Android Open Source - ubihelper Dns Server

From Project

Back to project page ubihelper.
License

The source code is released under:
GNU General Public License
If you think the Android project ubihelper listed in this page is inappropriate, such as containing malicious code/tools or violating the copyright, please email info at java2s dot com, thanks.
Java Source Code

/**
 * Copyright (c) 2012 The University of Nottingham
 * /* w  w  w. ja v a  2  s .  c  o m*/
 * This file is part of ubihelper
 *
 *  ubihelper is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  ubihelper is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with ubihelper. If not, see <http://www.gnu.org/licenses/>.
 *  
 *  @author Chris Greenhalgh (cmg@cs.nott.ac.uk), The University of Nottingham
 */

package uk.ac.horizon.ubihelper.dns;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.LinkedList;
import java.util.logging.Logger;

import uk.ac.horizon.ubihelper.dns.DnsProtocol.SrvData;

//import android.util.Log;

/** Embedded multicast DNS server
 * @author cmg
 *
 */
public class DnsServer extends Thread {
  //static final String TAG = "ubihelper-dnssvr";
  static Logger logger =  Logger.getLogger(DnsServer.class.getName());
  
  public static final String MDNS_ADDRESS = "224.0.0.251";
  public static final int MDNS_PORT = 5353;

  private static final int MDMS_PACKET_SIZE = 512;
  
  private MulticastSocket socket = null;
  private boolean closed = false;
  private LinkedList<DnsProtocol.RR> rrs = new LinkedList<DnsProtocol.RR>();
  private NetworkInterface networkInterface;

  public DnsServer() {
  }
  
  public synchronized void setNeworkInterface(NetworkInterface ni) {
    networkInterface = ni;
    if (socket!=null) {
      try {
        socket.leaveGroup(InetAddress.getByName(MDNS_ADDRESS));
      } catch (Exception e) {
        logger.warning("Unable to leaveGroup: "+e.getMessage());
      }
      try {
        socket.setNetworkInterface(networkInterface);
        socket.joinGroup(InetAddress.getByName(MDNS_ADDRESS));
      } catch (Exception e) {
        logger.warning("Unable to setNetworkInterface: "+e.getMessage());
      }
    }
  }
  public synchronized void add(DnsProtocol.RR r) {
    remove(r);
    rrs.add(r);
  }
  public synchronized void remove(DnsProtocol.RR r) {
    for (int i=0; i<rrs.size(); i++) {
      DnsProtocol.RR r2 = rrs.get(i);
      if (r2.name.equals(r.name) && r2.rclass==r.rclass && r2.type==r.type) {
        // remove/replace
        rrs.remove(i);
        i--;
      }
    }    
  }
  public synchronized void clear() {
    rrs.clear();
  }
  
  public synchronized boolean isRunning() {
    return socket!=null;
  }
  public synchronized void close() {
    closed = true;
    interrupt();
    closeInternal();    
  }
  private synchronized void closeInternal() {
    if (socket!=null) {
      try {
        socket.close();
      }
      catch (Exception e) {
        /* ignore */
      }
      socket = null;
    }
  }
  
