| /* |
| * Copyright (C) 2015 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 android.net.ip; |
| |
| import com.android.internal.annotations.GuardedBy; |
| |
| import android.content.Context; |
| import android.net.LinkAddress; |
| import android.net.LinkProperties; |
| import android.net.LinkProperties.ProvisioningChange; |
| import android.net.ProxyInfo; |
| import android.net.RouteInfo; |
| import android.net.metrics.IpConnectivityLog; |
| import android.net.metrics.IpReachabilityEvent; |
| import android.net.netlink.NetlinkConstants; |
| import android.net.netlink.NetlinkErrorMessage; |
| import android.net.netlink.NetlinkMessage; |
| import android.net.netlink.NetlinkSocket; |
| import android.net.netlink.RtNetlinkNeighborMessage; |
| import android.net.netlink.StructNdaCacheInfo; |
| import android.net.netlink.StructNdMsg; |
| import android.net.netlink.StructNlMsgHdr; |
| import android.net.util.AvoidBadWifiTracker; |
| import android.os.PowerManager; |
| import android.os.SystemClock; |
| import android.system.ErrnoException; |
| import android.system.NetlinkSocketAddress; |
| import android.system.OsConstants; |
| import android.util.Log; |
| |
| import java.io.InterruptedIOException; |
| import java.net.Inet6Address; |
| import java.net.InetAddress; |
| import java.net.InetSocketAddress; |
| import java.net.NetworkInterface; |
| import java.net.SocketAddress; |
| import java.net.SocketException; |
| import java.nio.ByteBuffer; |
| import java.util.Arrays; |
| import java.util.HashMap; |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Set; |
| |
| |
| /** |
| * IpReachabilityMonitor. |
| * |
| * Monitors on-link IP reachability and notifies callers whenever any on-link |
| * addresses of interest appear to have become unresponsive. |
| * |
| * This code does not concern itself with "why" a neighbour might have become |
| * unreachable. Instead, it primarily reacts to the kernel's notion of IP |
| * reachability for each of the neighbours we know to be critically important |
| * to normal network connectivity. As such, it is often "just the messenger": |
| * the neighbours about which it warns are already deemed by the kernel to have |
| * become unreachable. |
| * |
| * |
| * How it works: |
| * |
| * 1. The "on-link neighbours of interest" found in a given LinkProperties |
| * instance are added to a "watch list" via #updateLinkProperties(). |
| * This usually means all default gateways and any on-link DNS servers. |
| * |
| * 2. We listen continuously for netlink neighbour messages (RTM_NEWNEIGH, |
| * RTM_DELNEIGH), watching only for neighbours in the watch list. |
| * |
| * - A neighbour going into NUD_REACHABLE, NUD_STALE, NUD_DELAY, and |
| * even NUD_PROBE is perfectly normal; we merely record the new state. |
| * |
| * - A neighbour's entry may be deleted (RTM_DELNEIGH), for example due |
| * to garbage collection. This is not necessarily of immediate |
| * concern; we record the neighbour as moving to NUD_NONE. |
| * |
| * - A neighbour transitioning to NUD_FAILED (for any reason) is |
| * critically important and is handled as described below in #4. |
| * |
| * 3. All on-link neighbours in the watch list can be forcibly "probed" by |
| * calling #probeAll(). This should be called whenever it is important to |
| * verify that critical neighbours on the link are still reachable, e.g. |
