/* * 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.Messenger; 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 { 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 { 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 mLingerTimers = new TreeSet<>(); // For fast lookups. Indexes into mLingerTimers by request ID. private final SparseArray 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; // Penalty applied to scores of Networks that have not been validated. private static final int UNVALIDATED_SCORE_PENALTY = 40; // Score for explicitly connected network. // // This ensures that a) the explicitly selected network is never trumped by anything else, and // b) the explicitly selected network is never torn down. private static final int MAXIMUM_NETWORK_SCORE = 100; // The list of NetworkRequests being satisfied by this Network. private final SparseArray 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; } // 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: case TRACK_DEFAULT: mNumRequestNetworkRequests += delta; break; case BACKGROUND_REQUEST: mNumRequestNetworkRequests += delta; mNumBackgroundNetworkRequests += delta; break; 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 * is satisfying no foreground requests and at least one background request. (If it did not have * a background request, it would be a speculative network that is only being kept up because * it might satisfy a request if it validated). */ public boolean isBackgroundNetwork() { return !isVPN() && numForegroundNetworkRequests() == 0 && mNumBackgroundNetworkRequests > 0; } // 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 MAXIMUM_NETWORK_SCORE; } int score = currentScore; if (!lastValidated && !pretendValidated && !ignoreWifiUnvalidationPenalty()) { score -= 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 to 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 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 + "} " + "}"; } public String name() { return "NetworkAgentInfo [" + networkInfo.getTypeName() + " (" + networkInfo.getSubtypeName() + ") - " + (network == null ? "null" : network.toString()) + "]"; } // Enables sorting in descending order of score. @Override public int compareTo(NetworkAgentInfo other) { return other.getCurrentScore() - getCurrentScore(); } }