null pointer exception with jpcap
class Thread1 extends Thread
{
public void run()
{
try
{
String[] devices=Jpcap.getDeviceList();
String val="";
for(int j=0;j<50;j++)
{
System.out.println(devices[j]);
val=val+devices[j];
}
Jpcap jpcap=Jpcap.openDevice(val,10000,false,20);
jpcap.loopPacket(-1,new PacketSniff());
}
catch(Exception e1)
{
pane1.showMessageDialog(f1,"Error occured");
}
}
//
A simple program to capture packets and display the drivers on clicking a button on the gui.A null pointer exception is raised when the device array is accessed(the array is not empty).
[684 byte] By [
java_blaa] at [2007-11-27 2:25:25]
# 3
here is the full class
On clicking "sniff" button in the main window control comes to this class..
--
import javax.swing.*;
import javax.swing.table.*;
import java.awt.event.*;
import java.awt.*;
import javax.swing.event.*;
import jpcap.*;
public class AllProtocols extends JFrame implements ActionListener
{
JButton bstart = new JButton("START SNIFF");
JButton bpause = new JButton("PAUSE SNIFF");
JButton bclose = new JButton("CLOSE");
DefaultTableModel model = new DefaultTableModel();
JTable table = new JTable(model);
JScrollPane pane=new JScrollPane();
Container con;
Thread1 th=new Thread1();
boolean SniffStatus = true;
String st;
JOptionPane pane1=new JOptionPane();
JFrame f1;
AllProtocols()
{
con = getContentPane();
pane=new JScrollPane(table);
f1=this;
JPanel p1=new JPanel(new FlowLayout());
p1.add(bstart);
p1.add(bpause);
p1.add(bclose);
con.add(p1,"South");
con.add(pane);
model.addColumn("SourceIP");
model.addColumn("DestinationIP");
model.addColumn("SourcePort");
model.addColumn("DestPort");
model.addColumn("Protocol");
bstart.addActionListener(this);
bpause.addActionListener(this);
bclose.addActionListener(this);
setSize(450,250);
setTitle("ALL PROTOCOLS");
show();
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource() == bstart)
{
th.start();
bstart.setEnabled(false);
}
if(e.getSource() == bpause)
{
if(bpause.getText().equals("Pause Sniff"))
{
bpause.setText("Continue Sniff..");
SniffStatus = false;
}
else
{
bpause.setText("Pause Sniff");
SniffStatus = true;
}
}
if(e.getSource() == bclose)
{
SniffStatus=false;
dispose();
}
}
class PacketSniff implements JpcapHandler
{
public void handlePacket(Packet pac)
{
try
{
if(SniffStatus)
{
IPPacket ip = (IPPacket)pac;
IPAddress sadr = ip.src_ip;
IPAddress dadr = ip.dst_ip;
int proto = (int)ip.protocol;
if(proto == 17)
{
st="UDP";
String sip = sadr.getHostAddress();
String dip = dadr.getHostAddress();
UDPPacket up = (UDPPacket)pac;
String sport = "" + up.src_port;
String dport = "" + up.dst_port;
model.addRow(new Object[]{sip,dip,sport,dport,st});
}
else if(proto == 2)
{
st="IGMP";
String sip = sadr.getHostAddress();
String dip = dadr.getHostAddress();
TCPPacket tp = (TCPPacket)pac;
String sport = "" + tp.src_port;
String dport = "" + tp.dst_port;
model.addRow(new Object[]{sip,dip,sport,dport,st});
}
else if(proto == 1 )
{
st="ICMP";
String sip = sadr.getHostAddress();
String dip = dadr.getHostAddress();
TCPPacket tp = (TCPPacket)pac;
String sport = "" + tp.src_port;
String dport = "" + tp.dst_port;
String seq="" +tp.sequence;
model.addRow(new Object[]{sip,dip,sport,dport,st});
}
else if(proto == 6)
{
st="TCP";
String sip = sadr.getHostAddress();
String dip = dadr.getHostAddress();
TCPPacket tp = (TCPPacket)pac;
String sport = "" + tp.src_port;
String dport = "" + tp.dst_port;
String seq="" +tp.sequence;
model.addRow(new Object[]{sip,dip,sport,dport,st});
}
}
else
return;
}
catch(Exception e)
{
pane1.showMessageDialog(f1,"Error occured");
}
}
}
class Thread1 extends Thread
{
public void run()
{
try
{
String[] devices=Jpcap.getDeviceList();
String val="";
for(int j=0;j<50;j++)
{
val=val+devices[j];
}
Jpcap jpcap=Jpcap.openDevice(val,10000,false,20);
jpcap.loopPacket(-1,new PacketSniff());
}
catch(Exception e1)
{
pane1.showMessageDialog(f1,"Error occured");
}
}
}
}
Message was edited by:
java_bla
