Merge branch 'network-prefix-length' into 'master'

Use network prefix length to determine which addresses are connectable

Closes #1178

See merge request briar/briar!1230

bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPlugin.java

@@ -19,7 +19,7 @@ import java.io.IOException;
 import java.net.InetAddress;
 import java.net.Socket;
 import java.net.UnknownHostException;
-import java.util.Collection;
+import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
@@ -84,19 +84,19 @@ class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 	}
 
 	@Override
-	protected Collection<InetAddress> getLocalIpAddresses() {
+	protected List<InetAddress> getUsableLocalInetAddresses() {
 		// If the device doesn't have wifi, don't open any sockets
 		if (wifiManager == null) return emptyList();
-		// If we're connected to a wifi network, use that network
+		// If we're connected to a wifi network, return its address
 		WifiInfo info = wifiManager.getConnectionInfo();
-		if (info != null && info.getIpAddress() != 0)
+		if (info != null && info.getIpAddress() != 0) {
 			return singletonList(intToInetAddress(info.getIpAddress()));
+		}
 		// If we're running an access point, return its address
-		Collection<InetAddress> all = super.getLocalIpAddresses();
+		for (InetAddress addr : getLocalInetAddresses()) {
-		if (all.contains(WIFI_AP_ADDRESS))
+			if (addr.equals(WIFI_AP_ADDRESS)) return singletonList(addr);
-			return singletonList(WIFI_AP_ADDRESS);
+			if (addr.equals(WIFI_DIRECT_AP_ADDRESS)) return singletonList(addr);
-		if (all.contains(WIFI_DIRECT_AP_ADDRESS))
+		}
-			return singletonList(WIFI_DIRECT_AP_ADDRESS);
 		// No suitable addresses
 		return emptyList();
 	}
@@ -136,7 +136,7 @@ class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 	private void updateConnectionStatus() {
 		connectionStatusExecutor.execute(() -> {
 			if (!running) return;
-			Collection<InetAddress> addrs = getLocalIpAddresses();
+			List<InetAddress> addrs = getLocalInetAddresses();
 			if (addrs.contains(WIFI_AP_ADDRESS)
 					|| addrs.contains(WIFI_DIRECT_AP_ADDRESS)) {
 				LOG.info("Providing wifi hotspot");

bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/LanTcpPlugin.java

@@ -17,12 +17,11 @@ import java.io.IOException;
 import java.net.Inet4Address;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
+import java.net.InterfaceAddress;
 import java.net.ServerSocket;
 import java.net.Socket;
-import java.net.SocketAddress;
 import java.net.UnknownHostException;
 import java.util.ArrayList;
-import java.util.Comparator;
 import java.util.List;
 import java.util.Random;
 import java.util.concurrent.Executor;
@@ -51,9 +50,6 @@ class LanTcpPlugin extends TcpPlugin {
 
 	private static final Logger LOG = getLogger(LanTcpPlugin.class.getName());
 
-	private static final LanAddressComparator ADDRESS_COMPARATOR =
-			new LanAddressComparator();
-
 	private static final int MAX_ADDRESSES = 4;
 	private static final String SEPARATOR = ",";
 
