Remove IpClient usage of NetworkManagementService

Use the new NetworkObserverRegistry instead.

Test: atest FrameworksNetTests NetworkStackTests
Test: flashed, WiFi working fine
Bug: 112869080
Change-Id: If16ecfd6489f86afec67c22b4c3692cd68f4edbf

1 files changed, 378 insertions, 0 deletions

diff --git a/src/android/net/ip/IpClientLinkObserver.java b/src/android/net/ip/IpClientLinkObserver.java
new file mode 100644
index 0000000..8ad99aa
--- /dev/null
+++ b/src/android/net/ip/IpClientLinkObserver.java
@@ -0,0 +1,378 @@
+/*
+ * 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 android.net.ip;
+
+import android.net.InetAddresses;
+import android.net.LinkAddress;
+import android.net.LinkProperties;
+import android.net.RouteInfo;
+import android.util.Log;
+
+import com.android.server.NetworkObserver;
+
+import java.net.InetAddress;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Keeps track of link configuration received from Netd.
+ *
+ * An instance of this class is constructed by passing in an interface name and a callback. The
+ * owner is then responsible for registering the tracker with NetworkObserverRegistry. When the
+ * class receives update notifications, it applies the update to its local LinkProperties, and if
+ * something has changed, notifies its owner of the update via the callback.
+ *
+ * The owner can then call {@code getLinkProperties()} in order to find out
+ * what changed. If in the meantime the LinkProperties stored here have changed,
+ * this class will return the current LinkProperties. Because each change
+ * triggers an update callback after the change is made, the owner may get more
+ * callbacks than strictly necessary (some of which may be no-ops), but will not
+ * be out of sync once all callbacks have been processed.
+ *
+ * Threading model:
+ *
+ * - The owner of this class is expected to create it, register it, and call
+ *   getLinkProperties or clearLinkProperties on its thread.
+ * - Most of the methods in the class are implementing NetworkObserver and are called
+ *   on the handler used to register the observer.
+ * - All accesses to mLinkProperties must be synchronized(this). All the other
+ *   member variables are immutable once the object is constructed.
+ *
+ * @hide
+ */
+public class IpClientLinkObserver implements NetworkObserver {
+    private final String mTag;
+
+    /**
+     * Callback used by {@link IpClientLinkObserver} to send update notifications.
+     */
+    public interface Callback {
+        /**
+         * Called when some properties of the link were updated.
+         */
+        void update();
+    }
+
+    private final String mInterfaceName;
+    private final Callback mCallback;
+    private final LinkProperties mLinkProperties;
+    private DnsServerRepository mDnsServerRepository;
+
+    private static final boolean DBG = false;
+
+    public IpClientLinkObserver(String iface, Callback callback) {
+        mTag = "NetlinkTracker/" + iface;
+        mInterfaceName = iface;
+        mCallback = callback;
+        mLinkProperties = new LinkProperties();
+        mLinkProperties.setInterfaceName(mInterfaceName);
+        mDnsServerRepository = new DnsServerRepository();
+    }
+
+    private void maybeLog(String operation, String iface, LinkAddress address) {
+        if (DBG) {
+            Log.d(mTag, operation + ": " + address + " on " + iface
+                    + " flags " + address.getFlags() + " scope " + address.getScope());
+        }
+    }
+
+    private void maybeLog(String operation, Object o) {
+        if (DBG) {
+            Log.d(mTag, operation + ": " + o.toString());
+        }
+    }
+
+    @Override
+    public void onInterfaceRemoved(String iface) {
+        maybeLog("interfaceRemoved", iface);
+        if (mInterfaceName.equals(iface)) {
+            // Our interface was removed. Clear our LinkProperties and tell our owner that they are
+            // now empty. Note that from the moment that the interface is removed, any further
+            // interface-specific messages (e.g., RTM_DELADDR) will not reach us, because the netd
+            // code that parses them will not be able to resolve the ifindex to an interface name.
