bbb6e126b1
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.
49 lines
1.7 KiB
Java
49 lines
1.7 KiB
Java
/*
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* Copyright 2015 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 java.net.InetSocketAddress;
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import java.util.List;
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import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
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final class RotationalDnsServerAddresses extends DefaultDnsServerAddresses {
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private static final AtomicIntegerFieldUpdater<RotationalDnsServerAddresses> startIdxUpdater =
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AtomicIntegerFieldUpdater.newUpdater(RotationalDnsServerAddresses.class, "startIdx");
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@SuppressWarnings("UnusedDeclaration")
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private volatile int startIdx;
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RotationalDnsServerAddresses(List<InetSocketAddress> addresses) {
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super("rotational", addresses);
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}
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@Override
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public DnsServerAddressStream stream() {
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for (;;) {
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int curStartIdx = startIdx;
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int nextStartIdx = curStartIdx + 1;
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if (nextStartIdx >= addresses.size()) {
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nextStartIdx = 0;
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}
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if (startIdxUpdater.compareAndSet(this, curStartIdx, nextStartIdx)) {
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return new SequentialDnsServerAddressStream(addresses, curStartIdx);
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}
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}
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}
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}
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