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 static android.net.ConnectivityManager.TYPE_MOBILE; 20 import static android.net.ConnectivityManager.TYPE_WIFI; 21 22 import java.net.Inet4Address; 23 24 import android.content.Context; 25 import android.net.IConnectivityManager; 26 import android.net.InterfaceConfiguration; 27 import android.net.LinkAddress; 28 import android.net.LinkProperties; 29 import android.net.NetworkAgent; 30 import android.net.NetworkUtils; 31 import android.net.RouteInfo; 32 import android.os.Handler; 33 import android.os.Message; 34 import android.os.Messenger; 35 import android.os.INetworkManagementService; 36 import android.os.RemoteException; 37 import android.util.Slog; 38 39 import com.android.server.net.BaseNetworkObserver; 40 41 /** 42 * @hide 43 * 44 * Class to manage a 464xlat CLAT daemon. 45 */ 46 public 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 interfaceLinkStateChanged() told us that mIface is up. 67 // 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 and wifi for now, because these are the only IPv6-only 95 // networks we can connect to. 96 return connected && !hasIPv4Address && (netType == TYPE_MOBILE || netType == TYPE_WIFI); 97 } 98 99 /** 100 * Determines whether clatd is started. Always true, except a) if start has not yet been called, 101 * or b) if our interface was removed. 102 */ 103 public boolean isStarted() { 104 return mIface != null; 105 } 106 107 /** 108 * Clears internal state. Must not be called by ConnectivityService. 109 */ 110 private void clear() { 111 mIface = null; 112 mBaseIface = null; 113 mIsRunning = false; 114 } 115 116 /** 117 * Starts the clat daemon. Called by ConnectivityService on the handler thread. 118 */ 119 public void start() { 120 if (isStarted()) { 121 Slog.e(TAG, "startClat: already started"); 122 return; 123 } 124 125 if (mNetwork.linkProperties == null) { 126 Slog.e(TAG, "startClat: Can't start clat with null LinkProperties"); 127 return; 128 } 129 130 try { 131 mNMService.registerObserver(this); 132 } catch(RemoteException e) { 133 Slog.e(TAG, "startClat: Can't register interface observer for clat on " + mNetwork); 134 return; 135 } 136 137 mBaseIface = mNetwork.linkProperties.getInterfaceName(); 138 if (mBaseIface == null) { 139 Slog.e(TAG, "startClat: Can't start clat on null interface"); 140 return; 141 } 142 mIface = CLAT_PREFIX + mBaseIface; 143 // From now on, isStarted() will return true. 144 145 Slog.i(TAG, "Starting clatd on " + mBaseIface); 146 try { 147 mNMService.startClatd(mBaseIface); 148 } catch(RemoteException|IllegalStateException e) { 149 Slog.e(TAG, "Error starting clatd: " + e); 150 } 151 } 152 153 /** 154 * Stops the clat daemon. Called by ConnectivityService on the handler thread. 155 */ 156 public void stop() { 157 if (isStarted()) { 158 Slog.i(TAG, "Stopping clatd"); 159 try { 160 mNMService.stopClatd(mBaseIface); 161 } catch(RemoteException|IllegalStateException e) { 162 Slog.e(TAG, "Error stopping clatd: " + e); 163 } 164 // When clatd stops and its interface is deleted, interfaceRemoved() will notify 165 // ConnectivityService and call clear(). 166 } else { 167 Slog.e(TAG, "clatd: already stopped"); 168 } 169 } 170 171 private void updateConnectivityService(LinkProperties lp) { 172 Message msg = mHandler.obtainMessage(NetworkAgent.EVENT_NETWORK_PROPERTIES_CHANGED, lp); 173 msg.replyTo = mNetwork.messenger; 174 Slog.i(TAG, "sending message to ConnectivityService: " + msg); 175 msg.sendToTarget(); 176 } 177 178 /** 179 * Copies the stacked clat link in oldLp, if any, to the LinkProperties in mNetwork. 