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Basic IPv6 Router Advertisement daemon

Browse Source 
Bug: 9580643
Change-Id: Iebd4d1f694699ffd4daf7d71e9b9d8f49e9b632f
This commit is contained in:
Erik Kline
2016-05-24 20:12:08 +09:00
parent 8158fbe83a
commit a3ca6bd3e0
3 changed files with 683 additions and 1 deletions
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9
core/java/android/net/NetworkUtils.java
View File

@ -45,12 +45,19 @@ public class NetworkUtils {
public native static void attachDhcpFilter(FileDescriptor fd) throws SocketException;
/**
* Attaches a socket filter that accepts ICMP6 router advertisement packets to the given socket.
* Attaches a socket filter that accepts ICMPv6 router advertisements to the given socket.
* @param fd the socket's {@link FileDescriptor}.
* @param packetType the hardware address type, one of ARPHRD_*.
*/
public native static void attachRaFilter(FileDescriptor fd, int packetType) throws SocketException;
/**
* Configures a socket for receiving ICMPv6 router solicitations and sending advertisements.
* @param fd the socket's {@link FileDescriptor}.
* @param ifIndex the interface index.
*/
public native static void setupRaSocket(FileDescriptor fd, int ifIndex) throws SocketException;
/**
* Binds the current process to the network designated by {@code netId}. All sockets created
* in the future (and not explicitly bound via a bound {@link SocketFactory} (see

94
core/jni/android_net_NetUtils.cpp
View File

@ -125,6 +125,99 @@ static void android_net_utils_attachRaFilter(JNIEnv *env, jobject clazz, jobject
}
}
static void android_net_utils_setupRaSocket(JNIEnv *env, jobject clazz, jobject javaFd,
jint ifIndex)
{
static const int kLinkLocalHopLimit = 255;
int fd = jniGetFDFromFileDescriptor(env, javaFd);
// Set an ICMPv6 filter that only passes Router Solicitations.
struct icmp6_filter rs_only;
ICMP6_FILTER_SETBLOCKALL(&rs_only);
ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &rs_only);
socklen_t len = sizeof(rs_only);
if (setsockopt(fd, IPPROTO_ICMPV6, ICMP6_FILTER, &rs_only, len) != 0) {
jniThrowExceptionFmt(env, "java/net/SocketException",
"setsockopt(ICMP6_FILTER): %s", strerror(errno));
return;
}
// Most/all of the rest of these options can be set via Java code, but
// because we're here on account of setting an icmp6_filter go ahead
// and do it all natively for now.
//
// TODO: Consider moving these out to Java.
// Set the multicast hoplimit to 255 (link-local only).
int hops = kLinkLocalHopLimit;
len = sizeof(hops);
if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &hops, len) != 0) {
jniThrowExceptionFmt(env, "java/net/SocketException",
"setsockopt(IPV6_MULTICAST_HOPS): %s", strerror(errno));
return;
}
// Set the unicast hoplimit to 255 (link-local only).
hops = kLinkLocalHopLimit;
len = sizeof(hops);
if (setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &hops, len) != 0) {
jniThrowExceptionFmt(env, "java/net/SocketException",
"setsockopt(IPV6_UNICAST_HOPS): %s", strerror(errno));
return;
}
// Explicitly disable multicast loopback.
int off = 0;
len = sizeof(off);
if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &off, len) != 0) {
jniThrowExceptionFmt(env, "java/net/SocketException",
"setsockopt(IPV6_MULTICAST_LOOP): %s", strerror(errno));
return;
}
// Specify the IPv6 interface to use for outbound multicast.
len = sizeof(ifIndex);
if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_IF, &ifIndex, len) != 0) {
jniThrowExceptionFmt(env, "java/net/SocketException",
"setsockopt(IPV6_MULTICAST_IF): %s", strerror(errno));
return;
}
// Additional options to be considered:
// - IPV6_TCLASS
// - IPV6_RECVPKTINFO
// - IPV6_RECVHOPLIMIT
// Bind to [::].
const struct sockaddr_in6 sin6 = {
.sin6_family = AF_INET6,
.sin6_port = 0,
.sin6_flowinfo = 0,
.sin6_addr = IN6ADDR_ANY_INIT,
.sin6_scope_id = 0,
};
auto sa = reinterpret_cast<const struct sockaddr *>(&sin6);
len = sizeof(sin6);
if (bind(fd, sa, len) != 0) {
jniThrowExceptionFmt(env, "java/net/SocketException",
"bind(IN6ADDR_ANY): %s", strerror(errno));
return;
}
// Join the all-routers multicast group, ff02::2%index.
struct ipv6_mreq all_rtrs = {
.ipv6mr_multiaddr = {{{0xff,2,0,0,0,0,0,0,0,0,0,0,0,0,0,2}}},
.ipv6mr_interface = ifIndex,
};
len = sizeof(all_rtrs);
if (setsockopt(fd, IPPROTO_IPV6, IPV6_JOIN_GROUP, &all_rtrs, len) != 0) {
jniThrowExceptionFmt(env, "java/net/SocketException",
"setsockopt(IPV6_JOIN_GROUP): %s", strerror(errno));
return;
}
}
static jboolean android_net_utils_bindProcessToNetwork(JNIEnv *env, jobject thiz, jint netId)
{
return (jboolean) !setNetworkForProcess(netId);
@ -173,6 +266,7 @@ static const JNINativeMethod gNetworkUtilMethods[] = {
{ "queryUserAccess", "(II)Z", (void*)android_net_utils_queryUserAccess },
{ "attachDhcpFilter", "(Ljava/io/FileDescriptor;)V", (void*) android_net_utils_attachDhcpFilter },
{ "attachRaFilter", "(Ljava/io/FileDescriptor;I)V", (void*) android_net_utils_attachRaFilter },
{ "setupRaSocket", "(Ljava/io/FileDescriptor;I)V", (void*) android_net_utils_setupRaSocket },
};
int register_android_net_NetworkUtils(JNIEnv* env)

