1 /*
2  * Copyright (C) 2012 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 android.net.wifi.p2p.nsd;
18 
19 import android.compat.annotation.UnsupportedAppUsage;
20 import android.os.Build;
21 import android.text.TextUtils;
22 
23 import com.android.net.module.util.DnsSdTxtRecord;
24 
25 import java.util.ArrayList;
26 import java.util.HashMap;
27 import java.util.List;
28 import java.util.Locale;
29 import java.util.Map;
30 
31 /**
32  * A class for storing Bonjour service information that is advertised
33  * over a Wi-Fi peer-to-peer setup.
34  *
35  * {@see android.net.wifi.p2p.WifiP2pManager#addLocalService}
36  * {@see android.net.wifi.p2p.WifiP2pManager#removeLocalService}
37  * {@see WifiP2pServiceInfo}
38  * {@see WifiP2pUpnpServiceInfo}
39  */
40 public class WifiP2pDnsSdServiceInfo extends WifiP2pServiceInfo {
41 
42     /**
43      * Bonjour version 1.
44      * @hide
45      */
46     public static final int VERSION_1 = 0x01;
47 
48     /**
49      * Pointer record.
50      * @hide
51      */
52     public static final int DNS_TYPE_PTR = 12;
53 
54     /**
55      * Text record.
56      * @hide
57      */
58     public static final int DNS_TYPE_TXT = 16;
59 
60     /**
61      * virtual memory packet.
62      * see E.3 of the Wi-Fi Direct technical specification for the detail.<br>
63      * Key: domain name Value: pointer address.<br>
64      */
65     private final static Map<String, String> sVmPacket;
66 
67     static {
68         sVmPacket = new HashMap<String, String>();
69         sVmPacket.put("_tcp.local.", "c00c");
70         sVmPacket.put("local.", "c011");
71         sVmPacket.put("_udp.local.", "c01c");
72     }
73 
74     /**
75      * This constructor is only used in newInstance().
76      *
77      * @param queryList
78      */
WifiP2pDnsSdServiceInfo(List<String> queryList)79     private WifiP2pDnsSdServiceInfo(List<String> queryList) {
80         super(queryList);
81     }
82 
83     /**
84      * Create a Bonjour service information object.
85      *
86      * @param instanceName instance name.<br>
87      *  e.g) "MyPrinter"
88      * @param serviceType service type.<br>
89      *  e.g) "_ipp._tcp"
90      * @param txtMap TXT record with key/value pair in a map confirming to format defined at
91      * http://files.dns-sd.org/draft-cheshire-dnsext-dns-sd.txt
92      * @return Bonjour service information object
93      */
newInstance(String instanceName, String serviceType, Map<String, String> txtMap)94     public static WifiP2pDnsSdServiceInfo newInstance(String instanceName,
95             String serviceType, Map<String, String> txtMap) {
96         if (TextUtils.isEmpty(instanceName) || TextUtils.isEmpty(serviceType)) {
97             throw new IllegalArgumentException(
98                     "instance name or service type cannot be empty");
99         }
100 
101         DnsSdTxtRecord txtRecord = new DnsSdTxtRecord();
102         if (txtMap != null) {
103             for (String key : txtMap.keySet()) {
104                 txtRecord.set(key, txtMap.get(key));
105             }
106         }
107 
108         ArrayList<String> queries = new ArrayList<String>();
109         queries.add(createPtrServiceQuery(instanceName, serviceType));
110         queries.add(createTxtServiceQuery(instanceName, serviceType, txtRecord));
111 
112         return new WifiP2pDnsSdServiceInfo(queries);
113     }
114 
115     /**
116      * Create wpa_supplicant service query for PTR record.
117      *
118      * @param instanceName instance name.<br>
119      *  e.g) "MyPrinter"
120      * @param serviceType service type.<br>
121      *  e.g) "_ipp._tcp"
122      * @return wpa_supplicant service query.
