fix: Avoid a couple cases where no NUIManager would cause trouble. (#4919)

Author: Cervator

engine/src/main/java/org/terasology/engine/core/modes/loadProcesses/StartServer.java

@@ -3,6 +3,8 @@
 
 package org.terasology.engine.core.modes.loadProcesses;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.terasology.engine.config.Config;
 import org.terasology.engine.context.Context;
 import org.terasology.engine.core.modes.SingleStepLoadProcess;
@@ -12,6 +14,7 @@
 import org.terasology.engine.rendering.nui.layers.mainMenu.MessagePopup;
 
 public class StartServer extends SingleStepLoadProcess {
+    private static final Logger logger = LoggerFactory.getLogger(StartServer.class);
 
     private final Context context;
     private final boolean dedicated;
@@ -36,8 +39,14 @@ public boolean step() {
             int port = config.getNetwork().getServerPort();
             context.get(NetworkSystem.class).host(port, dedicated);
         } catch (HostingFailedException e) {
-            context.get(NUIManager.class).pushScreen(MessagePopup.ASSET_URI, MessagePopup.class).setMessage("Failed to Host",
-                    e.getMessage() + " - Reverting to single player");
+            NUIManager nui = context.get(NUIManager.class);
+            if (nui != null) {
+                nui.pushScreen(MessagePopup.ASSET_URI, MessagePopup.class).setMessage("Failed to Host",
+                        e.getMessage() + " - Reverting to single player");
+            } else {
+                logger.error("Failed to Host. NUI was also unavailable for warning popup (headless?)", e);
+                throw new RuntimeException("Cannot host game successfully from likely headless start, terminating");
+            }
         }
         return true;
     }

engine/src/main/java/org/terasology/engine/network/internal/NetworkSystemImpl.java

@@ -179,13 +179,20 @@ public void host(int port, boolean dedicatedServer) throws HostingFailedExceptio
 
                 // enumerate all network interfaces that listen
                 Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
+
                 while (interfaces.hasMoreElements()) {
                     NetworkInterface ifc = interfaces.nextElement();
                     if (!ifc.isLoopback()) {
                         for (InterfaceAddress ifadr : ifc.getInterfaceAddresses()) {
-                            InetAddress adr = ifadr.getAddress();
-                            logger.info("Listening on network interface \"{}\", hostname \"{}\" ({})",
-                                    ifc.getDisplayName(), adr.getCanonicalHostName(), adr.getHostAddress());
+                            // Exclude interfaces with the following key words to avoid common virtual and otherwise unlikely useful nics
+                            // TODO: Make this configurable via config.cfg?
+                            if (ifc.getDisplayName().contains("VirtualBox") || ifc.getDisplayName().contains("ISATAP")) {
+                                logger.info("Skipping filtered interface name {}", ifc.getDisplayName());
+                            } else {
+                                InetAddress adr = ifadr.getAddress();
+                                logger.info("Listening on network interface \"{}\", hostname \"{}\" ({})",
+                                        ifc.getDisplayName(), adr.getCanonicalHostName(), adr.getHostAddress());
+                            }
                         }
                     }
                 }

engine/src/main/java/org/terasology/engine/rendering/nui/skin/UISkinFormat.java

@@ -129,6 +129,14 @@ private static class FamilyInfo extends StyleInfo {
 
         public void apply(UISkinBuilder builder) {
             super.apply(builder);
+
+            // Check if we actually have the NUI Manager available, this would for instance not be the case if starting a headless game server
+            NUIManager nui = CoreRegistry.get(NUIManager.class);
+            if (nui == null) {
+                logger.warn("NUIManager was unavailable, skipping UISkinFormat as not needed. This may or may not be a problem");
+                return;
+            }
+
             if (elements != null) {
                 for (Map.Entry<String, ElementInfo> entry : elements.entrySet()) {
                     WidgetLibrary library = CoreRegistry.get(NUIManager.class).getWidgetMetadataLibrary();