Rename TapPacketReader to PollPacketReader for broader applicability

* Renamed TapPacketReader to PollPacketReader to better reflect its
  functionality beyond TAP interface interaction.
* The class includes general logic for polling and sending packets to
  file descriptors, making it suitable for wider use cases.

Test: TH
Change-Id: Icdf9a9d7ef6f49b589ed9cdbd05159ab95e7e5d9
diff --git a/staticlibs/testutils/devicetests/NSResponder.kt b/staticlibs/testutils/devicetests/NSResponder.kt
index f7619cd..f094407 100644
--- a/staticlibs/testutils/devicetests/NSResponder.kt
+++ b/staticlibs/testutils/devicetests/NSResponder.kt
@@ -35,12 +35,12 @@
 private const val NS_TYPE = 135.toShort()
 
 /**
- * A class that can be used to reply to Neighbor Solicitation packets on a [TapPacketReader].
+ * A class that can be used to reply to Neighbor Solicitation packets on a [PollPacketReader].
  */
 class NSResponder(
-    reader: TapPacketReader,
-    table: Map<Inet6Address, MacAddress>,
-    name: String = NSResponder::class.java.simpleName
+        reader: PollPacketReader,
+        table: Map<Inet6Address, MacAddress>,
+        name: String = NSResponder::class.java.simpleName
 ) : PacketResponder(reader, Icmpv6Filter(), name) {
     companion object {
         private val TAG = NSResponder::class.simpleName
@@ -49,7 +49,7 @@
     // Copy the map if not already immutable (toMap) to make sure it is not modified
     private val table = table.toMap()
 
-    override fun replyToPacket(packet: ByteArray, reader: TapPacketReader) {
+    override fun replyToPacket(packet: ByteArray, reader: PollPacketReader) {
         if (packet.size < IPV6_HEADER_LENGTH) {
             return
         }
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/ArpResponder.kt b/staticlibs/testutils/devicetests/com/android/testutils/ArpResponder.kt
index cf0490c..f4c8657 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/ArpResponder.kt
+++ b/staticlibs/testutils/devicetests/com/android/testutils/ArpResponder.kt
@@ -30,17 +30,17 @@
 private val ARP_REPLY_IPV4 = byteArrayOf(0x00, 0x01, 0x08, 0x00, 0x06, 0x04, 0x00, 0x02)
 
 /**
- * A class that can be used to reply to ARP packets on a [TapPacketReader].
+ * A class that can be used to reply to ARP packets on a [PollPacketReader].
  */
 class ArpResponder(
-    reader: TapPacketReader,
-    table: Map<Inet4Address, MacAddress>,
-    name: String = ArpResponder::class.java.simpleName
+        reader: PollPacketReader,
+        table: Map<Inet4Address, MacAddress>,
+        name: String = ArpResponder::class.java.simpleName
 ) : PacketResponder(reader, ArpRequestFilter(), name) {
     // Copy the map if not already immutable (toMap) to make sure it is not modified
     private val table = table.toMap()
 
-    override fun replyToPacket(packet: ByteArray, reader: TapPacketReader) {
+    override fun replyToPacket(packet: ByteArray, reader: PollPacketReader) {
         val targetIp = InetAddress.getByAddress(
                 packet.copyFromIndexWithLength(ARP_TARGET_IPADDR_OFFSET, 4))
                 as Inet4Address
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/MdnsTestUtils.kt b/staticlibs/testutils/devicetests/com/android/testutils/MdnsTestUtils.kt
index 8b88224..5729452 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/MdnsTestUtils.kt
+++ b/staticlibs/testutils/devicetests/com/android/testutils/MdnsTestUtils.kt
@@ -28,8 +28,6 @@
 import com.android.net.module.util.NetworkStackConstants.IPV6_HEADER_LEN
 import com.android.net.module.util.NetworkStackConstants.UDP_HEADER_LEN
 import com.android.net.module.util.TrackRecord
-import com.android.testutils.IPv6UdpFilter
-import com.android.testutils.TapPacketReader
 import java.net.Inet6Address
 import java.net.InetAddress
 import kotlin.test.assertEquals
@@ -246,7 +244,7 @@
             as Inet6Address
 }
 
