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      1 /*
      2  * Copyright (C) 2016 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.server.wifi.hotspot2.anqp;
     18 
     19 import com.android.internal.annotations.VisibleForTesting;
     20 
     21 import java.net.ProtocolException;
     22 import java.nio.BufferUnderflowException;
     23 import java.nio.ByteBuffer;
     24 import java.util.ArrayList;
     25 import java.util.Collections;
     26 import java.util.List;
     27 
     28 
     29 /**
     30  * The 3GPP Cellular Network ANQP Element, IEEE802.11-2012 section 8.4.4.11.
     31  * The value is embedded in a Generic container User Data (GUD).
     32  * Refer to Annex A of 3GPP TS 24.234 version 11.3.0 for more info:
     33  * (http://www.etsi.org/deliver/etsi_ts/124200_124299/124234/11.03.00_60/ts_124234v110300p.pdf).
     34  *
     35  * Format:
     36  * | GUD Version | Length | IEI 1 | ... | IEI N|
     37  *        1           1    variable
     38  *
     39  */
     40 public class ThreeGPPNetworkElement extends ANQPElement {
     41     /**
     42      * The expected protocol version number of the Generic container User Data (GUD).
     43      */
     44     @VisibleForTesting
     45     public static final int GUD_VERSION_1 = 0;
     46 
     47     private final List<CellularNetwork> mNetworks;
     48 
     49     @VisibleForTesting
     50     public ThreeGPPNetworkElement(List<CellularNetwork> networks) {
     51         super(Constants.ANQPElementType.ANQP3GPPNetwork);
     52         mNetworks = networks;
     53     }
     54 
     55     /**
     56      * Parse a ThreeGPPNetworkElement from the given buffer.
     57      *
     58      * @param payload The byte buffer to read from
     59      * @return {@link ThreeGPPNetworkElement}
     60      * @throws BufferUnderflowException
     61      * @throws ProtocolException
     62      */
     63     public static ThreeGPPNetworkElement parse(ByteBuffer payload)
     64             throws ProtocolException {
     65         // Verify version.
     66         int gudVersion = payload.get() & 0xFF;
     67         if (gudVersion != GUD_VERSION_1) {
     68             throw new ProtocolException("Unsupported GUD version: " + gudVersion);
     69         }
     70 
     71         // Verify length.
     72         int length = payload.get() & 0xFF;
     73         if (length != payload.remaining()) {
     74             throw new ProtocolException("Mismatch length and buffer size: length=" + length
     75                     + " bufferSize=" + payload.remaining());
     76         }
     77 
     78         // Parse each IEI (Information Element Identity) content.
     79         List<CellularNetwork> networks = new ArrayList<>();
     80         while (payload.hasRemaining()) {
     81             CellularNetwork network = CellularNetwork.parse(payload);
     82             if (network != null) {
     83                 networks.add(network);
     84             }
     85         }
     86         return new ThreeGPPNetworkElement(networks);
     87     }
     88 
     89     public List<CellularNetwork> getNetworks() {
     90         return Collections.unmodifiableList(mNetworks);
     91     }
     92 
     93     @Override
     94     public boolean equals(Object thatObject) {
     95         if (this == thatObject) {
     96             return true;
     97         }
     98         if (!(thatObject instanceof ThreeGPPNetworkElement)) {
     99             return false;
    100         }
    101         ThreeGPPNetworkElement that = (ThreeGPPNetworkElement) thatObject;
    102         return mNetworks.equals(that.mNetworks);
    103 
    104     }
    105 
    106     @Override
    107     public int hashCode() {
    108         return mNetworks.hashCode();
    109     }
    110 
    111     @Override
    112     public String toString() {
    113         return "ThreeGPPNetwork{mNetworks=" + mNetworks + "}";
    114     }
    115 }
    116