123      */
createPtrServiceQuery(String instanceName, String serviceType)124     private static String createPtrServiceQuery(String instanceName,
125             String serviceType) {
126 
127         StringBuffer sb = new StringBuffer();
128         sb.append("bonjour ");
129         sb.append(createRequest(serviceType + ".local.", DNS_TYPE_PTR, VERSION_1));
130         sb.append(" ");
131 
132         byte[] data = instanceName.getBytes();
133         sb.append(String.format(Locale.US, "%02x", data.length));
134         sb.append(WifiP2pServiceInfo.bin2HexStr(data));
135         // This is the start point of this response.
136         // Therefore, it indicates the request domain name.
137         sb.append("c027");
138         return sb.toString();
139     }
140 
141     /**
142      * Create wpa_supplicant service query for TXT record.
143      *
144      * @param instanceName instance name.<br>
145      *  e.g) "MyPrinter"
146      * @param serviceType service type.<br>
147      *  e.g) "_ipp._tcp"
148      * @param txtRecord TXT record.<br>
149      * @return wpa_supplicant service query.
150      */
createTxtServiceQuery(String instanceName, String serviceType, DnsSdTxtRecord txtRecord)151     private static String createTxtServiceQuery(String instanceName,
152             String serviceType,
153             DnsSdTxtRecord txtRecord) {
154 
155 
156         StringBuffer sb = new StringBuffer();
157         sb.append("bonjour ");
158 
159         sb.append(createRequest((instanceName + "." + serviceType + ".local."),
160                 DNS_TYPE_TXT, VERSION_1));
161         sb.append(" ");
162         byte[] rawData = txtRecord.getRawData();
163         if (rawData.length == 0) {
164             sb.append("00");
165         } else {
166             sb.append(bin2HexStr(rawData));
167         }
168         return sb.toString();
169     }
170 
171     /**
172      * Create bonjour service discovery request.
173      *
174      * @param dnsName dns name
175      * @param dnsType dns type
176      * @param version version number
177      * @hide
178      */
179     @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023)
createRequest(String dnsName, int dnsType, int version)180     static String createRequest(String dnsName, int dnsType, int version) {
181         StringBuffer sb = new StringBuffer();
182 
183         /*
184          * The request format is as follows.
185          * ________________________________________________
186          * |  Encoded and Compressed dns name (variable)  |
187          * ________________________________________________
188          * |   Type (2)           | Version (1) |
189          */
190         if (dnsType == WifiP2pDnsSdServiceInfo.DNS_TYPE_TXT) {
191             dnsName = dnsName.toLowerCase(Locale.ROOT); // TODO: is this right?
192         }
193         sb.append(compressDnsName(dnsName));
194         sb.append(String.format(Locale.US, "%04x", dnsType));
195         sb.append(String.format(Locale.US, "%02x", version));
196 
197         return sb.toString();
198     }
199 
200     /**
201      * Compress DNS data.
202      *
203      * see E.3 of the Wi-Fi Direct technical specification for the detail.
204      *
205      * @param dnsName dns name
206      * @return compressed dns name
207      */
compressDnsName(String dnsName)208     private static String compressDnsName(String dnsName) {
209         StringBuffer sb = new StringBuffer();
210 
211         // The domain name is replaced with a pointer to a prior
212         // occurrence of the same name in virtual memory packet.
213         while (true) {
214             String data = sVmPacket.get(dnsName);
215             if (data != null) {
216                 sb.append(data);
217                 break;
218             }
219             int i = dnsName.indexOf('.');
220             if (i == -1) {
221                 if (dnsName.length() > 0) {
222                     sb.append(String.format(Locale.US, "%02x", dnsName.length()));
223                     sb.append(WifiP2pServiceInfo.bin2HexStr(dnsName.getBytes()));
224                 }
225                 // for a sequence of labels ending in a zero octet
226                 sb.append("00");
227                 break;
228             }
229 
230             String name = dnsName.substring(0, i);
231             dnsName = dnsName.substring(i + 1);
232             sb.append(String.format(Locale.US, "%02x", name.length()));
233             sb.append(WifiP2pServiceInfo.bin2HexStr(name.getBytes()));
234         }
235         return sb.toString();
236     }
237 }
238