The LDAP service provider throws a NullPointerException when a referral
is returned by an LDAP server during an LDAP Bind operation. Referrals
received during other LDAP operations are handled correctly.

To reproduce:

1) Create a person entry in LDAP server A which contains a referral to
   LDAP server B. For example, create a ref attribute with the value
   "ldap://serverB" in an entry named "cn=personB,o=sun,c=us" in server A.

2) Use the simple JNDI application below to perform an LDAP Bind operation
   to server A using the DN of the person entry above. For example,

       java AuthRead ldap://serverA "cn=personB,o=sun,c=us" "xxx"

   Server A will return a referral to server B. The LDAP service provider
   will throw a NullPointerException while processing this referral.



import java.util.Hashtable;
import java.util.Enumeration;

import javax.naming.*;
import javax.naming.directory.*;

class AuthRead {

public static void main(String[] args) {

    int argc = args.length;

    if ((argc < 3) ||
        ((argc == 1) && (args[0].equalsIgnoreCase("-help")))) {

        System.out.println("Usage: AuthRead <ldapurl> <DN> <password>\n");
        System.out.println(" <ldapurl> is the LDAP URL of the entry to read"
);
        System.out.println(" <DN> is the principal's name");
        System.out.println(" <password> is the principal's credential\n");
        System.out.println("example:");
        System.out.println(" java AuthRead ldap://oasis/o=airius.com \"cn=dir
ectory manager\" secret99");
        return;
    }

    Hashtable env = new Hashtable(5, 0.75f);

    env.put(Context.INITIAL_CONTEXT_FACTORY,
        "com.sun.jndi.ldap.LdapCtxFactory");

    /* Specify host and port to use for directory service */
    env.put(Context.PROVIDER_URL, args[0]);

    /* specify authentication information */
    env.put(Context.SECURITY_AUTHENTICATION, "simple");
    env.put(Context.SECURITY_PRINCIPAL, args[1]);
    env.put(Context.SECURITY_CREDENTIALS, args[2]);

    /* Chase referrals */
    env.put(Context.REFERRAL, "follow");

    try {
        /* get a handle to an Initial DirContext */
        DirContext ctx = new InitialDirContext(env);

        Attributes attrs = ctx.getAttributes("");
        if (attrs == null) {
            System.out.println("No attributes");
        } else {
            /* print each attribute */
            for (NamingEnumeration ae = attrs.getAll();
                ae.hasMoreElements();) {
                Attribute attr = (Attribute)ae.next();
                String attrId = attr.getID();

                /* print each value */
                for (Enumeration vals = attr.getAll();
                    vals.hasMoreElements();
                    System.out.println(attrId + ": " + vals.nextElement()))
                        ;
                }
            }
    } catch (NamingException e) {
        System.err.println("AuthRead failed.");
        e.printStackTrace();
    }
}
}