DnsAddressDecoder Class — netty Architecture

Source Code

resolver-dns/src/main/java/io/netty/resolver/dns/DnsAddressDecoder.java lines 30–67

final class DnsAddressDecoder {

    private static final int INADDRSZ4 = 4;
    private static final int INADDRSZ6 = 16;

    /**
     * Decodes an {@link InetAddress} from an A or AAAA {@link DnsRawRecord}.
     *
     * @param record the {@link DnsRecord}, most likely a {@link DnsRawRecord}
     * @param name the host name of the decoded address
     * @param decodeIdn whether to convert {@code name} to a unicode host name
     *
     * @return the {@link InetAddress}, or {@code null} if {@code record} is not a {@link DnsRawRecord} or
     *         its content is malformed
     */
    static InetAddress decodeAddress(DnsRecord record, String name, boolean decodeIdn) {
        if (!(record instanceof DnsRawRecord)) {
            return null;
        }
        final ByteBuf content = ((ByteBufHolder) record).content();
        final int contentLen = content.readableBytes();
        if (contentLen != INADDRSZ4 && contentLen != INADDRSZ6) {
            return null;
        }

        final byte[] addrBytes = new byte[contentLen];
        content.getBytes(content.readerIndex(), addrBytes);

        try {
            return InetAddress.getByAddress(decodeIdn ? IDN.toUnicode(name) : name, addrBytes);
        } catch (UnknownHostException e) {
            // Should never reach here.
            throw new Error("Failed to decode address \"" + name + '"', e);
        }
    }

    private DnsAddressDecoder() { }
}