/*
* 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.net.InterfaceConfiguration;
import android.net.ConnectivityManager;
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.util.Slog;
import com.android.internal.util.ArrayUtils;
import com.android.server.net.BaseNetworkObserver;
import java.net.Inet4Address;
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 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.
STARTING, // start() called. Base iface and stacked iface names are known.
RUNNING, // start() called, and the stacked iface is known to be up.
STOPPING; // stop() called, this Nat464Xlat is still registered as a network observer for
// the stacked interface.
}
private String mBaseIface;
private String mIface;
private State mState = State.IDLE;
public Nat464Xlat(INetworkManagementService nmService, NetworkAgentInfo nai) {
mNMService = nmService;
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) {
// 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());
// We only run clat on networks that don't have a native IPv4 address.
final boolean hasIPv4Address =
(nai.linkProperties != null) && nai.linkProperties.hasIPv4Address();
return supported && connected && !hasIPv4Address;
}
/**
* @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.IDLE;
}
/**
* @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;
}
/**
* @return true if clatd has been stopped.
*/
public boolean isStopping() {
return mState == State.STOPPING;
}
/**
* 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,
"startClat: Can't register interface observer for clat on " + mNetwork.name());
return;
}
try {
mNMService.startClatd(baseIface);
} catch(RemoteException|IllegalStateException e) {
Slog.e(TAG, "Error starting clatd on " + baseIface, e);
}
mIface = CLAT_PREFIX + baseIface;
mBaseIface = baseIface;
mState = State.STARTING;
}
/**
* 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;
}
/**
* Stop clatd, and turn ND offload on if it had been turned off.
*/
private void enterStoppingState() {
try {
mNMService.stopClatd(mBaseIface);
} catch(RemoteException|IllegalStateException e) {
Slog.e(TAG, "Error stopping clatd on " + mBaseIface, e);
}
mState = State.STOPPING;
}
/**
* Unregister as a base observer for the stacked interface, and clear internal state.
*/
private void enterIdleState() {
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;
}
/**
* Starts the clat daemon.
*/
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;
}
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 mNMService.startClatd() succeeds?
Slog.i(TAG, "Starting clatd on " + baseIface);
enterStartingState(baseIface);
}
/**
* Stops the clat daemon.
*/
public void stop() {
if (!isStarted()) {
return;
}
Slog.i(TAG, "Stopping clatd on " + mBaseIface);
boolean wasStarting = isStarting();
enterStoppingState();
if (wasStarting) {
enterIdleState();
}
}
/**
* 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(LinkProperties oldLp, LinkProperties lp) {
if (!isRunning()) {
return;
}
if (lp == null || 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) {
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() && !isStopping()) {
return;
}
Slog.i(TAG, "interface " + iface + " removed");
if (!isStopping()) {
// Ensure clatd is stopped if stop() has not been called: this likely means that clatd
// has crashed.
enterStoppingState();
}
enterIdleState();
LinkProperties lp = new LinkProperties(mNetwork.linkProperties);
lp.removeStackedLink(iface);
mNetwork.connService().handleUpdateLinkProperties(mNetwork, lp);
}
@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;
}
}