Merge "Move netlink updates to a new NetlinkTracker class."

core/java/com/android/server/net/NetlinkTracker.java

@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2014 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.server.net;
+
+import android.net.LinkAddress;
+import android.net.LinkProperties;
+import android.util.Log;
+
+/**
+ * Keeps track of link configuration received from Netlink.
+ *
+ * Instances of this class are expected to be owned by subsystems such as Wi-Fi
+ * or Ethernet that manage one or more network interfaces. Each interface to be
+ * tracked needs its own {@code NetlinkTracker}.
+ *
+ * An instance of this class is constructed by passing in an interface name and
+ * a callback. The owner is then responsible for registering the tracker with
+ * NetworkManagementService. When the class receives update notifications from
+ * the NetworkManagementService notification threads, it applies the update to
+ * its local LinkProperties, and if something has changed, notifies its owner of
+ * the update via the callback.
+ *
+ * The owner can then call {@code getLinkProperties()} in order to find out
+ * what changed. If in the meantime the LinkProperties stored here have changed,
+ * this class will return the current LinkProperties. Because each change
+ * triggers an update callback after the change is made, the owner may get more
+ * callbacks than strictly necessary (some of which may be no-ops), but will not
+ * be out of sync once all callbacks have been processed.
+ *
+ * Threading model:
+ *
+ * - The owner of this class is expected to create it, register it, and call
+ *   getLinkProperties or clearLinkProperties on its thread.
+ * - Most of the methods in the class are inherited from BaseNetworkObserver
+ *   and are called by NetworkManagementService notification threads.
+ * - All accesses to mLinkProperties must be synchronized(this). All the other
+ *   member variables are immutable once the object is constructed.
+ *
+ * This class currently tracks IPv4 and IPv6 addresses. In the future it will
+ * track routes and DNS servers.
+ *
+ * @hide
+ */
+public class NetlinkTracker extends BaseNetworkObserver {
+
+    private final String TAG;
+
+    public interface Callback {
+        public void update();
+    }
+
+    private final String mInterfaceName;
+    private final Callback mCallback;
+    private final LinkProperties mLinkProperties;
+
+    private static final boolean DBG = true;
+
+    public NetlinkTracker(String iface, Callback callback) {
+        TAG = "NetlinkTracker/" + iface;
+        mInterfaceName = iface;
+        mCallback = callback;
+        mLinkProperties = new LinkProperties();
+        mLinkProperties.setInterfaceName(mInterfaceName);
+    }
+
+    private void maybeLog(String operation, String iface, LinkAddress address) {
+        if (DBG) {
+            Log.d(TAG, operation + ": " + address + " on " + iface +
+                    " flags " + address.getFlags() + " scope " + address.getScope());
+        }
+    }
+
+    @Override
+    public void addressUpdated(String iface, LinkAddress address) {
+        if (mInterfaceName.equals(iface)) {
+            maybeLog("addressUpdated", iface, address);
+            boolean changed;
+            synchronized (this) {
+                changed = mLinkProperties.addLinkAddress(address);
+            }
+            if (changed) {
+                mCallback.update();
+            }
+        }
+    }
+
+    @Override
+    public void addressRemoved(String iface, LinkAddress address) {
+        if (mInterfaceName.equals(iface)) {
+            maybeLog("addressRemoved", iface, address);
+            boolean changed;
+            synchronized (this) {
+                changed = mLinkProperties.removeLinkAddress(address);
+            }
+            if (changed) {
+                mCallback.update();
+            }
+        }
+    }
+
+    /**
+     * Returns a copy of this object's LinkProperties.
+     */
+    public synchronized LinkProperties getLinkProperties() {
+        return new LinkProperties(mLinkProperties);
+    }
+
+    public synchronized void clearLinkProperties() {
+        mLinkProperties.clear();
+        mLinkProperties.setInterfaceName(mInterfaceName);
+    }
+}