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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 import com.android.server.wifi.ByteBufferReader;
     21 import com.android.server.wifi.hotspot2.anqp.eap.EAPMethod;
     22 
     23 import java.net.ProtocolException;
     24 import java.nio.BufferUnderflowException;
     25 import java.nio.ByteBuffer;
     26 import java.nio.ByteOrder;
     27 import java.nio.charset.StandardCharsets;
     28 import java.util.ArrayList;
     29 import java.util.Arrays;
     30 import java.util.Collections;
     31 import java.util.List;
     32 
     33 /**
     34  * The NAI Realm Data ANQP sub-element, IEEE802.11-2012 section 8.4.4.10 figure 8-418.
     35  *
     36  * Format:
     37  * | Length | Encoding | NAIRealm Length | NAIRealm | EAPMethod Count | EAPMethod #1 (optional) |
     38  *     2         1               1         variable          1                  variable
     39  */
     40 public class NAIRealmData {
     41     /**
     42      * Mask for determining NAI Realm String encoding type.
     43      */
     44     @VisibleForTesting
     45     public static final int NAI_ENCODING_UTF8_MASK = 0x1;
     46 
     47     @VisibleForTesting
     48     public static final String NAI_REALM_STRING_SEPARATOR = ";";
     49 
     50     private final List<String> mRealms;
     51     private final List<EAPMethod> mEAPMethods;
     52 
     53     @VisibleForTesting
     54     public NAIRealmData(List<String> realms, List<EAPMethod> eapMethods) {
     55         mRealms = realms;
     56         mEAPMethods = eapMethods;
     57     }
     58 
     59     /**
     60      * Parse a NAIRealmData from the given buffer.
     61      *
     62      * @param payload The byte buffer to read from
     63      * @return {@link NAIRealmElement}
     64      * @throws BufferUnderflowException
     65      * @throws ProtocolException
     66      */
     67     public static NAIRealmData parse(ByteBuffer payload) throws ProtocolException {
     68         // Read and verify the length field.
     69         int length = (int) ByteBufferReader.readInteger(payload, ByteOrder.LITTLE_ENDIAN, 2)
     70                 & 0xFFFF;
     71         if (length > payload.remaining()) {
     72             throw new ProtocolException("Invalid data length: " + length);
     73         }
     74 
     75         // Read the encoding field.
     76         boolean utf8 = (payload.get() & NAI_ENCODING_UTF8_MASK) != 0;
     77 
     78         // Read the realm string.
     79         String realm = ByteBufferReader.readStringWithByteLength(
     80                 payload, utf8 ? StandardCharsets.UTF_8 : StandardCharsets.US_ASCII);
     81         List<String> realmList = Arrays.asList(realm.split(NAI_REALM_STRING_SEPARATOR));
     82 
     83         // Read the EAP methods.
     84         int methodCount = payload.get() & 0xFF;
     85         List<EAPMethod> eapMethodList = new ArrayList<>();
     86         while (methodCount > 0) {
     87             eapMethodList.add(EAPMethod.parse(payload));
     88             methodCount--;
     89         }
     90         return new NAIRealmData(realmList, eapMethodList);
     91     }
     92 
     93     public List<String> getRealms() {
     94         return Collections.unmodifiableList(mRealms);
     95     }
     96 
     97     public List<EAPMethod> getEAPMethods() {
     98         return Collections.unmodifiableList(mEAPMethods);
     99     }
    100 
    101     @Override
    102     public boolean equals(Object thatObject) {
    103         if (this == thatObject) {
    104             return true;
    105         }
    106         if (!(thatObject instanceof NAIRealmData)) {
    107             return false;
    108         }
    109         NAIRealmData that = (NAIRealmData) thatObject;
    110         return mRealms.equals(that.mRealms) && mEAPMethods.equals(that.mEAPMethods);
    111     }
    112 
    113     @Override
    114     public int hashCode() {
    115         return mRealms.hashCode() * 31 + mEAPMethods.hashCode();
    116     }
    117 
    118     @Override
    119     public String toString() {
    120         return "NAIRealmElement{mRealms=" + mRealms + " mEAPMethods=" + mEAPMethods + "}";
    121     }
    122 }
    123