diff --git a/staticlibs/Android.bp b/staticlibs/Android.bp
index 0f8dda0..4b15b16 100644
--- a/staticlibs/Android.bp
+++ b/staticlibs/Android.bp
@@ -27,10 +27,86 @@
 // included in the bootclasspath, they could incorrectly be included in the SDK documentation even
 // though they are not in the current.txt files.
 
+java_library {
+  name: "net-utils-device-common",
+  srcs: [
+      "device/**/*.java",
+      // This library is used by system modules, for which the system health impact of Kotlin
+      // has not yet been evaluated.
+      // "src_devicecommon/**/*.kt",
+      ":framework-annotations",
+  ],
+  sdk_version: "system_current",
+  min_sdk_version: "29",
+  target_sdk_version: "30",
+  apex_available: [
+      "//apex_available:anyapex",
+      "//apex_available:platform",
+  ],
+  visibility: [
+        "//frameworks/base/packages/Tethering",
+        "//frameworks/opt/net/ike",
+        "//frameworks/opt/net/wifi/service",
+        "//frameworks/opt/net/telephony",
+        "//packages/modules/NetworkStack",
+        "//packages/modules/CaptivePortalLogin",
+        "//frameworks/libs/net/common/tests:__subpackages__",
+  ],
+  libs: [
+      "androidx.annotation_annotation",
+  ],
+}
+
+java_library {
+  // Consider using net-tests-utils instead if writing device code.
+  // That library has a lot more useful tools into it for users that
+  // work on Android and includes this lib.
+  name: "net-tests-utils-host-device-common",
+  srcs: [
+      "hostdevice/**/*.java",
+      "hostdevice/**/*.kt",
+  ],
+  host_supported: true,
+  visibility: [
+      "//frameworks/libs/net/common/tests:__subpackages__",
+  ],
+  static_libs: [
+      "kotlin-test"
+  ]
+}
+
+java_defaults {
+    name: "lib_mockito_extended",
+    static_libs: [
+        "mockito-target-extended-minus-junit4"
+    ],
+    jni_libs: [
+        "libdexmakerjvmtiagent",
+        "libstaticjvmtiagent",
+    ],
+}
+
+java_library {
+    name: "net-tests-utils",
+    srcs: [
+        "devicetests/**/*.java",
+        "devicetests/**/*.kt",
+    ],
+    defaults: ["lib_mockito_extended"],
+    libs: [
+        "androidx.annotation_annotation",
+    ],
+    static_libs: [
+        "androidx.test.ext.junit",
+        "net-tests-utils-host-device-common",
+        "net-utils-device-common",
+    ],
+}
+
 filegroup {
     name: "net-utils-framework-common-srcs",
-    srcs: ["src_frameworkcommon/**/*.java"],
-    path: "src_frameworkcommon",
+    srcs: ["framework/**/*.java"],
+    path: "framework",
     visibility: ["//frameworks/base"],
 }
 
@@ -49,7 +125,7 @@
         "//frameworks/base/packages/Tethering",
         "//frameworks/opt/net/ike",
         "//frameworks/opt/telephony",
-        "//packages/modules/NetworkStack",
+        "//packages/modules/NetworkStack:__subpackages__",
         "//packages/modules/CaptivePortalLogin",
         "//frameworks/libs/net/common/tests:__subpackages__",
     ]
@@ -58,17 +134,12 @@
 java_library {
     name: "net-utils-services-common",
     srcs: [
-        "src_servicescommon/**/*.java",
+        "device/android/net/NetworkFactory.java",
         ":framework-annotations",
     ],
     sdk_version: "system_current",
     visibility: [
         "//frameworks/base/services/net",
-        "//frameworks/base/packages/Tethering",
-        "//frameworks/opt/net/ike",
-        "//packages/modules/NetworkStack",
-        "//packages/modules/CaptivePortalLogin",
-        "//frameworks/libs/net/common/tests:__subpackages__",
     ],
 }
 
@@ -78,9 +149,9 @@
     name: "net-utils-telephony-common-srcs",
     srcs: [
         // Any class here *must* have a corresponding jarjar rule in the telephony build rules.
-        "src_servicescommon/android/net/NetworkFactory.java",
+        "device/android/net/NetworkFactory.java",
     ],
-    path: "src_servicescommon",
+    path: "device",
     visibility: [
         "//frameworks/opt/telephony",
     ],
@@ -92,11 +163,11 @@
 filegroup {
     name: "net-utils-framework-wifi-common-srcs",
     srcs: [
-        "src_frameworkcommon/android/net/util/nsd/DnsSdTxtRecord.java",
-        "src_frameworkcommon/android/net/util/MacAddressUtils.java",
-        "src_frameworkcommon/com/android/net/module/util/**/*.java",
+        "framework/android/net/util/nsd/DnsSdTxtRecord.java",
+        "framework/android/net/util/MacAddressUtils.java",
+        "framework/com/android/net/module/util/**/*.java",
     ],
-    path: "src_frameworkcommon",
+    path: "framework",
     visibility: [
         "//frameworks/base",
     ],
@@ -108,8 +179,8 @@
 filegroup {
     name: "net-utils-wifi-service-common-srcs",
     srcs: [
-        "src_frameworkcommon/android/net/util/NetUtils.java",
-        "src_servicescommon/android/net/NetworkFactory.java",
+       "device/android/net/NetworkFactory.java",
+       "framework/android/net/util/NetUtils.java",
     ],
     visibility: [
         "//frameworks/opt/net/wifi/service",
diff --git a/staticlibs/src_servicescommon/android/net/NetworkFactory.java b/staticlibs/device/android/net/NetworkFactory.java
similarity index 100%
rename from staticlibs/src_servicescommon/android/net/NetworkFactory.java
rename to staticlibs/device/android/net/NetworkFactory.java
diff --git a/staticlibs/device/android/net/util/FdEventsReader.java b/staticlibs/device/android/net/util/FdEventsReader.java
new file mode 100644
index 0000000..a5714aa
--- /dev/null
+++ b/staticlibs/device/android/net/util/FdEventsReader.java
@@ -0,0 +1,269 @@
+/*
+ * Copyright (C) 2016 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.
+ */
+
+// TODO : move this and PacketReader to com.android.net.module.util.
+package android.net.util;
+
+import static android.os.MessageQueue.OnFileDescriptorEventListener.EVENT_ERROR;
+import static android.os.MessageQueue.OnFileDescriptorEventListener.EVENT_INPUT;
+
+import android.os.Handler;
+import android.os.Looper;
+import android.os.MessageQueue;
+import android.system.ErrnoException;
+import android.system.OsConstants;
+import android.util.Log;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+
+import com.android.internal.annotations.VisibleForTesting;
+
+import java.io.FileDescriptor;
+import java.io.IOException;
+
+
+/**
+ * This class encapsulates the mechanics of registering a file descriptor
+ * with a thread's Looper and handling read events (and errors).
+ *
+ * Subclasses MUST implement createFd() and SHOULD override handlePacket(). They MAY override
+ * onStop() and onStart().
+ *
+ * Subclasses can expect a call life-cycle like the following:
+ *
+ *     [1] when a client calls start(), createFd() is called, followed by the onStart() hook if all
+ *         goes well. Implementations may override onStart() for additional initialization.
+ *
+ *     [2] yield, waiting for read event or error notification:
+ *
+ *             [a] readPacket() && handlePacket()
+ *
+ *             [b] if (no error):
+ *                     goto 2
+ *                 else:
+ *                     goto 3
+ *
+ *     [3] when a client calls stop(), the onStop() hook is called (unless already stopped or never
+ *         started). Implementations may override onStop() for additional cleanup.
+ *
+ * The packet receive buffer is recycled on every read call, so subclasses
+ * should make any copies they would like inside their handlePacket()
+ * implementation.
+ *
+ * All public methods MUST only be called from the same thread with which
+ * the Handler constructor argument is associated.
+ *
+ * @param <BufferType> the type of the buffer used to read data.
+ */
+public abstract class FdEventsReader<BufferType> {
+    private static final int FD_EVENTS = EVENT_INPUT | EVENT_ERROR;
+    private static final int UNREGISTER_THIS_FD = 0;
+
+    @NonNull
+    private final Handler mHandler;
+    @NonNull
+    private final MessageQueue mQueue;
+    @NonNull
+    private final BufferType mBuffer;
+    @Nullable
+    private FileDescriptor mFd;
+    private long mPacketsReceived;
+
+    protected static void closeFd(FileDescriptor fd) {
+        try {
+            SocketUtils.closeSocket(fd);
+        } catch (IOException ignored) {
+        }
+    }
+
+    protected FdEventsReader(@NonNull Handler h, @NonNull BufferType buffer) {
+        mHandler = h;
+        mQueue = mHandler.getLooper().getQueue();
+        mBuffer = buffer;
+    }
+
+    @VisibleForTesting
+    @NonNull
+    protected MessageQueue getMessageQueue() {
+        return mQueue;
+    }
+
+    /** Start this FdEventsReader. */
+    public boolean start() {
+        if (!onCorrectThread()) {
+            throw new IllegalStateException("start() called from off-thread");
+        }
+
+        return createAndRegisterFd();
+    }
+
+    /** Stop this FdEventsReader and destroy the file descriptor. */
+    public void stop() {
+        if (!onCorrectThread()) {
+            throw new IllegalStateException("stop() called from off-thread");
+        }
+
+        unregisterAndDestroyFd();
+    }
+
+    @NonNull
+    public Handler getHandler() {
+        return mHandler;
+    }
+
+    protected abstract int recvBufSize(@NonNull BufferType buffer);
+
+    /** Returns the size of the receive buffer. */
+    public int recvBufSize() {
+        return recvBufSize(mBuffer);
+    }
+
+    /**
+     * Get the number of successful calls to {@link #readPacket(FileDescriptor, Object)}.
+     *
+     * <p>A call was successful if {@link #readPacket(FileDescriptor, Object)} returned a value > 0.
+     */
+    public final long numPacketsReceived() {
+        return mPacketsReceived;
+    }
+
+    /**
+     * Subclasses MUST create the listening socket here, including setting all desired socket
+     * options, interface or address/port binding, etc. The socket MUST be created nonblocking.
+     */
+    @Nullable
+    protected abstract FileDescriptor createFd();
+
+    /**
+     * Implementations MUST return the bytes read or throw an Exception.
+     *
+     * <p>The caller may throw a {@link ErrnoException} with {@link OsConstants#EAGAIN} or
+     * {@link OsConstants#EINTR}, in which case {@link FdEventsReader} will ignore the buffer
+     * contents and respectively wait for further input or retry the read immediately. For all other
+     * exceptions, the {@link FdEventsReader} will be stopped with no more interactions with this
+     * method.
+     */
+    protected abstract int readPacket(@NonNull FileDescriptor fd, @NonNull BufferType buffer)
+            throws Exception;
+
+    /**
+     * Called by the main loop for every packet.  Any desired copies of
+     * |recvbuf| should be made in here, as the underlying byte array is
+     * reused across all reads.
+     */
+    protected void handlePacket(@NonNull BufferType recvbuf, int length) {}
+
+    /**
+     * Called by the main loop to log errors.  In some cases |e| may be null.
+     */
+    protected void logError(@NonNull String msg, @Nullable Exception e) {}
+
+    /**
+     * Called by start(), if successful, just prior to returning.
+     */
+    protected void onStart() {}
+
+    /**
+     * Called by stop() just prior to returning.
+     */
+    protected void onStop() {}
+
+    private boolean createAndRegisterFd() {
+        if (mFd != null) return true;
+
+        try {
+            mFd = createFd();
+        } catch (Exception e) {
+            logError("Failed to create socket: ", e);
+            closeFd(mFd);
+            mFd = null;
+        }
+
+        if (mFd == null) return false;
+
+        getMessageQueue().addOnFileDescriptorEventListener(
+                mFd,
+                FD_EVENTS,
+                (fd, events) -> {
+                    // Always call handleInput() so read/recvfrom are given
+                    // a proper chance to encounter a meaningful errno and
+                    // perhaps log a useful error message.
+                    if (!isRunning() || !handleInput()) {
+                        unregisterAndDestroyFd();
+                        return UNREGISTER_THIS_FD;
+                    }
+                    return FD_EVENTS;
+                });
+        onStart();
+        return true;
+    }
+
+    private boolean isRunning() {
+        return (mFd != null) && mFd.valid();
+    }
+
+    // Keep trying to read until we get EAGAIN/EWOULDBLOCK or some fatal error.
+    private boolean handleInput() {
+        while (isRunning()) {
+            final int bytesRead;
+
+            try {
+                bytesRead = readPacket(mFd, mBuffer);
+                if (bytesRead < 1) {
+                    if (isRunning()) logError("Socket closed, exiting", null);
+                    break;
+                }
+                mPacketsReceived++;
+            } catch (ErrnoException e) {
+                if (e.errno == OsConstants.EAGAIN) {
+                    // We've read everything there is to read this time around.
