Class InetAddresses

guava/src/com/google/common/net/InetAddresses.java:104–1244

Static utility methods pertaining to {@link InetAddress} instances. <p><b>Important note:</b> Unlike {@code InetAddress.getByName()}, the methods of this class never cause DNS services to be accessed. For this reason, you should prefer these methods as much as possible over their JDK equivalents wh

 * @since 5.0
 */
@J2ktIncompatible
@GwtIncompatible
public final class InetAddresses {
  private static final int IPV4_PART_COUNT = 4;
  private static final int IPV6_PART_COUNT = 8;
  private static final char IPV4_DELIMITER = '.';
  private static final char IPV6_DELIMITER = ':';
  private static final CharMatcher IPV4_DELIMITER_MATCHER = CharMatcher.is(IPV4_DELIMITER);
  private static final CharMatcher IPV6_DELIMITER_MATCHER = CharMatcher.is(IPV6_DELIMITER);
  private static final Inet4Address LOOPBACK4 = (Inet4Address) forString("127.0.0.1");
  private static final Inet4Address ANY4 = (Inet4Address) forString("0.0.0.0");

  private InetAddresses() {}

  /**
   * Returns an {@link Inet4Address}, given a byte array representation of the IPv4 address.
   *
   * @param bytes byte array representing an IPv4 address (should be of length 4)
   * @return {@link Inet4Address} corresponding to the supplied byte array
   * @throws IllegalArgumentException if a valid {@link Inet4Address} can not be created
   */
  private static Inet4Address getInet4Address(byte[] bytes) {
    checkArgument(
        bytes.length == 4,
        "Byte array has invalid length for an IPv4 address: %s != 4.",
        bytes.length);

    // Given a 4-byte array, this cast should always succeed.
    return (Inet4Address) bytesToInetAddress(bytes, null);
  }

  /**
   * Returns the {@link InetAddress} having the given string representation.
   *
   * <p>This deliberately avoids all nameservice lookups (e.g. no DNS).
   *
   * <p>IPv4-mapped IPv6 addresses (e.g. {@code "::ffff:192.168.0.1"}) are returned as {@link
   * Inet4Address} objects, not {@link Inet6Address}. This is consistent with the behavior of {@link
   * InetAddress}.
   *
   * <p>This method accepts non-ASCII digits, for example {@code "１９２.１６８.０.１"} (those are fullwidth
   * characters). That is consistent with {@link InetAddress}, but not with various RFCs. If you
   * want to accept ASCII digits only, you can use something like {@code
   * CharMatcher.ascii().matchesAllOf(ipString)}.
   *
   * <p>The scope ID is validated against the interfaces on the machine, which requires permissions
   * under Android.
   *
   * <p><b>Android users on API >= 29:</b> Prefer {@code InetAddresses.parseNumericAddress}.
   *
   * @param ipString {@code String} containing an IPv4 or IPv6 string literal, e.g. {@code
   *     "192.168.0.1"} or {@code "2001:db8::1"} or with a scope ID, e.g. {@code "2001:db8::1%eth0"}
   * @return {@link InetAddress} representing the argument
   * @throws IllegalArgumentException if the argument is not a valid IP string literal or if the
   *     address has a scope ID that fails validation against the interfaces on the machine (as
   *     required by Java's {@link InetAddress})
   */
  @CanIgnoreReturnValue // TODO(b/219820829): consider removing