@@ -111,28 +107,26 @@ class LanTcpPlugin extends TcpPlugin {
 	@Override
 	protected List<InetSocketAddress> getLocalSocketAddresses() {
 		TransportProperties p = callback.getLocalProperties();
-		int port = parsePortProperty(p.get(PROP_PORT));
+		int preferredPort = parsePortProperty(p.get(PROP_PORT));
 		String oldIpPorts = p.get(PROP_IP_PORTS);
 		List<InetSocketAddress> olds = parseSocketAddresses(oldIpPorts);
+
 		List<InetSocketAddress> locals = new ArrayList<>();
-		for (InetAddress local : getLocalIpAddresses()) {
+		List<InetSocketAddress> fallbacks = new ArrayList<>();
-			if (isAcceptableAddress(local)) {
+		for (InetAddress local : getUsableLocalInetAddresses()) {
-				// If we've used this address before, try to use the same port
+			// If we've used this address before, try to use the same port
-				boolean reused = false;
+			int port = preferredPort;
-				for (InetSocketAddress old : olds) {
+			for (InetSocketAddress old : olds) {
-					if (old.getAddress().equals(local)) {
+				if (old.getAddress().equals(local)) {
-						locals.add(new InetSocketAddress(local, old.getPort()));
+					port = old.getPort();
-						reused = true;
+					break;
-						break;
-					}
 				}
-				// Otherwise try to use our preferred port
-				if (!reused) locals.add(new InetSocketAddress(local, port));
-				// Fall back to any available port
-				locals.add(new InetSocketAddress(local, 0));
 			}
+			locals.add(new InetSocketAddress(local, port));
+			// Fall back to any available port
+			fallbacks.add(new InetSocketAddress(local, 0));
 		}
-		sort(locals, ADDRESS_COMPARATOR);
+		locals.addAll(fallbacks);
 		return locals;
 	}
 
@@ -155,6 +149,20 @@ class LanTcpPlugin extends TcpPlugin {
 		return addresses;
 	}
 
+	protected List<InetAddress> getUsableLocalInetAddresses() {
+		List<InterfaceAddress> ifAddrs =
+				new ArrayList<>(getLocalInterfaceAddresses());
+		// Prefer longer network prefixes
+		sort(ifAddrs, (a, b) ->
+				b.getNetworkPrefixLength() - a.getNetworkPrefixLength());
+		List<InetAddress> addrs = new ArrayList<>();
+		for (InterfaceAddress ifAddr : ifAddrs) {
+			InetAddress addr = ifAddr.getAddress();
+			if (isAcceptableAddress(addr)) addrs.add(addr);
+		}
+		return addrs;
+	}
+
 	@Override
 	protected void setLocalSocketAddress(InetSocketAddress a) {
 		String ipPort = getIpPortString(a);
@@ -218,55 +226,31 @@ class LanTcpPlugin extends TcpPlugin {
 	}
 
 	@Override
-	protected boolean isConnectable(InetSocketAddress remote) {
+	protected boolean isConnectable(InterfaceAddress local,
+			InetSocketAddress remote) {
 		if (remote.getPort() == 0) return false;
 		if (!isAcceptableAddress(remote.getAddress())) return false;
 		// Try to determine whether the address is on the same LAN as us
-		if (socket == null) return false;
+		byte[] localIp = local.getAddress().getAddress();
-		byte[] localIp = socket.getInetAddress().getAddress();
 		byte[] remoteIp = remote.getAddress().getAddress();
-		return addressesAreOnSameLan(localIp, remoteIp);
+		int prefixLength = local.getNetworkPrefixLength();
+		return areAddressesInSameNetwork(localIp, remoteIp, prefixLength);
 	}
 
