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Add asynchronous DNS query API in Java

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DnsResolver for asynchronous DNS querying
DnsPacket for parsing answer

Test: built, flashed, booted
      atest DnsResolverTest
      atest DnsPacketTest

Change-Id: Id014bc7387dd940cfaa270f68e7d4d85fab320a0
This commit is contained in:
Luke Huang
2019-01-04 19:56:29 +08:00
parent 4e5831aecc
commit 6d23e740f8
1 changed files with 289 additions and 0 deletions
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289
core/java/android/net/DnsResolver.java Normal file
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/*
* Copyright (C) 2019 The Android Open Source Project
*
* Licensed 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 android.net;
import static android.net.NetworkUtils.resNetworkQuery;
import static android.net.NetworkUtils.resNetworkResult;
import static android.net.NetworkUtils.resNetworkSend;
import static android.os.MessageQueue.OnFileDescriptorEventListener.EVENT_ERROR;
import static android.os.MessageQueue.OnFileDescriptorEventListener.EVENT_INPUT;
import android.annotation.IntDef;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.os.Handler;
import android.os.MessageQueue;
import android.system.ErrnoException;
import android.util.Log;
import java.io.FileDescriptor;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.List;
import java.util.function.Consumer;
/**
* Dns resolver class for asynchronous dns querying
*
*/
public final class DnsResolver {
private static final String TAG = "DnsResolver";
private static final int FD_EVENTS = EVENT_INPUT | EVENT_ERROR;
private static final int MAXPACKET = 8 * 1024;
@IntDef(prefix = { "CLASS_" }, value = {
CLASS_IN
})
@Retention(RetentionPolicy.SOURCE)
@interface QueryClass {}
public static final int CLASS_IN = 1;
@IntDef(prefix = { "TYPE_" }, value = {
TYPE_A,
TYPE_AAAA
})
@Retention(RetentionPolicy.SOURCE)
@interface QueryType {}
public static final int TYPE_A = 1;
public static final int TYPE_AAAA = 28;
@IntDef(prefix = { "FLAG_" }, value = {
FLAG_EMPTY,
FLAG_NO_RETRY,
FLAG_NO_CACHE_STORE,
FLAG_NO_CACHE_LOOKUP
})
@Retention(RetentionPolicy.SOURCE)
@interface QueryFlag {}
public static final int FLAG_EMPTY = 0;
public static final int FLAG_NO_RETRY = 1 << 0;
public static final int FLAG_NO_CACHE_STORE = 1 << 1;
public static final int FLAG_NO_CACHE_LOOKUP = 1 << 2;
private static final int DNS_RAW_RESPONSE = 1;
private static final int NETID_UNSET = 0;
private static final DnsResolver sInstance = new DnsResolver();
/**
* listener for receiving raw answers
*/
public interface RawAnswerListener {
/**
* {@code byte[]} is {@code null} if query timed out
*/
void onAnswer(@Nullable byte[] answer);
}
/**
* listener for receiving parsed answers
*/
public interface InetAddressAnswerListener {
/**
* Will be called exactly once with all the answers to the query.
* size of addresses will be zero if no available answer could be parsed.
*/
void onAnswer(@NonNull List<InetAddress> addresses);
}
/**
* Get instance for DnsResolver
*/
public static DnsResolver getInstance() {
return sInstance;
}
private DnsResolver() {}
/**
* Pass in a blob and corresponding setting,
* get a blob back asynchronously with the entire raw answer.
*
* @param network {@link Network} specifying which network for querying.
* {@code null} for query on default network.
* @param query blob message
* @param flags flags as a combination of the FLAGS_* constants
* @param handler {@link Handler} to specify the thread
* upon which the {@link RawAnswerListener} will be invoked.
* @param listener a {@link RawAnswerListener} which will be called to notify the caller
* of the result of dns query.
*/
public void query(@Nullable Network network, @NonNull byte[] query, @QueryFlag int flags,
@NonNull Handler handler, @NonNull RawAnswerListener listener) throws ErrnoException {
final FileDescriptor queryfd = resNetworkSend((network != null
? network.netId : NETID_UNSET), query, query.length, flags);
registerFDListener(handler.getLooper().getQueue(), queryfd,
answerbuf -> listener.onAnswer(answerbuf));
}
/**
* Pass in a domain name and corresponding setting,
* get a blob back asynchronously with the entire raw answer.
*
* @param network {@link Network} specifying which network for querying.
* {@code null} for query on default network.
* @param domain domain name for querying
* @param nsClass dns class as one of the CLASS_* constants
* @param nsType dns resource record (RR) type as one of the TYPE_* constants
* @param flags flags as a combination of the FLAGS_* constants
* @param handler {@link Handler} to specify the thread
* upon which the {@link RawAnswerListener} will be invoked.
