content: /*
   * Copyright (C) 2012 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package android.bluetooth;
  
  import android.annotation.UnsupportedAppUsage;
  import android.net.LocalSocket;
  import android.os.ParcelFileDescriptor;
  import android.os.ParcelUuid;
  import android.os.RemoteException;
  import android.util.Log;
  
  import java.io.Closeable;
  import java.io.FileDescriptor;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  import java.nio.ByteOrder;
  import java.util.Arrays;
  import java.util.Locale;
  import java.util.UUID;
  
  /**
   * A connected or connecting Bluetooth socket.
   *
   * <p>The interface for Bluetooth Sockets is similar to that of TCP sockets:
   * {@link java.net.Socket} and {@link java.net.ServerSocket}. On the server
   * side, use a {@link BluetoothServerSocket} to create a listening server
   * socket. When a connection is accepted by the {@link BluetoothServerSocket},
   * it will return a new {@link BluetoothSocket} to manage the connection.
   * On the client side, use a single {@link BluetoothSocket} to both initiate
   * an outgoing connection and to manage the connection.
   *
   * <p>The most common type of Bluetooth socket is RFCOMM, which is the type
   * supported by the Android APIs. RFCOMM is a connection-oriented, streaming
   * transport over Bluetooth. It is also known as the Serial Port Profile (SPP).
   *
   * <p>To create a {@link BluetoothSocket} for connecting to a known device, use
   * {@link BluetoothDevice#createRfcommSocketToServiceRecord
   * BluetoothDevice.createRfcommSocketToServiceRecord()}.
   * Then call {@link #connect()} to attempt a connection to the remote device.
   * This call will block until a connection is established or the connection
   * fails.
   *
   * <p>To create a {@link BluetoothSocket} as a server (or "host"), see the
   * {@link BluetoothServerSocket} documentation.
   *
   * <p>Once the socket is connected, whether initiated as a client or accepted
   * as a server, open the IO streams by calling {@link #getInputStream} and
   * {@link #getOutputStream} in order to retrieve {@link java.io.InputStream}
   * and {@link java.io.OutputStream} objects, respectively, which are
   * automatically connected to the socket.
   *
   * <p>{@link BluetoothSocket} is thread
   * safe. In particular, {@link #close} will always immediately abort ongoing
   * operations and close the socket.
   *
   * <p class="note"><strong>Note:</strong>
   * Requires the {@link android.Manifest.permission#BLUETOOTH} permission.
   *
   * <div class="special reference">
   * <h3>Developer Guides</h3>
   * <p>For more information about using Bluetooth, read the
   * <a href="{@docRoot}guide/topics/connectivity/bluetooth.html">Bluetooth</a> developer guide.</p>
   * </div>
   *
   * {@see BluetoothServerSocket}
   * {@see java.io.InputStream}
   * {@see java.io.OutputStream}
   */
  public final class BluetoothSocket implements Closeable {
      private static final String TAG = "BluetoothSocket";
      private static final boolean DBG = Log.isLoggable(TAG, Log.DEBUG);
      private static final boolean VDBG = Log.isLoggable(TAG, Log.VERBOSE);
  
      /** @hide */
      public static final int MAX_RFCOMM_CHANNEL = 30;
      /*package*/ static final int MAX_L2CAP_PACKAGE_SIZE = 0xFFFF;
  
      /** RFCOMM socket */
      public static final int TYPE_RFCOMM = 1;
  
      /** SCO socket */
      public static final int TYPE_SCO = 2;
  
      /** L2CAP socket */
      public static final int TYPE_L2CAP = 3;
  
      /** L2CAP socket on BR/EDR transport
       * @hide
       */
      public static final int TYPE_L2CAP_BREDR = TYPE_L2CAP;
  
      /** L2CAP socket on LE transport
       * @hide
       */
      public static final int TYPE_L2CAP_LE = 4;
  
      /*package*/ static final int EBADFD = 77;
      @UnsupportedAppUsage
      /*package*/ static final int EADDRINUSE = 98;
  
