Merge changes from topic "Java async dns" am: 31ff0616d1

am: a8e16262f1

Change-Id: I305cf0ae791f9503519884bdf382863002357ac7

3 files changed, 552 insertions, 0 deletions

diff --git a/core/java/android/net/DnsPacket.java b/core/java/android/net/DnsPacket.java
new file mode 100644
index 000000000000..458fb340b196
--- /dev/null
+++ b/core/java/android/net/DnsPacket.java
@@ -0,0 +1,235 @@
+/*
+ * 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 android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.text.TextUtils;
+
+import com.android.internal.util.BitUtils;
+
+import java.nio.BufferUnderflowException;
+import java.nio.ByteBuffer;
+import java.text.DecimalFormat;
+import java.text.FieldPosition;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.StringJoiner;
+
+/**
+ * Defines basic data for DNS protocol based on RFC 1035.
+ * Subclasses create the specific format used in DNS packet.
+ *
+ * @hide
+ */
+public abstract class DnsPacket {
+    public class DnsHeader {
+        private static final String TAG = "DnsHeader";
+        public final int id;
+        public final int flags;
+        public final int rcode;
+        private final int[] mSectionCount;
+
+        /**
+         * Create a new DnsHeader from a positioned ByteBuffer.
+         *
+         * The ByteBuffer must be in network byte order (which is the default).
+         * Reads the passed ByteBuffer from its current position and decodes a DNS header.
+         * When this constructor returns, the reading position of the ByteBuffer has been
+         * advanced to the end of the DNS header record.
+         * This is meant to chain with other methods reading a DNS response in sequence.
+         *
+         */
+        DnsHeader(@NonNull ByteBuffer buf) throws BufferUnderflowException {
+            id = BitUtils.uint16(buf.getShort());
+            flags = BitUtils.uint16(buf.getShort());
+            rcode = flags & 0xF;
+            mSectionCount = new int[NUM_SECTIONS];
+            for (int i = 0; i < NUM_SECTIONS; ++i) {
+                mSectionCount[i] = BitUtils.uint16(buf.getShort());
+            }
+        }
+
+        /**
+         * Get section count by section type.
+         */
+        public int getSectionCount(int sectionType) {
+            return mSectionCount[sectionType];
+        }
+    }
+
+    public class DnsSection {
+        private static final int MAXNAMESIZE = 255;
+        private static final int MAXLABELSIZE = 63;
+        private static final int MAXLABELCOUNT = 128;
+        private static final int NAME_NORMAL = 0;
+        private static final int NAME_COMPRESSION = 0xC0;
+        private final DecimalFormat byteFormat = new DecimalFormat();
+        private final FieldPosition pos = new FieldPosition(0);
+
+        private static final String TAG = "DnsSection";
+
+        public final String dName;
+        public final int nsType;
+        public final int nsClass;
+        public final long ttl;
+        private final byte[] mRR;
+
+        /**
+         * Create a new DnsSection from a positioned ByteBuffer.
+         *
+         * The ByteBuffer must be in network byte order (which is the default).
+         * Reads the passed ByteBuffer from its current position and decodes a DNS section.
+         * When this constructor returns, the reading position of the ByteBuffer has been
+         * advanced to the end of the DNS header record.
+         * This is meant to chain with other methods reading a DNS response in sequence.
+         *
+         */
+        DnsSection(int sectionType, @NonNull ByteBuffer buf)
+                throws BufferUnderflowException, ParseException {
+            dName = parseName(buf, 0 /* Parse depth */);
+            if (dName.length() > MAXNAMESIZE) {
+                throw new ParseException("Parse name fail, name size is too long");
+            }
+            nsType = BitUtils.uint16(buf.getShort());
+            nsClass = BitUtils.uint16(buf.getShort());
+
+            if (sectionType != QDSECTION) {
+                ttl = BitUtils.uint32(buf.getInt());
+                final int length = BitUtils.uint16(buf.getShort());
+                mRR = new byte[length];
+                buf.get(mRR);
+            } else {
+                ttl = 0;
+                mRR = null;
+            }
+        }
+
+        /**
+         * Get a copy of rr.
+         */
+        @Nullable public byte[] getRR() {
+            return (mRR == null) ? null : mRR.clone();
+        }
+
+        /**
+         * Convert label from {@code byte[]} to {@code String}
+         *
+         * It follows the same converting rule as native layer.
+         * (See ns_name.c in libc)
+         *
+         */
+        private String labelToString(@NonNull byte[] label) {
+            final StringBuffer sb = new StringBuffer();
+            for (int i = 0; i < label.length; ++i) {
+                int b = BitUtils.uint8(label[i]);
+                // Control characters and non-ASCII characters.
+                if (b <= 0x20 || b >= 0x7f) {
+                    sb.append('\\');
+                    byteFormat.format(b, sb, pos);
+                } else if (b == '"' || b == '.' || b == ';' || b == '\\'
+                        || b == '(' || b == ')' || b == '@' || b == '$') {
+                    sb.append('\\');
+                    sb.append((char) b);
+                } else {
+                    sb.append((char) b);
+                }
+            }
+            return sb.toString();
+        }
+
+        private String parseName(@NonNull ByteBuffer buf, int depth) throws
+                BufferUnderflowException, ParseException {
+            if (depth > MAXLABELCOUNT) throw new ParseException("Parse name fails, too many labels");
+            final int len = BitUtils.uint8(buf.get());
+            final int mask = len & NAME_COMPRESSION;
+            if (0 == len) {
+                return "";
+            } else if (mask != NAME_NORMAL && mask != NAME_COMPRESSION) {
+                throw new ParseException("Parse name fail, bad label type");
+            } else if (mask == NAME_COMPRESSION) {
+                // Name compression based on RFC 1035 - 4.1.4 Message compression
+                final int offset = ((len & ~NAME_COMPRESSION) << 8) + BitUtils.uint8(buf.get());
+                final int oldPos = buf.position();
+                if (offset >= oldPos - 2) {
+                    throw new ParseException("Parse compression name fail, invalid compression");
+                }
+                buf.position(offset);
+                final String pointed = parseName(buf, depth + 1);
+                buf.position(oldPos);
+                return pointed;
+            } else {
+                final byte[] label = new byte[len];
+                buf.get(label);
+                final String head = labelToString(label);
+                if (head.length() > MAXLABELSIZE) {
+                    throw new ParseException("Parse name fail, invalid label length");
+                }
+                final String tail = parseName(buf, depth + 1);
+                return TextUtils.isEmpty(tail) ? head : head + "." + tail;
+            }
+        }
+    }
+
+    public static final int QDSECTION = 0;
+    public static final int ANSECTION = 1;
+    public static final int NSSECTION = 2;
+    public static final int ARSECTION = 3;
+    private static final int NUM_SECTIONS = ARSECTION + 1;
+
+    private static final String TAG = DnsPacket.class.getSimpleName();
+
+    protected final DnsHeader mHeader;
+    protected final List<DnsSection>[] mSections;
+
+    public static class ParseException extends Exception {
+        public ParseException(String msg) {
+            super(msg);
+        }
+
+        public ParseException(String msg, Throwable cause) {
+            super(msg, cause);
+        }
+    }
+
+    protected DnsPacket(@NonNull byte[] data) throws ParseException {
+        if (null == data) throw new ParseException("Parse header failed, null input data");
+        final ByteBuffer buffer;
+        try {
+            buffer = ByteBuffer.wrap(data);
+            mHeader = new DnsHeader(buffer);
+        } catch (BufferUnderflowException e) {
+            throw new ParseException("Parse Header fail, bad input data", e);
+        }
+
+        mSections = new ArrayList[NUM_SECTIONS];
+
+        for (int i = 0; i < NUM_SECTIONS; ++i) {
+            final int count = mHeader.getSectionCount(i);
+            if (count > 0) {
+                mSections[i] = new ArrayList(count);
+            }
+            for (int j = 0; j < count; ++j) {
+                try {
+                    mSections[i].add(new DnsSection(i, buffer));
+                } catch (BufferUnderflowException e) {
+                    throw new ParseException("Parse section fail", e);
+                }
+            }
+        }
+    }
+}
diff --git a/core/java/android/net/DnsResolver.java b/core/java/android/net/DnsResolver.java
new file mode 100644
index 000000000000..6d54264cd89f
--- /dev/null
+++ b/core/java/android/net/DnsResolver.java
@@ -0,0 +1,289 @@
+/*
+ * 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);
+            }
+        }
+    }
+}
diff --git a/core/java/android/net/NetworkUtils.java b/core/java/android/net/NetworkUtils.java
index c0aa4a6faf12..7f4d8cd1cfcb 100644
--- a/core/java/android/net/NetworkUtils.java
+++ b/core/java/android/net/NetworkUtils.java
@@ -34,6 +34,8 @@ import java.util.Collection;
 import java.util.Locale;
 import java.util.TreeSet;
 
