| /* |
| * Copyright (C) 2012 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.android.server.connectivity; |
| |
| import android.annotation.NonNull; |
| import android.net.ConnectivityManager; |
| import android.net.IDnsResolver; |
| import android.net.INetd; |
| import android.net.InetAddresses; |
| import android.net.InterfaceConfiguration; |
| import android.net.IpPrefix; |
| import android.net.LinkAddress; |
| import android.net.LinkProperties; |
| import android.net.NetworkInfo; |
| import android.net.RouteInfo; |
| import android.os.INetworkManagementService; |
| import android.os.RemoteException; |
| import android.os.ServiceSpecificException; |
| import android.util.Slog; |
| |
| import com.android.internal.annotations.VisibleForTesting; |
| import com.android.internal.util.ArrayUtils; |
| import com.android.server.net.BaseNetworkObserver; |
| |
| import java.net.Inet4Address; |
| import java.net.Inet6Address; |
| import java.util.Objects; |
| |
| /** |
| * Class to manage a 464xlat CLAT daemon. Nat464Xlat is not thread safe and should be manipulated |
| * from a consistent and unique thread context. It is the responsibility of ConnectivityService to |
| * call into this class from its own Handler thread. |
| * |
| * @hide |
| */ |
| public class Nat464Xlat extends BaseNetworkObserver { |
| private static final String TAG = Nat464Xlat.class.getSimpleName(); |
| |
| // This must match the interface prefix in clatd.c. |
| private static final String CLAT_PREFIX = "v4-"; |
| |
| // The network types on which we will start clatd, |
| // allowing clat only on networks for which we can support IPv6-only. |
| private static final int[] NETWORK_TYPES = { |
| ConnectivityManager.TYPE_MOBILE, |
| ConnectivityManager.TYPE_WIFI, |
| ConnectivityManager.TYPE_ETHERNET, |
| }; |
| |
| // The network states in which running clatd is supported. |
| private static final NetworkInfo.State[] NETWORK_STATES = { |
| NetworkInfo.State.CONNECTED, |
| NetworkInfo.State.SUSPENDED, |
| }; |
| |
| private final IDnsResolver mDnsResolver; |
| private final INetd mNetd; |
| private final INetworkManagementService mNMService; |
| |
| // The network we're running on, and its type. |
| private final NetworkAgentInfo mNetwork; |
| |
| private enum State { |
| IDLE, // start() not called. Base iface and stacked iface names are null. |
| DISCOVERING, // same as IDLE, except prefix discovery in progress. |
| STARTING, // start() called. Base iface and stacked iface names are known. |
| RUNNING, // start() called, and the stacked iface is known to be up. |
| } |
| |
| private IpPrefix mNat64Prefix; |
| private String mBaseIface; |
| private String mIface; |
| private Inet6Address mIPv6Address; |
| private State mState = State.IDLE; |
| |
| public Nat464Xlat(NetworkAgentInfo nai, INetd netd, IDnsResolver dnsResolver, |
| INetworkManagementService nmService) { |
| mDnsResolver = dnsResolver; |
| mNetd = netd; |
| mNMService = nmService; |
| mNetwork = nai; |
| } |
| |
| /** |
| * Whether to attempt 464xlat on this network. This is true for an IPv6-only network that is |
| * currently connected and where the NetworkAgent has not disabled 464xlat. It is the signal to |
| * enable NAT64 prefix discovery. |
| * |
| * @param network the NetworkAgentInfo corresponding to the network. |
| * @return true if the network requires clat, false otherwise. |
| */ |
| @VisibleForTesting |
| protected static boolean requiresClat(NetworkAgentInfo nai) { |
| // TODO: migrate to NetworkCapabilities.TRANSPORT_*. |
| final boolean supported = ArrayUtils.contains(NETWORK_TYPES, nai.networkInfo.getType()); |
| final boolean connected = ArrayUtils.contains(NETWORK_STATES, nai.networkInfo.getState()); |
| |
| // Only run clat on networks that have a global IPv6 address and don't have a native IPv4 |
| // address. |
| LinkProperties lp = nai.linkProperties; |
