https://source.android.com/ 
/*
 * 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.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.

The interface for Bluetooth Sockets is similar to that of TCP sockets: Socket and ServerSocket. On the server side, use a BluetoothServerSocket to create a listening server socket. When a connection is accepted by the BluetoothServerSocket, it will return a new BluetoothSocket to manage the connection. On the client side, use a single BluetoothSocket to both initiate an outgoing connection and to manage the connection. 
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).

To create a BluetoothSocket for connecting to a known device, use 
BluetoothDevice.createRfcommSocketToServiceRecord(). Then call connect() to attempt a connection to the remote device. This call will block until a connection is established or the connection fails. 
To create a BluetoothSocket as a server (or "host"), see the BluetoothServerSocket documentation. 
Once the socket is connected, whether initiated as a client or accepted as a server, open the IO streams by calling getInputStream and getOutputStream in order to retrieve InputStream and OutputStream objects, respectively, which are automatically connected to the socket. 
BluetoothSocket is thread safe. In particular, close will always immediately abort ongoing operations and close the socket. 
Note: Requires the BLUETOOTH.BLUETOOTH permission. 


Developer Guides


For more information about using Bluetooth, read the
Bluetooth developer guide.



{@see BluetoothServerSocket}
{@see java.io.InputStream}
{@see java.io.OutputStream}

/**
 * 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
/** @hide */
    public static final int MAX_RFCOMM_CHANNEL = 30;
    /*package*/ static final int MAX_L2CAP_PACKAGE_SIZE = 0xFFFF;

    
RFCOMM socket 
/** RFCOMM socket */
    public static final int TYPE_RFCOMM = 1;

    
SCO socket 
/** SCO socket */
    public static final int TYPE_SCO = 2;

    
L2CAP socket 
/** L2CAP socket */
    public static final int TYPE_L2CAP = 3;

    
L2CAP socket on BR/EDR transport

@hide
/** L2CAP socket on BR/EDR transport
     * @hide
     */
    public static final int TYPE_L2CAP_BREDR = TYPE_L2CAP;

    
L2CAP socket on LE transport

@hide
/** L2CAP socket on LE transport
     * @hide
     */
    public static final int TYPE_L2CAP_LE = 4;

    /*package*/ static final int EBADFD = 77;
    /*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 */
    private ParcelFileDescriptor mPfd;
    private LocalSocket mSocket;
    private InputStream mSocketIS;
    private OutputStream mSocketOS;
    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() 
/** prevents all native calls after destroyNative() */
    private volatile SocketState mSocketState;

    /** protects mSocketState */
    //private final ReentrantReadWriteLock mLock;

    
Construct a BluetoothSocket.

Params:
  • type – type of socket
  • fd – fd to use for connected socket, or -1 for a new socket
  • auth – require the remote device to be authenticated
  • encrypt – require the connection to be encrypted
  • device – remote device that this socket can connect to
  • port – remote port
  • uuid – SDP uuid
Throws:
  • IOException – On error, for example Bluetooth not available, or insufficient
privileges
/**
     * 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.

Params:
  • type – type of socket
  • fd – fd to use for connected socket, or -1 for a new socket
  • auth – require the remote device to be authenticated
  • encrypt – require the connection to be encrypted
  • device – remote device that this socket can connect to
  • port – remote port
  • uuid – SDP uuid
  • mitm – enforce man-in-the-middle protection.
  • 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
/**
     * 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.

Params:
  • type – type of socket
  • fd – fd to use for connected socket, or -1 for a new socket
  • auth – require the remote device to be authenticated
  • encrypt – require the connection to be encrypted
  • address – remote device that this socket can connect to
  • port – remote port
Throws:
  • IOException – On error, for example Bluetooth not available, or insufficient
privileges
/**
     * 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
/** @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.

Returns:remote device
/**
     * 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.

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.

Returns:InputStream
/**
     * 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.

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.

Returns:OutputStream
/**
     * 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.

Returns:true if connected false if not connected
/**
     * 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.

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.

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 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 BluetoothAdapter.cancelDiscovery() even if it did not directly request a discovery, just to be sure. 
close can be used to abort this call from another thread. 
Throws:
  • IOException – on error, for example connection failure
/**
     * 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

/**
     * 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.
/**
     * 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.
     */
    /*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.

Returns:the maximum supported Transmit packet size for the underlying transport.
/**
     * 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.

Returns:the maximum supported Receive packet size for the underlying transport.
/**
     * 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.

Returns:one of TYPE_RFCOMM, TYPE_SCO or TYPE_L2CAP
/**
     * Get the type of the underlying connection.
     *
     * @return one of {@link #TYPE_RFCOMM}, {@link #TYPE_SCO} or {@link #TYPE_L2CAP}
     */
    public int getConnectionType() {
        return mType;
    }

    
Change if a SDP entry should be automatically created.
Must be called before calling .bind, for the call to have any effect.

Params:
  • excludeSdp – 
  • TRUE - do not auto generate SDP record. 
  • FALSE - default - auto
generate SPP SDP record.
@hide
/**
     * 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
/**
     * 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;
    }


}