content: /*
   * Copyright (C) 2006 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 com.android.internal.telephony.cat;
  
  import java.util.List;
  
  /**
   * Class for representing BER-TLV objects.
   *
   * @see "ETSI TS 102 223 Annex C" for more information.
   *
   * {@hide}
   */
  class BerTlv {
      private int mTag = BER_UNKNOWN_TAG;
      private List<ComprehensionTlv> mCompTlvs = null;
      private boolean mLengthValid = true;
  
      public static final int BER_UNKNOWN_TAG             = 0x00;
      public static final int BER_PROACTIVE_COMMAND_TAG   = 0xd0;
      public static final int BER_MENU_SELECTION_TAG      = 0xd3;
      public static final int BER_EVENT_DOWNLOAD_TAG      = 0xd6;
  
      private BerTlv(int tag, List<ComprehensionTlv> ctlvs, boolean lengthValid) {
          mTag = tag;
          mCompTlvs = ctlvs;
          mLengthValid = lengthValid;
      }
  
      /**
       * Gets a list of ComprehensionTlv objects contained in this BER-TLV object.
       *
       * @return A list of COMPREHENSION-TLV object
       */
      public List<ComprehensionTlv> getComprehensionTlvs() {
          return mCompTlvs;
      }
  
      /**
       * Gets a tag id of the BER-TLV object.
       *
       * @return A tag integer.
       */
      public int getTag() {
          return mTag;
      }
  
      /**
       * Gets if the length of the BER-TLV object is valid
       *
       * @return if length valid
       */
       public boolean isLengthValid() {
           return mLengthValid;
       }
  
      /**
       * Decodes a BER-TLV object from a byte array.
       *
       * @param data A byte array to decode from
       * @return A BER-TLV object decoded
       * @throws ResultException
       */
      public static BerTlv decode(byte[] data) throws ResultException {
          int curIndex = 0;
          int endIndex = data.length;
          int tag, length = 0;
          boolean isLengthValid = true;
  
          try {
              /* tag */
              tag = data[curIndex++] & 0xff;
              if (tag == BER_PROACTIVE_COMMAND_TAG) {
                  /* length */
                  int temp = data[curIndex++] & 0xff;
                  if (temp < 0x80) {
                      length = temp;
                  } else if (temp == 0x81) {
                      temp = data[curIndex++] & 0xff;
                      if (temp < 0x80) {
                          throw new ResultException(
                                  ResultCode.CMD_DATA_NOT_UNDERSTOOD,
                                  "length < 0x80 length=" + Integer.toHexString(length) +
                                  " curIndex=" + curIndex + " endIndex=" + endIndex);
  
                      }
                      length = temp;
                  } else {
                      throw new ResultException(
                              ResultCode.CMD_DATA_NOT_UNDERSTOOD,
                              "Expected first byte to be length or a length tag and < 0x81" +
                              " byte= " + Integer.toHexString(temp) + " curIndex=" + curIndex +
                              " endIndex=" + endIndex);
                  }
              } else {
                  if (ComprehensionTlvTag.COMMAND_DETAILS.value() == (tag & ~0x80)) {
                      tag = BER_UNKNOWN_TAG;
                      curIndex = 0;
                  }
              }
          } catch (IndexOutOfBoundsException e) {
              throw new ResultException(ResultCode.REQUIRED_VALUES_MISSING,
                      "IndexOutOfBoundsException " +
                      " curIndex=" + curIndex + " endIndex=" + endIndex);
          } catch (ResultException e) {
              throw new ResultException(ResultCode.CMD_DATA_NOT_UNDERSTOOD, e.explanation());
          }
  
          /* COMPREHENSION-TLVs */
          if (endIndex - curIndex < length) {
              throw new ResultException(ResultCode.CMD_DATA_NOT_UNDERSTOOD,
                      "Command had extra data endIndex=" + endIndex + " curIndex=" + curIndex +
                      " length=" + length);
          }
  
          List<ComprehensionTlv> ctlvs = ComprehensionTlv.decodeMany(data,
                  curIndex);
  
          if (tag == BER_PROACTIVE_COMMAND_TAG) {
              int totalLength = 0;
              for (ComprehensionTlv item : ctlvs) {
                  int itemLength = item.getLength();
                  if (itemLength >= 0x80 && itemLength <= 0xFF) {
                      totalLength += itemLength + 3; //3: 'tag'(1 byte) and 'length'(2 bytes).
                  } else if (itemLength >= 0 && itemLength < 0x80) {
                      totalLength += itemLength + 2; //2: 'tag'(1 byte) and 'length'(1 byte).
                  } else {
                      isLengthValid = false;
                      break;
                  }
              }
  
              // According to 3gpp11.14, chapter 6.10.6 "Length errors",
  
              // If the total lengths of the SIMPLE-TLV data objects are not
              // consistent with the length given in the BER-TLV data object,
              // then the whole BER-TLV data object shall be rejected. The
              // result field in the TERMINAL RESPONSE shall have the error
              // condition "Command data not understood by ME".
              if (length != totalLength) {
                  isLengthValid = false;
              }
          }
  
          return new BerTlv(tag, ctlvs, isLengthValid);
      }
  }
  