      /*package*/ static final int SEC_FLAG_ENCRYPT = 1;
      /*package*/ static final int SEC_FLAG_AUTH = 1 << 1;
      /*package*/ static final int BTSOCK_FLAG_NO_SDP = 1 << 2;
      /*package*/ static final int SEC_FLAG_AUTH_MITM = 1 << 3;
      /*package*/ static final int SEC_FLAG_AUTH_16_DIGIT = 1 << 4;
  
      private final int mType;  /* one of TYPE_RFCOMM etc */
      private BluetoothDevice mDevice;    /* remote device */
      private String mAddress;    /* remote address */
      private final boolean mAuth;
      private final boolean mEncrypt;
      private final BluetoothInputStream mInputStream;
      private final BluetoothOutputStream mOutputStream;
      private final ParcelUuid mUuid;
      private boolean mExcludeSdp = false; /* when true no SPP SDP record will be created */
      private boolean mAuthMitm = false;   /* when true Man-in-the-middle protection will be enabled*/
      private boolean mMin16DigitPin = false; /* Minimum 16 digit pin for sec mode 2 connections */
      @UnsupportedAppUsage
      private ParcelFileDescriptor mPfd;
      @UnsupportedAppUsage
      private LocalSocket mSocket;
      private InputStream mSocketIS;
      private OutputStream mSocketOS;
      @UnsupportedAppUsage
      private int mPort;  /* RFCOMM channel or L2CAP psm */
      private int mFd;
      private String mServiceName;
      private static final int PROXY_CONNECTION_TIMEOUT = 5000;
  
      private static final int SOCK_SIGNAL_SIZE = 20;
  
      private ByteBuffer mL2capBuffer = null;
      private int mMaxTxPacketSize = 0; // The l2cap maximum packet size supported by the peer.
      private int mMaxRxPacketSize = 0; // The l2cap maximum packet size that can be received.
  
      private enum SocketState {
          INIT,
          CONNECTED,
          LISTENING,
          CLOSED,
      }
  
      /** prevents all native calls after destroyNative() */
      private volatile SocketState mSocketState;
  
      /** protects mSocketState */
      //private final ReentrantReadWriteLock mLock;
  
      /**
       * Construct a BluetoothSocket.
       *
       * @param type type of socket
       * @param fd fd to use for connected socket, or -1 for a new socket
       * @param auth require the remote device to be authenticated
       * @param encrypt require the connection to be encrypted
       * @param device remote device that this socket can connect to
       * @param port remote port
       * @param uuid SDP uuid
       * @throws IOException On error, for example Bluetooth not available, or insufficient
       * privileges
       */
      /*package*/ BluetoothSocket(int type, int fd, boolean auth, boolean encrypt,
              BluetoothDevice device, int port, ParcelUuid uuid) throws IOException {
          this(type, fd, auth, encrypt, device, port, uuid, false, false);
      }
  
      /**
       * Construct a BluetoothSocket.
       *
       * @param type type of socket
       * @param fd fd to use for connected socket, or -1 for a new socket
       * @param auth require the remote device to be authenticated
       * @param encrypt require the connection to be encrypted
       * @param device remote device that this socket can connect to
       * @param port remote port
       * @param uuid SDP uuid
       * @param mitm enforce man-in-the-middle protection.
       * @param min16DigitPin enforce a minimum length of 16 digits for a sec mode 2 connection
       * @throws IOException On error, for example Bluetooth not available, or insufficient
       * privileges
       */
      /*package*/ BluetoothSocket(int type, int fd, boolean auth, boolean encrypt,
              BluetoothDevice device, int port, ParcelUuid uuid, boolean mitm, boolean min16DigitPin)
              throws IOException {
          if (VDBG) Log.d(TAG, "Creating new BluetoothSocket of type: " + type);
          if (type == BluetoothSocket.TYPE_RFCOMM && uuid == null && fd == -1
                  && port != BluetoothAdapter.SOCKET_CHANNEL_AUTO_STATIC_NO_SDP) {
              if (port < 1 || port > MAX_RFCOMM_CHANNEL) {
                  throw new IOException("Invalid RFCOMM channel: " + port);
              }
          }
          if (uuid != null) {
              mUuid = uuid;
          } else {
              mUuid = new ParcelUuid(new UUID(0, 0));
          }
          mType = type;
          mAuth = auth;
          mAuthMitm = mitm;
          mMin16DigitPin = min16DigitPin;
          mEncrypt = encrypt;
          mDevice = device;
          mPort = port;
          mFd = fd;
  
          mSocketState = SocketState.INIT;
  
          if (device == null) {
              // Server socket
              mAddress = BluetoothAdapter.getDefaultAdapter().getAddress();
          } else {
              // Remote socket
              mAddress = device.getAddress();
          }
          mInputStream = new BluetoothInputStream(this);
          mOutputStream = new BluetoothOutputStream(this);
      }
  