| * when roaming between BSSIDs. |
| * |
| * - The kernel will send unicast ARP requests for IPv4 neighbours and |
| * unicast NS packets for IPv6 neighbours. The expected replies will |
| * likely be unicast. |
| * |
| * - The forced probing is done holding a wakelock. The kernel may, |
| * however, initiate probing of a neighbor on its own, i.e. whenever |
| * a neighbour has expired from NUD_DELAY. |
| * |
| * - The kernel sends: |
| * |
| * /proc/sys/net/ipv{4,6}/neigh/<ifname>/ucast_solicit |
| * |
| * number of probes (usually 3) every: |
| * |
| * /proc/sys/net/ipv{4,6}/neigh/<ifname>/retrans_time_ms |
| * |
| * number of milliseconds (usually 1000ms). This normally results in |
| * 3 unicast packets, 1 per second. |
| * |
| * - If no response is received to any of the probe packets, the kernel |
| * marks the neighbour as being in state NUD_FAILED, and the listening |
| * process in #2 will learn of it. |
| * |
| * 4. We call the supplied Callback#notifyLost() function if the loss of a |
| * neighbour in NUD_FAILED would cause IPv4 or IPv6 configuration to |
| * become incomplete (a loss of provisioning). |
| * |
| * - For example, losing all our IPv4 on-link DNS servers (or losing |
| * our only IPv6 default gateway) constitutes a loss of IPv4 (IPv6) |
| * provisioning; Callback#notifyLost() would be called. |
| * |
| * - Since it can be non-trivial to reacquire certain IP provisioning |
| * state it may be best for the link to disconnect completely and |
| * reconnect afresh. |
| * |
| * @hide |
| */ |
| public class IpReachabilityMonitor { |
| private static final String TAG = "IpReachabilityMonitor"; |
| private static final boolean DBG = false; |
| private static final boolean VDBG = false; |
| |
| public interface Callback { |
| // This callback function must execute as quickly as possible as it is |
| // run on the same thread that listens to kernel neighbor updates. |
| // |
| // TODO: refactor to something like notifyProvisioningLost(String msg). |
| public void notifyLost(InetAddress ip, String logMsg); |
| } |
| |
| private final Object mLock = new Object(); |
| private final PowerManager.WakeLock mWakeLock; |
| private final String mInterfaceName; |
| private final int mInterfaceIndex; |
| private final Callback mCallback; |
| private final AvoidBadWifiTracker mAvoidBadWifiTracker; |
| private final NetlinkSocketObserver mNetlinkSocketObserver; |
| private final Thread mObserverThread; |
| private final IpConnectivityLog mMetricsLog = new IpConnectivityLog(); |
| @GuardedBy("mLock") |
| private LinkProperties mLinkProperties = new LinkProperties(); |
| // TODO: consider a map to a private NeighborState class holding more |
| // information than a single NUD state entry. |
| @GuardedBy("mLock") |
| private Map<InetAddress, Short> mIpWatchList = new HashMap<>(); |
| @GuardedBy("mLock") |
| private int mIpWatchListVersion; |
| @GuardedBy("mLock") |
| private boolean mRunning; |
| // Time in milliseconds of the last forced probe request. |
| private volatile long mLastProbeTimeMs; |
| |
| /** |
| * Make the kernel perform neighbor reachability detection (IPv4 ARP or IPv6 ND) |
| * for the given IP address on the specified interface index. |
| * |
| * @return 0 if the request was successfully passed to the kernel; otherwise return |
| * a non-zero error code. |
| */ |
