--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.dns.client/share/classes/jdk/dns/client/internal/ResourceClassType.java	Thu Oct 31 16:16:21 2019 +0000
@@ -0,0 +1,146 @@
+/*
+ * Copyright (c) 2019, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package jdk.dns.client.internal;
+
+import jdk.dns.client.AddressFamily;
+import jdk.dns.client.ex.DnsInvalidAttributeIdentifierException;
+
+public class ResourceClassType {
+    int rrclass;
+    int rrtype;
+
+    ResourceClassType(int rrtype) {
+        this.rrclass = ResourceRecord.CLASS_INTERNET;
+        this.rrtype = rrtype;
+    }
+
+    public int getRecordClass() {
+        return rrclass;
+    }
+
+    public int getRecordType() {
+        return rrtype;
+    }
+
+    public static ResourceClassType fromAddressFamily(AddressFamily addressFamily) {
+        ResourceClassType[] cts;
+        try {
+            cts = ResourceClassType.attrIdsToClassesAndTypes(typeFromAddressFamily(addressFamily));
+        } catch (DnsInvalidAttributeIdentifierException e) {
+            return new ResourceClassType(ResourceRecord.QTYPE_STAR);
+        }
+        return ResourceClassType.getClassAndTypeToQuery(cts);
+    }
+
+    private static String[] typeFromAddressFamily(AddressFamily addressFamily) {
+        switch (addressFamily) {
+            case IPv4:
+                return new String[]{"A", "CNAME"};
+            case IPv6:
+                return new String[]{"AAAA", "CNAME"};
+            default:
+                return new String[]{"A", "AAAA", "CNAME"};
+        }
+    }
+
+
+    public static ResourceClassType[] attrIdsToClassesAndTypes(String[] attrIds)
+            throws DnsInvalidAttributeIdentifierException {
+        if (attrIds == null) {
+            return null;
+        }
+        ResourceClassType[] cts = new ResourceClassType[attrIds.length];
+
+        for (int i = 0; i < attrIds.length; i++) {
+            cts[i] = fromAttrId(attrIds[i]);
+        }
+        return cts;
+    }
+
+    private static ResourceClassType fromAttrId(String attrId)
+            throws DnsInvalidAttributeIdentifierException {
+
+        if (attrId.isEmpty()) {
+            throw new DnsInvalidAttributeIdentifierException(
+                    "Attribute ID cannot be empty");
+        }
+        int rrclass;
+        int rrtype;
+        int space = attrId.indexOf(' ');
+
+        // class
+        if (space < 0) {
+            rrclass = ResourceRecord.CLASS_INTERNET;
+        } else {
+            String className = attrId.substring(0, space);
+            rrclass = ResourceRecord.getRrclass(className);
+            if (rrclass < 0) {
+                throw new DnsInvalidAttributeIdentifierException(
+                        "Unknown resource record class '" + className + '\'');
+            }
+        }
+
+        // type
+        String typeName = attrId.substring(space + 1);
+        rrtype = ResourceRecord.getType(typeName);
+        if (rrtype < 0) {
+            throw new DnsInvalidAttributeIdentifierException(
+                    "Unknown resource record type '" + typeName + '\'');
+        }
+
+        return new ResourceClassType(rrtype);
+    }
+
+    /*
+     * Returns the most restrictive resource record class and type
+     * that may be used to query for records matching cts.
+     * See classAndTypeMatch() for matching rules.
+     */
+    public static ResourceClassType getClassAndTypeToQuery(ResourceClassType[] cts) {
+        int rrclass;
+        int rrtype;
+
+        if (cts == null) {
+            // Query all records.
+            throw new RuntimeException("Internal DNS resolver error");
+        } else if (cts.length == 0) {
+            // No records are requested, but we need to ask for something.
+            rrtype = ResourceRecord.QTYPE_STAR;
+        } else {
+            rrclass = ResourceRecord.CLASS_INTERNET;
+            rrtype = cts[0].rrtype;
+            for (int i = 1; i < cts.length; i++) {
+                if (rrclass != cts[i].rrclass) {
+                    throw new RuntimeException("Internal error: Only CLASS_INTERNET is supported");
+                }
+                if (rrtype != cts[i].rrtype) {
+                    rrtype = ResourceRecord.QTYPE_STAR;
+                }
+            }
+        }
+        return new ResourceClassType(rrtype);
+    }
+}