Nat464Xlat.java revision e21a26b3ba78b0238f4ed4a09b43319a2320fbaa
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; 20import static android.net.ConnectivityManager.TYPE_WIFI; 21 22import java.net.Inet4Address; 23 24import android.content.Context; 25import android.net.IConnectivityManager; 26import android.net.InterfaceConfiguration; 27import android.net.LinkAddress; 28import android.net.LinkProperties; 29import android.net.NetworkAgent; 30import android.net.NetworkUtils; 31import android.net.RouteInfo; 32import android.os.Handler; 33import android.os.Message; 34import android.os.Messenger; 35import android.os.INetworkManagementService; 36import android.os.RemoteException; 37import android.util.Slog; 38 39import com.android.server.net.BaseNetworkObserver; 40 41/** 42 * @hide 43 * 44 * Class to manage a 464xlat CLAT daemon. 45 */ 46public class Nat464Xlat extends BaseNetworkObserver { 47 private static final String TAG = "Nat464Xlat"; 48 49 // This must match the interface prefix in clatd.c. 50 private static final String CLAT_PREFIX = "v4-"; 51 52 private final INetworkManagementService mNMService; 53 54 // ConnectivityService Handler for LinkProperties updates. 55 private final Handler mHandler; 56 57 // The network we're running on, and its type. 58 private final NetworkAgentInfo mNetwork; 59 60 // Internal state variables. 61 // 62 // The possible states are: 63 // - Idle: start() not called. Everything is null. 64 // - Starting: start() called. Interfaces are non-null. isStarted() returns true. 65 // mIsRunning is false. 66 // - Running: start() called, and interfaceAdded() told us that mIface is up. Clat IP address 67 // is non-null. mIsRunning is true. 68 // 69 // Once mIface is non-null and isStarted() is true, methods called by ConnectivityService on 70 // its handler thread must not modify any internal state variables; they are only updated by the 71 // interface observers, called on the notification threads. 72 private String mBaseIface; 73 private String mIface; 74 private boolean mIsRunning; 75 76 public Nat464Xlat( 77 Context context, INetworkManagementService nmService, 78 Handler handler, NetworkAgentInfo nai) { 79 mNMService = nmService; 80 mHandler = handler; 81 mNetwork = nai; 82 } 83 84 /** 85 * Determines whether a network requires clat. 86 * @param network the NetworkAgentInfo corresponding to the network. 87 * @return true if the network requires clat, false otherwise. 88 */ 89 public static boolean requiresClat(NetworkAgentInfo nai) { 90 final int netType = nai.networkInfo.getType(); 91 final boolean connected = nai.networkInfo.isConnected(); 92 final boolean hasIPv4Address = 93 (nai.linkProperties != null) ? nai.linkProperties.hasIPv4Address() : false; 94 // Only support clat on mobile for now. 95 return netType == TYPE_MOBILE && connected && !hasIPv4Address; 96 } 97 98 /** 99 * Determines whether clatd is started. Always true, except a) if start has not yet been called, 100 * or b) if our interface was removed. 101 */ 102 public boolean isStarted() { 103 return mIface != null; 104 } 105 106 /** 107 * Clears internal state. Must not be called by ConnectivityService. 108 */ 109 private void clear() { 110 mIface = null; 111 mBaseIface = null; 112 mIsRunning = false; 113 } 114 115 /** 116 * Starts the clat daemon. Called by ConnectivityService on the handler thread. 117 */ 118 public void start() { 119 if (isStarted()) { 120 Slog.e(TAG, "startClat: already started"); 121 return; 122 } 123 124 if (mNetwork.linkProperties == null) { 125 Slog.e(TAG, "startClat: Can't start clat with null LinkProperties"); 126 return; 127 } 128 129 try { 130 mNMService.registerObserver(this); 131 } catch(RemoteException e) { 132 Slog.e(TAG, "startClat: Can't register interface observer for clat on " + mNetwork); 133 return; 134 } 135 136 mBaseIface = mNetwork.linkProperties.getInterfaceName(); 137 if (mBaseIface == null) { 138 Slog.e(TAG, "startClat: Can't start clat on null interface"); 139 return; 140 } 141 mIface = CLAT_PREFIX + mBaseIface; 142 // From now on, isStarted() will return true. 143 144 Slog.i(TAG, "Starting clatd on " + mBaseIface); 145 try { 146 mNMService.startClatd(mBaseIface); 147 } catch(RemoteException|IllegalStateException e) { 148 Slog.e(TAG, "Error starting clatd: " + e); 149 } 150 } 151 152 /** 153 * Stops the clat daemon. Called by ConnectivityService on the handler thread. 154 */ 155 public void stop() { 156 if (isStarted()) { 157 Slog.i(TAG, "Stopping clatd"); 158 try { 159 mNMService.stopClatd(mBaseIface); 160 } catch(RemoteException|IllegalStateException e) { 161 Slog.e(TAG, "Error stopping clatd: " + e); 162 } 163 // When clatd stops and its interface is deleted, interfaceRemoved() will notify 164 // ConnectivityService and call clear(). 