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 android.net.InterfaceConfiguration; 20 import android.net.ConnectivityManager; 21 import android.net.LinkAddress; 22 import android.net.LinkProperties; 23 import android.net.RouteInfo; 24 import android.os.INetworkManagementService; 25 import android.os.RemoteException; 26 import android.util.Slog; 27 28 import com.android.internal.util.ArrayUtils; 29 import com.android.server.net.BaseNetworkObserver; 30 31 import java.net.Inet4Address; 32 import java.util.Objects; 33 34 /** 35 * Class to manage a 464xlat CLAT daemon. Nat464Xlat is not thread safe and should be manipulated 36 * from a consistent and unique thread context. It is the responsibility of ConnectivityService to 37 * call into this class from its own Handler thread. 38 * 39 * @hide 40 */ 41 public class Nat464Xlat extends BaseNetworkObserver { 42 private static final String TAG = Nat464Xlat.class.getSimpleName(); 43 44 // This must match the interface prefix in clatd.c. 45 private static final String CLAT_PREFIX = "v4-"; 46 47 // The network types we will start clatd on, 48 // allowing clat only on networks for which we can support IPv6-only. 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 // The network we're running on, and its type. 58 private final NetworkAgentInfo mNetwork; 59 60 private enum State { 61 IDLE, // start() not called. Base iface and stacked iface names are null. 62 STARTING, // start() called. Base iface and stacked iface names are known. 63 RUNNING, // start() called, and the stacked iface is known to be up. 64 STOPPING; // stop() called, this Nat464Xlat is still registered as a network observer for 65 // the stacked interface. 66 } 67 68 private String mBaseIface; 69 private String mIface; 70 private State mState = State.IDLE; 71 72 public Nat464Xlat(INetworkManagementService nmService, NetworkAgentInfo nai) { 73 mNMService = nmService; 74 mNetwork = nai; 75 } 76 77 /** 78 * Determines whether a network requires clat. 79 * @param network the NetworkAgentInfo corresponding to the network. 80 * @return true if the network requires clat, false otherwise. 81 */ 82 public static boolean requiresClat(NetworkAgentInfo nai) { 83 // TODO: migrate to NetworkCapabilities.TRANSPORT_*. 84 final int netType = nai.networkInfo.getType(); 85 final boolean supported = ArrayUtils.contains(NETWORK_TYPES, nai.networkInfo.getType()); 86 // TODO: this should also consider if the network is in SUSPENDED state to avoid stopping 87 // clatd in SUSPENDED state. 88 final boolean connected = nai.networkInfo.isConnected(); 89 // We only run clat on networks that don't have a native IPv4 address. 90 final boolean hasIPv4Address = 91 (nai.linkProperties != null) && nai.linkProperties.hasIPv4Address(); 92 return supported && connected && !hasIPv4Address; 93 } 94 95 /** 96 * @return true if clatd has been started and has not yet stopped. 97 * A true result corresponds to internal states STARTING and RUNNING. 98 */ 99 public boolean isStarted() { 100 return mState != State.IDLE; 101 } 102 103 /** 104 * @return true if clatd has been started but the stacked interface is not yet up. 105 */ 106 public boolean isStarting() { 107 return mState == State.STARTING; 108 } 109 110 /** 111 * @return true if clatd has been started and the stacked interface is up. 112 */ 113 public boolean isRunning() { 114 return mState == State.RUNNING; 115 } 116 117 /** 118 * @return true if clatd has been stopped. 