cd4594d292
* Add DnsNameResolver.resolveAll(DnsQuestion)
Motivation:
A user is currently expected to use DnsNameResolver.query() when he or
she wants to look up the full DNS records rather than just InetAddres.
However, query() only performs a single query. It does not handle
/etc/hosts file, redirection, CNAMEs or multiple name servers.
As a result, such a user has to duplicate all the logic in
DnsNameResolverContext.
Modifications:
- Refactor DnsNameResolverContext so that it can send queries for
arbitrary record types.
- Rename DnsNameResolverContext to DnsResolveContext
- Add DnsAddressResolveContext which extends DnsResolveContext for
A/AAAA lookup
- Add DnsRecordResolveContext which extends DnsResolveContext for
arbitrary lookup
- Add DnsNameResolverContext.resolveAll(DnsQuestion) and its variants
- Change DnsNameResolverContext.resolve() delegates the resolve request
to resolveAll() for simplicity
- Move the code that decodes A/AAAA record content to DnsAddressDecoder
Result:
- Fixes #7795
- A user does not have to duplicate DnsNameResolverContext in his or her
own code to implement the usual DNS resolver behavior.
68 lines
2.3 KiB
Java
68 lines
2.3 KiB
Java
/*
|
|
* Copyright 2018 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 java.net.IDN;
|
|
import java.net.InetAddress;
|
|
import java.net.UnknownHostException;
|
|
|
|
import io.netty.buffer.ByteBuf;
|
|
import io.netty.buffer.ByteBufHolder;
|
|
import io.netty.handler.codec.dns.DnsRawRecord;
|
|
import io.netty.handler.codec.dns.DnsRecord;
|
|
|
|
/**
|
|
* Decodes an {@link InetAddress} from an A or AAAA {@link DnsRawRecord}.
|
|
*/
|
|
final class DnsAddressDecoder {
|
|
|
|
private static final int INADDRSZ4 = 4;
|
|
private static final int INADDRSZ6 = 16;
|
|
|
|
/**
|
|
* Decodes an {@link InetAddress} from an A or AAAA {@link DnsRawRecord}.
|
|
*
|
|
* @param record the {@link DnsRecord}, most likely a {@link DnsRawRecord}
|
|
* @param name the host name of the decoded address
|
|
* @param decodeIdn whether to convert {@code name} to a unicode host name
|
|
*
|
|
* @return the {@link InetAddress}, or {@code null} if {@code record} is not a {@link DnsRawRecord} or
|
|
* its content is malformed
|
|
*/
|
|
static InetAddress decodeAddress(DnsRecord record, String name, boolean decodeIdn) {
|
|
if (!(record instanceof DnsRawRecord)) {
|
|
return null;
|
|
}
|
|
final ByteBuf content = ((ByteBufHolder) record).content();
|
|
final int contentLen = content.readableBytes();
|
|
if (contentLen != INADDRSZ4 && contentLen != INADDRSZ6) {
|
|
return null;
|
|
}
|
|
|
|
final byte[] addrBytes = new byte[contentLen];
|
|
content.getBytes(content.readerIndex(), addrBytes);
|
|
|
|
try {
|
|
return InetAddress.getByAddress(decodeIdn ? IDN.toUnicode(name) : name, addrBytes);
|
|
} catch (UnknownHostException e) {
|
|
// Should never reach here.
|
|
throw new Error(e);
|
|
}
|
|
}
|
|
|
|
private DnsAddressDecoder() { }
|
|
}
|