Add a keyword argument to get_json to avoid retrying on DNS failures. Rather than passing MatrixHttpClient.RETRY_DNS_LOOKUP_FAILURES as a fake query string parameter

synapse/federation/replication.py

@@ -159,7 +159,8 @@ class ReplicationLayer(object):
         return defer.succeed(None)
 
     @log_function
-    def make_query(self, destination, query_type, args):
+    def make_query(self, destination, query_type, args,
+                   retry_on_dns_fail=True):
         """Sends a federation Query to a remote homeserver of the given type
         and arguments.
 
@@ -174,7 +175,9 @@ class ReplicationLayer(object):
             a Deferred which will eventually yield a JSON object from the
             response
         """
-        return self.transport_layer.make_query(destination, query_type, args)
+        return self.transport_layer.make_query(
+            destination, query_type, args, retry_on_dns_fail=retry_on_dns_fail
+        )
 
     @defer.inlineCallbacks
     @log_function

synapse/federation/transport.py

@@ -193,13 +193,14 @@ class TransportLayer(object):
 
     @defer.inlineCallbacks
     @log_function
-    def make_query(self, destination, query_type, args):
+    def make_query(self, destination, query_type, args, retry_on_dns_fail):
         path = PREFIX + "/query/%s" % query_type
 
         response = yield self.client.get_json(
             destination=destination,
             path=path,
-            args=args
+            args=args,
+            retry_on_dns_fail=retry_on_dns_fail,
         )
 
         defer.returnValue(response)

synapse/handlers/directory.py

@@ -18,7 +18,6 @@ from twisted.internet import defer
 from ._base import BaseHandler
 
 from synapse.api.errors import SynapseError
-from synapse.http.client import MatrixHttpClient
 from synapse.api.events.room import RoomAliasesEvent
 
 import logging
@@ -98,8 +97,8 @@ class DirectoryHandler(BaseHandler):
                 query_type="directory",
                 args={
                     "room_alias": room_alias.to_string(),
-                    MatrixHttpClient.RETRY_DNS_LOOKUP_FAILURES: False
-                }
+                },
+                retry_on_dns_fail=False,
             )
 
             if result and "room_id" in result and "servers" in result:

synapse/http/client.py

@@ -183,7 +183,7 @@ class MatrixHttpClient(BaseHttpClient):
         defer.returnValue((response.code, body))
 
     @defer.inlineCallbacks
-    def get_json(self, destination, path, args={}):
+    def get_json(self, destination, path, args={}, retry_on_dns_fail=True):
         """ Get's some json from the given host homeserver and path
 
         Args:
@@ -203,13 +203,6 @@ class MatrixHttpClient(BaseHttpClient):
         """
         logger.debug("get_json args: %s", args)
 
-        retry_on_dns_fail = True
-        if HttpClient.RETRY_DNS_LOOKUP_FAILURES in args:
-            # FIXME: This isn't ideal, but the interface exposed in get_json
-            # isn't comprehensive enough to give caller's any control over
-            # their connection mechanics.
-            retry_on_dns_fail = args.pop(HttpClient.RETRY_DNS_LOOKUP_FAILURES)
-
         query_bytes = urllib.urlencode(args, True)
         logger.debug("Query bytes: %s Retry DNS: %s", args, retry_on_dns_fail)
 

tests/federation/test_federation.py

@@ -253,7 +253,7 @@ class FederationTestCase(unittest.TestCase):
         response = yield self.federation.make_query(
             destination="remote",
             query_type="a-question",
-            args={"one": "1", "two": "2"}
+            args={"one": "1", "two": "2"},
         )
 
         self.assertEquals({"your": "response"}, response)
@@ -261,7 +261,8 @@ class FederationTestCase(unittest.TestCase):
         self.mock_http_client.get_json.assert_called_with(
             destination="remote",
             path="/_matrix/federation/v1/query/a-question",
-            args={"one": "1", "two": "2"}
+            args={"one": "1", "two": "2"},
+            retry_on_dns_fail=True,
         )
 
     @defer.inlineCallbacks

tests/handlers/test_directory.py

@@ -20,7 +20,6 @@ from twisted.internet import defer
 from mock import Mock
 
 from synapse.server import HomeServer
-from synapse.http.client import MatrixHttpClient
 from synapse.handlers.directory import DirectoryHandler
 from synapse.storage.directory import RoomAliasMapping
 
@@ -95,8 +94,8 @@ class DirectoryTestCase(unittest.TestCase):
             query_type="directory",
             args={
                 "room_alias": "#another:remote",
-                MatrixHttpClient.RETRY_DNS_LOOKUP_FAILURES: False
-            }
+            },
+            retry_on_dns_fail=False,
         )
 
     @defer.inlineCallbacks