Java application cannot bind to IPv6 socket on dual stack machines, if IPv4
socket is already bound and setReuseAddress is "false".

The problem is strictly reproducible.

1. Precondition
---------------
 Please make sure that you are on a dual stack machine and inet6 interface
 is up:
% ifconfig -a
lo0: flags=1000849<UP,LOOPBACK,RUNNING,MULTICAST,IPv4> mtu 8232 index 1
        inet 127.0.0.1 netmask ff000000
eri0: flags=1000843<UP,BROADCAST,RUNNING,MULTICAST,IPv4> mtu 1500 index 2
        inet 129.157.133.192 netmask ffffff00 broadcast 129.157.133.255
eri0: flags=2000841<UP,RUNNING,MULTICAST,IPv6> mtu 1500 index 2
        inet6 fe80::203:baff:fe5b:7e89/10

 If inet6 interface is not up, use:
# ifconfig eri0 inet6 plumb up


2. Testcase
-----------
 The testcase consists of a C program "v4serv.c" creating and binding to
 an IPv4 socket, and a Java program "NoReuse.java" creating and binding to
 an IPv6 socket (per default).

% more v4serv.c
#include <stdio.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <netdb.h>

main(int argc, char *argv[]) {

        struct sockaddr_in addr;
        int new_sock, sock;
        int yes=0;
        char buf[BUFSIZ];

        bzero(&addr, sizeof(addr));
        addr.sin_family = AF_INET;
        addr.sin_addr.s_addr = htonl(INADDR_ANY);
        addr.sin_port = htons(3300);

        if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
                perror("socket");
                return -1;
        }

        setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&yes, sizeof(int));
        if (bind(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
                perror("bind");
                return -1;
        }

        listen(sock, 8);

        for(;;){
                new_sock = accept(sock, NULL, NULL);
                read(new_sock, buf, sizeof (buf));
                printf("%s", buf);
                close(new_sock);
        }

}
% more NoReuse.java
import java.net.*;
import java.io.*;

class NoReuse{

    public static String messages[]
      = {"test1", "test2", "test3" };

        public static void main(String args[]){

                try{

                        ServerSocket ss = new ServerSocket();
                        ss.setReuseAddress(false);
                        ss.bind( new InetSocketAddress(3300) );
                        Socket s = ss.accept();

            BufferedWriter writer
              = new BufferedWriter(
                  new OutputStreamWriter( s.getOutputStream() ) );
            for( int i=0; i<messages.length; i++ ) {
                 writer.write( messages[i], 0, messages[i].length() );
                 writer.newLine();
            }

                        writer.close();
                        s.close();

                }catch(UnknownHostException e){
                        System.out.println(e.toString());
                }catch(SocketException e){
                        System.out.println(e.toString());
                }catch(IOException e){
                        System.out.println(e.toString());
                }
        }
}
%


3. Make
-------
% /opt/SUNWspro/bin/cc -V v4serv.c -o v4serv -lsocket -lnsl
cc: Sun C 5.5 Patch 112760-11 2004/06/08
acomp: Sun C 5.5 Patch 112760-11 2004/06/08
"v4serv.c", line 7: warning: old-style declaration or incorrect type for: main
"v4serv.c", line 14: warning: implicit function declaration: bzero
"v4serv.c", line 34: warning: implicit function declaration: read
"v4serv.c", line 36: warning: implicit function declaration: close
ld: Software Generation Utilities - Solaris Link Editors: 5.9-1.343
% /j2sdk1.4.2_07/bin/javac NoReuse.java
%


4. Run w/ setReuseAddress(false)
--------------------------------
4.1 First "v4serv" then "NoReuse"
---------------------------------
% netstat -a | grep 3300
% ./v4serv &
[1] 16398
% netstat -a | grep 3300
      *.3300 *.* 0 0 49152 0 LISTEN
% /j2sdk1.4.2_07/bin/java NoReuse
java.net.BindException: Address already in use
%
 Does not work.

4.2 First "NoReuse" then "v4serv"
---------------------------------
% netstat -a | grep 3300
% /j2sdk1.4.2_07/bin/java NoReuse &
[1] 16410
% netstat -a | grep 3300
      *.3300 *.* 0 0 49152 0 LISTEN
      *.3300 *.* 0 0 49152 0 LISTEN
% ./v4serv
% bind: Address already in use
%
 Does not work.


5. Run w/ setReuseAddress(true)
-------------------------------
 change line 14 in NoReuse.java:
    14 ss.setReuseAddress(true);
5.1 First "v4serv" then "NoReuse"
---------------------------------
% netstat -a | grep 3300
% ./v4serv &
[1] 16438
% netstat -a | grep 3300
      *.3300 *.* 0 0 49152 0 LISTEN
% /net/redback/data/j2sdk1.4.2_07/bin/java NoReuse &
[2] 16441
% netstat -a | grep 3300
      *.3300 *.* 0 0 49152 0 LISTEN
      *.3300 *.* 0 0 49152 0 LISTEN
      *.3300 *.* 0 0 49152 0 LISTEN
%
 Everything fine here.

5.2 First "NoReuse" then "v4serv"
---------------------------------
% netstat -a | grep 3300
% /j2sdk1.4.2_07/bin/java NoReuse &
[1] 16450
% netstat -a | grep 3300
      *.3300 *.* 0 0 49152 0 LISTEN
      *.3300 *.* 0 0 49152 0 LISTEN
% ./v4serv &
[2] 16453
% netstat -a | grep 3300
      *.3300 *.* 0 0 49152 0 LISTEN
      *.3300 *.* 0 0 49152 0 LISTEN
      *.3300 *.* 0 0 49152 0 LISTEN
%
 Everything fine here.

###@###.### 2005-03-22 14:30:27 GMT