Initial refactor/adding of mdns

Author: dnfield

.gitignore

@@ -3,6 +3,8 @@
 .idea
 .packages
 .pub/
+.dart_tool/
+
 pubspec.lock
 
 Podfile.lock

packages/multicast_dns/CHANGELOG.md

@@ -0,0 +1,5 @@
+## 0.1.0
+
+* Initial Open Source release.
+* Migrates the dartino-sdk's mDNS client to Dart 2.0 and Flutter's analysis rules
+* Breaks from original Dartino code, as it does not use native libraries for macOS and overhauls the `ResourceRecord` class.

packages/multicast_dns/LICENSE

@@ -0,0 +1,27 @@
+Copyright 2014 The Chromium Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+    * Neither the name of Google Inc. nor the names of its
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

pkg/mdns/bin/mdns-resolve.dart renamed to packages/multicast_dns/example/mdns-resolve.dart

@@ -1,19 +1,19 @@
 // Copyright (c) 2015, the Dartino 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.
+// BSD-style license that can be found in the LICENSE file.
 
 // Example script to illustrate how to use the mdns package to lookup names
 // on the local network.
 
 import 'package:args/args.dart';
 
-import '../lib/mdns.dart';
+import 'package:multicast_dns/mdns_client.dart';
 
-main(List<String> args) async {
+void main(List<String> args) async {
   // Parse the command line arguments.
-  var parser = new ArgParser();
+  final ArgParser parser = ArgParser();
   parser.addOption('timeout', abbr: 't', defaultsTo: '5');
-  var arguments = parser.parse(args);
+  final ArgResults arguments = parser.parse(args);
 
   if (arguments.rest.length != 1) {
     print('''
@@ -24,14 +24,13 @@ For example:
     return;
   }
 
-  var name = arguments.rest[0];
+  final String name = arguments.rest[0];
 
-  MDnsClient client = new MDnsClient();
+  final MDnsClient client = MDnsClient();
   await client.start();
-  var timeout;
-  timeout = new Duration(seconds: int.parse(arguments['timeout']));
-  await for (ResourceRecord record in
-             client.lookup(RRType.A, name, timeout: timeout)) {
+  final Duration timeout = Duration(seconds: int.parse(arguments['timeout']));
+  await for (IPAddressResourceRecord record
+      in client.lookup(RRType.a, name, timeout: timeout)) {
     print('Found address (${record.address}).');
   }
   client.stop();

packages/multicast_dns/example/mdns-sd.dart

@@ -0,0 +1,46 @@
+// Copyright (c) 2015, the Dartino 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.
+
+// Example script to illustrate how to use the mdns package to discover services
+// on the local network.
+
+import 'package:args/args.dart';
+
+import 'package:multicast_dns/mdns_client.dart';
+
+void main(List<String> args) async {
+  // Parse the command line arguments.
+  final ArgParser parser = ArgParser();
+  parser.addOption('timeout', abbr: 't', defaultsTo: '5');
+  final ArgResults arguments = parser.parse(args);
+
+  if (arguments.rest.length != 1) {
+    print('''
+Please provide the name of a service as argument.
+
+For example:
+  dart mdns-sd.dart  [--timeout <timeout>] _workstation._tcp.local''');
+    return;
+  }
+
+  final String name = arguments.rest[0];
+
+  final MDnsClient client = MDnsClient();
+  await client.start();
+  await for (PtrResourceRecord ptr in client.lookup(RRType.ptr, name)) {
+    final String domain = ptr.domainName;
+    print(ptr);
+    await for (SrvResourceRecord srv in client.lookup(RRType.srv, domain)) {
+      final String target = srv.target;
+      print(srv);
+      await client.lookup(RRType.txt, domain).forEach(print);
+      await for (IPAddressResourceRecord ip
+          in client.lookup(RRType.a, target)) {
+        print(ip);
+        print('Service instance found at $target (${ip.address}).');
+      }
+    }
+  }
+  client.stop();
+}

