Java LDAP - Determine if user in a given group?

Question

We logon users to Active Directory via LDAP using the Java LDAP API. We want to enhance our logon functionality to further check if the user is in a given AD group. Does a

Answer 1

We solved this with the class below. Just call the authenticate method:

import java.text.MessageFormat;
import java.util.*;    
import javax.naming.*;    
import org.apache.log4j.Level;

public class LdapGroupAuthenticator {
    public static final String DISTINGUISHED_NAME = "distinguishedName";
    public static final String CN = "cn";
    public static final String MEMBER = "member";
    public static final String MEMBER_OF = "memberOf";
    public static final String SEARCH_BY_SAM_ACCOUNT_NAME = "(SAMAccountName={0})";
    public static final String SEARCH_GROUP_BY_GROUP_CN = "(&(objectCategory=group)(cn={0}))";

    /*
     * Prepares and returns CN that can be used for AD query
     * e.g. Converts "CN=**Dev - Test Group" to "**Dev - Test Group"
     * Converts CN=**Dev - Test Group,OU=Distribution Lists,DC=DOMAIN,DC=com to "**Dev - Test Group"
     */
    public static String getCN(String cnName) {
        if (cnName != null && cnName.toUpperCase().startsWith("CN=")) {
            cnName = cnName.substring(3);
        }
        int position = cnName.indexOf(',');
        if (position == -1) {
            return cnName;
        } else {
            return cnName.substring(0, position);
        }
    }
    public static boolean isSame(String target, String candidate) {
        if (target != null && target.equalsIgnoreCase(candidate)) {
            return true;
        }
        return false;
    }

    public static boolean authenticate(String domain, String username, String password) {
        Hashtable env = new Hashtable();
        env.put(Context.INITIAL_CONTEXT_FACTORY,"com.sun.jndi.ldap.LdapCtxFactory");
        env.put(Context.PROVIDER_URL, "ldap://1.2.3.4:389");
        env.put(Context.SECURITY_AUTHENTICATION, "simple");
        env.put(Context.SECURITY_PRINCIPAL, domain + "\\" + username);
        env.put(Context.SECURITY_CREDENTIALS, password);
        DirContext ctx = null;
        String defaultSearchBase = "DC=DOMAIN,DC=com";
        String groupDistinguishedName = "DN=CN=DLS-APP-MyAdmin-C,OU=DLS File Permissions,DC=DOMAIN,DC=com";

        try {
            ctx = new InitialDirContext(env);

            // userName is SAMAccountName
            SearchResult sr = executeSearchSingleResult(ctx, SearchControls.SUBTREE_SCOPE, defaultSearchBase,
                    MessageFormat.format( SEARCH_BY_SAM_ACCOUNT_NAME, new Object[] {username}),
                    new String[] {DISTINGUISHED_NAME, CN, MEMBER_OF}
                    );

            String groupCN = getCN(groupDistinguishedName);
            HashMap processedUserGroups = new HashMap();
            HashMap unProcessedUserGroups = new HashMap();

            // Look for and process memberOf
            Attribute memberOf = sr.getAttributes().get(MEMBER_OF);
            if (memberOf != null) {
                for ( Enumeration e1 = memberOf.getAll() ; e1.hasMoreElements() ; ) {
                    String unprocessedGroupDN = e1.nextElement().toString();
                    String unprocessedGroupCN = getCN(unprocessedGroupDN);
                    // Quick check for direct membership
                    if (isSame (groupCN, unprocessedGroupCN) && isSame (groupDistinguishedName, unprocessedGroupDN)) {
                        Log.info(username + " is authorized.");
                        return true;
                    } else {
                        unProcessedUserGroups.put(unprocessedGroupDN, unprocessedGroupCN);
                    }
                }
                if (userMemberOf(ctx, defaultSearchBase, processedUserGroups, unProcessedUserGroups, groupCN, groupDistinguishedName)) {
                    Log.info(username + " is authorized.");
                    return true;
                }
            }