+                    return true;
+                } else if (e.errno == OsConstants.EINTR) {
+                    continue;
+                } else {
+                    if (isRunning()) logError("readPacket error: ", e);
+                    break;
+                }
+            } catch (Exception e) {
+                if (isRunning()) logError("readPacket error: ", e);
+                break;
+            }
+
+            try {
+                handlePacket(mBuffer, bytesRead);
+            } catch (Exception e) {
+                logError("handlePacket error: ", e);
+                Log.wtf(FdEventsReader.class.getSimpleName(), "Error handling packet", e);
+            }
+        }
+
+        return false;
+    }
+
+    private void unregisterAndDestroyFd() {
+        if (mFd == null) return;
+
+        getMessageQueue().removeOnFileDescriptorEventListener(mFd);
+        closeFd(mFd);
+        mFd = null;
+        onStop();
+    }
+
+    private boolean onCorrectThread() {
+        return (mHandler.getLooper() == Looper.myLooper());
+    }
+}
diff --git a/staticlibs/device/android/net/util/PacketReader.java b/staticlibs/device/android/net/util/PacketReader.java
new file mode 100644
index 0000000..61b3d6e
--- /dev/null
+++ b/staticlibs/device/android/net/util/PacketReader.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2018 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.
+ */
+
+// TODO : move this and FdEventsReader to com.android.net.module.util.
+package android.net.util;
+
+import static java.lang.Math.max;
+
+import android.os.Handler;
+import android.system.Os;
+
+import java.io.FileDescriptor;
+
+/**
+ * Specialization of {@link FdEventsReader} that reads packets into a byte array.
+ *
+ * TODO: rename this class to something more correctly descriptive (something
+ * like [or less horrible than] FdReadEventsHandler?).
+ */
+public abstract class PacketReader extends FdEventsReader<byte[]> {
+
+    public static final int DEFAULT_RECV_BUF_SIZE = 2 * 1024;
+
+    protected PacketReader(Handler h) {
+        this(h, DEFAULT_RECV_BUF_SIZE);
+    }
+
+    protected PacketReader(Handler h, int recvBufSize) {
+        super(h, new byte[max(recvBufSize, DEFAULT_RECV_BUF_SIZE)]);
+    }
+
+    @Override
+    protected final int recvBufSize(byte[] buffer) {
+        return buffer.length;
+    }
+
+    /**
+     * Subclasses MAY override this to change the default read() implementation
+     * in favour of, say, recvfrom().
+     *
+     * Implementations MUST return the bytes read or throw an Exception.
+     */
+    @Override
+    protected int readPacket(FileDescriptor fd, byte[] packetBuffer) throws Exception {
+        return Os.read(fd, packetBuffer, 0, packetBuffer.length);
+    }
+}
diff --git a/staticlibs/devicetests/com/android/testutils/ConcurrentInterpreter.kt b/staticlibs/devicetests/com/android/testutils/ConcurrentInterpreter.kt
new file mode 100644
index 0000000..98464eb
--- /dev/null
+++ b/staticlibs/devicetests/com/android/testutils/ConcurrentInterpreter.kt
@@ -0,0 +1,188 @@
+package com.android.testutils
+
+import android.os.SystemClock
+import java.util.concurrent.CyclicBarrier
+import kotlin.system.measureTimeMillis
+import kotlin.test.assertEquals
+import kotlin.test.assertFails
+import kotlin.test.assertNull
+import kotlin.test.assertTrue
+
+// The table contains pairs associating a regexp with the code to run. The statement is matched
+// against each matcher in sequence and when a match is found the associated code is run, passing
+// it the TrackRecord under test and the result of the regexp match.
+typealias InterpretMatcher<T> = Pair<Regex, (ConcurrentInterpreter<T>, T, MatchResult) -> Any?>
+
+// The default unit of time for interpreted tests
+val INTERPRET_TIME_UNIT = 40L // ms
+
+/**
+ * A small interpreter for testing parallel code. The interpreter will read a list of lines
+ * consisting of "|"-separated statements. Each column runs in a different concurrent thread
+ * and all threads wait for each other in between lines. Each statement is split on ";" then
+ * matched with regular expressions in the instructionTable constant, which contains the
+ * code associated with each statement. The interpreter supports an object being passed to
+ * the interpretTestSpec() method to be passed in each lambda (think about the object under
+ * test), and an optional transform function to be executed on the object at the start of
+ * every thread.
+ *
+ * The time unit is defined in milliseconds by the interpretTimeUnit member, which has a default
+ * value but can be passed to the constructor. Whitespace is ignored.
+ *
+ * The interpretation table has to be passed as an argument. It's a table associating a regexp
+ * with the code that should execute, as a function taking three arguments : the interpreter,
+ * the regexp match, and the object. See the individual tests for the DSL of that test.
+ * Implementors for new interpreting languages are encouraged to look at the defaultInterpretTable
+ * constant below for an example of how to write an interpreting table.
+ * Some expressions already exist by default and can be used by all interpreters. They include :
+ * sleep(x) : sleeps for x time units and returns Unit ; sleep alone means sleep(1)
+ * EXPR = VALUE : asserts that EXPR equals VALUE. EXPR is interpreted. VALUE can either be the
+ *   string "null" or an int. Returns Unit.
+ * EXPR time x..y : measures the time taken by EXPR and asserts it took at least x and at most
+ *   y time units.
+ * EXPR // any text : comments are ignored.
+ */
+open class ConcurrentInterpreter<T>(
+    localInterpretTable: List<InterpretMatcher<T>>,
+    val interpretTimeUnit: Long = INTERPRET_TIME_UNIT
+) {
+    private val interpretTable: List<InterpretMatcher<T>> =
+            localInterpretTable + getDefaultInstructions()
+
+    // Split the line into multiple statements separated by ";" and execute them. Return whatever
+    // the last statement returned.
+    fun interpretMultiple(instr: String, r: T): Any? {
+        return instr.split(";").map { interpret(it.trim(), r) }.last()
+    }
+
+    // Match the statement to a regex and interpret it.
+    fun interpret(instr: String, r: T): Any? {
+        val (matcher, code) =
+                interpretTable.find { instr matches it.first } ?: throw SyntaxException(instr)
+        val match = matcher.matchEntire(instr) ?: throw SyntaxException(instr)
+        return code(this, r, match)
+    }
+
+    // Spins as many threads as needed by the test spec and interpret each program concurrently,
+    // having all threads waiting on a CyclicBarrier after each line.
+    // |lineShift| says how many lines after the call the spec starts. This is used for error
+    // reporting. Unfortunately AFAICT there is no way to get the line of an argument rather
+    // than the line at which the expression starts.
+    fun interpretTestSpec(
+        spec: String,
+        initial: T,
+        lineShift: Int = 0,
+        threadTransform: (T) -> T = { it }
+    ) {
+        // For nice stack traces
+        val callSite = getCallingMethod()
+        val lines = spec.trim().trim('\n').split("\n").map { it.split("|") }
+        // |threads| contains arrays of strings that make up the statements of a thread : in other
+        // words, it's an array that contains a list of statements for each column in the spec.
+        val threadCount = lines[0].size
+        assertTrue(lines.all { it.size == threadCount })
+        val threadInstructions = (0 until threadCount).map { i -> lines.map { it[i].trim() } }
+        val barrier = CyclicBarrier(threadCount)
+        var crash: InterpretException? = null
+        threadInstructions.mapIndexed { threadIndex, instructions ->
+            Thread {
+                val threadLocal = threadTransform(initial)
+                barrier.await()
+                var lineNum = 0
+                instructions.forEach {
+                    if (null != crash) return@Thread
+                    lineNum += 1
+                    try {
+                        interpretMultiple(it, threadLocal)
+                    } catch (e: Throwable) {
+                        // If fail() or some exception was called, the thread will come here ; if
+                        // the exception isn't caught the process will crash, which is not nice for
+                        // testing. Instead, catch the exception, cancel other threads, and report
+                        // nicely. Catch throwable because fail() is AssertionError, which inherits
+                        // from Error.
+                        crash = InterpretException(threadIndex, it,
+                                callSite.lineNumber + lineNum + lineShift,
+                                callSite.className, callSite.methodName, callSite.fileName, e)
+                    }
+                    barrier.await()
+                }
+            }.also { it.start() }
+        }.forEach { it.join() }
+        // If the test failed, crash with line number
+        crash?.let { throw it }
+    }
+
+    // Helper to get the stack trace for a calling method
+    private fun getCallingStackTrace(): Array<StackTraceElement> {
+        try {
+            throw RuntimeException()
+        } catch (e: RuntimeException) {
+            return e.stackTrace
+        }
+    }
+
+    // Find the calling method. This is the first method in the stack trace that is annotated
+    // with @Test.
+    fun getCallingMethod(): StackTraceElement {
+        val stackTrace = getCallingStackTrace()
+        return stackTrace.find { element ->
+            val clazz = Class.forName(element.className)
+            // Because the stack trace doesn't list the formal arguments, find all methods with
+            // this name and return this name if any of them is annotated with @Test.
+            clazz.declaredMethods
+                    .filter { method -> method.name == element.methodName }
+                    .any { method -> method.getAnnotation(org.junit.Test::class.java) != null }
+        } ?: stackTrace[3]
+        // If no method is annotated return the 4th one, because that's what it usually is :
+        // 0 is getCallingStackTrace, 1 is this method, 2 is ConcurrentInterpreter#interpretTestSpec
+    }
+}
+
+private fun <T> getDefaultInstructions() = listOf<InterpretMatcher<T>>(
+    // Interpret an empty line as doing nothing.
+    Regex("") to { _, _, _ -> null },
+    // Ignore comments.
+    Regex("(.*)//.*") to { i, t, r -> i.interpret(r.strArg(1), t) },
+    // Interpret "XXX time x..y" : run XXX and check it took at least x and not more than y
+    Regex("""(.*)\s*time\s*(\d+)\.\.(\d+)""") to { i, t, r ->
+        val time = measureTimeMillis { i.interpret(r.strArg(1), t) }
+        assertTrue(time in r.timeArg(2)..r.timeArg(3), "$time not in ${r.timeArg(2)..r.timeArg(3)}")
+    },
+    // Interpret "XXX = YYY" : run XXX and assert its return value is equal to YYY. "null" supported
+    Regex("""(.*)\s*=\s*(null|\d+)""") to { i, t, r ->
+        i.interpret(r.strArg(1), t).also {
+            if ("null" == r.strArg(2)) assertNull(it) else assertEquals(r.intArg(2), it)
+        }
+    },
+    // Interpret sleep. Optional argument for the count, in INTERPRET_TIME_UNIT units.
+    Regex("""sleep(\((\d+)\))?""") to { i, t, r ->
+        SystemClock.sleep(if (r.strArg(2).isEmpty()) i.interpretTimeUnit else r.timeArg(2))
+    },
+    Regex("""(.*)\s*fails""") to { i, t, r ->
+        assertFails { i.interpret(r.strArg(1), t) }
+    }
+)
+
+class SyntaxException(msg: String, cause: Throwable? = null) : RuntimeException(msg, cause)
+class InterpretException(
+    threadIndex: Int,
+    instr: String,
+    lineNum: Int,
+    className: String,
+    methodName: String,
+    fileName: String,
+    cause: Throwable
+) : RuntimeException("Failure: $instr", cause) {
+    init {
+        stackTrace = arrayOf(StackTraceElement(
+                className,
+                "$methodName:thread$threadIndex",
+                fileName,
+                lineNum)) + super.getStackTrace()
+    }
+}
+
+// Some small helpers to avoid to say the large ".groupValues[index].trim()" every time
+fun MatchResult.strArg(index: Int) = this.groupValues[index].trim()
+fun MatchResult.intArg(index: Int) = strArg(index).toInt()
+fun MatchResult.timeArg(index: Int) = INTERPRET_TIME_UNIT * intArg(index)
diff --git a/staticlibs/devicetests/com/android/testutils/DevSdkIgnoreRule.kt b/staticlibs/devicetests/com/android/testutils/DevSdkIgnoreRule.kt
new file mode 100644
index 0000000..4a83f6f
--- /dev/null
+++ b/staticlibs/devicetests/com/android/testutils/DevSdkIgnoreRule.kt
@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2020 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.testutils
+
+import android.os.Build
+import org.junit.Assume.assumeTrue
+import org.junit.rules.TestRule
+import org.junit.runner.Description
+import org.junit.runners.model.Statement
+
+/**
+ * Returns true if the development SDK version of the device is in the provided range.
+ *
+ * If the device is not using a release SDK, the development SDK is considered to be higher than
+ * [Build.VERSION.SDK_INT].
+ */
+fun isDevSdkInRange(minExclusive: Int?, maxInclusive: Int?): Boolean {
+    // In-development API n+1 will have SDK_INT == n and CODENAME != REL.
+    // Stable API n has SDK_INT == n and CODENAME == REL.
+    val release = "REL" == Build.VERSION.CODENAME
+    val sdkInt = Build.VERSION.SDK_INT
+    val devApiLevel = sdkInt + if (release) 0 else 1
+
+    return (minExclusive == null || devApiLevel > minExclusive) &&
+            (maxInclusive == null || devApiLevel <= maxInclusive)
+}
+
+/**
+ * A test rule to ignore tests based on the development SDK level.
+ *
+ * If the device is not using a release SDK, the development SDK is considered to be higher than
+ * [Build.VERSION.SDK_INT].
+ *
+ * @param ignoreClassUpTo Skip all tests in the class if the device dev SDK is <= this value.
+ * @param ignoreClassAfter Skip all tests in the class if the device dev SDK is > this value.
+ */
+class DevSdkIgnoreRule @JvmOverloads constructor(
+    private val ignoreClassUpTo: Int? = null,
+    private val ignoreClassAfter: Int? = null
+) : TestRule {
+    override fun apply(base: Statement, description: Description): Statement {
+        return IgnoreBySdkStatement(base, description)
+    }
+
+    /**
+     * Ignore the test for any development SDK that is strictly after [value].
+     *
+     * If the device is not using a release SDK, the development SDK is considered to be higher
+     * than [Build.VERSION.SDK_INT].