 	// Package access for testing
-	boolean addressesAreOnSameLan(byte[] localIp, byte[] remoteIp) {
+	static boolean areAddressesInSameNetwork(byte[] localIp, byte[] remoteIp,
-		// 10.0.0.0/8
+			int prefixLength) {
-		if (isSlash8SiteLocal(localIp)) return isSlash8SiteLocal(remoteIp);
+		if (localIp.length != remoteIp.length) return false;
-		// 172.16.0.0/12
+		// Compare the first prefixLength bits of the addresses
-		if (isSlash12SiteLocal(localIp)) return isSlash12SiteLocal(remoteIp);
+		for (int i = 0; i < prefixLength; i++) {
-		// 192.168.0.0/16
+			int byteIndex = i >> 3;
-		if (isSlash16SiteLocal(localIp)) return isSlash16SiteLocal(remoteIp);
+			int bitIndex = i & 7; // 0 to 7
-		// 169.254.0.0/16
+			int mask = 128 >> bitIndex; // Select the bit at bitIndex
-		if (isSlash16LinkLocal(localIp)) return isSlash16LinkLocal(remoteIp);
+			if ((localIp[byteIndex] & mask) != (remoteIp[byteIndex] & mask)) {
-		// Unrecognised prefix
+				return false; // Addresses differ at bit i
-		return false;
+			}
-	}
+		}
-
+		return true;
-	private static boolean isSlash8SiteLocal(byte[] ipv4) {
-		return ipv4[0] == 10;
-	}
-
-	private static boolean isSlash12SiteLocal(byte[] ipv4) {
-		return ipv4[0] == (byte) 172 && (ipv4[1] & 0xF0) == 16;
-	}
-
-	private static boolean isSlash16SiteLocal(byte[] ipv4) {
-		return ipv4[0] == (byte) 192 && ipv4[1] == (byte) 168;
-	}
-
-	private static boolean isSlash16LinkLocal(byte[] ipv4) {
-		return ipv4[0] == (byte) 169 && ipv4[1] == (byte) 254;
-	}
-
-	// Returns the prefix length for a link-local or site-local address, or 0
-	// for any other address
-	private static int getPrefixLengthIfKnown(InetAddress addr) {
-		if (!(addr instanceof Inet4Address)) return 0;
-		byte[] ipv4 = addr.getAddress();
-		if (isSlash8SiteLocal(ipv4)) return 8;
-		if (isSlash12SiteLocal(ipv4)) return 12;
-		if (isSlash16SiteLocal(ipv4) || isSlash16LinkLocal(ipv4)) return 16;
-		return 0;
 	}
 
 	@Override
@@ -307,6 +291,12 @@ class LanTcpPlugin extends TcpPlugin {
 	public DuplexTransportConnection createKeyAgreementConnection(
 			byte[] commitment, BdfList descriptor) {
 		if (!isRunning()) return null;
+		ServerSocket ss = socket;
+		InterfaceAddress local = getLocalInterfaceAddress(ss.getInetAddress());
+		if (local == null) {
+			LOG.warning("No interface for key agreement server socket");
+			return null;
+		}
 		InetSocketAddress remote;
 		try {
 			remote = parseSocketAddress(descriptor);
@@ -314,12 +304,11 @@ class LanTcpPlugin extends TcpPlugin {
 			LOG.info("Invalid IP/port in key agreement descriptor");
 			return null;
 		}
-		if (!isConnectable(remote)) {
+		if (!isConnectable(local, remote)) {
 			if (LOG.isLoggable(INFO)) {
-				SocketAddress local = socket.getLocalSocketAddress();
 				LOG.info(scrubSocketAddress(remote) +
 						" is not connectable from " +
-						scrubSocketAddress(local));
+						scrubSocketAddress(ss.getLocalSocketAddress()));
 			}
 			return null;
 		}
@@ -327,7 +316,7 @@ class LanTcpPlugin extends TcpPlugin {
 			if (LOG.isLoggable(INFO))
 				LOG.info("Connecting to " + scrubSocketAddress(remote));
 			Socket s = createSocket();
-			s.bind(new InetSocketAddress(socket.getInetAddress(), 0));
+			s.bind(new InetSocketAddress(ss.getInetAddress(), 0));
 			s.connect(remote, connectionTimeout);
 			s.setSoTimeout(socketTimeout);
 			if (LOG.isLoggable(INFO))
@@ -377,19 +366,4 @@ class LanTcpPlugin extends TcpPlugin {
 			IoUtils.tryToClose(ss, LOG, WARNING);
 		}
 	}
-
-	static class LanAddressComparator implements Comparator<InetSocketAddress> {
-
-		@Override
-		public int compare(InetSocketAddress a, InetSocketAddress b) {
-			// Prefer addresses with non-zero ports
-			int aPort = a.getPort(), bPort = b.getPort();
-			if (aPort > 0 && bPort == 0) return -1;
-			if (aPort == 0 && bPort > 0) return 1;
-			// Prefer addresses with longer prefixes
-			int aPrefix = getPrefixLengthIfKnown(a.getAddress());
-			int bPrefix = getPrefixLengthIfKnown(b.getAddress());
-			return bPrefix - aPrefix;
-		}
-	}
 }

bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/TcpPlugin.java

@@ -19,10 +19,10 @@ import org.briarproject.bramble.util.IoUtils;
 import java.io.IOException;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
+import java.net.InterfaceAddress;
 import java.net.NetworkInterface;
 import java.net.ServerSocket;
 import java.net.Socket;
-import java.net.SocketAddress;
 import java.net.SocketException;
 import java.net.UnknownHostException;
 import java.util.ArrayList;
@@ -36,7 +36,6 @@ import java.util.regex.Pattern;
 
 import javax.annotation.Nullable;
 