packages/multicast_dns/lib/mdns_client.dart

@@ -0,0 +1,132 @@
+// ignore_for_file: undefined_named_parameter
+// Copyright (c) 2015, the Dartino 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.
+
+import 'dart:async';
+import 'dart:io';
+
+import 'package:multicast_dns/src/constants.dart';
+import 'package:multicast_dns/src/lookup_resolver.dart';
+import 'package:multicast_dns/src/native_protocol_client.dart';
+import 'package:multicast_dns/src/packet.dart';
+import 'package:multicast_dns/src/resource_record.dart';
+
+export 'package:multicast_dns/src/resource_record.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 = LookupResolver();
+  final ResourceRecordCache _cache = ResourceRecordCache();
+
+  /// Start the mDNS client.
+  Future<void> start() async {
+    if (_started && _starting) {
+      throw StateError('mDNS client already started');
+    }
+    _starting = true;
+
+    // Listen on all addresses.
+    _incoming = await RawDatagramSocket.bind(
+      InternetAddress.anyIPv4,
+      mDnsPort,
+      reuseAddress: true,
+      reusePort: true,
+      ttl: 255,
+    );
+    // Find all network interfaces with an IPv4 address.
+    final List<NetworkInterface> interfaces = await NetworkInterface.list(
+      includeLinkLocal: true,
+      type: InternetAddressType.IPv4,
+      includeLoopback: true,
+    );
+
+    _sockets.add(_incoming);
+
+    for (NetworkInterface interface in interfaces) {
+      // Create a socket for sending on each adapter.
+      final RawDatagramSocket socket = await RawDatagramSocket.bind(
+        interface.addresses[0],
+        mDnsPort,
+        reuseAddress: true,
+        reusePort: true,
+        ttl: 255,
+      );
+      _sockets.add(socket);
+
+      // Join multicast on this interface.
+      _incoming.joinMulticast(mDnsAddress, interface);
+    }
+    _incoming.listen(_handleIncoming);
+
+    _starting = false;
+    _started = true;
+  }
+
+  /// Stop the client and close any associated sockets.
+  void stop() {
+    if (!_started) {
+      return;
+    }
+    if (_starting) {
+      throw StateError('Cannot stop mDNS client wile it is starting');
+    }
+
+    for (RawDatagramSocket socket in _sockets) {
+      socket.close();
+    }
+
+    _resolver.clearPendingRequests();
+
+    _started = false;
+  }
+
+  /// Lookup a [ResourceRecord], potentially from cache.
+  Stream<ResourceRecord> lookup(int type, String name,
+      {Duration timeout = const Duration(seconds: 5)}) {
+    if (!_started) {
+      throw StateError('mDNS client is not started');
+    }
+    // Look for entries in the cache.
+    final List<ResourceRecord> cached = <ResourceRecord>[];
+    _cache.lookup(name, type, cached);
+    if (cached.isNotEmpty) {
+      final StreamController<ResourceRecord> controller =
+          StreamController<ResourceRecord>();
+      cached.forEach(controller.add);
+      controller.close();
+      return controller.stream;
+    }
+
+    // Add the pending request before sending the query.
+    final Stream<ResourceRecord> results =
+        _resolver.addPendingRequest(type, name, timeout);
+
+    // Send the request on all interfaces.
+    final List<int> packet = encodeMDnsQuery(name, type: type);
+    for (RawDatagramSocket socket in _sockets) {
+      socket.send(packet, mDnsAddress, mDnsPort);
+    }
+    return results;
+  }
+
+  // Process incoming datagrams.
+  void _handleIncoming(RawSocketEvent event) {
+    if (event == RawSocketEvent.read) {
+      final Datagram datagram = _incoming.receive();
+
+      final List<ResourceRecord> response = decodeMDnsResponse(datagram.data);
+      if (response != null) {
+        _cache.updateRecords(response);
+        _resolver.handleResponse(response);
+      }
+    }
+  }
+}

packages/multicast_dns/lib/multicast_dns.dart

@@ -0,0 +1,3 @@
+export 'package:multicast_dns/src/resource_record.dart';
+
+export 'mdns_client.dart';

packages/multicast_dns/lib/src/constants.dart

@@ -0,0 +1,26 @@
+// Copyright (c) 2015, the Dartino 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.
+
+import 'dart:io';
+
+/// The IPv4 mDNS Address.
+InternetAddress mDnsAddress = InternetAddress('224.0.0.251');
+
+/// The mDNS port.
+const int mDnsPort = 5353;
+
+/// Enumeration of supported resource record class types.
+class RRClass {
+  /// Internet address class ("IN").
+  static const int internet = 1;
+}
+
+/// Enumeration of DNS question types.
+class QuestionType {
+  /// "QU" Question.
+  static const int unicast = 0x8000;
+
+  /// "QM" Question.
+  static const int multicast = 0x0000;
+}

packages/multicast_dns/lib/src/lookup_resolver.dart

@@ -0,0 +1,83 @@
+// Copyright (c) 2015, the Dartino 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.
+
+import 'dart:async';
+import 'dart:collection';
+
+import 'package:multicast_dns/src/resource_record.dart';
+
+/// Class for maintaining state about pending mDNS requests.
+class PendingRequest extends LinkedListEntry<PendingRequest> {
+  /// Creates a new PendingRequest.
+  PendingRequest(this.type, this.name, this.controller);
+
+  /// The [RRType] of the request.
+  final int type;
+
+  /// The domain name.
+  final String name;
+
+  /// A StreamController managing the request.
+  final StreamController<ResourceRecord> controller;
+
+  /// The timer for the request.
+  Timer timer;
+}
+
+/// Class for keeping track of pending lookups and process incoming
+/// query responses.
+class LookupResolver {
+  /// The requests the process.
+  final LinkedList<PendingRequest> pendingRequests =
+      LinkedList<PendingRequest>();
+
+  /// Adds a request and returns a [Stream] of [ResourceRecord] responses.
+  Stream<ResourceRecord> addPendingRequest(
+      int type, String name, Duration timeout) {
+    final StreamController<ResourceRecord> controller =
+        StreamController<ResourceRecord>();
+    final PendingRequest request = PendingRequest(type, name, controller);
+    final Timer timer = Timer(timeout, () {
+      request.unlink();
+      controller.close();
+    });
+    request.timer = timer;
+    pendingRequests.add(request);
+    return controller.stream;
+  }
+
+  /// Processes responses back to the caller.
+  void handleResponse(List<ResourceRecord> response) {
+    for (ResourceRecord r in response) {
+      final int type = r.rrValue;
+      String name = r.name.toLowerCase();
+      if (name.endsWith('.')) {
+        name = name.substring(0, name.length - 1);
+      }
+
+      bool responseMatches(PendingRequest request) {
+        return request.name.toLowerCase() == name && request.type == type;
+      }
+
+      for (PendingRequest pendingRequest in pendingRequests) {
+        if (responseMatches(pendingRequest)) {
+          if (pendingRequest.controller.isClosed) {
+            return;
+          }
+          pendingRequest.controller.add(r);
+        }
+      }
+    }
+  }
+
+  /// Removes any pending requests and ends processing.
+  void clearPendingRequests() {
+    while (pendingRequests.isNotEmpty) {
+      final PendingRequest request = pendingRequests.first;
+      request.unlink();
+      request.timer.cancel();
+      request.controller.close();
+    }
+  }
+}