/*
* Copyright (C) 2014 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.NetworkCapabilities.NET_CAPABILITY_VALIDATED;
import android.content.Context;
import android.net.LinkProperties;
import android.net.Network;
import android.net.NetworkCapabilities;
import android.net.NetworkInfo;
import android.net.NetworkMisc;
import android.net.NetworkRequest;
import android.net.NetworkState;
import android.os.Handler;
import android.os.INetworkManagementService;
import android.os.Messenger;
import android.os.RemoteException;
import android.os.SystemClock;
import android.util.Log;
import android.util.SparseArray;
import com.android.internal.util.AsyncChannel;
import com.android.internal.util.WakeupMessage;
import com.android.server.ConnectivityService;
import com.android.server.connectivity.NetworkMonitor;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Objects;
import java.util.SortedSet;
import java.util.TreeSet;
/**
* A bag class used by ConnectivityService for holding a collection of most recent
* information published by a particular NetworkAgent as well as the
* AsyncChannel/messenger for reaching that NetworkAgent and lists of NetworkRequests
* interested in using it. Default sort order is descending by score.
*/
// States of a network:
// --------------------
// 1. registered, uncreated, disconnected, unvalidated
// This state is entered when a NetworkFactory registers a NetworkAgent in any state except
// the CONNECTED state.
// 2. registered, uncreated, connecting, unvalidated
// This state is entered when a registered NetworkAgent for a VPN network transitions to the
// CONNECTING state (TODO: go through this state for every network, not just VPNs).
// ConnectivityService will tell netd to create the network early in order to add extra UID
// routing rules referencing the netID. These rules need to be in place before the network is
// connected to avoid racing against client apps trying to connect to a half-setup network.
// 3. registered, uncreated, connected, unvalidated
// This state is entered when a registered NetworkAgent transitions to the CONNECTED state.
// ConnectivityService will tell netd to create the network if it was not already created, and
// immediately transition to state #4.
// 4. registered, created, connected, unvalidated
// If this network can satisfy the default NetworkRequest, then NetworkMonitor will
// probe for Internet connectivity.
// If this network cannot satisfy the default NetworkRequest, it will immediately be
// transitioned to state #5.
// A network may remain in this state if NetworkMonitor fails to find Internet connectivity,
// for example:
// a. a captive portal is present, or
// b. a WiFi router whose Internet backhaul is down, or
// c. a wireless connection stops transfering packets temporarily (e.g. device is in elevator
// or tunnel) but does not disconnect from the AP/cell tower, or
// d. a stand-alone device offering a WiFi AP without an uplink for configuration purposes.
// 5. registered, created, connected, validated
//
// The device's default network connection:
// ----------------------------------------
// Networks in states #4 and #5 may be used as a device's default network connection if they
// satisfy the default NetworkRequest.
// A network, that satisfies the default NetworkRequest, in state #5 should always be chosen
// in favor of a network, that satisfies the default NetworkRequest, in state #4.
// When deciding between two networks, that both satisfy the default NetworkRequest, to select
// for the default network connection, the one with the higher score should be chosen.
//
// When a network disconnects:
// ---------------------------
// If a network's transport disappears, for example:
// a. WiFi turned off, or
// b. cellular data turned off, or
// c. airplane mode is turned on, or
// d. a wireless connection disconnects from AP/cell tower entirely (e.g. device is out of range
// of AP for an extended period of time, or switches to another AP without roaming)
// then that network can transition from any state (#1-#5) to unregistered. This happens by
// the transport disconnecting their NetworkAgent's AsyncChannel with ConnectivityManager.
// ConnectivityService also tells netd to destroy the network.
//
// When ConnectivityService disconnects a network:
// -----------------------------------------------
// If a network has no chance of satisfying any requests (even if it were to become validated
// and enter state #5), ConnectivityService will disconnect the NetworkAgent's AsyncChannel.
//
// If the network was satisfying a foreground NetworkRequest (i.e. had been the highest scoring that
// satisfied the NetworkRequest's constraints), but is no longer the highest scoring network for any
// foreground NetworkRequest, then there will be a 30s pause to allow network communication to be
// wrapped up rather than abruptly terminated. During this pause the network is said to be
// "lingering". During this pause if the network begins satisfying a foreground NetworkRequest,
// ConnectivityService will cancel the future disconnection of the NetworkAgent's AsyncChannel, and
// the network is no longer considered "lingering". After the linger timer expires, if the network
// is satisfying one or more background NetworkRequests it is kept up in the background. If it is
// not, ConnectivityService disconnects the NetworkAgent's AsyncChannel.
public class NetworkAgentInfo implements Comparable<NetworkAgentInfo> {
public NetworkInfo networkInfo;
// This Network object should always be used if possible, so as to encourage reuse of the
// enclosed socket factory and connection pool. Avoid creating other Network objects.