119 */ 120 public boolean isStopping() { 121 return mState == State.STOPPING; 122 } 123 124 /** 125 * Start clatd, register this Nat464Xlat as a network observer for the stacked interface, 126 * and set internal state. 127 */ 128 private void enterStartingState(String baseIface) { 129 try { 130 mNMService.registerObserver(this); 131 } catch(RemoteException e) { 132 Slog.e(TAG, 133 "startClat: Can't register interface observer for clat on " + mNetwork.name()); 134 return; 135 } 136 try { 137 mNMService.startClatd(baseIface); 138 } catch(RemoteException|IllegalStateException e) { 139 Slog.e(TAG, "Error starting clatd on " + baseIface, e); 140 } 141 mIface = CLAT_PREFIX + baseIface; 142 mBaseIface = baseIface; 143 mState = State.STARTING; 144 } 145 146 /** 147 * Enter running state just after getting confirmation that the stacked interface is up, and 148 * turn ND offload off if on WiFi. 149 */ 150 private void enterRunningState() { 151 maybeSetIpv6NdOffload(mBaseIface, false); 152 mState = State.RUNNING; 153 } 154 155 /** 156 * Stop clatd, and turn ND offload on if it had been turned off. 157 */ 158 private void enterStoppingState() { 159 if (isRunning()) { 160 maybeSetIpv6NdOffload(mBaseIface, true); 161 } 162 163 try { 164 mNMService.stopClatd(mBaseIface); 165 } catch(RemoteException|IllegalStateException e) { 166 Slog.e(TAG, "Error stopping clatd on " + mBaseIface, e); 167 } 168 169 mState = State.STOPPING; 170 } 171 172 /** 173 * Unregister as a base observer for the stacked interface, and clear internal state. 174 */ 175 private void enterIdleState() { 176 try { 177 mNMService.unregisterObserver(this); 178 } catch(RemoteException|IllegalStateException e) { 179 Slog.e(TAG, "Error unregistering clatd observer on " + mBaseIface, e); 180 } 181 182 mIface = null; 183 mBaseIface = null; 184 mState = State.IDLE; 185 } 186 187 /** 188 * Starts the clat daemon. 189 */ 190 public void start() { 191 if (isStarted()) { 192 Slog.e(TAG, "startClat: already started"); 193 return; 194 } 195 196 if (mNetwork.linkProperties == null) { 197 Slog.e(TAG, "startClat: Can't start clat with null LinkProperties"); 198 return; 199 } 200 201 String baseIface = mNetwork.linkProperties.getInterfaceName(); 202 if (baseIface == null) { 203 Slog.e(TAG, "startClat: Can't start clat on null interface"); 204 return; 205 } 206 // TODO: should we only do this if mNMService.startClatd() succeeds? 207 Slog.i(TAG, "Starting clatd on " + baseIface); 208 enterStartingState(baseIface); 209 } 210 211 /** 212 * Stops the clat daemon. 213 */ 214 public void stop() { 215 if (!isStarted()) { 216 return; 217 } 218 Slog.i(TAG, "Stopping clatd on " + mBaseIface); 219 220 boolean wasStarting = isStarting(); 221 enterStoppingState(); 222 if (wasStarting) { 223 enterIdleState(); 224 } 225 } 226 227 /** 228 * Copies the stacked clat link in oldLp, if any, to the LinkProperties in mNetwork. 229 * This is necessary because the LinkProperties in mNetwork come from the transport layer, which 230 * has no idea that 464xlat is running on top of it. 231 */ 232 public void fixupLinkProperties(LinkProperties oldLp) { 233 if (!isRunning()) { 234 return; 235 } 236 LinkProperties lp = mNetwork.linkProperties; 237 if (lp == null || lp.getAllInterfaceNames().contains(mIface)) { 238 return; 239 } 240 241 Slog.d(TAG, "clatd running, updating NAI for " + mIface); 242 for (LinkProperties stacked: oldLp.getStackedLinks()) { 243 if (Objects.equals(mIface, stacked.getInterfaceName())) { 244 lp.addStackedLink(stacked); 245 return; 246 } 247 } 248 } 249 250 private LinkProperties makeLinkProperties(LinkAddress