      private BluetoothSocket(BluetoothSocket s) {
          if (VDBG) Log.d(TAG, "Creating new Private BluetoothSocket of type: " + s.mType);
          mUuid = s.mUuid;
          mType = s.mType;
          mAuth = s.mAuth;
          mEncrypt = s.mEncrypt;
          mPort = s.mPort;
          mInputStream = new BluetoothInputStream(this);
          mOutputStream = new BluetoothOutputStream(this);
          mMaxRxPacketSize = s.mMaxRxPacketSize;
          mMaxTxPacketSize = s.mMaxTxPacketSize;
  
          mServiceName = s.mServiceName;
          mExcludeSdp = s.mExcludeSdp;
          mAuthMitm = s.mAuthMitm;
          mMin16DigitPin = s.mMin16DigitPin;
      }
  
      private BluetoothSocket acceptSocket(String remoteAddr) throws IOException {
          BluetoothSocket as = new BluetoothSocket(this);
          as.mSocketState = SocketState.CONNECTED;
          FileDescriptor[] fds = mSocket.getAncillaryFileDescriptors();
          if (DBG) Log.d(TAG, "socket fd passed by stack fds: " + Arrays.toString(fds));
          if (fds == null || fds.length != 1) {
              Log.e(TAG, "socket fd passed from stack failed, fds: " + Arrays.toString(fds));
              as.close();
              throw new IOException("bt socket acept failed");
          }
  
          as.mPfd = new ParcelFileDescriptor(fds[0]);
          as.mSocket = LocalSocket.createConnectedLocalSocket(fds[0]);
          as.mSocketIS = as.mSocket.getInputStream();
          as.mSocketOS = as.mSocket.getOutputStream();
          as.mAddress = remoteAddr;
          as.mDevice = BluetoothAdapter.getDefaultAdapter().getRemoteDevice(remoteAddr);
          return as;
      }
  
      /**
       * Construct a BluetoothSocket from address. Used by native code.
       *
       * @param type type of socket
       * @param fd fd to use for connected socket, or -1 for a new socket
       * @param auth require the remote device to be authenticated
       * @param encrypt require the connection to be encrypted
       * @param address remote device that this socket can connect to
       * @param port remote port
       * @throws IOException On error, for example Bluetooth not available, or insufficient
       * privileges
       */
      private BluetoothSocket(int type, int fd, boolean auth, boolean encrypt, String address,
              int port) throws IOException {
          this(type, fd, auth, encrypt, new BluetoothDevice(address), port, null, false, false);
      }
  
      /** @hide */
      @Override
      protected void finalize() throws Throwable {
          try {
              close();
          } finally {
              super.finalize();
          }
      }
  
      private int getSecurityFlags() {
          int flags = 0;
          if (mAuth) {
              flags |= SEC_FLAG_AUTH;
          }
          if (mEncrypt) {
              flags |= SEC_FLAG_ENCRYPT;
          }
          if (mExcludeSdp) {
              flags |= BTSOCK_FLAG_NO_SDP;
          }
          if (mAuthMitm) {
              flags |= SEC_FLAG_AUTH_MITM;
          }
          if (mMin16DigitPin) {
              flags |= SEC_FLAG_AUTH_16_DIGIT;
          }
          return flags;
      }
  
      /**
       * Get the remote device this socket is connecting, or connected, to.
       *
       * @return remote device
       */
      public BluetoothDevice getRemoteDevice() {
          return mDevice;
      }
  
      /**
       * Get the input stream associated with this socket.
       * <p>The input stream will be returned even if the socket is not yet
       * connected, but operations on that stream will throw IOException until
       * the associated socket is connected.
       *
       * @return InputStream
       */
      public InputStream getInputStream() throws IOException {
          return mInputStream;
      }
  
      /**
       * Get the output stream associated with this socket.
       * <p>The output stream will be returned even if the socket is not yet
       * connected, but operations on that stream will throw IOException until
       * the associated socket is connected.
       *
       * @return OutputStream
       */
      public OutputStream getOutputStream() throws IOException {
          return mOutputStream;
      }
  
      /**
       * Get the connection status of this socket, ie, whether there is an active connection with
       * remote device.
       *
       * @return true if connected false if not connected
       */
      public boolean isConnected() {
          return mSocketState == SocketState.CONNECTED;
      }
  
