Merge branch 'develop' of github.com:matrix-org/synapse into develop

Conflicts:
	synapse/http/client.py

1 files changed, 22 insertions, 4 deletions

diff --git a/synapse/http/client.py b/synapse/http/client.py

index 5a5e40a26e..ebf1aa47c4 100644
--- a/synapse/http/client.py
+++ b/synapse/http/client.py
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-# Copyright 2014 matrix.org
+# Copyright 2014 OpenMarket Ltd
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -15,6 +15,7 @@
 
 
 from twisted.internet import defer, reactor
+from twisted.internet.error import DNSLookupError
 from twisted.web.client import _AgentBase, _URI, readBody, FileBodyProducer
 from twisted.web.http_headers import Headers
 
@@ -23,7 +24,7 @@ from synapse.util.async import sleep
 
 from syutil.jsonutil import encode_canonical_json
 
-from synapse.api.errors import CodeMessageException
+from synapse.api.errors import CodeMessageException, SynapseError
 
 from StringIO import StringIO
 
@@ -45,6 +46,7 @@ _destination_mappings = {
 class HttpClient(object):
     """ Interface for talking json over http
     """
+    RETRY_DNS_LOOKUP_FAILURES = "__retry_dns"
 
     def put_json(self, destination, path, data):
         """ Sends the specifed json data using PUT
@@ -144,13 +146,23 @@ class TwistedHttpClient(HttpClient):
             destination = _destination_mappings[destination]
 
         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)
 
         response = yield self._create_request(
             destination.encode("ascii"),
             "GET",
             path.encode("ascii"),
-            query_bytes=query_bytes
+            query_bytes=query_bytes,
+            retry_on_dns_fail=retry_on_dns_fail
         )
 
         body = yield readBody(response)
@@ -179,7 +191,8 @@ class TwistedHttpClient(HttpClient):
 
     @defer.inlineCallbacks
     def _create_request(self, destination, method, path_bytes, param_bytes=b"",
-                        query_bytes=b"", producer=None, headers_dict={}):
+                        query_bytes=b"", producer=None, headers_dict={},
+                        retry_on_dns_fail=True):
         """ Creates and sends a request to the given url
         """
         headers_dict[b"User-Agent"] = [b"Synapse"]
@@ -218,6 +231,11 @@ class TwistedHttpClient(HttpClient):
                 logger.debug("Got response to %s", method)
                 break
             except Exception as e:
+                if not retry_on_dns_fail and isinstance(e, DNSLookupError):
+                    logger.warn("DNS Lookup failed to %s with %s", destination,
+                                e)
+                    raise SynapseError(400, "Domain specified not found.")
+
                 logger.exception("Got error in _create_request")
                 _print_ex(e)