-fun TapPacketReader.pollForMdnsPacket(
+fun PollPacketReader.pollForMdnsPacket(
     timeoutMs: Long = MDNS_REGISTRATION_TIMEOUT_MS,
     predicate: (TestDnsPacket) -> Boolean
 ): TestDnsPacket? {
@@ -264,7 +262,7 @@
     }
 }
 
-fun TapPacketReader.pollForProbe(
+fun PollPacketReader.pollForProbe(
     serviceName: String,
     serviceType: String,
     timeoutMs: Long = MDNS_REGISTRATION_TIMEOUT_MS
@@ -272,7 +270,7 @@
     it.isProbeFor("$serviceName.$serviceType.local")
 }
 
-fun TapPacketReader.pollForAdvertisement(
+fun PollPacketReader.pollForAdvertisement(
     serviceName: String,
     serviceType: String,
     timeoutMs: Long = MDNS_REGISTRATION_TIMEOUT_MS
@@ -280,19 +278,19 @@
     it.isReplyFor("$serviceName.$serviceType.local")
 }
 
-fun TapPacketReader.pollForQuery(
+fun PollPacketReader.pollForQuery(
     recordName: String,
     vararg requiredTypes: Int,
     timeoutMs: Long = MDNS_REGISTRATION_TIMEOUT_MS
 ): TestDnsPacket? = pollForMdnsPacket(timeoutMs) { it.isQueryFor(recordName, *requiredTypes) }
 
-fun TapPacketReader.pollForReply(
+fun PollPacketReader.pollForReply(
     recordName: String,
     type: Int,
     timeoutMs: Long = MDNS_REGISTRATION_TIMEOUT_MS
 ): TestDnsPacket? = pollForMdnsPacket(timeoutMs) { it.isReplyFor(recordName, type) }
 
-fun TapPacketReader.pollForReply(
+fun PollPacketReader.pollForReply(
     serviceName: String,
     serviceType: String,
     timeoutMs: Long = MDNS_REGISTRATION_TIMEOUT_MS
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/PacketResponder.kt b/staticlibs/testutils/devicetests/com/android/testutils/PacketResponder.kt
index 964c6c6..62d0e82 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/PacketResponder.kt
+++ b/staticlibs/testutils/devicetests/com/android/testutils/PacketResponder.kt
@@ -21,24 +21,24 @@
 private const val POLL_FREQUENCY_MS = 1000L
 
 /**
- * A class that can be used to reply to packets from a [TapPacketReader].
+ * A class that can be used to reply to packets from a [PollPacketReader].
  *
  * A reply thread will be created to reply to incoming packets asynchronously.
- * The receiver creates a new read head on the [TapPacketReader], to read packets, so it does not
- * affect packets obtained through [TapPacketReader.popPacket].
+ * The receiver creates a new read head on the [PollPacketReader], to read packets, so it does not
+ * affect packets obtained through [PollPacketReader.popPacket].
  *
- * @param reader a [TapPacketReader] to obtain incoming packets and reply to them.
+ * @param reader a [PollPacketReader] to obtain incoming packets and reply to them.
  * @param packetFilter A filter to apply to incoming packets.
  * @param name Name to use for the internal responder thread.
  */
 abstract class PacketResponder(
-    private val reader: TapPacketReader,
-    private val packetFilter: Predicate<ByteArray>,
-    name: String
+        private val reader: PollPacketReader,
+        private val packetFilter: Predicate<ByteArray>,
+        name: String
 ) {
     private val replyThread = ReplyThread(name)
 
-    protected abstract fun replyToPacket(packet: ByteArray, reader: TapPacketReader)
+    protected abstract fun replyToPacket(packet: ByteArray, reader: PollPacketReader)
 
