diff --git a/packages/Nsd/service/Android.bp b/packages/Nsd/service/Android.bp
new file mode 100644
index 0000000..529f58d
--- /dev/null
+++ b/packages/Nsd/service/Android.bp
@@ -0,0 +1,31 @@
+//
+// Copyright (C) 2021 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 {
+    // See: http://go/android-license-faq
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+filegroup {
+    name: "services.connectivity-nsd-sources",
+    srcs: [
+        "src/**/*.java",
+    ],
+    path: "src",
+    visibility: [
+        "//frameworks/base/services/core",
+    ],
+}
diff --git a/packages/Nsd/service/src/com/android/server/INativeDaemonConnectorCallbacks.java b/packages/Nsd/service/src/com/android/server/INativeDaemonConnectorCallbacks.java
new file mode 100644
index 0000000..0cf9dcd
--- /dev/null
+++ b/packages/Nsd/service/src/com/android/server/INativeDaemonConnectorCallbacks.java
@@ -0,0 +1,25 @@
+
+/*
+ * Copyright (C) 2007 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 com.android.server;
+
+interface INativeDaemonConnectorCallbacks {
+
+    void onDaemonConnected();
+    boolean onCheckHoldWakeLock(int code);
+    boolean onEvent(int code, String raw, String[] cooked);
+}
diff --git a/packages/Nsd/service/src/com/android/server/NativeDaemonConnector.java b/packages/Nsd/service/src/com/android/server/NativeDaemonConnector.java
new file mode 100644
index 0000000..eac767f
--- /dev/null
+++ b/packages/Nsd/service/src/com/android/server/NativeDaemonConnector.java
@@ -0,0 +1,723 @@
+/*
+ * Copyright (C) 2007 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 com.android.server;
+
+import android.net.LocalSocket;
+import android.net.LocalSocketAddress;
+import android.os.Build;
+import android.os.Handler;
+import android.os.Looper;
+import android.os.Message;
+import android.os.PowerManager;
+import android.os.SystemClock;
+import android.os.SystemProperties;
+import android.util.LocalLog;
+import android.util.Slog;
+
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.internal.util.Preconditions;
+import com.android.server.power.ShutdownThread;
+import com.google.android.collect.Lists;
+
+import java.io.FileDescriptor;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.PrintWriter;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.LinkedList;
+import java.util.Objects;
+
+/**
+ * Generic connector class for interfacing with a native daemon which uses the
+ * {@code libsysutils} FrameworkListener protocol.
+ */
+final class NativeDaemonConnector implements Runnable, Handler.Callback, Watchdog.Monitor {
+    private final static boolean VDBG = false;
+
+    private final String TAG;
+
+    private String mSocket;
+    private OutputStream mOutputStream;
+    private LocalLog mLocalLog;
+
+    private volatile boolean mDebug = false;
+    private volatile Object mWarnIfHeld;
+
+    private final ResponseQueue mResponseQueue;
+
+    private final PowerManager.WakeLock mWakeLock;
+
+    private final Looper mLooper;
+
+    private INativeDaemonConnectorCallbacks mCallbacks;
+    private Handler mCallbackHandler;
+
+    private AtomicInteger mSequenceNumber;
+
+    private static final long DEFAULT_TIMEOUT = 1 * 60 * 1000; /* 1 minute */
+    private static final long WARN_EXECUTE_DELAY_MS = 500; /* .5 sec */
+
+    /** Lock held whenever communicating with native daemon. */
+    private final Object mDaemonLock = new Object();
+
+    private final int BUFFER_SIZE = 4096;
+
+    NativeDaemonConnector(INativeDaemonConnectorCallbacks callbacks, String socket,
+            int responseQueueSize, String logTag, int maxLogSize, PowerManager.WakeLock wl) {
+        this(callbacks, socket, responseQueueSize, logTag, maxLogSize, wl,
+                FgThread.get().getLooper());
+    }
+
+    NativeDaemonConnector(INativeDaemonConnectorCallbacks callbacks, String socket,
+            int responseQueueSize, String logTag, int maxLogSize, PowerManager.WakeLock wl,
+            Looper looper) {
+        mCallbacks = callbacks;
+        mSocket = socket;
+        mResponseQueue = new ResponseQueue(responseQueueSize);
+        mWakeLock = wl;
+        if (mWakeLock != null) {
+            mWakeLock.setReferenceCounted(true);
+        }
+        mLooper = looper;
+        mSequenceNumber = new AtomicInteger(0);
+        TAG = logTag != null ? logTag : "NativeDaemonConnector";
+        mLocalLog = new LocalLog(maxLogSize);
+    }
+
+    /**
+     * Enable Set debugging mode, which causes messages to also be written to both
+     * {@link Slog} in addition to internal log.
+     */
+    public void setDebug(boolean debug) {
+        mDebug = debug;
+    }
+
+    /**
+     * Like SystemClock.uptimeMillis, except truncated to an int so it will fit in a message arg.
+     * Inaccurate across 49.7 days of uptime, but only used for debugging.
+     */
+    private int uptimeMillisInt() {
+        return (int) SystemClock.uptimeMillis() & Integer.MAX_VALUE;
+    }
+
+    /**
+     * Yell loudly if someone tries making future {@link #execute(Command)}
+     * calls while holding a lock on the given object.
+     */
+    public void setWarnIfHeld(Object warnIfHeld) {
+        Preconditions.checkState(mWarnIfHeld == null);
+        mWarnIfHeld = Objects.requireNonNull(warnIfHeld);
+    }
+
+    @Override
+    public void run() {
+        mCallbackHandler = new Handler(mLooper, this);
+
+        while (true) {
+            if (isShuttingDown()) break;
+            try {
+                listenToSocket();
+            } catch (Exception e) {
+                loge("Error in NativeDaemonConnector: " + e);
+                if (isShuttingDown()) break;
+                SystemClock.sleep(5000);
+            }
+        }
+    }
+
+    private static boolean isShuttingDown() {
+        String shutdownAct = SystemProperties.get(
+            ShutdownThread.SHUTDOWN_ACTION_PROPERTY, "");
+        return shutdownAct != null && shutdownAct.length() > 0;
+    }
+
+    @Override
+    public boolean handleMessage(Message msg) {
+        final String event = (String) msg.obj;
+        final int start = uptimeMillisInt();
+        final int sent = msg.arg1;
+        try {
+            if (!mCallbacks.onEvent(msg.what, event, NativeDaemonEvent.unescapeArgs(event))) {
+                log(String.format("Unhandled event '%s'", event));
+            }
+        } catch (Exception e) {
+            loge("Error handling '" + event + "': " + e);
+        } finally {
+            if (mCallbacks.onCheckHoldWakeLock(msg.what) && mWakeLock != null) {
+                mWakeLock.release();
+            }
+            final int end = uptimeMillisInt();
+            if (start > sent && start - sent > WARN_EXECUTE_DELAY_MS) {
+                loge(String.format("NDC event {%s} processed too late: %dms", event, start - sent));
+            }
+            if (end > start && end - start > WARN_EXECUTE_DELAY_MS) {
+                loge(String.format("NDC event {%s} took too long: %dms", event, end - start));
+            }
+        }
+        return true;
+    }
+
+    private LocalSocketAddress determineSocketAddress() {
+        // If we're testing, set up a socket in a namespace that's accessible to test code.
+        // In order to ensure that unprivileged apps aren't able to impersonate native daemons on
+        // production devices, even if said native daemons ill-advisedly pick a socket name that
+        // starts with __test__, only allow this on debug builds.
+        if (mSocket.startsWith("__test__") && Build.IS_DEBUGGABLE) {
+            return new LocalSocketAddress(mSocket);
+        } else {
+            return new LocalSocketAddress(mSocket, LocalSocketAddress.Namespace.RESERVED);
+        }
+    }
+
+    private void listenToSocket() throws IOException {
+        LocalSocket socket = null;
+
+        try {
+            socket = new LocalSocket();
+            LocalSocketAddress address = determineSocketAddress();
+
+            socket.connect(address);
+
+            InputStream inputStream = socket.getInputStream();
+            synchronized (mDaemonLock) {
+                mOutputStream = socket.getOutputStream();
+            }
+
+            mCallbacks.onDaemonConnected();
+
+            FileDescriptor[] fdList = null;
+            byte[] buffer = new byte[BUFFER_SIZE];
+            int start = 0;
+
+            while (true) {
+                int count = inputStream.read(buffer, start, BUFFER_SIZE - start);
+                if (count < 0) {
+                    loge("got " + count + " reading with start = " + start);
+                    break;
+                }
+                fdList = socket.getAncillaryFileDescriptors();
+
+                // Add our starting point to the count and reset the start.
+                count += start;
+                start = 0;
+
+                for (int i = 0; i < count; i++) {
+                    if (buffer[i] == 0) {
+                        // Note - do not log this raw message since it may contain
+                        // sensitive data
+                        final String rawEvent = new String(
+                                buffer, start, i - start, StandardCharsets.UTF_8);
+
+                        boolean releaseWl = false;
+                        try {
+                            final NativeDaemonEvent event =
+                                    NativeDaemonEvent.parseRawEvent(rawEvent, fdList);
+
+                            log("RCV <- {" + event + "}");
+
+                            if (event.isClassUnsolicited()) {
+                                // TODO: migrate to sending NativeDaemonEvent instances
+                                if (mCallbacks.onCheckHoldWakeLock(event.getCode())
+                                        && mWakeLock != null) {
+                                    mWakeLock.acquire();
+                                    releaseWl = true;
+                                }
+                                Message msg = mCallbackHandler.obtainMessage(
+                                        event.getCode(), uptimeMillisInt(), 0, event.getRawEvent());
+                                if (mCallbackHandler.sendMessage(msg)) {
+                                    releaseWl = false;
+                                }
+                            } else {
+                                mResponseQueue.add(event.getCmdNumber(), event);
+                            }
+                        } catch (IllegalArgumentException e) {
+                            log("Problem parsing message " + e);
+                        } finally {
+                            if (releaseWl) {
+                                mWakeLock.release();
+                            }
+                        }
+
+                        start = i + 1;
+                    }
+                }
+
+                if (start == 0) {
+                    log("RCV incomplete");
+                }
+
+                // We should end at the amount we read. If not, compact then
+                // buffer and read again.
