Nat464Xlat.java revision 1df5fa55c5a5c1ba054b783ea639c99d57c357cf 
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 static boolean requiresClat(NetworkAgentInfo nai) {
93        final int netType = nai.networkInfo.getType();
94        final boolean connected = nai.networkInfo.isConnected();
95        final boolean hasIPv4Address =
96                (nai.linkProperties != null) ? nai.linkProperties.hasIPv4Address() : false;
97        Slog.d(TAG, "requiresClat: netType=" + netType +
98                    ", connected=" + connected +
99                    ", hasIPv4Address=" + hasIPv4Address);
100        // Only support clat on mobile for now.
101        return netType == TYPE_MOBILE && connected && !hasIPv4Address;
102    }
103
104    public boolean isRunningClat(NetworkAgentInfo network) {
105        return mNetworkMessenger == network.messenger;
106    }
107
108    /**
109     * Starts the clat daemon.
110     * @param lp The link properties of the interface to start clatd on.
111     */
112    public void startClat(NetworkAgentInfo network) {
113        if (mNetworkMessenger != null && mNetworkMessenger != network.messenger) {
114            Slog.e(TAG, "startClat: too many networks requesting clat");
115            return;
116        }
117        mNetworkMessenger = network.messenger;
118        LinkProperties lp = network.linkProperties;
119        mBaseLP = new LinkProperties(lp);
120        if (mIsStarted) {
121            Slog.e(TAG, "startClat: already started");
122            return;
123        }
124        String iface = lp.getInterfaceName();
125        Slog.i(TAG, "Starting clatd on " + iface + ", lp=" + lp);
126        try {
127            mNMService.startClatd(iface);
128        } catch(RemoteException e) {
129            Slog.e(TAG, "Error starting clat daemon: " + e);
130        }
131        mIsStarted = true;
132    }
133
134    /**
135     * Stops the clat daemon.
136     */
137    public void stopClat() {
138        if (mIsStarted) {
139            Slog.i(TAG, "Stopping clatd");
140            try {
141                mNMService.stopClatd();
142            } catch(RemoteException e) {
143                Slog.e(TAG, "Error stopping clat daemon: " + e);
144            }
145            mIsStarted = false;
146            mIsRunning = false;
147            mNetworkMessenger = null;
148            mBaseLP = null;
149            mLP.clear();
150        } else {
151            Slog.e(TAG, "stopClat: already stopped");
152        }
153    }
154
155    private void updateConnectivityService() {
156        Message msg = mHandler.obtainMessage(
157            NetworkAgent.EVENT_NETWORK_PROPERTIES_CHANGED, mBaseLP);
158        msg.replyTo = mNetworkMessenger;
159        Slog.i(TAG, "sending message to ConnectivityService: " + msg);
160        msg.sendToTarget();
161    }
162
163    // Copies the stacked clat link in oldLp, if any, to the LinkProperties in nai.
164    public void fixupLinkProperties(NetworkAgentInfo nai, LinkProperties oldLp) {
165        if (isRunningClat(nai) &&
166                nai.linkProperties != null &&
167                !nai.linkProperties.getAllInterfaceNames().contains(CLAT_INTERFACE_NAME)) {
168            Slog.d(TAG, "clatd running, updating NAI for " + nai.linkProperties.getInterfaceName());
169            for (LinkProperties stacked: oldLp.getStackedLinks()) {
170                if (CLAT_INTERFACE_NAME.equals(stacked.getInterfaceName())) {
171                    nai.linkProperties.addStackedLink(stacked);
172                    break;
173                }
174            }
175        }
176    }
177
178    @Override
179    public void interfaceAdded(String iface) {
180        if (iface.equals(CLAT_INTERFACE_NAME)) {
181            Slog.i(TAG, "interface " + CLAT_INTERFACE_NAME +
182                   " added, mIsRunning = " + mIsRunning + " -> true");
183            mIsRunning = true;
184
185            // Create the LinkProperties for the clat interface by fetching the
186            // IPv4 address for the interface and adding an IPv4 default route,
187            // then stack the LinkProperties on top of the link it's running on.
188            try {
189                InterfaceConfiguration config = mNMService.getInterfaceConfig(iface);
190                LinkAddress clatAddress = config.getLinkAddress();
191                mLP.clear();
192                mLP.setInterfaceName(iface);
193
194                // Although the clat interface is a point-to-point tunnel, we don't
195                // point the route directly at the interface because some apps don't
196                // understand routes without gateways (see, e.g., http://b/9597256
197                // http://b/9597516). Instead, set the next hop of the route to the
198                // clat IPv4 address itself (for those apps, it doesn't matter what
199                // the IP of the gateway is, only that there is one).
200                RouteInfo ipv4Default = new RouteInfo(new LinkAddress(Inet4Address.ANY, 0),
201                                                      clatAddress.getAddress(), iface);
202                mLP.addRoute(ipv4Default);
203                mLP.addLinkAddress(clatAddress);
204                mBaseLP.addStackedLink(mLP);
205                Slog.i(TAG, "Adding stacked link. tracker LP: " + mBaseLP);
206                updateConnectivityService();
207            } catch(RemoteException e) {
208                Slog.e(TAG, "Error getting link properties: " + e);
209            }
210        }
211    }
212
213    @Override
214    public void interfaceRemoved(String iface) {
215        if (iface == CLAT_INTERFACE_NAME) {
216            if (mIsRunning) {
217                NetworkUtils.resetConnections(
218                    CLAT_INTERFACE_NAME,
219                    NetworkUtils.RESET_IPV4_ADDRESSES);
220                mBaseLP.removeStackedLink(mLP);
221                updateConnectivityService();
222            }
223            Slog.i(TAG, "interface " + CLAT_INTERFACE_NAME +
224                   " removed, mIsRunning = " + mIsRunning + " -> false");
225            mIsRunning = false;
226            mLP.clear();
227            Slog.i(TAG, "mLP = " + mLP);
228        }
229    }
230};
231