Jxnet: Filtering The Traffic

package com.ardikars.test.jxnet;

import java.nio.ByteBuffer;

import com.ardikars.jxnet.BpfProgram;
import com.ardikars.jxnet.Jxnet;
import com.ardikars.jxnet.Pcap;
import com.ardikars.jxnet.PcapHandler;
import com.ardikars.jxnet.PcapPktHdr;
import com.ardikars.jxnet.PcapStat;

public class FilteringTheTraffic {

 public static void main(String[] args) {
  
  StringBuilder errbuf = new StringBuilder();
  String source = Jxnet.PcapLookupdev(errbuf);
  BpfProgram fp = new BpfProgram();
  String filter = "ip";
  int netmask = 0xffffff;
  PcapStat stat = new PcapStat();
  if(source == null) {
   System.err.println(errbuf.toString());
   return;
  }
  Pcap pcap = Jxnet.PcapOpenLive(source, 65535, 1, 2000, errbuf);
  if(pcap == null) {
   System.err.println(errbuf.toString());
   return;
  }
  if(Jxnet.PcapDatalink(pcap)!= 1) {
   System.out.println(source + " is not an Ethernet");
   Jxnet.PcapClose(pcap);
   return;
  }
  if(Jxnet.PcapCompile(pcap, fp, filter, 1, netmask) != 0) {
   System.err.println("Failed to compile bpf");
   Jxnet.PcapClose(pcap);
   return;
  }
  if(Jxnet.PcapSetFilter(pcap, fp) != 0) {
   System.err.println("Failed to set filter");
   Jxnet.PcapClose(pcap);
   return;
  }
  PcapHandler callback = new PcapHandler() {
   @Override
   public void nextPacket(String u, PcapPktHdr h, ByteBuffer b) {
    System.out.println(h);
    System.out.println(b);
   }
  };
  Jxnet.PcapLoop(pcap, 10, callback, null);
  if(Jxnet.PcapStat(pcap, stat) !=0 ) {
   System.out.println(Jxnet.PcapGetErr(pcap));
  } else {
   System.out.println("Number of packets received = " + stat.getPsRecv());
   System.out.println("Number of packets dropped = " + stat.getPsDrop());
   System.out.println("Drops by interface = " + stat.getPsIfdrop());
  }
  Jxnet.PcapClose(pcap);
  
 }

}