581
services/net/java/android/net/ip/RouterAdvertisementDaemon.java Normal file
View File

@ -0,0 +1,581 @@
/*
* 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.system.OsConstants.*;
import android.net.IpPrefix;
import android.net.LinkAddress;
import android.net.LinkProperties;
import android.net.NetworkUtils;
import android.system.ErrnoException;
import android.system.Os;
import android.system.StructGroupReq;
import android.system.StructTimeval;
import android.util.Log;
import com.android.internal.annotations.GuardedBy;
import libcore.io.IoUtils;
import libcore.util.HexEncoding;
import java.io.FileDescriptor;
import java.io.InterruptedIOException;
import java.io.IOException;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.nio.BufferOverflowException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.ArrayList;
import java.util.HashSet;
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.
*
* - Support transmitting MAX_URGENT_RTR_ADVERTISEMENTS number of empty
* RAs with zero default router lifetime when transitioning from an
* advertising state to a non-advertising state.
*
* @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 IPV6_MIN_MTU = 1280;
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 static final byte[] ALL_NODES = new byte[] {
(byte) 0xff, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
};
private final String mIfName;
private final int mIfIndex;
private final byte[] mHwAddr;
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;
private volatile FileDescriptor mSocket;
private volatile MulticastTransmitter mMulticastTransmitter;
private volatile UnicastResponder mUnicastResponder;
public static class RaParams {
public boolean hasDefaultRoute;
public int mtu;
public HashSet<IpPrefix> prefixes;
public HashSet<Inet6Address> dnses;
public RaParams() {
hasDefaultRoute = false;
mtu = IPV6_MIN_MTU;
prefixes = new HashSet<IpPrefix>();
dnses = new HashSet<Inet6Address>();
}
public RaParams(RaParams other) {
hasDefaultRoute = other.hasDefaultRoute;
mtu = other.mtu;
prefixes = (HashSet) other.prefixes.clone();
dnses = (HashSet) other.dnses.clone();
}
}
public RouterAdvertisementDaemon(String ifname, int ifindex, byte[] hwaddr) {
mIfName = ifname;
mIfIndex = ifindex;
mHwAddr = hwaddr;
mAllNodes = new InetSocketAddress(getAllNodesForScopeId(mIfIndex), 0);
}
public void buildNewRa(RaParams params) {
if (params == null || params.prefixes.isEmpty()) {
// No RA to be served at this time.
clearRa();
return;
}
if (params.mtu < IPV6_MIN_MTU) {
params.mtu = IPV6_MIN_MTU;
}
final ByteBuffer ra = ByteBuffer.wrap(mRA);
ra.order(ByteOrder.BIG_ENDIAN);
synchronized (mLock) {
try {
putHeader(ra, params.hasDefaultRoute);
putSlla(ra, mHwAddr);
// 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);
putMtu(ra, params.mtu);
for (IpPrefix ipp : params.prefixes) {
putPio(ra, ipp);
}
if (params.dnses.size() > 0) {
putRdnss(ra, params.dnses);
}
mRaLength = ra.position();
} catch (BufferOverflowException e) {
Log.e(TAG, "Could not construct new RA: " + e);
mRaLength = 0;
return;
}
}
maybeNotifyMulticastTransmitter();
}
public boolean start() {
if (!createSocket()) {
return false;
}
mMulticastTransmitter = new MulticastTransmitter();
mMulticastTransmitter.start();
