Merge SP1A.201105.002

Change-Id: Iec83a0c1f6f286a1e51abfc4356633ca9d8aea5f

1 files changed, 0 insertions, 744 deletions

diff --git a/packages/Tethering/src/android/net/ip/RouterAdvertisementDaemon.java b/packages/Tethering/src/android/net/ip/RouterAdvertisementDaemon.java
deleted file mode 100644
index 7c0b7cc7515c..000000000000
--- a/packages/Tethering/src/android/net/ip/RouterAdvertisementDaemon.java
+++ /dev/null
@@ -1,744 +0,0 @@
-/*
- * Copyright (C) 2016 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 static android.net.util.NetworkConstants.IPV6_MIN_MTU;
-import static android.net.util.NetworkConstants.RFC7421_PREFIX_LENGTH;
-import static android.net.util.TetheringUtils.getAllNodesForScopeId;
-import static android.system.OsConstants.AF_INET6;
-import static android.system.OsConstants.IPPROTO_ICMPV6;
-import static android.system.OsConstants.SOCK_RAW;
-import static android.system.OsConstants.SOL_SOCKET;
-import static android.system.OsConstants.SO_SNDTIMEO;
-
-import android.net.IpPrefix;
-import android.net.LinkAddress;
-import android.net.TrafficStats;
-import android.net.util.InterfaceParams;
-import android.net.util.SocketUtils;
-import android.net.util.TetheringUtils;
-import android.system.ErrnoException;
-import android.system.Os;
-import android.system.StructTimeval;
-import android.util.Log;
-
-import com.android.internal.annotations.GuardedBy;
-import com.android.internal.util.TrafficStatsConstants;
-
-import java.io.FileDescriptor;
-import java.io.IOException;
-import java.net.Inet6Address;
-import java.net.InetAddress;
-import java.net.InetSocketAddress;
-import java.net.SocketException;
-import java.nio.BufferOverflowException;
-import java.nio.ByteBuffer;
-import java.nio.ByteOrder;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.Iterator;
-import java.util.Map;
-import java.util.Random;
-import java.util.Set;
-import java.util.concurrent.atomic.AtomicInteger;
-
-
-/**
- * Basic IPv6 Router Advertisement Daemon.
- *
- * TODO:
- *
- *     - Rewrite using Handler (and friends) so that AlarmManager can deliver
- *       "kick" messages when it's time to send a multicast RA.
- *
- * @hide
- */
-public class RouterAdvertisementDaemon {
-    private static final String TAG = RouterAdvertisementDaemon.class.getSimpleName();
-    private static final byte ICMPV6_ND_ROUTER_SOLICIT = asByte(133);
-    private static final byte ICMPV6_ND_ROUTER_ADVERT  = asByte(134);
-    private static final int MIN_RA_HEADER_SIZE = 16;
-
-    // Summary of various timers and lifetimes.
-    private static final int MIN_RTR_ADV_INTERVAL_SEC = 300;
-    private static final int MAX_RTR_ADV_INTERVAL_SEC = 600;
-    // In general, router, prefix, and DNS lifetimes are all advised to be
-    // greater than or equal to 3 * MAX_RTR_ADV_INTERVAL.  Here, we double
-    // that to allow for multicast packet loss.
-    //
-    // This MAX_RTR_ADV_INTERVAL_SEC and DEFAULT_LIFETIME are also consistent
-    // with the https://tools.ietf.org/html/rfc7772#section-4 discussion of
-    // "approximately 7 RAs per hour".
-    private static final int DEFAULT_LIFETIME = 6 * MAX_RTR_ADV_INTERVAL_SEC;
-    // From https://tools.ietf.org/html/rfc4861#section-10 .
-    private static final int MIN_DELAY_BETWEEN_RAS_SEC = 3;
-    // Both initial and final RAs, but also for changes in RA contents.
-    // From https://tools.ietf.org/html/rfc4861#section-10 .
-    private static final int  MAX_URGENT_RTR_ADVERTISEMENTS = 5;
-
-    private static final int DAY_IN_SECONDS = 86_400;
-
-    private final InterfaceParams mInterface;
-    private final InetSocketAddress mAllNodes;
-
-    // This lock is to protect the RA from being updated while being
-    // transmitted on another thread  (multicast or unicast).
-    //
-    // TODO: This should be handled with a more RCU-like approach.
