Merge branch 'develop' into m-heroes-empty-room-name

4 files changed, 97 insertions, 7 deletions

diff --git a/synapse/app/_base.py b/synapse/app/_base.py
index d4c6c4c8e2..8cc990399f 100644
--- a/synapse/app/_base.py
+++ b/synapse/app/_base.py
@@ -22,13 +22,14 @@ import traceback
 import psutil
 from daemonize import Daemonize
 
-from twisted.internet import error, reactor
+from twisted.internet import defer, error, reactor
 from twisted.protocols.tls import TLSMemoryBIOFactory
 
 import synapse
 from synapse.app import check_bind_error
 from synapse.crypto import context_factory
 from synapse.util import PreserveLoggingContext
+from synapse.util.async_helpers import Linearizer
 from synapse.util.rlimit import change_resource_limit
 from synapse.util.versionstring import get_version_string
 
@@ -99,6 +100,8 @@ def start_reactor(
         logger (logging.Logger): logger instance to pass to Daemonize
     """
 
+    install_dns_limiter(reactor)
+
     def run():
         # make sure that we run the reactor with the sentinel log context,
         # otherwise other PreserveLoggingContext instances will get confused
@@ -312,3 +315,87 @@ def setup_sentry(hs):
         name = hs.config.worker_name if hs.config.worker_name else "master"
         scope.set_tag("worker_app", app)
         scope.set_tag("worker_name", name)
+
+
+def install_dns_limiter(reactor, max_dns_requests_in_flight=100):
+    """Replaces the resolver with one that limits the number of in flight DNS
+    requests.
+
+    This is to workaround https://twistedmatrix.com/trac/ticket/9620, where we
+    can run out of file descriptors and infinite loop if we attempt to do too
+    many DNS queries at once
+    """
+    new_resolver = _LimitedHostnameResolver(
+        reactor.nameResolver, max_dns_requests_in_flight,
+    )
+
+    reactor.installNameResolver(new_resolver)
+
+
+class _LimitedHostnameResolver(object):
+    """Wraps a IHostnameResolver, limiting the number of in-flight DNS lookups.
+    """
+
+    def __init__(self, resolver, max_dns_requests_in_flight):
+        self._resolver = resolver
+        self._limiter = Linearizer(
+            name="dns_client_limiter", max_count=max_dns_requests_in_flight,
+        )
+
+    def resolveHostName(self, resolutionReceiver, hostName, portNumber=0,
+                        addressTypes=None, transportSemantics='TCP'):
+        # We need this function to return `resolutionReceiver` so we do all the
+        # actual logic involving deferreds in a separate function.
+
+        # even though this is happening within the depths of twisted, we need to drop
+        # our logcontext before starting _resolve, otherwise: (a) _resolve will drop
+        # the logcontext if it returns an incomplete deferred; (b) _resolve will
+        # call the resolutionReceiver *with* a logcontext, which it won't be expecting.
+        with PreserveLoggingContext():
+            self._resolve(
+                resolutionReceiver,
+                hostName,
+                portNumber,
+                addressTypes,
+                transportSemantics,
+            )
+
+        return resolutionReceiver
+
+    @defer.inlineCallbacks
+    def _resolve(self, resolutionReceiver, hostName, portNumber=0,
+                 addressTypes=None, transportSemantics='TCP'):
+
+        with (yield self._limiter.queue(())):
+            # resolveHostName doesn't return a Deferred, so we need to hook into
+            # the receiver interface to get told when resolution has finished.
+
+            deferred = defer.Deferred()
+            receiver = _DeferredResolutionReceiver(resolutionReceiver, deferred)
+
+            self._resolver.resolveHostName(
+                receiver, hostName, portNumber,
+                addressTypes, transportSemantics,
+            )
+
+            yield deferred
+
+
+class _DeferredResolutionReceiver(object):
+    """Wraps a IResolutionReceiver and simply resolves the given deferred when
+    resolution is complete
+    """
+
+    def __init__(self, receiver, deferred):
+        self._receiver = receiver
+        self._deferred = deferred
+
+    def resolutionBegan(self, resolutionInProgress):
+        self._receiver.resolutionBegan(resolutionInProgress)
+
+    def addressResolved(self, address):
+        self._receiver.addressResolved(address)
+
+    def resolutionComplete(self):
+        self._deferred.callback(())
+        self._receiver.resolutionComplete()
diff --git a/synapse/app/client_reader.py b/synapse/app/client_reader.py
index 864f1eac48..a16e037f32 100644
--- a/synapse/app/client_reader.py
+++ b/synapse/app/client_reader.py
@@ -38,6 +38,7 @@ from synapse.replication.slave.storage.devices import SlavedDeviceStore
 from synapse.replication.slave.storage.directory import DirectoryStore
 from synapse.replication.slave.storage.events import SlavedEventStore
 from synapse.replication.slave.storage.keys import SlavedKeyStore
+from synapse.replication.slave.storage.profile import SlavedProfileStore
 from synapse.replication.slave.storage.push_rule import SlavedPushRuleStore
 from synapse.replication.slave.storage.receipts import SlavedReceiptsStore
 from synapse.replication.slave.storage.registration import SlavedRegistrationStore
@@ -81,6 +82,7 @@ class ClientReaderSlavedStore(
     SlavedApplicationServiceStore,
     SlavedRegistrationStore,
     SlavedTransactionStore,
+    SlavedProfileStore,
     SlavedClientIpStore,
     BaseSlavedStore,
 ):
diff --git a/synapse/app/frontend_proxy.py b/synapse/app/frontend_proxy.py
index 8479fee738..6504da5278 100644
--- a/synapse/app/frontend_proxy.py
+++ b/synapse/app/frontend_proxy.py
@@ -37,8 +37,7 @@ from synapse.replication.slave.storage.client_ips import SlavedClientIpStore
 from synapse.replication.slave.storage.devices import SlavedDeviceStore
 from synapse.replication.slave.storage.registration import SlavedRegistrationStore
 from synapse.replication.tcp.client import ReplicationClientHandler
-from synapse.rest.client.v1.base import ClientV1RestServlet, client_path_patterns
-from synapse.rest.client.v2_alpha._base import client_v2_patterns
+from synapse.rest.client.v2_alpha._base import client_patterns
 from synapse.server import HomeServer
 from synapse.storage.engines import create_engine
 from synapse.util.httpresourcetree import create_resource_tree
@@ -49,11 +48,11 @@ from synapse.util.versionstring import get_version_string
 logger = logging.getLogger("synapse.app.frontend_proxy")
 
