mirror of
https://code.briarproject.org/briar/briar.git
synced 2026-02-12 10:49:06 +01:00
Symmetric invitation protocol for the LAN plugin.
See issue #development-tasks/20: some devices can send but not receive multicast packets.
This commit is contained in:
akwizgran
@@ -14,12 +14,14 @@ import java.net.ServerSocket;
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import java.net.Socket;
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import java.net.SocketAddress;
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import java.net.SocketException;
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import java.net.SocketTimeoutException;
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import java.net.UnknownHostException;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.List;
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import java.util.concurrent.CountDownLatch;
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import java.util.concurrent.Executor;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.atomic.AtomicReference;
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import java.util.logging.Logger;
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import net.sf.briar.api.TransportId;
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@@ -122,69 +124,98 @@ class LanTcpPlugin extends TcpPlugin {
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public DuplexTransportConnection sendInvitation(PseudoRandom r,
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long timeout) {
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if(!running) return null;
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// Use the invitation code to choose the group address and port
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InetSocketAddress mcast = chooseMulticastGroup(r);
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// Bind a multicast socket for receiving packets
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// Use the invitation codes to generate the group address and port
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InetSocketAddress group = chooseMulticastGroup(r);
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// Bind a multicast socket for sending and receiving packets
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InetAddress iface = null;
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MulticastSocket ms = null;
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try {
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InetAddress iface = chooseInterface();
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iface = chooseInvitationInterface();
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if(iface == null) return null;
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ms = new MulticastSocket(mcast.getPort());
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ms = new MulticastSocket(group.getPort());
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ms.setInterface(iface);
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ms.joinGroup(mcast.getAddress());
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ms.joinGroup(group.getAddress());
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} catch(IOException e) {
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if(LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
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if(ms != null) tryToClose(ms, mcast.getAddress());
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if(ms != null) tryToClose(ms, group.getAddress());
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return null;
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}
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if(LOG.isLoggable(INFO)) LOG.info("Listening for multicast packets");
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// Listen until a valid packet is received or the timeout occurs
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// Bind a server socket for receiving invitation connections
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ServerSocket ss = null;
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try {
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ss = new ServerSocket();
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ss.bind(new InetSocketAddress(iface, 0));
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} catch(IOException e) {
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if(LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
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if(ss != null) tryToClose(ss);
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return null;
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}
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// Start the listener threads
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SocketReceiver receiver = new SocketReceiver();
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new MulticastListenerThread(receiver, ms, iface).start();
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new TcpListenerThread(receiver, ss).start();
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// Send packets until a connection is made or we run out of time
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byte[] buffer = new byte[2];
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ByteUtils.writeUint16(ss.getLocalPort(), buffer, 0);
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DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
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packet.setAddress(group.getAddress());
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packet.setPort(group.getPort());
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long now = clock.currentTimeMillis();
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long end = now + timeout;
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try {
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while(now < end) {
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while(now < end && running) {
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// Send a packet
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if(LOG.isLoggable(INFO)) LOG.info("Sending multicast packet");
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ms.send(packet);
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// Wait for an incoming or outgoing connection
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try {
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ms.setSoTimeout((int) (end - now));
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ms.receive(packet);
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byte[] b = packet.getData();
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int off = packet.getOffset();
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int len = packet.getLength();
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int port = parsePacket(b, off, len);
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if(LOG.isLoggable(INFO)){
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String addr = getHostAddress(packet.getAddress());
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LOG.info("Received a packet from " + addr + ":" + port);
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}
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if(port >= 32768 && port < 65536) {
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try {
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// Connect back on the advertised TCP port
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Socket s = new Socket(packet.getAddress(), port);
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if(LOG.isLoggable(INFO)) LOG.info("Connected back");
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return new TcpTransportConnection(this, s);
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} catch(IOException e) {
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if(LOG.isLoggable(WARNING))
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LOG.log(WARNING, e.toString(), e);
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}
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}
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} catch(SocketTimeoutException e) {
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if(LOG.isLoggable(INFO)) LOG.info("Timed out");
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break;
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Socket s = receiver.waitForSocket(MULTICAST_INTERVAL);
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if(s != null) return new TcpTransportConnection(this, s);
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} catch(InterruptedException e) {
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if(LOG.isLoggable(INFO))
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LOG.info("Interrupted while exchanging invitations");
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Thread.currentThread().interrupt();
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return null;
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}
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now = clock.currentTimeMillis();
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if(!running) return null;
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}
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if(LOG.isLoggable(INFO))
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LOG.info("Timeout while sending invitation");
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} catch(IOException e) {
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if(LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
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} finally {
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tryToClose(ms, mcast.getAddress());
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// Closing the sockets will terminate the listener threads