-import static java.net.NetworkInterface.getNetworkInterfaces;
 import static java.util.Collections.emptyList;
 import static java.util.Collections.list;
 import static java.util.logging.Level.INFO;
@@ -88,7 +87,8 @@ abstract class TcpPlugin implements DuplexPlugin {
 	 * Returns true if connections to the given address can be attempted.
 	 */
 	@SuppressWarnings("BooleanMethodIsAlwaysInverted")
-	protected abstract boolean isConnectable(InetSocketAddress remote);
+	protected abstract boolean isConnectable(InterfaceAddress local,
+			InetSocketAddress remote);
 
 	TcpPlugin(Executor ioExecutor, Backoff backoff, PluginCallback callback,
 			int maxLatency, int maxIdleTime, int connectionTimeout) {
@@ -233,18 +233,23 @@ abstract class TcpPlugin implements DuplexPlugin {
 	@Override
 	public DuplexTransportConnection createConnection(TransportProperties p) {
 		if (!isRunning()) return null;
+		ServerSocket ss = socket;
+		InterfaceAddress local = getLocalInterfaceAddress(ss.getInetAddress());
+		if (local == null) {
+			LOG.warning("No interface for server socket");
+			return null;
+		}
 		for (InetSocketAddress remote : getRemoteSocketAddresses(p)) {
 			// Don't try to connect to our own address
 			if (!canConnectToOwnAddress() &&
-					remote.getAddress().equals(socket.getInetAddress())) {
+					remote.getAddress().equals(ss.getInetAddress())) {
 				continue;
 			}
-			if (!isConnectable(remote)) {
+			if (!isConnectable(local, remote)) {
 				if (LOG.isLoggable(INFO)) {
-					SocketAddress local = socket.getLocalSocketAddress();
 					LOG.info(scrubSocketAddress(remote) +
 							" is not connectable from " +
-							scrubSocketAddress(local));
+							scrubSocketAddress(ss.getLocalSocketAddress()));
 				}
 				continue;
 			}
@@ -252,7 +257,7 @@ abstract class TcpPlugin implements DuplexPlugin {
 				if (LOG.isLoggable(INFO))
 					LOG.info("Connecting to " + scrubSocketAddress(remote));
 				Socket s = createSocket();
-				s.bind(new InetSocketAddress(socket.getInetAddress(), 0));
+				s.bind(new InetSocketAddress(ss.getInetAddress(), 0));
 				s.connect(remote, connectionTimeout);
 				s.setSoTimeout(socketTimeout);
 				if (LOG.isLoggable(INFO))
@@ -267,6 +272,14 @@ abstract class TcpPlugin implements DuplexPlugin {
 		return null;
 	}
 
+	@Nullable
+	InterfaceAddress getLocalInterfaceAddress(InetAddress a) {
+		for (InterfaceAddress ifAddr : getLocalInterfaceAddresses()) {
+			if (ifAddr.getAddress().equals(a)) return ifAddr;
+		}
+		return null;
+	}
+
 	// Override for testing
 	protected boolean canConnectToOwnAddress() {
 		return false;
@@ -327,14 +340,27 @@ abstract class TcpPlugin implements DuplexPlugin {
 		throw new UnsupportedOperationException();
 	}
 
