDict]:
+        requester = await self.auth.get_user_by_req(request)
+
+        if not requester.app_service:
+            raise SynapseError(
+                HTTPStatus.FORBIDDEN,
+                "Only application services can use the /appservice/ping endpoint",
+                Codes.FORBIDDEN,
+            )
+        elif requester.app_service.id != appservice_id:
+            raise SynapseError(
+                HTTPStatus.FORBIDDEN,
+                "Mismatching application service ID in path",
+                Codes.FORBIDDEN,
+            )
+        elif not requester.app_service.url:
+            raise SynapseError(
+                HTTPStatus.BAD_REQUEST,
+                "The application service does not have a URL set",
+                Codes.AS_PING_URL_NOT_SET,
+            )
+
+        content = parse_json_object_from_request(request)
+        txn_id = content.get("transaction_id", None)
+
+        start = time.monotonic()
+        try:
+            await self.as_api.ping(requester.app_service, txn_id)
+        except RequestTimedOutError as e:
+            raise SynapseError(
+                HTTPStatus.GATEWAY_TIMEOUT,
+                e.msg,
+                Codes.AS_PING_CONNECTION_TIMEOUT,
+            )
+        except CodeMessageException as e:
+            additional_fields: Dict[str, Any] = {"status": e.code}
+            if isinstance(e, HttpResponseException):
+                try:
+                    additional_fields["body"] = e.response.decode("utf-8")
+                except UnicodeDecodeError:
+                    pass
+            raise SynapseError(
+                HTTPStatus.BAD_GATEWAY,
+                f"HTTP {e.code} {e.msg}",
+                Codes.AS_PING_BAD_STATUS,
+                additional_fields=additional_fields,
+            )
+        except Exception as e:
+            raise SynapseError(
+                HTTPStatus.BAD_GATEWAY,
+                f"{type(e).__name__}: {e}",
+                Codes.AS_PING_CONNECTION_FAILED,
+            )
+
+        duration = time.monotonic() - start
+
+        return HTTPStatus.OK, {"duration": int(duration * 1000)}
+
+
+def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
+    if hs.config.experimental.msc2659_enabled:
+        AppservicePingRestServlet(hs).register(http_server)