A {@link javax.naming.spi.ObjectFactoryBuilder} implementation to filter out referral references if they do not
+ * point to an LDAP URL.
+ *
+ * When the LDAP provider encounters a referral, it tries to create an {@link ObjectFactory} from this builder.
+ * If the referral reference contains an LDAP URL, a {@link DirContextObjectFactory} is created to handle the referral.
+ * Otherwise, a {@link CommunicationException} is thrown to indicate that the referral cannot be processed.
+ */
+final class ObjectFactoryBuilder implements javax.naming.spi.ObjectFactoryBuilder, ObjectFactory {
+
+ private static final Logger logger = Logger.getLogger(ObjectFactoryBuilder.class);
+ private static final String IS_KC_OBJECT_FACTORY_BUILDER = "kc.jndi.object.factory.builder";
+
+ static boolean isSet() {
+ Hashtable env = new Hashtable<>();
+
+ env.put(ObjectFactoryBuilder.IS_KC_OBJECT_FACTORY_BUILDER, Boolean.TRUE);
+
+ try {
+ Object instance = NamingManager.getObjectInstance(null, null, null, env);
+
+ if (instance != null && instance.getClass().getName().equals(ObjectFactoryBuilder.class.getName())) {
+ return true;
+ }
+ } catch (Exception e) {
+ throw new RuntimeException("Failed to determine if ObjectFactoryBuilder is set", e);
+ }
+
+ return false;
+ }
+
+ @Override
+ public ObjectFactory createObjectFactory(Object obj, Hashtable environment) throws NamingException {
+ if (logger.isTraceEnabled()) {
+ logger.tracef("Creating ObjectFactory for object: %s", obj);
+ }
+
+ if (obj instanceof Reference ref) {
+ String factoryClassName = ref.getFactoryClassName();
+
+ if (factoryClassName != null) {
+ logger.warnf("Referral refence contains an object factory %s but it will be ignored", factoryClassName);
+ }
+
+ String ldapUrl = getLdapUrl(ref);
+
+ if (ldapUrl != null) {
+ return new DirContextObjectFactory(ldapUrl);
+ }
+ } else {
+ logger.debugf("Unsupported reference object of type %s: ", obj);
+ return this;
+ }
+
+ throw new CommunicationException("Referral reference does not contain an LDAP URL: " + obj);
+ }
+
+ @Override
+ public Object getObjectInstance(Object obj, Name name, Context nameCtx, Hashtable env) {
+ if (env != null && env.containsKey(IS_KC_OBJECT_FACTORY_BUILDER)) {
+ return this;
+ }
+ return obj;
+ }
+
+ private String getLdapUrl(Reference ref) {
+ for (int i = 0; i < ref.size(); i++) {
+ RefAddr addr = ref.get(i);
+ String addrType = addr.getType();
+
+ if ("URL".equalsIgnoreCase(addrType)) {
+ Object content = addr.getContent();
+
+ if (content == null) {
+ return null;
+ }
+
+ String rawUrl = content.toString();
+
+ for (String url : List.of(rawUrl.split(" "))) {
+ if (!url.toLowerCase().startsWith("ldap")) {
+ logger.warnf("Unsupported scheme from reference URL %s. Ignoring reference.", url);
+ return null;
+ }
+ }
+
+ return rawUrl;
+ } else {
+ logger.warnf("Ignoring address of type '%s' from referral reference", addrType);
+ }
+ }
+
+ return null;
+ }
+
+ private record DirContextObjectFactory(String ldapUrl) implements ObjectFactory {
+
+ @Override
+ public Object getObjectInstance(Object obj, Name name, Context nameCtx, Hashtable env) throws Exception {
+ @SuppressWarnings("unchecked")
+ Hashtable newEnv = (Hashtable) env.clone();
+ newEnv.put(LdapContext.PROVIDER_URL, ldapUrl);
+ return new SessionBoundInitialLdapContext(KeycloakSessionUtil.getKeycloakSession(), newEnv, null);
+ }
+ }
+}