Move socket tagging implementation to mainline.

Currently, socket tagging is implemented in the framework. The
Java code is in NetworkManagmentSocketTagger.java and the JNI is
in libandroid and loaded by the general framework JNI loader.

- Move the Java implementation to TrafficStats, which is the only
  caller of NetworkManagmentSocketTagger. This simplifies the
  code a bit because a number of methods can be deleted.

- Move the JNI code to a new JNI library in the APEX. The library
  depends only on the NDK and statically links the NDK-only
  version of libnativehelper. Its size is only 5k on ARM and 10k
  on ARM64.

- Temporarily make the framework depend on this library until the
  rest of the T connectivity code moves to the APEX.

Test: atest NetworkUsageStatsTest CtsNetTestCases:TrafficStatsTest
Change-Id: I050c7c515237f68b78d08987bc443f50a7949c06

framework-t/src/android/net/TrafficStats.java

@@ -31,12 +31,9 @@ import android.media.MediaPlayer;
 import android.os.Binder;
 import android.os.Build;
 import android.os.RemoteException;
+import android.os.StrictMode;
 import android.util.Log;
 
-import com.android.server.NetworkManagementSocketTagger;
-
-import dalvik.system.SocketTagger;
-
 import java.io.FileDescriptor;
 import java.io.IOException;
 import java.net.DatagramSocket;
@@ -56,6 +53,10 @@ import java.net.SocketException;
  * use {@link NetworkStatsManager} instead.
  */
 public class TrafficStats {
+    static {
+        System.loadLibrary("framework-connectivity-tiramisu-jni");
+    }
+
     private static final String TAG = TrafficStats.class.getSimpleName();
     /**
      * The return value to indicate that the device does not support the statistic.
@@ -232,9 +233,68 @@ public class TrafficStats {
      */
     @SystemApi(client = MODULE_LIBRARIES)
     public static void attachSocketTagger() {
-        NetworkManagementSocketTagger.install();
+        dalvik.system.SocketTagger.set(new SocketTagger());
     }
 
+    private static class SocketTagger extends dalvik.system.SocketTagger {
+
+        // TODO: set to false
+        private static final boolean LOGD = true;
+
+        SocketTagger() {
+        }
+
+        @Override
+        public void tag(FileDescriptor fd) throws SocketException {
+            final UidTag tagInfo = sThreadUidTag.get();
+            if (LOGD) {
+                Log.d(TAG, "tagSocket(" + fd.getInt$() + ") with statsTag=0x"
+                        + Integer.toHexString(tagInfo.tag) + ", statsUid=" + tagInfo.uid);
+            }
+            if (tagInfo.tag == -1) {
+                StrictMode.noteUntaggedSocket();
+            }
+
+            if (tagInfo.tag == -1 && tagInfo.uid == -1) return;
+            final int errno = native_tagSocketFd(fd, tagInfo.tag, tagInfo.uid);
+            if (errno < 0) {
+                Log.i(TAG, "tagSocketFd(" + fd.getInt$() + ", "
+                        + tagInfo.tag + ", "
+                        + tagInfo.uid + ") failed with errno" + errno);
+            }
+        }
+
+        @Override
+        public void untag(FileDescriptor fd) throws SocketException {
+            if (LOGD) {
+                Log.i(TAG, "untagSocket(" + fd.getInt$() + ")");
+            }
+
+            final UidTag tagInfo = sThreadUidTag.get();
+            if (tagInfo.tag == -1 && tagInfo.uid == -1) return;
+
+            final int errno = native_untagSocketFd(fd);
+            if (errno < 0) {
+                Log.w(TAG, "untagSocket(" + fd.getInt$() + ") failed with errno " + errno);
+            }
+        }
+    }
+
+    private static native int native_tagSocketFd(FileDescriptor fd, int tag, int uid);
+    private static native int native_untagSocketFd(FileDescriptor fd);
+
+    private static class UidTag {
+        public int tag = -1;
+        public int uid = -1;
+    }
+
+    private static ThreadLocal<UidTag> sThreadUidTag = new ThreadLocal<UidTag>() {
+        @Override
+        protected UidTag initialValue() {
+            return new UidTag();
+        }
+    };
+
     /**
      * Set active tag to use when accounting {@link Socket} traffic originating
      * from the current thread. Only one active tag per thread is supported.
@@ -249,7 +309,7 @@ public class TrafficStats {
      * @see #clearThreadStatsTag()
      */
     public static void setThreadStatsTag(int tag) {
-        NetworkManagementSocketTagger.setThreadSocketStatsTag(tag);
+        getAndSetThreadStatsTag(tag);
     }
 
     /**
@@ -267,7 +327,9 @@ public class TrafficStats {
      *         restore any existing values after a nested operation is finished
      */
     public static int getAndSetThreadStatsTag(int tag) {
-        return NetworkManagementSocketTagger.setThreadSocketStatsTag(tag);
+        final int old = sThreadUidTag.get().tag;
+        sThreadUidTag.get().tag = tag;
+        return old;
     }
 
     /**
@@ -327,7 +389,7 @@ public class TrafficStats {
      * @see #setThreadStatsTag(int)
      */
     public static int getThreadStatsTag() {
-        return NetworkManagementSocketTagger.getThreadSocketStatsTag();
+        return sThreadUidTag.get().tag;
     }
 
     /**
@@ -337,7 +399,7 @@ public class TrafficStats {
      * @see #setThreadStatsTag(int)
      */
     public static void clearThreadStatsTag() {
-        NetworkManagementSocketTagger.setThreadSocketStatsTag(-1);
+        sThreadUidTag.get().tag = -1;
     }
 
     /**
@@ -357,7 +419,7 @@ public class TrafficStats {
      */
     @SuppressLint("RequiresPermission")
     public static void setThreadStatsUid(int uid) {
-        NetworkManagementSocketTagger.setThreadSocketStatsUid(uid);
+        sThreadUidTag.get().uid = uid;
     }
 
     /**
@@ -368,7 +430,7 @@ public class TrafficStats {
      * @see #setThreadStatsUid(int)
      */
     public static int getThreadStatsUid() {
-        return NetworkManagementSocketTagger.getThreadSocketStatsUid();
+        return sThreadUidTag.get().uid;
     }
 
     /**
@@ -395,7 +457,7 @@ public class TrafficStats {
      */
     @SuppressLint("RequiresPermission")
     public static void clearThreadStatsUid() {
-        NetworkManagementSocketTagger.setThreadSocketStatsUid(-1);
+        setThreadStatsUid(-1);
     }
 
     /**