Java Code Examples for io.netty.handler.codec.dns.DnsRecord#type()

private static Map<String, String> buildAliasMap(DnsResponse response) {
    final int answerCount = response.count(DnsSection.ANSWER);
    Map<String, String> cnames = null;
    for (int i = 0; i < answerCount; i ++) {
        final DnsRecord r = response.recordAt(DnsSection.ANSWER, i);
        final DnsRecordType type = r.type();
        if (type != DnsRecordType.CNAME) {
            continue;
        }

        if (!(r instanceof DnsRawRecord)) {
            continue;
        }

        final ByteBuf recordContent = ((ByteBufHolder) r).content();
        final String domainName = decodeDomainName(recordContent);
        if (domainName == null) {
            continue;
        }

        if (cnames == null) {
            cnames = new HashMap<String, String>(min(8, answerCount));
        }

        cnames.put(r.name().toLowerCase(Locale.US), domainName.toLowerCase(Locale.US));
    }

    return cnames != null? cnames : Collections.<String, String>emptyMap();
}
 

@Nullable
public static byte[] extractAddressBytes(DnsRecord record, Logger logger, String logPrefix) {
    final DnsRecordType type = record.type();
    final ByteBuf content = ((ByteBufHolder) record).content();
    final int contentLen = content.readableBytes();

    // Skip invalid records.
    if (type == DnsRecordType.A) {
        if (contentLen != 4) {
            warnInvalidRecord(logger, logPrefix, type, content);
            return null;
        }
    } else if (type == DnsRecordType.AAAA) {
        if (contentLen != 16) {
            warnInvalidRecord(logger, logPrefix, type, content);
            return null;
        }
    } else {
        return null;
    }

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

@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
    if (msg instanceof DatagramDnsQuery) {
        final DatagramDnsQuery dnsQuery = (DatagramDnsQuery) msg;
        final DnsRecord dnsRecord = dnsQuery.recordAt(DnsSection.QUESTION, 0);
        if (dnsRecord.type() == delayType) {
            ctx.executor().schedule(() -> {
                try {
                    super.channelRead(ctx, msg);
                } catch (Exception ignore) {
                }
            }, 1, TimeUnit.SECONDS);
            return;
        }
    }
    super.channelRead(ctx, msg);
}
 

@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
    if (msg instanceof DatagramDnsQuery) {
        final DatagramDnsQuery dnsQuery = (DatagramDnsQuery) msg;
        final DnsRecord dnsRecord = dnsQuery.recordAt(DnsSection.QUESTION, 0);
        if (dnsRecord.type() == A && recordACount++ == 0) {
            // Just release the msg and return so that the client request is timed out.
            ReferenceCountUtil.safeRelease(msg);
            return;
        }
    }
    super.channelRead(ctx, msg);
}
 

/**
 * Handles a redirect answer if needed and returns {@code true} if a redirect query has been made.
 */
private boolean handleRedirect(
        DnsQuestion question, AddressedEnvelope<DnsResponse, InetSocketAddress> envelope,
        final DnsQueryLifecycleObserver queryLifecycleObserver, Promise<T> promise) {
    final DnsResponse res = envelope.content();

    // Check if we have answers, if not this may be an non authority NS and so redirects must be handled.
    if (res.count(DnsSection.ANSWER) == 0) {
        AuthoritativeNameServerList serverNames = extractAuthoritativeNameServers(question.name(), res);

        if (serverNames != null) {
            List<InetSocketAddress> nameServers = new ArrayList<InetSocketAddress>(serverNames.size());
            int additionalCount = res.count(DnsSection.ADDITIONAL);

            for (int i = 0; i < additionalCount; i++) {
                final DnsRecord r = res.recordAt(DnsSection.ADDITIONAL, i);

                if (r.type() == DnsRecordType.A && !parent.supportsARecords() ||
                    r.type() == DnsRecordType.AAAA && !parent.supportsAAAARecords()) {
                    continue;
                }

                final String recordName = r.name();
                AuthoritativeNameServer authoritativeNameServer =
                        serverNames.remove(recordName);

                if (authoritativeNameServer == null) {
                    // Not a server we are interested in.
                    continue;
                }

                InetAddress resolved = parseAddress(r, recordName);
                if (resolved == null) {
                    // Could not parse it, move to the next.
                    continue;
                }

                nameServers.add(new InetSocketAddress(resolved, parent.dnsRedirectPort(resolved)));
                addNameServerToCache(authoritativeNameServer, resolved, r.timeToLive());
            }

            if (!nameServers.isEmpty()) {
                query(parent.uncachedRedirectDnsServerStream(nameServers), 0, question,
                      queryLifecycleObserver.queryRedirected(unmodifiableList(nameServers)), promise, null);
                return true;
            }
        }
    }
    return false;
}
 

void add(DnsRecord r) {
    if (r.type() != DnsRecordType.NS || !(r instanceof DnsRawRecord)) {
        return;
    }