-    private final Object mLock = new Object();
-    @GuardedBy("mLock")
-    private final byte[] mRA = new byte[IPV6_MIN_MTU];
-    @GuardedBy("mLock")
-    private int mRaLength;
-    @GuardedBy("mLock")
-    private final DeprecatedInfoTracker mDeprecatedInfoTracker;
-    @GuardedBy("mLock")
-    private RaParams mRaParams;
-
-    private volatile FileDescriptor mSocket;
-    private volatile MulticastTransmitter mMulticastTransmitter;
-    private volatile UnicastResponder mUnicastResponder;
-
-    /** Encapsulate the RA parameters for RouterAdvertisementDaemon.*/
-    public static class RaParams {
-        // Tethered traffic will have the hop limit properly decremented.
-        // Consequently, set the hoplimit greater by one than the upstream
-        // unicast hop limit.
-        //
-        // TODO: Dynamically pass down the IPV6_UNICAST_HOPS value from the
-        // upstream interface for more correct behaviour.
-        static final byte DEFAULT_HOPLIMIT = 65;
-
-        public boolean hasDefaultRoute;
-        public byte hopLimit;
-        public int mtu;
-        public HashSet<IpPrefix> prefixes;
-        public HashSet<Inet6Address> dnses;
-
-        public RaParams() {
-            hasDefaultRoute = false;
-            hopLimit = DEFAULT_HOPLIMIT;
-            mtu = IPV6_MIN_MTU;
-            prefixes = new HashSet<IpPrefix>();
-            dnses = new HashSet<Inet6Address>();
-        }
-
-        public RaParams(RaParams other) {
-            hasDefaultRoute = other.hasDefaultRoute;
-            hopLimit = other.hopLimit;
-            mtu = other.mtu;
-            prefixes = (HashSet) other.prefixes.clone();
-            dnses = (HashSet) other.dnses.clone();
-        }
-
-        /**
-         * Returns the subset of RA parameters that become deprecated when
-         * moving from announcing oldRa to announcing newRa.
-         *
-         * Currently only tracks differences in |prefixes| and |dnses|.
-         */
-        public static RaParams getDeprecatedRaParams(RaParams oldRa, RaParams newRa) {
-            RaParams newlyDeprecated = new RaParams();
-
-            if (oldRa != null) {
-                for (IpPrefix ipp : oldRa.prefixes) {
-                    if (newRa == null || !newRa.prefixes.contains(ipp)) {
-                        newlyDeprecated.prefixes.add(ipp);
-                    }
-                }
-
-                for (Inet6Address dns : oldRa.dnses) {
-                    if (newRa == null || !newRa.dnses.contains(dns)) {
-                        newlyDeprecated.dnses.add(dns);
-                    }
-                }
-            }
-
-            return newlyDeprecated;
-        }
-    }
-
-    private static class DeprecatedInfoTracker {
-        private final HashMap<IpPrefix, Integer> mPrefixes = new HashMap<>();
-        private final HashMap<Inet6Address, Integer> mDnses = new HashMap<>();
-
-        Set<IpPrefix> getPrefixes() {
-            return mPrefixes.keySet();
-        }
-
-        void putPrefixes(Set<IpPrefix> prefixes) {
-            for (IpPrefix ipp : prefixes) {
-                mPrefixes.put(ipp, MAX_URGENT_RTR_ADVERTISEMENTS);
-            }
-        }
-
-        void removePrefixes(Set<IpPrefix> prefixes) {
-            for (IpPrefix ipp : prefixes) {
-                mPrefixes.remove(ipp);
-            }
-        }
-
-        Set<Inet6Address> getDnses() {
-            return mDnses.keySet();
-        }
-
-        void putDnses(Set<Inet6Address> dnses) {
-            for (Inet6Address dns : dnses) {
-                mDnses.put(dns, MAX_URGENT_RTR_ADVERTISEMENTS);
-            }
-        }
-
-        void removeDnses(Set<Inet6Address> dnses) {
-            for (Inet6Address dns : dnses) {
-                mDnses.remove(dns);
-            }
-        }
-
-        boolean isEmpty() {
-            return mPrefixes.isEmpty() && mDnses.isEmpty();
-        }
-
-        private boolean decrementCounters() {
-            boolean removed = decrementCounter(mPrefixes);
-            removed |= decrementCounter(mDnses);
-            return removed;
-        }
-
-        private <T> boolean decrementCounter(HashMap<T, Integer> map) {
-            boolean removed = false;
-
-            for (Iterator<Map.Entry<T, Integer>> it = map.entrySet().iterator();
-                    it.hasNext();) {
-                Map.Entry<T, Integer> kv = it.next();
-                if (kv.getValue() == 0) {
-                    it.remove();
-                    removed = true;
-                } else {
-                    kv.setValue(kv.getValue() - 1);
-                }
-            }
-
-            return removed;
-        }
-    }
-
-    public RouterAdvertisementDaemon(InterfaceParams ifParams) {
-        mInterface = ifParams;
-        mAllNodes = new InetSocketAddress(getAllNodesForScopeId(mInterface.index), 0);
-        mDeprecatedInfoTracker = new DeprecatedInfoTracker();
-    }
-
-    /** Build new RA.*/
-    public void buildNewRa(RaParams deprecatedParams, RaParams newParams) {
-        synchronized (mLock) {
-            if (deprecatedParams != null) {
-                mDeprecatedInfoTracker.putPrefixes(deprecatedParams.prefixes);
-                mDeprecatedInfoTracker.putDnses(deprecatedParams.dnses);
-            }
-
-            if (newParams != null) {
-                // Process information that is no longer deprecated.
