/*
* 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 static android.net.ConnectivityManager.TYPE_MOBILE;
import static android.net.ConnectivityManager.TYPE_WIFI;
import java.net.Inet4Address;
import android.content.Context;
import android.net.IConnectivityManager;
import android.net.InterfaceConfiguration;
import android.net.LinkAddress;
import android.net.LinkProperties;
import android.net.NetworkAgent;
import android.net.NetworkUtils;
import android.net.RouteInfo;
import android.os.Handler;
import android.os.Message;
import android.os.Messenger;
import android.os.INetworkManagementService;
import android.os.RemoteException;
import android.util.Slog;
import com.android.server.net.BaseNetworkObserver;
/**
* @hide
*
* Class to manage a 464xlat CLAT daemon.
*/
public class Nat464Xlat extends BaseNetworkObserver {
private static final String TAG = "Nat464Xlat";
// This must match the interface prefix in clatd.c.
private static final String CLAT_PREFIX = "v4-";
private final INetworkManagementService mNMService;
// ConnectivityService Handler for LinkProperties updates.
private final Handler mHandler;
// The network we're running on, and its type.
private final NetworkAgentInfo mNetwork;
// Internal state variables.
//
// The possible states are:
// - Idle: start() not called. Everything is null.
// - Starting: start() called. Interfaces are non-null. isStarted() returns true.
// mIsRunning is false.
// - Running: start() called, and interfaceLinkStateChanged() told us that mIface is up.
// mIsRunning is true.
//
// Once mIface is non-null and isStarted() is true, methods called by ConnectivityService on
// its handler thread must not modify any internal state variables; they are only updated by the
// interface observers, called on the notification threads.
private String mBaseIface;
private String mIface;
private boolean mIsRunning;
public Nat464Xlat(
Context context, INetworkManagementService nmService,
Handler handler, NetworkAgentInfo nai) {
mNMService = nmService;
mHandler = handler;
mNetwork = nai;
}
/**
* Determines whether a network requires clat.
* @param network the NetworkAgentInfo corresponding to the network.
* @return true if the network requires clat, false otherwise.
*/
public static boolean requiresClat(NetworkAgentInfo nai) {
final int netType = nai.networkInfo.getType();
final boolean connected = nai.networkInfo.isConnected();
final boolean hasIPv4Address =
(nai.linkProperties != null) ? nai.linkProperties.hasIPv4Address() : false;
// Only support clat on mobile and wifi for now, because these are the only IPv6-only
// networks we can connect to.
return connected && !hasIPv4Address && (netType == TYPE_MOBILE || netType == TYPE_WIFI);
}
/**
* Determines whether clatd is started. Always true, except a) if start has not yet been called,
* or b) if our interface was removed.
*/
public boolean isStarted() {
return mIface != null;
}
/**
* Clears internal state. Must not be called by ConnectivityService.
*/
private void clear() {
mIface = null;
mBaseIface = null;
mIsRunning = false;
}
/**
* Starts the clat daemon. Called by ConnectivityService on the handler thread.
*/
public 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;
}
try {
mNMService.registerObserver(this);
} catch(RemoteException e) {
Slog.e(TAG, "startClat: Can't register interface observer for clat on " + mNetwork);
return;
}
mBaseIface = mNetwork.linkProperties.getInterfaceName();
if (mBaseIface == null) {
Slog.e(TAG, "startClat: Can't start clat on null interface");
return;
}
mIface = CLAT_PREFIX + mBaseIface;
// From now on, isStarted() will return true.
Slog.i(TAG, "Starting clatd on " + mBaseIface);
try {
mNMService.startClatd(mBaseIface);
} catch(RemoteException|IllegalStateException e) {
Slog.e(TAG, "Error starting clatd: " + e);
}
}
/**
* Stops the clat daemon. Called by ConnectivityService on the handler thread.
*/
public void stop() {
if (isStarted()) {
Slog.i(TAG, "Stopping clatd");
try {
mNMService.stopClatd(mBaseIface);
} catch(RemoteException|IllegalStateException e) {
Slog.e(TAG, "Error stopping clatd: " + e);
}
// When clatd stops and its interface is deleted, interfaceRemoved() will notify
// ConnectivityService and call clear().
} else {
Slog.e(TAG, "clatd: already stopped");
}
}
private void updateConnectivityService(LinkProperties lp) {
Message msg = mHandler.obtainMessage(NetworkAgent.EVENT_NETWORK_PROPERTIES_CHANGED, lp);
msg.replyTo = mNetwork.messenger;
Slog.i(TAG, "sending message to ConnectivityService: " + msg);
msg.sendToTarget();
}
/**
* Copies the stacked clat link in oldLp, if any, to the LinkProperties in mNetwork.
* 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(LinkProperties oldLp) {
if (mNetwork.clatd != null &&
mIsRunning &&
mNetwork.linkProperties != null &&
!mNetwork.linkProperties.getAllInterfaceNames().contains(mIface)) {
Slog.d(TAG, "clatd running, updating NAI for " + mIface);
for (LinkProperties stacked: oldLp.getStackedLinks()) {
if (mIface.equals(stacked.getInterfaceName())) {
mNetwork.linkProperties.addStackedLink(stacked);
break;
}
}
}
}
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;
}
}
private void maybeSetIpv6NdOffload(String iface, boolean on) {
if (mNetwork.networkInfo.getType() != TYPE_WIFI) {
return;
}
try {
Slog.d(TAG, (on ? "En" : "Dis") + "abling ND offload on " + iface);
mNMService.setInterfaceIpv6NdOffload(iface, on);
} catch(RemoteException|IllegalStateException e) {
Slog.w(TAG, "Changing IPv6 ND offload on " + iface + "failed: " + e);
}
}
@Override
public void interfaceLinkStateChanged(String iface, boolean up) {
// Called by the InterfaceObserver on its own thread, so can race with stop().
if (isStarted() && up && mIface.equals(iface)) {
Slog.i(TAG, "interface " + iface + " is up, mIsRunning " + mIsRunning + "->true");
if (!mIsRunning) {
LinkAddress clatAddress = getLinkAddress(iface);
if (clatAddress == null) {
return;
}
mIsRunning = true;
maybeSetIpv6NdOffload(mBaseIface, false);
LinkProperties lp = new LinkProperties(mNetwork.linkProperties);
lp.addStackedLink(makeLinkProperties(clatAddress));
Slog.i(TAG, "Adding stacked link " + mIface + " on top of " + mBaseIface);
updateConnectivityService(lp);
}
}
}
@Override
public void interfaceRemoved(String iface) {
if (isStarted() && mIface.equals(iface)) {
Slog.i(TAG, "interface " + iface + " removed, mIsRunning " + mIsRunning + "->false");
if (mIsRunning) {
// The interface going away likely means clatd has crashed. Ask netd to stop it,
// because otherwise when we try to start it again on the same base interface netd
// will complain that it's already started.
//
// Note that this method can be called by the interface observer at the same time
// that ConnectivityService calls stop(). In this case, the second call to
// stopClatd() will just throw IllegalStateException, which we'll ignore.
try {
mNMService.unregisterObserver(this);
mNMService.stopClatd(mBaseIface);
} catch (RemoteException|IllegalStateException e) {
// Well, we tried.
}
maybeSetIpv6NdOffload(mBaseIface, true);
LinkProperties lp = new LinkProperties(mNetwork.linkProperties);
lp.removeStackedLink(mIface);
clear();
updateConnectivityService(lp);
}
}
}
}
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