            Log.info(username + " is NOT authorized.");
            return false;
        } catch (AuthenticationException e) {
            Log.info(username + " is NOT authenticated");
            return false;
        } catch (NamingException e) {
            throw new SystemException(e);
        } finally {
            if (ctx != null) {
                try {
                    ctx.close();
                } catch (NamingException e) {
                    throw new SystemException(e);
                }
            }
        }
    }

    public static boolean userMemberOf(DirContext ctx, String searchBase, HashMap processedUserGroups, HashMap unProcessedUserGroups, String groupCN, String groupDistinguishedName) throws NamingException {
        HashMap newUnProcessedGroups = new HashMap();
        for (Iterator entry = unProcessedUserGroups.keySet().iterator(); entry.hasNext();) {
            String  unprocessedGroupDistinguishedName = (String) entry.next();
            String unprocessedGroupCN = (String)unProcessedUserGroups.get(unprocessedGroupDistinguishedName);
            if ( processedUserGroups.get(unprocessedGroupDistinguishedName) != null) {
                Log.info("Found  : " + unprocessedGroupDistinguishedName +" in processedGroups. skipping further processing of it..." );
                // We already traversed this.
                continue;
            }
            if (isSame (groupCN, unprocessedGroupCN) && isSame (groupDistinguishedName, unprocessedGroupDistinguishedName)) {
                Log.info("Found Match DistinguishedName : " + unprocessedGroupDistinguishedName +", CN : " + unprocessedGroupCN );
                return true;
            }
        }

        for (Iterator entry = unProcessedUserGroups.keySet().iterator(); entry.hasNext();) {
            String  unprocessedGroupDistinguishedName = (String) entry.next();
            String unprocessedGroupCN = (String)unProcessedUserGroups.get(unprocessedGroupDistinguishedName);

            processedUserGroups.put(unprocessedGroupDistinguishedName, unprocessedGroupCN);

            // Fetch Groups in unprocessedGroupCN and put them in newUnProcessedGroups
            NamingEnumeration ns = executeSearch(ctx, SearchControls.SUBTREE_SCOPE, searchBase,
                    MessageFormat.format( SEARCH_GROUP_BY_GROUP_CN, new Object[] {unprocessedGroupCN}),
                    new String[] {CN, DISTINGUISHED_NAME, MEMBER_OF});

            // Loop through the search results
            while (ns.hasMoreElements()) {
                SearchResult sr = (SearchResult) ns.next();

                // Make sure we're looking at correct distinguishedName, because we're querying by CN
                String userDistinguishedName = sr.getAttributes().get(DISTINGUISHED_NAME).get().toString();
                if (!isSame(unprocessedGroupDistinguishedName, userDistinguishedName)) {
                    Log.info("Processing CN : " + unprocessedGroupCN + ", DN : " + unprocessedGroupDistinguishedName +", Got DN : " + userDistinguishedName +", Ignoring...");
                    continue;
                }

                Log.info("Processing for memberOf CN : " + unprocessedGroupCN + ", DN : " + unprocessedGroupDistinguishedName);
                // Look for and process memberOf
                Attribute memberOf = sr.getAttributes().get(MEMBER_OF);
                if (memberOf != null) {
                    for ( Enumeration e1 = memberOf.getAll() ; e1.hasMoreElements() ; ) {
                        String unprocessedChildGroupDN = e1.nextElement().toString();
                        String unprocessedChildGroupCN = getCN(unprocessedChildGroupDN);
                        Log.info("Adding to List of un-processed groups : " + unprocessedChildGroupDN +", CN : " + unprocessedChildGroupCN);
                        newUnProcessedGroups.put(unprocessedChildGroupDN, unprocessedChildGroupCN);
                    }
                }
            }
        }
        if (newUnProcessedGroups.size() == 0) {
            Log.info("newUnProcessedGroups.size() is 0. returning false...");
            return false;
        }

        //  process unProcessedUserGroups
        return userMemberOf(ctx, searchBase, processedUserGroups, newUnProcessedGroups, groupCN, groupDistinguishedName);
    }

    private static NamingEnumeration executeSearch(DirContext ctx, int searchScope,  String searchBase, String searchFilter, String[] attributes) throws NamingException {
        // Create the search controls
        SearchControls searchCtls = new SearchControls();

        // Specify the attributes to return
        if (attributes != null) {
            searchCtls.setReturningAttributes(attributes);
        }

        // Specify the search scope
        searchCtls.setSearchScope(searchScope);

        // Search for objects using the filter
        NamingEnumeration result = ctx.search(searchBase, searchFilter,searchCtls);
        return result;
    }

    private static SearchResult executeSearchSingleResult(DirContext ctx, int searchScope,  String searchBase, String searchFilter, String[] attributes) throws NamingException {
        NamingEnumeration result = executeSearch(ctx, searchScope,  searchBase, searchFilter, attributes);

        SearchResult sr = null;
        // Loop through the search results
        while (result.hasMoreElements()) {
            sr = (SearchResult) result.next();
            break;
        }
        return sr;
    }
}