-                mDeprecatedInfoTracker.removePrefixes(newParams.prefixes);
-                mDeprecatedInfoTracker.removeDnses(newParams.dnses);
-            }
-
-            mRaParams = newParams;
-            assembleRaLocked();
-        }
-
-        maybeNotifyMulticastTransmitter();
-    }
-
-    /** Start router advertisement daemon. */
-    public boolean start() {
-        if (!createSocket()) {
-            return false;
-        }
-
-        mMulticastTransmitter = new MulticastTransmitter();
-        mMulticastTransmitter.start();
-
-        mUnicastResponder = new UnicastResponder();
-        mUnicastResponder.start();
-
-        return true;
-    }
-
-    /** Stop router advertisement daemon. */
-    public void stop() {
-        closeSocket();
-        // Wake up mMulticastTransmitter thread to interrupt a potential 1 day sleep before
-        // the thread's termination.
-        maybeNotifyMulticastTransmitter();
-        mMulticastTransmitter = null;
-        mUnicastResponder = null;
-    }
-
-    @GuardedBy("mLock")
-    private void assembleRaLocked() {
-        final ByteBuffer ra = ByteBuffer.wrap(mRA);
-        ra.order(ByteOrder.BIG_ENDIAN);
-
-        final boolean haveRaParams = (mRaParams != null);
-        boolean shouldSendRA = false;
-
-        try {
-            putHeader(ra, haveRaParams && mRaParams.hasDefaultRoute,
-                    haveRaParams ? mRaParams.hopLimit : RaParams.DEFAULT_HOPLIMIT);
-            putSlla(ra, mInterface.macAddr.toByteArray());
-            mRaLength = ra.position();
-
-            // https://tools.ietf.org/html/rfc5175#section-4 says:
-            //
-            //     "MUST NOT be added to a Router Advertisement message
-            //      if no flags in the option are set."
-            //
-            // putExpandedFlagsOption(ra);
-
-            if (haveRaParams) {
-                putMtu(ra, mRaParams.mtu);
-                mRaLength = ra.position();
-
-                for (IpPrefix ipp : mRaParams.prefixes) {
-                    putPio(ra, ipp, DEFAULT_LIFETIME, DEFAULT_LIFETIME);
-                    mRaLength = ra.position();
-                    shouldSendRA = true;
-                }
-
-                if (mRaParams.dnses.size() > 0) {
-                    putRdnss(ra, mRaParams.dnses, DEFAULT_LIFETIME);
-                    mRaLength = ra.position();
-                    shouldSendRA = true;
-                }
-            }
-
-            for (IpPrefix ipp : mDeprecatedInfoTracker.getPrefixes()) {
-                putPio(ra, ipp, 0, 0);
-                mRaLength = ra.position();
-                shouldSendRA = true;
-            }
-
-            final Set<Inet6Address> deprecatedDnses = mDeprecatedInfoTracker.getDnses();
-            if (!deprecatedDnses.isEmpty()) {
-                putRdnss(ra, deprecatedDnses, 0);
-                mRaLength = ra.position();
-                shouldSendRA = true;
-            }
-        } catch (BufferOverflowException e) {
-            // The packet up to mRaLength  is valid, since it has been updated
-            // progressively as the RA was built. Log an error, and continue
-            // on as best as possible.
