| /* |
| * 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.resNetworkCancel; |
| 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 static android.system.OsConstants.AF_INET; |
| import static android.system.OsConstants.AF_INET6; |
| import static android.system.OsConstants.IPPROTO_UDP; |
| import static android.system.OsConstants.SOCK_DGRAM; |
| |
| import android.annotation.CallbackExecutor; |
| import android.annotation.IntDef; |
| import android.annotation.NonNull; |
| import android.annotation.Nullable; |
| import android.os.CancellationSignal; |
| import android.os.Looper; |
| import android.system.ErrnoException; |
| import android.system.Os; |
| import android.util.Log; |
| |
| import libcore.io.IoUtils; |
| |
| import java.io.FileDescriptor; |
| import java.io.IOException; |
| import java.lang.annotation.Retention; |
| import java.lang.annotation.RetentionPolicy; |
| import java.net.InetAddress; |
| import java.net.InetSocketAddress; |
| import java.net.SocketAddress; |
| import java.net.UnknownHostException; |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.concurrent.Executor; |
| |
| /** |
| * Dns resolver class for asynchronous dns querying |
| * |
| * Note that if a client sends a query with more than 1 record in the question section but |
| * the remote dns server does not support this, it may not respond at all, leading to a timeout. |
| * |
| */ |
| 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; |
| private static final int SLEEP_TIME_MS = 2; |
| |
| @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 NETID_UNSET = 0; |
| |
| private static final DnsResolver sInstance = new DnsResolver(); |
| |
| /** |
| * Get instance for DnsResolver |
| */ |
| public static @NonNull DnsResolver getInstance() { |
| return sInstance; |
| } |
| |
| private DnsResolver() {} |
| |
| /** |
| * Answer parser for parsing raw answers |
| * |
| * @param <T> The type of the parsed answer |
| */ |
| public interface AnswerParser<T> { |
| /** |
| * Creates a <T> answer by parsing the given raw answer. |
| * |
| * @param rawAnswer the raw answer to be parsed |
| * @return a parsed <T> answer |
| * @throws ParseException if parsing failed |
| */ |
| @NonNull T parse(@NonNull byte[] rawAnswer) throws ParseException; |
| } |
| |
| /** |
| * Base class for answer callbacks |
| * |
| * @param <T> The type of the parsed answer |
| */ |
| public abstract static class AnswerCallback<T> { |
| /** @hide */ |
| public final AnswerParser<T> parser; |
| |
| public AnswerCallback(@NonNull AnswerParser<T> parser) { |
| this.parser = parser; |
| }; |
| |
| /** |
| * Success response to |
| * {@link android.net.DnsResolver#query query()}. |
| * |
| * Invoked when the answer to a query was successfully parsed. |
| * |
| * @param answer parsed answer to the query. |
| * |
| * {@see android.net.DnsResolver#query query()} |
| */ |
| public abstract void onAnswer(@NonNull T answer); |
| |
| /** |
| * Error response to |
| * {@link android.net.DnsResolver#query query()}. |
| * |
| * Invoked when there is no valid answer to |
| * {@link android.net.DnsResolver#query query()} |
| * |
| * @param exception a {@link ParseException} object with additional |
| * detail regarding the failure |
| */ |
| public abstract void onParseException(@NonNull ParseException exception); |
| |
| /** |
| * Error response to |
| * {@link android.net.DnsResolver#query query()}. |
| * |
| * Invoked if an error happens when |
| * issuing the DNS query or receiving the result. |
| * {@link android.net.DnsResolver#query query()} |
| * |
| * @param exception an {@link ErrnoException} object with additional detail |
| * regarding the failure |
| */ |
| public abstract void onQueryException(@NonNull ErrnoException exception); |
| } |
| |
| /** |
