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/*
* Copyright (C) 2017 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.networkstack.tethering;
import static android.net.ConnectivityManager.TYPE_BLUETOOTH;
import static android.net.ConnectivityManager.TYPE_ETHERNET;
import static android.net.ConnectivityManager.TYPE_MOBILE;
import static android.net.ConnectivityManager.TYPE_MOBILE_DUN;
import static android.net.ConnectivityManager.TYPE_MOBILE_HIPRI;
import static android.net.ConnectivityManager.TYPE_WIFI;
import static android.net.NetworkCapabilities.NET_CAPABILITY_DUN;
import static android.net.NetworkCapabilities.NET_CAPABILITY_INTERNET;
import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED;
import static android.net.NetworkCapabilities.NET_CAPABILITY_NOT_VPN;
import static android.net.NetworkCapabilities.TRANSPORT_CELLULAR;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.ConnectivityManager.NetworkCallback;
import android.net.IpPrefix;
import android.net.LinkProperties;
import android.net.Network;
import android.net.NetworkCapabilities;
import android.net.NetworkRequest;
import android.net.util.PrefixUtils;
import android.net.util.SharedLog;
import android.os.Handler;
import android.util.Log;
import android.util.SparseIntArray;
import com.android.internal.annotations.VisibleForTesting;
import com.android.internal.util.StateMachine;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Set;
/**
* A class to centralize all the network and link properties information
* pertaining to the current and any potential upstream network.
*
* The owner of UNM gets it to register network callbacks by calling the
* following methods :
* Calling #startTrackDefaultNetwork() to track the system default network.
* Calling #startObserveAllNetworks() to observe all networks. Listening all
* networks is necessary while the expression of preferred upstreams remains
* a list of legacy connectivity types. In future, this can be revisited.
* Calling #registerMobileNetworkRequest() to bring up mobile DUN/HIPRI network.
*
* The methods and data members of this class are only to be accessed and
* modified from the tethering master state machine thread. Any other
* access semantics would necessitate the addition of locking.
*
* TODO: Move upstream selection logic here.
*
* All callback methods are run on the same thread as the specified target
* state machine. This class does not require locking when accessed from this
* thread. Access from other threads is not advised.
*
* @hide
*/
public class UpstreamNetworkMonitor {
private static final String TAG = UpstreamNetworkMonitor.class.getSimpleName();
private static final boolean DBG = false;
private static final boolean VDBG = false;
public static final int EVENT_ON_CAPABILITIES = 1;
public static final int EVENT_ON_LINKPROPERTIES = 2;
public static final int EVENT_ON_LOST = 3;
public static final int NOTIFY_LOCAL_PREFIXES = 10;
// This value is used by deprecated preferredUpstreamIfaceTypes selection which is default
// disabled.
@VisibleForTesting
public static final int TYPE_NONE = -1;
private static final int CALLBACK_LISTEN_ALL = 1;
private static final int CALLBACK_DEFAULT_INTERNET = 2;
private static final int CALLBACK_MOBILE_REQUEST = 3;
private static final SparseIntArray sLegacyTypeToTransport = new SparseIntArray();
static {
sLegacyTypeToTransport.put(TYPE_MOBILE, NetworkCapabilities.TRANSPORT_CELLULAR);
sLegacyTypeToTransport.put(TYPE_MOBILE_DUN, NetworkCapabilities.TRANSPORT_CELLULAR);
sLegacyTypeToTransport.put(TYPE_MOBILE_HIPRI, NetworkCapabilities.TRANSPORT_CELLULAR);
sLegacyTypeToTransport.put(TYPE_WIFI, NetworkCapabilities.TRANSPORT_WIFI);
sLegacyTypeToTransport.put(TYPE_BLUETOOTH, NetworkCapabilities.TRANSPORT_BLUETOOTH);
sLegacyTypeToTransport.put(TYPE_ETHERNET, NetworkCapabilities.TRANSPORT_ETHERNET);
}
private final Context mContext;
private final SharedLog mLog;
private final StateMachine mTarget;
private final Handler mHandler;
private final int mWhat;
private final HashMap<Network, UpstreamNetworkState> mNetworkMap = new HashMap<>();
private HashSet<IpPrefix> mLocalPrefixes;
private ConnectivityManager mCM;
private EntitlementManager mEntitlementMgr;
private NetworkCallback mListenAllCallback;
private NetworkCallback mDefaultNetworkCallback;
private NetworkCallback mMobileNetworkCallback;
private boolean mDunRequired;
// Whether the current default upstream is mobile or not.