| private static int probeNeighbor(int ifIndex, InetAddress ip) { |
| final String msgSnippet = "probing ip=" + ip.getHostAddress() + "%" + ifIndex; |
| if (DBG) { Log.d(TAG, msgSnippet); } |
| |
| final byte[] msg = RtNetlinkNeighborMessage.newNewNeighborMessage( |
| 1, ip, StructNdMsg.NUD_PROBE, ifIndex, null); |
| |
| int errno = -OsConstants.EPROTO; |
| try (NetlinkSocket nlSocket = new NetlinkSocket(OsConstants.NETLINK_ROUTE)) { |
| final long IO_TIMEOUT = 300L; |
| nlSocket.connectToKernel(); |
| nlSocket.sendMessage(msg, 0, msg.length, IO_TIMEOUT); |
| final ByteBuffer bytes = nlSocket.recvMessage(IO_TIMEOUT); |
| // recvMessage() guaranteed to not return null if it did not throw. |
| final NetlinkMessage response = NetlinkMessage.parse(bytes); |
| if (response != null && response instanceof NetlinkErrorMessage && |
| (((NetlinkErrorMessage) response).getNlMsgError() != null)) { |
| errno = ((NetlinkErrorMessage) response).getNlMsgError().error; |
| if (errno != 0) { |
| // TODO: consider ignoring EINVAL (-22), which appears to be |
| // normal when probing a neighbor for which the kernel does |
| // not already have / no longer has a link layer address. |
| Log.e(TAG, "Error " + msgSnippet + ", errmsg=" + response.toString()); |
| } |
| } else { |
| String errmsg; |
| if (response == null) { |
| bytes.position(0); |
| errmsg = "raw bytes: " + NetlinkConstants.hexify(bytes); |
| } else { |
| errmsg = response.toString(); |
| } |
| Log.e(TAG, "Error " + msgSnippet + ", errmsg=" + errmsg); |
| } |
| } catch (ErrnoException e) { |
| Log.e(TAG, "Error " + msgSnippet, e); |
| errno = -e.errno; |
| } catch (InterruptedIOException e) { |
| Log.e(TAG, "Error " + msgSnippet, e); |
| errno = -OsConstants.ETIMEDOUT; |
| } catch (SocketException e) { |
| Log.e(TAG, "Error " + msgSnippet, e); |
| errno = -OsConstants.EIO; |
| } |
| return errno; |
| } |
| |
| public IpReachabilityMonitor(Context context, String ifName, Callback callback) { |
| this(context, ifName, callback, null); |
| } |
| |
| public IpReachabilityMonitor(Context context, String ifName, Callback callback, |
| AvoidBadWifiTracker tracker) throws IllegalArgumentException { |
| mInterfaceName = ifName; |
| int ifIndex = -1; |
| try { |
| NetworkInterface netIf = NetworkInterface.getByName(ifName); |
| mInterfaceIndex = netIf.getIndex(); |
| } catch (SocketException | NullPointerException e) { |
| throw new IllegalArgumentException("invalid interface '" + ifName + "': ", e); |
| } |
| mWakeLock = ((PowerManager) context.getSystemService(Context.POWER_SERVICE)).newWakeLock( |
| PowerManager.PARTIAL_WAKE_LOCK, TAG + "." + mInterfaceName); |
| mCallback = callback; |
| mAvoidBadWifiTracker = tracker; |
| mNetlinkSocketObserver = new NetlinkSocketObserver(); |
| mObserverThread = new Thread(mNetlinkSocketObserver); |
| mObserverThread.start(); |
| } |
| |
| public void stop() { |
| synchronized (mLock) { mRunning = false; } |
| clearLinkProperties(); |
| mNetlinkSocketObserver.clearNetlinkSocket(); |
| } |
| |
| // TODO: add a public dump() method that can be called during a bug report. |
| |
| private String describeWatchList() { |
| final String delimiter = ", "; |
| StringBuilder sb = new StringBuilder(); |
| synchronized (mLock) { |
| sb.append("iface{" + mInterfaceName + "/" + mInterfaceIndex + "}, "); |
| sb.append("v{" + mIpWatchListVersion + "}, "); |