180 * This is necessary because the LinkProperties in mNetwork come from the transport layer, which 181 * has no idea that 464xlat is running on top of it. 182 */ 183 public void fixupLinkProperties(LinkProperties oldLp) { 184 if (mNetwork.clatd != null && 185 mIsRunning && 186 mNetwork.linkProperties != null && 187 !mNetwork.linkProperties.getAllInterfaceNames().contains(mIface)) { 188 Slog.d(TAG, "clatd running, updating NAI for " + mIface); 189 for (LinkProperties stacked: oldLp.getStackedLinks()) { 190 if (mIface.equals(stacked.getInterfaceName())) { 191 mNetwork.linkProperties.addStackedLink(stacked); 192 break; 193 } 194 } 195 } 196 } 197 198 private LinkProperties makeLinkProperties(LinkAddress clatAddress) { 199 LinkProperties stacked = new LinkProperties(); 200 stacked.setInterfaceName(mIface); 201 202 // Although the clat interface is a point-to-point tunnel, we don't 203 // point the route directly at the interface because some apps don't 204 // understand routes without gateways (see, e.g., http://b/9597256 205 // http://b/9597516). Instead, set the next hop of the route to the 206 // clat IPv4 address itself (for those apps, it doesn't matter what 207 // the IP of the gateway is, only that there is one). 208 RouteInfo ipv4Default = new RouteInfo( 209 new LinkAddress(Inet4Address.ANY, 0), 210 clatAddress.getAddress(), mIface); 211 stacked.addRoute(ipv4Default); 212 stacked.addLinkAddress(clatAddress); 213 return stacked; 214 } 215 216 private LinkAddress getLinkAddress(String iface) { 217 try { 218 InterfaceConfiguration config = mNMService.getInterfaceConfig(iface); 219 return config.getLinkAddress(); 220 } catch(RemoteException|IllegalStateException e) { 221 Slog.e(TAG, "Error getting link properties: " + e); 222 return null; 223 } 224 } 225 226 private void maybeSetIpv6NdOffload(String iface, boolean on) { 227 if (mNetwork.networkInfo.getType() != TYPE_WIFI) { 228 return; 229 } 230 try { 231 Slog.d(TAG, (on ? "En" : "Dis") + "abling ND offload on " + iface); 232 mNMService.setInterfaceIpv6NdOffload(iface, on); 233 } catch(RemoteException|IllegalStateException e) { 234 Slog.w(TAG, "Changing IPv6 ND offload on " + iface + "failed: " + e); 235 } 236 } 237 238 @Override 239 public void interfaceLinkStateChanged(String iface, boolean up) { 240 // Called by the InterfaceObserver on its own thread, so can race with stop(). 241 if (isStarted() && up && mIface.equals(iface)) { 242 Slog.i(TAG, "interface " + iface + " is up, mIsRunning " + mIsRunning + "->true"); 243 244 if (!mIsRunning) { 245 LinkAddress clatAddress = getLinkAddress(iface); 246 if (clatAddress == null) { 247 return; 248 } 249 mIsRunning = true; 250 maybeSetIpv6NdOffload(mBaseIface, false); 251 LinkProperties lp = new LinkProperties(mNetwork.linkProperties); 252 lp.addStackedLink(makeLinkProperties(clatAddress)); 253 Slog.i(TAG, "Adding stacked link " + mIface + " on top of " + mBaseIface); 254 updateConnectivityService(lp); 255 } 256 } 257 } 258 259 @Override 260 public void interfaceRemoved(String iface) { 261 if (isStarted() && mIface.equals(iface)) { 262 Slog.i(TAG, "interface " + iface + " removed, mIsRunning " + mIsRunning + "->false"); 263 264 if (mIsRunning) { 265 // The interface going away likely means clatd has crashed. Ask netd to stop it, 266 // because otherwise when we try to start it again on the same base interface netd 267 // will complain that it's already started. 268 // 269 // Note that this method can be called by the interface observer at the same time 270 // that ConnectivityService calls stop(). In this case, the second call to 271 // stopClatd() will just throw IllegalStateException, which we'll ignore. 272 try { 273 mNMService.unregisterObserver(this); 274 mNMService.stopClatd(mBaseIface); 275 } catch (RemoteException|IllegalStateException e) { 276 // Well, we tried. 277 } 278 maybeSetIpv6NdOffload(mBaseIface, true); 279 LinkProperties lp = new LinkProperties(mNetwork.linkProperties); 280 lp.removeStackedLink(mIface); 281 clear(); 282 updateConnectivityService(lp); 283 } 284 } 285 } 286 } 287