-	Collection<InetAddress> getLocalIpAddresses() {
+	List<InterfaceAddress> getLocalInterfaceAddresses() {
+		List<InterfaceAddress> addrs = new ArrayList<>();
+		for (NetworkInterface iface : getNetworkInterfaces()) {
+			addrs.addAll(iface.getInterfaceAddresses());
+		}
+		return addrs;
+	}
+
+	List<InetAddress> getLocalInetAddresses() {
+		List<InetAddress> addrs = new ArrayList<>();
+		for (NetworkInterface iface : getNetworkInterfaces()) {
+			addrs.addAll(list(iface.getInetAddresses()));
+		}
+		return addrs;
+	}
+
+	private List<NetworkInterface> getNetworkInterfaces() {
 		try {
-			Enumeration<NetworkInterface> ifaces = getNetworkInterfaces();
+			Enumeration<NetworkInterface> ifaces =
-			if (ifaces == null) return emptyList();
+					NetworkInterface.getNetworkInterfaces();
-			List<InetAddress> addrs = new ArrayList<>();
+			return ifaces == null ? emptyList() : list(ifaces);
-			for (NetworkInterface iface : list(ifaces))
-				addrs.addAll(list(iface.getInetAddresses()));
-			return addrs;
 		} catch (SocketException e) {
 			logException(LOG, WARNING, e);
 			return emptyList();

bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/WanTcpPlugin.java

@@ -10,6 +10,7 @@ import org.briarproject.bramble.api.properties.TransportProperties;
 import java.net.Inet4Address;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
+import java.net.InterfaceAddress;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.concurrent.Executor;
@@ -47,7 +48,7 @@ class WanTcpPlugin extends TcpPlugin {
 		TransportProperties p = callback.getLocalProperties();
 		InetSocketAddress old = parseSocketAddress(p.get(PROP_IP_PORT));
 		List<InetSocketAddress> addrs = new LinkedList<>();
-		for (InetAddress a : getLocalIpAddresses()) {
+		for (InetAddress a : getLocalInetAddresses()) {
 			if (isAcceptableAddress(a)) {
 				// If this is the old address, try to use the same port
 				if (old != null && old.getAddress().equals(a))
@@ -88,7 +89,8 @@ class WanTcpPlugin extends TcpPlugin {
 	}
 
 	@Override
-	protected boolean isConnectable(InetSocketAddress remote) {
+	protected boolean isConnectable(InterfaceAddress local,
+			InetSocketAddress remote) {
 		if (remote.getPort() == 0) return false;
 		return isAcceptableAddress(remote.getAddress());
 	}

bramble-core/src/test/java/org/briarproject/bramble/plugin/tcp/LanTcpPluginTest.java

@@ -10,7 +10,6 @@ import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.settings.Settings;
-import org.briarproject.bramble.plugin.tcp.LanTcpPlugin.LanAddressComparator;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.junit.Before;
 import org.junit.Test;
@@ -22,7 +21,6 @@ import java.net.InetSocketAddress;
 import java.net.NetworkInterface;
 import java.net.ServerSocket;
 import java.net.Socket;
-import java.util.Comparator;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -33,6 +31,7 @@ import static java.util.concurrent.Executors.newCachedThreadPool;
 import static java.util.concurrent.TimeUnit.SECONDS;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.COMMIT_LENGTH;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.TRANSPORT_ID_LAN;
+import static org.briarproject.bramble.plugin.tcp.LanTcpPlugin.areAddressesInSameNetwork;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
@@ -59,44 +58,62 @@ public class LanTcpPluginTest extends BrambleTestCase {
 	}
 