+                if (start != count) {
+                    final int remaining = BUFFER_SIZE - start;
+                    System.arraycopy(buffer, start, buffer, 0, remaining);
+                    start = remaining;
+                } else {
+                    start = 0;
+                }
+            }
+        } catch (IOException ex) {
+            loge("Communications error: " + ex);
+            throw ex;
+        } finally {
+            synchronized (mDaemonLock) {
+                if (mOutputStream != null) {
+                    try {
+                        loge("closing stream for " + mSocket);
+                        mOutputStream.close();
+                    } catch (IOException e) {
+                        loge("Failed closing output stream: " + e);
+                    }
+                    mOutputStream = null;
+                }
+            }
+
+            try {
+                if (socket != null) {
+                    socket.close();
+                }
+            } catch (IOException ex) {
+                loge("Failed closing socket: " + ex);
+            }
+        }
+    }
+
+    /**
+     * Wrapper around argument that indicates it's sensitive and shouldn't be
+     * logged.
+     */
+    public static class SensitiveArg {
+        private final Object mArg;
+
+        public SensitiveArg(Object arg) {
+            mArg = arg;
+        }
+
+        @Override
+        public String toString() {
+            return String.valueOf(mArg);
+        }
+    }
+
+    /**
+     * Make command for daemon, escaping arguments as needed.
+     */
+    @VisibleForTesting
+    static void makeCommand(StringBuilder rawBuilder, StringBuilder logBuilder, int sequenceNumber,
+            String cmd, Object... args) {
+        if (cmd.indexOf('\0') >= 0) {
+            throw new IllegalArgumentException("Unexpected command: " + cmd);
+        }
+        if (cmd.indexOf(' ') >= 0) {
+            throw new IllegalArgumentException("Arguments must be separate from command");
+        }
+
+        rawBuilder.append(sequenceNumber).append(' ').append(cmd);
+        logBuilder.append(sequenceNumber).append(' ').append(cmd);
+        for (Object arg : args) {
+            final String argString = String.valueOf(arg);
+            if (argString.indexOf('\0') >= 0) {
+                throw new IllegalArgumentException("Unexpected argument: " + arg);
+            }
+
+            rawBuilder.append(' ');
+            logBuilder.append(' ');
+
+            appendEscaped(rawBuilder, argString);
+            if (arg instanceof SensitiveArg) {
+                logBuilder.append("[scrubbed]");
+            } else {
+                appendEscaped(logBuilder, argString);
+            }
+        }
+
+        rawBuilder.append('\0');
+    }
+
+    /**
+     * Method that waits until all asychronous notifications sent by the native daemon have
+     * been processed. This method must not be called on the notification thread or an
+     * exception will be thrown.
+     */
+    public void waitForCallbacks() {
+        if (Thread.currentThread() == mLooper.getThread()) {
+            throw new IllegalStateException("Must not call this method on callback thread");
+        }
+
+        final CountDownLatch latch = new CountDownLatch(1);
+        mCallbackHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                latch.countDown();
+            }
+        });
+        try {
+            latch.await();
+        } catch (InterruptedException e) {
+            Slog.wtf(TAG, "Interrupted while waiting for unsolicited response handling", e);
+        }
+    }
+
+    /**
+     * Issue the given command to the native daemon and return a single expected
+     * response.
+     *
+     * @throws NativeDaemonConnectorException when problem communicating with
+     *             native daemon, or if the response matches
+     *             {@link NativeDaemonEvent#isClassClientError()} or
+     *             {@link NativeDaemonEvent#isClassServerError()}.
+     */
+    public NativeDaemonEvent execute(Command cmd) throws NativeDaemonConnectorException {
+        return execute(cmd.mCmd, cmd.mArguments.toArray());
+    }
+
+    /**
+     * Issue the given command to the native daemon and return a single expected
+     * response. Any arguments must be separated from base command so they can
+     * be properly escaped.
+     *
+     * @throws NativeDaemonConnectorException when problem communicating with
+     *             native daemon, or if the response matches
+     *             {@link NativeDaemonEvent#isClassClientError()} or
+     *             {@link NativeDaemonEvent#isClassServerError()}.
+     */
+    public NativeDaemonEvent execute(String cmd, Object... args)
+            throws NativeDaemonConnectorException {
+        return execute(DEFAULT_TIMEOUT, cmd, args);
+    }
+
+    public NativeDaemonEvent execute(long timeoutMs, String cmd, Object... args)
+            throws NativeDaemonConnectorException {
+        final NativeDaemonEvent[] events = executeForList(timeoutMs, cmd, args);
+        if (events.length != 1) {
+            throw new NativeDaemonConnectorException(
+                    "Expected exactly one response, but received " + events.length);
+        }
+        return events[0];
+    }
+
+    /**
+     * Issue the given command to the native daemon and return any
+     * {@link NativeDaemonEvent#isClassContinue()} responses, including the
+     * final terminal response.
+     *
+     * @throws NativeDaemonConnectorException when problem communicating with
+     *             native daemon, or if the response matches
+     *             {@link NativeDaemonEvent#isClassClientError()} or
+     *             {@link NativeDaemonEvent#isClassServerError()}.
+     */
+    public NativeDaemonEvent[] executeForList(Command cmd) throws NativeDaemonConnectorException {
+        return executeForList(cmd.mCmd, cmd.mArguments.toArray());
+    }
+
+    /**
+     * Issue the given command to the native daemon and return any
+     * {@link NativeDaemonEvent#isClassContinue()} responses, including the
+     * final terminal response. Any arguments must be separated from base
+     * command so they can be properly escaped.
+     *
+     * @throws NativeDaemonConnectorException when problem communicating with
+     *             native daemon, or if the response matches
+     *             {@link NativeDaemonEvent#isClassClientError()} or
+     *             {@link NativeDaemonEvent#isClassServerError()}.
+     */
+    public NativeDaemonEvent[] executeForList(String cmd, Object... args)
+            throws NativeDaemonConnectorException {
+        return executeForList(DEFAULT_TIMEOUT, cmd, args);
+    }
+
+    /**
+     * Issue the given command to the native daemon and return any {@linke
+     * NativeDaemonEvent@isClassContinue()} responses, including the final
+     * terminal response. Note that the timeout does not count time in deep
+     * sleep. Any arguments must be separated from base command so they can be
+     * properly escaped.
+     *
+     * @throws NativeDaemonConnectorException when problem communicating with
+     *             native daemon, or if the response matches
+     *             {@link NativeDaemonEvent#isClassClientError()} or
+     *             {@link NativeDaemonEvent#isClassServerError()}.
+     */
+    public NativeDaemonEvent[] executeForList(long timeoutMs, String cmd, Object... args)
+            throws NativeDaemonConnectorException {
+        if (mWarnIfHeld != null && Thread.holdsLock(mWarnIfHeld)) {
+            Slog.wtf(TAG, "Calling thread " + Thread.currentThread().getName() + " is holding 0x"
+                    + Integer.toHexString(System.identityHashCode(mWarnIfHeld)), new Throwable());
+        }
+
+        final long startTime = SystemClock.elapsedRealtime();
+
+        final ArrayList<NativeDaemonEvent> events = Lists.newArrayList();
+
+        final StringBuilder rawBuilder = new StringBuilder();
+        final StringBuilder logBuilder = new StringBuilder();
+        final int sequenceNumber = mSequenceNumber.incrementAndGet();
+
+        makeCommand(rawBuilder, logBuilder, sequenceNumber, cmd, args);
+
+        final String rawCmd = rawBuilder.toString();
+        final String logCmd = logBuilder.toString();
+
+        log("SND -> {" + logCmd + "}");
+
+        synchronized (mDaemonLock) {
+            if (mOutputStream == null) {
+                throw new NativeDaemonConnectorException("missing output stream");
+            } else {
+                try {
+                    mOutputStream.write(rawCmd.getBytes(StandardCharsets.UTF_8));
+                } catch (IOException e) {
+                    throw new NativeDaemonConnectorException("problem sending command", e);
+                }
+            }
+        }
+
+        NativeDaemonEvent event = null;
+        do {
+            event = mResponseQueue.remove(sequenceNumber, timeoutMs, logCmd);
+            if (event == null) {
+                loge("timed-out waiting for response to " + logCmd);
+                throw new NativeDaemonTimeoutException(logCmd, event);
+            }
+            if (VDBG) log("RMV <- {" + event + "}");
+            events.add(event);
+        } while (event.isClassContinue());
+
+        final long endTime = SystemClock.elapsedRealtime();
+        if (endTime - startTime > WARN_EXECUTE_DELAY_MS) {
+            loge("NDC Command {" + logCmd + "} took too long (" + (endTime - startTime) + "ms)");
+        }
+
+        if (event.isClassClientError()) {
+            throw new NativeDaemonArgumentException(logCmd, event);
+        }
+        if (event.isClassServerError()) {
+            throw new NativeDaemonFailureException(logCmd, event);
+        }
+
+        return events.toArray(new NativeDaemonEvent[events.size()]);
+    }
+
+    /**
+     * Append the given argument to {@link StringBuilder}, escaping as needed,
+     * and surrounding with quotes when it contains spaces.