      /*package*/ void setServiceName(String name) {
          mServiceName = name;
      }
  
      /**
       * Attempt to connect to a remote device.
       * <p>This method will block until a connection is made or the connection
       * fails. If this method returns without an exception then this socket
       * is now connected.
       * <p>Creating new connections to
       * remote Bluetooth devices should not be attempted while device discovery
       * is in progress. Device discovery is a heavyweight procedure on the
       * Bluetooth adapter and will significantly slow a device connection.
       * Use {@link BluetoothAdapter#cancelDiscovery()} to cancel an ongoing
       * discovery. Discovery is not managed by the Activity,
       * but is run as a system service, so an application should always call
       * {@link BluetoothAdapter#cancelDiscovery()} even if it
       * did not directly request a discovery, just to be sure.
       * <p>{@link #close} can be used to abort this call from another thread.
       *
       * @throws IOException on error, for example connection failure
       */
      public void connect() throws IOException {
          if (mDevice == null) throw new IOException("Connect is called on null device");
  
          try {
              if (mSocketState == SocketState.CLOSED) throw new IOException("socket closed");
              IBluetooth bluetoothProxy =
                      BluetoothAdapter.getDefaultAdapter().getBluetoothService(null);
              if (bluetoothProxy == null) throw new IOException("Bluetooth is off");
              mPfd = bluetoothProxy.getSocketManager().connectSocket(mDevice, mType,
                      mUuid, mPort, getSecurityFlags());
              synchronized (this) {
                  if (DBG) Log.d(TAG, "connect(), SocketState: " + mSocketState + ", mPfd: " + mPfd);
                  if (mSocketState == SocketState.CLOSED) throw new IOException("socket closed");
                  if (mPfd == null) throw new IOException("bt socket connect failed");
                  FileDescriptor fd = mPfd.getFileDescriptor();
                  mSocket = LocalSocket.createConnectedLocalSocket(fd);
                  mSocketIS = mSocket.getInputStream();
                  mSocketOS = mSocket.getOutputStream();
              }
              int channel = readInt(mSocketIS);
              if (channel <= 0) {
                  throw new IOException("bt socket connect failed");
              }
              mPort = channel;
              waitSocketSignal(mSocketIS);
              synchronized (this) {
                  if (mSocketState == SocketState.CLOSED) {
                      throw new IOException("bt socket closed");
                  }
                  mSocketState = SocketState.CONNECTED;
              }
          } catch (RemoteException e) {
              Log.e(TAG, Log.getStackTraceString(new Throwable()));
              throw new IOException("unable to send RPC: " + e.getMessage());
          }
      }
  
      /**
       * Currently returns unix errno instead of throwing IOException,
       * so that BluetoothAdapter can check the error code for EADDRINUSE
       */
      /*package*/ int bindListen() {
          int ret;
          if (mSocketState == SocketState.CLOSED) return EBADFD;
          IBluetooth bluetoothProxy = BluetoothAdapter.getDefaultAdapter().getBluetoothService(null);
          if (bluetoothProxy == null) {
              Log.e(TAG, "bindListen fail, reason: bluetooth is off");
              return -1;
          }
          try {
              if (DBG) Log.d(TAG, "bindListen(): mPort=" + mPort + ", mType=" + mType);
              mPfd = bluetoothProxy.getSocketManager().createSocketChannel(mType, mServiceName,
                      mUuid, mPort, getSecurityFlags());
          } catch (RemoteException e) {
              Log.e(TAG, Log.getStackTraceString(new Throwable()));
              return -1;
          }
  
          // read out port number
          try {
              synchronized (this) {
                  if (DBG) {
                      Log.d(TAG, "bindListen(), SocketState: " + mSocketState + ", mPfd: " + mPfd);
                  }
                  if (mSocketState != SocketState.INIT) return EBADFD;
                  if (mPfd == null) return -1;
                  FileDescriptor fd = mPfd.getFileDescriptor();
                  if (fd == null) {
                      Log.e(TAG, "bindListen(), null file descriptor");
                      return -1;
                  }
  
