Change tetheroffloadjni to tetheringutilsjni

Rename tetheroffloadjni to tetheringutilsjni and move setupRaSocket
jni method from NetUtils into tetheringutilsjni.

Bug: 143195885
Test: -build, flash, boot
      -atest TetheringTests
      -Off/On hotspot with ipv6 upstream

Change-Id: Ib68eb6999bbe2d3ca97e68712f22b105311ef800

Tethering/src/android/net/util/TetheringUtils.java

@@ -0,0 +1,42 @@
+/*
+ * 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 android.net.util;
+
+import java.io.FileDescriptor;
+import java.net.SocketException;
+
+/**
+ * Native methods for tethering utilization.
+ *
+ * {@hide}
+ */
+public class TetheringUtils {
+
+    /**
+     * Offload management process need to know conntrack rules to support NAT, but it may not have
+     * permission to create netlink netfilter sockets. Create two netlink netfilter sockets and
+     * share them with offload management process.
+     */
+    public static native boolean configOffload();
+
+    /**
+     * Configures a socket for receiving ICMPv6 router solicitations and sending advertisements.
+     * @param fd the socket's {@link FileDescriptor}.
+     * @param ifIndex the interface index.
+     */
+    public static native void setupRaSocket(FileDescriptor fd, int ifIndex)
+            throws SocketException;
+}