+     */
+    annotation class IgnoreAfter(val value: Int)
+
+    /**
+     * Ignore the test for any development SDK that lower than or equal to [value].
+     *
+     * If the device is not using a release SDK, the development SDK is considered to be higher
+     * than [Build.VERSION.SDK_INT].
+     */
+    annotation class IgnoreUpTo(val value: Int)
+
+    private inner class IgnoreBySdkStatement(
+        private val base: Statement,
+        private val description: Description
+    ) : Statement() {
+        override fun evaluate() {
+            val ignoreAfter = description.getAnnotation(IgnoreAfter::class.java)
+            val ignoreUpTo = description.getAnnotation(IgnoreUpTo::class.java)
+
+            val message = "Skipping test for build ${Build.VERSION.CODENAME} " +
+                    "with SDK ${Build.VERSION.SDK_INT}"
+            assumeTrue(message, isDevSdkInRange(ignoreClassUpTo, ignoreClassAfter))
+            assumeTrue(message, isDevSdkInRange(ignoreUpTo?.value, ignoreAfter?.value))
+            base.evaluate()
+        }
+    }
+}
\ No newline at end of file
diff --git a/staticlibs/devicetests/com/android/testutils/DevSdkIgnoreRunner.kt b/staticlibs/devicetests/com/android/testutils/DevSdkIgnoreRunner.kt
new file mode 100644
index 0000000..73b2843
--- /dev/null
+++ b/staticlibs/devicetests/com/android/testutils/DevSdkIgnoreRunner.kt
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2020 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.testutils
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.android.testutils.DevSdkIgnoreRule.IgnoreAfter
+import com.android.testutils.DevSdkIgnoreRule.IgnoreUpTo
+import org.junit.runner.Description
+import org.junit.runner.Runner
+import org.junit.runner.notification.RunNotifier
+
+/**
+ * A runner that can skip tests based on the development SDK as defined in [DevSdkIgnoreRule].
+ *
+ * Generally [DevSdkIgnoreRule] should be used for that purpose (using rules is preferable over
+ * replacing the test runner), however JUnit runners inspect all methods in the test class before
+ * processing test rules. This may cause issues if the test methods are referencing classes that do
+ * not exist on the SDK of the device the test is run on.
+ *
+ * This runner inspects [IgnoreAfter] and [IgnoreUpTo] annotations on the test class, and will skip
+ * the whole class if they do not match the development SDK as defined in [DevSdkIgnoreRule].
+ * Otherwise, it will delegate to [AndroidJUnit4] to run the test as usual.
+ *
+ * Example usage:
+ *
+ *     @RunWith(DevSdkIgnoreRunner::class)
+ *     @IgnoreUpTo(Build.VERSION_CODES.Q)
+ *     class MyTestClass { ... }
+ */
+class DevSdkIgnoreRunner(private val klass: Class<*>) : Runner() {
+    private val baseRunner = klass.let {
+        val ignoreAfter = it.getAnnotation(IgnoreAfter::class.java)
+        val ignoreUpTo = it.getAnnotation(IgnoreUpTo::class.java)
+
+        if (isDevSdkInRange(ignoreUpTo?.value, ignoreAfter?.value)) AndroidJUnit4(klass) else null
+    }
+
+    override fun run(notifier: RunNotifier) {
+        if (baseRunner != null) {
+            baseRunner.run(notifier)
+            return
+        }
+
+        // Report a single, skipped placeholder test for this class, so that the class is still
+        // visible as skipped in test results.
+        notifier.fireTestIgnored(
+                Description.createTestDescription(klass, "skippedClassForDevSdkMismatch"))
+    }
+
+    override fun getDescription(): Description {
+        return baseRunner?.description ?: Description.createSuiteDescription(klass)
+    }
+
+    override fun testCount(): Int {
+        // When ignoring the tests, a skipped placeholder test is reported, so test count is 1.
+        return baseRunner?.testCount() ?: 1
+    }
+}
\ No newline at end of file
diff --git a/staticlibs/devicetests/com/android/testutils/FakeDns.kt b/staticlibs/devicetests/com/android/testutils/FakeDns.kt
new file mode 100644
index 0000000..825d748
--- /dev/null
+++ b/staticlibs/devicetests/com/android/testutils/FakeDns.kt
@@ -0,0 +1,94 @@
+/*
+ * 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 com.android.testutils
+
+import android.net.DnsResolver
+import android.net.InetAddresses
+import android.os.Looper
+import android.os.Handler
+import com.android.internal.annotations.GuardedBy
+import java.net.InetAddress
+import java.util.concurrent.Executor
+import org.mockito.invocation.InvocationOnMock
+import org.mockito.Mockito.any
+import org.mockito.Mockito.anyInt
+import org.mockito.Mockito.doAnswer
+
+const val TYPE_UNSPECIFIED = -1
+// TODO: Integrate with NetworkMonitorTest.
+class FakeDns(val mockResolver: DnsResolver) {
+    class DnsEntry(val hostname: String, val type: Int, val addresses: List<InetAddress>) {
+        fun match(host: String, type: Int) = hostname.equals(host) && type == type
+    }
+
+    @GuardedBy("answers")
+    val answers = ArrayList<DnsEntry>()
+
+    fun getAnswer(hostname: String, type: Int): DnsEntry? = synchronized(answers) {
+        return answers.firstOrNull { it.match(hostname, type) }
+    }
+
+    fun setAnswer(hostname: String, answer: Array<String>, type: Int) = synchronized(answers) {
+        val ans = DnsEntry(hostname, type, generateAnswer(answer))
+        // Replace or remove the existing one.
+        when (val index = answers.indexOfFirst { it.match(hostname, type) }) {
+            -1 -> answers.add(ans)
+            else -> answers[index] = ans
+        }
+    }
+
+    private fun generateAnswer(answer: Array<String>) =
+            answer.filterNotNull().map { InetAddresses.parseNumericAddress(it) }
+
+    fun startMocking() {
+        // Mock DnsResolver.query() w/o type
+        doAnswer {
+            mockAnswer(it, 1, -1, 3, 5)
+        }.`when`(mockResolver).query(any() /* network */, any() /* domain */, anyInt() /* flags */,
+                any() /* executor */, any() /* cancellationSignal */, any() /*callback*/)
+        // Mock DnsResolver.query() w/ type
+        doAnswer {
+            mockAnswer(it, 1, 2, 4, 6)
+        }.`when`(mockResolver).query(any() /* network */, any() /* domain */, anyInt() /* nsType */,
+                anyInt() /* flags */, any() /* executor */, any() /* cancellationSignal */,
+        any() /*callback*/)
+    }
+
+    private fun mockAnswer(
+        it: InvocationOnMock,
+        posHos: Int,
+        posType: Int,
+        posExecutor: Int,
+        posCallback: Int
+    ) {
+        val hostname = it.arguments[posHos] as String
+        val executor = it.arguments[posExecutor] as Executor
+        val callback = it.arguments[posCallback] as DnsResolver.Callback<List<InetAddress>>
+        var type = if (posType != -1) it.arguments[posType] as Int else TYPE_UNSPECIFIED
+        val answer = getAnswer(hostname, type)
+
+        if (!answer?.addresses.isNullOrEmpty()) {
+            Handler(Looper.getMainLooper()).post({ executor.execute({
+                    callback.onAnswer(answer?.addresses, 0); }) })
+        }
+    }
+
+    /** Clears all entries. */
+    fun clearAll() = synchronized(answers) {
+        answers.clear()
+    }
+}
diff --git a/staticlibs/devicetests/com/android/testutils/HandlerUtils.kt b/staticlibs/devicetests/com/android/testutils/HandlerUtils.kt
new file mode 100644
index 0000000..fa36209
--- /dev/null
+++ b/staticlibs/devicetests/com/android/testutils/HandlerUtils.kt
@@ -0,0 +1,49 @@
+/*
+ * 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 com.android.testutils
+
+import android.os.ConditionVariable
+import android.os.Handler
+import android.os.HandlerThread
+import java.util.concurrent.Executor
+import kotlin.system.measureTimeMillis
+import kotlin.test.fail
+
+/**
+ * Block until the specified Handler or HandlerThread becomes idle, or until timeoutMs has passed.
+ */
+fun HandlerThread.waitForIdle(timeoutMs: Int) = threadHandler.waitForIdle(timeoutMs.toLong())
+fun HandlerThread.waitForIdle(timeoutMs: Long) = threadHandler.waitForIdle(timeoutMs)
+fun Handler.waitForIdle(timeoutMs: Int) = waitForIdle(timeoutMs.toLong())
+fun Handler.waitForIdle(timeoutMs: Long) {
+    val cv = ConditionVariable(false)
+    post(cv::open)
+    if (!cv.block(timeoutMs)) {
+        fail("Handler did not become idle after ${timeoutMs}ms")
+    }
+}
+
+/**
+ * Block until the given Serial Executor becomes idle, or until timeoutMs has passed.
+ */
+fun waitForIdleSerialExecutor(executor: Executor, timeoutMs: Long) {
+    val cv = ConditionVariable()
+    executor.execute(cv::open)
+    if (!cv.block(timeoutMs)) {
+        fail("Executor did not become idle after ${timeoutMs}ms")
+    }
+}
diff --git a/staticlibs/devicetests/com/android/testutils/NetworkStatsUtils.kt b/staticlibs/devicetests/com/android/testutils/NetworkStatsUtils.kt
new file mode 100644
index 0000000..8324b25
--- /dev/null
+++ b/staticlibs/devicetests/com/android/testutils/NetworkStatsUtils.kt
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2020 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.testutils
+
+import android.net.NetworkStats
+import kotlin.test.assertTrue
+
+@JvmOverloads
+fun orderInsensitiveEquals(
+    leftStats: NetworkStats,
+    rightStats: NetworkStats,
+    compareTime: Boolean = false
+): Boolean {
+    if (leftStats == rightStats) return true
+    if (compareTime && leftStats.getElapsedRealtime() != rightStats.getElapsedRealtime()) {
+        return false
+    }
+
+    // While operations such as add/subtract will preserve empty entries. This will make
+    // the result be hard to verify during test. Remove them before comparing since they
+    // are not really affect correctness.
+    // TODO (b/152827872): Remove empty entries after addition/subtraction.
+    val leftTrimmedEmpty = leftStats.removeEmptyEntries()
+    val rightTrimmedEmpty = rightStats.removeEmptyEntries()
+
+    if (leftTrimmedEmpty.size() != rightTrimmedEmpty.size()) return false
+    val left = NetworkStats.Entry()
+    val right = NetworkStats.Entry()
+    // Order insensitive compare.
+    for (i in 0 until leftTrimmedEmpty.size()) {
+        leftTrimmedEmpty.getValues(i, left)
+        val j: Int = rightTrimmedEmpty.findIndexHinted(left.iface, left.uid, left.set, left.tag,
+                left.metered, left.roaming, left.defaultNetwork, i)
+        if (j == -1) return false
+        rightTrimmedEmpty.getValues(j, right)
+        if (left != right) return false
+    }
+    return true
+}
+
+/**
+ * Assert that two {@link NetworkStats} are equals, assuming the order of the records are not
+ * necessarily the same.
+ *
+ * @note {@code elapsedRealtime} is not compared by default, given that in test cases that is not
+ *       usually used.
+ */
+@JvmOverloads
+fun assertNetworkStatsEquals(
+    expected: NetworkStats,
+    actual: NetworkStats,
+    compareTime: Boolean = false
+) {
+    assertTrue(orderInsensitiveEquals(expected, actual, compareTime),
+            "expected: " + expected + " but was: " + actual)
+}
+
+/**
+ * Assert that after being parceled then unparceled, {@link NetworkStats} is equal to the original
+ * object.
+ */
+fun assertParcelingIsLossless(stats: NetworkStats) {
+    assertParcelingIsLossless(stats, { a, b -> orderInsensitiveEquals(a, b) })
+}
diff --git a/staticlibs/devicetests/com/android/testutils/ParcelUtils.kt b/staticlibs/devicetests/com/android/testutils/ParcelUtils.kt
new file mode 100644
index 0000000..5784f7c
--- /dev/null
+++ b/staticlibs/devicetests/com/android/testutils/ParcelUtils.kt
@@ -0,0 +1,68 @@
+/*
+ * 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 com.android.testutils
+
+import android.os.Parcel
+import android.os.Parcelable
+import kotlin.test.assertTrue
+import kotlin.test.fail
+
+/**
+ * Return a new instance of `T` after being parceled then unparceled.
+ */
+fun <T : Parcelable> parcelingRoundTrip(source: T): T {
+    val creator: Parcelable.Creator<T>
+    try {
+        creator = source.javaClass.getField("CREATOR").get(null) as Parcelable.Creator<T>
+    } catch (e: IllegalAccessException) {
+        fail("Missing CREATOR field: " + e.message)
+    } catch (e: NoSuchFieldException) {
+        fail("Missing CREATOR field: " + e.message)
+    }
+
+    var p = Parcel.obtain()
+    source.writeToParcel(p, /* flags */ 0)
+    p.setDataPosition(0)
+    val marshalled = p.marshall()
+    p = Parcel.obtain()
+    p.unmarshall(marshalled, 0, marshalled.size)
+    p.setDataPosition(0)
+    return creator.createFromParcel(p)
+}
+
+/**
+ * Assert that after being parceled then unparceled, `source` is equal to the original
+ * object. If a customized equals function is provided, uses the provided one.