// This Network object is always valid.
public final Network network;
public LinkProperties linkProperties;
// This should only be modified via ConnectivityService.updateCapabilities().
public NetworkCapabilities networkCapabilities;
public final NetworkMonitor networkMonitor;
public final NetworkMisc networkMisc;
// Indicates if netd has been told to create this Network. From this point on the appropriate
// routing rules are setup and routes are added so packets can begin flowing over the Network.
// This is a sticky bit; once set it is never cleared.
public boolean created;
// Set to true after the first time this network is marked as CONNECTED. Once set, the network
// shows up in API calls, is able to satisfy NetworkRequests and can become the default network.
// This is a sticky bit; once set it is never cleared.
public boolean everConnected;
// Set to true if this Network successfully passed validation or if it did not satisfy the
// default NetworkRequest in which case validation will not be attempted.
// This is a sticky bit; once set it is never cleared even if future validation attempts fail.
public boolean everValidated;
// The result of the last validation attempt on this network (true if validated, false if not).
public boolean lastValidated;
// If true, becoming unvalidated will lower the network's score. This is only meaningful if the
// system is configured not to do this for certain networks, e.g., if the
// config_networkAvoidBadWifi option is set to 0 and the user has not overridden that via
// Settings.Global.NETWORK_AVOID_BAD_WIFI.
public boolean avoidUnvalidated;
// Whether a captive portal was ever detected on this network.
// This is a sticky bit; once set it is never cleared.
public boolean everCaptivePortalDetected;
// Whether a captive portal was found during the last network validation attempt.
public boolean lastCaptivePortalDetected;
// Networks are lingered when they become unneeded as a result of their NetworkRequests being
// satisfied by a higher-scoring network. so as to allow communication to wrap up before the
// network is taken down. This usually only happens to the default network. Lingering ends with
// either the linger timeout expiring and the network being taken down, or the network
// satisfying a request again.
public static class LingerTimer implements Comparable<LingerTimer> {
public final NetworkRequest request;
public final long expiryMs;
public LingerTimer(NetworkRequest request, long expiryMs) {
this.request = request;
this.expiryMs = expiryMs;
}
public boolean equals(Object o) {
if (!(o instanceof LingerTimer)) return false;
LingerTimer other = (LingerTimer) o;
return (request.requestId == other.request.requestId) && (expiryMs == other.expiryMs);
}
public int hashCode() {
return Objects.hash(request.requestId, expiryMs);
}
public int compareTo(LingerTimer other) {
return (expiryMs != other.expiryMs) ?
Long.compare(expiryMs, other.expiryMs) :
Integer.compare(request.requestId, other.request.requestId);
}
public String toString() {
return String.format("%s, expires %dms", request.toString(),
expiryMs - SystemClock.elapsedRealtime());
}
}
/**
* Inform ConnectivityService that the network LINGER period has
* expired.
* obj = this NetworkAgentInfo
*/
public static final int EVENT_NETWORK_LINGER_COMPLETE = 1001;
// All linger timers for this network, sorted by expiry time. A linger timer is added whenever
// a request is moved to a network with a better score, regardless of whether the network is or
// was lingering or not.
// TODO: determine if we can replace this with a smaller or unsorted data structure. (e.g.,
// SparseLongArray) combined with the timestamp of when the last timer is scheduled to fire.
private final SortedSet<LingerTimer> mLingerTimers = new TreeSet<>();
// For fast lookups. Indexes into mLingerTimers by request ID.
private final SparseArray<LingerTimer> mLingerTimerForRequest = new SparseArray<>();
// Linger expiry timer. Armed whenever mLingerTimers is non-empty, regardless of whether the
// network is lingering or not. Always set to the expiry of the LingerTimer that expires last.
// When the timer fires, all linger state is cleared, and if the network has no requests, it is
// torn down.
private WakeupMessage mLingerMessage;
// Linger expiry. Holds the expiry time of the linger timer, or 0 if the timer is not armed.
private long mLingerExpiryMs;
// Whether the network is lingering or not. Must be maintained separately from the above because
// it depends on the state of other networks and requests, which only ConnectivityService knows.
