NetUtil Class — netty Architecture

Source Code

common/src/main/java/io/netty/util/NetUtil.java lines 52–1104

public final class NetUtil {

    /**
     * The {@link Inet4Address} that represents the IPv4 loopback address '127.0.0.1'
     */
    public static final Inet4Address LOCALHOST4;

    /**
     * The {@link Inet6Address} that represents the IPv6 loopback address '::1'
     */
    public static final Inet6Address LOCALHOST6;

    /**
     * The {@link InetAddress} that represents the loopback address. If IPv6 stack is available, it will refer to
     * {@link #LOCALHOST6}.  Otherwise, {@link #LOCALHOST4}.
     */
    public static final InetAddress LOCALHOST;

    /**
     * The loopback {@link NetworkInterface} of the current machine
     */
    public static final NetworkInterface LOOPBACK_IF;

    /**
     * An unmodifiable Collection of all the interfaces on this machine.
     */
    public static final Collection<NetworkInterface> NETWORK_INTERFACES;

    /**
     * The SOMAXCONN value of the current machine.  If failed to get the value,  {@code 200} is used as a
     * default value for Windows and {@code 128} for others.
     */
    public static final int SOMAXCONN;

    /**
     * This defines how many words (represented as ints) are needed to represent an IPv6 address
     */
    private static final int IPV6_WORD_COUNT = 8;

    /**
     * The maximum number of characters for an IPV6 string with no scope
     */
    private static final int IPV6_MAX_CHAR_COUNT = 39;

    /**
     * Number of bytes needed to represent an IPV6 value
     */
    private static final int IPV6_BYTE_COUNT = 16;

    /**
     * Maximum amount of value adding characters in between IPV6 separators
     */
    private static final int IPV6_MAX_CHAR_BETWEEN_SEPARATOR = 4;

    /**
     * Minimum number of separators that must be present in an IPv6 string
     */
    private static final int IPV6_MIN_SEPARATORS = 2;

    /**
     * Maximum number of separators that must be present in an IPv6 string
     */
    private static final int IPV6_MAX_SEPARATORS = 8;

    /**
     * Maximum amount of value adding characters in between IPV4 separators
     */
    private static final int IPV4_MAX_CHAR_BETWEEN_SEPARATOR = 3;

    /**
     * Number of separators that must be present in an IPv4 string
     */
    private static final int IPV4_SEPARATORS = 3;

    /**
     * {@code true} if IPv4 should be used even if the system supports both IPv4 and IPv6.
     */
    private static final boolean IPV4_PREFERRED = SystemPropertyUtil.getBoolean("java.net.preferIPv4Stack", false);

    /**
     * {@code true} if an IPv6 address should be preferred when a host has both an IPv4 address and an IPv6 address.