Home | History | Annotate | Download | only in handover
      1 /*
      2  * Copyright (C) 2012 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.nfc.handover;
     18 
     19 import java.nio.BufferUnderflowException;
     20 import java.nio.ByteBuffer;
     21 import java.nio.ByteOrder;
     22 import java.nio.charset.StandardCharsets;
     23 import java.util.ArrayList;
     24 import java.nio.charset.Charset;
     25 import java.util.Arrays;
     26 import java.util.Random;
     27 
     28 import android.bluetooth.BluetoothAdapter;
     29 import android.bluetooth.BluetoothClass;
     30 import android.bluetooth.BluetoothDevice;
     31 import android.bluetooth.BluetoothUuid;
     32 import android.bluetooth.OobData;
     33 import android.content.Context;
     34 import android.content.Intent;
     35 import android.nfc.FormatException;
     36 import android.nfc.NdefMessage;
     37 import android.nfc.NdefRecord;
     38 import android.os.ParcelUuid;
     39 import android.os.UserHandle;
     40 import android.util.Log;
     41 
     42 /**
     43  * Manages handover of NFC to other technologies.
     44  */
     45 public class HandoverDataParser {
     46     private static final String TAG = "NfcHandover";
     47     private static final boolean DBG = false;
     48 
     49     private static final byte[] TYPE_BT_OOB = "application/vnd.bluetooth.ep.oob"
     50             .getBytes(StandardCharsets.US_ASCII);
     51     private static final byte[] TYPE_BLE_OOB = "application/vnd.bluetooth.le.oob"
     52             .getBytes(StandardCharsets.US_ASCII);
     53 
     54     private static final byte[] TYPE_NOKIA = "nokia.com:bt".getBytes(StandardCharsets.US_ASCII);
     55 
     56     private static final byte[] RTD_COLLISION_RESOLUTION = {0x63, 0x72}; // "cr";
     57 
     58     private static final int CARRIER_POWER_STATE_INACTIVE = 0;
     59     private static final int CARRIER_POWER_STATE_ACTIVE = 1;
     60     private static final int CARRIER_POWER_STATE_ACTIVATING = 2;
     61     private static final int CARRIER_POWER_STATE_UNKNOWN = 3;
     62 
     63     private static final int BT_HANDOVER_TYPE_MAC = 0x1B;
     64     private static final int BT_HANDOVER_TYPE_LE_ROLE = 0x1C;
     65     private static final int BT_HANDOVER_TYPE_LONG_LOCAL_NAME = 0x09;
     66     private static final int BT_HANDOVER_TYPE_SHORT_LOCAL_NAME = 0x08;
     67     private static final int BT_HANDOVER_TYPE_16_BIT_UUIDS_PARTIAL = 0x02;
     68     private static final int BT_HANDOVER_TYPE_16_BIT_UUIDS_COMPLETE = 0x03;
     69     private static final int BT_HANDOVER_TYPE_32_BIT_UUIDS_PARTIAL = 0x04;
     70     private static final int BT_HANDOVER_TYPE_32_BIT_UUIDS_COMPLETE = 0x05;
     71     private static final int BT_HANDOVER_TYPE_128_BIT_UUIDS_PARTIAL = 0x06;
     72     private static final int BT_HANDOVER_TYPE_128_BIT_UUIDS_COMPLETE = 0x07;
     73     private static final int BT_HANDOVER_TYPE_CLASS_OF_DEVICE = 0x0D;
     74     private static final int BT_HANDOVER_TYPE_SECURITY_MANAGER_TK = 0x10;
     75     private static final int BT_HANDOVER_TYPE_APPEARANCE = 0x19;
     76     private static final int BT_HANDOVER_TYPE_LE_SC_CONFIRMATION = 0x22;
     77     private static final int BT_HANDOVER_TYPE_LE_SC_RANDOM = 0x23;
     78 
     79     public static final int BT_HANDOVER_LE_ROLE_CENTRAL_ONLY = 0x01;
     80 
     81     public static final int SECURITY_MANAGER_TK_SIZE = 16;
     82     public static final int SECURITY_MANAGER_LE_SC_C_SIZE = 16;
     83     public static final int SECURITY_MANAGER_LE_SC_R_SIZE = 16;
     84     private static final int CLASS_OF_DEVICE_SIZE = 3;
     85 
     86     private final BluetoothAdapter mBluetoothAdapter;
     87 
     88     private final Object mLock = new Object();
     89     // Variables below synchronized on mLock
     90 
     91     private String mLocalBluetoothAddress;
     92 
     93     public static class BluetoothHandoverData {
     94         public boolean valid = false;
     95         public BluetoothDevice device;
     96         public String name;
