Motiviation: We incorrectly did ignore NS servers during redirect which had no ADDITIONAL record. This could at worse have the affect that we failed the query completely as none of the NS servers had a ADDITIONAL record. Beside this using a DnsCache to cache authoritative nameservers does not work in practise as we we need different features and semantics when cache these servers (for example we also want to cache unresolved nameservers and resolve these on the fly when needed). Modifications: - Correctly take NS records into account that have no matching ADDITIONAL record - Correctly handle multiple ADDITIONAL records for the same NS record - Introduce AuthoritativeDnsServerCache as a replacement of the DnsCache when caching authoritative nameservers + adding default implementation - Add an adapter layer to reduce API breakage as much as possible - Replace DnsNameResolver.uncachedRedirectDnsServerStream(...) with newRedirectDnsServerStream(...) - Add unit tests Result: Our DnsResolver now correctly handle redirects in all cases.
220 lines
8.3 KiB
Java
220 lines
8.3 KiB
Java
/*
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* Copyright 2014 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.resolver.dns;
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import io.netty.util.internal.UnstableApi;
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import java.net.InetSocketAddress;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.List;
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/**
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* Provides an infinite sequence of DNS server addresses to {@link DnsNameResolver}.
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*/
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@UnstableApi
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@SuppressWarnings("IteratorNextCanNotThrowNoSuchElementException")
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public abstract class DnsServerAddresses {
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/**
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* @deprecated Use {@link DefaultDnsServerAddressStreamProvider#defaultAddressList()}.
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* <p>
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* Returns the list of the system DNS server addresses. If it failed to retrieve the list of the system DNS server
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* addresses from the environment, it will return {@code "8.8.8.8"} and {@code "8.8.4.4"}, the addresses of the
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* Google public DNS servers.
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*/
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@Deprecated
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public static List<InetSocketAddress> defaultAddressList() {
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return DefaultDnsServerAddressStreamProvider.defaultAddressList();
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}
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/**
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* @deprecated Use {@link DefaultDnsServerAddressStreamProvider#defaultAddresses()}.
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* <p>
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* Returns the {@link DnsServerAddresses} that yields the system DNS server addresses sequentially. If it failed to
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* retrieve the list of the system DNS server addresses from the environment, it will use {@code "8.8.8.8"} and
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* {@code "8.8.4.4"}, the addresses of the Google public DNS servers.
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* <p>
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* This method has the same effect with the following code:
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* <pre>
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* DnsServerAddresses.sequential(DnsServerAddresses.defaultAddressList());
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* </pre>
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* </p>
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*/
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@Deprecated
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public static DnsServerAddresses defaultAddresses() {
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return DefaultDnsServerAddressStreamProvider.defaultAddresses();
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}
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/**
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* Returns the {@link DnsServerAddresses} that yields the specified {@code addresses} sequentially. Once the
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* last address is yielded, it will start again from the first address.
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*/
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public static DnsServerAddresses sequential(Iterable<? extends InetSocketAddress> addresses) {
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return sequential0(sanitize(addresses));
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}
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/**
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* Returns the {@link DnsServerAddresses} that yields the specified {@code addresses} sequentially. Once the
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* last address is yielded, it will start again from the first address.
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*/
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public static DnsServerAddresses sequential(InetSocketAddress... addresses) {
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return sequential0(sanitize(addresses));
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}
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private static DnsServerAddresses sequential0(final List<InetSocketAddress> addresses) {
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if (addresses.size() == 1) {
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return singleton(addresses.get(0));
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}
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return new DefaultDnsServerAddresses("sequential", addresses) {
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@Override
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public DnsServerAddressStream stream() {
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return new SequentialDnsServerAddressStream(addresses, 0);
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}
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};
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}
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/**
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* Returns the {@link DnsServerAddresses} that yields the specified {@code address} in a shuffled order. Once all
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* addresses are yielded, the addresses are shuffled again.
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*/
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public static DnsServerAddresses shuffled(Iterable<? extends InetSocketAddress> addresses) {
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return shuffled0(sanitize(addresses));
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}
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/**
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* Returns the {@link DnsServerAddresses} that yields the specified {@code addresses} in a shuffled order. Once all
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* addresses are yielded, the addresses are shuffled again.