+ */
+@JvmOverloads
+fun <T : Parcelable> assertParcelingIsLossless(
+    source: T,
+    equals: (T, T) -> Boolean = { a, b -> a == b }
+) {
+    val actual = parcelingRoundTrip(source)
+    assertTrue(equals(source, actual), "Expected $source, but was $actual")
+}
+
+@JvmOverloads
+fun <T : Parcelable> assertParcelSane(
+    obj: T,
+    fieldCount: Int,
+    equals: (T, T) -> Boolean = { a, b -> a == b }
+) {
+    assertFieldCountEquals(fieldCount, obj::class.java)
+    assertParcelingIsLossless(obj, equals)
+}
diff --git a/staticlibs/devicetests/com/android/testutils/TapPacketReader.java b/staticlibs/devicetests/com/android/testutils/TapPacketReader.java
new file mode 100644
index 0000000..fea1cd9
--- /dev/null
+++ b/staticlibs/devicetests/com/android/testutils/TapPacketReader.java
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2020 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.testutils;
+
+import android.net.util.PacketReader;
+import android.os.Handler;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.android.net.module.util.ArrayTrackRecord;
+
+import java.io.FileDescriptor;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.function.Predicate;
+
+import kotlin.Lazy;
+import kotlin.LazyKt;
+
+public class TapPacketReader extends PacketReader {
+    private final FileDescriptor mTapFd;
+    private final ArrayTrackRecord<byte[]> mReceivedPackets = new ArrayTrackRecord<>();
+    private final Lazy<ArrayTrackRecord<byte[]>.ReadHead> mReadHead =
+            LazyKt.lazy(mReceivedPackets::newReadHead);
+
+    public TapPacketReader(Handler h, FileDescriptor tapFd, int maxPacketSize) {
+        super(h, maxPacketSize);
+        mTapFd = tapFd;
+    }
+
+    @Override
+    protected FileDescriptor createFd() {
+        return mTapFd;
+    }
+
+    @Override
+    protected void handlePacket(byte[] recvbuf, int length) {
+        final byte[] newPacket = Arrays.copyOf(recvbuf, length);
+        if (!mReceivedPackets.add(newPacket)) {
+            throw new AssertionError("More than " + Integer.MAX_VALUE + " packets outstanding!");
+        }
+    }
+
+    /**
+     * Get the next packet that was received on the interface.
+     */
+    @Nullable
+    public byte[] popPacket(long timeoutMs) {
+        return mReadHead.getValue().poll(timeoutMs, packet -> true);
+    }
+
+    /**
+     * Get the next packet that was received on the interface and matches the specified filter.
+     */
+    @Nullable
+    public byte[] popPacket(long timeoutMs, @NonNull Predicate<byte[]> filter) {
+        return mReadHead.getValue().poll(timeoutMs, filter::test);
+    }
+
+    /**
+     * Get the {@link ArrayTrackRecord} that records all packets received by the reader since its
+     * creation.
+     */
+    public ArrayTrackRecord<byte[]> getReceivedPackets() {
+        return mReceivedPackets;
+    }
+
+    public void sendResponse(final ByteBuffer packet) throws IOException {
+        try (FileOutputStream out = new FileOutputStream(mTapFd)) {
+            byte[] packetBytes = new byte[packet.limit()];
+            packet.get(packetBytes);
+            packet.flip();  // So we can reuse it in the future.
+            out.write(packetBytes);
+        }
+    }
+}
diff --git a/staticlibs/devicetests/com/android/testutils/TestNetworkTracker.kt b/staticlibs/devicetests/com/android/testutils/TestNetworkTracker.kt
new file mode 100644
index 0000000..4bd9ae8
--- /dev/null
+++ b/staticlibs/devicetests/com/android/testutils/TestNetworkTracker.kt
@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2020 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.testutils
+
+import android.content.Context
+import android.net.ConnectivityManager
+import android.net.ConnectivityManager.NetworkCallback
+import android.net.LinkAddress
+import android.net.Network
+import android.net.NetworkCapabilities
+import android.net.NetworkRequest
+import android.net.StringNetworkSpecifier
+import android.net.TestNetworkInterface
+import android.net.TestNetworkManager
+import android.os.Binder
+import java.util.concurrent.CompletableFuture
+import java.util.concurrent.TimeUnit
+
+/**
+ * Create a test network based on a TUN interface.
+ *
+ * This method will block until the test network is available. Requires
+ * [android.Manifest.permission.CHANGE_NETWORK_STATE] and
+ * [android.Manifest.permission.MANAGE_TEST_NETWORKS].
+ */
+fun initTestNetwork(context: Context, interfaceAddr: LinkAddress, setupTimeoutMs: Long = 10_000L):
+        TestNetworkTracker {
+    val tnm = context.getSystemService(TestNetworkManager::class.java)
+    val iface = tnm.createTunInterface(arrayOf(interfaceAddr))
+    return TestNetworkTracker(context, iface, tnm, setupTimeoutMs)
+}
+
+/**
+ * Utility class to create and track test networks.
+ *
+ * This class is not thread-safe.
+ */
+class TestNetworkTracker internal constructor(
+    val context: Context,
+    val iface: TestNetworkInterface,
+    tnm: TestNetworkManager,
+    setupTimeoutMs: Long
+) {
+    private val cm = context.getSystemService(ConnectivityManager::class.java)
+    private val binder = Binder()
+
+    private val networkCallback: NetworkCallback
+    val network: Network
+
+    init {
+        val networkFuture = CompletableFuture<Network>()
+        val networkRequest = NetworkRequest.Builder()
+                .addTransportType(NetworkCapabilities.TRANSPORT_TEST)
+                // Test networks do not have NOT_VPN or TRUSTED capabilities by default
+                .removeCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN)
+                .removeCapability(NetworkCapabilities.NET_CAPABILITY_TRUSTED)
+                .setNetworkSpecifier(StringNetworkSpecifier(iface.interfaceName))
+                .build()
+        networkCallback = object : NetworkCallback() {
+            override fun onAvailable(network: Network) {
+                networkFuture.complete(network)
+            }
+        }
+        cm.requestNetwork(networkRequest, networkCallback)
+
+        try {
+            tnm.setupTestNetwork(iface.interfaceName, binder)
+            network = networkFuture.get(setupTimeoutMs, TimeUnit.MILLISECONDS)
+        } catch (e: Throwable) {
+            teardown()
+            throw e
+        }
+    }
+
+    fun teardown() {
+        cm.unregisterNetworkCallback(networkCallback)
+    }
+}
\ No newline at end of file
diff --git a/staticlibs/devicetests/com/android/testutils/TestableNetworkCallback.kt b/staticlibs/devicetests/com/android/testutils/TestableNetworkCallback.kt
new file mode 100644
index 0000000..959a837
--- /dev/null
+++ b/staticlibs/devicetests/com/android/testutils/TestableNetworkCallback.kt
@@ -0,0 +1,393 @@
+/*
+ * 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 com.android.testutils
+
+import android.net.ConnectivityManager.NetworkCallback
+import android.net.LinkProperties
+import android.net.Network
+import android.net.NetworkCapabilities
+import android.net.NetworkCapabilities.NET_CAPABILITY_VALIDATED
+import com.android.net.module.util.ArrayTrackRecord
+import com.android.testutils.RecorderCallback.CallbackEntry.Available
+import com.android.testutils.RecorderCallback.CallbackEntry.BlockedStatus
+import com.android.testutils.RecorderCallback.CallbackEntry.CapabilitiesChanged
+import com.android.testutils.RecorderCallback.CallbackEntry.LinkPropertiesChanged
+import com.android.testutils.RecorderCallback.CallbackEntry.Losing
+import com.android.testutils.RecorderCallback.CallbackEntry.Lost
+import com.android.testutils.RecorderCallback.CallbackEntry.Resumed
+import com.android.testutils.RecorderCallback.CallbackEntry.Suspended
+import com.android.testutils.RecorderCallback.CallbackEntry.Unavailable
+import kotlin.reflect.KClass
+import kotlin.test.assertEquals
+import kotlin.test.assertNotNull
+import kotlin.test.assertTrue
+import kotlin.test.fail
+
+object NULL_NETWORK : Network(-1)
+object ANY_NETWORK : Network(-2)
+
+private val Int.capabilityName get() = NetworkCapabilities.capabilityNameOf(this)
+
+open class RecorderCallback private constructor(
+    private val backingRecord: ArrayTrackRecord<CallbackEntry>
+) : NetworkCallback() {
+    public constructor() : this(ArrayTrackRecord())
+    protected constructor(src: RecorderCallback?): this(src?.backingRecord ?: ArrayTrackRecord())
+
+    sealed class CallbackEntry {
+        // To get equals(), hashcode(), componentN() etc for free, the child classes of
+        // this class are data classes. But while data classes can inherit from other classes,
+        // they may only have visible members in the constructors, so they couldn't declare
+        // a constructor with a non-val arg to pass to CallbackEntry. Instead, force all
+        // subclasses to implement a `network' property, which can be done in a data class
+        // constructor by specifying override.
+        abstract val network: Network
+
+        data class Available(override val network: Network) : CallbackEntry()
+        data class CapabilitiesChanged(
+            override val network: Network,
+            val caps: NetworkCapabilities
+        ) : CallbackEntry()
+        data class LinkPropertiesChanged(
+            override val network: Network,
+            val lp: LinkProperties
+        ) : CallbackEntry()
+        data class Suspended(override val network: Network) : CallbackEntry()
+        data class Resumed(override val network: Network) : CallbackEntry()
+        data class Losing(override val network: Network, val maxMsToLive: Int) : CallbackEntry()
+        data class Lost(override val network: Network) : CallbackEntry()
+        data class Unavailable private constructor(
+            override val network: Network
+        ) : CallbackEntry() {
+            constructor() : this(NULL_NETWORK)
+        }
+        data class BlockedStatus(
+            override val network: Network,
+            val blocked: Boolean
+        ) : CallbackEntry()
+
+        // Convenience constants for expecting a type
+        companion object {
+            @JvmField
+            val AVAILABLE = Available::class
+            @JvmField
+            val NETWORK_CAPS_UPDATED = CapabilitiesChanged::class
+            @JvmField
+            val LINK_PROPERTIES_CHANGED = LinkPropertiesChanged::class
+            @JvmField
+            val SUSPENDED = Suspended::class
+            @JvmField
+            val RESUMED = Resumed::class
+            @JvmField
+            val LOSING = Losing::class
+            @JvmField
+            val LOST = Lost::class
+            @JvmField
+            val UNAVAILABLE = Unavailable::class
+            @JvmField
+            val BLOCKED_STATUS = BlockedStatus::class
+        }
+    }
+
+    val history = backingRecord.newReadHead()
+    val mark get() = history.mark
+
+    override fun onAvailable(network: Network) {
+        history.add(Available(network))
+    }
+
+    // PreCheck is not used in the tests today. For backward compatibility with existing tests that
+    // expect the callbacks not to record this, do not listen to PreCheck here.
+
+    override fun onCapabilitiesChanged(network: Network, caps: NetworkCapabilities) {
+        history.add(CapabilitiesChanged(network, caps))
+    }
+
+    override fun onLinkPropertiesChanged(network: Network, lp: LinkProperties) {
+        history.add(LinkPropertiesChanged(network, lp))
+    }
+
+    override fun onBlockedStatusChanged(network: Network, blocked: Boolean) {
+        history.add(BlockedStatus(network, blocked))
+    }
+
+    override fun onNetworkSuspended(network: Network) {
+        history.add(Suspended(network))
+    }
+
+    override fun onNetworkResumed(network: Network) {
+        history.add(Resumed(network))
+    }
+
+    override fun onLosing(network: Network, maxMsToLive: Int) {
+        history.add(Losing(network, maxMsToLive))
+    }
+
+    override fun onLost(network: Network) {
+        history.add(Lost(network))
+    }
+
+    override fun onUnavailable() {
+        history.add(Unavailable())
+    }
+}
+
+private const val DEFAULT_TIMEOUT = 200L // ms
+
+open class TestableNetworkCallback private constructor(
+    src: TestableNetworkCallback?,
+    val defaultTimeoutMs: Long = DEFAULT_TIMEOUT
+) : RecorderCallback(src) {
+    @JvmOverloads
+    constructor(timeoutMs: Long = DEFAULT_TIMEOUT): this(null, timeoutMs)
+
+    fun createLinkedCopy() = TestableNetworkCallback(this, defaultTimeoutMs)
+
+    // The last available network, or null if any network was lost since the last call to
+    // onAvailable. TODO : fix this by fixing the tests that rely on this behavior
+    val lastAvailableNetwork: Network?
+        get() = when (val it = history.lastOrNull { it is Available || it is Lost }) {
+            is Available -> it.network
+            else -> null
+        }
+
+    fun pollForNextCallback(timeoutMs: Long = defaultTimeoutMs): CallbackEntry {
+        return history.poll(timeoutMs) ?: fail("Did not receive callback after ${timeoutMs}ms")
+    }
+
+    // Make open for use in ConnectivityServiceTest which is the only one knowing its handlers.
+    @JvmOverloads
+    open fun assertNoCallback(timeoutMs: Long = defaultTimeoutMs) {
+        val cb = history.poll(timeoutMs)
+        if (null != cb) fail("Expected no callback but got $cb")
+    }
+
+    // Expects a callback of the specified type on the specified network within the timeout.
+    // If no callback arrives, or a different callback arrives, fail. Returns the callback.
