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 17 package com.android.server.connectivity; 18 19 import java.net.Inet4Address; 20 21 import android.content.Context; 22 import android.net.InterfaceConfiguration; 23 import android.net.ConnectivityManager; 24 import android.net.LinkAddress; 25 import android.net.LinkProperties; 26 import android.net.NetworkAgent; 27 import android.net.RouteInfo; 28 import android.os.Handler; 29 import android.os.Message; 30 import android.os.INetworkManagementService; 31 import android.os.RemoteException; 32 import android.util.Slog; 33 34 import com.android.server.net.BaseNetworkObserver; 35 import com.android.internal.util.ArrayUtils; 36 37 /** 38 * @hide 39 * 40 * Class to manage a 464xlat CLAT daemon. 41 */ 42 public class Nat464Xlat extends BaseNetworkObserver { 43 private static final String TAG = "Nat464Xlat"; 44 45 // This must match the interface prefix in clatd.c. 46 private static final String CLAT_PREFIX = "v4-"; 47 48 // The network types we will start clatd on. 49 private static final int[] NETWORK_TYPES = { 50 ConnectivityManager.TYPE_MOBILE, 51 ConnectivityManager.TYPE_WIFI, 52 ConnectivityManager.TYPE_ETHERNET, 53 }; 54 55 private final INetworkManagementService mNMService; 56 57 // ConnectivityService Handler for LinkProperties updates. 58 private final Handler mHandler; 59 60 // The network we're running on, and its type. 61 private final NetworkAgentInfo mNetwork; 62 63 // Internal state variables. 64 // 65 // The possible states are: 66 // - Idle: start() not called. Everything is null. 67 // - Starting: start() called. Interfaces are non-null. isStarted() returns true. 68 // mIsRunning is false. 69 // - Running: start() called, and interfaceLinkStateChanged() told us that mIface is up. 70 // mIsRunning is true. 71 // 72 // Once mIface is non-null and isStarted() is true, methods called by ConnectivityService on 73 // its handler thread must not modify any internal state variables; they are only updated by the 74 // interface observers, called on the notification threads. 75 private String mBaseIface; 76 private String mIface; 77 private boolean mIsRunning; 78 79 public Nat464Xlat( 80 Context context, INetworkManagementService nmService, 81 Handler handler, NetworkAgentInfo nai) { 82 mNMService = nmService; 83 mHandler = handler; 84 mNetwork = nai; 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 // Only support clat on mobile and wifi for now, because these are the only IPv6-only 98 // networks we can connect to. 99 return connected && !hasIPv4Address && ArrayUtils.contains(NETWORK_TYPES, netType); 100 } 101 102 /** 103 * Determines whether clatd is started. Always true, except a) if start has not yet been called, 104 * or b) if our interface was removed. 105 */ 106 public boolean isStarted() { 107 return mIface != null; 108 } 109 110 /** 111 * Clears internal state. Must not be called by ConnectivityService. 112 */ 113 private void clear() { 114 mIface = null; 115 mBaseIface = null; 116 mIsRunning = false; 117 } 118 119 /** 120 * Starts the clat daemon. Called by ConnectivityService on the handler thread. 121 */ 122 public void start() { 123 if (isStarted()) { 124 Slog.e(TAG, "startClat: already started"); 125 return; 126 } 127 128 if (mNetwork.linkProperties == null) { 129 Slog.e(TAG, "startClat: Can't start clat with null LinkProperties"); 130 return; 131 } 132 133 try { 134 mNMService.registerObserver(this); 135 } catch(RemoteException e) { 136 Slog.e(TAG, "startClat: Can't register interface observer for clat on " + mNetwork); 137 return; 138 } 139 140 mBaseIface = mNetwork.linkProperties.getInterfaceName(); 141 if (mBaseIface == null) { 142 Slog.e(TAG, "startClat: Can't start clat on null interface"); 143 return; 144 } 145 mIface = CLAT_PREFIX + mBaseIface; 146 // From now on, isStarted() will return true. 147 148 Slog.i(TAG, "Starting clatd on " + mBaseIface); 149 try { 150 mNMService.startClatd(mBaseIface); 151 } catch(RemoteException|IllegalStateException e) { 152 Slog.e(TAG, "Error starting clatd: " + e); 153 } 154 } 155 156 /** 157 * Stops the clat daemon. Called by ConnectivityService on the handler thread. 158 */ 159 public void stop() { 160 if (isStarted()) { 161 Slog.i(TAG, "Stopping clatd"); 162 try { 163 mNMService.stopClatd(mBaseIface); 164 } catch(RemoteException|IllegalStateException e) { 165 Slog.e(TAG, "Error stopping clatd: " + e); 166 } 167 // When clatd stops and its interface is deleted, interfaceRemoved() will notify 168 // ConnectivityService and call clear(). 