     97         public boolean carrierActivating = false;
     98         public int transport = BluetoothDevice.TRANSPORT_AUTO;
     99         public OobData oobData;
    100         public ParcelUuid[] uuids = null;
    101         public BluetoothClass btClass = null;
    102     }
    103 
    104     public static class IncomingHandoverData {
    105         public final NdefMessage handoverSelect;
    106         public final BluetoothHandoverData handoverData;
    107 
    108         public IncomingHandoverData(NdefMessage handoverSelect,
    109                                     BluetoothHandoverData handoverData) {
    110             this.handoverSelect = handoverSelect;
    111             this.handoverData = handoverData;
    112         }
    113     }
    114 
    115     public HandoverDataParser() {
    116         mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    117     }
    118 
    119     static NdefRecord createCollisionRecord() {
    120         byte[] random = new byte[2];
    121         new Random().nextBytes(random);
    122         return new NdefRecord(NdefRecord.TNF_WELL_KNOWN, RTD_COLLISION_RESOLUTION, null, random);
    123     }
    124 
    125     NdefRecord createBluetoothAlternateCarrierRecord(boolean activating) {
    126         byte[] payload = new byte[4];
    127         payload[0] = (byte) (activating ? CARRIER_POWER_STATE_ACTIVATING :
    128             CARRIER_POWER_STATE_ACTIVE);  // Carrier Power State: Activating or active
    129         payload[1] = 1;   // length of carrier data reference
    130         payload[2] = 'b'; // carrier data reference: ID for Bluetooth OOB data record
    131         payload[3] = 0;  // Auxiliary data reference count
    132         return new NdefRecord(NdefRecord.TNF_WELL_KNOWN, NdefRecord.RTD_ALTERNATIVE_CARRIER, null,
    133                 payload);
    134     }
    135 
    136     NdefRecord createBluetoothOobDataRecord() {
    137         byte[] payload = new byte[8];
    138         // Note: this field should be little-endian per the BTSSP spec
    139         // The Android 4.1 implementation used big-endian order here.
    140         // No single Android implementation has ever interpreted this
    141         // length field when parsing this record though.
    142         payload[0] = (byte) (payload.length & 0xFF);
    143         payload[1] = (byte) ((payload.length >> 8) & 0xFF);
    144 
    145         synchronized (mLock) {
    146             if (mLocalBluetoothAddress == null) {
    147                 mLocalBluetoothAddress = mBluetoothAdapter.getAddress();
    148             }
    149 
    150             byte[] addressBytes = addressToReverseBytes(mLocalBluetoothAddress);
    151             if (addressBytes != null) {
    152                 System.arraycopy(addressBytes, 0, payload, 2, 6);
    153             } else {
    154                 // don't cache unknown result
    155                 mLocalBluetoothAddress = null;
    156             }
    157         }
    158 
    159         return new NdefRecord(NdefRecord.TNF_MIME_MEDIA, TYPE_BT_OOB, new byte[]{'b'}, payload);
    160     }
    161 
    162     public boolean isHandoverSupported() {
    163         return (mBluetoothAdapter != null);
    164     }
    165 
    166     public NdefMessage createHandoverRequestMessage() {
    167         if (mBluetoothAdapter == null) {
    168             return null;
    169         }
    170 
    171         NdefRecord[] dataRecords = new NdefRecord[] {
    172                 createBluetoothOobDataRecord()
    173         };
    174         return new NdefMessage(
    175                 createHandoverRequestRecord(),
    176                 dataRecords);
    177     }
    178 
    179     NdefMessage createBluetoothHandoverSelectMessage(boolean activating) {
    180         return new NdefMessage(createHandoverSelectRecord(
    181                 createBluetoothAlternateCarrierRecord(activating)),
    182                 createBluetoothOobDataRecord());
    183     }
    184 
    185     NdefRecord createHandoverSelectRecord(NdefRecord alternateCarrier) {
    186         NdefMessage nestedMessage = new NdefMessage(alternateCarrier);
    187         byte[] nestedPayload = nestedMessage.toByteArray();
    188 
    189         ByteBuffer payload = ByteBuffer.allocate(nestedPayload.length + 1);
    190         payload.put((byte)0x12);  // connection handover v1.2
    191         payload.put(nestedPayload);
    192 
    193         byte[] payloadBytes = new byte[payload.position()];
    194         payload.position(0);
    195         payload.get(payloadBytes);
    196         return new NdefRecord(NdefRecord.TNF_WELL_KNOWN, NdefRecord.RTD_HANDOVER_SELECT, null,
    197                 payloadBytes);
    198     }
    199 
    200     NdefRecord createHandoverRequestRecord() {
    201         NdefRecord[] messages = new NdefRecord[] {
    202                 createBluetoothAlternateCarrierRecord(false)
    203         };
    204 
    205         NdefMessage nestedMessage = new NdefMessage(createCollisionRecord(), messages);
    206 
    207         byte[] nestedPayload = nestedMessage.toByteArray();
    208 
    209         ByteBuffer payload = ByteBuffer.allocate(nestedPayload.length + 1);
    210         payload.put((byte) 0x12);  // connection handover v1.2
    211         payload.put(nestedMessage.toByteArray());
    212 
    213         byte[] payloadBytes = new byte[payload.position()];
    214         payload.position(0);
    215         payload.get(payloadBytes);
    216         return new NdefRecord(NdefRecord.TNF_WELL_KNOWN, NdefRecord.RTD_HANDOVER_REQUEST, null,
    217                 payloadBytes);
    218     }
    219 
    220     /**
    221      * Returns null if message is not a Handover Request,
    222      * returns the IncomingHandoverData (Hs + parsed data) if it is.
    223      */
    224     public IncomingHandoverData getIncomingHandoverData(NdefMessage handoverRequest) {
    225         if (handoverRequest == null) return null;
    226         if (mBluetoothAdapter == null) return null;
    227 
    228         if (DBG) Log.d(TAG, "getIncomingHandoverData():" + handoverRequest.toString());
    229 
    230         NdefRecord handoverRequestRecord = handoverRequest.getRecords()[0];
    231         if (handoverRequestRecord.getTnf() != NdefRecord.TNF_WELL_KNOWN) {
    232             return null;
    233         }
    234 
    235         if (!Arrays.equals(handoverRequestRecord.getType(), NdefRecord.RTD_HANDOVER_REQUEST)) {
    236             return null;
    237         }
    238 
    239         // we have a handover request, look for BT OOB record
    240         BluetoothHandoverData bluetoothData = null;
    241         for (NdefRecord dataRecord : handoverRequest.getRecords()) {
    242             if (dataRecord.getTnf() == NdefRecord.TNF_MIME_MEDIA) {
    243                 if (Arrays.equals(dataRecord.getType(), TYPE_BT_OOB)) {
    244                     bluetoothData = parseBtOob(ByteBuffer.wrap(dataRecord.getPayload()));
    245                 }
    246             }
    247         }
    248 
    249         NdefMessage hs = tryBluetoothHandoverRequest(bluetoothData);
    250         if (hs != null) {
    251             return new IncomingHandoverData(hs, bluetoothData);
    252         }
    253 
    254         return null;
    255     }
    256 
    257     public BluetoothHandoverData getOutgoingHandoverData(NdefMessage handoverSelect) {
    258         return parseBluetooth(handoverSelect);
    259     }
    260 
    261     private NdefMessage tryBluetoothHandoverRequest(BluetoothHandoverData bluetoothData) {
    262         NdefMessage selectMessage = null;
    263         if (bluetoothData != null) {
    264             // Note: there could be a race where we conclude
    265             // that Bluetooth is already enabled, and shortly
    266             // after the user turns it off. That will cause
    267             // the transfer to fail, but there's nothing
    268             // much we can do about it anyway. It shouldn't
    269             // be common for the user to be changing BT settings
    270             // while waiting to receive a picture.
    271             boolean bluetoothActivating = !mBluetoothAdapter.isEnabled();
    272 
    273             // return BT OOB record so they can perform handover
    274             selectMessage = (createBluetoothHandoverSelectMessage(bluetoothActivating));
    275             if (DBG) Log.d(TAG, "Waiting for incoming transfer, [" +
    276                     bluetoothData.device.getAddress() + "]->[" + mLocalBluetoothAddress + "]");
    277         }
    278 
    279         return selectMessage;
    280     }
    281 
    282 
    283 
    284     boolean isCarrierActivating(NdefRecord handoverRec, byte[] carrierId) {
    285         byte[] payload = handoverRec.getPayload();
    286         if (payload == null || payload.length <= 1) return false;
    287         // Skip version
    288         byte[] payloadNdef = new byte[payload.length - 1];
    289         System.arraycopy(payload, 1, payloadNdef, 0, payload.length - 1);
    290         NdefMessage msg;
    291         try {
    292             msg = new NdefMessage(payloadNdef);
    293         } catch (FormatException e) {
    294             return false;
    295         }
    296 
    297         for (NdefRecord alt : msg.getRecords()) {
    298             byte[] acPayload = alt.getPayload();
    299             if (acPayload != null) {
    300                 ByteBuffer buf = ByteBuffer.wrap(acPayload);
    301                 int cps = buf.get() & 0x03; // Carrier Power State is in lower 2 bits
    302                 int carrierRefLength = buf.get() & 0xFF;
    303                 if (carrierRefLength != carrierId.length) return false;
    304 
    305                 byte[] carrierRefId = new byte[carrierRefLength];
    306                 buf.get(carrierRefId);
    307                 if (Arrays.equals(carrierRefId, carrierId)) {
    308                     // Found match, returning whether power state is activating
    309                     return (cps == CARRIER_POWER_STATE_ACTIVATING);
    310                 }
    311             }
    312         }
    313 
    314         return true;
    315     }
    316 
    317     BluetoothHandoverData parseBluetoothHandoverSelect(NdefMessage m) {
    318         // TODO we could parse this a lot more strictly; right now
    319         // we just search for a BT OOB record, and try to cross-reference
    320         // the carrier state inside the 'hs' payload.
    321         for (NdefRecord oob : m.getRecords()) {
    322             if (oob.getTnf() == NdefRecord.TNF_MIME_MEDIA &&
    323                     Arrays.equals(oob.getType(), TYPE_BT_OOB)) {
    324                 BluetoothHandoverData data = parseBtOob(ByteBuffer.wrap(oob.getPayload()));
    325                 if (data != null && isCarrierActivating(m.getRecords()[0], oob.getId())) {
    326                     data.carrierActivating = true;
    327                 }
    328                 return data;
    329             }
    330 
    331             if (oob.getTnf() == NdefRecord.TNF_MIME_MEDIA &&
    332                     Arrays.equals(oob.getType(), TYPE_BLE_OOB)) {
    333                 return parseBleOob(ByteBuffer.wrap(oob.getPayload()));
    334             }
    335         }
    336 
    337         return null;
    338     }
    339 
    340     public BluetoothHandoverData parseBluetooth(NdefMessage m) {
    341         NdefRecord r = m.getRecords()[0];
    342         short tnf = r.getTnf();
    343         byte[] type = r.getType();
    344 
    345         // Check for BT OOB record
    346         if (r.getTnf() == NdefRecord.TNF_MIME_MEDIA && Arrays.equals(r.getType(), TYPE_BT_OOB)) {
    347             return parseBtOob(ByteBuffer.wrap(r.getPayload()));
    348         }
    349 
    350         // Check for BLE OOB record
    351         if (r.getTnf() == NdefRecord.TNF_MIME_MEDIA && Arrays.equals(r.getType(), TYPE_BLE_OOB)) {
    352             return parseBleOob(ByteBuffer.wrap(r.getPayload()));
    353         }
    354 
    355         // Check for Handover Select, followed by a BT OOB record
    356         if (tnf == NdefRecord.TNF_WELL_KNOWN &&
    357                 Arrays.equals(type, NdefRecord.RTD_HANDOVER_SELECT)) {
    358             return parseBluetoothHandoverSelect(m);
    359         }
    360 
    361         // Check for Nokia BT record, found on some Nokia BH-505 Headsets
    362         if (tnf == NdefRecord.TNF_EXTERNAL_TYPE && Arrays.equals(type, TYPE_NOKIA)) {
    363             return parseNokia(ByteBuffer.wrap(r.getPayload()));
    364         }
    365 
    366         return null;
    367     }
    368 
    369     BluetoothHandoverData parseNokia(ByteBuffer payload) {
    370         BluetoothHandoverData result = new BluetoothHandoverData();
    371         result.valid = false;
    372 
    373         try {
    374             payload.position(1);
    375             byte[] address = new byte[6];
    376             payload.get(address);
    377             result.device = mBluetoothAdapter.getRemoteDevice(address);
    378             result.valid = true;
    379             payload.position(14);
    380             int nameLength = payload.get();
    381             byte[] nameBytes = new byte[nameLength];
    382             payload.get(nameBytes);
    383             result.name = new String(nameBytes, StandardCharsets.UTF_8);
    384         } catch (IllegalArgumentException e) {
    385             Log.i(TAG, "nokia: invalid BT address");
    386         } catch (BufferUnderflowException e) {
    387             Log.i(TAG, "nokia: payload shorter than expected");
    388         }
    389         if (result.valid && result.name == null) result.name = "";
    390         return result;
    391     }
    392 
    393     BluetoothHandoverData parseBtOob(ByteBuffer payload) {
    394         BluetoothHandoverData result = new BluetoothHandoverData();
    395         result.valid = false;
    396 
    397         try {
    398             payload.position(2); // length
    399             byte[] address = parseMacFromBluetoothRecord(payload);
    400             result.device = mBluetoothAdapter.getRemoteDevice(address);
    401             result.valid = true;
    402 
    403             while (payload.remaining() > 0) {
    404                 boolean success = false;
    405                 byte[] nameBytes;
    406                 int len = payload.get();
    407                 int type = payload.get();
    408                 switch (type) {
    409                     case BT_HANDOVER_TYPE_SHORT_LOCAL_NAME:
    410                         nameBytes = new byte[len - 1];
    411                         payload.get(nameBytes);
    412                         result.name = new String(nameBytes, StandardCharsets.UTF_8);
    413                         success = true;
    414                         break;
    415                     case BT_HANDOVER_TYPE_LONG_LOCAL_NAME:
    416                         if (result.name != null) break;  // prefer short name
    417                         nameBytes = new byte[len - 1];
    418                         payload.get(nameBytes);
    419                         result.name = new String(nameBytes, StandardCharsets.UTF_8);
    420                         success = true;
    421                         break;
    422                     case BT_HANDOVER_TYPE_16_BIT_UUIDS_PARTIAL:
    423                     case BT_HANDOVER_TYPE_16_BIT_UUIDS_COMPLETE:
    424                     case BT_HANDOVER_TYPE_32_BIT_UUIDS_PARTIAL:
    425                     case BT_HANDOVER_TYPE_32_BIT_UUIDS_COMPLETE:
    426                     case BT_HANDOVER_TYPE_128_BIT_UUIDS_PARTIAL:
    427                     case BT_HANDOVER_TYPE_128_BIT_UUIDS_COMPLETE:
    428                         result.uuids = parseUuidFromBluetoothRecord(payload, type, len - 1);
    429                         if (result.uuids != null) {
    430                             success = true;
    431                         }
    432                         break;
    433                     case BT_HANDOVER_TYPE_CLASS_OF_DEVICE:
    434                         if (len - 1 != CLASS_OF_DEVICE_SIZE) {
    435                             Log.i(TAG, "BT OOB: invalid size of Class of Device, should be " +
    436                                   CLASS_OF_DEVICE_SIZE + " bytes.");
    437                             break;
    438                         }
    439                         result.btClass = parseBluetoothClassFromBluetoothRecord(payload);
    440                         success = true;
    441                         break;
    442                     default:
    443                         break;
    444                 }
    445                 if (!success) {
    446                     payload.position(payload.position() + len - 1);
    447                 }
    448             }
    449         } catch (IllegalArgumentException e) {
    450             Log.i(TAG, "BT OOB: invalid BT address");
    451         } catch (BufferUnderflowException e) {
    452             Log.i(TAG, "BT OOB: payload shorter than expected");
    453         }
    454         if (result.valid && result.name == null) result.name = "";
    455         return result;
    456     }
    457 
    458     BluetoothHandoverData parseBleOob(ByteBuffer payload) {
    459         BluetoothHandoverData result = new BluetoothHandoverData();
    460         result.valid = false;
    461         result.transport = BluetoothDevice.TRANSPORT_LE;
    462 
    463         try {
    464 
    465             while (payload.remaining() > 0) {
    466                 int len = payload.get();
    467                 int type = payload.get();
    468                 switch (type) {
    469                     case BT_HANDOVER_TYPE_MAC: // mac address
    470 
    471                         int startpos = payload.position();
    472                         byte[] bdaddr = new byte[7]; // 6 bytes for mac, 1 for addres type
    473                         payload.get(bdaddr);
    474                         if (result.oobData == null)
    475                             result.oobData = new OobData();
    476                         result.oobData.setLeBluetoothDeviceAddress(bdaddr);
    477                         payload.position(startpos);
    478 
    479                         byte[] address = parseMacFromBluetoothRecord(payload);
    480                         payload.position(payload.position() + 1); // advance over random byte
    481                         result.device = mBluetoothAdapter.getRemoteDevice(address);
    482                         result.valid = true;
    483                         break;
    484                     case BT_HANDOVER_TYPE_LE_ROLE:
    485                         byte role = payload.get();
    486                         if (role == BT_HANDOVER_LE_ROLE_CENTRAL_ONLY) {
    487                             // only central role supported, can't pair
    488                             result.valid = false;
    489                             return result;
    490                         }
    491                         break;
    492                     case BT_HANDOVER_TYPE_LONG_LOCAL_NAME:
    493                         byte[] nameBytes = new byte[len - 1];
    494                         payload.get(nameBytes);
    495                         result.name = new String(nameBytes, StandardCharsets.UTF_8);
    496                         break;
    497                     case BT_HANDOVER_TYPE_SECURITY_MANAGER_TK:
    498                         if (len-1 != SECURITY_MANAGER_TK_SIZE) {
    499                             Log.i(TAG, "BT OOB: invalid size of SM TK, should be " +
    500                                   SECURITY_MANAGER_TK_SIZE + " bytes.");
    501                             break;
    502                         }
    503 
    504                         byte[] securityManagerTK = new byte[len - 1];
    505                         payload.get(securityManagerTK);
    506 
    507                         if (result.oobData == null)
    508                             result.oobData = new OobData();
    509                         result.oobData.setSecurityManagerTk(securityManagerTK);
    510                         break;
    511 
    512                     case BT_HANDOVER_TYPE_LE_SC_CONFIRMATION:
    513                         if (len - 1 != SECURITY_MANAGER_LE_SC_C_SIZE) {
    514                             Log.i(TAG, "BT OOB: invalid size of LE SC Confirmation, should be " +
    515                                   SECURITY_MANAGER_LE_SC_C_SIZE + " bytes.");
    516                             break;
    517                         }
    518 
    519                         byte[] leScC = new byte[len - 1];
    520                         payload.get(leScC);
    521 
    522                         if (result.oobData == null)
    523                             result.oobData = new OobData();
    524                         result.oobData.setLeSecureConnectionsConfirmation(leScC);
    525                         break;
    526 
    527                     case BT_HANDOVER_TYPE_LE_SC_RANDOM:
    528                         if (len-1 != SECURITY_MANAGER_LE_SC_R_SIZE) {
    529                             Log.i(TAG, "BT OOB: invalid size of LE SC Random, should be " +
    530                                   SECURITY_MANAGER_LE_SC_R_SIZE + " bytes.");
