Lazy init default netif

calimero-project · May 9, 2024 · b194a31 · b194a31
1 parent 78202c4
commit b194a31
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Showing 3 changed files with 18 additions and 14 deletions.
diff --git a/src/io/calimero/knxnetip/Discoverer.java b/src/io/calimero/knxnetip/Discoverer.java
@@ -723,7 +723,7 @@ private CompletableFuture<Result<SearchResponse>> receiveAsync(final DatagramCha
 		final InetSocketAddress local = (InetSocketAddress) dc.getLocalAddress();
 		final NetworkInterface netif;
 		if (local.getAddress().isAnyLocalAddress())
-			netif = Net.defaultNetif;
+			netif = Net.defaultNetif();
 		else
 			netif = NetworkInterface.getByInetAddress(local.getAddress());
 
@@ -765,7 +765,7 @@ private final class ReceiverLoop extends UdpSocketLooper implements Runnable
 			super(null, false, receiveBufferSize, 0, (int) timeout.toMillis());
 
 			final var mcastIf = dc.getOption(StandardSocketOptions.IP_MULTICAST_IF);
-			nif = mcastIf == null ? Net.defaultNetif : mcastIf;
+			nif = mcastIf == null ? Net.defaultNetif() : mcastIf;
 			this.localEndpoint = localEndpoint;
 			multicast = true;
 			server = null;

diff --git a/src/io/calimero/knxnetip/KNXnetIPRouting.java b/src/io/calimero/knxnetip/KNXnetIPRouting.java
@@ -316,7 +316,7 @@ public final int getHopCount()
 	public final NetworkInterface networkInterface() {
 		try {
 			final NetworkInterface netif = dc.getOption(StandardSocketOptions.IP_MULTICAST_IF);
-			return netif == null ? Net.defaultNetif : netif;
+			return netif == null ? Net.defaultNetif() : netif;
 		}
 		catch (final IOException e) {
 			throw new KnxRuntimeException("socket error getting network interface", e);
@@ -387,7 +387,7 @@ protected void init(final NetworkInterface netIf, final boolean useMulticastLoop
 					dcSysBcast.setOption(StandardSocketOptions.IP_MULTICAST_IF, setNetif);
 			}
 			else
-				setNetif = Net.defaultNetif;
+				setNetif = Net.defaultNetif();
 
 			logger.log(DEBUG, "join multicast group {0} on {1}", multicast.getHostAddress(), setNetif.getName());
 			dc.join(multicast, setNetif);
@@ -720,7 +720,7 @@ private void updateRoutingFlowControl(final RoutingBusy busy, final InetSocketAd
 
 	private boolean sentByUs(final InetSocketAddress sender) {
 		final var netif = networkInterface();
-		if (netif == Net.defaultNetif) {
+		if (netif == Net.defaultNetif()) {
 			// check addresses of all netifs, in case no outgoing mcast netif was configured
 			try {
 				return NetworkInterface.networkInterfaces().flatMap(NetworkInterface::inetAddresses)

diff --git a/src/io/calimero/knxnetip/Net.java b/src/io/calimero/knxnetip/Net.java
@@ -1,6 +1,6 @@
 /*
     Calimero 2 - A library for KNX network access
-    Copyright (c) 2021, 2023 B. Malinowsky
+    Copyright (c) 2021, 2024 B. Malinowsky
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -58,15 +58,19 @@ private Net() {}
 
 	private static final Logger logger = LogService.getLogger("io.calimero.knxnetip.Net");
 
-
-	static final NetworkInterface defaultNetif;
-	static {
-		try (var s = new MulticastSocket()) {
-			defaultNetif = s.getNetworkInterface();
-		}
-		catch (final IOException e) {
-			throw new ExceptionInInitializerError(e);
+	static NetworkInterface defaultNetif() {
+		class NetIf {
+			static final NetworkInterface defaultNetif;
+			static {
+				try (var s = new MulticastSocket()) {
+					defaultNetif = s.getNetworkInterface();
+				}
+				catch (final IOException e) {
+					throw new ExceptionInInitializerError(e);
+				}
+			}
 		}
+		return NetIf.defaultNetif;
 	}
 
 	// finds a local IPv4 address with its network prefix "matching" the remote address