-            Log.e(TAG, "Could not construct new RA: " + e);
-        }
-
-        // We have nothing worth announcing; indicate as much to maybeSendRA().
-        if (!shouldSendRA) {
-            mRaLength = 0;
-        }
-    }
-
-    private void maybeNotifyMulticastTransmitter() {
-        final MulticastTransmitter m = mMulticastTransmitter;
-        if (m != null) {
-            m.hup();
-        }
-    }
-
-    private static byte asByte(int value) {
-        return (byte) value;
-    }
-    private static short asShort(int value) {
-        return (short) value;
-    }
-
-    private static void putHeader(ByteBuffer ra, boolean hasDefaultRoute, byte hopLimit) {
-        /**
-            Router Advertisement Message Format
-
-             0                   1                   2                   3
-             0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |     Type      |     Code      |          Checksum             |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            | Cur Hop Limit |M|O|H|Prf|P|R|R|       Router Lifetime         |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |                         Reachable Time                        |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |                          Retrans Timer                        |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |   Options ...
-            +-+-+-+-+-+-+-+-+-+-+-+-
-        */
-        ra.put(ICMPV6_ND_ROUTER_ADVERT)
-                .put(asByte(0))
-                .putShort(asShort(0))
-                .put(hopLimit)
-                // RFC 4191 "high" preference, iff. advertising a default route.
-                .put(hasDefaultRoute ? asByte(0x08) : asByte(0))
-                .putShort(hasDefaultRoute ? asShort(DEFAULT_LIFETIME) : asShort(0))
-                .putInt(0)
-                .putInt(0);
-    }
-
-    private static void putSlla(ByteBuffer ra, byte[] slla) {
-        /**
-            Source/Target Link-layer Address
-
-             0                   1                   2                   3
-             0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |     Type      |    Length     |    Link-Layer Address ...
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-        */
-        if (slla == null || slla.length != 6) {
-            // Only IEEE 802.3 6-byte addresses are supported.
-            return;
-        }
-
-        final byte nd_option_slla = 1;
-        final byte slla_num_8octets = 1;
-        ra.put(nd_option_slla)
-            .put(slla_num_8octets)
-            .put(slla);
-    }
-
-    private static void putExpandedFlagsOption(ByteBuffer ra) {
-        /**
-            Router Advertisement Expanded Flags Option
-
-             0                   1                   2                   3
-             0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |     Type      |    Length     |         Bit fields available ..
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            ... for assignment                                              |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-         */
-
-        final byte nd_option__efo = 26;
-        final byte efo_num_8octets = 1;
-
-        ra.put(nd_option__efo)
-            .put(efo_num_8octets)
-            .putShort(asShort(0))
-            .putInt(0);
-    }
-
-    private static void putMtu(ByteBuffer ra, int mtu) {
-        /**
-            MTU
-
-             0                   1                   2                   3
-             0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |     Type      |    Length     |           Reserved            |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |                              MTU                              |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-        */
-        final byte nd_option_mtu = 5;
-        final byte mtu_num_8octs = 1;
-        ra.put(nd_option_mtu)
-            .put(mtu_num_8octs)
-            .putShort(asShort(0))
-            .putInt((mtu < IPV6_MIN_MTU) ? IPV6_MIN_MTU : mtu);
-    }
-
-    private static void putPio(ByteBuffer ra, IpPrefix ipp,
-                               int validTime, int preferredTime) {
-        /**
-            Prefix Information
-
-             0                   1                   2                   3
-             0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |     Type      |    Length     | Prefix Length |L|A| Reserved1 |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |                         Valid Lifetime                        |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |                       Preferred Lifetime                      |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |                           Reserved2                           |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |                                                               |
-            +                                                               +
-            |                                                               |
-            +                            Prefix                             +
-            |                                                               |
-            +                                                               +
-            |                                                               |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-        */
-        final int prefixLength = ipp.getPrefixLength();
-        if (prefixLength != 64) {
-            return;
-        }
-        final byte nd_option_pio = 3;
-        final byte pio_num_8octets = 4;
-
-        if (validTime < 0) validTime = 0;
-        if (preferredTime < 0) preferredTime = 0;
-        if (preferredTime > validTime) preferredTime = validTime;
-
-        final byte[] addr = ipp.getAddress().getAddress();
-        ra.put(nd_option_pio)
-            .put(pio_num_8octets)
-            .put(asByte(prefixLength))
-            .put(asByte(0xc0)) /* L & A set */
-            .putInt(validTime)
-            .putInt(preferredTime)
-            .putInt(0)
-            .put(addr);
-    }
-
-    private static void putRio(ByteBuffer ra, IpPrefix ipp) {
-        /**
-            Route Information Option
-
-             0                   1                   2                   3
-             0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |     Type      |    Length     | Prefix Length |Resvd|Prf|Resvd|
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |                        Route Lifetime                         |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |                   Prefix (Variable Length)                    |
-            .                                                               .