+            clearLinkProperties();
+            mCallback.update();
+        }
+    }
+
+    @Override
+    public void onInterfaceAddressUpdated(LinkAddress address, String iface) {
+        if (mInterfaceName.equals(iface)) {
+            maybeLog("addressUpdated", iface, address);
+            boolean changed;
+            synchronized (this) {
+                changed = mLinkProperties.addLinkAddress(address);
+            }
+            if (changed) {
+                mCallback.update();
+            }
+        }
+    }
+
+    @Override
+    public void onInterfaceAddressRemoved(LinkAddress address, String iface) {
+        if (mInterfaceName.equals(iface)) {
+            maybeLog("addressRemoved", iface, address);
+            boolean changed;
+            synchronized (this) {
+                changed = mLinkProperties.removeLinkAddress(address);
+            }
+            if (changed) {
+                mCallback.update();
+            }
+        }
+    }
+
+    @Override
+    public void onRouteUpdated(RouteInfo route) {
+        if (mInterfaceName.equals(route.getInterface())) {
+            maybeLog("routeUpdated", route);
+            boolean changed;
+            synchronized (this) {
+                changed = mLinkProperties.addRoute(route);
+            }
+            if (changed) {
+                mCallback.update();
+            }
+        }
+    }
+
+    @Override
+    public void onRouteRemoved(RouteInfo route) {
+        if (mInterfaceName.equals(route.getInterface())) {
+            maybeLog("routeRemoved", route);
+            boolean changed;
+            synchronized (this) {
+                changed = mLinkProperties.removeRoute(route);
+            }
+            if (changed) {
+                mCallback.update();
+            }
+        }
+    }
+
+    @Override
+    public void onInterfaceDnsServerInfo(String iface, long lifetime, String[] addresses) {
+        if (mInterfaceName.equals(iface)) {
+            maybeLog("interfaceDnsServerInfo", Arrays.toString(addresses));
+            boolean changed = mDnsServerRepository.addServers(lifetime, addresses);
+            if (changed) {
+                synchronized (this) {
+                    mDnsServerRepository.setDnsServersOn(mLinkProperties);
+                }
+                mCallback.update();
+            }
+        }
+    }
+
+    /**
+     * Returns a copy of this object's LinkProperties.
+     */
+    public synchronized LinkProperties getLinkProperties() {
+        return new LinkProperties(mLinkProperties);
+    }
+
+    /**
+     * Reset this object's LinkProperties.
+     */
+    public synchronized void clearLinkProperties() {
+        // Clear the repository before clearing mLinkProperties. That way, if a clear() happens
+        // while interfaceDnsServerInfo() is being called, we'll end up with no DNS servers in
+        // mLinkProperties, as desired.
+        mDnsServerRepository = new DnsServerRepository();
+        mLinkProperties.clear();
+        mLinkProperties.setInterfaceName(mInterfaceName);
+    }
+
+    /**
+     * Tracks DNS server updates received from Netlink.
+     *
+     * The network may announce an arbitrary number of DNS servers in Router Advertisements at any
+     * time. Each announcement has a lifetime; when the lifetime expires, the servers should not be
+     * used any more. In this way, the network can gracefully migrate clients from one set of DNS
+     * servers to another. Announcements can both raise and lower the lifetime, and an announcement
+     * can expire servers by announcing them with a lifetime of zero.
+     *
+     * Typically the system will only use a small number (2 or 3; {@code NUM_CURRENT_SERVERS}) of
+     * DNS servers at any given time. These are referred to as the current servers. In case all the
+     * current servers expire, the class also keeps track of a larger (but limited) number of
+     * servers that are promoted to current servers when the current ones expire. In order to
+     * minimize updates to the rest of the system (and potentially expensive cache flushes) this
+     * class attempts to keep the list of current servers constant where possible. More
+     * specifically, the list of current servers is only updated if a new server is learned and
+     * there are not yet {@code NUM_CURRENT_SERVERS} current servers, or if one or more of the
+     * current servers expires or is pushed out of the set. Therefore, the current servers will not
+     * necessarily be the ones with the highest lifetime, but the ones learned first.
+     *
+     * This is by design: if instead the class always preferred the servers with the highest
+     * lifetime, a (misconfigured?) network where two or more routers announce more than
+     * {@code NUM_CURRENT_SERVERS} unique servers would cause persistent oscillations.
+     *
+     * TODO: Currently servers are only expired when a new DNS update is received.
+     * Update them using timers, or possibly on every notification received by NetlinkTracker.
+     *
+     * Threading model: run by NetlinkTracker. Methods are synchronized(this) just in case netlink
+     * notifications are sent by multiple threads. If future threads use alarms to expire, those
+     * alarms must also be synchronized(this).
+     *
+     */
+    private static class DnsServerRepository {
+
+        /** How many DNS servers we will use. 3 is suggested by RFC 6106. */
+        static final int NUM_CURRENT_SERVERS = 3;
+
+        /** How many DNS servers we'll keep track of, in total. */
+        static final int NUM_SERVERS = 12;
+
+        /** Stores up to {@code NUM_CURRENT_SERVERS} DNS servers we're currently using. */
+        private Set<InetAddress> mCurrentServers;
+
+        public static final String TAG = "DnsServerRepository";
+
+        /**
+         * Stores all the DNS servers we know about, for use when the current servers expire.
+         * Always sorted in order of decreasing expiry. The elements in this list are also the
+         * values of mIndex, and may be elements in mCurrentServers.
