Nat464Xlat.java revision 954394653dad05838235f48244a4320893e0f0cf
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 static final String TAG = "Nat464Xlat"; 47 48 // This must match the interface prefix in clatd.c. 49 private static final String CLAT_PREFIX = "v4-"; 50 51 private final INetworkManagementService mNMService; 52 53 // ConnectivityService Handler for LinkProperties updates. 54 private final Handler mHandler; 55 56 // The network we're running on. 57 private final NetworkAgentInfo mNetwork; 58 59 // Internal state variables. 60 // 61 // The possible states are: 62 // - Idle: start() not called. Everything is null. 63 // - Starting: start() called. Interfaces are non-null. isStarted() returns true. 64 // mIsRunning is false. 65 // - Running: start() called, and interfaceAdded() told us that mIface is up. Clat IP address 66 // is non-null. mIsRunning is true. 67 // 68 // Once mIface is non-null and isStarted() is true, methods called by ConnectivityService on 69 // its handler thread must not modify any internal state variables; they are only updated by the 70 // interface observers, called on the notification threads. 71 private String mBaseIface; 72 private String mIface; 73 private boolean mIsRunning; 74 75 public Nat464Xlat( 76 Context context, INetworkManagementService nmService, 77 Handler handler, NetworkAgentInfo nai) { 78 mNMService = nmService; 79 mHandler = handler; 80 mNetwork = nai; 81 } 82 83 /** 84 * Determines whether a network requires clat. 85 * @param network the NetworkAgentInfo corresponding to the network. 86 * @return true if the network requires clat, false otherwise. 87 */ 88 public static boolean requiresClat(NetworkAgentInfo nai) { 89 final int netType = nai.networkInfo.getType(); 90 final boolean connected = nai.networkInfo.isConnected(); 91 final boolean hasIPv4Address = 92 (nai.linkProperties != null) ? nai.linkProperties.hasIPv4Address() : false; 93 // Only support clat on mobile for now. 94 return netType == TYPE_MOBILE && connected && !hasIPv4Address; 95 } 96 97 /** 98 * Determines whether clatd is started. Always true, except a) if start has not yet been called, 99 * or b) if our interface was removed. 100 */ 101 public boolean isStarted() { 102 return mIface != null; 103 } 104 105 /** 106 * Clears internal state. Must not be called by ConnectivityService. 107 */ 108 private void clear() { 109 mIface = null; 110 mBaseIface = null; 111 mIsRunning = false; 112 } 113 114 /** 115 * Starts the clat daemon. Called by ConnectivityService on the handler thread. 116 */ 117 public void start() { 118 if (isStarted()) { 119 Slog.e(TAG, "startClat: already started"); 120 return; 121 } 122 123 if (mNetwork.linkProperties == null) { 124 Slog.e(TAG, "startClat: Can't start clat with null LinkProperties"); 125 return; 126 } 127 128 try { 129 mNMService.registerObserver(this); 130 } catch(RemoteException e) { 131 Slog.e(TAG, "startClat: Can't register interface observer for clat on " + mNetwork); 132 return; 133 } 134 135 mBaseIface = mNetwork.linkProperties.getInterfaceName(); 136 if (mBaseIface == null) { 137 Slog.e(TAG, "startClat: Can't start clat on null interface"); 138 return; 139 } 140 mIface = CLAT_PREFIX + mBaseIface; 141 // From now on, isStarted() will return true. 142 143 Slog.i(TAG, "Starting clatd on " + mBaseIface); 144 try { 145 mNMService.startClatd(mBaseIface); 146 } catch(RemoteException|IllegalStateException e) { 147 Slog.e(TAG, "Error starting clatd: " + e); 148 } 149 } 150 151 /** 152 * Stops the clat daemon. Called by ConnectivityService on the handler thread. 153 */ 154 public void stop() { 155 if (isStarted()) { 156 Slog.i(TAG, "Stopping clatd"); 157 try { 158 mNMService.stopClatd(mBaseIface); 159 } catch(RemoteException|IllegalStateException e) { 160 Slog.e(TAG, "Error stopping clatd: " + e); 161 } 162 // When clatd stops and its interface is deleted, interfaceRemoved() will notify 163 // ConnectivityService and call clear(). 