Hi, I was trying to figure this out. I've been scratching my head all morning and I'm at a mental dead end. Can anyone help me?
Malicious code in red
/*
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package ping;
import java.net.*;
import java.text.SimpleDateFormat;
import java.util.*;
public class PingClient
{
private static final int PING_MESSAGES = 10;
private static final int TOKEN_TIMESTAMP = 2;
private static final int MAX_WAIT_TIME = 1000;
private static final String CRLF = "\r\n";
public static void main(String[] args) throws Exception
{
// If user doesn't input both port number and ip address, the program will display an error message.
if (args.length != 2)
{
System.out.println("usage: java PingClient <Host> <Port>");
//return;
}
try
{
if(!args[0].isEmpty())
System.out.println("\nHost: "+args[1]+"\nIP address: "+args[0]+"\n");
}
catch(ArrayIndexOutOfBoundsException e)
{
System.out.println("Host name and ip address please");
System.exit(1);
}
byte[] buffer = new byte[1024];
//InetAddress host = InetAddress.getByName(args[0]);
InetAddress host = InetAddress.getByName("localhost");
int portNumber = Integer.parseInt(args[1]);
//Create a datagram socket used for sending and recieving UDP packets
// DatagramSocket socket = new DatagramSocket(new byte[1024],9876, 172.16.202.88, 1024);
DatagramSocket socket = new DatagramSocket(buffer, buffer.length);
//Set up the maximum time the socket waits for responses
socket.setSoTimeout(MAX_WAIT_TIME);
//Construct a ping message to be sent to the Server
for (int sequence_num = 0; sequence_num < PING_MESSAGES; sequence_num++)
{
String message = generatePing(sequence_num);
DatagramPacket ping_request =
new DatagramPacket(message.getBytes(), message.length(), host, portNumber);
//Send a ping request
socket.send(ping_request);
//Datagram packet to hold server response
DatagramPacket ping_response =
new DatagramPacket(new byte[message.length()], message.length());
//Wait for ping response from server
try
{
socket.receive(ping_response);
printData(ping_response);
}
catch (SocketTimeoutException e)
{
System.out.println("No response was received from the server");
}
catch (Exception e)
{
//Another unknown error may have occured that can't be handled
e.printStackTrace(System.out);
return;
}
}
}
private static String generatePing(int sequence_num)
{
// For getting current date and time
SimpleDateFormat sdfNow = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");
String strNow = sdfNow.format(new Date(System.currentTimeMillis()));
return "PING #" + sequence_num + " " + System.currentTimeMillis() + " ("+strNow+")";
}
//Print ping page to standard output stream
private static void printData(DatagramPacket request) throws Exception
{
String response = new String(request.getData());
String[] tokens = response.split(" ");
//Create sent and received timestamps for RTT
long sent_timestamp = new Long(tokens[TOKEN_TIMESTAMP]);
long received_timestamp = System.currentTimeMillis();
//RTT
long rtt = received_timestamp - sent_timestamp;
//Display results
System.out.print(response+" Received from "+
request.getAddress().getHostAddress() + " "+"(RTT=" + rtt + "ms)"+CRLF);
}
}
