2019-07-15 01:27:49 -07:00

409 lines
12 KiB
Java

package com.limelight.nvstream.mdns;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.Inet4Address;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import javax.jmdns.JmmDNS;
import javax.jmdns.NetworkTopologyDiscovery;
import javax.jmdns.ServiceEvent;
import javax.jmdns.ServiceInfo;
import javax.jmdns.ServiceListener;
import javax.jmdns.impl.NetworkTopologyDiscoveryImpl;
import com.limelight.LimeLog;
public class MdnsDiscoveryAgent implements ServiceListener {
public static final String SERVICE_TYPE = "_nvstream._tcp.local.";
private MdnsDiscoveryListener listener;
private Thread discoveryThread;
private HashMap<InetAddress, MdnsComputer> computers = new HashMap<InetAddress, MdnsComputer>();
private HashSet<String> pendingResolution = new HashSet<String>();
// The resolver factory's instance member has a static lifetime which
// means our ref count and listener must be static also.
private static int resolverRefCount = 0;
private static HashSet<ServiceListener> listeners = new HashSet<ServiceListener>();
private static ServiceListener nvstreamListener = new ServiceListener() {
@Override
public void serviceAdded(ServiceEvent event) {
HashSet<ServiceListener> localListeners;
// Copy the listener set into a new set so we can invoke
// the callbacks without holding the listeners monitor the
// whole time.
synchronized (listeners) {
localListeners = new HashSet<ServiceListener>(listeners);
}
for (ServiceListener listener : localListeners) {
listener.serviceAdded(event);
}
}
@Override
public void serviceRemoved(ServiceEvent event) {
HashSet<ServiceListener> localListeners;
// Copy the listener set into a new set so we can invoke
// the callbacks without holding the listeners monitor the
// whole time.
synchronized (listeners) {
localListeners = new HashSet<ServiceListener>(listeners);
}
for (ServiceListener listener : localListeners) {
listener.serviceRemoved(event);
}
}
@Override
public void serviceResolved(ServiceEvent event) {
HashSet<ServiceListener> localListeners;
// Copy the listener set into a new set so we can invoke
// the callbacks without holding the listeners monitor the
// whole time.
synchronized (listeners) {
localListeners = new HashSet<ServiceListener>(listeners);
}
for (ServiceListener listener : localListeners) {
listener.serviceResolved(event);
}
}
};
public static class MyNetworkTopologyDiscovery extends NetworkTopologyDiscoveryImpl {
@Override
public boolean useInetAddress(NetworkInterface networkInterface, InetAddress interfaceAddress) {
// This is an copy of jmDNS's implementation, except we omit the multicast check, since
// it seems at least some devices lie about interfaces not supporting multicast when they really do.
try {
if (!networkInterface.isUp()) {
return false;
}
/*
if (!networkInterface.supportsMulticast()) {
return false;
}
*/
if (networkInterface.isLoopback()) {
return false;
}
return true;
} catch (Exception exception) {
return false;
}
}
};
static {
// Override jmDNS's default topology discovery class with ours
NetworkTopologyDiscovery.Factory.setClassDelegate(new NetworkTopologyDiscovery.Factory.ClassDelegate() {
@Override
public NetworkTopologyDiscovery newNetworkTopologyDiscovery() {
return new MyNetworkTopologyDiscovery();
}
});
}
private static JmmDNS referenceResolver() {
synchronized (MdnsDiscoveryAgent.class) {
JmmDNS instance = JmmDNS.Factory.getInstance();
if (++resolverRefCount == 1) {
// This will cause the listener to be invoked for known hosts immediately.