+import android.system.ErrnoException;
+
 /**
  * Native methods for managing network interfaces.
  *
@@ -133,6 +135,32 @@ public class NetworkUtils {
     public native static boolean queryUserAccess(int uid, int netId);
 
     /**
+     * DNS resolver series jni method.
+     * Issue the query {@code msg} on the network designated by {@code netId}.
+     * {@code flags} is an additional config to control actual querying behavior.
+     * @return a file descriptor to watch for read events
+     */
+    public static native FileDescriptor resNetworkSend(
+            int netId, byte[] msg, int msglen, int flags) throws ErrnoException;
+
+    /**
+     * DNS resolver series jni method.
+     * Look up the {@code nsClass} {@code nsType} Resource Record (RR) associated
+     * with Domain Name {@code dname} on the network designated by {@code netId}.
+     * {@code flags} is an additional config to control actual querying behavior.
+     * @return a file descriptor to watch for read events
+     */
+    public static native FileDescriptor resNetworkQuery(
+            int netId, String dname, int nsClass, int nsType, int flags) throws ErrnoException;
+
+    /**
+     * DNS resolver series jni method.
+     * Read a result for the query associated with the {@code fd}.
+     * @return a byte array containing blob answer
+     */
+    public static native byte[] resNetworkResult(FileDescriptor fd) throws ErrnoException;
+
+    /**
      * Add an entry into the ARP cache.
      */
     public static void addArpEntry(Inet4Address ipv4Addr, MacAddress ethAddr, String ifname,