+     */
+    @VisibleForTesting
+    static void appendEscaped(StringBuilder builder, String arg) {
+        final boolean hasSpaces = arg.indexOf(' ') >= 0;
+        if (hasSpaces) {
+            builder.append('"');
+        }
+
+        final int length = arg.length();
+        for (int i = 0; i < length; i++) {
+            final char c = arg.charAt(i);
+
+            if (c == '"') {
+                builder.append("\\\"");
+            } else if (c == '\\') {
+                builder.append("\\\\");
+            } else {
+                builder.append(c);
+            }
+        }
+
+        if (hasSpaces) {
+            builder.append('"');
+        }
+    }
+
+    private static class NativeDaemonArgumentException extends NativeDaemonConnectorException {
+        public NativeDaemonArgumentException(String command, NativeDaemonEvent event) {
+            super(command, event);
+        }
+
+        @Override
+        public IllegalArgumentException rethrowAsParcelableException() {
+            throw new IllegalArgumentException(getMessage(), this);
+        }
+    }
+
+    private static class NativeDaemonFailureException extends NativeDaemonConnectorException {
+        public NativeDaemonFailureException(String command, NativeDaemonEvent event) {
+            super(command, event);
+        }
+    }
+
+    /**
+     * Command builder that handles argument list building. Any arguments must
+     * be separated from base command so they can be properly escaped.
+     */
+    public static class Command {
+        private String mCmd;
+        private ArrayList<Object> mArguments = Lists.newArrayList();
+
+        public Command(String cmd, Object... args) {
+            mCmd = cmd;
+            for (Object arg : args) {
+                appendArg(arg);
+            }
+        }
+
+        public Command appendArg(Object arg) {
+            mArguments.add(arg);
+            return this;
+        }
+    }
+
+    /** {@inheritDoc} */
+    public void monitor() {
+        synchronized (mDaemonLock) { }
+    }
+
+    public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
+        mLocalLog.dump(fd, pw, args);
+        pw.println();
+        mResponseQueue.dump(fd, pw, args);
+    }
+
+    private void log(String logstring) {
+        if (mDebug) Slog.d(TAG, logstring);
+        mLocalLog.log(logstring);
+    }
+
+    private void loge(String logstring) {
+        Slog.e(TAG, logstring);
+        mLocalLog.log(logstring);
+    }
+
+    private static class ResponseQueue {
+
+        private static class PendingCmd {
+            public final int cmdNum;
+            public final String logCmd;
+
+            public BlockingQueue<NativeDaemonEvent> responses =
+                    new ArrayBlockingQueue<NativeDaemonEvent>(10);
+
+            // The availableResponseCount member is used to track when we can remove this
+            // instance from the ResponseQueue.
+            // This is used under the protection of a sync of the mPendingCmds object.
+            // A positive value means we've had more writers retreive this object while
+            // a negative value means we've had more readers.  When we've had an equal number
+            // (it goes to zero) we can remove this object from the mPendingCmds list.
+            // Note that we may have more responses for this command (and more readers
+            // coming), but that would result in a new PendingCmd instance being created
+            // and added with the same cmdNum.
+            // Also note that when this goes to zero it just means a parity of readers and
+            // writers have retrieved this object - not that they are done using it.  The
+            // responses queue may well have more responses yet to be read or may get more
+            // responses added to it.  But all those readers/writers have retreived and
+            // hold references to this instance already so it can be removed from
+            // mPendingCmds queue.
+            public int availableResponseCount;
+
+            public PendingCmd(int cmdNum, String logCmd) {
+                this.cmdNum = cmdNum;
+                this.logCmd = logCmd;
+            }
+        }
+
+        private final LinkedList<PendingCmd> mPendingCmds;
+        private int mMaxCount;
+
+        ResponseQueue(int maxCount) {
+            mPendingCmds = new LinkedList<PendingCmd>();
+            mMaxCount = maxCount;
+        }
+
+        public void add(int cmdNum, NativeDaemonEvent response) {
+            PendingCmd found = null;
+            synchronized (mPendingCmds) {
+                for (PendingCmd pendingCmd : mPendingCmds) {
+                    if (pendingCmd.cmdNum == cmdNum) {
+                        found = pendingCmd;
+                        break;
+                    }
+                }
+                if (found == null) {
+                    // didn't find it - make sure our queue isn't too big before adding
+                    while (mPendingCmds.size() >= mMaxCount) {
+                        Slog.e("NativeDaemonConnector.ResponseQueue",
+                                "more buffered than allowed: " + mPendingCmds.size() +
+                                " >= " + mMaxCount);
+                        // let any waiter timeout waiting for this
+                        PendingCmd pendingCmd = mPendingCmds.remove();
+                        Slog.e("NativeDaemonConnector.ResponseQueue",
+                                "Removing request: " + pendingCmd.logCmd + " (" +
+                                pendingCmd.cmdNum + ")");
+                    }
+                    found = new PendingCmd(cmdNum, null);
+                    mPendingCmds.add(found);
+                }
+                found.availableResponseCount++;
+                // if a matching remove call has already retrieved this we can remove this
+                // instance from our list
+                if (found.availableResponseCount == 0) mPendingCmds.remove(found);
+            }
+            try {
+                found.responses.put(response);
+            } catch (InterruptedException e) { }
+        }
+
+        // note that the timeout does not count time in deep sleep.  If you don't want
+        // the device to sleep, hold a wakelock
+        public NativeDaemonEvent remove(int cmdNum, long timeoutMs, String logCmd) {
+            PendingCmd found = null;
+            synchronized (mPendingCmds) {
+                for (PendingCmd pendingCmd : mPendingCmds) {
+                    if (pendingCmd.cmdNum == cmdNum) {
+                        found = pendingCmd;
+                        break;
+                    }
+                }
+                if (found == null) {
+                    found = new PendingCmd(cmdNum, logCmd);
+                    mPendingCmds.add(found);
+                }
+                found.availableResponseCount--;
+                // if a matching add call has already retrieved this we can remove this
+                // instance from our list
+                if (found.availableResponseCount == 0) mPendingCmds.remove(found);
+            }
+            NativeDaemonEvent result = null;
+            try {
+                result = found.responses.poll(timeoutMs, TimeUnit.MILLISECONDS);
+            } catch (InterruptedException e) {}
+            if (result == null) {
+                Slog.e("NativeDaemonConnector.ResponseQueue", "Timeout waiting for response");
+            }
+            return result;
+        }
+
+        public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
+            pw.println("Pending requests:");
+            synchronized (mPendingCmds) {
+                for (PendingCmd pendingCmd : mPendingCmds) {
+                    pw.println("  Cmd " + pendingCmd.cmdNum + " - " + pendingCmd.logCmd);
+                }
+            }
+        }
+    }
+}
diff --git a/packages/Nsd/service/src/com/android/server/NativeDaemonConnectorException.java b/packages/Nsd/service/src/com/android/server/NativeDaemonConnectorException.java
new file mode 100644
index 0000000..4d8881c
--- /dev/null
+++ b/packages/Nsd/service/src/com/android/server/NativeDaemonConnectorException.java
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2006 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 com.android.server;
+
+import android.os.Parcel;
+
+/**
+ * An exception that indicates there was an error with a
+ * {@link NativeDaemonConnector} operation.
+ */
+public class NativeDaemonConnectorException extends Exception {
+    private String mCmd;
+    private NativeDaemonEvent mEvent;
+
+    public NativeDaemonConnectorException(String detailMessage) {
+        super(detailMessage);
+    }
+
+    public NativeDaemonConnectorException(String detailMessage, Throwable throwable) {
+        super(detailMessage, throwable);
+    }
+
+    public NativeDaemonConnectorException(String cmd, NativeDaemonEvent event) {
+        super("command '" + cmd + "' failed with '" + event + "'");
+        mCmd = cmd;
+        mEvent = event;
+    }
+
+    public int getCode() {
+        return mEvent != null ? mEvent.getCode() : -1;
+    }
+
+    public String getCmd() {
+        return mCmd;
+    }
+
+    /**
+     * Rethrow as a {@link RuntimeException} subclass that is handled by
+     * {@link Parcel#writeException(Exception)}.
+     */
+    public IllegalArgumentException rethrowAsParcelableException() {
+        throw new IllegalStateException(getMessage(), this);
+    }
+}
diff --git a/packages/Nsd/service/src/com/android/server/NativeDaemonEvent.java b/packages/Nsd/service/src/com/android/server/NativeDaemonEvent.java
new file mode 100644
index 0000000..e6feda3
--- /dev/null
+++ b/packages/Nsd/service/src/com/android/server/NativeDaemonEvent.java
@@ -0,0 +1,268 @@
+/*
+ * Copyright (C) 2011 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 com.android.server;
+
+import android.util.Slog;
+import com.google.android.collect.Lists;
+
+import java.io.FileDescriptor;
+import java.util.ArrayList;
+
+/**
+ * Parsed event from native side of {@link NativeDaemonConnector}.
+ */
+public class NativeDaemonEvent {
+
+    // TODO: keep class ranges in sync with ResponseCode.h
+    // TODO: swap client and server error ranges to roughly mirror HTTP spec
+
+    private final int mCmdNumber;
+    private final int mCode;
+    private final String mMessage;
+    private final String mRawEvent;
+    private final String mLogMessage;
+    private String[] mParsed;
+    private FileDescriptor[] mFdList;
+
+    private NativeDaemonEvent(int cmdNumber, int code, String message,
+                              String rawEvent, String logMessage, FileDescriptor[] fdList) {
+        mCmdNumber = cmdNumber;
+        mCode = code;
+        mMessage = message;
+        mRawEvent = rawEvent;
+        mLogMessage = logMessage;
+        mParsed = null;
+        mFdList = fdList;
+    }
+
+    static public final String SENSITIVE_MARKER = "{{sensitive}}";
+
+    public int getCmdNumber() {
+        return mCmdNumber;
+    }
+
+    public int getCode() {
+        return mCode;
+    }
+
+    public String getMessage() {
+        return mMessage;
+    }
+
+    public FileDescriptor[] getFileDescriptors() {
+        return mFdList;
+    }
+
+    @Deprecated
+    public String getRawEvent() {
+        return mRawEvent;
+    }
+
+    @Override
+    public String toString() {
+        return mLogMessage;
+    }
+
+    /**
+     * Test if event represents a partial response which is continued in
+     * additional subsequent events.