| * Callback for receiving raw answers |
| */ |
| public abstract static class RawAnswerCallback extends AnswerCallback<byte[]> { |
| public RawAnswerCallback() { |
| super(rawAnswer -> rawAnswer); |
| } |
| } |
| |
| /** |
| * Callback for receiving parsed {@link InetAddress} answers |
| * |
| * Note that if the answer does not contain any IP addresses, |
| * onAnswer will be called with an empty list. |
| */ |
| public abstract static class InetAddressAnswerCallback |
| extends AnswerCallback<List<InetAddress>> { |
| public InetAddressAnswerCallback() { |
| super(rawAnswer -> new DnsAddressAnswer(rawAnswer).getAddresses()); |
| } |
| } |
| |
| /** |
| * Send a raw DNS query. |
| * The answer will be provided asynchronously through the provided {@link AnswerCallback}. |
| * |
| * @param network {@link Network} specifying which network to query on. |
| * {@code null} for query on default network. |
| * @param query blob message to query |
| * @param flags flags as a combination of the FLAGS_* constants |
| * @param executor The {@link Executor} that the callback should be executed on. |
| * @param cancellationSignal used by the caller to signal if the query should be |
| * cancelled. May be {@code null}. |
| * @param callback an {@link AnswerCallback} which will be called to notify the caller |
| * of the result of dns query. |
| */ |
| public <T> void query(@Nullable Network network, @NonNull byte[] query, @QueryFlag int flags, |
| @NonNull @CallbackExecutor Executor executor, |
| @Nullable CancellationSignal cancellationSignal, |
| @NonNull AnswerCallback<T> callback) { |
| if (cancellationSignal != null && cancellationSignal.isCanceled()) { |
| return; |
| } |
| final Object lock = new Object(); |
| final FileDescriptor queryfd; |
| try { |
| queryfd = resNetworkSend((network != null |
| ? network.netId : NETID_UNSET), query, query.length, flags); |
| } catch (ErrnoException e) { |
| executor.execute(() -> { |
| callback.onQueryException(e); |
| }); |
| return; |
| } |
| |
| synchronized (lock) { |
| registerFDListener(executor, queryfd, callback, cancellationSignal, lock); |
| if (cancellationSignal == null) return; |
| addCancellationSignal(cancellationSignal, queryfd, lock); |
| } |
| } |
| |
| /** |
| * Send a DNS query with the specified name, class and query type. |
| * The answer will be provided asynchronously through the provided {@link AnswerCallback}. |
| * |
| * @param network {@link Network} specifying which network to query on. |
| * {@code null} for query on default network. |
| * @param domain domain name to query |
| * @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 executor The {@link Executor} that the callback should be executed on. |
| * @param cancellationSignal used by the caller to signal if the query should be |
| * cancelled. May be {@code null}. |
| * @param callback an {@link AnswerCallback} which will be called to notify the caller |
| * of the result of dns query. |
| */ |
| public <T> void query(@Nullable Network network, @NonNull String domain, |
| @QueryClass int nsClass, @QueryType int nsType, @QueryFlag int flags, |
| @NonNull @CallbackExecutor Executor executor, |
| @Nullable CancellationSignal cancellationSignal, |
| @NonNull AnswerCallback<T> callback) { |
| if (cancellationSignal != null && cancellationSignal.isCanceled()) { |
| return; |
| } |
| final Object lock = new Object(); |
| final FileDescriptor queryfd; |
| try { |
| queryfd = resNetworkQuery((network != null |
| ? network.netId : NETID_UNSET), domain, nsClass, nsType, flags); |
| } catch (ErrnoException e) { |
| executor.execute(() -> { |
| callback.onQueryException(e); |
| }); |
| return; |
| } |
| synchronized (lock) { |
| registerFDListener(executor, queryfd, callback, cancellationSignal, lock); |