// (Example: we don't linger a network if it would become the best for a NetworkRequest if it
// validated).
private boolean mLingering;
// This represents the last score received from the NetworkAgent.
private int currentScore;
// The list of NetworkRequests being satisfied by this Network.
private final SparseArray<NetworkRequest> mNetworkRequests = new SparseArray<>();
// How many of the satisfied requests are actual requests and not listens.
private int mNumRequestNetworkRequests = 0;
// How many of the satisfied requests are of type BACKGROUND_REQUEST.
private int mNumBackgroundNetworkRequests = 0;
public final Messenger messenger;
public final AsyncChannel asyncChannel;
// Used by ConnectivityService to keep track of 464xlat.
public Nat464Xlat clatd;
private static final String TAG = ConnectivityService.class.getSimpleName();
private static final boolean VDBG = false;
private final ConnectivityService mConnService;
private final Context mContext;
private final Handler mHandler;
public NetworkAgentInfo(Messenger messenger, AsyncChannel ac, Network net, NetworkInfo info,
LinkProperties lp, NetworkCapabilities nc, int score, Context context, Handler handler,
NetworkMisc misc, NetworkRequest defaultRequest, ConnectivityService connService) {
this.messenger = messenger;
asyncChannel = ac;
network = net;
networkInfo = info;
linkProperties = lp;
networkCapabilities = nc;
currentScore = score;
mConnService = connService;
mContext = context;
mHandler = handler;
networkMonitor = mConnService.createNetworkMonitor(context, handler, this, defaultRequest);
networkMisc = misc;
}
public ConnectivityService connService() {
return mConnService;
}
public Handler handler() {
return mHandler;
}
public Network network() {
return network;
}
// Functions for manipulating the requests satisfied by this network.
//
// These functions must only called on ConnectivityService's main thread.
private static final boolean ADD = true;
private static final boolean REMOVE = false;
private void updateRequestCounts(boolean add, NetworkRequest request) {
int delta = add ? +1 : -1;
switch (request.type) {
case REQUEST:
mNumRequestNetworkRequests += delta;
break;
case BACKGROUND_REQUEST:
mNumRequestNetworkRequests += delta;
mNumBackgroundNetworkRequests += delta;
break;
case TRACK_DEFAULT:
case LISTEN:
break;
case NONE:
default:
Log.wtf(TAG, "Unhandled request type " + request.type);
break;
}
}
/**
* Add {@code networkRequest} to this network as it's satisfied by this network.
* @return true if {@code networkRequest} was added or false if {@code networkRequest} was
* already present.
*/
public boolean addRequest(NetworkRequest networkRequest) {
NetworkRequest existing = mNetworkRequests.get(networkRequest.requestId);
if (existing == networkRequest) return false;
if (existing != null) {
// Should only happen if the requestId wraps. If that happens lots of other things will
// be broken as well.
Log.wtf(TAG, String.format("Duplicate requestId for %s and %s on %s",
networkRequest, existing, name()));
updateRequestCounts(REMOVE, existing);
}
mNetworkRequests.put(networkRequest.requestId, networkRequest);
updateRequestCounts(ADD, networkRequest);
return true;
}
/**
* Remove the specified request from this network.
*/
public void removeRequest(int requestId) {
NetworkRequest existing = mNetworkRequests.get(requestId);
if (existing == null) return;
updateRequestCounts(REMOVE, existing);
mNetworkRequests.remove(requestId);
if (existing.isRequest()) {
unlingerRequest(existing);
}
}
/**
* Returns whether this network is currently satisfying the request with the specified ID.
*/
public boolean isSatisfyingRequest(int id) {
return mNetworkRequests.get(id) != null;
}
/**
* Returns the request at the specified position in the list of requests satisfied by this
* network.
*/
public NetworkRequest requestAt(int index) {
return mNetworkRequests.valueAt(index);
}
/**
* Returns the number of requests currently satisfied by this network for which
* {@link android.net.NetworkRequest#isRequest} returns {@code true}.
*/
public int numRequestNetworkRequests() {
return mNumRequestNetworkRequests;
}
/**
* Returns the number of requests currently satisfied by this network of type
* {@link android.net.NetworkRequest.Type.BACKGROUND_REQUEST}.
*/
public int numBackgroundNetworkRequests() {
return mNumBackgroundNetworkRequests;
}
/**
* Returns the number of foreground requests currently satisfied by this network.
