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   /*
    * Copyright 2016 The Netty Project
    *
    * The Netty Project licenses this file to you under the Apache License,
    * version 2.0 (the "License"); you may not use this file except in compliance
    * with the License. You may obtain a copy of the License at:
    *
    *   https://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   * License for the specific language governing permissions and limitations
   * under the License.
   */
  package io.netty.handler.codec.dns;
  
  import io.netty.util.internal.StringUtil;
  import io.netty.util.internal.UnstableApi;
  
  /**
   * An <a href="https://tools.ietf.org/html/rfc6891#section-6.1">OPT RR</a> record.
   *
   * This is used for <a href="https://tools.ietf.org/html/rfc6891#section-6.1.3">
   *     Extension Mechanisms for DNS (EDNS(0))</a>.
   */
  @UnstableApi
  public abstract class AbstractDnsOptPseudoRrRecord extends AbstractDnsRecord implements DnsOptPseudoRecord {
  
      protected AbstractDnsOptPseudoRrRecord(int maxPayloadSize, int extendedRcode, int version) {
          super(StringUtil.EMPTY_STRING, DnsRecordType.OPT, maxPayloadSize, packIntoLong(extendedRcode, version));
      }
  
      protected AbstractDnsOptPseudoRrRecord(int maxPayloadSize) {
          super(StringUtil.EMPTY_STRING, DnsRecordType.OPT, maxPayloadSize, 0);
      }
  
      // See https://tools.ietf.org/html/rfc6891#section-6.1.3
      private static long packIntoLong(int val, int val2) {
          // We are currently not support DO and Z fields, just use 0.
          return ((val & 0xffL) << 24 | (val2 & 0xff) << 16) & 0xFFFFFFFFL;
      }
  
      @Override
      public int extendedRcode() {
          return (short) (((int) timeToLive() >> 24) & 0xff);
      }
  
      @Override
      public int version() {
          return (short) (((int) timeToLive() >> 16) & 0xff);
      }
  
      @Override
      public int flags() {
         return (short) ((short) timeToLive() & 0xff);
      }
  
      @Override
      public String toString() {
          return toStringBuilder().toString();
      }
  
      final StringBuilder toStringBuilder() {
          return new StringBuilder(64)
                  .append(StringUtil.simpleClassName(this))
                  .append('(')
                  .append("OPT flags:")
                  .append(flags())
                  .append(" version:")
                  .append(version())
                  .append(" extendedRecode:")
                  .append(extendedRcode())
                  .append(" udp:")
                  .append(dnsClass())
                  .append(')');
      }
  }