165 } else { 166 Slog.e(TAG, "clatd: already stopped"); 167 } 168 } 169 170 private void updateConnectivityService(LinkProperties lp) { 171 Message msg = mHandler.obtainMessage(NetworkAgent.EVENT_NETWORK_PROPERTIES_CHANGED, lp); 172 msg.replyTo = mNetwork.messenger; 173 Slog.i(TAG, "sending message to ConnectivityService: " + msg); 174 msg.sendToTarget(); 175 } 176 177 /** 178 * Copies the stacked clat link in oldLp, if any, to the LinkProperties in mNetwork. 179 * This is necessary because the LinkProperties in mNetwork come from the transport layer, which 180 * has no idea that 464xlat is running on top of it. 181 */ 182 public void fixupLinkProperties(LinkProperties oldLp) { 183 if (mNetwork.clatd != null && 184 mIsRunning && 185 mNetwork.linkProperties != null && 186 !mNetwork.linkProperties.getAllInterfaceNames().contains(mIface)) { 187 Slog.d(TAG, "clatd running, updating NAI for " + mIface); 188 for (LinkProperties stacked: oldLp.getStackedLinks()) { 189 if (mIface.equals(stacked.getInterfaceName())) { 190 mNetwork.linkProperties.addStackedLink(stacked); 191 break; 192 } 193 } 194 } 195 } 196 197 private LinkProperties makeLinkProperties(LinkAddress clatAddress) { 198 LinkProperties stacked = new LinkProperties(); 199 stacked.setInterfaceName(mIface); 200 201 // Although the clat interface is a point-to-point tunnel, we don't 202 // point the route directly at the interface because some apps don't 203 // understand routes without gateways (see, e.g., http://b/9597256 204 // http://b/9597516). Instead, set the next hop of the route to the 205 // clat IPv4 address itself (for those apps, it doesn't matter what 206 // the IP of the gateway is, only that there is one). 207 RouteInfo ipv4Default = new RouteInfo( 208 new LinkAddress(Inet4Address.ANY, 0), 209 clatAddress.getAddress(), mIface); 210 stacked.addRoute(ipv4Default); 211 stacked.addLinkAddress(clatAddress); 212 return stacked; 213 } 214 215 private LinkAddress getLinkAddress(String iface) { 216 try { 217 InterfaceConfiguration config = mNMService.getInterfaceConfig(iface); 218 return config.getLinkAddress(); 219 } catch(RemoteException|IllegalStateException e) { 220 Slog.e(TAG, "Error getting link properties: " + e); 221 return null; 222 } 223 } 224 225 private void maybeSetIpv6NdOffload(String iface, boolean on) { 226 if (mNetwork.networkInfo.getType() != TYPE_WIFI) { 227 return; 228 } 229 try { 230 Slog.d(TAG, (on ? "En" : "Dis") + "abling ND offload on " + iface); 231 mNMService.setInterfaceIpv6NdOffload(iface, on); 232 } catch(RemoteException|IllegalStateException e) { 233 Slog.w(TAG, "Changing IPv6 ND offload on " + iface + "failed: " + e); 234 } 235 } 236 237 @Override 238 public void interfaceAdded(String iface) { 239 // Called by the InterfaceObserver on its own thread, so can race with stop(). 240 if (isStarted() && mIface.equals(iface)) { 241 Slog.i(TAG, "interface " + iface + " added, mIsRunning " + mIsRunning + "->true"); 242 243 if (!mIsRunning) { 244 LinkAddress clatAddress = getLinkAddress(iface); 245 if (clatAddress == null) { 246 return; 247 } 248 mIsRunning = true; 249 maybeSetIpv6NdOffload(mBaseIface, false); 250 LinkProperties lp = new LinkProperties(mNetwork.linkProperties); 251 lp.addStackedLink(makeLinkProperties(clatAddress)); 252 Slog.i(TAG, "Adding stacked link " + mIface + " on top of " + mBaseIface); 253 updateConnectivityService(lp); 254 } 255 } 256 } 257 258 @Override 259 public void interfaceRemoved(String iface) { 260 if (isStarted() && mIface.equals(iface)) { 261 Slog.i(TAG, "interface " + iface + " removed, mIsRunning " + mIsRunning + "->false"); 262 263 if (mIsRunning) { 264 // The interface going away likely means clatd has crashed. Ask netd to stop it, 265 // because otherwise when we try to start it again on the same base interface netd 266 // will complain that it's already started. 267 // 268 // Note that this method can be called by the interface observer at the same time 269 // that ConnectivityService calls stop(). In this case, the second call to 270 // stopClatd() will just throw IllegalStateException, which we'll ignore. 271 try { 272 mNMService.unregisterObserver(this); 273 mNMService.stopClatd(mBaseIface); 274 } catch (RemoteException|IllegalStateException e) { 275 // Well, we tried. 276 } 277 maybeSetIpv6NdOffload(mBaseIface, true); 278 LinkProperties lp = new LinkProperties(mNetwork.linkProperties); 279 lp.removeStackedLink(mIface); 280 clear(); 281 updateConnectivityService(lp); 282 } 283 } 284 } 285} 286