*/
public int numForegroundNetworkRequests() {
return mNumRequestNetworkRequests - mNumBackgroundNetworkRequests;
}
/**
* Returns the number of requests of any type currently satisfied by this network.
*/
public int numNetworkRequests() {
return mNetworkRequests.size();
}
/**
* Returns whether the network is a background network. A network is a background network if it
* does not have the NET_CAPABILITY_FOREGROUND capability, which implies it is satisfying no
* foreground request, is not lingering (i.e. kept for a while after being outscored), and is
* not a speculative network (i.e. kept pending validation when validation would have it
* outscore another foreground network). That implies it is being kept up by some background
* request (otherwise it would be torn down), maybe the mobile always-on request.
*/
public boolean isBackgroundNetwork() {
return !isVPN() && numForegroundNetworkRequests() == 0 && mNumBackgroundNetworkRequests > 0
&& !isLingering();
}
/**
* Returns whether this network is currently suspended. A network is suspended if it is still
* connected but data temporarily fails to transfer. See {@link NetworkInfo.State#SUSPENDED}
* and {@link NetworkCapabilities#NET_CAPABILITY_NOT_SUSPENDED}.
*/
public boolean isSuspended() {
return networkInfo.getState() == NetworkInfo.State.SUSPENDED;
}
// Does this network satisfy request?
public boolean satisfies(NetworkRequest request) {
return created &&
request.networkCapabilities.satisfiedByNetworkCapabilities(networkCapabilities);
}
public boolean satisfiesImmutableCapabilitiesOf(NetworkRequest request) {
return created &&
request.networkCapabilities.satisfiedByImmutableNetworkCapabilities(
networkCapabilities);
}
public boolean isVPN() {
return networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_VPN);
}
private int getCurrentScore(boolean pretendValidated) {
// TODO: We may want to refactor this into a NetworkScore class that takes a base score from
// the NetworkAgent and signals from the NetworkAgent and uses those signals to modify the
// score. The NetworkScore class would provide a nice place to centralize score constants
// so they are not scattered about the transports.
// If this network is explicitly selected and the user has decided to use it even if it's
// unvalidated, give it the maximum score. Also give it the maximum score if it's explicitly
// selected and we're trying to see what its score could be. This ensures that we don't tear
// down an explicitly selected network before the user gets a chance to prefer it when
// a higher-scoring network (e.g., Ethernet) is available.
if (networkMisc.explicitlySelected && (networkMisc.acceptUnvalidated || pretendValidated)) {
return ConnectivityConstants.MAXIMUM_NETWORK_SCORE;
}
int score = currentScore;
if (!lastValidated && !pretendValidated && !ignoreWifiUnvalidationPenalty()) {
score -= ConnectivityConstants.UNVALIDATED_SCORE_PENALTY;
}
if (score < 0) score = 0;
return score;
}
// Return true on devices configured to ignore score penalty for wifi networks
// that become unvalidated (b/31075769).
private boolean ignoreWifiUnvalidationPenalty() {
boolean isWifi = networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_WIFI) &&
networkCapabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET);
boolean avoidBadWifi = mConnService.avoidBadWifi() || avoidUnvalidated;
return isWifi && !avoidBadWifi && everValidated;
}
// Get the current score for this Network. This may be modified from what the
// NetworkAgent sent, as it has modifiers applied to it.
public int getCurrentScore() {
return getCurrentScore(false);
}
// Get the current score for this Network as if it was validated. This may be modified from
// what the NetworkAgent sent, as it has modifiers applied to it.
public int getCurrentScoreAsValidated() {
return getCurrentScore(true);
}
public void setCurrentScore(int newScore) {
currentScore = newScore;
}
public NetworkState getNetworkState() {
synchronized (this) {
// Network objects are outwardly immutable so there is no point in duplicating.
// Duplicating also precludes sharing socket factories and connection pools.
final String subscriberId = (networkMisc != null) ? networkMisc.subscriberId : null;
return new NetworkState(new NetworkInfo(networkInfo),
new LinkProperties(linkProperties),
new NetworkCapabilities(networkCapabilities), network, subscriberId, null);
}
}
/**
* Sets the specified request to linger on this network for the specified time. Called by
* ConnectivityService when the request is moved to another network with a higher score.
*/
public void lingerRequest(NetworkRequest request, long now, long duration) {
if (mLingerTimerForRequest.get(request.requestId) != null) {
// Cannot happen. Once a request is lingering on a particular network, we cannot
// re-linger it unless that network becomes the best for that request again, in which
// case we should have unlingered it.