mUnicastResponder = new UnicastResponder();
mUnicastResponder.start();
return true;
}
public void stop() {
closeSocket();
mMulticastTransmitter = null;
mUnicastResponder = null;
}
private void clearRa() {
boolean notifySocket;
synchronized (mLock) {
notifySocket = (mRaLength != 0);
mRaLength = 0;
}
if (notifySocket) {
maybeNotifyMulticastTransmitter();
}
}
private void maybeNotifyMulticastTransmitter() {
final MulticastTransmitter m = mMulticastTransmitter;
if (m != null) {
m.hup();
}
}
private static Inet6Address getAllNodesForScopeId(int scopeId) {
try {
return Inet6Address.getByAddress("ff02::1", ALL_NODES, scopeId);
} catch (UnknownHostException uhe) {
Log.wtf(TAG, "Failed to construct ff02::1 InetAddress: " + uhe);
return null;
}
}
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) {
/**
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 ...
+-+-+-+-+-+-+-+-+-+-+-+-
*/
final byte DEFAULT_HOPLIMIT = 64;
ra.put(ICMPV6_ND_ROUTER_ADVERT)
.put(asByte(0))
.putShort(asShort(0))
.put(DEFAULT_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_8OCTETS = 1;
ra.put(ND_OPTION_MTU)
.put(MTU_NUM_8OCTETS)
.putShort(asShort(0))
.putInt(mtu);
}
private static void putPio(ByteBuffer ra, IpPrefix ipp) {
/**
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;
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(DEFAULT_LIFETIME)
.putInt(DEFAULT_LIFETIME)
.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) {
/**
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 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(DEFAULT_LIFETIME);
for (Inet6Address dns : dnses) {
ra.put(dns.getAddress());
}
}
private boolean createSocket() {
final int SEND_TIMEOUT_MS = 300;
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_TIMEOUT_MS));
Os.setsockoptIfreq(mSocket, SOL_SOCKET, SO_BINDTODEVICE, mIfName);
NetworkUtils.protectFromVpn(mSocket);
NetworkUtils.setupRaSocket(mSocket, mIfIndex);
} catch (ErrnoException | IOException e) {
Log.e(TAG, "Failed to create RA daemon socket: " + e);
return false;
}
return true;
}
private void closeSocket() {
if (mSocket != null) {
IoUtils.closeQuietly(mSocket);
}
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() == mIfIndex);
}
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 solicitor = new InetSocketAddress();
// 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 mSolication[] = new byte[IPV6_MIN_MTU];
@Override
public void run() {
while (isSocketValid()) {
try {
// Blocking receive.
final int rval = Os.recvfrom(
mSocket, mSolication, 0, mSolication.length, 0, solicitor);
// Do the least possible amount of validation.
if (rval < 1 || mSolication[0] != ICMPV6_ND_ROUTER_SOLICIT) {
continue;
}
} catch (ErrnoException | SocketException e) {
if (isSocketValid()) {
Log.e(TAG, "recvfrom error: " + e);
}
continue;
}
maybeSendRA(solicitor);
}
}
}
// 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);
}
}
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() {
synchronized (mLock) {
if (mRaLength < MIN_RA_HEADER_SIZE) {
// No actual RA to send; just sleep for 1 day.
return DAY_IN_SECONDS;
}
}
final int urgentPending = mUrgentAnnouncements.getAndDecrement();
if (urgentPending > 0) {
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();
}
}
}