HADOOP-13565. KerberosAuthenticationHandler#authenticate should not rebuild SPN based on client request. Contributed by Xiaoyu Yao.

(cherry picked from commit 9097e2efe4c92d83c8fab88dc11be84505a6cab5)

hadoop-common-project/hadoop-auth/src/main/java/org/apache/hadoop/security/authentication/server/KerberosAuthenticationHandler.java

@@ -343,8 +343,6 @@ public class KerberosAuthenticationHandler implements AuthenticationHandler {
       authorization = authorization.substring(KerberosAuthenticator.NEGOTIATE.length()).trim();
       final Base64 base64 = new Base64(0);
       final byte[] clientToken = base64.decode(authorization);
-      final String serverName = InetAddress.getByName(request.getServerName())
-                                           .getCanonicalHostName();
       try {
         token = Subject.doAs(serverSubject, new PrivilegedExceptionAction<AuthenticationToken>() {
 
@@ -354,10 +352,7 @@ public class KerberosAuthenticationHandler implements AuthenticationHandler {
             GSSContext gssContext = null;
             GSSCredential gssCreds = null;
             try {
-              gssCreds = gssManager.createCredential(
-                  gssManager.createName(
-                      KerberosUtil.getServicePrincipal("HTTP", serverName),
-                      KerberosUtil.getOidInstance("NT_GSS_KRB5_PRINCIPAL")),
+              gssCreds = gssManager.createCredential(null,
                   GSSCredential.INDEFINITE_LIFETIME,
                   new Oid[]{
                     KerberosUtil.getOidInstance("GSS_SPNEGO_MECH_OID"),