/*
* Copyright 2017 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package io.netty.resolver.dns;
import io.netty.util.internal.UnstableApi;
/**
* Provides an opportunity to override which {@link DnsServerAddressStream} is used to resolve a specific hostname.
* <p>
* For example this can be used to represent <a href="https://linux.die.net/man/5/resolver">/etc/resolv.conf</a> and
* <a href="https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPages/man5/resolver.5.html">
* /etc/resolver</a>.
*/
@UnstableApi
public interface DnsServerAddressStreamProvider {
/**
* Ask this provider for the name servers to query for {@code hostname}.
* @param hostname The hostname for which to lookup the DNS server addressed to use.
* If this is the final {@link DnsServerAddressStreamProvider} to be queried then generally empty
* string or {@code '.'} correspond to the default {@link DnsServerAddressStream}.
* @return The {@link DnsServerAddressStream} which should be used to resolve {@code hostname}.
*/
DnsServerAddressStream nameServerAddressStream(String hostname);
}