| final boolean isIpv6OnlyNetwork = (lp != null) && lp.hasGlobalIpv6Address() |
| && !lp.hasIpv4Address(); |
| |
| // If the network tells us it doesn't use clat, respect that. |
| final boolean skip464xlat = (nai.netAgentConfig() != null) |
| && nai.netAgentConfig().skip464xlat; |
| |
| return supported && connected && isIpv6OnlyNetwork && !skip464xlat; |
| } |
| |
| /** |
| * Whether the clat demon should be started on this network now. This is true if requiresClat is |
| * true and a NAT64 prefix has been discovered. |
| * |
| * @param nai the NetworkAgentInfo corresponding to the network. |
| * @return true if the network should start clat, false otherwise. |
| */ |
| @VisibleForTesting |
| protected static boolean shouldStartClat(NetworkAgentInfo nai) { |
| LinkProperties lp = nai.linkProperties; |
| return requiresClat(nai) && lp != null && lp.getNat64Prefix() != null; |
| } |
| |
| /** |
| * @return true if we have started prefix discovery and not yet stopped it (regardless of |
| * whether it is still running or has succeeded). |
| * A true result corresponds to internal states DISCOVERING, STARTING and RUNNING. |
| */ |
| public boolean isPrefixDiscoveryStarted() { |
| return mState == State.DISCOVERING || isStarted(); |
| } |
| |
| /** |
| * @return true if clatd has been started and has not yet stopped. |
| * A true result corresponds to internal states STARTING and RUNNING. |
| */ |
| public boolean isStarted() { |
| return (mState == State.STARTING || mState == State.RUNNING); |
| } |
| |
| /** |
| * @return true if clatd has been started but the stacked interface is not yet up. |
| */ |
| public boolean isStarting() { |
| return mState == State.STARTING; |
| } |
| |
| /** |
| * @return true if clatd has been started and the stacked interface is up. |
| */ |
| public boolean isRunning() { |
| return mState == State.RUNNING; |
| } |
| |
| /** |
| * Start clatd, register this Nat464Xlat as a network observer for the stacked interface, |
| * and set internal state. |
| */ |
| private void enterStartingState(String baseIface) { |
| try { |
| mNMService.registerObserver(this); |
| } catch (RemoteException e) { |
| Slog.e(TAG, "Can't register interface observer for clat on " + mNetwork.name()); |
| return; |
| } |
| |
| String addrStr = null; |
| try { |
| addrStr = mNetd.clatdStart(baseIface, mNat64Prefix.toString()); |
| } catch (RemoteException | ServiceSpecificException e) { |
| Slog.e(TAG, "Error starting clatd on " + baseIface + ": " + e); |
| } |
| mIface = CLAT_PREFIX + baseIface; |
| mBaseIface = baseIface; |
| mState = State.STARTING; |
| try { |
| mIPv6Address = (Inet6Address) InetAddresses.parseNumericAddress(addrStr); |
| } catch (ClassCastException | IllegalArgumentException | NullPointerException e) { |
| Slog.e(TAG, "Invalid IPv6 address " + addrStr); |
| } |
| } |
| |
| /** |
| * Enter running state just after getting confirmation that the stacked interface is up, and |
| * turn ND offload off if on WiFi. |
| */ |
| private void enterRunningState() { |
| mState = State.RUNNING; |
| } |
| |
| /** |
| * Unregister as a base observer for the stacked interface, and clear internal state. |
| */ |
| private void leaveStartedState() { |
| try { |
| mNMService.unregisterObserver(this); |
| } catch (RemoteException | IllegalStateException e) { |
| Slog.e(TAG, "Error unregistering clatd observer on " + mBaseIface + ": " + e); |
| } |
| mIface = null; |
| mBaseIface = null; |
| mState = State.IDLE; |
| if (requiresClat(mNetwork)) { |
| mState = State.DISCOVERING; |
| } else { |
| stopPrefixDiscovery(); |
| mState = State.IDLE; |
| } |
| } |
| |
| @VisibleForTesting |
| protected void start() { |
| if (isStarted()) { |
| Slog.e(TAG, "startClat: already started"); |
| return; |
| } |
| |
| if (mNetwork.linkProperties == null) { |
| Slog.e(TAG, "startClat: Can't start clat with null LinkProperties"); |
| return; |
| } |
| |
