Android Open Source - azilink Udp Engine

• Back to Hardware/usb  ↑

From Project

Back to project page azilink.

License

The source code is released under:

GNU General Public License

Java Source Code

/* AziLink: USB tethering for Android
 * Copyright (C) 2009 by James Perry/* w w  w . jav a 2 s .  co m*/
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) version 3 of the License.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.lfx.azilink.net;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.HashMap;
import java.util.Iterator;

import android.util.Log;

/**
 * Engine that holds all active UDP links
 * 
 * @author Jim Perry
 *
 */
public class UdpEngine {
  /**
   * Map of all connections, indexed by src/dest ip/port
   */
  HashMap< UdpKey, UdpDriver > mNat = new HashMap<UdpKey, UdpDriver>();
  /**
   * Pointer to the NAT engine
   */
  VpnNatEngine mEngine;
  
  UdpEngine( VpnNatEngine e ) {
    mEngine = e;
  }
  
  /**
   * Teardown a specific UDP connection
   * @param nt connection to remove
   */
  public void close(UdpDriver nt) {
    try {
      nt.mChannel.close();
    } catch (IOException e) {
    }
    mEngine.mTimers.killTimer(nt.mTimerKey,nt);
    mNat.remove( nt.mAddr );
  }  
  
  /**
   * Teardown all UDP connections
   */
  public void closeAll() {
    //if(VpnNatEngine.sLog) Log.v("AziLink", "Close ALL" );
    Iterator<UdpDriver> i = mNat.values().iterator();
    while( i.hasNext() ) {
      UdpDriver u = i.next();
      try {
        u.mChannel.close();
      } catch (IOException e) {
      }
      i.remove();      
    }
  }
  
  /**
   * Handle a new packet received from the VPN (dispatch to the UdpDriver)
   * @param d vpn packet
   */
  void readRawPacket( byte[] d ) {
    ByteBuffer bb = ByteBuffer.wrap( d );
    int headerLength = (((int) bb.get(0)) & 0x0F) * 4;
    
    int protocol = ((int) bb.get( 9 )) & 0xFF;
    boolean isIcmp = protocol == 1;
    
    if( d.length < headerLength + 8 ) {
      if(VpnNatEngine.sLog) Log.v("AziLink", "Packet under minimum UDP length" );
      return;
    }
    
    UdpPacket pkt;
    if( isIcmp ) {
      IcmpPacket ip = new IcmpPacket(d);
      if(ip.getType() != IcmpPacket.TYPE_ICMP_ECHO_REQUEST ||
          ip.getCode() != IcmpPacket.PROTO_ICMP_ECHO_REQUEST) return;
      if(VpnNatEngine.sLog) Log.v("AziLink","Translate ICMP -> UDP");
      UdpKey nk = new UdpKey();
      IcmpKey ik = ip.getAddresses();
      nk.mDestIp = ik.mSrcIp;
      nk.mSrcIp = ik.mDestIp;
      nk.mDestPort = ip.getSequence() ^ ip.getId();
      nk.mSrcPort = 7;
      pkt = new UdpPacket( nk );    // this will reverse the host/port
      pkt.setData(ip.mRaw.array(), ip.mPacketLength);
    } else {
      pkt = new UdpPacket( d );      
    }
    UdpKey nk = pkt.getAddresses();    
    
    UdpDriver te = mNat.get( nk );
    if( te == null ) {      
      try {
        te = new UdpDriver( mEngine, nk, pkt, isIcmp );
        mNat.put( te.mAddr, te );
        te.readRawPacket( pkt );
      } catch( IOException e ) {}      
    } else {
      te.readRawPacket( pkt );
    }
  }
}

Java Source Code List

• Back to Hardware/usb  ↑