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
NAIRealmData(List<String> realms, List<EAPMethod> eapMethods)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      */
parse(ByteBuffer payload)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 
getRealms()93     public List<String> getRealms() {
94         return Collections.unmodifiableList(mRealms);
95     }
96 
getEAPMethods()97     public List<EAPMethod> getEAPMethods() {
98         return Collections.unmodifiableList(mEAPMethods);
99     }
100 
101     @Override
equals(Object thatObject)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
hashCode()114     public int hashCode() {
115         return mRealms.hashCode() * 31 + mEAPMethods.hashCode();
116     }
117 
118     @Override
toString()119     public String toString() {
120         return "NAIRealmElement{mRealms=" + mRealms + " mEAPMethods=" + mEAPMethods + "}";
121     }
122 }
123