e074df2ae6
Motivation: Recently DnsServerAddressStreamProvider was introduced to allow control for each query as to which DNS server should be used for resolution to respect the local host's default DNS server configuration. However resolver-dns also accepts a stream of DNS servers to use by default, but this stream is not host name aware. This creates an ambiguity as to which method is used to determine the DNS server to user during resolution, and in which order. We can remove this ambiguity and provide a more general API by just supporting DnsServerAddressStreamProvider. Modifications: - Remove the fixed DnsServerAddresses and instead only accept a DnsServerAddressStreamProvider. - Add utility methods to help use DnsServerAddressStreamProvider for a single entry, a list of entries, and get the default for the current machine. Result: Fixes https://github.com/netty/netty/issues/6573.
38 lines
1.7 KiB
Java
38 lines
1.7 KiB
Java
/*
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* Copyright 2017 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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/**
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* Provides an opportunity to override which {@link DnsServerAddressStream} is used to resolve a specific hostname.
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* <p>
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* For example this can be used to represent <a href="https://linux.die.net/man/5/resolver">/etc/resolv.conf</a> and
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* <a href="https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPages/man5/resolver.5.html">
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* /etc/resolver</a>.
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*/
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@UnstableApi
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public interface DnsServerAddressStreamProvider {
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/**
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* Ask this provider for the name servers to query for {@code hostname}.
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* @param hostname The hostname for which to lookup the DNS server addressed to use.
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* If this is the final {@link DnsServerAddressStreamProvider} to be queried then generally empty
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* string or {@code '.'} correspond to the default {@link DnsServerAddressStream}.
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* @return The {@link DnsServerAddressStream} which should be used to resolve {@code hostname}.
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*/
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DnsServerAddressStream nameServerAddressStream(String hostname);
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}
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