clatAddress) { 251 LinkProperties stacked = new LinkProperties(); 252 stacked.setInterfaceName(mIface); 253 254 // Although the clat interface is a point-to-point tunnel, we don't 255 // point the route directly at the interface because some apps don't 256 // understand routes without gateways (see, e.g., http://b/9597256 257 // http://b/9597516). Instead, set the next hop of the route to the 258 // clat IPv4 address itself (for those apps, it doesn't matter what 259 // the IP of the gateway is, only that there is one). 260 RouteInfo ipv4Default = new RouteInfo( 261 new LinkAddress(Inet4Address.ANY, 0), 262 clatAddress.getAddress(), mIface); 263 stacked.addRoute(ipv4Default); 264 stacked.addLinkAddress(clatAddress); 265 return stacked; 266 } 267 268 private LinkAddress getLinkAddress(String iface) { 269 try { 270 InterfaceConfiguration config = mNMService.getInterfaceConfig(iface); 271 return config.getLinkAddress(); 272 } catch(RemoteException|IllegalStateException e) { 273 Slog.e(TAG, "Error getting link properties: " + e); 274 return null; 275 } 276 } 277 278 private void maybeSetIpv6NdOffload(String iface, boolean on) { 279 // TODO: migrate to NetworkCapabilities.TRANSPORT_*. 280 if (mNetwork.networkInfo.getType() != ConnectivityManager.TYPE_WIFI) { 281 return; 282 } 283 try { 284 Slog.d(TAG, (on ? "En" : "Dis") + "abling ND offload on " + iface); 285 mNMService.setInterfaceIpv6NdOffload(iface, on); 286 } catch(RemoteException|IllegalStateException e) { 287 Slog.w(TAG, "Changing IPv6 ND offload on " + iface + "failed: " + e); 288 } 289 } 290 291 /** 292 * Adds stacked link on base link and transitions to RUNNING state. 293 */ 294 private void handleInterfaceLinkStateChanged(String iface, boolean up) { 295 if (!isStarting() || !up || !Objects.equals(mIface, iface)) { 296 return; 297 } 298 299 LinkAddress clatAddress = getLinkAddress(iface); 300 if (clatAddress == null) { 301 Slog.e(TAG, "clatAddress was null for stacked iface " + iface); 302 return; 303 } 304 305 Slog.i(TAG, String.format("interface %s is up, adding stacked link %s on top of %s", 306 mIface, mIface, mBaseIface)); 307 enterRunningState(); 308 LinkProperties lp = new LinkProperties(mNetwork.linkProperties); 309 lp.addStackedLink(makeLinkProperties(clatAddress)); 310 mNetwork.connService().handleUpdateLinkProperties(mNetwork, lp); 311 } 312 313 /** 314 * Removes stacked link on base link and transitions to IDLE state. 315 */ 316 private void handleInterfaceRemoved(String iface) { 317 if (!Objects.equals(mIface, iface)) { 318 return; 319 } 320 if (!isRunning() && !isStopping()) { 321 return; 322 } 323 324 Slog.i(TAG, "interface " + iface + " removed"); 325 if (!isStopping()) { 326 // Ensure clatd is stopped if stop() has not been called: this likely means that clatd 327 // has crashed. 328 enterStoppingState(); 329 } 330 enterIdleState(); 331 LinkProperties lp = new LinkProperties(mNetwork.linkProperties); 332 lp.removeStackedLink(iface); 333 mNetwork.connService().handleUpdateLinkProperties(mNetwork, lp); 334 } 335 336 @Override 337 public void interfaceLinkStateChanged(String iface, boolean up) { 338 mNetwork.handler().post(() -> { handleInterfaceLinkStateChanged(iface, up); }); 339 } 340 341 @Override 342 public void interfaceRemoved(String iface) { 343 mNetwork.handler().post(() -> { handleInterfaceRemoved(iface); }); 344 } 345 346 @Override 347 public String toString() { 348 return "mBaseIface: " + mBaseIface + ", mIface: " + mIface + ", mState: " + mState; 349 } 350 } 351