Not able to connect to nodeJS server on localHost

[LucasMorais10]

Hi, i'm trying to stabilish a connection between a nodeJS server and a flutter app but I always receive connect_error on client side. If I try to connect by the browser, it's successful, so i think the problem is on client side.

My nodeJS server:

const app = require('express')()
const http = require('http').createServer(app)
var io = require('socket.io')(http)

io.on('connection', (client) => {  
    console.log('a user connected')

    client.on('message', (data) => {
        console.log('Message received --> ', data)

        // io.emit('chat', data)
    })
})

http.listen(5000, () => {  
    console.log('Listening on port 5000')
})

Client side is implemented on InitState as follows:

@override
  void initState() {
    //on xxx.xxx.xxx.xxx i'm inserting my local ip address
    socket = IO.io('http//xxx.xxx.xxx.xxx:5000/', <String, dynamic>{
      'transports': ['websocket']
    });

    socket.connect();
    socket.on("connect", (_) => print('Connected'));
    socket.on("connect_error", (data) => print('connect_error: ' + data));
    
    super.initState();
  }

The client keeps showing the output "connect_error: timeout".

Anybody can help? Thanks in advance.

[jumperchen]

Which version are you using? (both client and server)

[jumperchen]

@LucasMorais10 I try with your example in my env. with Android simulator and it works well.
Here is my env. version:

• NodeJs Socket.io server: 2.3.0
• Flutter 1.12.13+hotfix.7
• Dart 2.7.0
• socket_io_client 0.9.8

[LucasMorais10]

Hi @jumperchen, thanks for the answer. Here are the versions for my env:

• NodeJs Socket.io server: 2.3.0
• Flutter 1.12.13+hotfix.8
• Dart 2.7.0
• socket_io_client 0.9.4

I updated socket_io_client to 0.9.8 and still getting the same error. Do you think it could be something wrong on my network?

[jumperchen]

@LucasMorais10 Did you use it in your Android Studio? or in a real mobile device?
If it's in Android Studio, the simulator is a VM which should be able to access your server if possible.

[LucasMorais10]

It is a real android device.

Both pc and android device are connected to the same router.

I also tried to disable all firewall on server side, but didn't help anyway.

I can ping between them and access the server on the Android web browser. I don't see why i can't connect with the flutter client :/

[theguywithideas]

Any Update on this? Getting the same problem

[jumperchen]

@theguywithideas can you provide an example to demonstrate the issue you met?

[aakashpothepalli]

IO.Socket socket = IO.io('http://localhost:3000', <String, dynamic>{
    'transports': ['websocket'],
    'extraHeaders': {'foo': 'bar'} // optional
  });

make sure you add this

[theguywithideas]

@jumperchen @aakash9518 I was able to find the problem in my code and correct it. Thanks for the prompt replies though.

[aquibbaig]

@theguywithideas What was the issue cause I'm having the same problem?

[theguywithideas]

@aquibbaig the problem that I faced was because of the way this package is accepting the endpoint of socket.io. In my case it was https://subdomain.domain.com/socketio initially and the connection to that endpoint was getting rejected. I later found out that the library expects the url in the format https://subdomain.domain.com only. The /socketio part after that is being considered as a namespace and that's why my connection was getting established. I just changed my socketio server domain to https://someothersubdomain.domain.com and got rid of /socketio part and it got connected to the default namespace. Not sure if you are facing the same problem or not. I think they should mention this in docs.

[aquibbaig]

Thanks for your quick update. I was actually facing a CORS issue!

[lehno]

Im having this problem, but my localserver is https. The error is:
CERTIFICATE_VERIFY_FAILED: unable to get local issuer certificate.

Any tips on how to use it with self signed cert?

[jumperchen]

FYI: dart-lang/sdk#34284
Not sure whether it's related or not.