+     */
+    public boolean isClassContinue() {
+        return mCode >= 100 && mCode < 200;
+    }
+
+    /**
+     * Test if event represents a command success.
+     */
+    public boolean isClassOk() {
+        return mCode >= 200 && mCode < 300;
+    }
+
+    /**
+     * Test if event represents a remote native daemon error.
+     */
+    public boolean isClassServerError() {
+        return mCode >= 400 && mCode < 500;
+    }
+
+    /**
+     * Test if event represents a command syntax or argument error.
+     */
+    public boolean isClassClientError() {
+        return mCode >= 500 && mCode < 600;
+    }
+
+    /**
+     * Test if event represents an unsolicited event from native daemon.
+     */
+    public boolean isClassUnsolicited() {
+        return isClassUnsolicited(mCode);
+    }
+
+    private static boolean isClassUnsolicited(int code) {
+        return code >= 600 && code < 700;
+    }
+
+    /**
+     * Verify this event matches the given code.
+     *
+     * @throws IllegalStateException if {@link #getCode()} doesn't match.
+     */
+    public void checkCode(int code) {
+        if (mCode != code) {
+            throw new IllegalStateException("Expected " + code + " but was: " + this);
+        }
+    }
+
+    /**
+     * Parse the given raw event into {@link NativeDaemonEvent} instance.
+     *
+     * @throws IllegalArgumentException when line doesn't match format expected
+     *             from native side.
+     */
+    public static NativeDaemonEvent parseRawEvent(String rawEvent, FileDescriptor[] fdList) {
+        final String[] parsed = rawEvent.split(" ");
+        if (parsed.length < 2) {
+            throw new IllegalArgumentException("Insufficient arguments");
+        }
+
+        int skiplength = 0;
+
+        final int code;
+        try {
+            code = Integer.parseInt(parsed[0]);
+            skiplength = parsed[0].length() + 1;
+        } catch (NumberFormatException e) {
+            throw new IllegalArgumentException("problem parsing code", e);
+        }
+
+        int cmdNumber = -1;
+        if (isClassUnsolicited(code) == false) {
+            if (parsed.length < 3) {
+                throw new IllegalArgumentException("Insufficient arguemnts");
+            }
+            try {
+                cmdNumber = Integer.parseInt(parsed[1]);
+                skiplength += parsed[1].length() + 1;
+            } catch (NumberFormatException e) {
+                throw new IllegalArgumentException("problem parsing cmdNumber", e);
+            }
+        }
+
+        String logMessage = rawEvent;
+        if (parsed.length > 2 && parsed[2].equals(SENSITIVE_MARKER)) {
+            skiplength += parsed[2].length() + 1;
+            logMessage = parsed[0] + " " + parsed[1] + " {}";
+        }
+
+        final String message = rawEvent.substring(skiplength);
+
+        return new NativeDaemonEvent(cmdNumber, code, message, rawEvent, logMessage, fdList);
+    }
+
+    /**
+     * Filter the given {@link NativeDaemonEvent} list, returning
+     * {@link #getMessage()} for any events matching the requested code.
+     */
+    public static String[] filterMessageList(NativeDaemonEvent[] events, int matchCode) {
+        final ArrayList<String> result = Lists.newArrayList();
+        for (NativeDaemonEvent event : events) {
+            if (event.getCode() == matchCode) {
+                result.add(event.getMessage());
+            }
+        }
+        return result.toArray(new String[result.size()]);
+    }
+
+    /**
+     * Find the Nth field of the event.
+     *
+     * This ignores and code or cmdNum, the first return value is given for N=0.
+     * Also understands "\"quoted\" multiword responses" and tries them as a single field
+     */
+    public String getField(int n) {
+        if (mParsed == null) {
+            mParsed = unescapeArgs(mRawEvent);
+        }
+        n += 2; // skip code and command#
+        if (n > mParsed.length) return null;
+            return mParsed[n];
+        }
+
+    public static String[] unescapeArgs(String rawEvent) {
+        final boolean DEBUG_ROUTINE = false;
+        final String LOGTAG = "unescapeArgs";
+        final ArrayList<String> parsed = new ArrayList<String>();
+        final int length = rawEvent.length();
+        int current = 0;
+        int wordEnd = -1;
+        boolean quoted = false;
+
+        if (DEBUG_ROUTINE) Slog.e(LOGTAG, "parsing '" + rawEvent + "'");
+        if (rawEvent.charAt(current) == '\"') {
+            quoted = true;
+            current++;
+        }
+        while (current < length) {
+            // find the end of the word
+            char terminator = quoted ? '\"' : ' ';
+            wordEnd = current;
+            while (wordEnd < length && rawEvent.charAt(wordEnd) != terminator) {
+                if (rawEvent.charAt(wordEnd) == '\\') {
+                    // skip the escaped char
+                    ++wordEnd;
+                }
+                ++wordEnd;
+            }
+            if (wordEnd > length) wordEnd = length;
+            String word = rawEvent.substring(current, wordEnd);
+            current += word.length();
+            if (!quoted) {
+                word = word.trim();
+            } else {
+                current++;  // skip the trailing quote
+            }
+            // unescape stuff within the word
+            word = word.replace("\\\\", "\\");
+            word = word.replace("\\\"", "\"");
+
+            if (DEBUG_ROUTINE) Slog.e(LOGTAG, "found '" + word + "'");
+            parsed.add(word);
+
+            // find the beginning of the next word - either of these options
+            int nextSpace = rawEvent.indexOf(' ', current);
+            int nextQuote = rawEvent.indexOf(" \"", current);
+            if (DEBUG_ROUTINE) {
+                Slog.e(LOGTAG, "nextSpace=" + nextSpace + ", nextQuote=" + nextQuote);
+            }
+            if (nextQuote > -1 && nextQuote <= nextSpace) {
+                quoted = true;
+                current = nextQuote + 2;
+            } else {
+                quoted = false;
+                if (nextSpace > -1) {
+                    current = nextSpace + 1;
+                }
+            } // else we just start the next word after the current and read til the end
+            if (DEBUG_ROUTINE) {
+                Slog.e(LOGTAG, "next loop - current=" + current +
+                        ", length=" + length + ", quoted=" + quoted);
+            }
+        }
+        return parsed.toArray(new String[parsed.size()]);
+    }
+}
diff --git a/packages/Nsd/service/src/com/android/server/NativeDaemonTimeoutException.java b/packages/Nsd/service/src/com/android/server/NativeDaemonTimeoutException.java
new file mode 100644
index 0000000..658f7d6
--- /dev/null
+++ b/packages/Nsd/service/src/com/android/server/NativeDaemonTimeoutException.java
@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2015 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 com.android.server;
+
+/**
+ * An exception that indicates there was a timeout with a
+ * {@link NativeDaemonConnector} operation.
+ */
+public class NativeDaemonTimeoutException extends NativeDaemonConnectorException {
+    public NativeDaemonTimeoutException(String command, NativeDaemonEvent event) {
+        super(command, event);
+    }
+}
+
diff --git a/packages/Nsd/service/src/com/android/server/NsdService.java b/packages/Nsd/service/src/com/android/server/NsdService.java
new file mode 100644
index 0000000..3e02084
--- /dev/null
+++ b/packages/Nsd/service/src/com/android/server/NsdService.java
@@ -0,0 +1,1103 @@
+/*
+ * Copyright (C) 2021 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 com.android.server;
+
+import android.content.ContentResolver;
+import android.content.Context;
+import android.content.Intent;
+import android.database.ContentObserver;
+import android.net.Uri;
+import android.net.nsd.INsdManager;
+import android.net.nsd.INsdManagerCallback;
+import android.net.nsd.INsdServiceConnector;
+import android.net.nsd.NsdManager;
+import android.net.nsd.NsdServiceInfo;
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.os.IBinder;
+import android.os.Message;
+import android.os.RemoteException;
+import android.os.UserHandle;
+import android.provider.Settings;
+import android.util.Base64;
+import android.util.Log;
+import android.util.Pair;
+import android.util.Slog;
+import android.util.SparseArray;
+import android.util.SparseIntArray;
+
+import com.android.internal.annotations.VisibleForTesting;
+import com.android.internal.util.DumpUtils;
+import com.android.internal.util.State;
+import com.android.internal.util.StateMachine;
+import com.android.net.module.util.DnsSdTxtRecord;
+
+import java.io.FileDescriptor;
+import java.io.PrintWriter;
+import java.net.InetAddress;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.concurrent.CountDownLatch;
+
+/**
+ * Network Service Discovery Service handles remote service discovery operation requests by
+ * implementing the INsdManager interface.
+ *
+ * @hide
+ */
+public class NsdService extends INsdManager.Stub {
+    private static final String TAG = "NsdService";
+    private static final String MDNS_TAG = "mDnsConnector";
+
+    private static final boolean DBG = true;
+    private static final long CLEANUP_DELAY_MS = 10000;
+
+    private final Context mContext;
+    private final NsdSettings mNsdSettings;
+    private final NsdStateMachine mNsdStateMachine;
+    private final DaemonConnection mDaemon;
+    private final NativeCallbackReceiver mDaemonCallback;
+
+    /**
+     * Clients receiving asynchronous messages
+     */
+    private final HashMap<NsdServiceConnector, ClientInfo> mClients = new HashMap<>();
+
+    /* A map from unique id to client info */
+    private final SparseArray<ClientInfo> mIdToClientInfoMap= new SparseArray<>();
+
+    private final long mCleanupDelayMs;
+
+    private static final int INVALID_ID = 0;
+    private int mUniqueId = 1;
+    // The count of the connected legacy clients.