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tryToClose(ms, group.getAddress());
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tryToClose(ss);
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}
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return null;
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}
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private InetAddress chooseInterface() throws IOException {
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private InetSocketAddress chooseMulticastGroup(PseudoRandom r) {
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byte[] b = r.nextBytes(5);
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// The group address is 239.random.random.random, excluding 0 and 255
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byte[] group = new byte[4];
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group[0] = (byte) 239;
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group[1] = legalAddressByte(b[0]);
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group[2] = legalAddressByte(b[1]);
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group[3] = legalAddressByte(b[2]);
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// The port is random in the range 32768 - 65535, inclusive
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int port = ByteUtils.readUint16(b, 3);
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if(port < 32768) port += 32768;
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InetAddress address;
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try {
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address = InetAddress.getByAddress(group);
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} catch(UnknownHostException badAddressLength) {
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throw new RuntimeException(badAddressLength);
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}
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return new InetSocketAddress(address, port);
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}
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private byte legalAddressByte(byte b) {
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if(b == 0) return 1;
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if(b == (byte) 255) return (byte) 254;
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return b;
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}
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private InetAddress chooseInvitationInterface() throws IOException {
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List<NetworkInterface> ifaces =
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Collections.list(NetworkInterface.getNetworkInterfaces());
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// Prefer an interface with a link-local or site-local address
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@@ -215,107 +246,128 @@ class LanTcpPlugin extends TcpPlugin {
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ms.close();
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}
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private InetSocketAddress chooseMulticastGroup(PseudoRandom r) {
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byte[] b = r.nextBytes(5);
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// The group address is 239.random.random.random, excluding 0 and 255
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byte[] group = new byte[4];
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group[0] = (byte) 239;
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group[1] = legalAddressByte(b[0]);
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group[2] = legalAddressByte(b[1]);
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group[3] = legalAddressByte(b[2]);
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// The port is random in the range 32768 - 65535, inclusive
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int port = ByteUtils.readUint16(b, 3);
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if(port < 32768) port += 32768;
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InetAddress address;
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try {
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address = InetAddress.getByAddress(group);
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} catch(UnknownHostException badAddressLength) {
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throw new RuntimeException(badAddressLength);
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}
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return new InetSocketAddress(address, port);
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}
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private byte legalAddressByte(byte b) {
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if(b == 0) return 1;
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if(b == (byte) 255) return (byte) 254;
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return b;
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}
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private int parsePacket(byte[] b, int off, int len) {
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if(len != 2) return 0;
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return ByteUtils.readUint16(b, off);
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}
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public DuplexTransportConnection acceptInvitation(PseudoRandom r,
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long timeout) {
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if(!running) return null;
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// Use the invitation code to choose the group address and port
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InetSocketAddress mcast = chooseMulticastGroup(r);
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// Bind a TCP socket for receiving connections
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ServerSocket ss = null;
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try {
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InetAddress iface = chooseInterface();
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if(iface == null) return null;
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ss = new ServerSocket();
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ss.bind(new InetSocketAddress(iface, 0));
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} catch(IOException e) {
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if(LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
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if(ss != null) tryToClose(ss);
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return null;
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// FIXME
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return sendInvitation(r, timeout);
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}
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private static class SocketReceiver {
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private final CountDownLatch latch = new CountDownLatch(1);
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private final AtomicReference<Socket> socket =
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new AtomicReference<Socket>();
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private boolean setSocket(Socket s) {
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if(socket.compareAndSet(null, s)) {
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latch.countDown();
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return true;
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}
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return false;
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}
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// Bind a multicast socket for sending packets
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MulticastSocket ms = null;
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try {
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InetAddress iface = chooseInterface();
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if(iface == null) return null;
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ms = new MulticastSocket();
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ms.setInterface(iface);
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} catch(IOException e) {
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if(LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
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if(ms != null) ms.close();
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tryToClose(ss);
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return null;
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private Socket waitForSocket(long timeout) throws InterruptedException {
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latch.await(timeout, TimeUnit.MILLISECONDS);
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return socket.get();
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}
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// Send packets until a connection is received or the timeout expires
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byte[] buffer = new byte[2];
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ByteUtils.writeUint16(ss.getLocalPort(), buffer, 0);
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DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
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packet.setAddress(mcast.getAddress());
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packet.setPort(mcast.getPort());
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long now = clock.currentTimeMillis();