private boolean mIsDefaultCellularUpstream;
// The current system default network (not really used yet).
private Network mDefaultInternetNetwork;
// The current upstream network used for tethering.
private Network mTetheringUpstreamNetwork;
public UpstreamNetworkMonitor(Context ctx, StateMachine tgt, SharedLog log, int what) {
mContext = ctx;
mTarget = tgt;
mHandler = mTarget.getHandler();
mLog = log.forSubComponent(TAG);
mWhat = what;
mLocalPrefixes = new HashSet<>();
mIsDefaultCellularUpstream = false;
}
@VisibleForTesting
public UpstreamNetworkMonitor(
ConnectivityManager cm, StateMachine tgt, SharedLog log, int what) {
this((Context) null, tgt, log, what);
mCM = cm;
}
/**
* Tracking the system default network. This method should be called when system is ready.
*
* @param defaultNetworkRequest should be the same as ConnectivityService default request
* @param entitle a EntitlementManager object to communicate between EntitlementManager and
* UpstreamNetworkMonitor
*/
public void startTrackDefaultNetwork(NetworkRequest defaultNetworkRequest,
EntitlementManager entitle) {
// defaultNetworkRequest is not really a "request", just a way of tracking the system
// default network. It's guaranteed not to actually bring up any networks because it's
// the should be the same request as the ConnectivityService default request, and thus
// shares fate with it. We can't use registerDefaultNetworkCallback because it will not
// track the system default network if there is a VPN that applies to our UID.
if (mDefaultNetworkCallback == null) {
mDefaultNetworkCallback = new UpstreamNetworkCallback(CALLBACK_DEFAULT_INTERNET);
cm().requestNetwork(defaultNetworkRequest, mDefaultNetworkCallback, mHandler);
}
if (mEntitlementMgr == null) {
mEntitlementMgr = entitle;
}
}
/** Listen all networks. */
public void startObserveAllNetworks() {
stop();
final NetworkRequest listenAllRequest = new NetworkRequest.Builder()
.clearCapabilities().build();
mListenAllCallback = new UpstreamNetworkCallback(CALLBACK_LISTEN_ALL);
cm().registerNetworkCallback(listenAllRequest, mListenAllCallback, mHandler);
}
/**
* Stop tracking candidate tethering upstreams and release mobile network request.
* Note: this function is used when tethering is stopped because tethering do not need to
* choose upstream anymore. But it would not stop default network tracking because
* EntitlementManager may need to know default network to decide whether to request entitlement
* check even tethering is not active yet.
*/
public void stop() {
releaseMobileNetworkRequest();
releaseCallback(mListenAllCallback);
mListenAllCallback = null;
mTetheringUpstreamNetwork = null;
mNetworkMap.clear();
}
/** Setup or teardown DUN connection according to |dunRequired|. */
public void updateMobileRequiresDun(boolean dunRequired) {
final boolean valueChanged = (mDunRequired != dunRequired);
mDunRequired = dunRequired;
if (valueChanged && mobileNetworkRequested()) {
releaseMobileNetworkRequest();
registerMobileNetworkRequest();
}
}
/** Whether mobile network is requested. */
public boolean mobileNetworkRequested() {
return (mMobileNetworkCallback != null);
}
/** Request mobile network if mobile upstream is permitted. */
public void registerMobileNetworkRequest() {
if (!isCellularUpstreamPermitted()) {
mLog.i("registerMobileNetworkRequest() is not permitted");
releaseMobileNetworkRequest();
return;
}
if (mMobileNetworkCallback != null) {
mLog.e("registerMobileNetworkRequest() already registered");
return;
}
final NetworkRequest mobileUpstreamRequest;
if (mDunRequired) {
mobileUpstreamRequest = new NetworkRequest.Builder()
.addCapability(NET_CAPABILITY_DUN)
.removeCapability(NET_CAPABILITY_NOT_RESTRICTED)
.addTransportType(TRANSPORT_CELLULAR).build();
} else {
mobileUpstreamRequest = new NetworkRequest.Builder()
.addCapability(NET_CAPABILITY_INTERNET)
.addTransportType(TRANSPORT_CELLULAR).build();
}
// The existing default network and DUN callbacks will be notified.