    // Only include servers that serve the correct domain.
    if (questionName.length() <  r.name().length()) {
        return;
    }

    String recordName = r.name().toLowerCase(Locale.US);

    int dots = 0;
    for (int a = recordName.length() - 1, b = questionName.length() - 1; a >= 0; a--, b--) {
        char c = recordName.charAt(a);
        if (questionName.charAt(b) != c) {
            return;
        }
        if (c == '.') {
            dots++;
        }
    }

    if (head != null && head.dots > dots) {
        // We already have a closer match so ignore this one, no need to parse the domainName etc.
        return;
    }

    final ByteBuf recordContent = ((ByteBufHolder) r).content();
    final String domainName = decodeDomainName(recordContent);
    if (domainName == null) {
        // Could not be parsed, ignore.
        return;
    }

    // We are only interested in preserving the nameservers which are the closest to our qName, so ensure
    // we drop servers that have a smaller dots count.
    if (head == null || head.dots < dots) {
        count = 1;
        head = new AuthoritativeNameServer(dots, recordName, domainName);
    } else if (head.dots == dots) {
        AuthoritativeNameServer serverName = head;
        while (serverName.next != null) {
            serverName = serverName.next;
        }
        serverName.next = new AuthoritativeNameServer(dots, recordName, domainName);
        count++;
    }
}
 

@Override
ImmutableSortedSet<Endpoint> onDnsRecords(List<DnsRecord> records, int ttl) throws Exception {
    final ImmutableSortedSet.Builder<Endpoint> builder = ImmutableSortedSet.naturalOrder();
    for (DnsRecord r : records) {
        if (!(r instanceof DnsRawRecord) || r.type() != DnsRecordType.TXT) {
            continue;
        }

        final ByteBuf content = ((ByteBufHolder) r).content();
        if (!content.isReadable()) { // Missing length octet
            warnInvalidRecord(DnsRecordType.TXT, content);
            continue;
        }

        content.markReaderIndex();
        final int txtLen = content.readUnsignedByte();
        if (txtLen == 0) { // Empty content
            continue;
        }

        if (content.readableBytes() != txtLen) { // Mismatching number of octets
            content.resetReaderIndex();
            warnInvalidRecord(DnsRecordType.TXT, content);
            continue;
        }

        final byte[] txt = new byte[txtLen];
        content.readBytes(txt);

        final Endpoint endpoint;
        try {
            endpoint = mapping.apply(txt);
        } catch (Exception e) {
            content.resetReaderIndex();
            warnInvalidRecord(DnsRecordType.TXT, content);
            continue;
        }

        if (endpoint != null) {
            builder.add(endpoint);
        }
    }

    final ImmutableSortedSet<Endpoint> endpoints = builder.build();
    if (logger().isDebugEnabled()) {
        logger().debug("{} Resolved: {} (TTL: {})",
                       logPrefix(),
                       endpoints.stream().map(Object::toString).collect(Collectors.joining(", ")),
                       ttl);
    }

    return endpoints;
}
 

@Override
ImmutableSortedSet<Endpoint> onDnsRecords(List<DnsRecord> records, int ttl) throws Exception {
    final ImmutableSortedSet.Builder<Endpoint> builder = ImmutableSortedSet.naturalOrder();
    for (DnsRecord r : records) {
        if (!(r instanceof DnsRawRecord) || r.type() != DnsRecordType.SRV) {
            continue;
        }

        final ByteBuf content = ((ByteBufHolder) r).content();
        if (content.readableBytes() <= 6) { // Too few bytes
            warnInvalidRecord(DnsRecordType.SRV, content);
            continue;
        }

        content.markReaderIndex();
        content.skipBytes(2);  // priority unused
        final int weight = content.readUnsignedShort();
        final int port = content.readUnsignedShort();

        final Endpoint endpoint;
        try {
            final String target = stripTrailingDot(DefaultDnsRecordDecoder.decodeName(content));
            endpoint = port > 0 ? Endpoint.of(target, port) : Endpoint.of(target);
        } catch (Exception e) {
            content.resetReaderIndex();
            warnInvalidRecord(DnsRecordType.SRV, content);
            continue;
        }

        builder.add(endpoint.withWeight(weight));
    }

    final ImmutableSortedSet<Endpoint> endpoints = builder.build();
    if (logger().isDebugEnabled()) {
        logger().debug("{} Resolved: {} (TTL: {})",
                       logPrefix(),
                       endpoints.stream()
                                .map(e -> e.authority() + '/' + e.weight())
                                .collect(Collectors.joining(", ")),
                       ttl);
    }

    return endpoints;
}