Name: yyC67448 Date: 10/29/97



The java.net.MulticastSocket.send(DatagramPacket, byte) alter default ttl
for the socket if an IOException raised while sending the packet.


   --- Here is the javadoc comment for this method ---
    /**
     * Sends a datagram packet to the destination, with a TTL (time-
     * to-live) other than the default for the socket. This method
     * need only be used in instances where a particular TTL is desired;
     * otherwise it is preferable to set a TTL once on the socket, and
     * use that default TTL for all packets. This method does <B>not
     * </B> alter the default TTL for the socket.
     * @param p is the packet to be sent. The packet should contain
     * the destination multicast ip address and the data to be sent.
     * One does not need to be the member of the group to send
     * packets to a destination multicast address.
     * @param ttl optional time to live for multicast packet.
     * default ttl is 1.
     * @exception IOException is raised if an error occurs i.e
     * error while setting ttl.
     * @see DatagramSocket#send
     * @see DatagramSocket#receive
     * @since JDK1.1
     */
    public synchronized void send(DatagramPacket p, byte ttl)



Here is the test demonstrating the bug:

-------------------------------- Test.java -----------------------------
import java.io.*;
import java.net.*;


class test
{

  public static void main(String args[])
  {
    MulticastSocket soc = null;
    DatagramPacket pac = null;
    InetAddress sin = null;
    byte [] array = new byte[65537];
    int port = 0;
    byte old_ttl = 0;
    byte new_ttl = 64;
    byte ttl = 0;


    try {
      /*
       * This address makes NO difference..
       */
      sin = InetAddress.getByName("224.80.80.80");
    } catch(Exception e)
    {
      System.out.println("Failed. Can not get InetAddress for 224.80.80.80:" + e);
      System.exit(-1);
    }
    
    try {
      soc = new MulticastSocket();
      port = soc.getLocalPort();
      old_ttl = soc.getTTL();
    } catch(SecurityException e)
    {
      SecurityManager sec = System.getSecurityManager();
      if(sec != null)
      {
try {
sec.checkListen(0);
System.out.println("Failed. Unexpected SecurityException:" + e);
System.exit(-1);
} catch(SecurityException e1)
{
System.out.println("Correctly failed to setup test; SecurityException");
System.exit(-1);
}
      }
    }
    catch(Exception e)
    {
      System.out.println("Failed.Can not create MulticastSocket:" + e);
      System.exit(-1);
    }
    
    pac = new DatagramPacket(array, array.length, sin, port);
    
    try {
      /*
       * Try to send packet, which is too big...
       */
      soc.send(pac, new_ttl);
    } catch(java.io.IOException e)
    {
      /*
       * So, this is what we expect...
       */
      try {
ttl = soc.getTTL();
      } catch(Exception e1)
      {
soc.close();
System.out.println("Failed.Can not get TTL:" + e);
System.exit(-1);
      }
      soc.close();
      if(ttl == old_ttl)
System.out.println("Passed.OKAY");
      else
System.out.println("TTL values mismatch. old_ttl = " + old_ttl + " new_ttl = " + ttl);
      System.exit(0);
    }
    catch(Exception e)
    {
      soc.close();
      System.out.println("Failed. Unexpected exception:" + e);
      System.exit(-1);
    }
    
    soc.close();
    System.out.println("Failed.No exceptions...");
    System.exit(-1);
    
    
  }
  
}


---------------------- Output from the test -----------------
TTL values mismatch. old_ttl = 1 new_ttl = 64
-----------------------------------------------------------------
======================================================================