Implement mdns for flutter run (flutter#40447)

Author: christopherfujino

packages/flutter_tools/lib/src/commands/attach.dart

@@ -4,8 +4,6 @@
 
 import 'dart:async';
 
-import 'package:multicast_dns/multicast_dns.dart';
-
 import '../artifacts.dart';
 import '../base/common.dart';
 import '../base/context.dart';
@@ -21,6 +19,7 @@ import '../fuchsia/fuchsia_device.dart';
 import '../globals.dart';
 import '../ios/devices.dart';
 import '../ios/simulators.dart';
+import '../mdns_discovery.dart';
 import '../project.dart';
 import '../protocol_discovery.dart';
 import '../resident_runner.dart';
@@ -207,7 +206,7 @@ class AttachCommand extends FlutterCommand {
     final String hostname = usesIpv6 ? ipv6Loopback : ipv4Loopback;
 
     bool attachLogger = false;
-    if (devicePort == null  && debugUri == null) {
+    if (devicePort == null && debugUri == null) {
       if (device is FuchsiaDevice) {
         attachLogger = true;
         final String module = argResults['module'];
@@ -229,10 +228,11 @@ class AttachCommand extends FlutterCommand {
           rethrow;
         }
       } else if ((device is IOSDevice) || (device is IOSSimulator)) {
-        final MDnsObservatoryDiscoveryResult result = await MDnsObservatoryDiscovery().query(applicationId: appId);
-        if (result != null) {
-          observatoryUri = await _buildObservatoryUri(device, hostname, result.port, result.authCode);
-        }
+        observatoryUri = await MDnsObservatoryDiscovery.instance.getObservatoryUri(
+          appId,
+          device,
+          usesIpv6,
+        );
       }
       // If MDNS discovery fails or we're not on iOS, fallback to ProtocolDiscovery.
       if (observatoryUri == null) {
@@ -254,8 +254,13 @@ class AttachCommand extends FlutterCommand {
         }
       }
     } else {
-      observatoryUri = await _buildObservatoryUri(device,
-          debugUri?.host ?? hostname, devicePort ?? debugUri.port, debugUri?.path);
+      observatoryUri = await buildObservatoryUri(
+        device,
+        debugUri?.host ?? hostname,
+        devicePort ?? debugUri.port,
+        observatoryPort,
+        debugUri?.path,
+      );
     }
     try {
       final bool useHot = getBuildInfo().isDebug;
@@ -337,22 +342,6 @@ class AttachCommand extends FlutterCommand {
   }
 
   Future<void> _validateArguments() async { }
-
-  Future<Uri> _buildObservatoryUri(Device device,
-      String host, int devicePort, [String authCode]) async {
-    String path = '/';
-    if (authCode != null) {
-      path = authCode;
-    }
-    // Not having a trailing slash can cause problems in some situations.
-    // Ensure that there's one present.
-    if (!path.endsWith('/')) {
-      path += '/';
-    }
-    final int localPort = observatoryPort
-        ?? await device.portForwarder.forward(devicePort);
-    return Uri(scheme: 'http', host: host, port: localPort, path: path);
-  }
 }
 