+    private int mLegacyClientCount = 0;
+
+    private class NsdStateMachine extends StateMachine {
+
+        private final DefaultState mDefaultState = new DefaultState();
+        private final DisabledState mDisabledState = new DisabledState();
+        private final EnabledState mEnabledState = new EnabledState();
+
+        @Override
+        protected String getWhatToString(int what) {
+            return NsdManager.nameOf(what);
+        }
+
+        private void maybeStartDaemon() {
+            mDaemon.maybeStart();
+            maybeScheduleStop();
+        }
+
+        private boolean isAnyRequestActive() {
+            return mIdToClientInfoMap.size() != 0;
+        }
+
+        private void scheduleStop() {
+            sendMessageDelayed(NsdManager.DAEMON_CLEANUP, mCleanupDelayMs);
+        }
+        private void maybeScheduleStop() {
+            // The native daemon should stay alive and can't be cleanup
+            // if any legacy client connected.
+            if (!isAnyRequestActive() && mLegacyClientCount == 0) {
+                scheduleStop();
+            }
+        }
+
+        private void cancelStop() {
+            this.removeMessages(NsdManager.DAEMON_CLEANUP);
+        }
+
+        /**
+         * Observes the NSD on/off setting, and takes action when changed.
+         */
+        private void registerForNsdSetting() {
+            final ContentObserver contentObserver = new ContentObserver(this.getHandler()) {
+                @Override
+                public void onChange(boolean selfChange) {
+                    notifyEnabled(isNsdEnabled());
+                }
+            };
+
+            final Uri uri = Settings.Global.getUriFor(Settings.Global.NSD_ON);
+            mNsdSettings.registerContentObserver(uri, contentObserver);
+        }
+
+        NsdStateMachine(String name, Handler handler) {
+            super(name, handler);
+            addState(mDefaultState);
+                addState(mDisabledState, mDefaultState);
+                addState(mEnabledState, mDefaultState);
+            State initialState = isNsdEnabled() ? mEnabledState : mDisabledState;
+            setInitialState(initialState);
+            setLogRecSize(25);
+            registerForNsdSetting();
+        }
+
+        class DefaultState extends State {
+            @Override
+            public boolean processMessage(Message msg) {
+                final ClientInfo cInfo;
+                final int clientId = msg.arg2;
+                switch (msg.what) {
+                    case NsdManager.REGISTER_CLIENT:
+                        final Pair<NsdServiceConnector, INsdManagerCallback> arg =
+                                (Pair<NsdServiceConnector, INsdManagerCallback>) msg.obj;
+                        final INsdManagerCallback cb = arg.second;
+                        try {
+                            cb.asBinder().linkToDeath(arg.first, 0);
+                            cInfo = new ClientInfo(cb);
+                            mClients.put(arg.first, cInfo);
+                        } catch (RemoteException e) {
+                            Log.w(TAG, "Client " + clientId + " has already died");
+                        }
+                        break;
+                    case NsdManager.UNREGISTER_CLIENT:
+                        final NsdServiceConnector connector = (NsdServiceConnector) msg.obj;
+                        cInfo = mClients.remove(connector);
+                        if (cInfo != null) {
+                            cInfo.expungeAllRequests();
+                            if (cInfo.isLegacy()) {
+                                mLegacyClientCount -= 1;
+                            }
+                        }
+                        maybeScheduleStop();
+                        break;
+                    case NsdManager.DISCOVER_SERVICES:
+                        cInfo = getClientInfoForReply(msg);
+                        if (cInfo != null) {
+                            cInfo.onDiscoverServicesFailed(
+                                    clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                        }
+                       break;
+                    case NsdManager.STOP_DISCOVERY:
+                        cInfo = getClientInfoForReply(msg);
+                        if (cInfo != null) {
+                            cInfo.onStopDiscoveryFailed(
+                                    clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                        }
+                        break;
+                    case NsdManager.REGISTER_SERVICE:
+                        cInfo = getClientInfoForReply(msg);
+                        if (cInfo != null) {
+                            cInfo.onRegisterServiceFailed(
+                                    clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                        }
+                        break;
+                    case NsdManager.UNREGISTER_SERVICE:
+                        cInfo = getClientInfoForReply(msg);
+                        if (cInfo != null) {
+                            cInfo.onUnregisterServiceFailed(
+                                    clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                        }
+                        break;
+                    case NsdManager.RESOLVE_SERVICE:
+                        cInfo = getClientInfoForReply(msg);
+                        if (cInfo != null) {
+                            cInfo.onResolveServiceFailed(
+                                    clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                        }
+                        break;
+                    case NsdManager.DAEMON_CLEANUP:
+                        mDaemon.maybeStop();
+                        break;
+                    // This event should be only sent by the legacy (target SDK < S) clients.
+                    // Mark the sending client as legacy.
+                    case NsdManager.DAEMON_STARTUP:
+                        cInfo = getClientInfoForReply(msg);
+                        if (cInfo != null) {
+                            cancelStop();
+                            cInfo.setLegacy();
+                            mLegacyClientCount += 1;
+                            maybeStartDaemon();
+                        }
+                        break;
+                    case NsdManager.NATIVE_DAEMON_EVENT:
+                    default:
+                        Slog.e(TAG, "Unhandled " + msg);
+                        return NOT_HANDLED;
+                }
+                return HANDLED;
+            }
+
+            private ClientInfo getClientInfoForReply(Message msg) {
+                final ListenerArgs args = (ListenerArgs) msg.obj;
+                return mClients.get(args.connector);
+            }
+        }
+
+        class DisabledState extends State {
+            @Override
+            public void enter() {
+                sendNsdStateChangeBroadcast(false);
+            }
+
+            @Override
+            public boolean processMessage(Message msg) {
+                switch (msg.what) {
+                    case NsdManager.ENABLE:
+                        transitionTo(mEnabledState);
+                        break;
+                    default:
+                        return NOT_HANDLED;
+                }
+                return HANDLED;
+            }
+        }
+
+        class EnabledState extends State {
+            @Override
+            public void enter() {
+                sendNsdStateChangeBroadcast(true);
+            }
+
+            @Override
+            public void exit() {
+                // TODO: it is incorrect to stop the daemon without expunging all requests
+                // and sending error callbacks to clients.
+                scheduleStop();
+            }
+
+            private boolean requestLimitReached(ClientInfo clientInfo) {
+                if (clientInfo.mClientIds.size() >= ClientInfo.MAX_LIMIT) {
+                    if (DBG) Slog.d(TAG, "Exceeded max outstanding requests " + clientInfo);
+                    return true;
+                }
+                return false;
+            }
+
+            private void storeRequestMap(int clientId, int globalId, ClientInfo clientInfo, int what) {
+                clientInfo.mClientIds.put(clientId, globalId);
+                clientInfo.mClientRequests.put(clientId, what);
+                mIdToClientInfoMap.put(globalId, clientInfo);
+                // Remove the cleanup event because here comes a new request.