| String baseIface = mNetwork.linkProperties.getInterfaceName(); |
| if (baseIface == null) { |
| Slog.e(TAG, "startClat: Can't start clat on null interface"); |
| return; |
| } |
| // TODO: should we only do this if mNetd.clatdStart() succeeds? |
| Slog.i(TAG, "Starting clatd on " + baseIface); |
| enterStartingState(baseIface); |
| } |
| |
| @VisibleForTesting |
| protected void stop() { |
| if (!isStarted()) { |
| Slog.e(TAG, "stopClat: already stopped"); |
| return; |
| } |
| |
| Slog.i(TAG, "Stopping clatd on " + mBaseIface); |
| try { |
| mNetd.clatdStop(mBaseIface); |
| } catch (RemoteException | ServiceSpecificException e) { |
| Slog.e(TAG, "Error stopping clatd on " + mBaseIface + ": " + e); |
| } |
| |
| String iface = mIface; |
| boolean wasRunning = isRunning(); |
| |
| // Change state before updating LinkProperties. handleUpdateLinkProperties ends up calling |
| // fixupLinkProperties, and if at that time the state is still RUNNING, fixupLinkProperties |
| // would wrongly inform ConnectivityService that there is still a stacked interface. |
| leaveStartedState(); |
| |
| if (wasRunning) { |
| LinkProperties lp = new LinkProperties(mNetwork.linkProperties); |
| lp.removeStackedLink(iface); |
| mNetwork.connService().handleUpdateLinkProperties(mNetwork, lp); |
| } |
| } |
| |
| private void startPrefixDiscovery() { |
| try { |
| mDnsResolver.startPrefix64Discovery(getNetId()); |
| mState = State.DISCOVERING; |
| } catch (RemoteException | ServiceSpecificException e) { |
| Slog.e(TAG, "Error starting prefix discovery on netId " + getNetId() + ": " + e); |
| } |
| } |
| |
| private void stopPrefixDiscovery() { |
| try { |
| mDnsResolver.stopPrefix64Discovery(getNetId()); |
| } catch (RemoteException | ServiceSpecificException e) { |
| Slog.e(TAG, "Error stopping prefix discovery on netId " + getNetId() + ": " + e); |
| } |
| } |
| |
| /** |
| * Starts/stops NAT64 prefix discovery and clatd as necessary. |
| */ |
| public void update() { |
| // TODO: turn this class into a proper StateMachine. // http://b/126113090 |
| if (requiresClat(mNetwork)) { |
| if (!isPrefixDiscoveryStarted()) { |
| startPrefixDiscovery(); |
| } else if (shouldStartClat(mNetwork)) { |
| // NAT64 prefix detected. Start clatd. |
| // TODO: support the NAT64 prefix changing after it's been discovered. There is no |
| // need to support this at the moment because it cannot happen without changes to |
| // the Dns64Configuration code in netd. |
| start(); |
| } else { |
| // NAT64 prefix removed. Stop clatd and go back into DISCOVERING state. |
| stop(); |
| } |
| } else { |
| // Network no longer requires clat. Stop clat and prefix discovery. |
| if (isStarted()) { |
| stop(); |
| } else if (isPrefixDiscoveryStarted()) { |
| leaveStartedState(); |
| } |
| } |
| } |
| |
| public void setNat64Prefix(IpPrefix nat64Prefix) { |
| mNat64Prefix = nat64Prefix; |
| } |
| |
| /** |
| * Copies the stacked clat link in oldLp, if any, to the passed LinkProperties. |
| * This is necessary because the LinkProperties in mNetwork come from the transport layer, which |
| * has no idea that 464xlat is running on top of it. |
| */ |
| public void fixupLinkProperties(@NonNull LinkProperties oldLp, @NonNull LinkProperties lp) { |
| lp.setNat64Prefix(mNat64Prefix); |
| |
| if (!isRunning()) { |
| return; |
| } |
| if (lp.getAllInterfaceNames().contains(mIface)) { |
| return; |
| } |
| |
| Slog.d(TAG, "clatd running, updating NAI for " + mIface); |
| for (LinkProperties stacked: oldLp.getStackedLinks()) { |
| if (Objects.equals(mIface, stacked.getInterfaceName())) { |
| lp.addStackedLink(stacked); |
| return; |
| } |
| } |
| } |
| |
| private LinkProperties makeLinkProperties(LinkAddress clatAddress) { |
| LinkProperties stacked = new LinkProperties(); |
| stacked.setInterfaceName(mIface); |
| |
| // Although the clat interface is a point-to-point tunnel, we don't |