-            .                                                               .
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-         */
-        final int prefixLength = ipp.getPrefixLength();
-        if (prefixLength > 64) {
-            return;
-        }
-        final byte nd_option_rio = 24;
-        final byte rio_num_8octets = asByte(
-                (prefixLength == 0) ? 1 : (prefixLength <= 8) ? 2 : 3);
-
-        final byte[] addr = ipp.getAddress().getAddress();
-        ra.put(nd_option_rio)
-            .put(rio_num_8octets)
-            .put(asByte(prefixLength))
-            .put(asByte(0x18))
-            .putInt(DEFAULT_LIFETIME);
-
-        // Rely upon an IpPrefix's address being properly zeroed.
-        if (prefixLength > 0) {
-            ra.put(addr, 0, (prefixLength <= 64) ? 8 : 16);
-        }
-    }
-
-    private static void putRdnss(ByteBuffer ra, Set<Inet6Address> dnses, int lifetime) {
-        /**
-            Recursive DNS Server (RDNSS) Option
-
-             0                   1                   2                   3
-             0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |     Type      |     Length    |           Reserved            |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |                           Lifetime                            |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-            |                                                               |
-            :            Addresses of IPv6 Recursive DNS Servers            :
-            |                                                               |
-            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-         */
-
-        final HashSet<Inet6Address> filteredDnses = new HashSet<>();
-        for (Inet6Address dns : dnses) {
-            if ((new LinkAddress(dns, RFC7421_PREFIX_LENGTH)).isGlobalPreferred()) {
-                filteredDnses.add(dns);
-            }
-        }
-        if (filteredDnses.isEmpty()) return;
-
-        final byte nd_option_rdnss = 25;
-        final byte rdnss_num_8octets = asByte(dnses.size() * 2 + 1);
-        ra.put(nd_option_rdnss)
-            .put(rdnss_num_8octets)
-            .putShort(asShort(0))
-            .putInt(lifetime);
-
-        for (Inet6Address dns : filteredDnses) {
-            // NOTE: If the full of list DNS servers doesn't fit in the packet,
-            // this code will cause a buffer overflow and the RA won't include
-            // this instance of the option at all.
-            //
-            // TODO: Consider looking at ra.remaining() to determine how many
-            // DNS servers will fit, and adding only those.
-            ra.put(dns.getAddress());
-        }
-    }
-
-    private boolean createSocket() {
-        final int send_timout_ms = 300;
-
-        final int oldTag = TrafficStats.getAndSetThreadStatsTag(
-                TrafficStatsConstants.TAG_SYSTEM_NEIGHBOR);
-        try {
-            mSocket = Os.socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
-            // Setting SNDTIMEO is purely for defensive purposes.
-            Os.setsockoptTimeval(
-                    mSocket, SOL_SOCKET, SO_SNDTIMEO, StructTimeval.fromMillis(send_timout_ms));
-            SocketUtils.bindSocketToInterface(mSocket, mInterface.name);
-            TetheringUtils.setupRaSocket(mSocket, mInterface.index);
-        } catch (ErrnoException | IOException e) {
-            Log.e(TAG, "Failed to create RA daemon socket: " + e);
-            return false;
-        } finally {
-            TrafficStats.setThreadStatsTag(oldTag);
-        }
-
-        return true;
-    }
-
-    private void closeSocket() {
-        if (mSocket != null) {
-            try {
-                SocketUtils.closeSocket(mSocket);
-            } catch (IOException ignored) { }
-        }
-        mSocket = null;
-    }
-
-    private boolean isSocketValid() {
-        final FileDescriptor s = mSocket;
-        return (s != null) && s.valid();
-    }
-
-    private boolean isSuitableDestination(InetSocketAddress dest) {
-        if (mAllNodes.equals(dest)) {
-            return true;
-        }
-
-        final InetAddress destip = dest.getAddress();
-        return (destip instanceof Inet6Address)
-               && destip.isLinkLocalAddress()
-               && (((Inet6Address) destip).getScopeId() == mInterface.index);
-    }
-
-    private void maybeSendRA(InetSocketAddress dest) {
-        if (dest == null || !isSuitableDestination(dest)) {
-            dest = mAllNodes;
-        }
-
-        try {
-            synchronized (mLock) {
-                if (mRaLength < MIN_RA_HEADER_SIZE) {
-                    // No actual RA to send.
