Move BpfUtils -- add java class

Adding a TcUtils java class.

Bug: 202086915
Bug: 157552970
Test: atest TetheringTests
Change-Id: Ifb97d822bd96de6ed1a3fed547234ef32d691ad8

staticlibs/Android.bp

@@ -112,6 +112,7 @@ java_library {
     srcs: [
         "device/com/android/net/module/util/BpfMap.java",
         "device/com/android/net/module/util/JniUtil.java",
+        "device/com/android/net/module/util/TcUtils.java",
     ],
     sdk_version: "system_current",
     min_sdk_version: "29",

staticlibs/device/com/android/net/module/util/TcUtils.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2022 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.net.module.util;
+
+import java.io.IOException;
+
+/**
+ * Contains mostly tc-related functionality.
+ */
+public class TcUtils {
+    /**
+     * Checks if the network interface uses an ethernet L2 header.
+     *
+     * @param iface the network interface.
+     * @return true if the interface uses an ethernet L2 header.
+     * @throws IOException
+     */
+    public static native boolean isEthernet(String iface) throws IOException;
+
+    /**
+     * Attach a tc bpf filter.
+     *
+     * Equivalent to the following 'tc' command:
+     * tc filter add dev .. in/egress prio .. protocol ipv6/ip bpf object-pinned
+     * /sys/fs/bpf/... direct-action
+     *
+     * @param ifIndex the network interface index.
+     * @param ingress ingress or egress qdisc.
+     * @param prio
+     * @param proto
+     * @param bpfProgPath
+     * @throws IOException
+     */
+    public static native void tcFilterAddDevBpf(int ifIndex, boolean ingress, short prio,
+            short proto, String bpfProgPath) throws IOException;
+
+    /**
+     * Delete a tc filter.
+     *
+     * Equivalent to the following 'tc' command:
+     * tc filter del dev .. in/egress prio .. protocol ..
+     *
+     * @param ifIndex the network interface index.
+     * @param ingress ingress or egress qdisc.
+     * @param prio the filter preference.
+     * @param proto protocol.
+     * @throws IOException
+     */
+    public static native void tcFilterDelDev(int ifIndex, boolean ingress, short prio,
+            short proto) throws IOException;
+}