 	@Test
-	public void testAddressesAreOnSameLan() {
+	public void testAreAddressesInSameNetwork() {
-		// Local and remote in 10.0.0.0/8 should return true
+		// Local and remote in 10.0.0.0/8
-		assertTrue(plugin.addressesAreOnSameLan(makeAddress(10, 0, 0, 0),
+		assertTrue(areAddressesInSameNetwork(makeAddress(10, 0, 0, 0),
-				makeAddress(10, 255, 255, 255)));
+				makeAddress(10, 255, 255, 255), 8));
-		// Local and remote in 172.16.0.0/12 should return true
+		assertFalse(areAddressesInSameNetwork(makeAddress(10, 0, 0, 0),
-		assertTrue(plugin.addressesAreOnSameLan(makeAddress(172, 16, 0, 0),
+				makeAddress(10, 255, 255, 255), 9));
-				makeAddress(172, 31, 255, 255)));
+
-		// Local and remote in 192.168.0.0/16 should return true
+		// Local and remote in 172.16.0.0/12
-		assertTrue(plugin.addressesAreOnSameLan(makeAddress(192, 168, 0, 0),
+		assertTrue(areAddressesInSameNetwork(makeAddress(172, 16, 0, 0),
-				makeAddress(192, 168, 255, 255)));
+				makeAddress(172, 31, 255, 255), 12));
-		// Local and remote in 169.254.0.0/16 (link-local) should return true
+		assertFalse(areAddressesInSameNetwork(makeAddress(172, 16, 0, 0),
-		assertTrue(plugin.addressesAreOnSameLan(makeAddress(169, 254, 0, 0),
+				makeAddress(172, 31, 255, 255), 13));
-				makeAddress(169, 254, 255, 255)));
+
-		// Local and remote in different recognised prefixes should return false
+		// Local and remote in 192.168.0.0/16
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(10, 0, 0, 0),
+		assertTrue(areAddressesInSameNetwork(makeAddress(192, 168, 0, 0),
-				makeAddress(172, 31, 255, 255)));
+				makeAddress(192, 168, 255, 255), 16));
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(10, 0, 0, 0),
+		assertFalse(areAddressesInSameNetwork(makeAddress(192, 168, 0, 0),
-				makeAddress(192, 168, 255, 255)));
+				makeAddress(192, 168, 255, 255), 17));
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(172, 16, 0, 0),
+
-				makeAddress(10, 255, 255, 255)));
+		// Local and remote in 169.254.0.0/16
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(172, 16, 0, 0),
+		assertTrue(areAddressesInSameNetwork(makeAddress(169, 254, 0, 0),
-				makeAddress(192, 168, 255, 255)));
+				makeAddress(169, 254, 255, 255), 16));
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(192, 168, 0, 0),
+		assertFalse(areAddressesInSameNetwork(makeAddress(169, 254, 0, 0),
-				makeAddress(10, 255, 255, 255)));
+				makeAddress(169, 254, 255, 255), 17));
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(192, 168, 0, 0),
+
-				makeAddress(172, 31, 255, 255)));
+		// Local in 10.0.0.0/8, remote in a different network
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(169, 254, 0, 0),
+		assertFalse(areAddressesInSameNetwork(makeAddress(10, 0, 0, 0),
-				makeAddress(192, 168, 255, 255)));
+				makeAddress(172, 31, 255, 255), 8));
-		// Remote prefix unrecognised should return false
+		assertFalse(areAddressesInSameNetwork(makeAddress(10, 0, 0, 0),
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(10, 0, 0, 0),
+				makeAddress(192, 168, 255, 255), 8));
-				makeAddress(1, 2, 3, 4)));
+		assertFalse(areAddressesInSameNetwork(makeAddress(10, 0, 0, 0),
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(172, 16, 0, 0),
+				makeAddress(169, 254, 255, 255), 8));
-				makeAddress(1, 2, 3, 4)));
+
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(192, 168, 0, 0),
+		// Local in 172.16.0.0/12, remote in a different network
-				makeAddress(1, 2, 3, 4)));
+		assertFalse(areAddressesInSameNetwork(makeAddress(172, 16, 0, 0),
-		// Both prefixes unrecognised should return false
+				makeAddress(10, 255, 255, 255), 12));
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(1, 2, 3, 4),
+		assertFalse(areAddressesInSameNetwork(makeAddress(172, 16, 0, 0),
-				makeAddress(5, 6, 7, 8)));
+				makeAddress(192, 168, 255, 255), 12));
+		assertFalse(areAddressesInSameNetwork(makeAddress(172, 16, 0, 0),
+				makeAddress(169, 254, 255, 255), 12));
+
+		// Local in 192.168.0.0/16, remote in a different network
+		assertFalse(areAddressesInSameNetwork(makeAddress(192, 168, 0, 0),
+				makeAddress(10, 255, 255, 255), 16));
+		assertFalse(areAddressesInSameNetwork(makeAddress(192, 168, 0, 0),
+				makeAddress(172, 31, 255, 255), 16));
+		assertFalse(areAddressesInSameNetwork(makeAddress(192, 168, 0, 0),
+				makeAddress(169, 254, 255, 255), 16));
+
+		// Local in 169.254.0.0/16, remote in a different network
+		assertFalse(areAddressesInSameNetwork(makeAddress(169, 254, 0, 0),
+				makeAddress(10, 255, 255, 255), 16));
+		assertFalse(areAddressesInSameNetwork(makeAddress(169, 254, 0, 0),
+				makeAddress(172, 31, 255, 255), 16));
+		assertFalse(areAddressesInSameNetwork(makeAddress(169, 254, 0, 0),
+				makeAddress(192, 168, 255, 255), 16));
 	}
 
