Nat464Xlat.java revision 3b75982e39ed9370153ae7f238f1d6041b9506ed 
1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.server.connectivity;
18
19import static android.net.ConnectivityManager.TYPE_MOBILE;
20
21import java.net.Inet4Address;
22
23import android.content.Context;
24import android.net.IConnectivityManager;
25import android.net.InterfaceConfiguration;
26import android.net.LinkAddress;
27import android.net.LinkProperties;
28import android.net.NetworkAgent;
29import android.net.NetworkUtils;
30import android.net.RouteInfo;
31import android.os.Handler;
32import android.os.Message;
33import android.os.Messenger;
34import android.os.INetworkManagementService;
35import android.os.RemoteException;
36import android.util.Slog;
37
38import com.android.server.net.BaseNetworkObserver;
39
40/**
41 * @hide
42 *
43 * Class to manage a 464xlat CLAT daemon.
44 */
45public class Nat464Xlat extends BaseNetworkObserver {
46    private Context mContext;
47    private INetworkManagementService mNMService;
48    private IConnectivityManager mConnService;
49    // Whether we started clatd and expect it to be running.
50    private boolean mIsStarted;
51    // Whether the clatd interface exists (i.e., clatd is running).
52    private boolean mIsRunning;
53    // The LinkProperties of the clat interface.
54    private LinkProperties mLP;
55    // Current LinkProperties of the network.  Includes mLP as a stacked link when clat is active.
56    private LinkProperties mBaseLP;
57    // ConnectivityService Handler for LinkProperties updates.
58    private Handler mHandler;
59    // Marker to connote which network we're augmenting.
60    private Messenger mNetworkMessenger;
61
62    // This must match the interface name in clatd.conf.
63    private static final String CLAT_INTERFACE_NAME = "clat4";
64
65    private static final String TAG = "Nat464Xlat";
66
67    public Nat464Xlat(Context context, INetworkManagementService nmService,
68                      IConnectivityManager connService, Handler handler) {
69        mContext = context;
70        mNMService = nmService;
71        mConnService = connService;
72        mHandler = handler;
73
74        mIsStarted = false;
75        mIsRunning = false;
76        mLP = new LinkProperties();
77    }
78
79    /**
80     * Determines whether a network requires clat.
81     * @param network the NetworkAgentInfo corresponding to the network.
82     * @return true if the network requires clat, false otherwise.
83     */
84    public boolean requiresClat(NetworkAgentInfo network) {
85        int netType = network.networkInfo.getType();
86        LinkProperties lp = network.linkProperties;
87        // Only support clat on mobile for now.
88        Slog.d(TAG, "requiresClat: netType=" + netType + ", hasIPv4Address=" +
89               lp.hasIPv4Address());
90        return netType == TYPE_MOBILE && !lp.hasIPv4Address();
91    }
92
93    public static boolean isRunningClat(LinkProperties lp) {
94      return lp != null && lp.getAllInterfaceNames().contains(CLAT_INTERFACE_NAME);
95    }
96
97    /**
98     * Starts the clat daemon.
99     * @param lp The link properties of the interface to start clatd on.
100     */
101    public void startClat(NetworkAgentInfo network) {
102        if (mNetworkMessenger != null && mNetworkMessenger != network.messenger) {
103            Slog.e(TAG, "startClat: too many networks requesting clat");
104            return;
105        }
106        mNetworkMessenger = network.messenger;
107        LinkProperties lp = network.linkProperties;
108        mBaseLP = new LinkProperties(lp);
109        if (mIsStarted) {
110            Slog.e(TAG, "startClat: already started");
111            return;
112        }
113        String iface = lp.getInterfaceName();
114        Slog.i(TAG, "Starting clatd on " + iface + ", lp=" + lp);
115        try {
116            mNMService.startClatd(iface);
117        } catch(RemoteException e) {
118            Slog.e(TAG, "Error starting clat daemon: " + e);
119        }
120        mIsStarted = true;
121    }
122
123    /**
124     * Stops the clat daemon.
125     */
126    public void stopClat() {
127        if (mIsStarted) {
128            Slog.i(TAG, "Stopping clatd");
129            try {
130                mNMService.stopClatd();
131            } catch(RemoteException e) {
132                Slog.e(TAG, "Error stopping clat daemon: " + e);
133            }
134            mIsStarted = false;
135            mIsRunning = false;
136            mNetworkMessenger = null;
137            mBaseLP = null;
138            mLP.clear();
139        } else {
140            Slog.e(TAG, "stopClat: already stopped");
141        }
142    }
143
144    public boolean isStarted() {
145        return mIsStarted;
146    }
147
148    public boolean isRunning() {
149        return mIsRunning;
150    }
151
152    private void updateConnectivityService() {
153        Message msg = mHandler.obtainMessage(
154            NetworkAgent.EVENT_NETWORK_PROPERTIES_CHANGED, mBaseLP);
155        msg.replyTo = mNetworkMessenger;
156        Slog.i(TAG, "sending message to ConnectivityService: " + msg);
157        msg.sendToTarget();
158    }
159
160    @Override
161    public void interfaceAdded(String iface) {
162        if (iface.equals(CLAT_INTERFACE_NAME)) {
163            Slog.i(TAG, "interface " + CLAT_INTERFACE_NAME +
164                   " added, mIsRunning = " + mIsRunning + " -> true");
165            mIsRunning = true;
166
167            // Create the LinkProperties for the clat interface by fetching the
168            // IPv4 address for the interface and adding an IPv4 default route,
169            // then stack the LinkProperties on top of the link it's running on.
170            // Although the clat interface is a point-to-point tunnel, we don't
171            // point the route directly at the interface because some apps don't
172            // understand routes without gateways (see, e.g., http://b/9597256
173            // http://b/9597516). Instead, set the next hop of the route to the
174            // clat IPv4 address itself (for those apps, it doesn't matter what
175            // the IP of the gateway is, only that there is one).
176            try {
177                InterfaceConfiguration config = mNMService.getInterfaceConfig(iface);
178                LinkAddress clatAddress = config.getLinkAddress();
179                mLP.clear();
180                mLP.setInterfaceName(iface);
181                RouteInfo ipv4Default = new RouteInfo(new LinkAddress(Inet4Address.ANY, 0),
182                                                      clatAddress.getAddress(), iface);
183                mLP.addRoute(ipv4Default);
184                mLP.addLinkAddress(clatAddress);
185                mBaseLP.addStackedLink(mLP);
186                Slog.i(TAG, "Adding stacked link. tracker LP: " + mBaseLP);
187                updateConnectivityService();
188            } catch(RemoteException e) {
189                Slog.e(TAG, "Error getting link properties: " + e);
190            }
191        }
192    }
193
194    @Override
195    public void interfaceRemoved(String iface) {
196        if (iface == CLAT_INTERFACE_NAME) {
197            if (mIsRunning) {
198                NetworkUtils.resetConnections(
199                    CLAT_INTERFACE_NAME,
200                    NetworkUtils.RESET_IPV4_ADDRESSES);
201            }
202            Slog.i(TAG, "interface " + CLAT_INTERFACE_NAME +
203                   " removed, mIsRunning = " + mIsRunning + " -> false");
204            mIsRunning = false;
205            mBaseLP.removeStackedLink(mLP);
206            mLP.clear();
207            updateConnectivityService();
208            Slog.i(TAG, "mLP = " + mLP);
209        }
210    }
211};
212