Add build target for NetworkStack on API 29

NetworkStack will need at least two different build targets: one for the
in-progress SDK for testing before release, and one for the latest
released SDK for releasing to production.

The difference in available APIs is abstracted from the core code by
using shims, with one shim for the released SDK that uses fallback code,
and one shim for the in-progress SDK that calls the actual new API.
The shim included in the built code depends on the build target.

AOSP does not yet have prebuilts for API 29, so the build rule still
references system_current for now.

Test: atest NetworkStackTests
Test: flashed, WiFi working
Test: aapt dump xmltree NetworkStack.apk AndroidManifest.xml: no change
Test: m NetworkStackApiStable (on a branch that has the prebuilt SDK)
Change-Id: I9cf8e712b56a8aad8656eb5095ac8a32f4a05037

6 files changed, 234 insertions, 43 deletions

diff --git a/Android.bp b/Android.bp
index 2e71c75..ba2e424 100644
--- a/Android.bp
+++ b/Android.bp
@@ -14,6 +14,26 @@
 // limitations under the License.
 //
 
+// The network stack can be compiled using system_current (non-finalized) SDK, or finalized system_X
+// SDK. There is also a variant that uses system_current SDK and runs in the system process
+// (InProcessNetworkStack). The following structure is used to create the build rules:
+//
+//                          NetworkStackAndroidLibraryDefaults <-- common defaults for android libs
+//                                     /           \
+//    +NetworkStackApiStableShims --> /             \ <-- +NetworkStackApiCurrentShims
+//    +NetworkStackApiStableLevel    /               \    +NetworkStackApiCurrentLevel
+//                                  /                 \
+//           NetworkStackApiStableLib         NetworkStackApiCurrentLib <-- android libs w/ all code
+//                     |                                     |             (also used in unit tests)
+//                     | <--   +NetworkStackAppDefaults  --> |
+//                     |          (APK build params)         |
+//                     |                                     |
+//                     | <-- +NetworkStackApiStableLevel     | <-- +NetworkStackApiCurrentLevel
+//                     |                                     |
+//                     |                                     |
+//           NetworkStackApiStable          NetworkStack, InProcessNetworkStack, <-- output APKs
+//                                                    TestNetworkStack
+
 java_library {
     name: "captiveportal-lib",
     srcs: ["common/**/*.java"],
@@ -23,16 +43,38 @@ java_library {
     sdk_version: "system_current",
 }
 
+// Common defaults to define SDK level
 java_defaults {
-    name: "NetworkStackCommon",
+    name: "NetworkStackApiCurrentLevel",
     sdk_version: "system_current",
     min_sdk_version: "28",
 }
 
-// Library including the network stack, used to compile both variants of the network stack
-android_library {
-    name: "NetworkStackBase",
-    defaults: ["NetworkStackCommon"],
+java_defaults {
+    name: "NetworkStackApiStableLevel",
+    sdk_version: "system_current", // TODO: change to system_29
+    min_sdk_version: "28",
+}
+
+// Java libraries for the API shims
+filegroup {
+    name: "NetworkStackApiCurrentShims",
+    srcs: [
+        "apishim/current/**/*.java"
+    ],
+}
+
+filegroup {
+    name: "NetworkStackApiStableShims",
+    srcs: [
+        "apishim/29/**/*.java"
+    ],
+}
+
+// Common defaults for android libraries containing network stack code, used to compile variants of
+// the network stack in the system process and in the network_stack process
+java_defaults {
+    name: "NetworkStackAndroidLibraryDefaults",
     srcs: [
         "src/**/*.java",
         ":framework-networkstack-shared-srcs",
@@ -51,43 +93,27 @@ android_library {
     manifest: "AndroidManifestBase.xml",
 }
 
-cc_library_shared {
-    name: "libnetworkstackutilsjni",
+// The versions of the android library containing network stack code compiled for each SDK variant
+android_library {
+    name: "NetworkStackApiCurrentLib",
+    defaults: ["NetworkStackApiCurrentLevel", "NetworkStackAndroidLibraryDefaults"],
     srcs: [
-        "jni/network_stack_utils_jni.cpp"
-    ],
-    sdk_version: "current",
-    shared_libs: [
-        "liblog",
-        "libnativehelper_compat_libc++",
+        ":NetworkStackApiCurrentShims",
     ],
+}
 
-    // We cannot use plain "libc++" here to link libc++ dynamically because it results in:
-    //   java.lang.UnsatisfiedLinkError: dlopen failed: library "libc++_shared.so" not found
-    // even if "libc++" is added into jni_libs below. Adding "libc++_shared" into jni_libs doesn't
-    // build because soong complains of:
-    //   module NetworkStack missing dependencies: libc++_shared
-    //
-    // So, link libc++ statically. This means that we also need to ensure that all the C++ libraries
-    // we depend on do not dynamically link libc++. This is currently the case, because liblog is
-    // C-only and libnativehelper_compat_libc also uses stl: "c++_static".
-    //
-    // TODO: find a better solution for this in R.
-    stl: "c++_static",
-    cflags: [
-        "-Wall",
-        "-Werror",
-        "-Wno-unused-parameter",
+android_library {
+    name: "NetworkStackApiStableLib",
+    defaults: ["NetworkStackApiStableLevel", "NetworkStackAndroidLibraryDefaults"],
+    srcs: [
+        ":NetworkStackApiStableShims",
     ],
 }
 