164 } else { 165 Slog.e(TAG, "clatd: already stopped"); 166 } 167 } 168 169 private void updateConnectivityService(LinkProperties lp) { 170 Message msg = mHandler.obtainMessage(NetworkAgent.EVENT_NETWORK_PROPERTIES_CHANGED, lp); 171 msg.replyTo = mNetwork.messenger; 172 Slog.i(TAG, "sending message to ConnectivityService: " + msg); 173 msg.sendToTarget(); 174 } 175 176 /** 177 * Copies the stacked clat link in oldLp, if any, to the LinkProperties in mNetwork. 178 * This is necessary because the LinkProperties in mNetwork come from the transport layer, which 179 * has no idea that 464xlat is running on top of it. 180 */ 181 public void fixupLinkProperties(LinkProperties oldLp) { 182 if (mNetwork.clatd != null && 183 mIsRunning && 184 mNetwork.linkProperties != null && 185 !mNetwork.linkProperties.getAllInterfaceNames().contains(mIface)) { 186 Slog.d(TAG, "clatd running, updating NAI for " + mIface); 187 for (LinkProperties stacked: oldLp.getStackedLinks()) { 188 if (mIface.equals(stacked.getInterfaceName())) { 189 mNetwork.linkProperties.addStackedLink(stacked); 190 break; 191 } 192 } 193 } 194 } 195 196 private LinkProperties makeLinkProperties(LinkAddress clatAddress) { 197 LinkProperties stacked = new LinkProperties(); 198 stacked.setInterfaceName(mIface); 199 200 // Although the clat interface is a point-to-point tunnel, we don't 201 // point the route directly at the interface because some apps don't 202 // understand routes without gateways (see, e.g., http://b/9597256 203 // http://b/9597516). Instead, set the next hop of the route to the 204 // clat IPv4 address itself (for those apps, it doesn't matter what 205 // the IP of the gateway is, only that there is one). 206 RouteInfo ipv4Default = new RouteInfo( 207 new LinkAddress(Inet4Address.ANY, 0), 208 clatAddress.getAddress(), mIface); 209 stacked.addRoute(ipv4Default); 210 stacked.addLinkAddress(clatAddress); 211 return stacked; 212 } 213 214 @Override 215 public void interfaceAdded(String iface) { 216 // Called by the InterfaceObserver on its own thread, so can race with stop(). 217 if (isStarted() && mIface.equals(iface)) { 218 Slog.i(TAG, "interface " + iface + " added, mIsRunning " + mIsRunning + "->true"); 219 220 LinkAddress clatAddress; 221 try { 222 InterfaceConfiguration config = mNMService.getInterfaceConfig(iface); 223 clatAddress = config.getLinkAddress(); 224 } catch(RemoteException e) { 225 Slog.e(TAG, "Error getting link properties: " + e); 226 return; 227 } 228 229 if (!mIsRunning) { 230 mIsRunning = true; 231 LinkProperties lp = new LinkProperties(mNetwork.linkProperties); 232 lp.addStackedLink(makeLinkProperties(clatAddress)); 233 Slog.i(TAG, "Adding stacked link " + mIface + " on top of " + mBaseIface); 234 updateConnectivityService(lp); 235 } 236 } 237 } 238 239 @Override 240 public void interfaceRemoved(String iface) { 241 if (isStarted() && mIface.equals(iface)) { 242 Slog.i(TAG, "interface " + iface + " removed, mIsRunning " + mIsRunning + "->false"); 243 244 if (mIsRunning) { 245 // The interface going away likely means clatd has crashed. Ask netd to stop it, 246 // because otherwise when we try to start it again on the same base interface netd 247 // will complain that it's already started. 248 // 249 // Note that this method can be called by the interface observer at the same time 250 // that ConnectivityService calls stop(). In this case, the second call to 251 // stopClatd() will just throw IllegalStateException, which we'll ignore. 252 try { 253 mNMService.unregisterObserver(this); 254 mNMService.stopClatd(mBaseIface); 255 } catch (RemoteException|IllegalStateException e) { 256 // Well, we tried. 257 } 258 LinkProperties lp = new LinkProperties(mNetwork.linkProperties); 259 lp.removeStackedLink(mIface); 260 clear(); 261 updateConnectivityService(lp); 262 } 263 } 264 } 265} 266