[BR01.1] Support BpfNetMapsReader

A helper class to *read* java BpfMaps. This is designed to
provide direct bpf access in the caller process through
ConnectivityManager APIs.

The change also removes any statical link to
net-utils-device-common-struct from service-connectivity.
This is because net-utils-device-common-struct is already
included in framework-connectivity. Including it again in
service-connectivity would create a r8 build fail by circular
dependency.

Test: atest FrameworksNetTests:android.net.connectivity.com.android.server.BpfNetMapsTest
Test: atest ConnectivityCoverageTests:android.net.connectivity.com.android.net.module.util.StructTest
Test: atest FrameworksNetTests:android.net.connectivity.android.net.BpfNetMapsReaderTest
Bug: 297836825
Change-Id: I7a6d2eb816d0dc7343167bddd672806b199f44fe

tests/unit/java/android/net/BpfNetMapsReaderTest.kt

@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2023 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 android.net
+
+import android.net.BpfNetMapsConstants.UID_RULES_CONFIGURATION_KEY
+import android.net.BpfNetMapsUtils.getMatchByFirewallChain
+import android.os.Build
+import com.android.net.module.util.IBpfMap
+import com.android.net.module.util.Struct.S32
+import com.android.net.module.util.Struct.U32
+import com.android.testutils.DevSdkIgnoreRule.IgnoreUpTo
+import com.android.testutils.DevSdkIgnoreRunner
+import com.android.testutils.TestBpfMap
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+
+// pre-T devices does not support Bpf.
+@RunWith(DevSdkIgnoreRunner::class)
+@IgnoreUpTo(Build.VERSION_CODES.S_V2)
+class BpfNetMapsReaderTest {
+    private val testConfigurationMap: IBpfMap<S32, U32> = TestBpfMap()
+    private val testUidOwnerMap: IBpfMap<S32, UidOwnerValue> = TestBpfMap()
+    private val bpfNetMapsReader = BpfNetMapsReader(
+        TestDependencies(testConfigurationMap, testUidOwnerMap))
+
+    class TestDependencies(
+        private val configMap: IBpfMap<S32, U32>,
+        private val uidOwnerMap: IBpfMap<S32, UidOwnerValue>
+    ) : BpfNetMapsReader.Dependencies() {
+        override fun getConfigurationMap() = configMap
+        override fun getUidOwnerMap() = uidOwnerMap
+    }
+
+    private fun doTestIsChainEnabled(chain: Int) {
+        testConfigurationMap.updateEntry(
+            UID_RULES_CONFIGURATION_KEY,
+            U32(getMatchByFirewallChain(chain))
+        )
+        assertTrue(bpfNetMapsReader.isChainEnabled(chain))
+        testConfigurationMap.updateEntry(UID_RULES_CONFIGURATION_KEY, U32(0))
+        assertFalse(bpfNetMapsReader.isChainEnabled(chain))
+    }
+
+    @Test
+    @Throws(Exception::class)
+    fun testIsChainEnabled() {
+        doTestIsChainEnabled(ConnectivityManager.FIREWALL_CHAIN_DOZABLE)
+        doTestIsChainEnabled(ConnectivityManager.FIREWALL_CHAIN_STANDBY)
+        doTestIsChainEnabled(ConnectivityManager.FIREWALL_CHAIN_POWERSAVE)
+        doTestIsChainEnabled(ConnectivityManager.FIREWALL_CHAIN_RESTRICTED)
+        doTestIsChainEnabled(ConnectivityManager.FIREWALL_CHAIN_LOW_POWER_STANDBY)
+    }
+}