| sb.append("ntable=["); |
| boolean firstTime = true; |
| for (Map.Entry<InetAddress, Short> entry : mIpWatchList.entrySet()) { |
| if (firstTime) { |
| firstTime = false; |
| } else { |
| sb.append(delimiter); |
| } |
| sb.append(entry.getKey().getHostAddress() + "/" + |
| StructNdMsg.stringForNudState(entry.getValue())); |
| } |
| sb.append("]"); |
| } |
| return sb.toString(); |
| } |
| |
| private boolean isWatching(InetAddress ip) { |
| synchronized (mLock) { |
| return mRunning && mIpWatchList.containsKey(ip); |
| } |
| } |
| |
| private boolean stillRunning() { |
| synchronized (mLock) { |
| return mRunning; |
| } |
| } |
| |
| private static boolean isOnLink(List<RouteInfo> routes, InetAddress ip) { |
| for (RouteInfo route : routes) { |
| if (!route.hasGateway() && route.matches(ip)) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| private short getNeighborStateLocked(InetAddress ip) { |
| if (mIpWatchList.containsKey(ip)) { |
| return mIpWatchList.get(ip); |
| } |
| return StructNdMsg.NUD_NONE; |
| } |
| |
| public void updateLinkProperties(LinkProperties lp) { |
| if (!mInterfaceName.equals(lp.getInterfaceName())) { |
| // TODO: figure out whether / how to cope with interface changes. |
| Log.wtf(TAG, "requested LinkProperties interface '" + lp.getInterfaceName() + |
| "' does not match: " + mInterfaceName); |
| return; |
| } |
| |
| synchronized (mLock) { |
| mLinkProperties = new LinkProperties(lp); |
| Map<InetAddress, Short> newIpWatchList = new HashMap<>(); |
| |
| final List<RouteInfo> routes = mLinkProperties.getRoutes(); |
| for (RouteInfo route : routes) { |
| if (route.hasGateway()) { |
| InetAddress gw = route.getGateway(); |
| if (isOnLink(routes, gw)) { |
| newIpWatchList.put(gw, getNeighborStateLocked(gw)); |
| } |
| } |
| } |
| |
| for (InetAddress nameserver : lp.getDnsServers()) { |
| if (isOnLink(routes, nameserver)) { |
| newIpWatchList.put(nameserver, getNeighborStateLocked(nameserver)); |
| } |
| } |
| |
| mIpWatchList = newIpWatchList; |
| mIpWatchListVersion++; |
| } |
| if (DBG) { Log.d(TAG, "watch: " + describeWatchList()); } |
| } |
| |
| public void clearLinkProperties() { |
| synchronized (mLock) { |
| mLinkProperties.clear(); |
| mIpWatchList.clear(); |
| mIpWatchListVersion++; |
| } |
| if (DBG) { Log.d(TAG, "clear: " + describeWatchList()); } |
| } |
| |
| private void handleNeighborLost(String msg) { |
| InetAddress ip = null; |
| final ProvisioningChange delta; |
| synchronized (mLock) { |
| LinkProperties whatIfLp = new LinkProperties(mLinkProperties); |
| |
| for (Map.Entry<InetAddress, Short> entry : mIpWatchList.entrySet()) { |
| if (entry.getValue() != StructNdMsg.NUD_FAILED) { |
| continue; |
| } |
| |
| ip = entry.getKey(); |
| for (RouteInfo route : mLinkProperties.getRoutes()) { |
| if (ip.equals(route.getGateway())) { |
| whatIfLp.removeRoute(route); |
| } |
| } |
| |
| if (avoidingBadLinks() || !(ip instanceof Inet6Address)) { |
| // We should do this unconditionally, but alas we cannot: b/31827713. |
| whatIfLp.removeDnsServer(ip); |
| } |
| } |
| |
| delta = LinkProperties.compareProvisioning(mLinkProperties, whatIfLp); |
| } |
| |
| if (delta == ProvisioningChange.LOST_PROVISIONING) { |
| final String logMsg = "FAILURE: LOST_PROVISIONING, " + msg; |
| Log.w(TAG, logMsg); |
| if (mCallback != null) { |
| // TODO: remove |ip| when the callback signature no longer has |