 
-class PresenceStatusStubServlet(ClientV1RestServlet):
-    PATTERNS = client_path_patterns("/presence/(?P<user_id>[^/]*)/status")
+class PresenceStatusStubServlet(RestServlet):
+    PATTERNS = client_patterns("/presence/(?P<user_id>[^/]*)/status")
 
     def __init__(self, hs):
-        super(PresenceStatusStubServlet, self).__init__(hs)
+        super(PresenceStatusStubServlet, self).__init__()
         self.http_client = hs.get_simple_http_client()
         self.auth = hs.get_auth()
         self.main_uri = hs.config.worker_main_http_uri
@@ -84,7 +83,7 @@ class PresenceStatusStubServlet(ClientV1RestServlet):
 
 
 class KeyUploadServlet(RestServlet):
-    PATTERNS = client_v2_patterns("/keys/upload(/(?P<device_id>[^/]+))?$")
+    PATTERNS = client_patterns("/keys/upload(/(?P<device_id>[^/]+))?$")
 
     def __init__(self, hs):
         """
diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index 79be977ea6..1045d28949 100755
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -62,6 +62,7 @@ from synapse.python_dependencies import check_requirements
 from synapse.replication.http import REPLICATION_PREFIX, ReplicationRestResource
 from synapse.replication.tcp.resource import ReplicationStreamProtocolFactory
 from synapse.rest import ClientRestResource
+from synapse.rest.admin import AdminRestResource
 from synapse.rest.key.v2 import KeyApiV2Resource
 from synapse.rest.media.v0.content_repository import ContentRepoResource
 from synapse.rest.well_known import WellKnownResource
@@ -180,6 +181,7 @@ class SynapseHomeServer(HomeServer):
                 "/_matrix/client/v2_alpha": client_resource,
                 "/_matrix/client/versions": client_resource,
                 "/.well-known/matrix/client": WellKnownResource(self),
+                "/_synapse/admin": AdminRestResource(self),
             })
 
             if self.get_config().saml2_enabled: