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      1 /*
      2  * Copyright (C) 2006 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.internal.telephony.gsm;
     18 
     19 /**
     20  * SIM Tag-Length-Value record
     21  * TS 102 223 Annex C
     22  *
     23  * {@hide}
     24  *
     25  */
     26 public class SimTlv
     27 {
     28     //***** Private Instance Variables
     29 
     30     byte mRecord[];
     31     int mTlvOffset;
     32     int mTlvLength;
     33     int mCurOffset;
     34     int mCurDataOffset;
     35     int mCurDataLength;
     36     boolean mHasValidTlvObject;
     37 
     38     public SimTlv(byte[] record, int offset, int length) {
     39         mRecord = record;
     40 
     41         mTlvOffset = offset;
     42         mTlvLength = length;
     43         mCurOffset = offset;
     44 
     45         mHasValidTlvObject = parseCurrentTlvObject();
     46     }
     47 
     48     public boolean nextObject() {
     49         if (!mHasValidTlvObject) return false;
     50         mCurOffset = mCurDataOffset + mCurDataLength;
     51         mHasValidTlvObject = parseCurrentTlvObject();
     52         return mHasValidTlvObject;
     53     }
     54 
     55     public boolean isValidObject() {
     56         return mHasValidTlvObject;
     57     }
     58 
     59     /**
     60      * Returns the tag for the current TLV object
     61      * Return 0 if !isValidObject()
     62      * 0 and 0xff are invalid tag values
     63      * valid tags range from 1 - 0xfe
     64      */
     65     public int getTag() {
     66         if (!mHasValidTlvObject) return 0;
     67         return mRecord[mCurOffset] & 0xff;
     68     }
     69 
     70     /**
     71      * Returns data associated with current TLV object
     72      * returns null if !isValidObject()
     73      */
     74 
     75     public byte[] getData() {
     76         if (!mHasValidTlvObject) return null;
     77 
     78         byte[] ret = new byte[mCurDataLength];
     79         System.arraycopy(mRecord, mCurDataOffset, ret, 0, mCurDataLength);
     80         return ret;
     81     }
     82 
     83     /**
     84      * Updates curDataLength and curDataOffset
     85      * @return false on invalid record, true on valid record
     86      */
     87 
     88     private boolean parseCurrentTlvObject() {
     89         // 0x00 and 0xff are invalid tag values
     90 
     91         try {
     92             if (mRecord[mCurOffset] == 0 || (mRecord[mCurOffset] & 0xff) == 0xff) {
     93                 return false;
     94             }
     95 
     96             if ((mRecord[mCurOffset + 1] & 0xff) < 0x80) {
     97                 // one byte length 0 - 0x7f
     98                 mCurDataLength = mRecord[mCurOffset + 1] & 0xff;
     99                 mCurDataOffset = mCurOffset + 2;
    100             } else if ((mRecord[mCurOffset + 1] & 0xff) == 0x81) {
    101                 // two byte length 0x80 - 0xff
    102                 mCurDataLength = mRecord[mCurOffset + 2] & 0xff;
    103                 mCurDataOffset = mCurOffset + 3;
    104             } else {
    105                 return false;
    106             }
    107         } catch (ArrayIndexOutOfBoundsException ex) {
    108             return false;
    109         }
    110 
    111         if (mCurDataLength + mCurDataOffset > mTlvOffset + mTlvLength) {
    112             return false;
    113         }
    114 
    115         return true;
    116     }
    117 
    118 }
    119