Unremove DnsResolver#query method used by external developers
This method was removed as part of addressing API council feedback in b/129261432
Add back previous DnsResolver#query which is already being used by developers.
Bug: 129395490
Test: atest DnsResolverTest
Change-Id: Ic956db204f3940d39d42e1b11dda39e57d356fad
diff --git a/core/java/android/net/DnsResolver.java b/core/java/android/net/DnsResolver.java
index f9e0af2..687b721 100644
--- a/core/java/android/net/DnsResolver.java
+++ b/core/java/android/net/DnsResolver.java
@@ -22,6 +22,10 @@
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;
@@ -30,12 +34,18 @@
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;
@@ -52,6 +62,7 @@
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 = 2;
@IntDef(prefix = { "CLASS_" }, value = {
CLASS_IN
@@ -188,9 +199,9 @@
* Send a raw DNS query.
* The answer will be provided asynchronously through the provided {@link AnswerCallback}.
*
- * @param network {@link Network} specifying which network for querying.
+ * @param network {@link Network} specifying which network to query on.
* {@code null} for query on default network.
- * @param query blob message
+ * @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
@@ -211,21 +222,23 @@
queryfd = resNetworkSend((network != null
? network.netId : NETID_UNSET), query, query.length, flags);
} catch (ErrnoException e) {
- callback.onQueryException(e);
+ executor.execute(() -> {
+ callback.onQueryException(e);
+ });
return;
}
- maybeAddCancellationSignal(cancellationSignal, queryfd, lock);
registerFDListener(executor, queryfd, callback, cancellationSignal, lock);
+ maybeAddCancellationSignal(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 for querying.
+ * @param network {@link Network} specifying which network to query on.
* {@code null} for query on default network.
- * @param domain domain name for querying
+ * @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
@@ -249,12 +262,145 @@
queryfd = resNetworkQuery((network != null
? network.netId : NETID_UNSET), domain, nsClass, nsType, flags);
} catch (ErrnoException e) {
- callback.onQueryException(e);
+ executor.execute(() -> {
+ callback.onQueryException(e);
+ });
return;
}
- maybeAddCancellationSignal(cancellationSignal, queryfd, lock);
registerFDListener(executor, queryfd, callback, cancellationSignal, lock);
+ maybeAddCancellationSignal(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 controll the sleep time.
+ // Avoiding gateways drop packets if queries are sent too close together
+ try {
+ Thread.sleep(SLEEP_TIME);
+ } 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);
+
+ 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,
@@ -271,7 +417,7 @@
}
byte[] answerbuf = null;
try {
- answerbuf = resNetworkResult(fd);
+ answerbuf = resNetworkResult(fd); // Closes fd, marks it invalid.
} catch (ErrnoException e) {
Log.e(TAG, "resNetworkResult:" + e.toString());
answerCallback.onQueryException(e);
@@ -291,19 +437,54 @@
});
}
+ private void cancelQuery(@NonNull FileDescriptor queryfd) {
+ if (!queryfd.valid()) return;
+ Looper.getMainLooper().getQueue().removeOnFileDescriptorEventListener(queryfd);
+ resNetworkCancel(queryfd); // Closes fd, marks it invalid.
+ }
+
private void maybeAddCancellationSignal(@Nullable CancellationSignal cancellationSignal,
@NonNull FileDescriptor queryfd, @NonNull Object lock) {
if (cancellationSignal == null) return;
cancellationSignal.setOnCancelListener(() -> {
synchronized (lock) {
- if (!queryfd.valid()) return;
- Looper.getMainLooper().getQueue()
- .removeOnFileDescriptorEventListener(queryfd);
- resNetworkCancel(queryfd);
+ 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;