Log.wtf(TAG, this.name() + ": request " + request.requestId + " already lingered");
}
final long expiryMs = now + duration;
LingerTimer timer = new LingerTimer(request, expiryMs);
if (VDBG) Log.d(TAG, "Adding LingerTimer " + timer + " to " + this.name());
mLingerTimers.add(timer);
mLingerTimerForRequest.put(request.requestId, timer);
}
/**
* Cancel lingering. Called by ConnectivityService when a request is added to this network.
* Returns true if the given request was lingering on this network, false otherwise.
*/
public boolean unlingerRequest(NetworkRequest request) {
LingerTimer timer = mLingerTimerForRequest.get(request.requestId);
if (timer != null) {
if (VDBG) Log.d(TAG, "Removing LingerTimer " + timer + " from " + this.name());
mLingerTimers.remove(timer);
mLingerTimerForRequest.remove(request.requestId);
return true;
}
return false;
}
public long getLingerExpiry() {
return mLingerExpiryMs;
}
public void updateLingerTimer() {
long newExpiry = mLingerTimers.isEmpty() ? 0 : mLingerTimers.last().expiryMs;
if (newExpiry == mLingerExpiryMs) return;
// Even if we're going to reschedule the timer, cancel it first. This is because the
// semantics of WakeupMessage guarantee that if cancel is called then the alarm will
// never call its callback (handleLingerComplete), even if it has already fired.
// WakeupMessage makes no such guarantees about rescheduling a message, so if mLingerMessage
// has already been dispatched, rescheduling to some time in the future it won't stop it
// from calling its callback immediately.
if (mLingerMessage != null) {
mLingerMessage.cancel();
mLingerMessage = null;
}
if (newExpiry > 0) {
mLingerMessage = mConnService.makeWakeupMessage(
mContext, mHandler,
"NETWORK_LINGER_COMPLETE." + network.netId,
EVENT_NETWORK_LINGER_COMPLETE, this);
mLingerMessage.schedule(newExpiry);
}
mLingerExpiryMs = newExpiry;
}
public void linger() {
mLingering = true;
}
public void unlinger() {
mLingering = false;
}
public boolean isLingering() {
return mLingering;
}
public void clearLingerState() {
if (mLingerMessage != null) {
mLingerMessage.cancel();
mLingerMessage = null;
}
mLingerTimers.clear();
mLingerTimerForRequest.clear();
updateLingerTimer(); // Sets mLingerExpiryMs, cancels and nulls out mLingerMessage.
mLingering = false;
}
public void dumpLingerTimers(PrintWriter pw) {
for (LingerTimer timer : mLingerTimers) { pw.println(timer); }
}
public void updateClat(INetworkManagementService netd) {
if (Nat464Xlat.requiresClat(this)) {
maybeStartClat(netd);
} else {
maybeStopClat();
}
}
/** Ensure clat has started for this network. */
public void maybeStartClat(INetworkManagementService netd) {
if (clatd != null && clatd.isStarted()) {
return;
}
clatd = new Nat464Xlat(netd, this);
clatd.start();
}
/** Ensure clat has stopped for this network. */
public void maybeStopClat() {
if (clatd == null) {
return;
}
clatd.stop();
clatd = null;
}
public String toString() {
return "NetworkAgentInfo{ ni{" + networkInfo + "} " +
"network{" + network + "} nethandle{" + network.getNetworkHandle() + "} " +
"lp{" + linkProperties + "} " +
"nc{" + networkCapabilities + "} Score{" + getCurrentScore() + "} " +
"everValidated{" + everValidated + "} lastValidated{" + lastValidated + "} " +
"created{" + created + "} lingering{" + isLingering() + "} " +
"explicitlySelected{" + networkMisc.explicitlySelected + "} " +
"acceptUnvalidated{" + networkMisc.acceptUnvalidated + "} " +
"everCaptivePortalDetected{" + everCaptivePortalDetected + "} " +
"lastCaptivePortalDetected{" + lastCaptivePortalDetected + "} " +
"clat{" + clatd + "} " +
"}";
}
public String name() {
return "NetworkAgentInfo [" + networkInfo.getTypeName() + " (" +
networkInfo.getSubtypeName() + ") - " + Objects.toString(network) + "]";
}
// Enables sorting in descending order of score.
@Override
public int compareTo(NetworkAgentInfo other) {
return other.getCurrentScore() - getCurrentScore();
}
}