  public void run() {
    while (true) {
      MulticastSocket s = null;
      synchronized (this) {
        if (closed)
          break;
        if (socket==null) {
          try {
            socket = new MulticastSocket(MDNS_PORT);
            //socket.setTimeToLive(1);
            socket.setReuseAddress(true);
            if (networkInterface!=null)              
              socket.setNetworkInterface(networkInterface);
            // join group?! certainly needed on windows
            socket.joinGroup(InetAddress.getByName(MDNS_ADDRESS));
            // leave unbound (0.0.0.0)?!
            //Log.d(TAG,"Opened multicast socket "+MDNS_ADDRESS+":"+MDNS_PORT);
            logger.info("Opened multicast socket "+MDNS_ADDRESS+":"+MDNS_PORT+" (network interface "+networkInterface+")");
          }
          catch (Exception e) {
            //Log.e(TAG,"Creating multicast socket on "+MDNS_PORT+": "+e.getMessage());
            logger.warning("Creating multicast socket on "+MDNS_PORT+": "+e.getMessage());
            closeInternal();
            try {
              // avoid racing...
              wait(1000);
            } catch (InterruptedException e1) {
              /* ignore */
            }
          }
        }
        // copy ref
        s = socket;
      }
      try {
        byte buf[] = new byte[MDMS_PACKET_SIZE];
        DatagramPacket p = new DatagramPacket(buf, buf.length);
        s.receive(p);
        //Log.d(TAG,"Received "+p.getLength()+" bytes from "+p.getAddress().getHostAddress()+":"+p.getPort());
        logger.info("Received "+p.getLength()+" bytes from "+p.getAddress().getHostAddress()+":"+p.getPort());
        DnsProtocol pp = new DnsProtocol();
        pp.bytes = p.getData();
        pp.len = p.getLength();
        pp.unmarshall();
        if (!pp.response && pp.queries.length>0) {
          // start response...
          DnsProtocol rpp = new DnsProtocol();
          rpp.queries = new DnsProtocol.Query[0];
          rpp.response = true;
          rpp.id = pp.id;
          LinkedList<DnsProtocol.RR> resprrs = new LinkedList<DnsProtocol.RR>();
          synchronized (this) {
            for (int i=0; i<pp.queries.length; i++) {
              DnsProtocol.Query q = pp.queries[i];
              for (DnsProtocol.RR r : rrs) {
                if (q.name.equals(r.name) && q.type==r.type && q.rclass==r.rclass) {
                  //Log.d(TAG,"Found matching RR: "+r);
                  logger.info("Found matching RR: "+r);
                  resprrs.add(r);
                }
              }
            }
          }
          if (resprrs.size()>0) {
            rpp.answers = resprrs.toArray(new DnsProtocol.RR[resprrs.size()]);
            rpp.marshall();
            DatagramPacket rp = new DatagramPacket(rpp.bytes, rpp.len, p.getAddress(), p.getPort());
            //Log.d(TAG,"Sending response "+rp.getLength()+" bytes to "+rp.getAddress().getHostAddress()+":"+rp.getPort());
            logger.info("Sending response "+rp.getLength()+" bytes to "+rp.getAddress().getHostAddress()+":"+rp.getPort());
            s.send(rp);
          }
          else {
            logger.info("Ignored query "+pp+" from "+p.getAddress().getHostAddress()+":"+p.getPort());
          }
        }
      }
      catch (Exception e) {
        //Log.d(TAG,"Error doing receive: "+e.getMessage());
        logger.warning("Error doing receive: "+e.getMessage());
      }
    }
    closeInternal();
  }
  
  /** test */
  public static void main(String args[]) {
    NetworkInterface ni = DnsClient.getFirstActiveInterface();
    DnsServer server = new DnsServer();
    server.setNeworkInterface(ni);
    DnsProtocol.RR r = new DnsProtocol.RR();
    r.name = "some.name.local";
    r.rclass = DnsProtocol.CLASS_IN;
    r.type = DnsProtocol.TYPE_A;
    r.rdata = new byte[4];
    r.rdata[0] = 0x1; r.rdata[1] = 0x2; r.rdata[2] = 0x3; r.rdata[3] = 0x4;
    server.add(r);
    r = new DnsProtocol.RR();
    r.name = "_ubihelper._tcp.local";
    r.rclass = DnsProtocol.CLASS_IN;
    r.type = DnsProtocol.TYPE_PTR;
    r.rdata = DnsProtocol.ptrToData("Some instance", DnsUtils.getServiceDiscoveryName());
    server.add(r);
    r = new DnsProtocol.RR();
    r.name = "_ubihelper._tcp.local";
    r.rclass = DnsProtocol.CLASS_IN;
    r.type = DnsProtocol.TYPE_SRV;
    SrvData srv = new SrvData(1, 1, 8180, "some.name.local");
    r.rdata = DnsProtocol.srvToData(srv);
    server.add(r);
    server.start();
  }
}
Java Source Code List