// JmDNS only supports one listener per service, so we have to do this here
// with a static listener.
instance.addServiceListener(SERVICE_TYPE, nvstreamListener);
}
return instance;
}
}
private static void dereferenceResolver() {
synchronized (MdnsDiscoveryAgent.class) {
if (--resolverRefCount == 0) {
try {
JmmDNS.Factory.close();
} catch (IOException e) {}
}
}
}
public MdnsDiscoveryAgent(MdnsDiscoveryListener listener) {
this.listener = listener;
}
private void handleResolvedServiceInfo(ServiceInfo info) {
synchronized (pendingResolution) {
pendingResolution.remove(info.getName());
}
try {
handleServiceInfo(info);
} catch (UnsupportedEncodingException e) {
// Invalid DNS response
LimeLog.info("mDNS: Invalid response for machine: "+info.getName());
return;
}
}
private Inet6Address getLocalAddress(Inet6Address[] addresses) {
for (Inet6Address addr : addresses) {
if (addr.isLinkLocalAddress() || addr.isSiteLocalAddress()) {
return addr;
}
// fc00::/7 - ULAs
else if ((addr.getAddress()[0] & 0xfe) == 0xfc) {
return addr;
}
}
return null;
}
private Inet6Address getLinkLocalAddress(Inet6Address[] addresses) {
for (Inet6Address addr : addresses) {
if (addr.isLinkLocalAddress()) {
LimeLog.info("Found link-local address: "+addr.getHostAddress());
return addr;
}
}
return null;
}
private Inet6Address getBestIpv6Address(Inet6Address[] addresses) {
// First try to find a link local address, so we can match the interface identifier
// with a global address (this will work for SLAAC but not DHCPv6).
Inet6Address linkLocalAddr = getLinkLocalAddress(addresses);
// We will try once to match a SLAAC interface suffix, then
// pick the first matching address
for (int tries = 0; tries < 2; tries++) {
// We assume the addresses are already sorted in descending order
// of preference from Bonjour.
for (Inet6Address addr : addresses) {
if (addr.isLinkLocalAddress() || addr.isSiteLocalAddress() || addr.isLoopbackAddress()) {
// Link-local, site-local, and loopback aren't global
LimeLog.info("Ignoring non-global address: "+addr.getHostAddress());
continue;
}
byte[] addrBytes = addr.getAddress();
// 2002::/16
if (addrBytes[0] == 0x20 && addrBytes[1] == 0x02) {
// 6to4 has horrible performance
LimeLog.info("Ignoring 6to4 address: "+addr.getHostAddress());
continue;
}
// 2001::/32
else if (addrBytes[0] == 0x20 && addrBytes[1] == 0x01 && addrBytes[2] == 0x00 && addrBytes[3] == 0x00) {
// Teredo also has horrible performance
LimeLog.info("Ignoring Teredo address: "+addr.getHostAddress());
continue;
}
// fc00::/7
else if ((addrBytes[0] & 0xfe) == 0xfc) {
// ULAs aren't global
LimeLog.info("Ignoring ULA: "+addr.getHostAddress());
continue;
}
// Compare the final 64-bit interface identifier and skip the address
// if it doesn't match our link-local address.
if (linkLocalAddr != null && tries == 0) {
boolean matched = true;
for (int i = 8; i < 16; i++) {
if (linkLocalAddr.getAddress()[i] != addr.getAddress()[i]) {
matched = false;
break;
}
}
if (!matched) {
LimeLog.info("Ignoring non-matching global address: "+addr.getHostAddress());
continue;
}
}
return addr;
}
}
return null;
}
private void handleServiceInfo(ServiceInfo info) throws UnsupportedEncodingException {
Inet4Address v4Addrs[] = info.getInet4Addresses();
Inet6Address v6Addrs[] = info.getInet6Addresses();
LimeLog.info("mDNS: "+info.getName()+" has "+v4Addrs.length+" IPv4 addresses");
LimeLog.info("mDNS: "+info.getName()+" has "+v6Addrs.length+" IPv6 addresses");
Inet6Address v6GlobalAddr = getBestIpv6Address(v6Addrs);
// Add a computer object for each IPv4 address reported by the PC
for (Inet4Address v4Addr : v4Addrs) {
synchronized (computers) {
MdnsComputer computer = new MdnsComputer(info.getName(), v4Addr, v6GlobalAddr);
if (computers.put(computer.getLocalAddress(), computer) == null) {
// This was a new entry
listener.notifyComputerAdded(computer);
}
}
}
// If there were no IPv4 addresses, use IPv6 for registration
if (v4Addrs.length == 0) {
Inet6Address v6LocalAddr = getLocalAddress(v6Addrs);
if (v6LocalAddr != null || v6GlobalAddr != null) {
MdnsComputer computer = new MdnsComputer(info.getName(), v6LocalAddr, v6GlobalAddr);
if (computers.put(v6LocalAddr != null ?