     /**
      * Start the [PacketResponder].
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/TapPacketReader.java b/staticlibs/testutils/devicetests/com/android/testutils/PollPacketReader.java
similarity index 91%
rename from staticlibs/testutils/devicetests/com/android/testutils/TapPacketReader.java
rename to staticlibs/testutils/devicetests/com/android/testutils/PollPacketReader.java
index b25b9f2..dbc7eb0 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/TapPacketReader.java
+++ b/staticlibs/testutils/devicetests/com/android/testutils/PollPacketReader.java
@@ -35,19 +35,19 @@
 import kotlin.LazyKt;
 
 /**
- * A packet reader that runs on a TAP interface.
+ * A packet reader that can poll for received packets and send responses on a fd.
  *
  * It also implements facilities to reply to received packets.
  */
-public class TapPacketReader extends PacketReader {
-    private final FileDescriptor mTapFd;
+public class PollPacketReader extends PacketReader {
+    private final FileDescriptor mFd;
     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) {
+    public PollPacketReader(Handler h, FileDescriptor fd, int maxPacketSize) {
         super(h, maxPacketSize);
-        mTapFd = tapFd;
+        mFd = fd;
     }
 
 
@@ -63,7 +63,7 @@
 
     @Override
     protected FileDescriptor createFd() {
-        return mTapFd;
+        return mFd;
     }
 
     @Override
@@ -119,7 +119,7 @@
     }
 
     /*
-     * Send a response on the TAP interface.
+     * Send a response on the fd.
      *
      * The passed ByteBuffer is flipped after use.
      *
@@ -127,7 +127,7 @@
      * @throws IOException if the interface can't be written to.
      */
     public void sendResponse(final ByteBuffer packet) throws IOException {
-        try (FileOutputStream out = new FileOutputStream(mTapFd)) {
+        try (FileOutputStream out = new FileOutputStream(mFd)) {
             byte[] packetBytes = new byte[packet.limit()];
             packet.get(packetBytes);
             packet.flip();  // So we can reuse it in the future.
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/RouterAdvertisementResponder.java b/staticlibs/testutils/devicetests/com/android/testutils/RouterAdvertisementResponder.java
index 51d57bc..6709555 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/RouterAdvertisementResponder.java
+++ b/staticlibs/testutils/devicetests/com/android/testutils/RouterAdvertisementResponder.java
@@ -62,18 +62,18 @@
     private static final String TAG = "RouterAdvertisementResponder";
     private static final Inet6Address DNS_SERVER =
             (Inet6Address) InetAddresses.parseNumericAddress("2001:4860:4860::64");
-    private final TapPacketReader mPacketReader;
+    private final PollPacketReader mPacketReader;
     // Maps IPv6 address to MacAddress and isRouter boolean.
     private final Map<Inet6Address, Pair<MacAddress, Boolean>> mNeighborMap = new ArrayMap<>();
     private final IpPrefix mPrefix;
 
-    public RouterAdvertisementResponder(TapPacketReader packetReader, IpPrefix prefix) {
+    public RouterAdvertisementResponder(PollPacketReader packetReader, IpPrefix prefix) {
         super(packetReader, RouterAdvertisementResponder::isRsOrNs, TAG);
         mPacketReader = packetReader;
         mPrefix = Objects.requireNonNull(prefix);
     }
 
-    public RouterAdvertisementResponder(TapPacketReader packetReader) {
+    public RouterAdvertisementResponder(PollPacketReader packetReader) {
         this(packetReader, makeRandomPrefix());
     }
 
@@ -148,7 +148,7 @@
                 buildSllaOption(srcMac));
     }
 
-    private static void sendResponse(TapPacketReader reader, ByteBuffer buffer) {
+    private static void sendResponse(PollPacketReader reader, ByteBuffer buffer) {
         try {
             reader.sendResponse(buffer);
         } catch (IOException e) {
@@ -158,7 +158,7 @@
         }
     }
 