// Therefore, to avoid duplicate notifications, we only register a no-op.
mMobileNetworkCallback = new UpstreamNetworkCallback(CALLBACK_MOBILE_REQUEST);
// The following use of the legacy type system cannot be removed until
// upstream selection no longer finds networks by legacy type.
// See also http://b/34364553 .
final int legacyType = mDunRequired ? TYPE_MOBILE_DUN : TYPE_MOBILE_HIPRI;
// TODO: Change the timeout from 0 (no onUnavailable callback) to some
// moderate callback timeout. This might be useful for updating some UI.
// Additionally, we log a message to aid in any subsequent debugging.
mLog.i("requesting mobile upstream network: " + mobileUpstreamRequest);
cm().requestNetwork(mobileUpstreamRequest, 0, legacyType, mHandler,
mMobileNetworkCallback);
}
/** Release mobile network request. */
public void releaseMobileNetworkRequest() {
if (mMobileNetworkCallback == null) return;
cm().unregisterNetworkCallback(mMobileNetworkCallback);
mMobileNetworkCallback = null;
}
// So many TODOs here, but chief among them is: make this functionality an
// integral part of this class such that whenever a higher priority network
// becomes available and useful we (a) file a request to keep it up as
// necessary and (b) change all upstream tracking state accordingly (by
// passing LinkProperties up to Tethering).
/**
* Select the first available network from |perferredTypes|.
*/
public UpstreamNetworkState selectPreferredUpstreamType(Iterable<Integer> preferredTypes) {
final TypeStatePair typeStatePair = findFirstAvailableUpstreamByType(
mNetworkMap.values(), preferredTypes, isCellularUpstreamPermitted());
mLog.log("preferred upstream type: " + typeStatePair.type);
switch (typeStatePair.type) {
case TYPE_MOBILE_DUN:
case TYPE_MOBILE_HIPRI:
// Tethering just selected mobile upstream in spite of the default network being
// not mobile. This can happen because of the priority list.
// Notify EntitlementManager to check permission for using mobile upstream.
if (!mIsDefaultCellularUpstream) {
mEntitlementMgr.maybeRunProvisioning();
}
// If we're on DUN, put our own grab on it.
registerMobileNetworkRequest();
break;
case TYPE_NONE:
// If we found NONE and mobile upstream is permitted we don't want to do this
// as we want any previous requests to keep trying to bring up something we can use.
if (!isCellularUpstreamPermitted()) releaseMobileNetworkRequest();
break;
default:
// If we've found an active upstream connection that's not DUN/HIPRI
// we should stop any outstanding DUN/HIPRI requests.
releaseMobileNetworkRequest();
break;
}
return typeStatePair.ns;
}
/**
* Get current preferred upstream network. If default network is cellular and DUN is required,
* preferred upstream would be DUN otherwise preferred upstream is the same as default network.
* Returns null if no current upstream is available.
*/
public UpstreamNetworkState getCurrentPreferredUpstream() {
final UpstreamNetworkState dfltState = (mDefaultInternetNetwork != null)
? mNetworkMap.get(mDefaultInternetNetwork)
: null;
if (isNetworkUsableAndNotCellular(dfltState)) return dfltState;
if (!isCellularUpstreamPermitted()) return null;
if (!mDunRequired) return dfltState;
// Find a DUN network. Note that code in Tethering causes a DUN request
// to be filed, but this might be moved into this class in future.
return findFirstDunNetwork(mNetworkMap.values());
}
/** Tell UpstreamNetworkMonitor which network is the current upstream of tethering. */
public void setCurrentUpstream(Network upstream) {
mTetheringUpstreamNetwork = upstream;
}
/** Return local prefixes. */
public Set<IpPrefix> getLocalPrefixes() {
return (Set<IpPrefix>) mLocalPrefixes.clone();
}
private boolean isCellularUpstreamPermitted() {
if (mEntitlementMgr != null) {
return mEntitlementMgr.isCellularUpstreamPermitted();
} else {
// This flow should only happens in testing.
return true;
}
}
private void handleAvailable(Network network) {
if (mNetworkMap.containsKey(network)) return;
if (VDBG) Log.d(TAG, "onAvailable for " + network);
mNetworkMap.put(network, new UpstreamNetworkState(null, null, network));
}
private void handleNetCap(Network network, NetworkCapabilities newNc) {
final UpstreamNetworkState prev = mNetworkMap.get(network);
if (prev == null || newNc.equals(prev.networkCapabilities)) {
// Ignore notifications about networks for which we have not yet
// received onAvailable() (should never happen) and any duplicate
// notifications (e.g. matching more than one of our callbacks).
