multicast_dns 0.2.0 not detecting mDNS packets #79772
Description
I'm trying to do a lookup of a specific service using mDNS but the client in Flutter returns nothing albeit the host (Android Device) received the correct packet from mDNS server (see Wireshark section).
Steps to Reproduce
- Create
mDNS server(you can use the following code inGo. So you need to put theGocode in a file calledmain.goand rungo get -u github.com/hashicorp/mdns && go run main.go, please make sure you're running that command in the same folder of yourmain.go. To make sure that the server is running, you can runcurl -X GET 'http://localhost:8081/'and then you should receive anok(see screenshot)
package main
import (
"fmt"
"github.com/hashicorp/mdns"
"os"
"net/http"
)
func health(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "ok")
}
func main() {
hostname, err := os.Hostname()
if err != nil {
panic(fmt.Sprintf("Error getting current hostname, description: %s", err.Error()))
}
info := []string{"mDNS get server"}
service, err := mdns.NewMDNSService(hostname, "_test._tcp", "", "", 8080, nil, info)
if err != nil {
panic(fmt.Sprintf("Error while exporting the service, description: %s", err.Error()))
}
server, err := mdns.NewServer(&mdns.Config{Zone: service})
if err != nil {
panic(fmt.Sprintf("Error while setting the discover server up, description: %s", err.Error()))
}
defer server.Shutdown()
http.HandleFunc("/", health)
http.ListenAndServe(":8081",nil)
}- To check if
mDNS serveris working you can run (OSX):dns-sd -B _test._tcp(Linux:sudo apt-get install avahi-deamonavahi-utils && avahi-browse -rt _test._tcp) - Regarding flutter you can use:
import 'package:multicast_dns/multicast_dns.dart';
import 'dart:io' show Platform;
Future<void> main() async {
const String name = '_test._tcp.local';
MDnsClient client;
if (Platform.isAndroid) {
var factory = (dynamic host, int port,
{bool reuseAddress, bool reusePort, int ttl}) {
print("Hostname $host");
print("Port ${port.toString()}");
return RawDatagramSocket.bind(host, port, reuseAddress: true, reusePort: false, ttl: ttl);
};
client = MDnsClient(rawDatagramSocketFactory: factory);
} else {
client = MDnsClient();
}
// Start the client with default options.
await client.start();
// Get the PTR record for the service.
await for (final PtrResourceRecord ptr in client
.lookup<PtrResourceRecord>(ResourceRecordQuery.serverPointer(name))) {
// Use the domainName from the PTR record to get the SRV record,
// which will have the port and local hostname.
// Note that duplicate messages may come through, especially if any
// other mDNS queries are running elsewhere on the machine.
await for (final SrvResourceRecord srv in client.lookup<SrvResourceRecord>(
ResourceRecordQuery.service(ptr.domainName))) {
// Domain name will be something like "[email protected]._dartobservatory._tcp.local"
final String bundleId =
ptr.domainName; //.substring(0, ptr.domainName.indexOf('@'));
print('Dart observatory instance found at '
'${srv.target}:${srv.port} for "$bundleId".');
}
}
client.stop();
print('Done.');
}- Run
flutter run -d <android-device>.
Expected results:
Something like Dart observatory instance found at...
Actual results:
I/ViewRootImpl(28364): jank_removeInvalidNode all the node in jank list is out of time
W/InputMethodManager(28364): startInputReason = 1
I/flutter (28364): Hostname 0.0.0.0
I/flutter (28364): Port 5353
V/AudioManager(28364): playSoundEffect effectType: 0
V/AudioManager(28364): querySoundEffectsEnabled...
I/flutter (28364): Hostname InternetAddress('127.0.0.1', IPv4)
I/flutter (28364): Port 5353
I/flutter (28364): Hostname InternetAddress('192.168.2.1', IPv4)
I/flutter (28364): Port 5353
I/flutter (28364): Done.Logs
flutter doctor -v
[✓] Flutter (Channel stable, 2.0.4, on Linux, locale en_US.UTF-8)
• Flutter version 2.0.4 at /home/puma/snap/flutter/common/flutter
• Framework revision b1395592de (4 days ago), 2021-04-01 14:25:01 -0700
• Engine revision 2dce47073a
• Dart version 2.12.2
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
• Android SDK at /mnt/hd/Android/android-sdk-linux
• Platform android-30, build-tools 29.0.2
• Java binary at: /snap/android-studio/current/android-studio/jre/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)
• All Android licenses accepted.
