Use servlets for /key/ endpoints. (#14229)

To fix the response for unknown endpoints under that prefix.

See MSC3743.

synapse/rest/key/v2/remote_key_resource.py

@@ -13,15 +13,20 @@
 # limitations under the License.
 
 import logging
-from typing import TYPE_CHECKING, Dict, Set
+import re
+from typing import TYPE_CHECKING, Dict, Optional, Set, Tuple
 
 from signedjson.sign import sign_json
 
-from synapse.api.errors import Codes, SynapseError
+from twisted.web.server import Request
+
 from synapse.crypto.keyring import ServerKeyFetcher
-from synapse.http.server import DirectServeJsonResource, respond_with_json
-from synapse.http.servlet import parse_integer, parse_json_object_from_request
-from synapse.http.site import SynapseRequest
+from synapse.http.server import HttpServer
+from synapse.http.servlet import (
+    RestServlet,
+    parse_integer,
+    parse_json_object_from_request,
+)
 from synapse.types import JsonDict
 from synapse.util import json_decoder
 from synapse.util.async_helpers import yieldable_gather_results
@@ -32,7 +37,7 @@ if TYPE_CHECKING:
 logger = logging.getLogger(__name__)
 
 
-class RemoteKey(DirectServeJsonResource):
+class RemoteKey(RestServlet):
     """HTTP resource for retrieving the TLS certificate and NACL signature
     verification keys for a collection of servers. Checks that the reported
     X.509 TLS certificate matches the one used in the HTTPS connection. Checks
@@ -88,11 +93,7 @@ class RemoteKey(DirectServeJsonResource):
     }
     """
 
-    isLeaf = True
-
     def __init__(self, hs: "HomeServer"):
-        super().__init__()
-
         self.fetcher = ServerKeyFetcher(hs)
         self.store = hs.get_datastores().main
         self.clock = hs.get_clock()
@@ -101,36 +102,48 @@ class RemoteKey(DirectServeJsonResource):
         )
         self.config = hs.config
 
-    async def _async_render_GET(self, request: SynapseRequest) -> None:
-        assert request.postpath is not None
-        if len(request.postpath) == 1:
-            (server,) = request.postpath
-            query: dict = {server.decode("ascii"): {}}
-        elif len(request.postpath) == 2:
-            server, key_id = request.postpath
+    def register(self, http_server: HttpServer) -> None:
+        http_server.register_paths(
+            "GET",
+            (
+                re.compile(
+                    "^/_matrix/key/v2/query/(?P<server>[^/]*)(/(?P<key_id>[^/]*))?$"
+                ),
+            ),
+            self.on_GET,
+            self.__class__.__name__,
+        )
+        http_server.register_paths(
+            "POST",
+            (re.compile("^/_matrix/key/v2/query$"),),
+            self.on_POST,
+            self.__class__.__name__,
+        )
+
+    async def on_GET(
+        self, request: Request, server: str, key_id: Optional[str] = None
+    ) -> Tuple[int, JsonDict]:
+        if server and key_id:
             minimum_valid_until_ts = parse_integer(request, "minimum_valid_until_ts")
             arguments = {}
             if minimum_valid_until_ts is not None:
                 arguments["minimum_valid_until_ts"] = minimum_valid_until_ts
-            query = {server.decode("ascii"): {key_id.decode("ascii"): arguments}}
+            query = {server: {key_id: arguments}}
         else:
-            raise SynapseError(404, "Not found %r" % request.postpath, Codes.NOT_FOUND)
+            query = {server: {}}
 
-        await self.query_keys(request, query, query_remote_on_cache_miss=True)
+        return 200, await self.query_keys(query, query_remote_on_cache_miss=True)
 
-    async def _async_render_POST(self, request: SynapseRequest) -> None:
+    async def on_POST(self, request: Request) -> Tuple[int, JsonDict]:
         content = parse_json_object_from_request(request)
 
         query = content["server_keys"]
 
-        await self.query_keys(request, query, query_remote_on_cache_miss=True)
+        return 200, await self.query_keys(query, query_remote_on_cache_miss=True)
 
     async def query_keys(
-        self,
-        request: SynapseRequest,
-        query: JsonDict,
-        query_remote_on_cache_miss: bool = False,
-    ) -> None:
+        self, query: JsonDict, query_remote_on_cache_miss: bool = False
+    ) -> JsonDict:
         logger.info("Handling query for keys %r", query)
 
         store_queries = []
@@ -232,7 +245,7 @@ class RemoteKey(DirectServeJsonResource):
                     for server_name, keys in cache_misses.items()
                 ),
             )
-            await self.query_keys(request, query, query_remote_on_cache_miss=False)
+            return await self.query_keys(query, query_remote_on_cache_miss=False)
         else:
             signed_keys = []
             for key_json_raw in json_results:
@@ -244,6 +257,4 @@ class RemoteKey(DirectServeJsonResource):
 
                 signed_keys.append(key_json)
 
-            response = {"server_keys": signed_keys}
-
-            respond_with_json(request, 200, response, canonical_json=True)
+            return {"server_keys": signed_keys}