| // an InetAddress argument. |
| mCallback.notifyLost(ip, logMsg); |
| } |
| } |
| logNudFailed(delta); |
| } |
| |
| private boolean avoidingBadLinks() { |
| return (mAvoidBadWifiTracker != null) ? mAvoidBadWifiTracker.currentValue() : true; |
| } |
| |
| public void probeAll() { |
| Set<InetAddress> ipProbeList = new HashSet<InetAddress>(); |
| synchronized (mLock) { |
| ipProbeList.addAll(mIpWatchList.keySet()); |
| } |
| |
| if (!ipProbeList.isEmpty() && stillRunning()) { |
| // Keep the CPU awake long enough to allow all ARP/ND |
| // probes a reasonable chance at success. See b/23197666. |
| // |
| // The wakelock we use is (by default) refcounted, and this version |
| // of acquire(timeout) queues a release message to keep acquisitions |
| // and releases balanced. |
| mWakeLock.acquire(getProbeWakeLockDuration()); |
| } |
| |
| for (InetAddress target : ipProbeList) { |
| if (!stillRunning()) { |
| break; |
| } |
| final int returnValue = probeNeighbor(mInterfaceIndex, target); |
| logEvent(IpReachabilityEvent.PROBE, returnValue); |
| } |
| mLastProbeTimeMs = SystemClock.elapsedRealtime(); |
| } |
| |
| private static long getProbeWakeLockDuration() { |
| // Ideally, this would be computed by examining the values of: |
| // |
| // /proc/sys/net/ipv[46]/neigh/<ifname>/ucast_solicit |
| // |
| // and: |
| // |
| // /proc/sys/net/ipv[46]/neigh/<ifname>/retrans_time_ms |
| // |
| // For now, just make some assumptions. |
| final long numUnicastProbes = 3; |
| final long retransTimeMs = 1000; |
| final long gracePeriodMs = 500; |
| return (numUnicastProbes * retransTimeMs) + gracePeriodMs; |
| } |
| |
| private void logEvent(int probeType, int errorCode) { |
| int eventType = probeType | (errorCode & 0xff); |
| mMetricsLog.log(new IpReachabilityEvent(mInterfaceName, eventType)); |
| } |
| |
| private void logNudFailed(ProvisioningChange delta) { |
| long duration = SystemClock.elapsedRealtime() - mLastProbeTimeMs; |
| boolean isFromProbe = (duration < getProbeWakeLockDuration()); |
| boolean isProvisioningLost = (delta == ProvisioningChange.LOST_PROVISIONING); |
| int eventType = IpReachabilityEvent.nudFailureEventType(isFromProbe, isProvisioningLost); |
| mMetricsLog.log(new IpReachabilityEvent(mInterfaceName, eventType)); |
| } |
| |
| // TODO: simplify the number of objects by making this extend Thread. |
| private final class NetlinkSocketObserver implements Runnable { |
| private NetlinkSocket mSocket; |
| |
| @Override |
| public void run() { |
| if (VDBG) { Log.d(TAG, "Starting observing thread."); } |
| synchronized (mLock) { mRunning = true; } |
| |
| try { |
| setupNetlinkSocket(); |
| } catch (ErrnoException | SocketException e) { |
| Log.e(TAG, "Failed to suitably initialize a netlink socket", e); |
| synchronized (mLock) { mRunning = false; } |
| } |
| |
| ByteBuffer byteBuffer; |
| while (stillRunning()) { |
| try { |
| byteBuffer = recvKernelReply(); |
| } catch (ErrnoException e) { |
| if (stillRunning()) { Log.w(TAG, "ErrnoException: ", e); } |
| break; |
| } |
| final long whenMs = SystemClock.elapsedRealtime(); |
| if (byteBuffer == null) { |
| continue; |
| } |
| parseNetlinkMessageBuffer(byteBuffer, whenMs); |
| } |
| |
| clearNetlinkSocket(); |
| |
| synchronized (mLock) { mRunning = false; } |
| if (VDBG) { Log.d(TAG, "Finishing observing thread."); } |