[✓] Chrome - develop for the web
• Chrome at google-chrome
[✓] Android Studio
• Android Studio at /snap/android-studio/current/android-studio/
• Flutter plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/6351-dart
• android-studio-dir = /snap/android-studio/current/android-studio/
• Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6222593)
[✓] Connected device (2 available)
• ANE LX1 (mobile) • testAndroid • android-arm64 • Android 9 (API 28)
• Chrome (web) • chrome • web-javascript • Google Chrome 89.0.4389.114
• No issues found!
flutter attach --verbose
[ +148 ms] executing: [/home/puma/snap/flutter/common/flutter/] git -c log.showSignature=false log -n 1 --pretty=format:%H
[ +72 ms] Exit code 0 from: git -c log.showSignature=false log -n 1 --pretty=format:%H
[ ] b1395592de68cc8ac4522094ae59956dd21a91db
[ +1 ms] executing: [/home/puma/snap/flutter/common/flutter/] git tag --points-at b1395592de68cc8ac4522094ae59956dd21a91db
[ +24 ms] Exit code 0 from: git tag --points-at b1395592de68cc8ac4522094ae59956dd21a91db
[ ] 2.0.4
[ +79 ms] executing: [/home/puma/snap/flutter/common/flutter/] git rev-parse --abbrev-ref --symbolic @{u}
[ +8 ms] Exit code 0 from: git rev-parse --abbrev-ref --symbolic @{u}
[ ] origin/stable
[ ] executing: [/home/puma/snap/flutter/common/flutter/] git ls-remote --get-url origin
[ +9 ms] Exit code 0 from: git ls-remote --get-url origin
[ ] https://github.com/flutter/flutter.git
[ +114 ms] executing: [/home/puma/snap/flutter/common/flutter/] git rev-parse --abbrev-ref HEAD
[ +10 ms] Exit code 0 from: git rev-parse --abbrev-ref HEAD
[ ] stable
[ +151 ms] Artifact Instance of 'AndroidGenSnapshotArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'AndroidInternalBuildArtifacts' is not required, skipping update.
[ +3 ms] Artifact Instance of 'IOSEngineArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'FlutterWebSdk' is not required, skipping update.
[ +12 ms] Artifact Instance of 'WindowsEngineArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'MacOSEngineArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'LinuxEngineArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'LinuxFuchsiaSDKArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'MacOSFuchsiaSDKArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'FlutterRunnerSDKArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'FlutterRunnerDebugSymbols' is not required, skipping update.
[ +154 ms] Artifact Instance of 'MaterialFonts' is not required, skipping update.
[ ] Artifact Instance of 'GradleWrapper' is not required, skipping update.
[ ] Artifact Instance of 'AndroidGenSnapshotArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'AndroidInternalBuildArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'IOSEngineArtifacts' is not required, skipping update.
[ +1 ms] Artifact Instance of 'FlutterWebSdk' is not required, skipping update.
[ ] Artifact Instance of 'FlutterSdk' is not required, skipping update.
[ ] Artifact Instance of 'WindowsEngineArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'MacOSEngineArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'LinuxEngineArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'LinuxFuchsiaSDKArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'MacOSFuchsiaSDKArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'FlutterRunnerSDKArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'FlutterRunnerDebugSymbols' is not required, skipping update.
[ ] Artifact Instance of 'IosUsbArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'IosUsbArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'IosUsbArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'IosUsbArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'IosUsbArtifacts' is not required, skipping update.
[ +1 ms] Artifact Instance of 'FontSubsetArtifacts' is not required, skipping update.
[ ] Artifact Instance of 'PubDependencies' is not required, skipping update.
[ +123 ms] executing: /mnt/hd/Android/android-sdk-linux/platform-tools/adb devices -l
[ +68 ms] List of devices attached
testAndroid device usb:2-1.1 product:ANE-LX1 model:ANE_LX1 device:HWANE transport_id:1
[ +102 ms] /mnt/hd/Android/android-sdk-linux/platform-tools/adb -s testAndroid shell getprop
[ +163 ms] Waiting for a connection from Flutter on ANE LX1...