                  if (DBG) Log.d(TAG, "bindListen(), Create LocalSocket");
                  mSocket = LocalSocket.createConnectedLocalSocket(fd);
                  if (DBG) Log.d(TAG, "bindListen(), new LocalSocket.getInputStream()");
                  mSocketIS = mSocket.getInputStream();
                  mSocketOS = mSocket.getOutputStream();
              }
              if (DBG) Log.d(TAG, "bindListen(), readInt mSocketIS: " + mSocketIS);
              int channel = readInt(mSocketIS);
              synchronized (this) {
                  if (mSocketState == SocketState.INIT) {
                      mSocketState = SocketState.LISTENING;
                  }
              }
              if (DBG) Log.d(TAG, "bindListen(): channel=" + channel + ", mPort=" + mPort);
              if (mPort <= -1) {
                  mPort = channel;
              } // else ASSERT(mPort == channel)
              ret = 0;
          } catch (IOException e) {
              if (mPfd != null) {
                  try {
                      mPfd.close();
                  } catch (IOException e1) {
                      Log.e(TAG, "bindListen, close mPfd: " + e1);
                  }
                  mPfd = null;
              }
              Log.e(TAG, "bindListen, fail to get port number, exception: " + e);
              return -1;
          }
          return ret;
      }
  
      /*package*/ BluetoothSocket accept(int timeout) throws IOException {
          BluetoothSocket acceptedSocket;
          if (mSocketState != SocketState.LISTENING) {
              throw new IOException("bt socket is not in listen state");
          }
          if (timeout > 0) {
              Log.d(TAG, "accept() set timeout (ms):" + timeout);
              mSocket.setSoTimeout(timeout);
          }
          String RemoteAddr = waitSocketSignal(mSocketIS);
          if (timeout > 0) {
              mSocket.setSoTimeout(0);
          }
          synchronized (this) {
              if (mSocketState != SocketState.LISTENING) {
                  throw new IOException("bt socket is not in listen state");
              }
              acceptedSocket = acceptSocket(RemoteAddr);
              //quick drop the reference of the file handle
          }
          return acceptedSocket;
      }
  
      /*package*/ int available() throws IOException {
          if (VDBG) Log.d(TAG, "available: " + mSocketIS);
          return mSocketIS.available();
      }
  
      /**
       * Wait until the data in sending queue is emptied. A polling version
       * for flush implementation. Used to ensure the writing data afterwards will
       * be packed in new RFCOMM frame.
       *
       * @throws IOException if an i/o error occurs.
       */
      @UnsupportedAppUsage
      /*package*/ void flush() throws IOException {
          if (mSocketOS == null) throw new IOException("flush is called on null OutputStream");
          if (VDBG) Log.d(TAG, "flush: " + mSocketOS);
          mSocketOS.flush();
      }
  
      /*package*/ int read(byte[] b, int offset, int length) throws IOException {
          int ret = 0;
          if (VDBG) Log.d(TAG, "read in:  " + mSocketIS + " len: " + length);
          if ((mType == TYPE_L2CAP) || (mType == TYPE_L2CAP_LE)) {
              int bytesToRead = length;
              if (VDBG) {
                  Log.v(TAG, "l2cap: read(): offset: " + offset + " length:" + length
                          + "mL2capBuffer= " + mL2capBuffer);
              }
              if (mL2capBuffer == null) {
                  createL2capRxBuffer();
              }
              if (mL2capBuffer.remaining() == 0) {
                  if (VDBG) Log.v(TAG, "l2cap buffer empty, refilling...");
                  if (fillL2capRxBuffer() == -1) {
                      return -1;
                  }
              }
              if (bytesToRead > mL2capBuffer.remaining()) {
                  bytesToRead = mL2capBuffer.remaining();
              }
              if (VDBG) {
                  Log.v(TAG, "get(): offset: " + offset
                          + " bytesToRead: " + bytesToRead);
              }
              mL2capBuffer.get(b, offset, bytesToRead);
              ret = bytesToRead;
          } else {
              if (VDBG) Log.v(TAG, "default: read(): offset: " + offset + " length:" + length);
              ret = mSocketIS.read(b, offset, length);
          }
          if (ret < 0) {
              throw new IOException("bt socket closed, read return: " + ret);
          }
          if (VDBG) Log.d(TAG, "read out:  " + mSocketIS + " ret: " + ret);
          return ret;
      }
  
