Nat464Xlat.java revision 43b76dfddbfe2a27a0658dbca8632a9b1dc8d6ff 
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        // If this is a runtime restart, it's possible that clatd is already
79        // running, but we don't know about it. If so, stop it.
80        try {
81            if (mNMService.isClatdStarted()) {
82                mNMService.stopClatd();
83            }
84        } catch(RemoteException e) {}  // Well, we tried.
85    }
86
87    /**
88     * Determines whether a network requires clat.
89     * @param network the NetworkAgentInfo corresponding to the network.
90     * @return true if the network requires clat, false otherwise.
91     */
92    public boolean requiresClat(NetworkAgentInfo network) {
93        int netType = network.networkInfo.getType();
94        LinkProperties lp = network.linkProperties;
95        // Only support clat on mobile for now.
96        Slog.d(TAG, "requiresClat: netType=" + netType + ", hasIPv4Address=" +
97               lp.hasIPv4Address());
98        return netType == TYPE_MOBILE && !lp.hasIPv4Address();
99    }
100
101    public static boolean isRunningClat(LinkProperties lp) {
102      return lp != null && lp.getAllInterfaceNames().contains(CLAT_INTERFACE_NAME);
103    }
104
105    /**
106     * Starts the clat daemon.
107     * @param lp The link properties of the interface to start clatd on.
108     */
109    public void startClat(NetworkAgentInfo network) {
110        if (mNetworkMessenger != null && mNetworkMessenger != network.messenger) {
111            Slog.e(TAG, "startClat: too many networks requesting clat");
112            return;
113        }
114        mNetworkMessenger = network.messenger;
115        LinkProperties lp = network.linkProperties;
116        mBaseLP = new LinkProperties(lp);
117        if (mIsStarted) {
118            Slog.e(TAG, "startClat: already started");
119            return;
120        }
121        String iface = lp.getInterfaceName();
122        Slog.i(TAG, "Starting clatd on " + iface + ", lp=" + lp);
123        try {
124            mNMService.startClatd(iface);
125        } catch(RemoteException e) {
126            Slog.e(TAG, "Error starting clat daemon: " + e);
127        }
128        mIsStarted = true;
129    }
130
131    /**
132     * Stops the clat daemon.
133     */
134    public void stopClat() {
135        if (mIsStarted) {
136            Slog.i(TAG, "Stopping clatd");
137            try {
138                mNMService.stopClatd();
139            } catch(RemoteException e) {
140                Slog.e(TAG, "Error stopping clat daemon: " + e);
141            }
142            mIsStarted = false;
143            mIsRunning = false;
144            mNetworkMessenger = null;
145            mBaseLP = null;
146            mLP.clear();
147        } else {
148            Slog.e(TAG, "stopClat: already stopped");
149        }
150    }
151
152    public boolean isStarted() {
153        return mIsStarted;
154    }
155
156    public boolean isRunning() {
157        return mIsRunning;
158    }
159
160    private void updateConnectivityService() {
161        Message msg = mHandler.obtainMessage(
162            NetworkAgent.EVENT_NETWORK_PROPERTIES_CHANGED, mBaseLP);
163        msg.replyTo = mNetworkMessenger;
164        Slog.i(TAG, "sending message to ConnectivityService: " + msg);
165        msg.sendToTarget();
166    }
167
168    @Override
169    public void interfaceAdded(String iface) {
170        if (iface.equals(CLAT_INTERFACE_NAME)) {
171            Slog.i(TAG, "interface " + CLAT_INTERFACE_NAME +
172                   " added, mIsRunning = " + mIsRunning + " -> true");
173            mIsRunning = true;
174
175            // Create the LinkProperties for the clat interface by fetching the
176            // IPv4 address for the interface and adding an IPv4 default route,
177            // then stack the LinkProperties on top of the link it's running on.
178            // Although the clat interface is a point-to-point tunnel, we don't
179            // point the route directly at the interface because some apps don't
180            // understand routes without gateways (see, e.g., http://b/9597256
181            // http://b/9597516). Instead, set the next hop of the route to the
182            // clat IPv4 address itself (for those apps, it doesn't matter what
183            // the IP of the gateway is, only that there is one).
184            try {
185                InterfaceConfiguration config = mNMService.getInterfaceConfig(iface);
186                LinkAddress clatAddress = config.getLinkAddress();
187                mLP.clear();
188                mLP.setInterfaceName(iface);
189                RouteInfo ipv4Default = new RouteInfo(new LinkAddress(Inet4Address.ANY, 0),
190                                                      clatAddress.getAddress(), iface);
191                mLP.addRoute(ipv4Default);
192                mLP.addLinkAddress(clatAddress);
193                mBaseLP.addStackedLink(mLP);
194                Slog.i(TAG, "Adding stacked link. tracker LP: " + mBaseLP);
195                updateConnectivityService();
196            } catch(RemoteException e) {
197                Slog.e(TAG, "Error getting link properties: " + e);
198            }
199        }
200    }
201
202    @Override
203    public void interfaceRemoved(String iface) {
204        if (iface == CLAT_INTERFACE_NAME) {
205            if (mIsRunning) {
206                NetworkUtils.resetConnections(
207                    CLAT_INTERFACE_NAME,
208                    NetworkUtils.RESET_IPV4_ADDRESSES);
209                mBaseLP.removeStackedLink(mLP);
210                updateConnectivityService();
211            }
212            Slog.i(TAG, "interface " + CLAT_INTERFACE_NAME +
213                   " removed, mIsRunning = " + mIsRunning + " -> false");
214            mIsRunning = false;
215            mLP.clear();
216            Slog.i(TAG, "mLP = " + mLP);
217        }
218    }
219};
220