169 } else { 170 Slog.e(TAG, "clatd: already stopped"); 171 } 172 } 173 174 private void updateConnectivityService(LinkProperties lp) { 175 Message msg = mHandler.obtainMessage(NetworkAgent.EVENT_NETWORK_PROPERTIES_CHANGED, lp); 176 msg.replyTo = mNetwork.messenger; 177 Slog.i(TAG, "sending message to ConnectivityService: " + msg); 178 msg.sendToTarget(); 179 } 180 181 /** 182 * Copies the stacked clat link in oldLp, if any, to the LinkProperties in mNetwork. 183 * This is necessary because the LinkProperties in mNetwork come from the transport layer, which 184 * has no idea that 464xlat is running on top of it. 185 */ 186 public void fixupLinkProperties(LinkProperties oldLp) { 187 if (mNetwork.clatd != null && 188 mIsRunning && 189 mNetwork.linkProperties != null && 190 !mNetwork.linkProperties.getAllInterfaceNames().contains(mIface)) { 191 Slog.d(TAG, "clatd running, updating NAI for " + mIface); 192 for (LinkProperties stacked: oldLp.getStackedLinks()) { 193 if (mIface.equals(stacked.getInterfaceName())) { 194 mNetwork.linkProperties.addStackedLink(stacked); 195 break; 196 } 197 } 198 } 199 } 200 201 private LinkProperties makeLinkProperties(LinkAddress clatAddress) { 202 LinkProperties stacked = new LinkProperties(); 203 stacked.setInterfaceName(mIface); 204 205 // Although the clat interface is a point-to-point tunnel, we don't 206 // point the route directly at the interface because some apps don't 207 // understand routes without gateways (see, e.g., http://b/9597256 208 // http://b/9597516). Instead, set the next hop of the route to the 209 // clat IPv4 address itself (for those apps, it doesn't matter what 210 // the IP of the gateway is, only that there is one). 211 RouteInfo ipv4Default = new RouteInfo( 212 new LinkAddress(Inet4Address.ANY, 0), 213 clatAddress.getAddress(), mIface); 214 stacked.addRoute(ipv4Default); 215 stacked.addLinkAddress(clatAddress); 216 return stacked; 217 } 218 219 private LinkAddress getLinkAddress(String iface) { 220 try { 221 InterfaceConfiguration config = mNMService.getInterfaceConfig(iface); 222 return config.getLinkAddress(); 223 } catch(RemoteException|IllegalStateException e) { 224 Slog.e(TAG, "Error getting link properties: " + e); 225 return null; 226 } 227 } 228 229 private void maybeSetIpv6NdOffload(String iface, boolean on) { 230 if (mNetwork.networkInfo.getType() != ConnectivityManager.TYPE_WIFI) { 231 return; 232 } 233 try { 234 Slog.d(TAG, (on ? "En" : "Dis") + "abling ND offload on " + iface); 235 mNMService.setInterfaceIpv6NdOffload(iface, on); 236 } catch(RemoteException|IllegalStateException e) { 237 Slog.w(TAG, "Changing IPv6 ND offload on " + iface + "failed: " + e); 238 } 239 } 240 241 @Override 242 public void interfaceLinkStateChanged(String iface, boolean up) { 243 // Called by the InterfaceObserver on its own thread, so can race with stop(). 244 if (isStarted() && up && mIface.equals(iface)) { 245 Slog.i(TAG, "interface " + iface + " is up, mIsRunning " + mIsRunning + "->true"); 246 247 if (!mIsRunning) { 248 LinkAddress clatAddress = getLinkAddress(iface); 249 if (clatAddress == null) { 250 return; 251 } 252 mIsRunning = true; 253 maybeSetIpv6NdOffload(mBaseIface, false); 254 LinkProperties lp = new LinkProperties(mNetwork.linkProperties); 255 lp.addStackedLink(makeLinkProperties(clatAddress)); 256 Slog.i(TAG, "Adding stacked link " + mIface + " on top of " + mBaseIface); 257 updateConnectivityService(lp); 258 } 259 } 260 } 261 262 @Override 263 public void interfaceRemoved(String iface) { 264 if (isStarted() && mIface.equals(iface)) { 265 Slog.i(TAG, "interface " + iface + " removed, mIsRunning " + mIsRunning + "->false"); 266 267 if (mIsRunning) { 268 // The interface going away likely means clatd has crashed. Ask netd to stop it, 269 // because otherwise when we try to start it again on the same base interface netd 270 // will complain that it's already started. 271 // 272 // Note that this method can be called by the interface observer at the same time 273 // that ConnectivityService calls stop(). In this case, the second call to 274 // stopClatd() will just throw IllegalStateException, which we'll ignore. 275 try { 276 mNMService.unregisterObserver(this); 277 mNMService.stopClatd(mBaseIface); 278 } catch (RemoteException|IllegalStateException e) { 279 // Well, we tried. 280 } 281 maybeSetIpv6NdOffload(mBaseIface, true); 282 LinkProperties lp = new LinkProperties(mNetwork.linkProperties); 283 lp.removeStackedLink(mIface); 284 clear(); 285 updateConnectivityService(lp); 286 } 287 } 288 } 289 } 290