+    inline fun <reified T : CallbackEntry> expectCallback(
+        network: Network = ANY_NETWORK,
+        timeoutMs: Long = defaultTimeoutMs
+    ): T = pollForNextCallback(timeoutMs).let {
+        if (it !is T || (ANY_NETWORK !== network && it.network != network)) {
+            fail("Unexpected callback : $it, expected ${T::class} with Network[$network]")
+        } else {
+            it
+        }
+    }
+
+    // Expects a callback of the specified type matching the predicate within the timeout.
+    // Any callback that doesn't match the predicate will be skipped. Fails only if
+    // no matching callback is received within the timeout.
+    inline fun <reified T : CallbackEntry> eventuallyExpect(
+        timeoutMs: Long = defaultTimeoutMs,
+        from: Int = mark,
+        crossinline predicate: (T) -> Boolean = { true }
+    ): T = eventuallyExpectOrNull(timeoutMs, from, predicate).also {
+        assertNotNull(it, "Callback ${T::class} not received within ${timeoutMs}ms")
+    } as T
+
+    // TODO (b/157405399) straighten and unify the method names
+    inline fun <reified T : CallbackEntry> eventuallyExpectOrNull(
+        timeoutMs: Long = defaultTimeoutMs,
+        from: Int = mark,
+        crossinline predicate: (T) -> Boolean = { true }
+    ) = history.poll(timeoutMs, from) { it is T && predicate(it) } as T?
+
+    fun expectCallbackThat(
+        timeoutMs: Long = defaultTimeoutMs,
+        valid: (CallbackEntry) -> Boolean
+    ) = pollForNextCallback(timeoutMs).also { assertTrue(valid(it), "Unexpected callback : $it") }
+
+    fun expectCapabilitiesThat(
+        net: Network,
+        tmt: Long = defaultTimeoutMs,
+        valid: (NetworkCapabilities) -> Boolean
+    ): CapabilitiesChanged {
+        return expectCallback<CapabilitiesChanged>(net, tmt).also {
+            assertTrue(valid(it.caps), "Capabilities don't match expectations ${it.caps}")
+        }
+    }
+
+    fun expectLinkPropertiesThat(
+        net: Network,
+        tmt: Long = defaultTimeoutMs,
+        valid: (LinkProperties) -> Boolean
+    ): LinkPropertiesChanged {
+        return expectCallback<LinkPropertiesChanged>(net, tmt).also {
+            assertTrue(valid(it.lp), "LinkProperties don't match expectations ${it.lp}")
+        }
+    }
+
+    // Expects onAvailable and the callbacks that follow it. These are:
+    // - onSuspended, iff the network was suspended when the callbacks fire.
+    // - onCapabilitiesChanged.
+    // - onLinkPropertiesChanged.
+    // - onBlockedStatusChanged.
+    //
+    // @param network the network to expect the callbacks on.
+    // @param suspended whether to expect a SUSPENDED callback.
+    // @param validated the expected value of the VALIDATED capability in the
+    //        onCapabilitiesChanged callback.
+    // @param tmt how long to wait for the callbacks.
+    fun expectAvailableCallbacks(
+        net: Network,
+        suspended: Boolean = false,
+        validated: Boolean = true,
+        blocked: Boolean = false,
+        tmt: Long = defaultTimeoutMs
+    ) {
+        expectCallback<Available>(net, tmt)
+        if (suspended) {
+            expectCallback<Suspended>(net, tmt)
+        }
+        expectCapabilitiesThat(net, tmt) { validated == it.hasCapability(NET_CAPABILITY_VALIDATED) }
+        expectCallback<LinkPropertiesChanged>(net, tmt)
+        expectBlockedStatusCallback(blocked, net)
+    }
+
+    // Backward compatibility for existing Java code. Use named arguments instead and remove all
+    // these when there is no user left.
+    fun expectAvailableAndSuspendedCallbacks(
+        net: Network,
+        validated: Boolean,
+        tmt: Long = defaultTimeoutMs
+    ) = expectAvailableCallbacks(net, suspended = true, validated = validated, tmt = tmt)
+
+    fun expectBlockedStatusCallback(blocked: Boolean, net: Network, tmt: Long = defaultTimeoutMs) {
+        expectCallback<BlockedStatus>(net, tmt).also {
+            assertEquals(it.blocked, blocked, "Unexpected blocked status ${it.blocked}")
+        }
+    }
+
+    // Expects the available callbacks (where the onCapabilitiesChanged must contain the
+    // VALIDATED capability), plus another onCapabilitiesChanged which is identical to the
+    // one we just sent.
+    // TODO: this is likely a bug. Fix it and remove this method.
+    fun expectAvailableDoubleValidatedCallbacks(net: Network, tmt: Long = defaultTimeoutMs) {
+        val mark = history.mark
+        expectAvailableCallbacks(net, tmt = tmt)
+        val firstCaps = history.poll(tmt, mark) { it is CapabilitiesChanged }
+        assertEquals(firstCaps, expectCallback<CapabilitiesChanged>(net, tmt))
+    }
+
+    // Expects the available callbacks where the onCapabilitiesChanged must not have validated,
+    // then expects another onCapabilitiesChanged that has the validated bit set. This is used
+    // when a network connects and satisfies a callback, and then immediately validates.
+    fun expectAvailableThenValidatedCallbacks(net: Network, tmt: Long = defaultTimeoutMs) {
+        expectAvailableCallbacks(net, validated = false, tmt = tmt)
+        expectCapabilitiesThat(net, tmt) { it.hasCapability(NET_CAPABILITY_VALIDATED) }
+    }
+
+    // Temporary Java compat measure : have MockNetworkAgent implement this so that all existing
+    // calls with networkAgent can be routed through here without moving MockNetworkAgent.
+    // TODO: clean this up, remove this method.
+    interface HasNetwork {
+        val network: Network
+    }
+
+    @JvmOverloads
+    open fun <T : CallbackEntry> expectCallback(
+        type: KClass<T>,
+        n: Network?,
+        timeoutMs: Long = defaultTimeoutMs
+    ) = pollForNextCallback(timeoutMs).also {
+        val network = n ?: NULL_NETWORK
+        // TODO : remove this .java access if the tests ever use kotlin-reflect. At the time of
+        // this writing this would be the only use of this library in the tests.
+        assertTrue(type.java.isInstance(it) && it.network == network,
+                "Unexpected callback : $it, expected ${type.java} with Network[$network]")
+    } as T
+
+    @JvmOverloads
+    open fun <T : CallbackEntry> expectCallback(
+        type: KClass<T>,
+        n: HasNetwork?,
+        timeoutMs: Long = defaultTimeoutMs
+    ) = expectCallback(type, n?.network, timeoutMs)
+
+    fun expectAvailableCallbacks(
+        n: HasNetwork,
+        suspended: Boolean,
+        validated: Boolean,
+        blocked: Boolean,
+        timeoutMs: Long
+    ) = expectAvailableCallbacks(n.network, suspended, validated, blocked, timeoutMs)
+
+    fun expectAvailableAndSuspendedCallbacks(n: HasNetwork, expectValidated: Boolean) {
+        expectAvailableAndSuspendedCallbacks(n.network, expectValidated)
+    }
+
+    fun expectAvailableCallbacksValidated(n: HasNetwork) {
+        expectAvailableCallbacks(n.network)
+    }
+
+    fun expectAvailableCallbacksValidatedAndBlocked(n: HasNetwork) {
+        expectAvailableCallbacks(n.network, blocked = true)
+    }
+
+    fun expectAvailableCallbacksUnvalidated(n: HasNetwork) {
+        expectAvailableCallbacks(n.network, validated = false)
+    }
+
+    fun expectAvailableCallbacksUnvalidatedAndBlocked(n: HasNetwork) {
+        expectAvailableCallbacks(n.network, validated = false, blocked = true)
+    }
+
+    fun expectAvailableDoubleValidatedCallbacks(n: HasNetwork) {
+        expectAvailableDoubleValidatedCallbacks(n.network, defaultTimeoutMs)
+    }
+
+    fun expectAvailableThenValidatedCallbacks(n: HasNetwork) {
+        expectAvailableThenValidatedCallbacks(n.network, defaultTimeoutMs)
+    }
+
+    @JvmOverloads
+    fun expectLinkPropertiesThat(
+        n: HasNetwork,
+        tmt: Long = defaultTimeoutMs,
+        valid: (LinkProperties) -> Boolean
+    ) = expectLinkPropertiesThat(n.network, tmt, valid)
+
+    @JvmOverloads
+    fun expectCapabilitiesThat(
+        n: HasNetwork,
+        tmt: Long = defaultTimeoutMs,
+        valid: (NetworkCapabilities) -> Boolean
+    ) = expectCapabilitiesThat(n.network, tmt, valid)
+
+    @JvmOverloads
+    fun expectCapabilitiesWith(
+        capability: Int,
+        n: HasNetwork,
+        timeoutMs: Long = defaultTimeoutMs
+    ): NetworkCapabilities {
+        return expectCapabilitiesThat(n.network, timeoutMs) { it.hasCapability(capability) }.caps
+    }
+
+    @JvmOverloads
+    fun expectCapabilitiesWithout(
+        capability: Int,
+        n: HasNetwork,
+        timeoutMs: Long = defaultTimeoutMs
+    ): NetworkCapabilities {
+        return expectCapabilitiesThat(n.network, timeoutMs) { !it.hasCapability(capability) }.caps
+    }
+
+    fun expectBlockedStatusCallback(expectBlocked: Boolean, n: HasNetwork) {
+        expectBlockedStatusCallback(expectBlocked, n.network, defaultTimeoutMs)
+    }
+}
diff --git a/staticlibs/devicetests/com/android/testutils/TestableNetworkStatsProvider.kt b/staticlibs/devicetests/com/android/testutils/TestableNetworkStatsProvider.kt
new file mode 100644
index 0000000..d5c3a2a
--- /dev/null
+++ b/staticlibs/devicetests/com/android/testutils/TestableNetworkStatsProvider.kt
@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2020 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.testutils
+
+import android.net.netstats.provider.NetworkStatsProvider
+import com.android.net.module.util.ArrayTrackRecord
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+import kotlin.test.fail
+
+private const val DEFAULT_TIMEOUT_MS = 200L
+
+open class TestableNetworkStatsProvider(
+    val defaultTimeoutMs: Long = DEFAULT_TIMEOUT_MS
+) : NetworkStatsProvider() {
+    sealed class CallbackType {
+        data class OnRequestStatsUpdate(val token: Int) : CallbackType()
+        data class OnSetLimit(val iface: String?, val quotaBytes: Long) : CallbackType()
+        data class OnSetAlert(val quotaBytes: Long) : CallbackType()
+    }
+
+    val history = ArrayTrackRecord<CallbackType>().newReadHead()
+    // See ReadHead#mark
+    val mark get() = history.mark
+
+    override fun onRequestStatsUpdate(token: Int) {
+        history.add(CallbackType.OnRequestStatsUpdate(token))
+    }
+
+    override fun onSetLimit(iface: String, quotaBytes: Long) {
+        history.add(CallbackType.OnSetLimit(iface, quotaBytes))
+    }
+
+    override fun onSetAlert(quotaBytes: Long) {
+        history.add(CallbackType.OnSetAlert(quotaBytes))
+    }
+
+    fun expectOnRequestStatsUpdate(token: Int, timeout: Long = defaultTimeoutMs) {
+        assertEquals(CallbackType.OnRequestStatsUpdate(token), history.poll(timeout))
+    }
+
+    fun expectOnSetLimit(iface: String?, quotaBytes: Long, timeout: Long = defaultTimeoutMs) {
+        assertEquals(CallbackType.OnSetLimit(iface, quotaBytes), history.poll(timeout))
+    }
+
+    fun expectOnSetAlert(quotaBytes: Long, timeout: Long = defaultTimeoutMs) {
+        assertEquals(CallbackType.OnSetAlert(quotaBytes), history.poll(timeout))
+    }
+
+    fun pollForNextCallback(timeout: Long = defaultTimeoutMs) =
+        history.poll(timeout) ?: fail("Did not receive callback after ${timeout}ms")
+
+    inline fun <reified T : CallbackType> expectCallback(
+        timeout: Long = defaultTimeoutMs,
+        predicate: (T) -> Boolean = { true }
+    ): T {
+        return pollForNextCallback(timeout).also { assertTrue(it is T && predicate(it)) } as T
+    }
+
+    // Expects a callback of the specified type matching the predicate within the timeout.
+    // Any callback that doesn't match the predicate will be skipped. Fails only if
+    // no matching callback is received within the timeout.
+    // TODO : factorize the code for this with the identical call in TestableNetworkCallback.
+    // There should be a common superclass doing this generically.
+    // TODO : have a better error message to have this fail. Right now the failure when no
+    // matching callback arrives comes from the casting to a non-nullable T.
+    // TODO : in fact, completely removing this method and have clients use
+    // history.poll(timeout, index, predicate) directly might be simpler.