      /*package*/ int write(byte[] b, int offset, int length) throws IOException {
  
          //TODO: Since bindings can exist between the SDU size and the
          //      protocol, we might need to throw an exception instead of just
          //      splitting the write into multiple smaller writes.
          //      Rfcomm uses dynamic allocation, and should not have any bindings
          //      to the actual message length.
          if (VDBG) Log.d(TAG, "write: " + mSocketOS + " length: " + length);
          if ((mType == TYPE_L2CAP) || (mType == TYPE_L2CAP_LE)) {
              if (length <= mMaxTxPacketSize) {
                  mSocketOS.write(b, offset, length);
              } else {
                  if (DBG) {
                      Log.w(TAG, "WARNING: Write buffer larger than L2CAP packet size!\n"
                              + "Packet will be divided into SDU packets of size "
                              + mMaxTxPacketSize);
                  }
                  int tmpOffset = offset;
                  int bytesToWrite = length;
                  while (bytesToWrite > 0) {
                      int tmpLength = (bytesToWrite > mMaxTxPacketSize)
                              ? mMaxTxPacketSize
                              : bytesToWrite;
                      mSocketOS.write(b, tmpOffset, tmpLength);
                      tmpOffset += tmpLength;
                      bytesToWrite -= tmpLength;
                  }
              }
          } else {
              mSocketOS.write(b, offset, length);
          }
          // There is no good way to confirm since the entire process is asynchronous anyway
          if (VDBG) Log.d(TAG, "write out: " + mSocketOS + " length: " + length);
          return length;
      }
  
      @Override
      public void close() throws IOException {
          Log.d(TAG, "close() this: " + this + ", channel: " + mPort + ", mSocketIS: " + mSocketIS
                  + ", mSocketOS: " + mSocketOS + "mSocket: " + mSocket + ", mSocketState: "
                  + mSocketState);
          if (mSocketState == SocketState.CLOSED) {
              return;
          } else {
              synchronized (this) {
                  if (mSocketState == SocketState.CLOSED) {
                      return;
                  }
                  mSocketState = SocketState.CLOSED;
                  if (mSocket != null) {
                      if (DBG) Log.d(TAG, "Closing mSocket: " + mSocket);
                      mSocket.shutdownInput();
                      mSocket.shutdownOutput();
                      mSocket.close();
                      mSocket = null;
                  }
                  if (mPfd != null) {
                      mPfd.close();
                      mPfd = null;
                  }
              }
          }
      }
  
      /*package */ void removeChannel() {
      }
  
      /*package */ int getPort() {
          return mPort;
      }
  
      /**
       * Get the maximum supported Transmit packet size for the underlying transport.
       * Use this to optimize the writes done to the output socket, to avoid sending
       * half full packets.
       *
       * @return the maximum supported Transmit packet size for the underlying transport.
       */
      public int getMaxTransmitPacketSize() {
          return mMaxTxPacketSize;
      }
  
      /**
       * Get the maximum supported Receive packet size for the underlying transport.
       * Use this to optimize the reads done on the input stream, as any call to read
       * will return a maximum of this amount of bytes - or for some transports a
       * multiple of this value.
       *
       * @return the maximum supported Receive packet size for the underlying transport.
       */
      public int getMaxReceivePacketSize() {
          return mMaxRxPacketSize;
      }
  
      /**
       * Get the type of the underlying connection.
       *
       * @return one of {@link #TYPE_RFCOMM}, {@link #TYPE_SCO} or {@link #TYPE_L2CAP}
       */
      public int getConnectionType() {
          if (mType == TYPE_L2CAP_LE) {
              // Treat the LE CoC to be the same type as L2CAP.
              return TYPE_L2CAP;
          }
          return mType;
      }
  
      /**
       * Change if a SDP entry should be automatically created.
       * Must be called before calling .bind, for the call to have any effect.
       *
       * @param excludeSdp <li>TRUE - do not auto generate SDP record. <li>FALSE - default - auto
       * generate SPP SDP record.
       * @hide
       */
      public void setExcludeSdp(boolean excludeSdp) {
          mExcludeSdp = excludeSdp;
      }
  