| if (cancellationSignal == null) return; |
| addCancellationSignal(cancellationSignal, queryfd, lock); |
| } |
| } |
| |
| private class InetAddressAnswerAccumulator extends InetAddressAnswerCallback { |
| private final List<InetAddress> mAllAnswers; |
| private ParseException mParseException; |
| private ErrnoException mErrnoException; |
| private final InetAddressAnswerCallback mUserCallback; |
| private final int mTargetAnswerCount; |
| private int mReceivedAnswerCount = 0; |
| |
| InetAddressAnswerAccumulator(int size, @NonNull InetAddressAnswerCallback callback) { |
| mTargetAnswerCount = size; |
| mAllAnswers = new ArrayList<>(); |
| mUserCallback = callback; |
| } |
| |
| private boolean maybeReportException() { |
| if (mErrnoException != null) { |
| mUserCallback.onQueryException(mErrnoException); |
| return true; |
| } |
| if (mParseException != null) { |
| mUserCallback.onParseException(mParseException); |
| return true; |
| } |
| return false; |
| } |
| |
| private void maybeReportAnswer() { |
| if (++mReceivedAnswerCount != mTargetAnswerCount) return; |
| if (mAllAnswers.isEmpty() && maybeReportException()) return; |
| // TODO: Do RFC6724 sort. |
| mUserCallback.onAnswer(mAllAnswers); |
| } |
| |
| @Override |
| public void onAnswer(@NonNull List<InetAddress> answer) { |
| mAllAnswers.addAll(answer); |
| maybeReportAnswer(); |
| } |
| |
| @Override |
| public void onParseException(@NonNull ParseException e) { |
| mParseException = e; |
| maybeReportAnswer(); |
| } |
| |
| @Override |
| public void onQueryException(@NonNull ErrnoException e) { |
| mErrnoException = e; |
| maybeReportAnswer(); |
| } |
| } |
| |
| /** |
| * Send a DNS query with the specified name, get back a set of InetAddresses asynchronously. |
| * The answer will be provided asynchronously through the provided |
| * {@link InetAddressAnswerCallback}. |
| * |
| * @param network {@link Network} specifying which network to query on. |
| * {@code null} for query on default network. |
| * @param domain domain name to query |
| * @param flags flags as a combination of the FLAGS_* constants |
| * @param executor The {@link Executor} that the callback should be executed on. |
| * @param cancellationSignal used by the caller to signal if the query should be |
| * cancelled. May be {@code null}. |
| * @param callback an {@link InetAddressAnswerCallback} 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 @CallbackExecutor Executor executor, |
| @Nullable CancellationSignal cancellationSignal, |
| @NonNull InetAddressAnswerCallback callback) { |
| if (cancellationSignal != null && cancellationSignal.isCanceled()) { |
| return; |
| } |
| final Object lock = new Object(); |
| final boolean queryIpv6 = haveIpv6(network); |
| final boolean queryIpv4 = haveIpv4(network); |
| |
| final FileDescriptor v4fd; |
| final FileDescriptor v6fd; |
| |
| int queryCount = 0; |
| |
| if (queryIpv6) { |
| try { |
| v6fd = resNetworkQuery((network != null |
| ? network.netId : NETID_UNSET), domain, CLASS_IN, TYPE_AAAA, flags); |
| } catch (ErrnoException e) { |
| executor.execute(() -> { |
| callback.onQueryException(e); |
| }); |
| return; |
| } |
| queryCount++; |
| } else v6fd = null; |
| |
| // TODO: Use device flag to control the sleep time. |
| // Avoiding gateways drop packets if queries are sent too close together |
| try { |
| Thread.sleep(SLEEP_TIME_MS); |
| } catch (InterruptedException ex) { } |
| |
| if (queryIpv4) { |
| try { |
| v4fd = resNetworkQuery((network != null |
| ? network.netId : NETID_UNSET), domain, CLASS_IN, TYPE_A, flags); |
| } catch (ErrnoException e) { |
| if (queryIpv6) resNetworkCancel(v6fd); // Closes fd, marks it invalid. |
| executor.execute(() -> { |
| callback.onQueryException(e); |
| }); |
| return; |
| } |
| queryCount++; |
| } else v4fd = null; |
