netty5/resolver-dns/src/test/java/io/netty/resolver/dns/UnixResolverDnsServerAddressStreamProviderTest.java
Scott Mitchell 0f1a2ca5ae UnixResolverDnsServerAddressStreamProvider default name server selection and ordering bug
Motivation:
UnixResolverDnsServerAddressStreamProvider allows the default name server address stream to be null, but there should always be a default stream to fall back to ([1] Search Strategy).
UnixResolverDnsServerAddressStreamProvider currently shuffles the names servers are multiple are present, but the defined behavior is to try them sequentially [2].

[1] Search Strategy Section - https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPages/man5/resolver.5.html
[2] DESCRIPTION/nameserver Section - https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPages/man5/resolver.5.html

Modifications:
- UnixResolverDnsServerAddressStreamProvider should always use the first file provided to derive the default domain server address stream. Currently if there are multiple domain names in the file identified by the first argument of the constructor then one will be selected at random.
- UnixResolverDnsServerAddressStreamProvider should return name servers sequentially.
- Reduce access level on some methods which don't have known use-cases externally.

Result:
Fixes https://github.com/netty/netty/issues/6736
2017-05-18 15:14:58 -07:00

95 lines
3.6 KiB
Java

/*
* 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
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
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package io.netty.resolver.dns;
import io.netty.util.CharsetUtil;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TemporaryFolder;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import static org.junit.Assert.assertEquals;
public class UnixResolverDnsServerAddressStreamProviderTest {
@Rule
public final TemporaryFolder folder = new TemporaryFolder();
@Test
public void defaultLookupShouldReturnResultsIfOnlySingleFileSpecified() throws Exception {
File f = buildFile("domain linecorp.local\n" +
"nameserver 127.0.0.2\n" +
"nameserver 127.0.0.3\n");
UnixResolverDnsServerAddressStreamProvider p =
new UnixResolverDnsServerAddressStreamProvider(f, null);
DnsServerAddressStream stream = p.nameServerAddressStream("somehost");
assertHostNameEquals("127.0.0.2", stream.next());
assertHostNameEquals("127.0.0.3", stream.next());
}
@Test
public void defaultReturnedWhenNoBetterMatch() throws Exception {
File f = buildFile("domain linecorp.local\n" +
"nameserver 127.0.0.2\n" +
"nameserver 127.0.0.3\n");
File f2 = buildFile("domain squarecorp.local\n" +
"nameserver 127.0.0.4\n" +
"nameserver 127.0.0.5\n");
UnixResolverDnsServerAddressStreamProvider p =
new UnixResolverDnsServerAddressStreamProvider(f, f2);
DnsServerAddressStream stream = p.nameServerAddressStream("somehost");
assertHostNameEquals("127.0.0.2", stream.next());
assertHostNameEquals("127.0.0.3", stream.next());
}
@Test
public void moreRefinedSelectionReturnedWhenMatch() throws Exception {
File f = buildFile("domain linecorp.local\n" +
"nameserver 127.0.0.2\n" +
"nameserver 127.0.0.3\n");
File f2 = buildFile("domain dc1.linecorp.local\n" +
"nameserver 127.0.0.4\n" +
"nameserver 127.0.0.5\n");
UnixResolverDnsServerAddressStreamProvider p =
new UnixResolverDnsServerAddressStreamProvider(f, f2);
DnsServerAddressStream stream = p.nameServerAddressStream("myhost.dc1.linecorp.local");
assertHostNameEquals("127.0.0.4", stream.next());
assertHostNameEquals("127.0.0.5", stream.next());
}
private File buildFile(String contents) throws IOException {
File f = folder.newFile();
OutputStream out = new FileOutputStream(f);
try {
out.write(contents.getBytes(CharsetUtil.UTF_8));
} finally {
out.close();
}
return f;
}
private static void assertHostNameEquals(String expectedHostname, InetSocketAddress next) {
assertEquals("unexpected hostname: " + next, expectedHostname, next.getHostName());
}
}