From 0d47d283a611b10cb7a842712cb01fa0c043bdc4 Mon Sep 17 00:00:00 2001
From: Akira Ajisaka <aajisaka@apache.org>
Date: Mon, 8 Apr 2019 10:02:34 +0900
Subject: [PATCH] HADOOP-10848. Cleanup calling of sun.security.krb5.Config.

---
 .../authentication/util/KerberosUtil.java     | 49 ++++++++++---------
 .../client/impl/zk/RegistrySecurity.java      | 17 ++-----
 2 files changed, 29 insertions(+), 37 deletions(-)

diff --git a/hadoop-common-project/hadoop-auth/src/main/java/org/apache/hadoop/security/authentication/util/KerberosUtil.java b/hadoop-common-project/hadoop-auth/src/main/java/org/apache/hadoop/security/authentication/util/KerberosUtil.java
index 4459928ff5..4319aa5b0d 100644
--- a/hadoop-common-project/hadoop-auth/src/main/java/org/apache/hadoop/security/authentication/util/KerberosUtil.java
+++ b/hadoop-common-project/hadoop-auth/src/main/java/org/apache/hadoop/security/authentication/util/KerberosUtil.java
@@ -24,7 +24,6 @@
 import java.io.UnsupportedEncodingException;
 import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
 import java.net.InetAddress;
 import java.net.UnknownHostException;
 import java.nio.ByteBuffer;
@@ -44,6 +43,7 @@
 import org.ietf.jgss.Oid;
 
 import javax.security.auth.Subject;
+import javax.security.auth.kerberos.KerberosPrincipal;
 import javax.security.auth.kerberos.KerberosTicket;
 import javax.security.auth.kerberos.KeyTab;
 
@@ -90,36 +90,37 @@ public static Oid getOidInstance(String oidName)
     return (Oid)oidField.get(oidClass);
   }
 
-  public static String getDefaultRealm() 
-      throws ClassNotFoundException, NoSuchMethodException, 
-      IllegalArgumentException, IllegalAccessException, 
+  /**
+   * Return the default realm for this JVM.
+   *
+   * @return The default realm
+   * @throws IllegalArgumentException If the default realm does not exist.
+   * @throws ClassNotFoundException Not thrown. Exists for compatibility.
+   * @throws NoSuchMethodException Not thrown. Exists for compatibility.
+   * @throws IllegalAccessException Not thrown. Exists for compatibility.
+   * @throws InvocationTargetException Not thrown. Exists for compatibility.
+   */
+  public static String getDefaultRealm()
+      throws ClassNotFoundException, NoSuchMethodException,
+      IllegalArgumentException, IllegalAccessException,
       InvocationTargetException {
-    Object kerbConf;
-    Class<?> classRef;
-    Method getInstanceMethod;
-    Method getDefaultRealmMethod;
-    if (IBM_JAVA) {
-      classRef = Class.forName("com.ibm.security.krb5.internal.Config");
-    } else {
-      classRef = Class.forName("sun.security.krb5.Config");
-    }
-    getInstanceMethod = classRef.getMethod("getInstance", new Class[0]);
-    kerbConf = getInstanceMethod.invoke(classRef, new Object[0]);
-    getDefaultRealmMethod = classRef.getDeclaredMethod("getDefaultRealm",
-         new Class[0]);
-    return (String)getDefaultRealmMethod.invoke(kerbConf, new Object[0]);
+    // Any name is okay.
+    return new KerberosPrincipal("tmp", 1).getRealm();
   }
 
+  /**
+   * Return the default realm for this JVM.
+   * If the default realm does not exist, this method returns null.
+   *
+   * @return The default realm
+   */
   public static String getDefaultRealmProtected() {
-    String realmString = null;
     try {
-      realmString = getDefaultRealm();
-    } catch (RuntimeException rte) {
-      //silently catch everything
+      return getDefaultRealm();
     } catch (Exception e) {
-      //silently return null
+      //silently catch everything
+      return null;
     }
-    return realmString;
   }
 
   /*
diff --git a/hadoop-common-project/hadoop-registry/src/main/java/org/apache/hadoop/registry/client/impl/zk/RegistrySecurity.java b/hadoop-common-project/hadoop-registry/src/main/java/org/apache/hadoop/registry/client/impl/zk/RegistrySecurity.java
index 12a41337cb..dac11353a4 100644
--- a/hadoop-common-project/hadoop-registry/src/main/java/org/apache/hadoop/registry/client/impl/zk/RegistrySecurity.java
+++ b/hadoop-common-project/hadoop-registry/src/main/java/org/apache/hadoop/registry/client/impl/zk/RegistrySecurity.java
@@ -42,7 +42,6 @@
 import javax.security.auth.login.AppConfigurationEntry;
 import java.io.File;
 import java.io.IOException;
-import java.lang.reflect.InvocationTargetException;
 import java.security.NoSuchAlgorithmException;
 import java.util.ArrayList;
 import java.util.Collections;
@@ -1039,19 +1038,11 @@ private static String describeProperty(String name, String def) {
    * could be determined
    */
   public static String getDefaultRealmInJVM() {
-    try {
-      return KerberosUtil.getDefaultRealm();
-      // JDK7
-    } catch (ClassNotFoundException ignored) {
-      // ignored
-    } catch (NoSuchMethodException ignored) {
-      // ignored
-    } catch (IllegalAccessException ignored) {
-      // ignored
-    } catch (InvocationTargetException ignored) {
-      // ignored
+    String realm = KerberosUtil.getDefaultRealmProtected();
+    if (realm == null) {
+      realm = "";
     }
-    return "";
+    return realm;
   }
 
   /**