Add utilities to test tap interface networks
Add an ArpResponder based on a generic PacketResponder class, and a
TestHttpServer based on NanoHttpd.
Test: tests based on these utilities
Bug: 160617623
Bug: 160656765
Change-Id: I50b872a8b23e8df997e8f62f0adc7c0256c4d74d
diff --git a/staticlibs/devicetests/com/android/testutils/PacketResponder.kt b/staticlibs/devicetests/com/android/testutils/PacketResponder.kt
new file mode 100644
index 0000000..daf29e4
--- /dev/null
+++ b/staticlibs/devicetests/com/android/testutils/PacketResponder.kt
@@ -0,0 +1,74 @@
+/*
+ * 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
+
+private const val POLL_FREQUENCY_MS = 1000L
+
+/**
+ * A class that can be used to reply to packets from a [TapPacketReader].
+ *
+ * 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].
+ *
+ * @param reader a [TapPacketReader] 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 replyThread = ReplyThread(name)
+
+ protected abstract fun replyToPacket(packet: ByteArray, reader: TapPacketReader)
+
+ /**
+ * Start the [PacketResponder].
+ */
+ fun start() {
+ replyThread.start()
+ }
+
+ /**
+ * Stop the [PacketResponder].
+ *
+ * The responder cannot be used anymore after being stopped.
+ */
+ fun stop() {
+ replyThread.interrupt()
+ }
+
+ private inner class ReplyThread(name: String) : Thread(name) {
+ override fun run() {
+ try {
+ // Create a new ReadHead so other packets polled on the reader are not affected
+ val recvPackets = reader.receivedPackets.newReadHead()
+ while (!isInterrupted) {
+ recvPackets.poll(POLL_FREQUENCY_MS, packetFilter::test)?.let {
+ replyToPacket(it, reader)
+ }
+ }
+ } catch (e: InterruptedException) {
+ // Exit gracefully
+ }
+ }
+ }
+}