CODEWITHSUNDEEP
javaandroidsocketswifihotspot
Maldus
Maldus

Reputation: 11797

Android socket connection between hotspot and client

I am making an app that checks for certain connections (looking for a list of SSIDs) and creates an hotspot for said connection if it doesn't find any. Basically it should act as a local area network. I am successful in creating the hotspot, and after that it listens on a server socket for incoming connections:

Thread socketThread = new Thread(new Runnable() {
        @Override
        public void run() {
            int port = Constants.PORT + socketList.size()-1;
            try {
                ServerSocket serverSocket = null;
                serverSocket = new ServerSocket(port);
                Log.d(TAG, "Socket listening for connections: " + port);
                Socket client = serverSocket.accept();
                Log.d(TAG, "Server: connection done");
                InputStream inputstream = client.getInputStream();
                DataInputStream commStream = new DataInputStream(inputstream);
                byte[] b = new byte[16];
                while (commStream.read(b,0, 16) != -1)
                    Log.d(TAG, new String(b, "ASCII"));
                serverSocket.close();
                Log.d(TAG, "Server socket done");
            } catch (Exception e) {
                Log.e(TAG, e.toString());
            }
        }

    });
    socketList.add(socketThread);
    socketThread.start();

If I create the hotspot and connect to it with my pc I am able to use netcat and connect with said socket:

netcat 192.168.43.1 8988

Where 192.168.43.1 is the default Android IP address for the hotspot and 8988 is the port I'm using. However, when I try to do the same through another device running the app and connecting to the hotspot, it doesn't work. Here's the client code:

clientThread = new Thread(new Runnable() {
        @Override
        public void run() {
            int port = Constants.PORT ;
            try {
                Socket socket =new Socket();
                socket.bind(null);
                socket.connect((new InetSocketAddress("192.168.43.1", port)), 20000);
                OutputStream stream = socket.getOutputStream();
                DataOutputStream commStream = new DataOutputStream(stream);
                commStream.write("1234567890123456".getBytes());
                socket.close();
                Log.d(TAG, "Client socket done");
            } catch (Exception e) {
                Log.e(TAG, e.toString());
            }
        }

    });
    clientThread.start();

It doesn't even connect to the server socket, it just waits until timeout. Is there anything I'm doing wrong here?

Thanks in advance.

Upvotes: 2

Views: 3161

Answers (1)

Yogeshwar Sharma
Yogeshwar Sharma

Reputation: 145

You cannot create a server socket with IP(192.168.43.1) on the device which has created the hotspot. So just reverse the server socket on another device that has been connected to the hotspot.

e.g. Let's say you have created hotspot on Device A and Device B has been connected to A so create the server socket on Device B with assigned local IP and create Socket instance in A by finding the IP of Device B.

Upvotes: 2

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