      /**
       * Set the LE Transmit Data Length to be the maximum that the BT Controller is capable of. This
       * parameter is used by the BT Controller to set the maximum transmission packet size on this
       * connection. This function is currently used for testing only.
       * @hide
       */
      public void requestMaximumTxDataLength() throws IOException {
          if (mDevice == null) {
              throw new IOException("requestMaximumTxDataLength is called on null device");
          }
  
          try {
              if (mSocketState == SocketState.CLOSED) {
                  throw new IOException("socket closed");
              }
              IBluetooth bluetoothProxy =
                      BluetoothAdapter.getDefaultAdapter().getBluetoothService(null);
              if (bluetoothProxy == null) {
                  throw new IOException("Bluetooth is off");
              }
  
              if (DBG) Log.d(TAG, "requestMaximumTxDataLength");
              bluetoothProxy.getSocketManager().requestMaximumTxDataLength(mDevice);
          } catch (RemoteException e) {
              Log.e(TAG, Log.getStackTraceString(new Throwable()));
              throw new IOException("unable to send RPC: " + e.getMessage());
          }
      }
  
      private String convertAddr(final byte[] addr) {
          return String.format(Locale.US, "%02X:%02X:%02X:%02X:%02X:%02X",
                  addr[0], addr[1], addr[2], addr[3], addr[4], addr[5]);
      }
  
      private String waitSocketSignal(InputStream is) throws IOException {
          byte[] sig = new byte[SOCK_SIGNAL_SIZE];
          int ret = readAll(is, sig);
          if (VDBG) {
              Log.d(TAG, "waitSocketSignal read " + SOCK_SIGNAL_SIZE + " bytes signal ret: " + ret);
          }
          ByteBuffer bb = ByteBuffer.wrap(sig);
          /* the struct in native is decorated with __attribute__((packed)), hence this is possible */
          bb.order(ByteOrder.nativeOrder());
          int size = bb.getShort();
          if (size != SOCK_SIGNAL_SIZE) {
              throw new IOException("Connection failure, wrong signal size: " + size);
          }
          byte[] addr = new byte[6];
          bb.get(addr);
          int channel = bb.getInt();
          int status = bb.getInt();
          mMaxTxPacketSize = (bb.getShort() & 0xffff); // Convert to unsigned value
          mMaxRxPacketSize = (bb.getShort() & 0xffff); // Convert to unsigned value
          String RemoteAddr = convertAddr(addr);
          if (VDBG) {
              Log.d(TAG, "waitSocketSignal: sig size: " + size + ", remote addr: "
                      + RemoteAddr + ", channel: " + channel + ", status: " + status
                      + " MaxRxPktSize: " + mMaxRxPacketSize + " MaxTxPktSize: " + mMaxTxPacketSize);
          }
          if (status != 0) {
              throw new IOException("Connection failure, status: " + status);
          }
          return RemoteAddr;
      }
  
      private void createL2capRxBuffer() {
          if ((mType == TYPE_L2CAP) || (mType == TYPE_L2CAP_LE)) {
              // Allocate the buffer to use for reads.
              if (VDBG) Log.v(TAG, "  Creating mL2capBuffer: mMaxPacketSize: " + mMaxRxPacketSize);
              mL2capBuffer = ByteBuffer.wrap(new byte[mMaxRxPacketSize]);
              if (VDBG) Log.v(TAG, "mL2capBuffer.remaining()" + mL2capBuffer.remaining());
              mL2capBuffer.limit(0); // Ensure we do a real read at the first read-request
              if (VDBG) {
                  Log.v(TAG, "mL2capBuffer.remaining() after limit(0):" + mL2capBuffer.remaining());
              }
          }
      }
  
      private int readAll(InputStream is, byte[] b) throws IOException {
          int left = b.length;
          while (left > 0) {
              int ret = is.read(b, b.length - left, left);
              if (ret <= 0) {
                  throw new IOException("read failed, socket might closed or timeout, read ret: "
                          + ret);
              }
              left -= ret;
              if (left != 0) {
                  Log.w(TAG, "readAll() looping, read partial size: " + (b.length - left)
                          + ", expect size: " + b.length);
              }
          }
          return b.length;
      }
  
      private int readInt(InputStream is) throws IOException {
          byte[] ibytes = new byte[4];
          int ret = readAll(is, ibytes);
          if (VDBG) Log.d(TAG, "inputStream.read ret: " + ret);
          ByteBuffer bb = ByteBuffer.wrap(ibytes);
          bb.order(ByteOrder.nativeOrder());
          return bb.getInt();
      }
  
      private int fillL2capRxBuffer() throws IOException {
          mL2capBuffer.rewind();
          int ret = mSocketIS.read(mL2capBuffer.array());
          if (ret == -1) {
              // reached end of stream - return -1
              mL2capBuffer.limit(0);
              return -1;
          }
          mL2capBuffer.limit(ret);
          return ret;
      }
  
  
  }
  