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long end = now + timeout;
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long nextPacket = now + MULTICAST_INTERVAL;
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try {
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while(now < end) {
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try {
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int wait = (int) (Math.min(end, nextPacket) - now);
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ss.setSoTimeout(wait < 1 ? 1 : wait);
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}
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private class MulticastListenerThread extends Thread {
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private final SocketReceiver receiver;
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private final MulticastSocket multicastSocket;
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private final InetAddress localAddress;
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private MulticastListenerThread(SocketReceiver receiver,
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MulticastSocket multicastSocket, InetAddress localAddress) {
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this.receiver = receiver;
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this.multicastSocket = multicastSocket;
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this.localAddress = localAddress;
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}
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@Override
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public void run() {
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if(LOG.isLoggable(INFO))
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LOG.info("Listening for multicast packets");
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// Listen until a valid packet is received or the socket is closed
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byte[] buffer = new byte[2];
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DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
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try {
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while(running) {
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multicastSocket.receive(packet);
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if(LOG.isLoggable(INFO))
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LOG.info("Listening for TCP connections: " + wait);
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Socket s = ss.accept();
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if(LOG.isLoggable(INFO))
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LOG.info("Received a TCP connection");
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return new TcpTransportConnection(this, s);
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} catch(SocketTimeoutException e) {
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now = clock.currentTimeMillis();
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if(now < end) {
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if(LOG.isLoggable(INFO))
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LOG.info("Sending multicast packet");
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ms.send(packet);
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now = clock.currentTimeMillis();
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nextPacket = now + MULTICAST_INTERVAL;
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}
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LOG.info("Received multicast packet");
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parseAndConnectBack(packet);
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}
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if(!running) return null;
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} catch(IOException e) {
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// This is expected when the socket is closed
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if(LOG.isLoggable(INFO)) LOG.log(INFO, e.toString(), e);
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}
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}
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private void parseAndConnectBack(DatagramPacket packet) {
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InetAddress addr = packet.getAddress();
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if(addr.equals(localAddress)) {
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if(LOG.isLoggable(INFO)) LOG.info("Ignoring own packet");
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return;
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}
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byte[] b = packet.getData();
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int off = packet.getOffset();
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int len = packet.getLength();
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if(len != 2) {
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if(LOG.isLoggable(INFO)) LOG.info("Invalid length: " + len);
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return;
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}
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int port = ByteUtils.readUint16(b, off);
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if(port < 32768 || port >= 65536) {
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if(LOG.isLoggable(INFO)) LOG.info("Invalid port: " + port);
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return;
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}
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if(LOG.isLoggable(INFO))
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LOG.info("Timeout while accepting invitation");
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} catch(IOException e) {
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if(LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
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} finally {
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ms.close();
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tryToClose(ss);
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LOG.info("Packet from " + getHostAddress(addr) + ":" + port);
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try {
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// Connect back on the advertised TCP port
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Socket s = new Socket(addr, port);
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if(LOG.isLoggable(INFO)) LOG.info("Outgoing connection");
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if(!receiver.setSocket(s)) {
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if(LOG.isLoggable(INFO))
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LOG.info("Closing redundant connection");
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s.close();
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}
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} catch(IOException e) {
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if(LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
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}
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}
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return null;
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}
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}
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private class TcpListenerThread extends Thread {
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private final SocketReceiver receiver;
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private final ServerSocket serverSocket;
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private TcpListenerThread(SocketReceiver receiver,
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ServerSocket serverSocket) {
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this.receiver = receiver;
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this.serverSocket = serverSocket;
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}
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@Override
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public void run() {
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if(LOG.isLoggable(INFO))
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LOG.info("Listening for invitation connections");
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// Listen until a connection is received or the socket is closed
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try {
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Socket s = serverSocket.accept();
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if(LOG.isLoggable(INFO)) LOG.info("Incoming connection");
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if(!receiver.setSocket(s)) {
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if(LOG.isLoggable(INFO))
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LOG.info("Closing redundant connection");
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s.close();
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}
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} catch(IOException e) {
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// This is expected when the socket is closed
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if(LOG.isLoggable(INFO)) LOG.log(INFO, e.toString(), e);
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}
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}
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}
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}
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Reference in New Issue
Block a user