Linux Bluetooth not finding Android Service with UUID

Question

I am trying to write a program on an embedded system running GUMSTIX(Linux) to connect and talk to an Android 2.x device over bluetooth. The GUMSTIX is the client and the Android is the server. I am trying to find the channel number that my Android service uses so that the GUMSTIX can connect to it but for some reason my routine isn't returning a channel number because it doesn't seem to find a service with a matching UUID.

I suspect that the UUID provided to the GUMSTIX routine and the UUID on the Android device are not actually the same number. Android requires a 128 bit UUID :

From the Android Documentation:

UUID is an immutable representation of a 128-bit universally unique identifier (UUID).

There are multiple, variant layouts of UUIDs, but this class is based upon variant 2 of RFC 4122, the Leach-Salz variant. This class can be used to model alternate variants, but most of the methods will be unsupported in those cases; see each method for

UUID used in android:

public static final String UUID_STRING = "00000000-0000-0000-0000-00000000ABCD";
private static final UUID MY_UUID = UUID.fromString(UUID_STRING);

C Code in GUMSTIX Look for comment indicating where it fails

int main(int argc , char **argv)
{
//Android wants a 128 bit UUID why are we only giving a 32 bit UUID
uint32_t svc_uuid_int[] = { 0 , 0 , 0 , 0xABCD } ;

int status ;
bdaddr_t target ;
uuid_t svc_uuid ;
sdp_list_t *response_list , *search_list , *attrid_list ;
sdp_session_t *session = 0;
uint32_t range = 0x0000ffff ;
uint8_t port = 0;

if(argc < 2)
{
    fprintf(stderr , "usage: %s <bt_addr>\n" , argv [ 0 ] ) ;
    exit ( 2 ) ;
}

str2ba ( argv[1] , &target ) ;
// connect to the SDP server running on the remote machine
session = sdp_connect ( BDADDR_ANY, &target, SDP_RETRY_IF_BUSY  );
//  printf("session %u\n",session);

sdp_uuid128_create( &svc_uuid, &svc_uuid_int ) ;
search_list = sdp_list_append( 0, &svc_uuid ) ;
attrid_list = sdp_list_append( 0, &range ) ;

// get a list of service records that have UUID 0xabcd
response_list = NULL ;   //ERROR: response_list SHOULD GET INITIALIZED BUT IT STAYS NULL CAUSING THE PROGRAM TO NEVER ENTER THE FOR LOOP BELOW.
status = sdp_service_search_attr_req(session , search_list , SDP_ATTR_REQ_RANGE , attrid_list, &response_list ) ;
printf("status %d\n",status);

if( status == 0 )
{
    sdp_list_t *proto_list = NULL ;
    sdp_list_t *r = response_list ;
    // go through each of the service records
    for ( ; r ; r = r->next )
    {
        sdp_record_t *rec = (sdp_record_t * ) r->data ;
        // get a list of the protocol sequences
        if( sdp_get_access_protos( rec, &proto_list ) == 0 ) 
        {
            // get the RFCOMM port number
            port = sdp_get_proto_port( proto_list , RFCOMM_UUID ) ;
            sdp_list_free( proto_list, 0 );
        }
        sdp_record_free( rec ) ;
    }
}

sdp_list_free( response_list, 0 );
sdp_list_free( search_list, 0 );
sdp_list_free( attrid_list, 0 );
sdp_close( session ) ;
if( port != 0 )
{
    printf( "found service running on RFCOMM port %d\n" , port ) ;
}
return 0;

}

EDIT:

Android code for the acceptThread(accepts connections), ConnectThread(completes the connection), and ConnectedThread(maintains the connection, establish handler)

/**
 * This thread runs while listening for incoming connections. It behaves
 * like a server-side client. It runs until a connection is accepted
 * (or until canceled).
 */
private class AcceptThread extends Thread {
    // The local server socket
    private final BluetoothServerSocket mmServerSocket;

    public AcceptThread() {
        BluetoothServerSocket tmp = null;

        // Create a new listening server socket
        try {
            tmp = mAdapter.listenUsingRfcommWithServiceRecord(NAME, MY_UUID);
        } catch (IOException e) {
            Log.e(TAG, "listen() failed", e);
        }
        mmServerSocket = tmp;
    }

    public void run() {
        if (D) Log.d(TAG, "BEGIN mAcceptThread" + this);
        setName("AcceptThread");
        BluetoothSocket socket = null;

        // Listen to the server socket if we're not connected
        while (mState != STATE_CONNECTED) {
            try {
                // This is a blocking call and will only return on a
                // successful connection or an exception
                if(D) Log.i("prism", "Waiting to connect************");
                socket = mmServerSocket.accept();
                if(D) Log.i("prism", "We have accepted connection and are connected***************");
            } catch (IOException e) {
                Log.e(TAG, "accept() failed", e);
                break;
            }