+                cancelStop();
+            }
+
+            private void removeRequestMap(int clientId, int globalId, ClientInfo clientInfo) {
+                clientInfo.mClientIds.delete(clientId);
+                clientInfo.mClientRequests.delete(clientId);
+                mIdToClientInfoMap.remove(globalId);
+                maybeScheduleStop();
+            }
+
+            @Override
+            public boolean processMessage(Message msg) {
+                final ClientInfo clientInfo;
+                final int id;
+                final int clientId = msg.arg2;
+                final ListenerArgs args;
+                switch (msg.what) {
+                    case NsdManager.DISABLE:
+                        //TODO: cleanup clients
+                        transitionTo(mDisabledState);
+                        break;
+                    case NsdManager.DISCOVER_SERVICES:
+                        if (DBG) Slog.d(TAG, "Discover services");
+                        args = (ListenerArgs) msg.obj;
+                        clientInfo = mClients.get(args.connector);
+
+                        if (requestLimitReached(clientInfo)) {
+                            clientInfo.onDiscoverServicesFailed(
+                                    clientId, NsdManager.FAILURE_MAX_LIMIT);
+                            break;
+                        }
+
+                        maybeStartDaemon();
+                        id = getUniqueId();
+                        if (discoverServices(id, args.serviceInfo.getServiceType())) {
+                            if (DBG) {
+                                Slog.d(TAG, "Discover " + msg.arg2 + " " + id +
+                                        args.serviceInfo.getServiceType());
+                            }
+                            storeRequestMap(clientId, id, clientInfo, msg.what);
+                            clientInfo.onDiscoverServicesStarted(clientId, args.serviceInfo);
+                        } else {
+                            stopServiceDiscovery(id);
+                            clientInfo.onDiscoverServicesFailed(clientId,
+                                    NsdManager.FAILURE_INTERNAL_ERROR);
+                        }
+                        break;
+                    case NsdManager.STOP_DISCOVERY:
+                        if (DBG) Slog.d(TAG, "Stop service discovery");
+                        args = (ListenerArgs) msg.obj;
+                        clientInfo = mClients.get(args.connector);
+
+                        try {
+                            id = clientInfo.mClientIds.get(clientId);
+                        } catch (NullPointerException e) {
+                            clientInfo.onStopDiscoveryFailed(
+                                    clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                            break;
+                        }
+                        removeRequestMap(clientId, id, clientInfo);
+                        if (stopServiceDiscovery(id)) {
+                            clientInfo.onStopDiscoverySucceeded(clientId);
+                        } else {
+                            clientInfo.onStopDiscoveryFailed(
+                                    clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                        }
+                        break;
+                    case NsdManager.REGISTER_SERVICE:
+                        if (DBG) Slog.d(TAG, "Register service");
+                        args = (ListenerArgs) msg.obj;
+                        clientInfo = mClients.get(args.connector);
+                        if (requestLimitReached(clientInfo)) {
+                            clientInfo.onRegisterServiceFailed(
+                                    clientId, NsdManager.FAILURE_MAX_LIMIT);
+                            break;
+                        }
+
+                        maybeStartDaemon();
+                        id = getUniqueId();
+                        if (registerService(id, args.serviceInfo)) {
+                            if (DBG) Slog.d(TAG, "Register " + clientId + " " + id);
+                            storeRequestMap(clientId, id, clientInfo, msg.what);
+                            // Return success after mDns reports success
+                        } else {
+                            unregisterService(id);
+                            clientInfo.onRegisterServiceFailed(
+                                    clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                        }
+                        break;
+                    case NsdManager.UNREGISTER_SERVICE:
+                        if (DBG) Slog.d(TAG, "unregister service");
+                        args = (ListenerArgs) msg.obj;
+                        clientInfo = mClients.get(args.connector);
+                        if (clientInfo == null) {
+                            Slog.e(TAG, "Unknown connector in unregistration");
+                            break;
+                        }
+                        id = clientInfo.mClientIds.get(clientId);
+                        removeRequestMap(clientId, id, clientInfo);
+                        if (unregisterService(id)) {
+                            clientInfo.onUnregisterServiceSucceeded(clientId);
+                        } else {
+                            clientInfo.onUnregisterServiceFailed(
+                                    clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                        }
+                        break;
+                    case NsdManager.RESOLVE_SERVICE:
+                        if (DBG) Slog.d(TAG, "Resolve service");
+                        args = (ListenerArgs) msg.obj;
+                        clientInfo = mClients.get(args.connector);
+
+                        if (clientInfo.mResolvedService != null) {
+                            clientInfo.onResolveServiceFailed(
+                                    clientId, NsdManager.FAILURE_ALREADY_ACTIVE);
+                            break;
+                        }
+
+                        maybeStartDaemon();
+                        id = getUniqueId();
+                        if (resolveService(id, args.serviceInfo)) {
+                            clientInfo.mResolvedService = new NsdServiceInfo();
+                            storeRequestMap(clientId, id, clientInfo, msg.what);
+                        } else {
+                            clientInfo.onResolveServiceFailed(
+                                    clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                        }
+                        break;
+                    case NsdManager.NATIVE_DAEMON_EVENT:
+                        NativeEvent event = (NativeEvent) msg.obj;
+                        if (!handleNativeEvent(event.code, event.raw, event.cooked)) {
+                            return NOT_HANDLED;
+                        }
+                        break;
+                    default:
+                        return NOT_HANDLED;
+                }
+                return HANDLED;
+            }
+
+            private boolean handleNativeEvent(int code, String raw, String[] cooked) {
+                NsdServiceInfo servInfo;
+                int id = Integer.parseInt(cooked[1]);
+                ClientInfo clientInfo = mIdToClientInfoMap.get(id);
+                if (clientInfo == null) {
+                    String name = NativeResponseCode.nameOf(code);
+                    Slog.e(TAG, String.format("id %d for %s has no client mapping", id, name));
+                    return false;
+                }
+
+                /* This goes in response as msg.arg2 */
+                int clientId = clientInfo.getClientId(id);
+                if (clientId < 0) {
+                    // This can happen because of race conditions. For example,
+                    // SERVICE_FOUND may race with STOP_SERVICE_DISCOVERY,
+                    // and we may get in this situation.
+                    String name = NativeResponseCode.nameOf(code);
+                    Slog.d(TAG, String.format(
+                            "Notification %s for listener id %d that is no longer active",
+                            name, id));
+                    return false;
+                }
+                if (DBG) {
+                    String name = NativeResponseCode.nameOf(code);
+                    Slog.d(TAG, String.format("Native daemon message %s: %s", name, raw));
+                }
+                switch (code) {
+                    case NativeResponseCode.SERVICE_FOUND:
+                        /* NNN uniqueId serviceName regType domain */
+                        servInfo = new NsdServiceInfo(cooked[2], cooked[3]);
+                        clientInfo.onServiceFound(clientId, servInfo);
+                        break;
+                    case NativeResponseCode.SERVICE_LOST:
+                        /* NNN uniqueId serviceName regType domain */
+                        servInfo = new NsdServiceInfo(cooked[2], cooked[3]);
+                        clientInfo.onServiceLost(clientId, servInfo);
+                        break;
+                    case NativeResponseCode.SERVICE_DISCOVERY_FAILED:
+                        /* NNN uniqueId errorCode */
+                        clientInfo.onDiscoverServicesFailed(
+                                clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                        break;
+                    case NativeResponseCode.SERVICE_REGISTERED:
+                        /* NNN regId serviceName regType */
+                        servInfo = new NsdServiceInfo(cooked[2], null);
+                        clientInfo.onRegisterServiceSucceeded(clientId, servInfo);
+                        break;
+                    case NativeResponseCode.SERVICE_REGISTRATION_FAILED:
+                        /* NNN regId errorCode */
+                        clientInfo.onRegisterServiceFailed(
+                                clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                        break;
+                    case NativeResponseCode.SERVICE_UPDATED:
+                        /* NNN regId */
+                        break;
+                    case NativeResponseCode.SERVICE_UPDATE_FAILED:
+                        /* NNN regId errorCode */
+                        break;
+                    case NativeResponseCode.SERVICE_RESOLVED:
+                        /* NNN resolveId fullName hostName port txtlen txtdata */
+                        int index = 0;
+                        while (index < cooked[2].length() && cooked[2].charAt(index) != '.') {
+                            if (cooked[2].charAt(index) == '\\') {
+                                ++index;
+                            }
+                            ++index;
+                        }
+                        if (index >= cooked[2].length()) {
+                            Slog.e(TAG, "Invalid service found " + raw);
+                            break;
+                        }
+                        String name = cooked[2].substring(0, index);
+                        String rest = cooked[2].substring(index);
+                        String type = rest.replace(".local.", "");
+
+                        name = unescape(name);
+
+                        clientInfo.mResolvedService.setServiceName(name);
+                        clientInfo.mResolvedService.setServiceType(type);
+                        clientInfo.mResolvedService.setPort(Integer.parseInt(cooked[4]));
+                        clientInfo.mResolvedService.setTxtRecords(cooked[6]);
+
+                        stopResolveService(id);
+                        removeRequestMap(clientId, id, clientInfo);
+
+                        int id2 = getUniqueId();
+                        if (getAddrInfo(id2, cooked[3])) {
+                            storeRequestMap(clientId, id2, clientInfo, NsdManager.RESOLVE_SERVICE);
+                        } else {
+                            clientInfo.onResolveServiceFailed(
+                                    clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                            clientInfo.mResolvedService = null;
+                        }
+                        break;
+                    case NativeResponseCode.SERVICE_RESOLUTION_FAILED:
+                        /* NNN resolveId errorCode */
+                        stopResolveService(id);
+                        removeRequestMap(clientId, id, clientInfo);
+                        clientInfo.mResolvedService = null;
+                        clientInfo.onResolveServiceFailed(
+                                clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                        break;
+                    case NativeResponseCode.SERVICE_GET_ADDR_FAILED:
+                        /* NNN resolveId errorCode */
+                        stopGetAddrInfo(id);
+                        removeRequestMap(clientId, id, clientInfo);
+                        clientInfo.mResolvedService = null;
+                        clientInfo.onResolveServiceFailed(
+                                clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                        break;
+                    case NativeResponseCode.SERVICE_GET_ADDR_SUCCESS:
+                        /* NNN resolveId hostname ttl addr */
+                        try {
+                            clientInfo.mResolvedService.setHost(InetAddress.getByName(cooked[4]));
+                            clientInfo.onResolveServiceSucceeded(
+                                    clientId, clientInfo.mResolvedService);
+                        } catch (java.net.UnknownHostException e) {
+                            clientInfo.onResolveServiceFailed(
+                                    clientId, NsdManager.FAILURE_INTERNAL_ERROR);
+                        }
+                        stopGetAddrInfo(id);
+                        removeRequestMap(clientId, id, clientInfo);
+                        clientInfo.mResolvedService = null;
+                        break;
+                    default:
+                        return false;
+                }
+                return true;
+            }
+       }
+    }
+
+    private String unescape(String s) {
+        StringBuilder sb = new StringBuilder(s.length());
+        for (int i = 0; i < s.length(); ++i) {
+            char c = s.charAt(i);
+            if (c == '\\') {
+                if (++i >= s.length()) {
+                    Slog.e(TAG, "Unexpected end of escape sequence in: " + s);
+                    break;
+                }
+                c = s.charAt(i);
+                if (c != '.' && c != '\\') {
+                    if (i + 2 >= s.length()) {
+                        Slog.e(TAG, "Unexpected end of escape sequence in: " + s);
+                        break;
+                    }
+                    c = (char) ((c-'0') * 100 + (s.charAt(i+1)-'0') * 10 + (s.charAt(i+2)-'0'));
+                    i += 2;
+                }
+            }
+            sb.append(c);
+        }
+        return sb.toString();
+    }
+
+    @VisibleForTesting
+    NsdService(Context ctx, NsdSettings settings, Handler handler,
+            DaemonConnectionSupplier fn, long cleanupDelayMs) {
+        mCleanupDelayMs = cleanupDelayMs;
+        mContext = ctx;
+        mNsdSettings = settings;
+        mNsdStateMachine = new NsdStateMachine(TAG, handler);
+        mNsdStateMachine.start();
+        mDaemonCallback = new NativeCallbackReceiver();
+        mDaemon = fn.get(mDaemonCallback);
+    }
+
+    public static NsdService create(Context context) throws InterruptedException {
+        NsdSettings settings = NsdSettings.makeDefault(context);
+        HandlerThread thread = new HandlerThread(TAG);
+        thread.start();
+        Handler handler = new Handler(thread.getLooper());
+        NsdService service = new NsdService(context, settings, handler,
+                DaemonConnection::new, CLEANUP_DELAY_MS);
+        service.mDaemonCallback.awaitConnection();
+        return service;
+    }
+
+    @Override
+    public INsdServiceConnector connect(INsdManagerCallback cb) {
+        mContext.enforceCallingOrSelfPermission(android.Manifest.permission.INTERNET, "NsdService");
+        final INsdServiceConnector connector = new NsdServiceConnector();
+        mNsdStateMachine.sendMessage(mNsdStateMachine.obtainMessage(
+                NsdManager.REGISTER_CLIENT, new Pair<>(connector, cb)));
+        return connector;
+    }
+
+    private static class ListenerArgs {
+        public final NsdServiceConnector connector;
+        public final NsdServiceInfo serviceInfo;
+        ListenerArgs(NsdServiceConnector connector, NsdServiceInfo serviceInfo) {
+            this.connector = connector;
+            this.serviceInfo = serviceInfo;
+        }
+    }
+
+    private class NsdServiceConnector extends INsdServiceConnector.Stub
+            implements IBinder.DeathRecipient  {
+        @Override
+        public void registerService(int listenerKey, NsdServiceInfo serviceInfo) {
+            mNsdStateMachine.sendMessage(mNsdStateMachine.obtainMessage(
+                    NsdManager.REGISTER_SERVICE, 0, listenerKey,
+                    new ListenerArgs(this, serviceInfo)));
+        }
+
+        @Override
+        public void unregisterService(int listenerKey) {
+            mNsdStateMachine.sendMessage(mNsdStateMachine.obtainMessage(
+                    NsdManager.UNREGISTER_SERVICE, 0, listenerKey,
+                    new ListenerArgs(this, null)));
+        }
+
+        @Override
+        public void discoverServices(int listenerKey, NsdServiceInfo serviceInfo) {
+            mNsdStateMachine.sendMessage(mNsdStateMachine.obtainMessage(
+                    NsdManager.DISCOVER_SERVICES, 0, listenerKey,
+                    new ListenerArgs(this, serviceInfo)));
+        }
+
+        @Override
+        public void stopDiscovery(int listenerKey) {
+            mNsdStateMachine.sendMessage(mNsdStateMachine.obtainMessage(
+                    NsdManager.STOP_DISCOVERY, 0, listenerKey, new ListenerArgs(this, null)));
+        }
+
+        @Override
+        public void resolveService(int listenerKey, NsdServiceInfo serviceInfo) {
+            mNsdStateMachine.sendMessage(mNsdStateMachine.obtainMessage(
+                    NsdManager.RESOLVE_SERVICE, 0, listenerKey,
+                    new ListenerArgs(this, serviceInfo)));
+        }
+
+        @Override
+        public void startDaemon() {
+            mNsdStateMachine.sendMessage(mNsdStateMachine.obtainMessage(
+                    NsdManager.DAEMON_STARTUP, new ListenerArgs(this, null)));
+        }
+
+        @Override
+        public void binderDied() {
+            mNsdStateMachine.sendMessage(
+                    mNsdStateMachine.obtainMessage(NsdManager.UNREGISTER_CLIENT, this));
+        }
+    }
+
+    private void notifyEnabled(boolean isEnabled) {
+        mNsdStateMachine.sendMessage(isEnabled ? NsdManager.ENABLE : NsdManager.DISABLE);
+    }
+
+    private void sendNsdStateChangeBroadcast(boolean isEnabled) {
+        final Intent intent = new Intent(NsdManager.ACTION_NSD_STATE_CHANGED);
+        intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);
+        int nsdState = isEnabled ? NsdManager.NSD_STATE_ENABLED : NsdManager.NSD_STATE_DISABLED;
+        intent.putExtra(NsdManager.EXTRA_NSD_STATE, nsdState);
+        mContext.sendStickyBroadcastAsUser(intent, UserHandle.ALL);
+    }
+
+    private boolean isNsdEnabled() {
+        boolean ret = mNsdSettings.isEnabled();
+        if (DBG) {
+            Slog.d(TAG, "Network service discovery is " + (ret ? "enabled" : "disabled"));
+        }
+        return ret;
+    }
+
+    private int getUniqueId() {
+        if (++mUniqueId == INVALID_ID) return ++mUniqueId;
+        return mUniqueId;
+    }
+
+    /* These should be in sync with system/netd/server/ResponseCode.h */
+    static final class NativeResponseCode {
+        public static final int SERVICE_DISCOVERY_FAILED    =   602;
+        public static final int SERVICE_FOUND               =   603;
+        public static final int SERVICE_LOST                =   604;
+
+        public static final int SERVICE_REGISTRATION_FAILED =   605;
+        public static final int SERVICE_REGISTERED          =   606;
+
+        public static final int SERVICE_RESOLUTION_FAILED   =   607;
+        public static final int SERVICE_RESOLVED            =   608;
+
+        public static final int SERVICE_UPDATED             =   609;
+        public static final int SERVICE_UPDATE_FAILED       =   610;
+
+        public static final int SERVICE_GET_ADDR_FAILED     =   611;
+        public static final int SERVICE_GET_ADDR_SUCCESS    =   612;
+
+        private static final SparseArray<String> CODE_NAMES = new SparseArray<>();
+        static {
+            CODE_NAMES.put(SERVICE_DISCOVERY_FAILED, "SERVICE_DISCOVERY_FAILED");
+            CODE_NAMES.put(SERVICE_FOUND, "SERVICE_FOUND");
+            CODE_NAMES.put(SERVICE_LOST, "SERVICE_LOST");
+            CODE_NAMES.put(SERVICE_REGISTRATION_FAILED, "SERVICE_REGISTRATION_FAILED");
+            CODE_NAMES.put(SERVICE_REGISTERED, "SERVICE_REGISTERED");
+            CODE_NAMES.put(SERVICE_RESOLUTION_FAILED, "SERVICE_RESOLUTION_FAILED");
+            CODE_NAMES.put(SERVICE_RESOLVED, "SERVICE_RESOLVED");
+            CODE_NAMES.put(SERVICE_UPDATED, "SERVICE_UPDATED");
+            CODE_NAMES.put(SERVICE_UPDATE_FAILED, "SERVICE_UPDATE_FAILED");
+            CODE_NAMES.put(SERVICE_GET_ADDR_FAILED, "SERVICE_GET_ADDR_FAILED");
+            CODE_NAMES.put(SERVICE_GET_ADDR_SUCCESS, "SERVICE_GET_ADDR_SUCCESS");
+        }
+
+        static String nameOf(int code) {
+            String name = CODE_NAMES.get(code);
+            if (name == null) {
+                return Integer.toString(code);
+            }
+            return name;
+        }
+    }
+
+    private class NativeEvent {
+        final int code;
+        final String raw;
+        final String[] cooked;
+
+        NativeEvent(int code, String raw, String[] cooked) {
+            this.code = code;
+            this.raw = raw;
+            this.cooked = cooked;
+        }
+    }
+
+    class NativeCallbackReceiver implements INativeDaemonConnectorCallbacks {
+        private final CountDownLatch connected = new CountDownLatch(1);
+
+        public void awaitConnection() throws InterruptedException {
+            connected.await();
+        }
+
+        @Override
+        public void onDaemonConnected() {
+            connected.countDown();
+        }
+
+        @Override
+        public boolean onCheckHoldWakeLock(int code) {
+            return false;
+        }
+
+        @Override
+        public boolean onEvent(int code, String raw, String[] cooked) {
+            // TODO: NDC translates a message to a callback, we could enhance NDC to
+            // directly interact with a state machine through messages
+            NativeEvent event = new NativeEvent(code, raw, cooked);
+            mNsdStateMachine.sendMessage(NsdManager.NATIVE_DAEMON_EVENT, event);
+            return true;
+        }
+    }
+
+    interface DaemonConnectionSupplier {
+        DaemonConnection get(NativeCallbackReceiver callback);
+    }
+
+    @VisibleForTesting
+    public static class DaemonConnection {
+        final NativeDaemonConnector mNativeConnector;
+        boolean mIsStarted = false;
+
+        DaemonConnection(NativeCallbackReceiver callback) {
+            mNativeConnector = new NativeDaemonConnector(callback, "mdns", 10, MDNS_TAG, 25, null);
+            new Thread(mNativeConnector, MDNS_TAG).start();
+        }
+
+        /**
+         * Executes the specified cmd on the daemon.
+         */
+        public boolean execute(Object... args) {
+            if (DBG) {
+                Slog.d(TAG, "mdnssd " + Arrays.toString(args));
+            }
+            try {
+                mNativeConnector.execute("mdnssd", args);
+            } catch (NativeDaemonConnectorException e) {
+                Slog.e(TAG, "Failed to execute mdnssd " + Arrays.toString(args), e);
+                return false;
+            }
+            return true;
+        }
+
+        /**
+         * Starts the daemon if it is not already started.
+         */
+        public void maybeStart() {
+            if (mIsStarted) {
+                return;
+            }
+            execute("start-service");
+            mIsStarted = true;
+        }
+
+        /**
+         * Stops the daemon if it is started.