+// Common defaults for compiling the actual APK, based on the NetworkStackApiXBase android libraries
 java_defaults {
-    name: "NetworkStackAppCommon",
-    defaults: ["NetworkStackCommon"],
+    name: "NetworkStackAppDefaults",
     privileged: true,
-    static_libs: [
-        "NetworkStackBase",
-    ],
     jni_libs: [
         "libnativehelper_compat_libc++",
         "libnetworkstackutilsjni",
@@ -95,6 +121,7 @@ java_defaults {
     // Resources already included in NetworkStackBase
     resource_dirs: [],
     jarjar_rules: "jarjar-rules-shared.txt",
+    use_embedded_native_libs: true,
     optimize: {
         proguard_flags_files: ["proguard.flags"],
     },
@@ -103,7 +130,8 @@ java_defaults {
 // Non-updatable network stack running in the system server process for devices not using the module
 android_app {
     name: "InProcessNetworkStack",
-    defaults: ["NetworkStackAppCommon"],
+    defaults: [ "NetworkStackAppDefaults", "NetworkStackApiCurrentLevel"],
+    static_libs: ["NetworkStackApiCurrentLib"],
     certificate: "platform",
     manifest: "AndroidManifest_InProcess.xml",
     // InProcessNetworkStack is a replacement for NetworkStack
@@ -117,20 +145,63 @@ android_app {
 // Updatable network stack packaged as an application
 android_app {
     name: "NetworkStack",
-    defaults: ["NetworkStackAppCommon"],
+    defaults: ["NetworkStackAppDefaults", "NetworkStackApiCurrentLevel"],
+    static_libs: ["NetworkStackApiCurrentLib"],
+    certificate: "networkstack",
+    manifest: "AndroidManifest.xml",
+    // The permission configuration *must* be included to ensure security of the device
+    required: ["NetworkPermissionConfig"],
+}
+
+// Updatable network stack for finalized API
+android_app {
+    name: "NetworkStackApiStable",
+    defaults: ["NetworkStackAppDefaults", "NetworkStackApiStableLevel"],
+    static_libs: ["NetworkStackApiStableLib"],
     certificate: "networkstack",
     manifest: "AndroidManifest.xml",
-    use_embedded_native_libs: true,
     // The permission configuration *must* be included to ensure security of the device
     required: ["NetworkPermissionConfig"],
 }
 
+// Android library to derive test APKs for integration tests
 android_library {
     name: "TestNetworkStackLib",
-    defaults: ["NetworkStackAppCommon"],
+    defaults: ["NetworkStackAppDefaults", "NetworkStackApiCurrentLevel"],
+    static_libs: ["NetworkStackApiCurrentLib"],
     manifest: "AndroidManifest.xml",
 }
 
+cc_library_shared {
+    name: "libnetworkstackutilsjni",
+    srcs: [
+        "jni/network_stack_utils_jni.cpp"
+    ],
+    sdk_version: "current",
+    shared_libs: [
+        "liblog",
+        "libnativehelper_compat_libc++",
+    ],
+
+    // We cannot use plain "libc++" here to link libc++ dynamically because it results in:
+    //   java.lang.UnsatisfiedLinkError: dlopen failed: library "libc++_shared.so" not found
+    // even if "libc++" is added into jni_libs below. Adding "libc++_shared" into jni_libs doesn't
+    // build because soong complains of:
+    //   module NetworkStack missing dependencies: libc++_shared
+    //
+    // So, link libc++ statically. This means that we also need to ensure that all the C++ libraries
+    // we depend on do not dynamically link libc++. This is currently the case, because liblog is
+    // C-only and libnativehelper_compat_libc also uses stl: "c++_static".
+    //
+    // TODO: find a better solution for this in R.
+    stl: "c++_static",
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wno-unused-parameter",
+    ],
+}
+
 genrule {
     name: "statslog-networkstack-java-gen",
     tools: ["stats-log-api-gen"],
@@ -148,11 +219,10 @@ genrule {
 