            // If a connection was accepted
            if (socket != null) {
                synchronized (BluetoothServer.this) {
                    switch (mState) {
                    case STATE_LISTEN:
                    case STATE_CONNECTING:
                        // Situation normal. Start the connected thread.
                        connected(socket, socket.getRemoteDevice());
                        break;
                    case STATE_NONE:
                    case STATE_CONNECTED:
                        // Either not ready or already connected. Terminate new socket.
                        try {
                            if (D) Log.i("prism", "Bluetooth already connected, abandoning request from " + socket.getRemoteDevice().getName());
                            socket.close();
                        } catch (IOException e) {
                            Log.e(TAG, "Could not close unwanted socket", e);
                        }
                        break;
                    }
                }
            }
        }
        if (D) Log.i(TAG, "END mAcceptThread");
    }

    public void cancel() {
        if (D) Log.d(TAG, "cancel " + this);
        try {
            mmServerSocket.close();
        } catch (IOException e) {
            Log.e(TAG, "close() of server failed", e);
        }
    }
}

/**
 * This thread runs while attempting to make an outgoing connection
 * with a device. It runs straight through; the connection either
 * succeeds or fails.
 */
private class ConnectThread extends Thread {
    private final BluetoothSocket mmSocket;
    private final BluetoothDevice mmDevice;

    public ConnectThread(BluetoothDevice device) {
        mmDevice = device;
        BluetoothSocket tmp = null;

        // Get a BluetoothSocket for a connection with the
        // given BluetoothDevice
        try {
            tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
        } catch (IOException e) {
            Log.e(TAG, "create() failed", e);
        }
        mmSocket = tmp;
    }

    public void run() {
        Log.i(TAG, "BEGIN mConnectThread");
        setName("ConnectThread");

        // Always cancel discovery because it will slow down a connection
        mAdapter.cancelDiscovery();

        // Make a connection to the BluetoothSocket
        try {
            // This is a blocking call and will only return on a
            // successful connection or an exception
            Log.i(TAG, "mmSocket.connect() is initiaiting in the ConnectThread");
            mmSocket.connect();
            Log.i(TAG, "mmSocket.connect() complete...");
        } catch (IOException e) {
            Log.e(TAG, "Connection attempt failed, closing the socket");
            connectionFailed();
            // Close the socket
            try {
                mmSocket.close();
            } catch (IOException e2) {
                Log.e(TAG, "unable to close() socket during connection failure", e2);
            }
            // Start the service over to restart listening mode
            BluetoothServer.this.start();
            return;
        }

        // Reset the ConnectThread because we're done
        synchronized (BluetoothServer.this) {
            mConnectThread = null;
        }

        // Start the connected thread
        connected(mmSocket, mmDevice);
    }

    public void cancel() {
        try {
            mmSocket.close();
        } catch (IOException e) {
            Log.e(TAG, "close() of connect socket failed", e);
        }
    }
}

/**
 * This thread runs during a connection with a remote device.
 * It handles all incoming and outgoing transmissions.
 */
private class ConnectedThread extends Thread {
    private final BluetoothSocket mmSocket;
    private final InputStream mmInStream;
    private final OutputStream mmOutStream;

    public ConnectedThread(BluetoothSocket socket) {
        Log.d(TAG, "create ConnectedThread");
        mmSocket = socket;
        InputStream tmpIn = null;
        OutputStream tmpOut = null;

        // Get the BluetoothSocket input and output streams
        try {
            tmpIn = socket.getInputStream();
            tmpOut = socket.getOutputStream();
        } catch (IOException e) {
            Log.e(TAG, "temp sockets not created", e);
        }

        mmInStream = tmpIn;
        mmOutStream = tmpOut;
    }

    public void run() {
        Log.i(TAG, "BEGIN mConnectedThread");
        byte[] buffer = new byte[1024];
        int bytes;

        // Keep listening to the InputStream while connected
        while (true) {
            try {
                // Read from the InputStream
                bytes = mmInStream.read(buffer);

                // Send the obtained bytes to the UI Activity
                mHandler.obtainMessage(Bluetooth.MESSAGE_READ, bytes, -1, buffer)
                        .sendToTarget();
            } catch (IOException e) {
                Log.e(TAG, "disconnected", e);
                connectionLost();
                break;
            }
        }
    }

The Android code was adopted from the Bluetooth Chat example here

Answer 1

Do you have any service (typically over RFCOMM/SPP) with UUID { 0 , 0 , 0 , 0xABCD } running on the Android device ?

You will probably (programmatically create the service with the specified UUID and have it running on the device to be able to connect to it.

Quoting from Android Documentation:

**

public BluetoothServerSocket listenUsingRfcommWithServiceRecord (String name, UUID uuid)
Create a listening, secure RFCOMM Bluetooth socket with Service Record.
A remote device connecting to this socket will be authenticated and communication on this socket will be encrypted.
Use accept() to retrieve incoming connections from a listening BluetoothServerSocket.
The system will assign an unused RFCOMM channel to listen on.
The system will also register a Service Discovery Protocol (SDP) record with the local SDP server containing the specified UUID, service name, and auto-assigned channel. Remote Bluetooth devices can use the same UUID to query our SDP server and discover which channel to connect to. This SDP record will be removed when this socket is closed, or if this application closes unexpectedly.
Use createRfcommSocketToServiceRecord(UUID) to connect to this socket from another device using the same UUID.

**