core/java/android/net/DnsResolver.java - platform/frameworks/base - Gitiles

 /*
  * 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);
             }
         }
     }
 }
	/*
	* 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);
	}
	}
	}
	}