 	private byte[] makeAddress(int... parts) {
@@ -266,54 +283,12 @@ public class LanTcpPluginTest extends BrambleTestCase {
 		plugin.stop();
 	}
 
-	@Test
-	public void testComparatorPrefersNonZeroPorts() {
-		Comparator<InetSocketAddress> comparator = new LanAddressComparator();
-		InetSocketAddress nonZero = new InetSocketAddress("1.2.3.4", 1234);
-		InetSocketAddress zero = new InetSocketAddress("1.2.3.4", 0);
-
-		assertEquals(0, comparator.compare(nonZero, nonZero));
-		assertTrue(comparator.compare(nonZero, zero) < 0);
-
-		assertTrue(comparator.compare(zero, nonZero) > 0);
-		assertEquals(0, comparator.compare(zero, zero));
-	}
-
-	@Test
-	public void testComparatorPrefersLongerPrefixes() {
-		Comparator<InetSocketAddress> comparator = new LanAddressComparator();
-		InetSocketAddress prefix169 = new InetSocketAddress("169.254.0.1", 0);
-		InetSocketAddress prefix192 = new InetSocketAddress("192.168.0.1", 0);
-		InetSocketAddress prefix172 = new InetSocketAddress("172.16.0.1", 0);
-		InetSocketAddress prefix10 = new InetSocketAddress("10.0.0.1", 0);
-
-		assertEquals(0, comparator.compare(prefix169, prefix169));
-		assertEquals(0, comparator.compare(prefix169, prefix192));
-		assertTrue(comparator.compare(prefix169, prefix172) < 0);
-		assertTrue(comparator.compare(prefix169, prefix10) < 0);
-
-		assertEquals(0, comparator.compare(prefix192, prefix192));
-		assertEquals(0, comparator.compare(prefix192, prefix169));
-		assertTrue(comparator.compare(prefix192, prefix172) < 0);
-		assertTrue(comparator.compare(prefix192, prefix10) < 0);
-
-		assertTrue(comparator.compare(prefix172, prefix169) > 0);
-		assertTrue(comparator.compare(prefix172, prefix192) > 0);
-		assertEquals(0, comparator.compare(prefix172, prefix172));
-		assertTrue(comparator.compare(prefix172, prefix10) < 0);
-
-		assertTrue(comparator.compare(prefix10, prefix169) > 0);
-		assertTrue(comparator.compare(prefix10, prefix192) > 0);
-		assertTrue(comparator.compare(prefix10, prefix172) > 0);
-		assertEquals(0, comparator.compare(prefix10, prefix10));
-	}
-
-	@SuppressWarnings("BooleanMethodIsAlwaysInverted")
 	private boolean systemHasLocalIpv4Address() throws Exception {
 		for (NetworkInterface i : list(getNetworkInterfaces())) {
 			for (InetAddress a : list(i.getInetAddresses())) {
-				if (a instanceof Inet4Address)
+				if (a instanceof Inet4Address) {
 					return a.isLinkLocalAddress() || a.isSiteLocalAddress();
+				}
 			}
 		}
 		return false;