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