Java tutorial
/* * 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(publicAlternatives = "Use {@link BluetoothSocket} public API instead.") 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; } }