+    inline fun <reified T : CallbackType> eventuallyExpect(
+        timeoutMs: Long = defaultTimeoutMs,
+        from: Int = mark,
+        crossinline predicate: (T) -> Boolean = { true }
+    ) = history.poll(timeoutMs, from) { it is T && predicate(it) } as T
+
+    fun drainCallbacks() {
+        history.mark = history.size
+    }
+
+    @JvmOverloads
+    fun assertNoCallback(timeout: Long = defaultTimeoutMs) {
+        val cb = history.poll(timeout)
+        cb?.let { fail("Expected no callback but got $cb") }
+    }
+}
diff --git a/staticlibs/devicetests/com/android/testutils/TestableNetworkStatsProviderBinder.kt b/staticlibs/devicetests/com/android/testutils/TestableNetworkStatsProviderBinder.kt
new file mode 100644
index 0000000..02922d8
--- /dev/null
+++ b/staticlibs/devicetests/com/android/testutils/TestableNetworkStatsProviderBinder.kt
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2020 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.testutils
+
+import android.net.netstats.provider.INetworkStatsProvider
+import com.android.net.module.util.ArrayTrackRecord
+import kotlin.test.assertEquals
+import kotlin.test.fail
+
+private const val DEFAULT_TIMEOUT_MS = 200L
+
+open class TestableNetworkStatsProviderBinder : INetworkStatsProvider.Stub() {
+    sealed class CallbackType {
+        data class OnRequestStatsUpdate(val token: Int) : CallbackType()
+        data class OnSetLimit(val iface: String?, val quotaBytes: Long) : CallbackType()
+        data class OnSetAlert(val quotaBytes: Long) : CallbackType()
+    }
+
+    private val history = ArrayTrackRecord<CallbackType>().ReadHead()
+
+    override fun onRequestStatsUpdate(token: Int) {
+        history.add(CallbackType.OnRequestStatsUpdate(token))
+    }
+
+    override fun onSetLimit(iface: String?, quotaBytes: Long) {
+        history.add(CallbackType.OnSetLimit(iface, quotaBytes))
+    }
+
+    override fun onSetAlert(quotaBytes: Long) {
+        history.add(CallbackType.OnSetAlert(quotaBytes))
+    }
+
+    fun expectOnRequestStatsUpdate(token: Int) {
+        assertEquals(CallbackType.OnRequestStatsUpdate(token), history.poll(DEFAULT_TIMEOUT_MS))
+    }
+
+    fun expectOnSetLimit(iface: String?, quotaBytes: Long) {
+        assertEquals(CallbackType.OnSetLimit(iface, quotaBytes), history.poll(DEFAULT_TIMEOUT_MS))
+    }
+
+    fun expectOnSetAlert(quotaBytes: Long) {
+        assertEquals(CallbackType.OnSetAlert(quotaBytes), history.poll(DEFAULT_TIMEOUT_MS))
+    }
+
+    @JvmOverloads
+    fun assertNoCallback(timeout: Long = DEFAULT_TIMEOUT_MS) {
+        val cb = history.poll(timeout)
+        cb?.let { fail("Expected no callback but got $cb") }
+    }
+}
diff --git a/staticlibs/devicetests/com/android/testutils/TestableNetworkStatsProviderCbBinder.kt b/staticlibs/devicetests/com/android/testutils/TestableNetworkStatsProviderCbBinder.kt
new file mode 100644
index 0000000..163473a
--- /dev/null
+++ b/staticlibs/devicetests/com/android/testutils/TestableNetworkStatsProviderCbBinder.kt
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2020 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.testutils
+
+import android.net.NetworkStats
+import android.net.netstats.provider.INetworkStatsProviderCallback
+import com.android.net.module.util.ArrayTrackRecord
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+import kotlin.test.fail
+
+private const val DEFAULT_TIMEOUT_MS = 3000L
+
+open class TestableNetworkStatsProviderCbBinder : INetworkStatsProviderCallback.Stub() {
+    sealed class CallbackType {
+        data class NotifyStatsUpdated(
+            val token: Int,
+            val ifaceStats: NetworkStats,
+            val uidStats: NetworkStats
+        ) : CallbackType()
+        object NotifyLimitReached : CallbackType()
+        object NotifyAlertReached : CallbackType()
+        object Unregister : CallbackType()
+    }
+
+    private val history = ArrayTrackRecord<CallbackType>().ReadHead()
+
+    override fun notifyStatsUpdated(token: Int, ifaceStats: NetworkStats, uidStats: NetworkStats) {
+        history.add(CallbackType.NotifyStatsUpdated(token, ifaceStats, uidStats))
+    }
+
+    override fun notifyLimitReached() {
+        history.add(CallbackType.NotifyLimitReached)
+    }
+
+    override fun notifyAlertReached() {
+        history.add(CallbackType.NotifyAlertReached)
+    }
+
+    override fun unregister() {
+        history.add(CallbackType.Unregister)
+    }
+
+    fun expectNotifyStatsUpdated() {
+        val event = history.poll(DEFAULT_TIMEOUT_MS)
+        assertTrue(event is CallbackType.NotifyStatsUpdated)
+    }
+
+    fun expectNotifyStatsUpdated(ifaceStats: NetworkStats, uidStats: NetworkStats) {
+        val event = history.poll(DEFAULT_TIMEOUT_MS)!!
+        if (event !is CallbackType.NotifyStatsUpdated) {
+            throw Exception("Expected NotifyStatsUpdated callback, but got ${event::class}")
+        }
+        // TODO: verify token.
+        assertNetworkStatsEquals(ifaceStats, event.ifaceStats)
+        assertNetworkStatsEquals(uidStats, event.uidStats)
+    }
+
+    fun expectNotifyLimitReached() =
+            assertEquals(CallbackType.NotifyLimitReached, history.poll(DEFAULT_TIMEOUT_MS))
+
+    fun expectNotifyAlertReached() =
+            assertEquals(CallbackType.NotifyAlertReached, history.poll(DEFAULT_TIMEOUT_MS))
+
+    // Assert there is no callback in current queue.
+    fun assertNoCallback() {
+        val cb = history.poll(0)
+        cb?.let { fail("Expected no callback but got $cb") }
+    }
+}
diff --git a/staticlibs/src_frameworkcommon/android/net/util/IpRange.java b/staticlibs/framework/android/net/util/IpRange.java
similarity index 100%
rename from staticlibs/src_frameworkcommon/android/net/util/IpRange.java
rename to staticlibs/framework/android/net/util/IpRange.java
diff --git a/staticlibs/src_frameworkcommon/android/net/util/LinkPropertiesUtils.java b/staticlibs/framework/android/net/util/LinkPropertiesUtils.java
similarity index 100%
rename from staticlibs/src_frameworkcommon/android/net/util/LinkPropertiesUtils.java
rename to staticlibs/framework/android/net/util/LinkPropertiesUtils.java
diff --git a/staticlibs/src_frameworkcommon/android/net/util/MacAddressUtils.java b/staticlibs/framework/android/net/util/MacAddressUtils.java
similarity index 100%
rename from staticlibs/src_frameworkcommon/android/net/util/MacAddressUtils.java
rename to staticlibs/framework/android/net/util/MacAddressUtils.java
diff --git a/staticlibs/src_frameworkcommon/android/net/util/NetUtils.java b/staticlibs/framework/android/net/util/NetUtils.java
similarity index 100%
rename from staticlibs/src_frameworkcommon/android/net/util/NetUtils.java
rename to staticlibs/framework/android/net/util/NetUtils.java
diff --git a/staticlibs/src_frameworkcommon/android/net/util/nsd/DnsSdTxtRecord.java b/staticlibs/framework/android/net/util/nsd/DnsSdTxtRecord.java
similarity index 100%
rename from staticlibs/src_frameworkcommon/android/net/util/nsd/DnsSdTxtRecord.java
rename to staticlibs/framework/android/net/util/nsd/DnsSdTxtRecord.java
diff --git a/staticlibs/src_frameworkcommon/com/android/net/module/util/DnsPacket.java b/staticlibs/framework/com/android/net/module/util/DnsPacket.java
similarity index 100%
rename from staticlibs/src_frameworkcommon/com/android/net/module/util/DnsPacket.java
rename to staticlibs/framework/com/android/net/module/util/DnsPacket.java
diff --git a/staticlibs/src_frameworkcommon/com/android/net/module/util/Inet4AddressUtils.java b/staticlibs/framework/com/android/net/module/util/Inet4AddressUtils.java
similarity index 100%
rename from staticlibs/src_frameworkcommon/com/android/net/module/util/Inet4AddressUtils.java
rename to staticlibs/framework/com/android/net/module/util/Inet4AddressUtils.java
diff --git a/staticlibs/src_frameworkcommon/com/android/net/module/util/InetAddressUtils.java b/staticlibs/framework/com/android/net/module/util/InetAddressUtils.java
similarity index 100%
rename from staticlibs/src_frameworkcommon/com/android/net/module/util/InetAddressUtils.java
rename to staticlibs/framework/com/android/net/module/util/InetAddressUtils.java
diff --git a/staticlibs/hostdevice/com/android/net/module/util/TrackRecord.kt b/staticlibs/hostdevice/com/android/net/module/util/TrackRecord.kt
new file mode 100644
index 0000000..b647d99
--- /dev/null
+++ b/staticlibs/hostdevice/com/android/net/module/util/TrackRecord.kt
@@ -0,0 +1,247 @@
+/*
+ * 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 com.android.net.module.util
+
+import java.util.concurrent.TimeUnit
+import java.util.concurrent.locks.Condition
+import java.util.concurrent.locks.ReentrantLock
+import kotlin.concurrent.withLock
+
+/**
+ * A List that additionally offers the ability to append via the add() method, and to retrieve
+ * an element by its index optionally waiting for it to become available.
+ */
+interface TrackRecord<E> : List<E> {
+    /**
+     * Adds an element to this queue, waking up threads waiting for one. Returns true, as
+     * per the contract for List.
+     */
+    fun add(e: E): Boolean
+
+    /**
+     * Returns the first element after {@param pos}, possibly blocking until one is available, or
+     * null if no such element can be found within the timeout.
+     * If a predicate is given, only elements matching the predicate are returned.
+     *
+     * @param timeoutMs how long, in milliseconds, to wait at most (best effort approximation).
+     * @param pos the position at which to start polling.
+     * @param predicate an optional predicate to filter elements to be returned.
+     * @return an element matching the predicate, or null if timeout.
+     */
+    fun poll(timeoutMs: Long, pos: Int, predicate: (E) -> Boolean = { true }): E?
+}
+
+/**
+ * A thread-safe implementation of TrackRecord that is backed by an ArrayList.
+ *
+ * This class also supports the creation of a read-head for easier single-thread access.
+ * Refer to the documentation of {@link ArrayTrackRecord.ReadHead}.
+ */
+class ArrayTrackRecord<E> : TrackRecord<E> {
+    private val lock = ReentrantLock()
+    private val condition = lock.newCondition()
+    // Backing store. This stores the elements in this ArrayTrackRecord.
+    private val elements = ArrayList<E>()
+
+    // The list iterator for RecordingQueue iterates over a snapshot of the collection at the
+    // time the operator is created. Because TrackRecord is only ever mutated by appending,
+    // that makes this iterator thread-safe as it sees an effectively immutable List.
+    class ArrayTrackRecordIterator<E>(
+        private val list: ArrayList<E>,
+        start: Int,
+        private val end: Int
+    ) : ListIterator<E> {
+        var index = start
+        override fun hasNext() = index < end
+        override fun next() = list[index++]
+        override fun hasPrevious() = index > 0
+        override fun nextIndex() = index + 1
+        override fun previous() = list[--index]
+        override fun previousIndex() = index - 1
+    }
+
+    // List<E> implementation
+    override val size get() = lock.withLock { elements.size }
+    override fun contains(element: E) = lock.withLock { elements.contains(element) }
+    override fun containsAll(elements: Collection<E>) = lock.withLock {
+        this.elements.containsAll(elements)
+    }
+    override operator fun get(index: Int) = lock.withLock { elements[index] }
+    override fun indexOf(element: E): Int = lock.withLock { elements.indexOf(element) }
+    override fun lastIndexOf(element: E): Int = lock.withLock { elements.lastIndexOf(element) }
+    override fun isEmpty() = lock.withLock { elements.isEmpty() }
+    override fun listIterator(index: Int) = ArrayTrackRecordIterator(elements, index, size)
+    override fun listIterator() = listIterator(0)
+    override fun iterator() = listIterator()
+    override fun subList(fromIndex: Int, toIndex: Int): List<E> = lock.withLock {
+        elements.subList(fromIndex, toIndex)
+    }
+
+    // TrackRecord<E> implementation
+    override fun add(e: E): Boolean {
+        lock.withLock {
+            elements.add(e)
+            condition.signalAll()
+        }
+        return true
+    }
+    override fun poll(timeoutMs: Long, pos: Int, predicate: (E) -> Boolean) = lock.withLock {
+        elements.getOrNull(pollForIndexReadLocked(timeoutMs, pos, predicate))
+    }
+
+    // For convenience
+    fun getOrNull(pos: Int, predicate: (E) -> Boolean) = lock.withLock {
+        if (pos < 0 || pos > size) null else elements.subList(pos, size).find(predicate)
+    }
+
+    // Returns the index of the next element whose position is >= pos matching the predicate, if
+    // necessary waiting until such a time that such an element is available, with a timeout.
+    // If no such element is found within the timeout -1 is returned.
+    private fun pollForIndexReadLocked(timeoutMs: Long, pos: Int, predicate: (E) -> Boolean): Int {
+        val deadline = System.currentTimeMillis() + timeoutMs
+        var index = pos
+        do {
+            while (index < elements.size) {
+                if (predicate(elements[index])) return index
+                ++index
+            }
+        } while (condition.await(deadline - System.currentTimeMillis()))
+        return -1
+    }
+
+    /**
+     * Returns a ReadHead over this ArrayTrackRecord. The returned ReadHead is tied to the
+     * current thread.
+     */
+    fun newReadHead() = ReadHead()
+
+    /**
+     * ReadHead is an object that helps users of ArrayTrackRecord keep track of how far
+     * it has read this far in the ArrayTrackRecord. A ReadHead is always associated with
+     * a single instance of ArrayTrackRecord. Multiple ReadHeads can be created and used
+     * on the same instance of ArrayTrackRecord concurrently, and the ArrayTrackRecord
+     * instance can also be used concurrently. ReadHead maintains the current index that is
+     * the next to be read, and calls this the "mark".