| } |
| |
| private void clearNetlinkSocket() { |
| if (mSocket != null) { |
| mSocket.close(); |
| } |
| } |
| |
| // TODO: Refactor the main loop to recreate the socket upon recoverable errors. |
| private void setupNetlinkSocket() throws ErrnoException, SocketException { |
| clearNetlinkSocket(); |
| mSocket = new NetlinkSocket(OsConstants.NETLINK_ROUTE); |
| |
| final NetlinkSocketAddress listenAddr = new NetlinkSocketAddress( |
| 0, OsConstants.RTMGRP_NEIGH); |
| mSocket.bind(listenAddr); |
| |
| if (VDBG) { |
| final NetlinkSocketAddress nlAddr = mSocket.getLocalAddress(); |
| Log.d(TAG, "bound to sockaddr_nl{" |
| + ((long) (nlAddr.getPortId() & 0xffffffff)) + ", " |
| + nlAddr.getGroupsMask() |
| + "}"); |
| } |
| } |
| |
| private ByteBuffer recvKernelReply() throws ErrnoException { |
| try { |
| return mSocket.recvMessage(0); |
| } catch (InterruptedIOException e) { |
| // Interruption or other error, e.g. another thread closed our file descriptor. |
| } catch (ErrnoException e) { |
| if (e.errno != OsConstants.EAGAIN) { |
| throw e; |
| } |
| } |
| return null; |
| } |
| |
| private void parseNetlinkMessageBuffer(ByteBuffer byteBuffer, long whenMs) { |
| while (byteBuffer.remaining() > 0) { |
| final int position = byteBuffer.position(); |
| final NetlinkMessage nlMsg = NetlinkMessage.parse(byteBuffer); |
| if (nlMsg == null || nlMsg.getHeader() == null) { |
| byteBuffer.position(position); |
| Log.e(TAG, "unparsable netlink msg: " + NetlinkConstants.hexify(byteBuffer)); |
| break; |
| } |
| |
| final int srcPortId = nlMsg.getHeader().nlmsg_pid; |
| if (srcPortId != 0) { |
| Log.e(TAG, "non-kernel source portId: " + ((long) (srcPortId & 0xffffffff))); |
| break; |
| } |
| |
| if (nlMsg instanceof NetlinkErrorMessage) { |
| Log.e(TAG, "netlink error: " + nlMsg); |
| continue; |
| } else if (!(nlMsg instanceof RtNetlinkNeighborMessage)) { |
| if (DBG) { |
| Log.d(TAG, "non-rtnetlink neighbor msg: " + nlMsg); |
| } |
| continue; |
| } |
| |
| evaluateRtNetlinkNeighborMessage((RtNetlinkNeighborMessage) nlMsg, whenMs); |
| } |
| } |
| |
| private void evaluateRtNetlinkNeighborMessage( |
| RtNetlinkNeighborMessage neighMsg, long whenMs) { |
| final StructNdMsg ndMsg = neighMsg.getNdHeader(); |
| if (ndMsg == null || ndMsg.ndm_ifindex != mInterfaceIndex) { |
| return; |
| } |
| |
| final InetAddress destination = neighMsg.getDestination(); |
| if (!isWatching(destination)) { |
| return; |
| } |
| |
| final short msgType = neighMsg.getHeader().nlmsg_type; |
| final short nudState = ndMsg.ndm_state; |
| final String eventMsg = "NeighborEvent{" |
| + "elapsedMs=" + whenMs + ", " |
| + destination.getHostAddress() + ", " |
| + "[" + NetlinkConstants.hexify(neighMsg.getLinkLayerAddress()) + "], " |
| + NetlinkConstants.stringForNlMsgType(msgType) + ", " |
| + StructNdMsg.stringForNudState(nudState) |
| + "}"; |
| |
| if (VDBG) { |
| Log.d(TAG, neighMsg.toString()); |
| } else if (DBG) { |
| Log.d(TAG, eventMsg); |
| } |
| |
| synchronized (mLock) { |
| if (mIpWatchList.containsKey(destination)) { |
| final short value = |
| (msgType == NetlinkConstants.RTM_DELNEIGH) |
| ? StructNdMsg.NUD_NONE |
| : nudState; |
| mIpWatchList.put(destination, value); |
| } |
| } |
| |
| if (nudState == StructNdMsg.NUD_FAILED) { |
| Log.w(TAG, "ALERT: " + eventMsg); |
| handleNeighborLost(eventMsg); |
| } |
| } |
| } |
| } |