Android: Bluetooth - can't establish connection, IOException "Connection reset by peer"

I'd be very grateful if someone could help me. I'm trying to connect to some custom bluetooth hardware a client has provided me. I've followed the API docs religiously and am using the following code (mostly copied and sewn together from the official docs) to establish a socket connection with the bluetooth hardware, which a user selects as a device from a lis开发者_如何学运维tview within my Android application.

private class CommunicationThread extends Thread {
    private final BluetoothSocket mmSocket;

    public CommunicationThread(BluetoothDevice device) {
        super();
        // use a temporary object that is later assigned to mmSocket,
        // because mmSocket is final
        BluetoothSocket tmp = null;
        BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        // get a BluetoothSocket to connect with the given BluetoothDevice
        try {
            // create rf communication socket using a unique identifier for this app
            tmp = device.createRfcommSocketToServiceRecord(UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"));
        } catch (Exception e) {
            Log.d("An exception occurred during bluetooth rf communication server socket creation","NDB",e);
        }
        mmSocket = tmp;

        // cancel discovery because it will slow down the connection
        mBluetoothAdapter.cancelDiscovery();
    }

    public void run() {
        try {
            // connect the device through the socket. This will block
            // until it succeeds or throws an exception
            mmSocket.connect();
        } catch (IOException e) {
            Log.d("An exception occurred during bluetooth socket connection","NDB",e);
            // unable to connect; close the socket and get out
            try {
                mmSocket.close();
            } catch (IOException closeExc) {
                Log.d("An exception occurred while attempting to close bluetooth socket","NDB",closeExc);
            }
            return;
        }

        // do work to manage the connection
        manageConnectedSocket();
    }

    private void manageConnectedSocket() {
        InputStream tmpIn = null;

        // get the input steram, use temp object because
        // member stream is final
        try {
            tmpIn = mmSocket.getInputStream();
        } catch (IOException e) {
            Log.d("An exception occurred during bluetooth io stream creation","NDB",e);
        }

        final InputStream mmInStream = tmpIn;

        byte[] buffer = new byte[1024];  // buffer store for the stream
        int bytes; // bytes returned from read()

        // keep listening to the InputStream until an exception occurs
        while (true) {
            try {
                // read from the InputStream
                bytes = mmInStream.read(buffer);
                // send the obtained bytes to the message handler
                bluetoothHandler.obtainMessage(/*MESSAGE_READ*/1, bytes, -1, buffer).sendToTarget();
            } catch (IOException e) {
                break;
            }
        }
    }

    /** Cancels an in-progress connection, and closes the socket */
    public void cancel() {
        try {
            mmSocket.close();
        } catch (IOException e) { }
    }
}

The problem is that upon attempting to connect to the hardware within run() using mmSocket.connect() the call blocks for a few seconds then throws an exception with description java.io.IOException: Connection reset by peer. I've pasted the relevant LogCat output below, with surrounding lines for your consideration.