 class HotRunnerFactory {
@@ -383,132 +372,3 @@ class HotRunnerFactory {
     ipv6: ipv6,
   );
 }
-
-class MDnsObservatoryDiscoveryResult {
-  MDnsObservatoryDiscoveryResult(this.port, this.authCode);
-  final int port;
-  final String authCode;
-}
-
-/// A wrapper around [MDnsClient] to find a Dart observatory instance.
-class MDnsObservatoryDiscovery {
-  /// Creates a new [MDnsObservatoryDiscovery] object.
-  ///
-  /// The [client] parameter will be defaulted to a new [MDnsClient] if null.
-  /// The [applicationId] parameter may be null, and can be used to
-  /// automatically select which application to use if multiple are advertising
-  /// Dart observatory ports.
-  MDnsObservatoryDiscovery({MDnsClient mdnsClient})
-    : client = mdnsClient ?? MDnsClient();
-
-  /// The [MDnsClient] used to do a lookup.
-  final MDnsClient client;
-
-  static const String dartObservatoryName = '_dartobservatory._tcp.local';
-
-  /// Executes an mDNS query for a Dart Observatory.
-  ///
-  /// The [applicationId] parameter may be used to specify which application
-  /// to find.  For Android, it refers to the package name; on iOS, it refers to
-  /// the bundle ID.
-  ///
-  /// If it is not null, this method will find the port and authentication code
-  /// of the Dart Observatory for that application. If it cannot find a Dart
-  /// Observatory matching that application identifier, it will call
-  /// [throwToolExit].
-  ///
-  /// If it is null and there are multiple ports available, the user will be
-  /// prompted with a list of available observatory ports and asked to select
-  /// one.
-  ///
-  /// If it is null and there is only one available instance of Observatory,
-  /// it will return that instance's information regardless of what application
-  /// the Observatory instance is for.
-  Future<MDnsObservatoryDiscoveryResult> query({String applicationId}) async {
-    printStatus('Checking for advertised Dart observatories...');
-    try {
-      await client.start();
-      final List<PtrResourceRecord> pointerRecords = await client
-          .lookup<PtrResourceRecord>(
-            ResourceRecordQuery.serverPointer(dartObservatoryName),
-          )
-          .toList();
-      if (pointerRecords.isEmpty) {
-        return null;
-      }
-      // We have no guarantee that we won't get multiple hits from the same
-      // service on this.
-      final List<String> uniqueDomainNames = pointerRecords
-          .map<String>((PtrResourceRecord record) => record.domainName)
-          .toSet()
-          .toList();
-
-      String domainName;
-      if (applicationId != null) {
-        for (String name in uniqueDomainNames) {
-          if (name.toLowerCase().startsWith(applicationId.toLowerCase())) {
-            domainName = name;
-            break;
-          }
-        }
-        if (domainName == null) {
-          throwToolExit('Did not find a observatory port advertised for $applicationId.');
-        }
-      } else if (uniqueDomainNames.length > 1) {
-        final StringBuffer buffer = StringBuffer();
-        buffer.writeln('There are multiple observatory ports available.');
-        buffer.writeln('Rerun this command with one of the following passed in as the appId:');
-        buffer.writeln('');
-         for (final String uniqueDomainName in uniqueDomainNames) {
-          buffer.writeln('  flutter attach --app-id ${uniqueDomainName.replaceAll('.$dartObservatoryName', '')}');
-        }
-        throwToolExit(buffer.toString());
-      } else {
-        domainName = pointerRecords[0].domainName;
-      }
-      printStatus('Checking for available port on $domainName');
-      // Here, if we get more than one, it should just be a duplicate.
-      final List<SrvResourceRecord> srv = await client
-          .lookup<SrvResourceRecord>(
-            ResourceRecordQuery.service(domainName),
-          )
-          .toList();
-      if (srv.isEmpty) {
-        return null;
-      }
-      if (srv.length > 1) {
-        printError('Unexpectedly found more than one observatory report for $domainName '
-                   '- using first one (${srv.first.port}).');
-      }
-      printStatus('Checking for authentication code for $domainName');
-      final List<TxtResourceRecord> txt = await client
-        .lookup<TxtResourceRecord>(
-            ResourceRecordQuery.text(domainName),
-        )
-        ?.toList();
-      if (txt == null || txt.isEmpty) {
-        return MDnsObservatoryDiscoveryResult(srv.first.port, '');
-      }
-      String authCode = '';
-      const String authCodePrefix = 'authCode=';
-      String raw = txt.first.text;
-      // TXT has a format of [<length byte>, text], so if the length is 2,
-      // that means that TXT is empty.
-      if (raw.length > 2) {
-        // Remove length byte from raw txt.
-        raw = raw.substring(1);
-        if (raw.startsWith(authCodePrefix)) {
-          authCode = raw.substring(authCodePrefix.length);
-          // The Observatory currently expects a trailing '/' as part of the
-          // URI, otherwise an invalid authentication code response is given.
-          if (!authCode.endsWith('/')) {
-            authCode += '/';
-          }
-        }
-      }
-      return MDnsObservatoryDiscoveryResult(srv.first.port, authCode);
-    } finally {
-      client.stop();
-    }
-  }
-}

packages/flutter_tools/lib/src/context_runner.dart

@@ -45,6 +45,7 @@ import 'macos/cocoapods_validator.dart';
 import 'macos/macos_workflow.dart';
 import 'macos/xcode.dart';
 import 'macos/xcode_validator.dart';
+import 'mdns_discovery.dart';
 import 'reporting/reporting.dart';
 import 'run_hot.dart';
 import 'version.dart';
@@ -101,6 +102,7 @@ Future<T> runInContext<T>(
       LinuxWorkflow: () => const LinuxWorkflow(),
       Logger: () => platform.isWindows ? WindowsStdoutLogger() : StdoutLogger(),
       MacOSWorkflow: () => const MacOSWorkflow(),
+      MDnsObservatoryDiscovery: () => MDnsObservatoryDiscovery(),
       OperatingSystemUtils: () => OperatingSystemUtils(),
       ProcessUtils: () => ProcessUtils(),
       SimControl: () => SimControl(),

packages/flutter_tools/lib/src/ios/devices.dart

@@ -19,6 +19,7 @@ import '../build_info.dart';
 import '../convert.dart';
 import '../device.dart';
 import '../globals.dart';
+import '../mdns_discovery.dart';
 import '../project.dart';
 import '../protocol_discovery.dart';
 import '../reporting/reporting.dart';
@@ -345,7 +346,6 @@ class IOSDevice extends Device {
           ipv6: ipv6,
         );
       }
-
       final int installationResult = await IOSDeploy.instance.runApp(
         deviceId: id,
         bundlePath: bundle.path,
@@ -363,16 +363,36 @@ class IOSDevice extends Device {
         return LaunchResult.succeeded();
       }
 
+      Uri localUri;
       try {
         printTrace('Application launched on the device. Waiting for observatory port.');
-        final Uri localUri = await observatoryDiscovery.uri;
-        return LaunchResult.succeeded(observatoryUri: localUri);
+        localUri = await MDnsObservatoryDiscovery.instance.getObservatoryUri(
+          package.id,
+          this,
+          ipv6,
+          debuggingOptions.observatoryPort,
+        );
+        if (localUri != null) {
+          return LaunchResult.succeeded(observatoryUri: localUri);
+        }
+      } catch (error) {
+        printError('Failed to establish a debug connection with $id: $error');
+      }
+
+      // Fallback to manual protocol discovery
+      printTrace('mDNS lookup failed, attempting fallback to reading device log.');
+      try {
+        printTrace('Waiting for observatory port.');
+        localUri = await observatoryDiscovery.uri;
+        if (localUri != null) {
+          return LaunchResult.succeeded(observatoryUri: localUri);
+        }
       } catch (error) {
         printError('Failed to establish a debug connection with $id: $error');
-        return LaunchResult.failed();
       } finally {
         await observatoryDiscovery?.cancel();
       }
+      return LaunchResult.failed();
     } finally {
       installStatus.stop();
     }