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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.cat;
     18 
     19 import java.util.List;
     20 
     21 /**
     22  * Class for representing BER-TLV objects.
     23  *
     24  * @see "ETSI TS 102 223 Annex C" for more information.
     25  *
     26  * {@hide}
     27  */
     28 class BerTlv {
     29     private int mTag = BER_UNKNOWN_TAG;
     30     private List<ComprehensionTlv> mCompTlvs = null;
     31 
     32     public static final int BER_UNKNOWN_TAG             = 0x00;
     33     public static final int BER_PROACTIVE_COMMAND_TAG   = 0xd0;
     34     public static final int BER_MENU_SELECTION_TAG      = 0xd3;
     35     public static final int BER_EVENT_DOWNLOAD_TAG      = 0xd6;
     36 
     37     private BerTlv(int tag, List<ComprehensionTlv> ctlvs) {
     38         mTag = tag;
     39         mCompTlvs = ctlvs;
     40     }
     41 
     42     /**
     43      * Gets a list of ComprehensionTlv objects contained in this BER-TLV object.
     44      *
     45      * @return A list of COMPREHENSION-TLV object
     46      */
     47     public List<ComprehensionTlv> getComprehensionTlvs() {
     48         return mCompTlvs;
     49     }
     50 
     51     /**
     52      * Gets a tag id of the BER-TLV object.
     53      *
     54      * @return A tag integer.
     55      */
     56     public int getTag() {
     57         return mTag;
     58     }
     59 
     60     /**
     61      * Decodes a BER-TLV object from a byte array.
     62      *
     63      * @param data A byte array to decode from
     64      * @return A BER-TLV object decoded
     65      * @throws ResultException
     66      */
     67     public static BerTlv decode(byte[] data) throws ResultException {
     68         int curIndex = 0;
     69         int endIndex = data.length;
     70         int tag, length = 0;
     71 
     72         try {
     73             /* tag */
     74             tag = data[curIndex++] & 0xff;
     75             if (tag == BER_PROACTIVE_COMMAND_TAG) {
     76                 /* length */
     77                 int temp = data[curIndex++] & 0xff;
     78                 if (temp < 0x80) {
     79                     length = temp;
     80                 } else if (temp == 0x81) {
     81                     temp = data[curIndex++] & 0xff;
     82                     if (temp < 0x80) {
     83                         throw new ResultException(
     84                                 ResultCode.CMD_DATA_NOT_UNDERSTOOD,
     85                                 "length < 0x80 length=" + Integer.toHexString(length) +
     86                                 " curIndex=" + curIndex + " endIndex=" + endIndex);
     87 
     88                     }
     89                     length = temp;
     90                 } else {
     91                     throw new ResultException(
     92                             ResultCode.CMD_DATA_NOT_UNDERSTOOD,
     93                             "Expected first byte to be length or a length tag and < 0x81" +
     94                             " byte= " + Integer.toHexString(temp) + " curIndex=" + curIndex +
     95                             " endIndex=" + endIndex);
     96                 }
     97             } else {
     98                 if (ComprehensionTlvTag.COMMAND_DETAILS.value() == (tag & ~0x80)) {
     99                     tag = BER_UNKNOWN_TAG;
    100                     curIndex = 0;
    101                 }
    102             }
    103         } catch (IndexOutOfBoundsException e) {
    104             throw new ResultException(ResultCode.REQUIRED_VALUES_MISSING,
    105                     "IndexOutOfBoundsException " +
    106                     " curIndex=" + curIndex + " endIndex=" + endIndex);
    107         } catch (ResultException e) {
    108             throw new ResultException(ResultCode.CMD_DATA_NOT_UNDERSTOOD, e.explanation());
    109         }
    110 
    111         /* COMPREHENSION-TLVs */
    112         if (endIndex - curIndex < length) {
    113             throw new ResultException(ResultCode.CMD_DATA_NOT_UNDERSTOOD,
    114                     "Command had extra data endIndex=" + endIndex + " curIndex=" + curIndex +
    115                     " length=" + length);
    116         }
    117 
    118         List<ComprehensionTlv> ctlvs = ComprehensionTlv.decodeMany(data,
    119                 curIndex);
    120 
    121         return new BerTlv(tag, ctlvs);
    122     }
    123 }
    124