| |
| final InetAddressAnswerAccumulator accumulator = |
| new InetAddressAnswerAccumulator(queryCount, callback); |
| |
| synchronized (lock) { |
| if (queryIpv6) { |
| registerFDListener(executor, v6fd, accumulator, cancellationSignal, lock); |
| } |
| if (queryIpv4) { |
| registerFDListener(executor, v4fd, accumulator, cancellationSignal, lock); |
| } |
| if (cancellationSignal == null) return; |
| cancellationSignal.setOnCancelListener(() -> { |
| synchronized (lock) { |
| if (queryIpv4) cancelQuery(v4fd); |
| if (queryIpv6) cancelQuery(v6fd); |
| } |
| }); |
| } |
| } |
| |
| private <T> void registerFDListener(@NonNull Executor executor, |
| @NonNull FileDescriptor queryfd, @NonNull AnswerCallback<T> answerCallback, |
| @Nullable CancellationSignal cancellationSignal, @NonNull Object lock) { |
| Looper.getMainLooper().getQueue().addOnFileDescriptorEventListener( |
| queryfd, |
| FD_EVENTS, |
| (fd, events) -> { |
| executor.execute(() -> { |
| synchronized (lock) { |
| if (cancellationSignal != null && cancellationSignal.isCanceled()) { |
| return; |
| } |
| byte[] answerbuf = null; |
| try { |
| answerbuf = resNetworkResult(fd); // Closes fd, marks it invalid. |
| } catch (ErrnoException e) { |
| Log.e(TAG, "resNetworkResult:" + e.toString()); |
| answerCallback.onQueryException(e); |
| return; |
| } |
| |
| try { |
| answerCallback.onAnswer( |
| answerCallback.parser.parse(answerbuf)); |
| } catch (ParseException e) { |
| answerCallback.onParseException(e); |
| } |
| } |
| }); |
| // Unregister this fd listener |
| return 0; |
| }); |
| } |
| |
| private void cancelQuery(@NonNull FileDescriptor queryfd) { |
| if (!queryfd.valid()) return; |
| Looper.getMainLooper().getQueue().removeOnFileDescriptorEventListener(queryfd); |
| resNetworkCancel(queryfd); // Closes fd, marks it invalid. |
| } |
| |
| private void addCancellationSignal(@NonNull CancellationSignal cancellationSignal, |
| @NonNull FileDescriptor queryfd, @NonNull Object lock) { |
| cancellationSignal.setOnCancelListener(() -> { |
| synchronized (lock) { |
| cancelQuery(queryfd); |
| } |
| }); |
| } |
| |
| // These two functions match the behaviour of have_ipv4 and have_ipv6 in the native resolver. |
| private boolean haveIpv4(@Nullable Network network) { |
| final SocketAddress addrIpv4 = |
| new InetSocketAddress(InetAddresses.parseNumericAddress("8.8.8.8"), 0); |
| return checkConnectivity(network, AF_INET, addrIpv4); |
| } |
| |
| private boolean haveIpv6(@Nullable Network network) { |
| final SocketAddress addrIpv6 = |
| new InetSocketAddress(InetAddresses.parseNumericAddress("2000::"), 0); |
| return checkConnectivity(network, AF_INET6, addrIpv6); |
| } |
| |
| private boolean checkConnectivity(@Nullable Network network, |
| int domain, @NonNull SocketAddress addr) { |
| final FileDescriptor socket; |
| try { |
| socket = Os.socket(domain, SOCK_DGRAM, IPPROTO_UDP); |
| } catch (ErrnoException e) { |
| return false; |
| } |
| try { |
| if (network != null) network.bindSocket(socket); |
| Os.connect(socket, addr); |
| } catch (IOException | ErrnoException e) { |
| return false; |
| } finally { |
| IoUtils.closeQuietly(socket); |
| } |
| return true; |
| } |
| |
| private static 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.getRecordCount(QDSECTION) == 0) { |
| throw new ParseException("No question found"); |
| } |
| // Expect only one question in question section. |
| mQueryType = mRecords[QDSECTION].get(0).nsType; |
| } |
| |
| public @NonNull List<InetAddress> getAddresses() { |
| final List<InetAddress> results = new ArrayList<InetAddress>(); |
| if (mHeader.getRecordCount(ANSECTION) == 0) return results; |
| |
| for (final DnsRecord ansSec : mRecords[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; |
| } |
| } |
| |
| } |