content: /*
   * Copyright (C) 2016 The Android Open Source Project
   *
   * Licensed 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
   *
   *      http://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 android.net.util;
  
  /**
   * Networking protocol constants.
   *
   * Includes:
   *     - constants that describe packet layout
   *     - various helper functions
   *
   * @hide
   */
  public final class NetworkConstants {
      private NetworkConstants() { throw new RuntimeException("no instance permitted"); }
  
      public static final byte FF = asByte(0xff);
      public static final byte[] ETHER_ADDR_BROADCAST = {
          FF, FF, FF, FF, FF, FF
      };
  
      public static final int ETHER_MTU = 1500;
  
      /**
       * IPv4 constants.
       *
       * See also:
       *     - https://tools.ietf.org/html/rfc791
       */
      public static final int IPV4_ADDR_BITS = 32;
  
      /**
       * IPv6 constants.
       *
       * See also:
       *     - https://tools.ietf.org/html/rfc2460
       */
      public static final int IPV6_ADDR_BITS = 128;
      public static final int IPV6_ADDR_LEN = 16;
      public static final int IPV6_MIN_MTU = 1280;
      public static final int RFC7421_PREFIX_LENGTH = 64;
  
      /**
       * ICMP common (v4/v6) constants.
       *
       * See also:
       *     - https://tools.ietf.org/html/rfc792
       *     - https://tools.ietf.org/html/rfc4443
       */
      public static final int ICMP_HEADER_TYPE_OFFSET = 0;
      public static final int ICMP_HEADER_CODE_OFFSET = 1;
      public static final int ICMP_HEADER_CHECKSUM_OFFSET = 2;
      public static final int ICMP_ECHO_IDENTIFIER_OFFSET = 4;
      public static final int ICMP_ECHO_SEQUENCE_NUMBER_OFFSET = 6;
      public static final int ICMP_ECHO_DATA_OFFSET = 8;
  
      /**
       * ICMPv4 constants.
       *
       * See also:
       *     - https://tools.ietf.org/html/rfc792
       */
      public static final int ICMPV4_ECHO_REQUEST_TYPE = 8;
      public static final int ICMPV6_ECHO_REQUEST_TYPE = 128;
  
      /**
       * DNS constants.
       *
       * See also:
       *     - https://tools.ietf.org/html/rfc1035
       */
      public static final int DNS_SERVER_PORT = 53;
  
      /**
       * Utility functions.
       */
      public static byte asByte(int i) { return (byte) i; }
  }
  