computer.getLocalAddress() : computer.getIpv6Address(), computer) == null) {
// This was a new entry
listener.notifyComputerAdded(computer);
}
}
}
}
public void startDiscovery(final int discoveryIntervalMs) {
// Kill any existing discovery before starting a new one
stopDiscovery();
// Add our listener to the set
synchronized (listeners) {
listeners.add(MdnsDiscoveryAgent.this);
}
discoveryThread = new Thread() {
@Override
public void run() {
// This may result in listener callbacks so we must register
// our listener first.
JmmDNS resolver = referenceResolver();
try {
while (!Thread.interrupted()) {
// Start an mDNS request
resolver.requestServiceInfo(SERVICE_TYPE, null, discoveryIntervalMs);
// Run service resolution again for pending machines
ArrayList<String> pendingNames;
synchronized (pendingResolution) {
pendingNames = new ArrayList<String>(pendingResolution);
}
for (String name : pendingNames) {
LimeLog.info("mDNS: Retrying service resolution for machine: "+name);
ServiceInfo[] infos = resolver.getServiceInfos(SERVICE_TYPE, name, 500);
if (infos != null && infos.length != 0) {
LimeLog.info("mDNS: Resolved (retry) with "+infos.length+" service entries");
for (ServiceInfo svcinfo : infos) {
handleResolvedServiceInfo(svcinfo);
}
}
}
// Wait for the next polling interval
try {
Thread.sleep(discoveryIntervalMs);
} catch (InterruptedException e) {
break;
}
}
}
finally {
// Dereference the resolver
dereferenceResolver();
}
}
};
discoveryThread.setName("mDNS Discovery Thread");
discoveryThread.start();
}
public void stopDiscovery() {
// Remove our listener from the set
synchronized (listeners) {
listeners.remove(MdnsDiscoveryAgent.this);
}
// If there's already a running thread, interrupt it
if (discoveryThread != null) {
discoveryThread.interrupt();
discoveryThread = null;
}
}
public List<MdnsComputer> getComputerSet() {
synchronized (computers) {
return new ArrayList<MdnsComputer>(computers.values());
}
}
@Override
public void serviceAdded(ServiceEvent event) {
LimeLog.info("mDNS: Machine appeared: "+event.getInfo().getName());
ServiceInfo info = event.getDNS().getServiceInfo(SERVICE_TYPE, event.getInfo().getName(), 500);
if (info == null) {
// This machine is pending resolution
synchronized (pendingResolution) {
pendingResolution.add(event.getInfo().getName());
}
return;
}
LimeLog.info("mDNS: Resolved (blocking)");
handleResolvedServiceInfo(info);
}
@Override
public void serviceRemoved(ServiceEvent event) {
LimeLog.info("mDNS: Machine disappeared: "+event.getInfo().getName());
Inet4Address v4Addrs[] = event.getInfo().getInet4Addresses();
for (Inet4Address addr : v4Addrs) {
synchronized (computers) {
MdnsComputer computer = computers.remove(addr);
if (computer != null) {
listener.notifyComputerRemoved(computer);
break;
}
}
}
Inet6Address v6Addrs[] = event.getInfo().getInet6Addresses();
for (Inet6Address addr : v6Addrs) {
synchronized (computers) {
MdnsComputer computer = computers.remove(addr);
if (computer != null) {
listener.notifyComputerRemoved(computer);
break;
}
}
}
}
@Override
public void serviceResolved(ServiceEvent event) {
// We handle this synchronously
}
}