return;
}
if (VDBG) {
Log.d(TAG, String.format("EVENT_ON_CAPABILITIES for %s: %s",
network, newNc));
}
mNetworkMap.put(network, new UpstreamNetworkState(
prev.linkProperties, newNc, network));
// TODO: If sufficient information is available to select a more
// preferable upstream, do so now and notify the target.
notifyTarget(EVENT_ON_CAPABILITIES, network);
}
private void handleLinkProp(Network network, LinkProperties newLp) {
final UpstreamNetworkState prev = mNetworkMap.get(network);
if (prev == null || newLp.equals(prev.linkProperties)) {
// Ignore notifications about networks for which we have not yet
// received onAvailable() (should never happen) and any duplicate
// notifications (e.g. matching more than one of our callbacks).
return;
}
if (VDBG) {
Log.d(TAG, String.format("EVENT_ON_LINKPROPERTIES for %s: %s",
network, newLp));
}
mNetworkMap.put(network, new UpstreamNetworkState(
newLp, prev.networkCapabilities, network));
// TODO: If sufficient information is available to select a more
// preferable upstream, do so now and notify the target.
notifyTarget(EVENT_ON_LINKPROPERTIES, network);
}
private void handleLost(Network network) {
// There are few TODOs within ConnectivityService's rematching code
// pertaining to spurious onLost() notifications.
//
// TODO: simplify this, probably if favor of code that:
// - selects a new upstream if mTetheringUpstreamNetwork has
// been lost (by any callback)
// - deletes the entry from the map only when the LISTEN_ALL
// callback gets notified.
if (!mNetworkMap.containsKey(network)) {
// Ignore loss of networks about which we had not previously
// learned any information or for which we have already processed
// an onLost() notification.
return;
}
if (VDBG) Log.d(TAG, "EVENT_ON_LOST for " + network);
// TODO: If sufficient information is available to select a more
// preferable upstream, do so now and notify the target. Likewise,
// if the current upstream network is gone, notify the target of the
// fact that we now have no upstream at all.
notifyTarget(EVENT_ON_LOST, mNetworkMap.remove(network));
}
private void recomputeLocalPrefixes() {
final HashSet<IpPrefix> localPrefixes = allLocalPrefixes(mNetworkMap.values());
if (!mLocalPrefixes.equals(localPrefixes)) {
mLocalPrefixes = localPrefixes;
notifyTarget(NOTIFY_LOCAL_PREFIXES, localPrefixes.clone());
}
}
// Fetch (and cache) a ConnectivityManager only if and when we need one.
private ConnectivityManager cm() {
if (mCM == null) {
// MUST call the String variant to be able to write unittests.
mCM = (ConnectivityManager) mContext.getSystemService(Context.CONNECTIVITY_SERVICE);
}
return mCM;
}
/**
* A NetworkCallback class that handles information of interest directly
* in the thread on which it is invoked. To avoid locking, this MUST be
* run on the same thread as the target state machine's handler.
*/
private class UpstreamNetworkCallback extends NetworkCallback {
private final int mCallbackType;
UpstreamNetworkCallback(int callbackType) {
mCallbackType = callbackType;
}
@Override
public void onAvailable(Network network) {
handleAvailable(network);
}
@Override
public void onCapabilitiesChanged(Network network, NetworkCapabilities newNc) {
if (mCallbackType == CALLBACK_DEFAULT_INTERNET) {
mDefaultInternetNetwork = network;
final boolean newIsCellular = isCellular(newNc);
if (mIsDefaultCellularUpstream != newIsCellular) {
mIsDefaultCellularUpstream = newIsCellular;
mEntitlementMgr.notifyUpstream(newIsCellular);
}
return;
}
handleNetCap(network, newNc);
}
@Override
public void onLinkPropertiesChanged(Network network, LinkProperties newLp) {
if (mCallbackType == CALLBACK_DEFAULT_INTERNET) return;
handleLinkProp(network, newLp);
// Any non-LISTEN_ALL callback will necessarily concern a network that will
// also match the LISTEN_ALL callback by construction of the LISTEN_ALL callback.