-                    return;
-                }
-                Os.sendto(mSocket, mRA, 0, mRaLength, 0, dest);
-            }
-            Log.d(TAG, "RA sendto " + dest.getAddress().getHostAddress());
-        } catch (ErrnoException | SocketException e) {
-            if (isSocketValid()) {
-                Log.e(TAG, "sendto error: " + e);
-            }
-        }
-    }
-
-    private final class UnicastResponder extends Thread {
-        private final InetSocketAddress mSolicitor = new InetSocketAddress(0);
-        // The recycled buffer for receiving Router Solicitations from clients.
-        // If the RS is larger than IPV6_MIN_MTU the packets are truncated.
-        // This is fine since currently only byte 0 is examined anyway.
-        private final byte[] mSolicitation = new byte[IPV6_MIN_MTU];
-
-        @Override
-        public void run() {
-            while (isSocketValid()) {
-                try {
-                    // Blocking receive.
-                    final int rval = Os.recvfrom(
-                            mSocket, mSolicitation, 0, mSolicitation.length, 0, mSolicitor);
-                    // Do the least possible amount of validation.
-                    if (rval < 1 || mSolicitation[0] != ICMPV6_ND_ROUTER_SOLICIT) {
-                        continue;
-                    }
-                } catch (ErrnoException | SocketException e) {
-                    if (isSocketValid()) {
-                        Log.e(TAG, "recvfrom error: " + e);
-                    }
-                    continue;
-                }
-
-                maybeSendRA(mSolicitor);
-            }
-        }
-    }
-
-    // TODO: Consider moving this to run on a provided Looper as a Handler,
-    // with WakeupMessage-style messages providing the timer driven input.
-    private final class MulticastTransmitter extends Thread {
-        private final Random mRandom = new Random();
-        private final AtomicInteger mUrgentAnnouncements = new AtomicInteger(0);
-
-        @Override
-        public void run() {
-            while (isSocketValid()) {
-                try {
-                    Thread.sleep(getNextMulticastTransmitDelayMs());
-                } catch (InterruptedException ignored) {
-                    // Stop sleeping, immediately send an RA, and continue.
-                }
-
-                maybeSendRA(mAllNodes);
-                synchronized (mLock) {
-                    if (mDeprecatedInfoTracker.decrementCounters()) {
-                        // At least one deprecated PIO has been removed;
-                        // reassemble the RA.
-                        assembleRaLocked();
-                    }
-                }
-            }
-        }
-
-        public void hup() {
-            // Set to one fewer that the desired number, because as soon as
-            // the thread interrupt is processed we immediately send an RA
-            // and mUrgentAnnouncements is not examined until the subsequent
-            // sleep interval computation (i.e. this way we send 3 and not 4).
-            mUrgentAnnouncements.set(MAX_URGENT_RTR_ADVERTISEMENTS - 1);
-            interrupt();
-        }
-
-        private int getNextMulticastTransmitDelaySec() {
-            boolean deprecationInProgress = false;
-            synchronized (mLock) {
-                if (mRaLength < MIN_RA_HEADER_SIZE) {
-                    // No actual RA to send; just sleep for 1 day.
-                    return DAY_IN_SECONDS;
-                }
-                deprecationInProgress = !mDeprecatedInfoTracker.isEmpty();
-            }
-
-            final int urgentPending = mUrgentAnnouncements.getAndDecrement();
-            if ((urgentPending > 0) || deprecationInProgress) {
-                return MIN_DELAY_BETWEEN_RAS_SEC;
-            }
-
-            return MIN_RTR_ADV_INTERVAL_SEC + mRandom.nextInt(
-                    MAX_RTR_ADV_INTERVAL_SEC - MIN_RTR_ADV_INTERVAL_SEC);
-        }
-
-        private long getNextMulticastTransmitDelayMs() {
-            return 1000 * (long) getNextMulticastTransmitDelaySec();
-        }
-    }
-}