* @param listener a {@link RawAnswerListener} which will be called to notify the caller
* of the result of dns query.
*/
public void query(@Nullable Network network, @NonNull String domain, @QueryClass int nsClass,
@QueryType int nsType, @QueryFlag int flags,
@NonNull Handler handler, @NonNull RawAnswerListener listener) throws ErrnoException {
final FileDescriptor queryfd = resNetworkQuery((network != null
? network.netId : NETID_UNSET), domain, nsClass, nsType, flags);
registerFDListener(handler.getLooper().getQueue(), queryfd,
answerbuf -> listener.onAnswer(answerbuf));
}
/**
* Pass in a domain name and corresponding setting,
* get back a set of InetAddresses asynchronously.
*
* @param network {@link Network} specifying which network for querying.
* {@code null} for query on default network.
* @param domain domain name for querying
* @param flags flags as a combination of the FLAGS_* constants
* @param handler {@link Handler} to specify the thread
* upon which the {@link InetAddressAnswerListener} will be invoked.
* @param listener an {@link InetAddressAnswerListener} which will be called to
* notify the caller of the result of dns query.
*
*/
public void query(@Nullable Network network, @NonNull String domain, @QueryFlag int flags,
@NonNull Handler handler, @NonNull InetAddressAnswerListener listener)
throws ErrnoException {
final FileDescriptor v4fd = resNetworkQuery((network != null
? network.netId : NETID_UNSET), domain, CLASS_IN, TYPE_A, flags);
final FileDescriptor v6fd = resNetworkQuery((network != null
? network.netId : NETID_UNSET), domain, CLASS_IN, TYPE_AAAA, flags);
final InetAddressAnswerAccumulator accmulator =
new InetAddressAnswerAccumulator(2, listener);
final Consumer<byte[]> consumer = answerbuf ->
accmulator.accumulate(parseAnswers(answerbuf));
registerFDListener(handler.getLooper().getQueue(), v4fd, consumer);
registerFDListener(handler.getLooper().getQueue(), v6fd, consumer);
}
private void registerFDListener(@NonNull MessageQueue queue,
@NonNull FileDescriptor queryfd, @NonNull Consumer<byte[]> answerConsumer) {
queue.addOnFileDescriptorEventListener(
queryfd,
FD_EVENTS,
(fd, events) -> {
byte[] answerbuf = null;
try {
// TODO: Implement result function in Java side instead of using JNI
// Because JNI method close fd prior than unregistering fd on
// event listener.
answerbuf = resNetworkResult(fd);
} catch (ErrnoException e) {
Log.e(TAG, "resNetworkResult:" + e.toString());
}
answerConsumer.accept(answerbuf);
// Unregister this fd listener
return 0;
});
}
private class DnsAddressAnswer extends DnsPacket {
private static final String TAG = "DnsResolver.DnsAddressAnswer";
private static final boolean DBG = false;
private final int mQueryType;
DnsAddressAnswer(@NonNull byte[] data) throws ParseException {
super(data);
if ((mHeader.flags & (1 << 15)) == 0) {
throw new ParseException("Not an answer packet");
}
if (mHeader.rcode != 0) {
throw new ParseException("Response error, rcode:" + mHeader.rcode);
}
if (mHeader.getSectionCount(ANSECTION) == 0) {
throw new ParseException("No available answer");
}
if (mHeader.getSectionCount(QDSECTION) == 0) {
throw new ParseException("No question found");
}
// Assume only one question per answer packet. (RFC1035)
mQueryType = mSections[QDSECTION].get(0).nsType;
}
public @NonNull List<InetAddress> getAddresses() {
final List<InetAddress> results = new ArrayList<InetAddress>();
for (final DnsSection ansSec : mSections[ANSECTION]) {
// Only support A and AAAA, also ignore answers if query type != answer type.
int nsType = ansSec.nsType;
if (nsType != mQueryType || (nsType != TYPE_A && nsType != TYPE_AAAA)) {
continue;
}
try {
results.add(InetAddress.getByAddress(ansSec.getRR()));
} catch (UnknownHostException e) {
if (DBG) {
Log.w(TAG, "rr to address fail");
}
}
}
return results;
}
}
private @Nullable List<InetAddress> parseAnswers(@Nullable byte[] data) {
try {
return (data == null) ? null : new DnsAddressAnswer(data).getAddresses();
} catch (DnsPacket.ParseException e) {
Log.e(TAG, "Parse answer fail " + e.getMessage());
return null;
}
}
private class InetAddressAnswerAccumulator {
private final List<InetAddress> mAllAnswers;
private final InetAddressAnswerListener mAnswerListener;
private final int mTargetAnswerCount;
private int mReceivedAnswerCount = 0;
InetAddressAnswerAccumulator(int size, @NonNull InetAddressAnswerListener listener) {
mTargetAnswerCount = size;
mAllAnswers = new ArrayList<>();
mAnswerListener = listener;
}
public void accumulate(@Nullable List<InetAddress> answer) {
if (null != answer) {
mAllAnswers.addAll(answer);
}
if (++mReceivedAnswerCount == mTargetAnswerCount) {
mAnswerListener.onAnswer(mAllAnswers);
}
}
}
}