// So it's not useful to do this work for non-LISTEN_ALL callbacks.
if (mCallbackType == CALLBACK_LISTEN_ALL) {
recomputeLocalPrefixes();
}
}
@Override
public void onLost(Network network) {
if (mCallbackType == CALLBACK_DEFAULT_INTERNET) {
mDefaultInternetNetwork = null;
mIsDefaultCellularUpstream = false;
mEntitlementMgr.notifyUpstream(false);
return;
}
handleLost(network);
// Any non-LISTEN_ALL callback will necessarily concern a network that will
// also match the LISTEN_ALL callback by construction of the LISTEN_ALL callback.
// So it's not useful to do this work for non-LISTEN_ALL callbacks.
if (mCallbackType == CALLBACK_LISTEN_ALL) {
recomputeLocalPrefixes();
}
}
}
private void releaseCallback(NetworkCallback cb) {
if (cb != null) cm().unregisterNetworkCallback(cb);
}
private void notifyTarget(int which, Network network) {
notifyTarget(which, mNetworkMap.get(network));
}
private void notifyTarget(int which, Object obj) {
mTarget.sendMessage(mWhat, which, 0, obj);
}
private static class TypeStatePair {
public int type = TYPE_NONE;
public UpstreamNetworkState ns = null;
}
private static TypeStatePair findFirstAvailableUpstreamByType(
Iterable<UpstreamNetworkState> netStates, Iterable<Integer> preferredTypes,
boolean isCellularUpstreamPermitted) {
final TypeStatePair result = new TypeStatePair();
for (int type : preferredTypes) {
NetworkCapabilities nc;
try {
nc = networkCapabilitiesForType(type);
} catch (IllegalArgumentException iae) {
Log.e(TAG, "No NetworkCapabilities mapping for legacy type: " + type);
continue;
}
if (!isCellularUpstreamPermitted && isCellular(nc)) {
continue;
}
for (UpstreamNetworkState value : netStates) {
if (!nc.satisfiedByNetworkCapabilities(value.networkCapabilities)) {
continue;
}
result.type = type;
result.ns = value;
return result;
}
}
return result;
}
private static HashSet<IpPrefix> allLocalPrefixes(Iterable<UpstreamNetworkState> netStates) {
final HashSet<IpPrefix> prefixSet = new HashSet<>();
for (UpstreamNetworkState ns : netStates) {
final LinkProperties lp = ns.linkProperties;
if (lp == null) continue;
prefixSet.addAll(PrefixUtils.localPrefixesFrom(lp));
}
return prefixSet;
}
private static boolean isCellular(UpstreamNetworkState ns) {
return (ns != null) && isCellular(ns.networkCapabilities);
}
private static boolean isCellular(NetworkCapabilities nc) {
return (nc != null) && nc.hasTransport(TRANSPORT_CELLULAR)
&& nc.hasCapability(NET_CAPABILITY_NOT_VPN);
}
private static boolean hasCapability(UpstreamNetworkState ns, int netCap) {
return (ns != null) && (ns.networkCapabilities != null)
&& ns.networkCapabilities.hasCapability(netCap);
}
private static boolean isNetworkUsableAndNotCellular(UpstreamNetworkState ns) {
return (ns != null) && (ns.networkCapabilities != null) && (ns.linkProperties != null)
&& !isCellular(ns.networkCapabilities);
}
private static UpstreamNetworkState findFirstDunNetwork(
Iterable<UpstreamNetworkState> netStates) {
for (UpstreamNetworkState ns : netStates) {
if (isCellular(ns) && hasCapability(ns, NET_CAPABILITY_DUN)) return ns;
}
return null;
}
/**
* Given a legacy type (TYPE_WIFI, ...) returns the corresponding NetworkCapabilities instance.
* This function is used for deprecated legacy type and be disabled by default.
*/
@VisibleForTesting
public static NetworkCapabilities networkCapabilitiesForType(int type) {
final NetworkCapabilities.Builder builder = new NetworkCapabilities.Builder();
// Map from type to transports.
final int notFound = -1;
final int transport = sLegacyTypeToTransport.get(type, notFound);
if (transport == notFound) {
throw new IllegalArgumentException("unknown legacy type: " + type);
}
builder.addTransportType(transport);
if (type == TYPE_MOBILE_DUN) {
builder.addCapability(NetworkCapabilities.NET_CAPABILITY_DUN);
// DUN is restricted network, see NetworkCapabilities#FORCE_RESTRICTED_CAPABILITIES.
builder.removeCapability(NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED);
} else {
builder.addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET);
}
return builder.build();
}
}