+         */
+        private ArrayList<DnsServerEntry> mAllServers;
+
+        /**
+         * Indexes the servers so we can update their lifetimes more quickly in the common case
+         * where servers are not being added, but only being refreshed.
+         */
+        private HashMap<InetAddress, DnsServerEntry> mIndex;
+
+        DnsServerRepository() {
+            mCurrentServers = new HashSet<>();
+            mAllServers = new ArrayList<>(NUM_SERVERS);
+            mIndex = new HashMap<>(NUM_SERVERS);
+        }
+
+        /** Sets the DNS servers of the provided LinkProperties object to the current servers. */
+        public synchronized void setDnsServersOn(LinkProperties lp) {
+            lp.setDnsServers(mCurrentServers);
+        }
+
+        /**
+         * Notifies the class of new DNS server information.
+         * @param lifetime the time in seconds that the DNS servers are valid.
+         * @param addresses the string representations of the IP addresses of DNS servers to use.
+         */
+        public synchronized boolean addServers(long lifetime, String[] addresses) {
+            // The lifetime is actually an unsigned 32-bit number, but Java doesn't have unsigned.
+            // Technically 0xffffffff (the maximum) is special and means "forever", but 2^32 seconds
+            // (136 years) is close enough.
+            long now = System.currentTimeMillis();
+            long expiry = now + 1000 * lifetime;
+
+            // Go through the list of servers. For each one, update the entry if one exists, and
+            // create one if it doesn't.
+            for (String addressString : addresses) {
+                InetAddress address;
+                try {
+                    address = InetAddresses.parseNumericAddress(addressString);
+                } catch (IllegalArgumentException ex) {
+                    continue;
+                }
+
+                if (!updateExistingEntry(address, expiry)) {
+                    // There was no entry for this server. Create one, unless it's already expired
+                    // (i.e., if the lifetime is zero; it cannot be < 0 because it's unsigned).
+                    if (expiry > now) {
+                        DnsServerEntry entry = new DnsServerEntry(address, expiry);
+                        mAllServers.add(entry);
+                        mIndex.put(address, entry);
+                    }
+                }
+            }
+
+            // Sort the servers by expiry.
+            Collections.sort(mAllServers);
+
+            // Prune excess entries and update the current server list.
+            return updateCurrentServers();
+        }
+
+        private synchronized boolean updateExistingEntry(InetAddress address, long expiry) {
+            DnsServerEntry existing = mIndex.get(address);
+            if (existing != null) {
+                existing.expiry = expiry;
+                return true;
+            }
+            return false;
+        }
+
+        private synchronized boolean updateCurrentServers() {
+            long now = System.currentTimeMillis();
+            boolean changed = false;
+
+            // Prune excess or expired entries.
+            for (int i = mAllServers.size() - 1; i >= 0; i--) {
+                if (i >= NUM_SERVERS || mAllServers.get(i).expiry < now) {
+                    DnsServerEntry removed = mAllServers.remove(i);
+                    mIndex.remove(removed.address);
+                    changed |= mCurrentServers.remove(removed.address);
+                } else {
+                    break;
+                }
+            }
+
+            // Add servers to the current set, in order of decreasing lifetime, until it has enough.
+            // Prefer existing servers over new servers in order to minimize updates to the rest of
+            // the system and avoid persistent oscillations.
+            for (DnsServerEntry entry : mAllServers) {
+                if (mCurrentServers.size() < NUM_CURRENT_SERVERS) {
+                    changed |= mCurrentServers.add(entry.address);
+                } else {
+                    break;
+                }
+            }
+            return changed;
+        }
+    }
+
+    /**
+     * Represents a DNS server entry with an expiry time.
+     *
+     * Implements Comparable so DNS server entries can be sorted by lifetime, longest-lived first.
+     * The ordering of entries with the same lifetime is unspecified, because given two servers with
+     * identical lifetimes, we don't care which one we use, and only comparing the lifetime is much
+     * faster than comparing the IP address as well.
+     *
+     * Note: this class has a natural ordering that is inconsistent with equals.
+     */
+    private static class DnsServerEntry implements Comparable<DnsServerEntry> {
+        /** The IP address of the DNS server. */
+        public final InetAddress address;
+        /** The time until which the DNS server may be used. A Java millisecond time as might be
+         * returned by currentTimeMillis(). */
+        public long expiry;
+
+        DnsServerEntry(InetAddress address, long expiry) throws IllegalArgumentException {
+            this.address = address;
+            this.expiry = expiry;
+        }
+
+        public int compareTo(DnsServerEntry other) {
+            return Long.compare(other.expiry, this.expiry);
+        }
+    }
+}