Extend the mDNS package with a native extension used on Mac OS

On Mac OS the mDNSResponder daemon has opened port 5353
exclusively. Therefore it is not possible to speak the mDNS protocol
from Dart using datagram sockets.

The native extension uses the Mac OS DNS Service Discovery C API.

Updated the copyright notice to use Fletch instead of Dart.

BUG= #225
[email protected], [email protected]

Review URL: https://codereview.chromium.org/1407123010 .

Author: sgjesse

.gitignore

@@ -17,6 +17,8 @@ packages
 /fletch.xcodeproj/
 /jniLibs/
 /out/
+/pkg/mdns/lib/native/libmdns_extension_lib.so
+/pkg/mdns/lib/native/libmdns_extension_lib.dylib
 /samples/buildbot/java/
 /samples/github/generated/
 /samples/todomvc/java/

DEPS

@@ -134,6 +134,19 @@ hooks = [
       'fletch/tools/testing/bin',
     ],
   },
+  {
+    'name': 'mdns_native_extension_binaries',
+    'pattern': '.',
+    'action': [
+      'download_from_google_storage',
+      '--no_auth',
+      '--no_resume',
+      '--bucket',
+      'dart-dependencies-fletch',
+      '-d',
+      'fletch/pkg/mdns/lib/native',
+    ],
+  },
   {
     'name': 'third_party_qemu',
     'pattern': '.',

build.ninja

@@ -65,6 +65,7 @@ build $
         src/shared/shared.gyp $
         src/tools/driver/driver.gyp $
         src/vm/vm.gyp $
+        src/pkg/mdns/mdns.gyp $
 
 build gyp: phony$
     out/DebugIA32/build.ninja $

fletch.gyp

@@ -18,6 +18,13 @@
         'src/vm/vm.gyp:ffi_test_library',
       ],
     },
+    {
+      'target_name': 'mdns_extension_lib',
+      'type': 'none',
+      'dependencies': [
+        'src/pkg/mdns/mdns.gyp:mdns_extension_lib',
+      ],
+    },
     {
       'target_name': 'natives_json',
       'type': 'none',

pkg/mdns/lib/mdns.dart

@@ -1,68 +1,48 @@
-// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2015, the Fletch project authors. Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
+// BSD-style license that can be found in the LICENSE.md file.
+
+library mdns;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:io';
 import 'dart:typed_data';
 
-import 'package:mdns/src/constants.dart';
-import 'package:mdns/src/lookup_resolver.dart';
-import 'package:mdns/src/packet.dart';
+import 'package:mdns/src/native_extension_client.dart';
+import 'package:mdns/src/native_protocol_client.dart';
 
 /// Client for DNS lookup using the mDNS protocol.
 ///
 /// This client only support "One-Shot Multicast DNS Queries" as described in
 /// section 5.1 of https://tools.ietf.org/html/rfc6762
-class MDnsClient {
-  bool _starting = false;
-  bool _started = false;
-  RawDatagramSocket _incoming;
-  final List<RawDatagramSocket> _sockets = <RawDatagramSocket>[];
-  final LookupResolver _resolver = new LookupResolver();
-
-  /// Start the mDNS client.
-  Future start() async {
-    if (_started && _starting) {
-      throw new StateError('mDNS client already started');
-    }
-    _starting = true;
-
-    // Listen on all addresses.
-    _incoming = await RawDatagramSocket.bind(
-        InternetAddress.ANY_IP_V4, mDnsPort, reuseAddress: true);
-
-    // Find all network interfaces with an IPv4 address.
-    var interfaces =
-        await NetworkInterface.list(type: InternetAddressType.IP_V4);
-    for (NetworkInterface interface in interfaces) {
-      // Create a socket for sending on each adapter.
-      var socket = await RawDatagramSocket.bind(
-          interface.addresses[0], mDnsPort, reuseAddress: true);
-      _sockets.add(socket);
-
-      // Join multicast on this interface.
-      _incoming.joinMulticast(mDnsAddress, interface);
+abstract class MDnsClient {
+  // Instantiate Client for DNS lookup using the mDNS protocol.
+  //
+  // On Mac OS a native extension is used as the mDNSResponder opens the mDNS
+  // port in exclusive mode. To test the protocol implementation on Mac OS
+  // one can turn off mDNSResponder:
+  //
+  // sudo launchctl unload -w \
+  //     /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
+  //
+  // And turn it on again:
+  //
+  // sudo launchctl load -w \
+  //    /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
+  factory MDnsClient() {
+    if (Platform.isMacOS) {
+      return new NativeExtensionMDnsClient();
+    } else {
+      return new NativeProtocolMDnsClient();
     }
-    _incoming.listen(_handleIncoming);
-
-    _starting = false;
-    _started = true;
   }
 
-  /// Stop the mDNS client.
-  void stop() {
-    if (!_started) return;
-    if (_starting) {
-      throw new StateError('Cannot stop mDNS client wile it is starting');
-    }
-
-    _sockets.forEach((socket) => socket.close());
-    _incoming.close();
+  /// Start the mDNS client.
+  Future start();
 
-    _started = false;
-  }
+  /// Stop the mDNS client.
+  void stop();
 