 android_app {
     name: "TestNetworkStack",
-    defaults: ["NetworkStackAppCommon"],
+    defaults: ["NetworkStackAppDefaults", "NetworkStackApiCurrentLevel"],
+    static_libs: ["NetworkStackApiCurrentLib"],
     certificate: "networkstack",
     manifest: ":NetworkStackTestAndroidManifest",
-    use_embedded_native_libs: true,
     // The permission configuration *must* be included to ensure security of the device
     required: ["NetworkPermissionConfig"],
 }
-
diff --git a/apishim/29/com/android/networkstack/apishim/SocketUtilsShimImpl.java b/apishim/29/com/android/networkstack/apishim/SocketUtilsShimImpl.java
new file mode 100644
index 0000000..0e41e19
--- /dev/null
+++ b/apishim/29/com/android/networkstack/apishim/SocketUtilsShimImpl.java
@@ -0,0 +1,36 @@
+/*
+ * 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.networkstack.apishim;
+
+import android.net.util.SocketUtils;
+
+import androidx.annotation.NonNull;
+
+import java.net.SocketAddress;
+
+/**
+ * Implementation of SocketUtilsShim for API 29.
+ */
+public class SocketUtilsShimImpl implements SocketUtilsShim {
+    @NonNull
+    @Override
+    public SocketAddress makePacketSocketAddress(
+            int protocol, int ifIndex, @NonNull byte[] hwAddr) {
+        // Not available for API <= 29: fallback to older behavior.
+        return SocketUtils.makePacketSocketAddress(ifIndex, hwAddr);
+    }
+}
diff --git a/apishim/current/com/android/networkstack/apishim/SocketUtilsShimImpl.java b/apishim/current/com/android/networkstack/apishim/SocketUtilsShimImpl.java
new file mode 100644
index 0000000..92f8438
--- /dev/null
+++ b/apishim/current/com/android/networkstack/apishim/SocketUtilsShimImpl.java
@@ -0,0 +1,36 @@
+/*
+ * 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.networkstack.apishim;
+
+import android.net.util.SocketUtils;
+
+import androidx.annotation.NonNull;
+
+import java.net.SocketAddress;
+
+/**
+ * Implementation of {@link SocketUtilsShim} for API 30.
+ */
+public class SocketUtilsShimImpl implements SocketUtilsShim {
+    @NonNull
+    @Override
+    public SocketAddress makePacketSocketAddress(
+            int protocol, int ifIndex, @NonNull byte[] hwAddr) {
+        // TODO: use new API (which takes protocol, ifIndex, hwAddr) once implemented
+        return SocketUtils.makePacketSocketAddress(ifIndex, hwAddr);
+    }
+}
diff --git a/src/com/android/networkstack/apishim/SocketUtilsShim.java b/src/com/android/networkstack/apishim/SocketUtilsShim.java
new file mode 100644
index 0000000..34b5f40
--- /dev/null
+++ b/src/com/android/networkstack/apishim/SocketUtilsShim.java
@@ -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.networkstack.apishim;
+
+import androidx.annotation.NonNull;
+
+import java.net.SocketAddress;
+
+/**
+ * Interface used to access API methods in {@link android.net.util.SocketUtils}, with appropriate
+ * fallbacks if the methods are not yet part of the released API.
+ *
+ * <p>This interface makes it easier for callers to use SocketUtilsShimImpl, as it's more obvious
+ * what methods must be implemented on each API level, and it abstracts from callers the need to
+ * reference classes that have different implementations (which also does not work well with IDEs).
+ */
+public interface SocketUtilsShim {
+    /**
+     * Create a new instance of SocketUtilsShim.
+     */
+    @NonNull
+    static SocketUtilsShim newInstance() {
+        // TODO: when the R API is finalized, rename the API 29 shim to SocketUtilsCompat, and
+        // return it here instead of SocketUtilsShimImpl for devices with Build.VERSION <= 29.
+        // For now, the switch between implementations is done at build time (swapping the java file
+        // with another), since production modules should not be built with a non-finalized API.
+        return new SocketUtilsShimImpl();
+    }
+
+    /**
+     * @see android.net.util.SocketUtils#makePacketSocketAddress(int, int, byte[])
+     */
+    @NonNull
+    SocketAddress makePacketSocketAddress(int protocol, int ifIndex, @NonNull byte[] hwAddr);
+}
diff --git a/tests/integration/Android.bp b/tests/integration/Android.bp
index ec16467..89b3968 100644
--- a/tests/integration/Android.bp
+++ b/tests/integration/Android.bp
@@ -24,7 +24,7 @@ android_test {
         "androidx.test.rules",
         "mockito-target-extended-minus-junit4",
         "net-tests-utils",
-        "NetworkStackBase",
+        "NetworkStackApiCurrentLib",
         "testables",
     ],
     libs: [
diff --git a/tests/unit/Android.bp b/tests/unit/Android.bp
index 9c1c791..3081666 100644
--- a/tests/unit/Android.bp
+++ b/tests/unit/Android.bp
@@ -24,7 +24,7 @@ android_test {
         "androidx.test.rules",
         "mockito-target-extended-minus-junit4",
         "net-tests-utils",
-        "NetworkStackBase",
+        "NetworkStackApiCurrentLib",
         "testables",
     ],
     libs: [