05-07 13:29:08.675: INFO/ActivityThread(1370): Receiving broadcast android.bleutooth.device.action.UUID seq=-1 to android.app.ActivityThread$PackageInfo$ReceiverDispatcher@2fd75738
05-07 13:29:08.675: ERROR/ActivityThread(1370): start dispatch OnReceive message,mRegistered=true mCurOrdered=false intent=Intent { act=android.bleutooth.device.action.UUID (has extras) } receiver = com.android.settings.bluetooth.BluetoothEventRedirector$1@2fd74d98
05-07 13:29:08.675: VERBOSE/BluetoothEventRedirector(1370): Received android.bleutooth.device.action.UUID
05-07 13:29:08.675: ERROR/xubo(1370): mBroadcastReceiver receive msg = android.bleutooth.device.action.UUID
05-07 13:29:08.685: ERROR/ActivityThread(1370): exit dispatch OnReceive message,mRegistered=true mCurOrdered=false
05-07 13:29:15.455: DEBUG/An exception occurred during bluetooth socket connection(9827): NDB
05-07 13:29:15.455: DEBUG/An exception occurred during bluetooth socket connection(9827): java.io.IOException: Connection reset by peer
05-07 13:29:15.455: DEBUG/An exception occurred during bluetooth socket connection(9827):     at android.bluetooth.BluetoothSocket.connectNative(Native Method)
05-07 13:29:15.455: DEBUG/An exception occurred during bluetooth socket connection(9827):     at android.bluetooth.BluetoothSocket.connect(BluetoothSocket.java:204)
05-07 13:29:15.455: DEBUG/An exception occurred during bluetooth socket connection(9827):     at com.ndb.proj.Communicator$CommunicationThread.run(Communicator.java:157)
05-07 13:29:18.595: DEBUG/bluez/src/device.c(8031): /org/bluez/8031/hci0/dev_00_06_66_05_70_E7: canceling authentication request
05-07 13:29:18.595: ERROR/BluetoothEventLoop.cpp(1204): event_filter: Received signal org.bluez.Device:PropertyChanged from /org/bluez/8031/hci0/dev_00_06_66_05_70_E7
05-07 13:29:18.595: DEBUG/BluetoothEventLoop(1204): Device property changed:00:06:66:05:70:E7property:Connected
05-07 13:29:18.605: INFO/ActivityThread(1204): Receiving broadcast android.bluetooth.device.action.ACL_DISCONNECTED seq=-1 to android.app.ActivityThread$PackageInfo$ReceiverDispatcher@2fe7b918
05-07 13:29:18.605: ERROR/ActivityThread(1204): start dispatch OnReceive message,mRegistered=true mCurOrdered=false intent=Intent { act=android.bluetooth.device.action.ACL_DISCONNECTED (has extras) } receiver = android.server.BluetoothA2dpService$1@2fdafb58
05-07 13:29:18.615: ERROR/ActivityThread(1204): exit dispatch OnReceive message,mRegistered=true mCurOrdered=false
05-07 13:29:18.615: INFO/ActivityThread(1370): Receiving broadcast android.bluetooth.device.action.PAIRING_CANCEL seq=-1 to android.app.ActivityThread$PackageInfo$ReceiverDispatcher@2fd75738
05-07 13:29:18.625: ERROR/ActivityThread(1370): start dispatch OnReceive message,mRegistered=true mCurOrdered=false intent=Intent { act=android.bluetooth.device.action.PAIRING_CANCEL } receiver = com.android.settings.bluetooth.BluetoothEventRedirector$1@2fd74d98
05-07 13:29:18.625: VERBOSE/BluetoothEventRedirector(1370): Received android.bluetooth.device.action.PAIRING_CANCEL
05-07 13:29:18.625: ERROR/xubo(1370): mBroadcastReceiver receive msg = android.bluetooth.device.action.PAIRING_CANCEL
05-07 13:29:18.625: ERROR/ActivityThread(1370): exit dispatch OnReceive message,mRegistered=true mCurOrdered=false

The client has informed that the 'pairing code' is 1234. However, my android phone pairs fine with the device without specifying this. I've verified as such by entering Bluetooth settings, and indeed the device is reported as paired.

Can anyone suggest what's going wrong?

Darn, I was just about to post an answer and I see you had fixed it :)

The key was in this line:

05-07 13:29:18.595: DEBUG/bluez/src/device.c(8031): /org/bluez/8031/hci0/dev_00_06_66_05_70_E7: canceling authentication request

Which indicates that Bluetooth pairing needed to happen, but didn't take place.

So it turned out the issue was with the pairing code not being entered (duh!). I had programmatically paired with the device, which did not request any pairing code input, thus the pairing was improper.

The fix was to enter Settings -> Wireless & networks -> Bluetooth settings, long press on the "paired" device and select Unpair, then single press on the device which produced a Bluetooth pairing request window with textfield, into which I typed the PIN (pairing code).

After this was done, pairing was successful and the above code worked perfectly.