[ +134 ms] Observatory URL on device: http://127.0.0.1:36421/LB5gpdiwoUU=/
[ +2 ms] executing: /mnt/hd/Android/android-sdk-linux/platform-tools/adb -s testAndroid forward tcp:0 tcp:36421
[ +15 ms] 45003
[ +1 ms] Forwarded host port 45003 to device port 36421 for Observatory
[ +9 ms] Connecting to service protocol: http://127.0.0.1:45003/LB5gpdiwoUU=/
[ +186 ms] Launching a Dart Developer Service (DDS) instance at http://127.0.0.1:0, connecting to VM service at http://127.0.0.1:45003/LB5gpdiwoUU=/.
[ +404 ms] Warning: Failed to start DDS: JSON-RPC error 100: Feature is disabled data: {details: A DDS instance is already connected at http://127.0.0.1:32821/rrJgFvQe3xQ=/., request: {jsonrpc: 2.0, method: _yieldControlToDDS, id: 8, params: {uri:
http://127.0.0.1:37321/2bciKM125Ng=/}}}
[ +55 ms] Successfully connected to service protocol: http://127.0.0.1:45003/LB5gpdiwoUU=/
[ +2 ms] executing: /mnt/hd/Android/android-sdk-linux/platform-tools/adb -s testAndroid shell -x logcat -v time -t 1
[ +84 ms] --------- beginning of main
04-05 14:15:50.212 I/TrafficMonitor( 1273): gettimer:interval=2000
[ +955 ms] DevFS: Creating new filesystem on the device (null)
[ +18 ms] DevFS: Creating failed. Destroying and trying again
[ +1 ms] DevFS: Deleting filesystem on the device (null)
[ +34 ms] DevFS: Deleted filesystem on the device (null)
[ +15 ms] DevFS: Created new filesystem on the device (file:///data/user/0/com.example.test_mdns_client/code_cache/test_mdns_clientJAQOEZ/test_mdns_client/)
[ +10 ms] Updating assets
[ +299 ms] Syncing files to device ANE LX1...
[ +4 ms] <- reset
[ ] Compiling dart to kernel with 0 updated files
[ +17 ms] /home/puma/snap/flutter/common/flutter/bin/cache/dart-sdk/bin/dart --disable-dart-dev /home/puma/snap/flutter/common/flutter/bin/cache/artifacts/engine/linux-x64/frontend_server.dart.snapshot --sdk-root
/home/puma/snap/flutter/common/flutter/bin/cache/artifacts/engine/common/flutter_patched_sdk/ --incremental --target=flutter --debugger-module-names --experimental-emit-debug-metadata --output-dill /tmp/flutter_tools.FDFYPD/flutter_tool.JBRCDK/app.dill
--packages /home/puma/StudioProjects/test_mdns_client/.dart_tool/package_config.json -Ddart.vm.profile=false -Ddart.vm.product=false --enable-asserts --track-widget-creation --filesystem-scheme org-dartlang-root --initialize-from-dill
build/cache.dill.track.dill
[ +12 ms] <- compile package:test_mdns_client/main.dart
pubspec.yaml
name: test_mdns_client
description: A new Flutter project.
publish_to: 'none' # Remove this line if you wish to publish to pub.dev
version: 1.0.0+1
environment:
sdk: ">=2.7.0 <3.0.0"
dependencies:
flutter:
sdk: flutter
intl: ^0.15.7
multicast_dns: any
cupertino_icons: ^1.0.2
dev_dependencies:
flutter_test:
sdk: flutter
flutter:
uses-material-design: true
Wireshark
Source Destination Protocol Length Info
192.168.2.1 224.0.0.251 MDNS 76 Standard query 0x0000 PTR _test._tcp.local, "QM" question
192.168.2.4 192.168.2.1 MDNS 180 Standard query response 0x0000 PTR puma._test._tcp.local SRV 10 1 8080 puma A 127.0.1.1 TXT
Where:
192.168.2.1istestAndroiddevice;192.168.2.4is the device where mDNS server is running on.
Thanks in advance for your help!!!