-    private void replyToRouterSolicitation(TapPacketReader reader, MacAddress dstMac) {
+    private void replyToRouterSolicitation(PollPacketReader reader, MacAddress dstMac) {
         for (Map.Entry<Inet6Address, Pair<MacAddress, Boolean>> it : mNeighborMap.entrySet()) {
             final boolean isRouter = it.getValue().second;
             if (!isRouter) {
@@ -169,7 +169,7 @@
         }
     }
 
-    private void replyToNeighborSolicitation(TapPacketReader reader, MacAddress dstMac,
+    private void replyToNeighborSolicitation(PollPacketReader reader, MacAddress dstMac,
             Inet6Address dstIp, Inet6Address targetIp) {
         final Pair<MacAddress, Boolean> neighbor = mNeighborMap.get(targetIp);
         if (neighbor == null) {
@@ -190,7 +190,7 @@
     }
 
     @Override
-    protected void replyToPacket(byte[] packet, TapPacketReader reader) {
+    protected void replyToPacket(byte[] packet, PollPacketReader reader) {
         final ByteBuffer buf = ByteBuffer.wrap(packet);
         // Messages are filtered by parent class, so it is safe to assume that packet is either an
         // RS or NS.
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/TapPacketReaderRule.kt b/staticlibs/testutils/devicetests/com/android/testutils/TapPacketReaderRule.kt
index 701666c..adf7619 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/TapPacketReaderRule.kt
+++ b/staticlibs/testutils/devicetests/com/android/testutils/TapPacketReaderRule.kt
@@ -31,9 +31,9 @@
 private const val HANDLER_TIMEOUT_MS = 10_000L
 
 /**
- * A [TestRule] that sets up a [TapPacketReader] on a [TestNetworkInterface] for use in the test.
+ * A [TestRule] that sets up a [PollPacketReader] on a [TestNetworkInterface] for use in the test.
  *
- * @param maxPacketSize Maximum size of packets read in the [TapPacketReader] buffer.
+ * @param maxPacketSize Maximum size of packets read in the [PollPacketReader] buffer.
  * @param autoStart Whether to initialize the interface and start the reader automatically for every
  *                  test. If false, each test must either call start() and stop(), or be annotated
  *                  with TapPacketReaderTest before using the reader or interface.
@@ -50,21 +50,21 @@
     // referenced before they could be initialized (typically if autoStart is false and the test
     // does not call start or use @TapPacketReaderTest).
     lateinit var iface: TestNetworkInterface
-    lateinit var reader: TapPacketReader
+    lateinit var reader: PollPacketReader
 
     @Volatile
     private var readerRunning = false
 
     /**
      * Indicates that the [TapPacketReaderRule] should initialize its [TestNetworkInterface] and
-     * start the [TapPacketReader] before the test, and tear them down afterwards.
+     * start the [PollPacketReader] before the test, and tear them down afterwards.
      *
      * For use when [TapPacketReaderRule] is created with autoStart = false.
      */
     annotation class TapPacketReaderTest
 
     /**
-     * Initialize the tap interface and start the [TapPacketReader].
+     * Initialize the tap interface and start the [PollPacketReader].
      *
      * Tests using this method must also call [stop] before exiting.
      * @param handler Handler to run the reader on. Callers are responsible for safely terminating
@@ -85,13 +85,13 @@
         }
         val usedHandler = handler ?: HandlerThread(
                 TapPacketReaderRule::class.java.simpleName).apply { start() }.threadHandler
-        reader = TapPacketReader(usedHandler, iface.fileDescriptor.fileDescriptor, maxPacketSize)
+        reader = PollPacketReader(usedHandler, iface.fileDescriptor.fileDescriptor, maxPacketSize)
         reader.startAsyncForTest()
         readerRunning = true
     }
 
     /**
-     * Stop the [TapPacketReader].
+     * Stop the [PollPacketReader].
      *
      * Tests calling [start] must call this method before exiting. If a handler was specified in
      * [start], all messages on that handler must also be processed after calling this method and