Have a collection of utilities for netd - NetdUtils

Some files which will be inside mainline module depend on
NetworkManagementService to talk to netd, but after they become
a part of mainline module, they cannot access @hide API of
NetworkManagementService.
So create a NetdUtils to help them to talk to netd.

Bug: 170598012
Test: atest CtsNetTestCasesLatestSdk NetdStaticLibTests
Change-Id: I8bee1204b9533b70844da0b3768427438fd0c890

1 files changed, 105 insertions, 0 deletions

diff --git a/client-libs/netd/com/android/net/module/util/NetdUtils.java b/client-libs/netd/com/android/net/module/util/NetdUtils.java
new file mode 100644
index 00000000..1f319129
--- /dev/null
+++ b/client-libs/netd/com/android/net/module/util/NetdUtils.java
@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2021 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 static android.net.INetd.IF_STATE_DOWN;
+import static android.net.INetd.IF_STATE_UP;
+
+import android.net.INetd;
+import android.net.InterfaceConfigurationParcel;
+import android.os.RemoteException;
+import android.os.ServiceSpecificException;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.VisibleForTesting;
+
+import java.util.ArrayList;
+
+/**
+ * Collection of utilities for netd.
+ */
+public class NetdUtils {
+    /**
+     * Get InterfaceConfigurationParcel from netd.
+     */
+    public static InterfaceConfigurationParcel getInterfaceConfigParcel(@NonNull INetd netd,
+            @NonNull String iface) {
+        try {
+            return netd.interfaceGetCfg(iface);
+        } catch (RemoteException | ServiceSpecificException e) {
+            throw new IllegalStateException(e);
+        }
+    }
+
+    private static void validateFlag(String flag) {
+        if (flag.indexOf(' ') >= 0) {
+            throw new IllegalArgumentException("flag contains space: " + flag);
+        }
+    }
+
+    @VisibleForTesting
+    protected static String[] removeAndAddFlags(@NonNull String[] flags, @NonNull String remove,
+            @NonNull String add) {
+        final ArrayList<String> result = new ArrayList<>();
+        try {
+            // Validate the add flag first, so that the for-loop can be ignore once the format of
+            // add flag is invalid.
+            validateFlag(add);
+            for (String flag : flags) {
+                // Simply ignore both of remove and add flags first, then add the add flag after
+                // exiting the loop to prevent adding the duplicate flag.
+                if (remove.equals(flag) || add.equals(flag)) continue;
+                result.add(flag);
+            }
+            result.add(add);
+            return result.toArray(new String[result.size()]);
+        } catch (IllegalArgumentException iae) {
+            throw new IllegalStateException("Invalid InterfaceConfigurationParcel", iae);
+        }
+    }
+
+    /**
+     * Set interface configuration to netd by passing InterfaceConfigurationParcel.
+     */
+    public static void setInterfaceConfig(INetd netd, InterfaceConfigurationParcel configParcel) {
+        try {
+            netd.interfaceSetCfg(configParcel);
+        } catch (RemoteException | ServiceSpecificException e) {
+            throw new IllegalStateException(e);
+        }
+    }
+
+    /**
+     * Set the given interface up.
+     */
+    public static void setInterfaceUp(INetd netd, String iface) {
+        final InterfaceConfigurationParcel configParcel = getInterfaceConfigParcel(netd, iface);
+        configParcel.flags = removeAndAddFlags(configParcel.flags, IF_STATE_DOWN /* remove */,
+                IF_STATE_UP /* add */);
+        setInterfaceConfig(netd, configParcel);
+    }
+
+    /**
+     * Set the given interface down.
+     */
+    public static void setInterfaceDown(INetd netd, String iface) {
+        final InterfaceConfigurationParcel configParcel = getInterfaceConfigParcel(netd, iface);
+        configParcel.flags = removeAndAddFlags(configParcel.flags, IF_STATE_UP /* remove */,
+                IF_STATE_DOWN /* add */);
+        setInterfaceConfig(netd, configParcel);
+    }
+}