Merge "Initial IpReachabilityMonitor implementation." into mnc-dev

1 files changed, 354 insertions, 0 deletions

diff --git a/core/java/android/net/IpReachabilityMonitor.java b/core/java/android/net/IpReachabilityMonitor.java
new file mode 100644
index 0000000..7e1c05b
--- /dev/null
+++ b/core/java/android/net/IpReachabilityMonitor.java
@@ -0,0 +1,354 @@
+/*
+ * 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;
+
+import android.net.LinkAddress;
+import android.net.LinkProperties;
+import android.net.ProxyInfo;
+import android.net.RouteInfo;
+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.os.SystemClock;
+import android.system.ErrnoException;
+import android.system.NetlinkSocketAddress;
+import android.system.OsConstants;
+import android.text.TextUtils;
+import android.util.Log;
+
+import java.io.InterruptedIOException;
+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.Set;
+
+
+/**
+ * IpReachabilityMonitor.
+ *
+ * Monitors on-link IP reachability and notifies callers whenever any on-link
+ * addresses of interest appear to have become unresponsive.
+ *
+ * @hide
+ */
+public class IpReachabilityMonitor {
+    private static final String TAG = "IpReachabilityMonitor";
+    private static final boolean DBG = true;
+    private static final boolean VDBG = false;
+
+    public interface Callback {
+        public void notifyLost(InetAddress ip, String logMsg);
+    }
+
+    private final Object mLock = new Object();
+    private final String mInterfaceName;
+    private final int mInterfaceIndex;
+    private final Callback mCallback;
+    private final Set<InetAddress> mIpWatchList;
+    private int mIpWatchListVersion;
+    private boolean mRunning;
+    final private Thread mObserverThread;
+
+    // TODO: consider passing in a NetworkInterface object from the caller.
+    public IpReachabilityMonitor(String ifName, Callback callback) 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);
+        }
+        mCallback = callback;
+        mIpWatchList = new HashSet<InetAddress>();
+        mIpWatchListVersion = 0;
+        mRunning = false;
+        mObserverThread = new Thread(new NetlinkSocketObserver());
+        mObserverThread.start();
+    }
+
+    public void stop() {
+        synchronized (mLock) {
+            mRunning = false;
+            mIpWatchList.clear();
+        }
+    }
+
+    // TODO: add a public dump() method that can be called during a bug report.
+
+    private static Set<InetAddress> getOnLinkNeighbors(LinkProperties lp) {
+        Set<InetAddress> allIps = new HashSet<InetAddress>();
+
+        final List<RouteInfo> routes = lp.getRoutes();
+        for (RouteInfo route : routes) {
+            if (route.hasGateway()) {
+                allIps.add(route.getGateway());
+            }
+        }
+
+        for (InetAddress nameserver : lp.getDnsServers()) {
+            allIps.add(nameserver);
+        }
+
+        try {
+            // Don't block here for DNS lookups.  If the proxy happens to be an
+            // IP literal then we add it the list, but otherwise skip it.
+            allIps.add(NetworkUtils.numericToInetAddress(lp.getHttpProxy().getHost()));
+        } catch (NullPointerException|IllegalArgumentException e) {
+            // No proxy, PAC proxy, or proxy is not a literal IP address.
+        }
+
+        Set<InetAddress> neighbors = new HashSet<InetAddress>();
+        for (InetAddress ip : allIps) {
+            // TODO: consider using the prefixes of the LinkAddresses instead
+            // of the routes--it may be more accurate.
+            for (RouteInfo route : routes) {
+                if (route.hasGateway()) {
+                    continue;  // Not directly connected.
+                }
+                if (route.matches(ip)) {
+                    neighbors.add(ip);
+                    break;
+                }
+            }
+        }
+        return neighbors;
+    }
+
+    private String describeWatchList() {
+        synchronized (mLock) {
+            return "version{" + mIpWatchListVersion + "}, " +
+                    "ips=[" + TextUtils.join(",", mIpWatchList) + "]";
+        }
+    }
+
+    private boolean isWatching(InetAddress ip) {
+        synchronized (mLock) {
+            return mRunning && mIpWatchList.contains(ip);
+        }
+    }
+
+    public void updateLinkProperties(LinkProperties lp) {
+        if (!mInterfaceName.equals(lp.getInterfaceName())) {
+            // TODO: figure out how to cope with interface changes.
+            Log.wtf(TAG, "requested LinkProperties interface '" + lp.getInterfaceName() +
+                    "' does not match: " + mInterfaceName);
+            return;
+        }
+
+        // We rely upon the caller to determine when LinkProperties have actually
+        // changed and call this at the appropriate time.  Note that even though
+        // the LinkProperties may change, the set of on-link neighbors might not.
+        //
+        // Nevertheless, just clear and re-add everything.
+        final Set<InetAddress> neighbors = getOnLinkNeighbors(lp);
+        if (neighbors.isEmpty()) {
+            return;
+        }
+
+        synchronized (mLock) {
+            mIpWatchList.clear();
+            mIpWatchList.addAll(neighbors);
+            mIpWatchListVersion++;
+        }
+        if (DBG) { Log.d(TAG, "watch: " + describeWatchList()); }
+    }
+
+    public void clearLinkProperties() {
+        synchronized (mLock) {
+            mIpWatchList.clear();
+            mIpWatchListVersion++;
+        }
+        if (DBG) { Log.d(TAG, "clear: " + describeWatchList()); }
+    }
+
+    private void notifyLost(InetAddress ip, String msg) {
+        if (!isWatching(ip)) {
+            // Ignore stray notifications.  This can happen when, for example,
+            // several neighbors are reported unreachable or deleted
+            // back-to-back.  Because these messages are parsed serially, and
+            // this method is called for each notification, the caller above us
+            // may have already processed an earlier lost notification and
+            // cleared the watch list as it moves to handle the situation.
+            return;
+        }
+        Log.w(TAG, "ALERT: " + ip.getHostAddress() + " -- " + msg);
+        if (mCallback != null) {
+            mCallback.notifyLost(ip, msg);
+        }
+    }
+
+
+    private final class NetlinkSocketObserver implements Runnable {
+        private static final String TAG = "NetlinkSocketObserver";
+        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) {
+                    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 boolean stillRunning() {
+            synchronized (mLock) {
+                return mRunning;
+            }
+        }
+
+        private void clearNetlinkSocket() {
+            if (mSocket != null) {
+                mSocket.close();
+            }
+            mSocket = null;
+        }
+
+            // 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);
+            }
+
+            if ((msgType == NetlinkConstants.RTM_DELNEIGH) ||
+                (nudState == StructNdMsg.NUD_FAILED)) {
+                final String logMsg = "FAILURE: " + eventMsg;
+                notifyLost(destination, logMsg);
+            }
+        }
+    }
+}