Add TestNetworkTracker to test utils.

The tracker allows easily creating valid Network objects that are based
on test (TUN) interfaces.
It is taken from GTS NetworkStack test code and adapted to Kotlin.

Test: tests based on this class (e.g. CaptivePortalLoginTests)
Bug: 131401028
Merged-In: I6f8d1e36670c46ebcbca01e0a64ce579bcdcc1f9
Change-Id: I6f8d1e36670c46ebcbca01e0a64ce579bcdcc1f9

1 files changed, 92 insertions, 0 deletions

diff --git a/tests/lib/src/com/android/testutils/TestNetworkTracker.kt b/tests/lib/src/com/android/testutils/TestNetworkTracker.kt
new file mode 100644
index 0000000..4bd9ae8
--- /dev/null
+++ b/tests/lib/src/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)
+    }
+}
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