// get client principal key to verify (if available)
KerberosInfo krbInfo = SecurityUtil.getKerberosInfo(protocol, conf);
String clientPrincipal = null;
if (krbInfo != null) {
String clientKey = krbInfo.clientPrincipal();
if (clientKey != null && !clientKey.isEmpty()) {
try {
clientPrincipal = SecurityUtil.getServerPrincipal(
conf.get(clientKey), addr);
} catch (IOException e) {