8175940: More certificate subject checking

Reviewed-by: ahgross, mullan

src/share/classes/sun/security/x509/DNSName.java

 /*
- * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -194,13 +194,28 @@ public class DNSName implements GeneralNameInterface {
      */
     public int constrains(GeneralNameInterface inputName) throws UnsupportedOperationException {
         int constraintType;
-        if (inputName == null)
-            constraintType = NAME_DIFF_TYPE;
-        else if (inputName.getType() != NAME_DNS)
-            constraintType = NAME_DIFF_TYPE;
-        else {
-            String inName =
-                (((DNSName)inputName).getName()).toLowerCase(Locale.ENGLISH);
+        if (inputName == null) {
+            return NAME_DIFF_TYPE;
+        }
+        String inName;
+        switch (inputName.getType()) {
+            case NAME_DNS:
+                inName = ((DNSName)inputName).getName();
+                break;
+            case NAME_DIRECTORY:
+                try {
+                    inName = ((X500Name) inputName).getCommonName();
+                    if (inName == null) {
+                        return NAME_DIFF_TYPE;
+                    }
+                } catch (IOException ioe) {
+                    return NAME_DIFF_TYPE;
+                }
+                break;
+            default:
+                return NAME_DIFF_TYPE;
+        }
+        inName = inName.toLowerCase(Locale.ENGLISH);
         String thisName = name.toLowerCase(Locale.ENGLISH);
         if (inName.equals(thisName))
             constraintType = NAME_MATCH;
@@ -219,7 +234,6 @@ public class DNSName implements GeneralNameInterface {
         } else {
             constraintType = NAME_SAME_TYPE;
         }
-        }
         return constraintType;
     }