SYNOPSIS
--------
Double byte characters corrupted in DN for LDAP referrals

OPERATING SYSTEM
----------------
All

FULL JDK VERSION
----------------
All

DESCRIPTION
-----------

If the DN component of an LDAP URL contains double byte characters, it is corrupted by com.sun.jndi.toolkit.url.UrlUtil.decode(). This corruption leads to application level failures.

Consider the following scenario:

1. Application connects to an LDAP server and searches for the string
   uid=???,??? (where ??? are double byte characters)

2. JNDI code receives a referral, for example:
   ldap://www.test.com/uid=???,???,ou=people,ou=test,ou=test,o=test

3. The referral is then parsed to split the hostname, port number and
   the DN element of the URI via
   com.sun.jndi.ldap.LdapURL.parsePathAndQuery()

4. The DN element is decoded using
   com.sun.jndi.toolkit.url.UrlUtil.decode()

5. This method expects the characters to be ASCII. If the characters
   are non-ASCII, as in our example, then those characters are not
   converted properly.

6. This corrupted DN is then passed to the LDAP server, resulting in an
   unexpected failure.

TESTCASE
--------
This testcase does not represent normal application code. It highlights the problem by calling into com.sun.* internal classes directly. This allows the problem to be demonstrated without setting up an LDAP server.

import java.net.URI;
import java.net.URLDecoder;
import com.sun.jndi.ldap.LdapURL;

public class LdapURLTest {
    public static void main (String args[]) throws Exception {
        String testString = ("ldap://www.test.com/uid=\u3070\u3073\u3076,\u3079\u307C\u307E,ou=test,ou=test,ou=test,o=test");
        LdapURL ldURL = new LdapURL(testString);
        System.out.println(" LDAP URL String: " + testString);
        System.out.println(" decoded DN: " + ldURL.getDN());

        // suggested fix demonstration
        String DN;
        String path = new URI(testString).getPath();

        DN = path.startsWith("/") ? path.substring(1) : path;
        String proposedDN = URLDecoder.decode(DN, "UTF8");

        System.out.println("\nDN from proposed fix: " + proposedDN);
    }
}

SUGGESTED FIX
-------------
Use java.net.URLDecoder rather than com.sun.jndi.toolkit.url.UrlUtil to conduct the URL decoding in parsePathAndQuery().

Specifically, change the line that decodes the DN element in com.sun.jndi.ldap.LdapURL.parsePathAndQuery() from:

    DN = path.startsWith("/") ? path.substring(1) : path;
    if (DN.length() > 0) {
--> DN = UrlUtil.decode(DN, "UTF8"); <--
    }

to:

    DN = path.startsWith("/") ? path.substring(1) : path;
    if (DN.length() > 0) {
--> DN = URLDecoder.decode(DN, "UTF8"); <--
    }