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*/
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public static DnsServerAddresses shuffled(InetSocketAddress... addresses) {
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return shuffled0(sanitize(addresses));
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}
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private static DnsServerAddresses shuffled0(List<InetSocketAddress> addresses) {
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if (addresses.size() == 1) {
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return singleton(addresses.get(0));
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}
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return new DefaultDnsServerAddresses("shuffled", addresses) {
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@Override
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public DnsServerAddressStream stream() {
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return new ShuffledDnsServerAddressStream(addresses);
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}
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};
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}
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/**
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* Returns the {@link DnsServerAddresses} that yields the specified {@code addresses} in a rotational sequential
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* order. It is similar to {@link #sequential(Iterable)}, but each {@link DnsServerAddressStream} starts from
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* a different starting point. For example, the first {@link #stream()} will start from the first address, the
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* second one will start from the second address, and so on.
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*/
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public static DnsServerAddresses rotational(Iterable<? extends InetSocketAddress> addresses) {
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return rotational0(sanitize(addresses));
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}
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/**
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* Returns the {@link DnsServerAddresses} that yields the specified {@code addresses} in a rotational sequential
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* order. It is similar to {@link #sequential(Iterable)}, but each {@link DnsServerAddressStream} starts from
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* a different starting point. For example, the first {@link #stream()} will start from the first address, the
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* second one will start from the second address, and so on.
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*/
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public static DnsServerAddresses rotational(InetSocketAddress... addresses) {
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return rotational0(sanitize(addresses));
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}
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private static DnsServerAddresses rotational0(List<InetSocketAddress> addresses) {
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if (addresses.size() == 1) {
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return singleton(addresses.get(0));
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}
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return new RotationalDnsServerAddresses(addresses);
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}
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/**
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* Returns the {@link DnsServerAddresses} that yields only a single {@code address}.
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*/
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public static DnsServerAddresses singleton(final InetSocketAddress address) {
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if (address == null) {
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throw new NullPointerException("address");
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}
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if (address.isUnresolved()) {
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throw new IllegalArgumentException("cannot use an unresolved DNS server address: " + address);
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}
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return new SingletonDnsServerAddresses(address);
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}
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private static List<InetSocketAddress> sanitize(Iterable<? extends InetSocketAddress> addresses) {
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if (addresses == null) {
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throw new NullPointerException("addresses");
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}
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final List<InetSocketAddress> list;
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if (addresses instanceof Collection) {
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list = new ArrayList<InetSocketAddress>(((Collection<?>) addresses).size());
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} else {
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list = new ArrayList<InetSocketAddress>(4);
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}
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for (InetSocketAddress a : addresses) {
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if (a == null) {
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break;
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}
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if (a.isUnresolved()) {
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throw new IllegalArgumentException("cannot use an unresolved DNS server address: " + a);
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}
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list.add(a);
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}
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if (list.isEmpty()) {
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throw new IllegalArgumentException("empty addresses");
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}
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return list;
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}
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private static List<InetSocketAddress> sanitize(InetSocketAddress[] addresses) {
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if (addresses == null) {
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throw new NullPointerException("addresses");
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}
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List<InetSocketAddress> list = new ArrayList<InetSocketAddress>(addresses.length);
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for (InetSocketAddress a: addresses) {
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if (a == null) {
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break;
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}
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if (a.isUnresolved()) {
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throw new IllegalArgumentException("cannot use an unresolved DNS server address: " + a);
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}
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list.add(a);
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}
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if (list.isEmpty()) {
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return DefaultDnsServerAddressStreamProvider.defaultAddressList();
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}
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return list;
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}
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/**
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* Starts a new infinite stream of DNS server addresses. This method is invoked by {@link DnsNameResolver} on every
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* uncached {@link DnsNameResolver#resolve(String)}or {@link DnsNameResolver#resolveAll(String)}.
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*/
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public abstract DnsServerAddressStream stream();
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}
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