| // point the route directly at the interface because some apps don't |
| // understand routes without gateways (see, e.g., http://b/9597256 |
| // http://b/9597516). Instead, set the next hop of the route to the |
| // clat IPv4 address itself (for those apps, it doesn't matter what |
| // the IP of the gateway is, only that there is one). |
| RouteInfo ipv4Default = new RouteInfo( |
| new LinkAddress(Inet4Address.ANY, 0), |
| clatAddress.getAddress(), mIface); |
| stacked.addRoute(ipv4Default); |
| stacked.addLinkAddress(clatAddress); |
| return stacked; |
| } |
| |
| private LinkAddress getLinkAddress(String iface) { |
| try { |
| InterfaceConfiguration config = mNMService.getInterfaceConfig(iface); |
| return config.getLinkAddress(); |
| } catch (RemoteException | IllegalStateException e) { |
| Slog.e(TAG, "Error getting link properties: " + e); |
| return null; |
| } |
| } |
| |
| /** |
| * Adds stacked link on base link and transitions to RUNNING state. |
| */ |
| private void handleInterfaceLinkStateChanged(String iface, boolean up) { |
| // TODO: if we call start(), then stop(), then start() again, and the |
| // interfaceLinkStateChanged notification for the first start is delayed past the first |
| // stop, then the code becomes out of sync with system state and will behave incorrectly. |
| // |
| // This is not trivial to fix because: |
| // 1. It is not guaranteed that start() will eventually result in the interface coming up, |
| // because there could be an error starting clat (e.g., if the interface goes down before |
| // the packet socket can be bound). |
| // 2. If start is called multiple times, there is nothing in the interfaceLinkStateChanged |
| // notification that says which start() call the interface was created by. |
| // |
| // Once this code is converted to StateMachine, it will be possible to use deferMessage to |
| // ensure it stays in STARTING state until the interfaceLinkStateChanged notification fires, |
| // and possibly use a timeout (or provide some guarantees at the lower layer) to address #1. |
| if (!isStarting() || !up || !Objects.equals(mIface, iface)) { |
| return; |
| } |
| |
| LinkAddress clatAddress = getLinkAddress(iface); |
| if (clatAddress == null) { |
| Slog.e(TAG, "clatAddress was null for stacked iface " + iface); |
| return; |
| } |
| |
| Slog.i(TAG, String.format("interface %s is up, adding stacked link %s on top of %s", |
| mIface, mIface, mBaseIface)); |
| enterRunningState(); |
| LinkProperties lp = new LinkProperties(mNetwork.linkProperties); |
| lp.addStackedLink(makeLinkProperties(clatAddress)); |
| mNetwork.connService().handleUpdateLinkProperties(mNetwork, lp); |
| } |
| |
| /** |
| * Removes stacked link on base link and transitions to IDLE state. |
| */ |
| private void handleInterfaceRemoved(String iface) { |
| if (!Objects.equals(mIface, iface)) { |
| return; |
| } |
| if (!isRunning()) { |
| return; |
| } |
| |
| Slog.i(TAG, "interface " + iface + " removed"); |
| // If we're running, and the interface was removed, then we didn't call stop(), and it's |
| // likely that clatd crashed. Ensure we call stop() so we can start clatd again. Calling |
| // stop() will also update LinkProperties, and if clatd crashed, the LinkProperties update |
| // will cause ConnectivityService to call start() again. |
| stop(); |
| } |
| |
| @Override |
| public void interfaceLinkStateChanged(String iface, boolean up) { |
| mNetwork.handler().post(() -> { handleInterfaceLinkStateChanged(iface, up); }); |
| } |
| |
| @Override |
| public void interfaceRemoved(String iface) { |
| mNetwork.handler().post(() -> handleInterfaceRemoved(iface)); |
| } |
| |
| @Override |
| public String toString() { |
| return "mBaseIface: " + mBaseIface + ", mIface: " + mIface + ", mState: " + mState; |
| } |
| |
| @VisibleForTesting |
| protected int getNetId() { |
| return mNetwork.network.netId; |
| } |
| } |