Java tutorial
/* * Copyright (C) 2012 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 android.net.wifi.p2p.nsd; import android.annotation.UnsupportedAppUsage; import android.net.nsd.DnsSdTxtRecord; import android.os.Build; import android.text.TextUtils; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Locale; import java.util.Map; /** * A class for storing Bonjour service information that is advertised * over a Wi-Fi peer-to-peer setup. * * {@see android.net.wifi.p2p.WifiP2pManager#addLocalService} * {@see android.net.wifi.p2p.WifiP2pManager#removeLocalService} * {@see WifiP2pServiceInfo} * {@see WifiP2pUpnpServiceInfo} */ public class WifiP2pDnsSdServiceInfo extends WifiP2pServiceInfo { /** * Bonjour version 1. * @hide */ public static final int VERSION_1 = 0x01; /** * Pointer record. * @hide */ public static final int DNS_TYPE_PTR = 12; /** * Text record. * @hide */ public static final int DNS_TYPE_TXT = 16; /** * virtual memory packet. * see E.3 of the Wi-Fi Direct technical specification for the detail.<br> * Key: domain name Value: pointer address.<br> */ private final static Map<String, String> sVmPacket; static { sVmPacket = new HashMap<String, String>(); sVmPacket.put("_tcp.local.", "c00c"); sVmPacket.put("local.", "c011"); sVmPacket.put("_udp.local.", "c01c"); } /** * This constructor is only used in newInstance(). * * @param queryList */ private WifiP2pDnsSdServiceInfo(List<String> queryList) { super(queryList); } /** * Create a Bonjour service information object. * * @param instanceName instance name.<br> * e.g) "MyPrinter" * @param serviceType service type.<br> * e.g) "_ipp._tcp" * @param txtMap TXT record with key/value pair in a map confirming to format defined at * http://files.dns-sd.org/draft-cheshire-dnsext-dns-sd.txt * @return Bonjour service information object */ public static WifiP2pDnsSdServiceInfo newInstance(String instanceName, String serviceType, Map<String, String> txtMap) { if (TextUtils.isEmpty(instanceName) || TextUtils.isEmpty(serviceType)) { throw new IllegalArgumentException("instance name or service type cannot be empty"); } DnsSdTxtRecord txtRecord = new DnsSdTxtRecord(); if (txtMap != null) { for (String key : txtMap.keySet()) { txtRecord.set(key, txtMap.get(key)); } } ArrayList<String> queries = new ArrayList<String>(); queries.add(createPtrServiceQuery(instanceName, serviceType)); queries.add(createTxtServiceQuery(instanceName, serviceType, txtRecord)); return new WifiP2pDnsSdServiceInfo(queries); } /** * Create wpa_supplicant service query for PTR record. * * @param instanceName instance name.<br> * e.g) "MyPrinter" * @param serviceType service type.<br> * e.g) "_ipp._tcp" * @return wpa_supplicant service query. */ private static String createPtrServiceQuery(String instanceName, String serviceType) { StringBuffer sb = new StringBuffer(); sb.append("bonjour "); sb.append(createRequest(serviceType + ".local.", DNS_TYPE_PTR, VERSION_1)); sb.append(" "); byte[] data = instanceName.getBytes(); sb.append(String.format(Locale.US, "%02x", data.length)); sb.append(WifiP2pServiceInfo.bin2HexStr(data)); // This is the start point of this response. // Therefore, it indicates the request domain name. sb.append("c027"); return sb.toString(); } /** * Create wpa_supplicant service query for TXT record. * * @param instanceName instance name.<br> * e.g) "MyPrinter" * @param serviceType service type.<br> * e.g) "_ipp._tcp" * @param txtRecord TXT record.<br> * @return wpa_supplicant service query. */ private static String createTxtServiceQuery(String instanceName, String serviceType, DnsSdTxtRecord txtRecord) { StringBuffer sb = new StringBuffer(); sb.append("bonjour "); sb.append(createRequest((instanceName + "." + serviceType + ".local."), DNS_TYPE_TXT, VERSION_1)); sb.append(" "); byte[] rawData = txtRecord.getRawData(); if (rawData.length == 0) { sb.append("00"); } else { sb.append(bin2HexStr(rawData)); } return sb.toString(); } /** * Create bonjour service discovery request. * * @param dnsName dns name * @param dnsType dns type * @param version version number * @hide */ @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.P, trackingBug = 115609023) static String createRequest(String dnsName, int dnsType, int version) { StringBuffer sb = new StringBuffer(); /* * The request format is as follows. * ________________________________________________ * | Encoded and Compressed dns name (variable) | * ________________________________________________ * | Type (2) | Version (1) | */ if (dnsType == WifiP2pDnsSdServiceInfo.DNS_TYPE_TXT) { dnsName = dnsName.toLowerCase(Locale.ROOT); // TODO: is this right? } sb.append(compressDnsName(dnsName)); sb.append(String.format(Locale.US, "%04x", dnsType)); sb.append(String.format(Locale.US, "%02x", version)); return sb.toString(); } /** * Compress DNS data. * * see E.3 of the Wi-Fi Direct technical specification for the detail. * * @param dnsName dns name * @return compressed dns name */ private static String compressDnsName(String dnsName) { StringBuffer sb = new StringBuffer(); // The domain name is replaced with a pointer to a prior // occurrence of the same name in virtual memory packet. while (true) { String data = sVmPacket.get(dnsName); if (data != null) { sb.append(data); break; } int i = dnsName.indexOf('.'); if (i == -1) { if (dnsName.length() > 0) { sb.append(String.format(Locale.US, "%02x", dnsName.length())); sb.append(WifiP2pServiceInfo.bin2HexStr(dnsName.getBytes())); } // for a sequence of labels ending in a zero octet sb.append("00"); break; } String name = dnsName.substring(0, i); dnsName = dnsName.substring(i + 1); sb.append(String.format(Locale.US, "%02x", name.length())); sb.append(WifiP2pServiceInfo.bin2HexStr(name.getBytes())); } return sb.toString(); } }