+     *
+     * A ReadHead delegates all TrackRecord methods to its associated ArrayTrackRecord, and
+     * inherits its thread-safe properties. However, the additional methods that ReadHead
+     * offers on top of TrackRecord do not share these properties and can only be used by
+     * the thread that created the ReadHead. This is because by construction it does not
+     * make sense to use a ReadHead on multiple threads concurrently (see below for details).
+     *
+     * In a ReadHead, {@link poll(Long, (E) -> Boolean)} works similarly to a LinkedBlockingQueue.
+     * It can be called repeatedly and will return the elements as they arrive.
+     *
+     * Intended usage looks something like this :
+     * val TrackRecord<MyObject> record = ArrayTrackRecord().newReadHead()
+     * Thread().start {
+     *   // do stuff
+     *   record.add(something)
+     *   // do stuff
+     * }
+     *
+     * val obj1 = record.poll(timeout)
+     * // do something with obj1
+     * val obj2 = record.poll(timeout)
+     * // do something with obj2
+     *
+     * The point is that the caller does not have to track the mark like it would have to if
+     * it was using ArrayTrackRecord directly.
+     *
+     * Note that if multiple threads were using poll() concurrently on the same ReadHead, what
+     * happens to the mark and the return values could be well defined, but it could not
+     * be useful because there is no way to provide either a guarantee not to skip objects nor
+     * a guarantee about the mark position at the exit of poll(). This is even more true in the
+     * presence of a predicate to filter returned elements, because one thread might be
+     * filtering out the events the other is interested in.
+     * Instead, this use case is supported by creating multiple ReadHeads on the same instance
+     * of ArrayTrackRecord. Each ReadHead is then guaranteed to see all events always and
+     * guarantees are made on the value of the mark upon return. {@see poll(Long, (E) -> Boolean)}
+     * for details. Be careful to create each ReadHead on the thread it is meant to be used on.
+     *
+     * Users of a ReadHead can ask for the current position of the mark at any time. This mark
+     * can be used later to replay the history of events either on this ReadHead, on the associated
+     * ArrayTrackRecord or on another ReadHead associated with the same ArrayTrackRecord. It
+     * might look like this in the reader thread :
+     *
+     * val markAtStart = record.mark
+     * // Start processing interesting events
+     * while (val element = record.poll(timeout) { it.isInteresting() }) {
+     *   // Do something with element
+     * }
+     * // Look for stuff that happened while searching for interesting events
+     * val firstElementReceived = record.getOrNull(markAtStart)
+     * val firstSpecialElement = record.getOrNull(markAtStart) { it.isSpecial() }
+     * // Get the first special element since markAtStart, possibly blocking until one is available
+     * val specialElement = record.poll(timeout, markAtStart) { it.isSpecial() }
+     */
+    inner class ReadHead : TrackRecord<E> by this@ArrayTrackRecord {
+        private val owningThread = Thread.currentThread()
+        private var readHead = 0
+
+        /**
+         * @return the current value of the mark.
+         */
+        var mark
+            get() = readHead.also { checkThread() }
+            set(v: Int) = rewind(v)
+        fun rewind(v: Int) {
+            checkThread()
+            readHead = v
+        }
+
+        private fun checkThread() = check(Thread.currentThread() == owningThread) {
+            "Must be called by the thread that created this object"
+        }
+
+        /**
+         * Returns the first element after the mark, optionally blocking until one is available, or
+         * null if no such element can be found within the timeout.
+         * If a predicate is given, only elements matching the predicate are returned.
+         *
+         * Upon return the mark will be set to immediately after the returned element, or after
+         * the last element in the queue if null is returned. This means this method will always
+         * skip elements that do not match the predicate, even if it returns null.
+         *
+         * This method can only be used by the thread that created this ManagedRecordingQueue.
+         * If used on another thread, this throws IllegalStateException.
+         *
+         * @param timeoutMs how long, in milliseconds, to wait at most (best effort approximation).
+         * @param predicate an optional predicate to filter elements to be returned.
+         * @return an element matching the predicate, or null if timeout.
+         */
+        fun poll(timeoutMs: Long, predicate: (E) -> Boolean = { true }): E? {
+            checkThread()
+            lock.withLock {
+                val index = pollForIndexReadLocked(timeoutMs, readHead, predicate)
+                readHead = if (index < 0) size else index + 1
+                return getOrNull(index)
+            }
+        }
+
+        /**
+         * Returns the first element after the mark or null. This never blocks.
+         *
+         * This method can only be used by the thread that created this ManagedRecordingQueue.
+         * If used on another thread, this throws IllegalStateException.
+         */
+        fun peek(): E? = getOrNull(readHead).also { checkThread() }
+    }
+}
+
+// Private helper
+private fun Condition.await(timeoutMs: Long) = this.await(timeoutMs, TimeUnit.MILLISECONDS)
diff --git a/staticlibs/hostdevice/com/android/testutils/ConcurrentUtils.kt b/staticlibs/hostdevice/com/android/testutils/ConcurrentUtils.kt
new file mode 100644
index 0000000..a365af5
--- /dev/null
+++ b/staticlibs/hostdevice/com/android/testutils/ConcurrentUtils.kt
@@ -0,0 +1,26 @@
+/*
+ * 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 com.android.testutils
+
+import java.util.concurrent.CountDownLatch
+import java.util.concurrent.TimeUnit
+import kotlin.system.measureTimeMillis
+
+// For Java usage
+fun durationOf(fn: Runnable) = measureTimeMillis { fn.run() }
+
+fun CountDownLatch.await(timeoutMs: Long): Boolean = await(timeoutMs, TimeUnit.MILLISECONDS)
diff --git a/staticlibs/hostdevice/com/android/testutils/ExceptionUtils.java b/staticlibs/hostdevice/com/android/testutils/ExceptionUtils.java
new file mode 100644
index 0000000..e7dbed5
--- /dev/null
+++ b/staticlibs/hostdevice/com/android/testutils/ExceptionUtils.java
@@ -0,0 +1,67 @@
+/*
+ * 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 com.android.testutils;
+
+import java.util.function.Supplier;
+
+public class ExceptionUtils {
+    /**
+     * Like a Consumer, but declared to throw an exception.
+     * @param <T>
+     */
+    @FunctionalInterface
+    public interface ThrowingConsumer<T> {
+        void accept(T t) throws Exception;
+    }
+
+    /**
+     * Like a Supplier, but declared to throw an exception.
+     * @param <T>
+     */
+    @FunctionalInterface
+    public interface ThrowingSupplier<T> {
+        T get() throws Exception;
+    }
+
+    /**
+     * Like a Runnable, but declared to throw an exception.
+     */
+    @FunctionalInterface
+    public interface ThrowingRunnable {
+        void run() throws Exception;
+    }
+
+
+    public static <T> Supplier<T> ignoreExceptions(ThrowingSupplier<T> func) {
+        return () -> {
+            try {
+                return func.get();
+            } catch (Exception e) {
+                return null;
+            }
+        };
+    }
+
+    public static Runnable ignoreExceptions(ThrowingRunnable r) {
+        return () -> {
+            try {
+                r.run();
+            } catch (Exception e) {
+            }
+        };
+    }
+}
diff --git a/staticlibs/hostdevice/com/android/testutils/FileUtils.kt b/staticlibs/hostdevice/com/android/testutils/FileUtils.kt
new file mode 100644
index 0000000..678f977
--- /dev/null
+++ b/staticlibs/hostdevice/com/android/testutils/FileUtils.kt
@@ -0,0 +1,27 @@
+/*
+ * 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 com.android.testutils
+
+// This function is private because the 2 is hardcoded here, and is not correct if not called
+// directly from __LINE__ or __FILE__.
+private fun callerStackTrace(): StackTraceElement = try {
+    throw RuntimeException()
+} catch (e: RuntimeException) {
+    e.stackTrace[2] // 0 is here, 1 is get() in __FILE__ or __LINE__
+}
+val __FILE__: String get() = callerStackTrace().fileName
+val __LINE__: Int get() = callerStackTrace().lineNumber
diff --git a/staticlibs/hostdevice/com/android/testutils/MiscAsserts.kt b/staticlibs/hostdevice/com/android/testutils/MiscAsserts.kt
new file mode 100644
index 0000000..32c22c2
--- /dev/null
+++ b/staticlibs/hostdevice/com/android/testutils/MiscAsserts.kt
@@ -0,0 +1,103 @@
+/*
+ * 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 com.android.testutils
+
+import com.android.testutils.ExceptionUtils.ThrowingRunnable
+import java.lang.reflect.Modifier
+import kotlin.system.measureTimeMillis
+import kotlin.test.assertEquals
+import kotlin.test.assertFailsWith
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+private const val TAG = "Connectivity unit test"
+
+fun <T> assertEmpty(ts: Array<T>) = ts.size.let { len ->
+    assertEquals(0, len, "Expected empty array, but length was $len")
+}
+
+fun <T> assertLength(expected: Int, got: Array<T>) = got.size.let { len ->
+    assertEquals(expected, len, "Expected array of length $expected, but was $len for $got")
+}
+
+// Bridge method to help write this in Java. If you're writing Kotlin, consider using native
+// kotlin.test.assertFailsWith instead, as that method is reified and inlined.
+fun <T : Exception> assertThrows(expected: Class<T>, block: ThrowingRunnable): T {
+    return assertFailsWith(expected.kotlin) { block.run() }
+}
+
+fun <T : Exception> assertThrows(msg: String, expected: Class<T>, block: ThrowingRunnable): T {
+    return assertFailsWith(expected.kotlin, msg) { block.run() }
+}
+
+fun <T> assertEqualBothWays(o1: T, o2: T) {
+    assertTrue(o1 == o2)
+    assertTrue(o2 == o1)
+}
+
+fun <T> assertNotEqualEitherWay(o1: T, o2: T) {
+    assertFalse(o1 == o2)
+    assertFalse(o2 == o1)
+}
+
+fun assertStringContains(got: String, want: String) {
+    assertTrue(got.contains(want), "$got did not contain \"${want}\"")
+}
+
+fun assertContainsExactly(actual: IntArray, vararg expected: Int) {
+    // IntArray#sorted() returns a list, so it's fine to test with equals()
+    assertEquals(actual.sorted(), expected.sorted(),
+            "$actual does not contain exactly $expected")
+}
+
+fun assertContainsStringsExactly(actual: Array<String>, vararg expected: String) {
+    assertEquals(actual.sorted(), expected.sorted(),
+            "$actual does not contain exactly $expected")
+}
+
+fun <T> assertContainsAll(list: Collection<T>, vararg elems: T) {
+    assertContainsAll(list, elems.asList())
+}
+
+fun <T> assertContainsAll(list: Collection<T>, elems: Collection<T>) {
+    elems.forEach { assertTrue(list.contains(it), "$it not in list") }
+}
+
+fun assertRunsInAtMost(descr: String, timeLimit: Long, fn: Runnable) {
+    assertRunsInAtMost(descr, timeLimit) { fn.run() }
+}
+
+fun assertRunsInAtMost(descr: String, timeLimit: Long, fn: () -> Unit) {
+    val timeTaken = measureTimeMillis(fn)
+    val msg = String.format("%s: took %dms, limit was %dms", descr, timeTaken, timeLimit)
+    assertTrue(timeTaken <= timeLimit, msg)
+}
+
+/**
+ * Verifies that the number of nonstatic fields in a java class equals a given count.
+ * Note: this is essentially not useful for Kotlin code where fields are not really a thing.
+ *
+ * This assertion serves as a reminder to update test code around it if fields are added
+ * after the test is written.
+ * @param count Expected number of nonstatic fields in the class.
+ * @param clazz Class to test.
+ */
+fun <T> assertFieldCountEquals(count: Int, clazz: Class<T>) {
+    assertEquals(count, clazz.declaredFields.filter {
+        !Modifier.isStatic(it.modifiers) && !Modifier.isTransient(it.modifiers)
+    }.size)
+}
diff --git a/staticlibs/hostdevice/com/android/testutils/PacketFilter.kt b/staticlibs/hostdevice/com/android/testutils/PacketFilter.kt
new file mode 100644
index 0000000..cd8d6a5
--- /dev/null
+++ b/staticlibs/hostdevice/com/android/testutils/PacketFilter.kt
@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2020 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.testutils
+
+import java.util.function.Predicate
+
+const val ETHER_TYPE_OFFSET = 12
+const val ETHER_HEADER_LENGTH = 14
+const val IPV4_PROTOCOL_OFFSET = ETHER_HEADER_LENGTH + 9
+const val IPV4_CHECKSUM_OFFSET = ETHER_HEADER_LENGTH + 10
+const val IPV4_HEADER_LENGTH = 20
+const val IPV4_UDP_OFFSET = ETHER_HEADER_LENGTH + IPV4_HEADER_LENGTH
+const val BOOTP_OFFSET = IPV4_UDP_OFFSET + 8
+const val BOOTP_TID_OFFSET = BOOTP_OFFSET + 4
+const val BOOTP_CLIENT_MAC_OFFSET = BOOTP_OFFSET + 28
+const val DHCP_OPTIONS_OFFSET = BOOTP_OFFSET + 240
+
+/**
+ * A [Predicate] that matches a [ByteArray] if it contains the specified [bytes] at the specified
+ * [offset].