   /// Lookup [hostname] using mDNS.
   ///
@@ -72,40 +52,14 @@ class MDnsClient {
   /// If no answer has been received within the specified [timeout]
   /// this method will complete with the value `null`.
   Future<InternetAddress> lookup(
-      String hostname, {Duration timeout: const Duration(seconds: 5)}) {
-    if (!_started) {
-      throw new StateError('mDNS client is not started');
-    }
-
-    // Add the pending request before sending the query.
-    var future = _resolver.addPendingRequest(hostname, timeout);
-
-    // Send the request on all interfaces.
-    List<int> packet = encodeMDnsQuery(hostname);
-    for (int i = 0; i < _sockets.length; i++) {
-      _sockets[i].send(packet, mDnsAddress, mDnsPort);
-    }
-
-    return future;
-  }
-
-  // Process incoming datagrams.
-  _handleIncoming(event) {
-    if (event == RawSocketEvent.READ) {
-      var data = _incoming.receive();
-      var response = decodeMDnsResponse(data.data);
-      if (response != null) {
-        _resolver.handleResponse(response);
-      }
-    }
-  }
+      String hostname, {Duration timeout: const Duration(seconds: 5)});
 }
 
 // Simple standalone test.
-main() async {
+Future main(List<String> args) async {
   var client = new MDnsClient();
   await client.start();
-  var address = await client.lookup('raspberrypi.local');
+  var address = await client.lookup(args[0]);
   client.stop();
   print(address);
 }

pkg/mdns/lib/native/libmdns_extension_lib.dylib.sha1

@@ -0,0 +1 @@
+22e12795d48159983c756e96b4355ca63b020676

pkg/mdns/lib/native/libmdns_extension_lib.so.sha1

@@ -0,0 +1 @@
+a1bcfd86ed70bf854de519d29cf354871459d825

pkg/mdns/lib/src/constants.dart

@@ -1,6 +1,6 @@
-// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2015, the Fletch project authors. Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
+// BSD-style license that can be found in the LICENSE.md file.
 
 library mdns.src.constants;
 

pkg/mdns/lib/src/lookup_resolver.dart

@@ -1,6 +1,6 @@
-// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2015, the Fletch project authors. Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
+// BSD-style license that can be found in the LICENSE.md file.
 
 library mdns.src.lookup_resolver;
 
@@ -34,13 +34,16 @@ class LookupResolver {
 
   void handleResponse(List<DecodeResult> response) {
     for (var r in response) {
+      var name = r.name.toLowerCase();
+      if (name.endsWith('.')) name = name.substring(0, name.length - 1);
       pendingRequests
-          .where((pendingRequest) => pendingRequest.hostname == r.name)
+          .where((pendingRequest) {
+            return pendingRequest.hostname.toLowerCase() == name;
+          })
           .forEach((pendingRequest) {
                 pendingRequest.completer.complete(r.address);
                 pendingRequest.unlink();
-              });
-          }
+          });
+    }
   }
 }
-

pkg/mdns/lib/src/native_extension_client.dart

@@ -0,0 +1,106 @@
+// Copyright (c) 2015, the Fletch project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE.md file.
+
+library mdns.src.native_extension_client;
+
+import 'dart:async';
+import 'dart:io';
+import 'dart:isolate';
+
+import 'package:mdns/mdns.dart';
+import 'package:mdns/src/lookup_resolver.dart';
+import 'package:mdns/src/packet.dart';
+
+import "dart-ext:../native/mdns_extension_lib";
+
+// Requests Ids. This should be aligned with the C code.
+enum RequestType {
+  echoRequest,  // 0
+  lookupRequest,  // 1
+}
+
+// Implementation of mDNS client using a native extension.
+class NativeExtensionMDnsClient implements MDnsClient {
+  bool _starting = false;
+  bool _started = false;
+  SendPort _service;
+  ReceivePort _incoming;
+  final LookupResolver _resolver = new LookupResolver();
+
+  /// Start the mDNS client.
+  Future start() async {
+    if (_started && _starting) {
+      throw new StateError('mDNS client already started');
+    }
+    _starting = true;
+
+    _service = servicePort();
+    _incoming = new ReceivePort();
+    _incoming.listen(_handleIncoming);
+
+    _starting = false;
+    _started = true;
+  }
+
+  void stop() {
+    if (!_started) return;
+    if (_starting) {
+      throw new StateError('Cannot stop mDNS client wile it is starting');
+    }
+
+    _incoming.close();
+
+    _started = false;
+  }
+
+  Future<InternetAddress> lookup(
+      String hostname, {Duration timeout: const Duration(seconds: 5)}) {
+    if (!_started) {
+      throw new StateError('mDNS client is not started');
+    }
+
+    // Add the pending request before sending the query.
+    var future = _resolver.addPendingRequest(hostname, timeout);
+
+    // Send the request.
+    _service.send([_incoming.sendPort,
+                   RequestType.lookupRequest.index,
+                   hostname]);
+
+    return future;
+  }
+
+  // Process incoming responses.
+  _handleIncoming(response) {
+    // Right not the only response we can get is the response to a
+    // lookupRequest where the response looks like this:
+    //
+    //  response[0]: hostname (String)
+    //  response[1]: IPv4 address (Uint8List)
+    if (response is List && response.length == 2) {
+      if (response[0] is String &&
+          response[1] is List && response[1].length == 4) {
+        response = new DecodeResult(response[0],
+                                    new InternetAddress(response[1].join('.')));
+        _resolver.handleResponse([response]);
+      } else {
+        // TODO(sgjesse): Improve the error handling.
+        print('mDNS Response not understood');
+      }
+    }
+  }
+}
+
+Future nativeExtensionEchoTest(dynamic message) async {
+  SendPort service = servicePort();
+  ReceivePort port = new ReceivePort();
+  try {
+    service.send([port.sendPort, RequestType.echoRequest.index, message]);
+    return await port.first;
+  } finally {
+    port.close();
+  }
+}
+
+SendPort servicePort() native 'MDnsExtension_ServicePort';