content: /*
   * 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();
      }
  }
  