+ */
+class OffsetFilter(val offset: Int, vararg val bytes: Byte) : Predicate<ByteArray> {
+    override fun test(packet: ByteArray) =
+            bytes.withIndex().all { it.value == packet[offset + it.index] }
+}
+
+/**
+ * A [Predicate] that matches ethernet-encapped packets that contain an UDP over IPv4 datagram.
+ */
+class IPv4UdpFilter : Predicate<ByteArray> {
+    private val impl = OffsetFilter(ETHER_TYPE_OFFSET, 0x08, 0x00 /* IPv4 */).and(
+            OffsetFilter(IPV4_PROTOCOL_OFFSET, 17 /* UDP */))
+    override fun test(t: ByteArray) = impl.test(t)
+}
+
+/**
+ * A [Predicate] that matches ethernet-encapped DHCP packets sent from a DHCP client.
+ */
+class DhcpClientPacketFilter : Predicate<ByteArray> {
+    private val impl = IPv4UdpFilter()
+            .and(OffsetFilter(IPV4_UDP_OFFSET /* source port */, 0x00, 0x44 /* 68 */))
+            .and(OffsetFilter(IPV4_UDP_OFFSET + 2 /* dest port */, 0x00, 0x43 /* 67 */))
+    override fun test(t: ByteArray) = impl.test(t)
+}
+
+/**
+ * A [Predicate] that matches a [ByteArray] if it contains a ethernet-encapped DHCP packet that
+ * contains the specified option with the specified [bytes] as value.
+ */
+class DhcpOptionFilter(val option: Byte, vararg val bytes: Byte) : Predicate<ByteArray> {
+    override fun test(packet: ByteArray): Boolean {
+        val option = findDhcpOption(packet, option) ?: return false
+        return option.contentEquals(bytes)
+    }
+}
+
+/**
+ * Find a DHCP option in a packet and return its value, if found.
+ */
+fun findDhcpOption(packet: ByteArray, option: Byte): ByteArray? =
+        findOptionOffset(packet, option, DHCP_OPTIONS_OFFSET)?.let {
+            val optionLen = packet[it + 1]
+            return packet.copyOfRange(it + 2 /* type, length bytes */, it + 2 + optionLen)
+        }
+
+private tailrec fun findOptionOffset(packet: ByteArray, option: Byte, searchOffset: Int): Int? {
+    if (packet.size <= searchOffset + 2 /* type, length bytes */) return null
+
+    return if (packet[searchOffset] == option) searchOffset else {
+        val optionLen = packet[searchOffset + 1]
+        findOptionOffset(packet, option, searchOffset + 2 + optionLen)
+    }
+}
diff --git a/staticlibs/hostdevice/com/android/testutils/SkipPresubmit.kt b/staticlibs/hostdevice/com/android/testutils/SkipPresubmit.kt
new file mode 100644
index 0000000..69ed048
--- /dev/null
+++ b/staticlibs/hostdevice/com/android/testutils/SkipPresubmit.kt
@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2020 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.testutils
+
+/**
+ * Skip the test in presubmit runs for the reason specified in [reason].
+ *
+ * This annotation is typically used to document hardware or test bench limitations.
+ */
+annotation class SkipPresubmit(val reason: String)
\ No newline at end of file
diff --git a/staticlibs/jarjar-rules-shared.txt b/staticlibs/jarjar-rules-shared.txt
index b22771d..9e618db 100644
--- a/staticlibs/jarjar-rules-shared.txt
+++ b/staticlibs/jarjar-rules-shared.txt
@@ -1,3 +1,8 @@
-rule android.net.util.** com.android.net.module.util.@1
+# TODO: move the classes to the target package in java
+rule android.net.util.IpRange* com.android.net.module.util.IpRange@1
+rule android.net.util.MacAddressUtils* com.android.net.module.util.MacAddressUtils@1
+rule android.net.util.LinkPropertiesUtils* com.android.net.module.util.LinkPropertiesUtils@1
+rule android.net.util.NetUtils* com.android.net.module.util.NetUtils@1
+rule android.net.util.nsd.** com.android.net.module.util.nsd.@1
 rule android.annotation.** com.android.net.module.annotation.@1
-rule com.android.internal.annotations.** com.android.net.module.annotation.@1
\ No newline at end of file
+rule com.android.internal.annotations.** com.android.net.module.annotation.@1
diff --git a/staticlibs/tests/unit/Android.bp b/staticlibs/tests/unit/Android.bp
index cb15277..f18ffcf 100644
--- a/staticlibs/tests/unit/Android.bp
+++ b/staticlibs/tests/unit/Android.bp
@@ -10,6 +10,8 @@
     static_libs: [
         "net-utils-framework-common",
         "androidx.test.rules",
+        "net-utils-device-common",
+        "net-tests-utils-host-device-common",
     ],
     libs: [
         "android.test.runner",
diff --git a/staticlibs/tests/unit/jarjar-rules.txt b/staticlibs/tests/unit/jarjar-rules.txt
index dbb3974..fceccfb 100644
--- a/staticlibs/tests/unit/jarjar-rules.txt
+++ b/staticlibs/tests/unit/jarjar-rules.txt
@@ -1,4 +1,6 @@
-# Ensure that the tests can directly use the version of classes from the library. Otherwise, they
-# will use whatever version is currently in the bootclasspath on the device running the test.
-# These rules must match the jarjar rules used to build the library.
-rule android.net.util.** com.android.net.module.util.@1
+# TODO: move the classes to the target package in java
+rule android.net.util.IpRange* com.android.net.module.util.IpRange@1
+rule android.net.util.MacAddressUtils* com.android.net.module.util.MacAddressUtils@1
+rule android.net.util.LinkPropertiesUtils* com.android.net.module.util.LinkPropertiesUtils@1
+rule android.net.util.NetUtils* com.android.net.module.util.NetUtils@1
+rule android.net.util.nsd.** com.android.net.module.util.nsd.@1
diff --git a/staticlibs/tests/unit/src/com/android/net/module/util/PacketReaderTest.java b/staticlibs/tests/unit/src/com/android/net/module/util/PacketReaderTest.java
new file mode 100644
index 0000000..e3af97e
--- /dev/null
+++ b/staticlibs/tests/unit/src/com/android/net/module/util/PacketReaderTest.java
@@ -0,0 +1,248 @@
+/*
+ * Copyright (C) 2016 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.net.module.util;
+
+import static android.net.util.PacketReader.DEFAULT_RECV_BUF_SIZE;
+import static android.system.OsConstants.AF_INET6;
+import static android.system.OsConstants.IPPROTO_UDP;
+import static android.system.OsConstants.SOCK_DGRAM;
+import static android.system.OsConstants.SOCK_NONBLOCK;
+import static android.system.OsConstants.SOL_SOCKET;
+import static android.system.OsConstants.SO_SNDTIMEO;
+
+import static com.android.testutils.MiscAssertsKt.assertThrows;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import android.net.util.PacketReader;
+import android.os.Handler;
+import android.os.HandlerThread;
+import android.system.ErrnoException;
+import android.system.Os;
+import android.system.StructTimeval;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.io.FileDescriptor;
+import java.net.DatagramPacket;
+import java.net.DatagramSocket;
+import java.net.Inet6Address;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.SocketException;
+import java.util.Arrays;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Tests for PacketReader.
+ *
+ * @hide
+ */
+@RunWith(AndroidJUnit4.class)
+@SmallTest
+public class PacketReaderTest {
+    static final InetAddress LOOPBACK6 = Inet6Address.getLoopbackAddress();
+    static final StructTimeval TIMEO = StructTimeval.fromMillis(500);
+
+    // TODO : reassigning the latch voids its synchronization properties, which means this
+    // scheme just doesn't work. Latches almost always need to be final to work.
+    protected CountDownLatch mLatch;
+    protected FileDescriptor mLocalSocket;
+    protected InetSocketAddress mLocalSockName;
+    protected byte[] mLastRecvBuf;
+    protected boolean mStopped;
+    protected HandlerThread mHandlerThread;
+    protected PacketReader mReceiver;
+
+    class UdpLoopbackReader extends PacketReader {
+        UdpLoopbackReader(Handler h) {
+            super(h);
+        }
+
+        @Override
+        protected FileDescriptor createFd() {
+            FileDescriptor s = null;
+            try {
+                s = Os.socket(AF_INET6, SOCK_DGRAM | SOCK_NONBLOCK, IPPROTO_UDP);
+                Os.bind(s, LOOPBACK6, 0);
+                mLocalSockName = (InetSocketAddress) Os.getsockname(s);
+                Os.setsockoptTimeval(s, SOL_SOCKET, SO_SNDTIMEO, TIMEO);
+            } catch (ErrnoException | SocketException e) {
+                closeFd(s);
+                fail();
+                return null;
+            }
+
+            mLocalSocket = s;
+            return s;
+        }
+
+        @Override
+        protected void handlePacket(byte[] recvbuf, int length) {
+            mLastRecvBuf = Arrays.copyOf(recvbuf, length);
+            mLatch.countDown();
+        }
+
+        @Override
+        protected void onStart() {
+            mStopped = false;
+            mLatch.countDown();
+        }
+
+        @Override
+        protected void onStop() {
+            mStopped = true;
+            mLatch.countDown();
+        }
+    };
+
+    @Before
+    public void setUp() {
+        resetLatch();
+        mLocalSocket = null;
+        mLocalSockName = null;
+        mLastRecvBuf = null;
+        mStopped = false;
+
+        mHandlerThread = new HandlerThread(PacketReaderTest.class.getSimpleName());
+        mHandlerThread.start();
+    }
+
+    @After
+    public void tearDown() throws Exception {
+        if (mReceiver != null) {
+            mHandlerThread.getThreadHandler().post(() -> mReceiver.stop());
+            waitForActivity();
+        }
+        mReceiver = null;
+        mHandlerThread.quit();
+        mHandlerThread = null;
+    }
+
+    void resetLatch() {
+        mLatch = new CountDownLatch(1);
+    }
+
+    void waitForActivity() throws Exception {
+        try {
+            mLatch.await(1000, TimeUnit.MILLISECONDS);
+        } finally {
+            resetLatch();
+        }
+    }
+
+    void sendPacket(byte[] contents) throws Exception {
+        final DatagramSocket sender = new DatagramSocket();
+        sender.connect(mLocalSockName);
+        sender.send(new DatagramPacket(contents, contents.length));
+        sender.close();
+    }
+
+    @Test
+    public void testBasicWorking() throws Exception {
+        final Handler h = mHandlerThread.getThreadHandler();
+        mReceiver = new UdpLoopbackReader(h);
+
+        h.post(() -> mReceiver.start());
+        waitForActivity();
+        assertTrue(mLocalSockName != null);
+        assertEquals(LOOPBACK6, mLocalSockName.getAddress());
+        assertTrue(0 < mLocalSockName.getPort());
+        assertTrue(mLocalSocket != null);
+        assertFalse(mStopped);
+
+        final byte[] one = "one 1".getBytes("UTF-8");
+        sendPacket(one);
+        waitForActivity();
+        assertEquals(1, mReceiver.numPacketsReceived());
+        assertTrue(Arrays.equals(one, mLastRecvBuf));
+        assertFalse(mStopped);
+
+        final byte[] two = "two 2".getBytes("UTF-8");
+        sendPacket(two);
+        waitForActivity();
+        assertEquals(2, mReceiver.numPacketsReceived());
+        assertTrue(Arrays.equals(two, mLastRecvBuf));
+        assertFalse(mStopped);
+
+        h.post(() -> mReceiver.stop());
+        waitForActivity();
+        assertEquals(2, mReceiver.numPacketsReceived());
+        assertTrue(Arrays.equals(two, mLastRecvBuf));
+        assertTrue(mStopped);
+        mReceiver = null;
+    }
+
+    class NullPacketReader extends PacketReader {
+        NullPacketReader(Handler h, int recvbufsize) {
+            super(h, recvbufsize);
+        }
+
+        @Override
+        public FileDescriptor createFd() {
+            return null;
+        }
+    }
+
+    @Test
+    public void testMinimalRecvBufSize() throws Exception {
+        final Handler h = mHandlerThread.getThreadHandler();
+
+        for (int i : new int[] { -1, 0, 1, DEFAULT_RECV_BUF_SIZE - 1 }) {
+            final PacketReader b = new NullPacketReader(h, i);
+            assertEquals(DEFAULT_RECV_BUF_SIZE, b.recvBufSize());
+        }
+    }
+
+    @Test
+    public void testStartingFromWrongThread() throws Exception {
+        final Handler h = mHandlerThread.getThreadHandler();
+        final PacketReader b = new NullPacketReader(h, DEFAULT_RECV_BUF_SIZE);
+        assertThrows(IllegalStateException.class, () -> b.start());
+    }
+
+    @Test
+    public void testStoppingFromWrongThread() throws Exception {
+        final Handler h = mHandlerThread.getThreadHandler();
+        final PacketReader b = new NullPacketReader(h, DEFAULT_RECV_BUF_SIZE);
+        assertThrows(IllegalStateException.class, () -> b.stop());
+    }
+
+    @Test
+    public void testSuccessToCreateSocket() throws Exception {
+        final Handler h = mHandlerThread.getThreadHandler();
+        final PacketReader b = new UdpLoopbackReader(h);
+        h.post(() -> assertTrue(b.start()));
+    }
+
+    @Test
+    public void testFailToCreateSocket() throws Exception {
+        final Handler h = mHandlerThread.getThreadHandler();
+        final PacketReader b = new NullPacketReader(h, DEFAULT_RECV_BUF_SIZE);
+        h.post(() -> assertFalse(b.start()));
+    }
+}