+         */
+        public void maybeStop() {
+            if (!mIsStarted) {
+                return;
+            }
+            execute("stop-service");
+            mIsStarted = false;
+        }
+    }
+
+    private boolean registerService(int regId, NsdServiceInfo service) {
+        if (DBG) {
+            Slog.d(TAG, "registerService: " + regId + " " + service);
+        }
+        String name = service.getServiceName();
+        String type = service.getServiceType();
+        int port = service.getPort();
+        byte[] textRecord = service.getTxtRecord();
+        String record = Base64.encodeToString(textRecord, Base64.DEFAULT).replace("\n", "");
+        return mDaemon.execute("register", regId, name, type, port, record);
+    }
+
+    private boolean unregisterService(int regId) {
+        return mDaemon.execute("stop-register", regId);
+    }
+
+    private boolean updateService(int regId, DnsSdTxtRecord t) {
+        if (t == null) {
+            return false;
+        }
+        return mDaemon.execute("update", regId, t.size(), t.getRawData());
+    }
+
+    private boolean discoverServices(int discoveryId, String serviceType) {
+        return mDaemon.execute("discover", discoveryId, serviceType);
+    }
+
+    private boolean stopServiceDiscovery(int discoveryId) {
+        return mDaemon.execute("stop-discover", discoveryId);
+    }
+
+    private boolean resolveService(int resolveId, NsdServiceInfo service) {
+        String name = service.getServiceName();
+        String type = service.getServiceType();
+        return mDaemon.execute("resolve", resolveId, name, type, "local.");
+    }
+
+    private boolean stopResolveService(int resolveId) {
+        return mDaemon.execute("stop-resolve", resolveId);
+    }
+
+    private boolean getAddrInfo(int resolveId, String hostname) {
+        return mDaemon.execute("getaddrinfo", resolveId, hostname);
+    }
+
+    private boolean stopGetAddrInfo(int resolveId) {
+        return mDaemon.execute("stop-getaddrinfo", resolveId);
+    }
+
+    @Override
+    public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
+        if (!DumpUtils.checkDumpPermission(mContext, TAG, pw)) return;
+
+        for (ClientInfo client : mClients.values()) {
+            pw.println("Client Info");
+            pw.println(client);
+        }
+
+        mNsdStateMachine.dump(fd, pw, args);
+    }
+
+    /* Information tracked per client */
+    private class ClientInfo {
+
+        private static final int MAX_LIMIT = 10;
+        private final INsdManagerCallback mCb;
+        /* Remembers a resolved service until getaddrinfo completes */
+        private NsdServiceInfo mResolvedService;
+
+        /* A map from client id to unique id sent to mDns */
+        private final SparseIntArray mClientIds = new SparseIntArray();
+
+        /* A map from client id to the type of the request we had received */
+        private final SparseIntArray mClientRequests = new SparseIntArray();
+
+        // The target SDK of this client < Build.VERSION_CODES.S
+        private boolean mIsLegacy = false;
+
+        private ClientInfo(INsdManagerCallback cb) {
+            mCb = cb;
+            if (DBG) Slog.d(TAG, "New client");
+        }
+
+        @Override
+        public String toString() {
+            StringBuilder sb = new StringBuilder();
+            sb.append("mResolvedService ").append(mResolvedService).append("\n");
+            sb.append("mIsLegacy ").append(mIsLegacy).append("\n");
+            for(int i = 0; i< mClientIds.size(); i++) {
+                int clientID = mClientIds.keyAt(i);
+                sb.append("clientId ").append(clientID).
+                    append(" mDnsId ").append(mClientIds.valueAt(i)).
+                    append(" type ").append(mClientRequests.get(clientID)).append("\n");
+            }
+            return sb.toString();
+        }
+
+        private boolean isLegacy() {
+            return mIsLegacy;
+        }
+
+        private void setLegacy() {
+            mIsLegacy = true;
+        }
+
+        // Remove any pending requests from the global map when we get rid of a client,
+        // and send cancellations to the daemon.
+        private void expungeAllRequests() {
+            int globalId, clientId, i;
+            // TODO: to keep handler responsive, do not clean all requests for that client at once.
+            for (i = 0; i < mClientIds.size(); i++) {
+                clientId = mClientIds.keyAt(i);
+                globalId = mClientIds.valueAt(i);
+                mIdToClientInfoMap.remove(globalId);
+                if (DBG) Slog.d(TAG, "Terminating client-ID " + clientId +
+                        " global-ID " + globalId + " type " + mClientRequests.get(clientId));
+                switch (mClientRequests.get(clientId)) {
+                    case NsdManager.DISCOVER_SERVICES:
+                        stopServiceDiscovery(globalId);
+                        break;
+                    case NsdManager.RESOLVE_SERVICE:
+                        stopResolveService(globalId);
+                        break;
+                    case NsdManager.REGISTER_SERVICE:
+                        unregisterService(globalId);
+                        break;
+                    default:
+                        break;
+                }
+            }
+            mClientIds.clear();
+            mClientRequests.clear();
+        }
+
+        // mClientIds is a sparse array of listener id -> mDnsClient id.  For a given mDnsClient id,
+        // return the corresponding listener id.  mDnsClient id is also called a global id.
+        private int getClientId(final int globalId) {
+            int idx = mClientIds.indexOfValue(globalId);
+            if (idx < 0) {
+                return idx;
+            }
+            return mClientIds.keyAt(idx);
+        }
+
+        void onDiscoverServicesStarted(int listenerKey, NsdServiceInfo info) {
+            try {
+                mCb.onDiscoverServicesStarted(listenerKey, info);
+            } catch (RemoteException e) {
+                Log.e(TAG, "Error calling onDiscoverServicesStarted", e);
+            }
+        }
+
+        void onDiscoverServicesFailed(int listenerKey, int error) {
+            try {
+                mCb.onDiscoverServicesFailed(listenerKey, error);
+            } catch (RemoteException e) {
+                Log.e(TAG, "Error calling onDiscoverServicesFailed", e);
+            }
+        }
+
+        void onServiceFound(int listenerKey, NsdServiceInfo info) {
+            try {
+                mCb.onServiceFound(listenerKey, info);
+            } catch (RemoteException e) {
+                Log.e(TAG, "Error calling onServiceFound(", e);
+            }
+        }
+
+        void onServiceLost(int listenerKey, NsdServiceInfo info) {
+            try {
+                mCb.onServiceLost(listenerKey, info);
+            } catch (RemoteException e) {
+                Log.e(TAG, "Error calling onServiceLost(", e);
+            }
+        }
+
+        void onStopDiscoveryFailed(int listenerKey, int error) {
+            try {
+                mCb.onStopDiscoveryFailed(listenerKey, error);
+            } catch (RemoteException e) {
+                Log.e(TAG, "Error calling onStopDiscoveryFailed", e);
+            }
+        }
+
+        void onStopDiscoverySucceeded(int listenerKey) {
+            try {
+                mCb.onStopDiscoverySucceeded(listenerKey);
+            } catch (RemoteException e) {
+                Log.e(TAG, "Error calling onStopDiscoverySucceeded", e);
+            }
+        }
+
+        void onRegisterServiceFailed(int listenerKey, int error) {
+            try {
+                mCb.onRegisterServiceFailed(listenerKey, error);
+            } catch (RemoteException e) {
+                Log.e(TAG, "Error calling onRegisterServiceFailed", e);
+            }
+        }
+
+        void onRegisterServiceSucceeded(int listenerKey, NsdServiceInfo info) {
+            try {
+                mCb.onRegisterServiceSucceeded(listenerKey, info);
+            } catch (RemoteException e) {
+                Log.e(TAG, "Error calling onRegisterServiceSucceeded", e);
+            }
+        }
+
+        void onUnregisterServiceFailed(int listenerKey, int error) {
+            try {
+                mCb.onUnregisterServiceFailed(listenerKey, error);
+            } catch (RemoteException e) {
+                Log.e(TAG, "Error calling onUnregisterServiceFailed", e);
+            }
+        }
+
+        void onUnregisterServiceSucceeded(int listenerKey) {
+            try {
+                mCb.onUnregisterServiceSucceeded(listenerKey);
+            } catch (RemoteException e) {
+                Log.e(TAG, "Error calling onUnregisterServiceSucceeded", e);
+            }
+        }
+
+        void onResolveServiceFailed(int listenerKey, int error) {
+            try {
+                mCb.onResolveServiceFailed(listenerKey, error);
+            } catch (RemoteException e) {
+                Log.e(TAG, "Error calling onResolveServiceFailed", e);
+            }
+        }
+
+        void onResolveServiceSucceeded(int listenerKey, NsdServiceInfo info) {
+            try {
+                mCb.onResolveServiceSucceeded(listenerKey, info);
+            } catch (RemoteException e) {
+                Log.e(TAG, "Error calling onResolveServiceSucceeded", e);
+            }
+        }
+    }
+
+    /**
+     * Interface which encapsulates dependencies of NsdService that are hard to mock, hard to
+     * override, or have side effects on global state in unit tests.
+     */
+    @VisibleForTesting
+    public interface NsdSettings {
+        boolean isEnabled();
+        void putEnabledStatus(boolean isEnabled);
+        void registerContentObserver(Uri uri, ContentObserver observer);
+
+        static NsdSettings makeDefault(Context context) {
+            final ContentResolver resolver = context.getContentResolver();
+            return new NsdSettings() {
+                @Override
+                public boolean isEnabled() {
+                    return Settings.Global.getInt(resolver, Settings.Global.NSD_ON, 1) == 1;
+                }
+
+                @Override
+                public void putEnabledStatus(boolean isEnabled) {
+                    Settings.Global.putInt(resolver, Settings.Global.NSD_ON, isEnabled ? 1 : 0);
+                }
+
+                @Override
+                public void registerContentObserver(Uri uri, ContentObserver observer) {
+                    resolver.registerContentObserver(uri, false, observer);
+                }
+            };
+        }
+    }
+}