    531                             break;
    532                         }
    533 
    534                         byte[] leScR = new byte[len - 1];
    535                         payload.get(leScR);
    536 
    537                         if (result.oobData == null)
    538                             result.oobData = new OobData();
    539                         result.oobData.setLeSecureConnectionsRandom(leScR);
    540                         break;
    541 
    542                     default:
    543                         payload.position(payload.position() + len - 1);
    544                         break;
    545                 }
    546             }
    547         } catch (IllegalArgumentException e) {
    548             Log.i(TAG, "BLE OOB: error parsing OOB data", e);
    549         } catch (BufferUnderflowException e) {
    550             Log.i(TAG, "BT OOB: payload shorter than expected");
    551         }
    552         if (result.valid && result.name == null) result.name = "";
    553         return result;
    554     }
    555 
    556     private byte[] parseMacFromBluetoothRecord(ByteBuffer payload) {
    557         byte[] address = new byte[6];
    558         payload.get(address);
    559         // ByteBuffer.order(LITTLE_ENDIAN) doesn't work for
    560         // ByteBuffer.get(byte[]), so manually swap order
    561         for (int i = 0; i < 3; i++) {
    562             byte temp = address[i];
    563             address[i] = address[5 - i];
    564             address[5 - i] = temp;
    565         }
    566         return address;
    567     }
    568 
    569     static byte[] addressToReverseBytes(String address) {
    570         if (address == null) {
    571             Log.w(TAG, "BT address is null");
    572             return null;
    573         }
    574         String[] split = address.split(":");
    575         if (split.length < 6) {
    576             Log.w(TAG, "BT address " + address + " is invalid");
    577             return null;
    578         }
    579         byte[] result = new byte[split.length];
    580 
    581         for (int i = 0; i < split.length; i++) {
    582             // need to parse as int because parseByte() expects a signed byte
    583             result[split.length - 1 - i] = (byte)Integer.parseInt(split[i], 16);
    584         }
    585 
    586         return result;
    587     }
    588 
    589     private ParcelUuid[] parseUuidFromBluetoothRecord(ByteBuffer payload, int type, int len) {
    590         int uuidSize;
    591         switch (type) {
    592             case BT_HANDOVER_TYPE_16_BIT_UUIDS_PARTIAL:
    593             case BT_HANDOVER_TYPE_16_BIT_UUIDS_COMPLETE:
    594                 uuidSize = BluetoothUuid.UUID_BYTES_16_BIT;
    595                 break;
    596             case BT_HANDOVER_TYPE_32_BIT_UUIDS_PARTIAL:
    597             case BT_HANDOVER_TYPE_32_BIT_UUIDS_COMPLETE:
    598                 uuidSize = BluetoothUuid.UUID_BYTES_32_BIT;
    599                 break;
    600             case BT_HANDOVER_TYPE_128_BIT_UUIDS_PARTIAL:
    601             case BT_HANDOVER_TYPE_128_BIT_UUIDS_COMPLETE:
    602                 uuidSize = BluetoothUuid.UUID_BYTES_128_BIT;
    603                 break;
    604             default:
    605                 Log.i(TAG, "BT OOB: invalid size of UUID");
    606                 return null;
    607         }
    608 
    609         if (len == 0 || len % uuidSize != 0) {
    610             Log.i(TAG, "BT OOB: invalid size of UUIDs, should be multiples of UUID bytes length");
    611             return null;
    612         }
    613 
    614         int num = len / uuidSize;
    615         ParcelUuid[] uuids = new ParcelUuid[num];
    616         byte[] data = new byte[uuidSize];
    617         for (int i = 0; i < num; i++) {
    618             payload.get(data);
    619             uuids[i] = BluetoothUuid.parseUuidFrom(data);
    620         }
    621         return uuids;
    622     }
    623 
    624     private BluetoothClass parseBluetoothClassFromBluetoothRecord(ByteBuffer payload) {
    625         byte[] btClass = new byte[CLASS_OF_DEVICE_SIZE];
    626         payload.get(btClass);
    627 
    628         ByteBuffer buffer = ByteBuffer.allocate(Integer.BYTES);
    629         buffer.put(btClass);
    630         buffer.order(ByteOrder.LITTLE_ENDIAN);
    631 
    632         return new BluetoothClass(buffer.getInt(0));
    633     }
    634 }
    635