Log network configuration at debug level

core/src/main/java/org/elasticsearch/common/network/IfConfig.java

@@ -0,0 +1,167 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.common.network;
+
+import org.elasticsearch.common.logging.ESLogger;
+import org.elasticsearch.common.logging.Loggers;
+
+import java.io.IOException;
+import java.net.Inet6Address;
+import java.net.InetAddress;
+import java.net.InterfaceAddress;
+import java.net.NetworkInterface;
+import java.net.SocketException;
+import java.util.List;
+import java.util.Locale;
+
+/** 
+ * Simple class to log {@code ifconfig}-style output at DEBUG logging.
+ */
+final class IfConfig {
+
+    private static final ESLogger logger = Loggers.getLogger(IfConfig.class);    
+    private static final String INDENT = "        ";
+    
+    /** log interface configuration at debug level, if its enabled */
+    static void logIfNecessary() {
+        if (logger.isDebugEnabled()) {
+            try {
+                doLogging();
+            } catch (IOException | SecurityException e) {
+                logger.warn("unable to gather network information", e);
+            }
+        }
+    }
+    
+    /** perform actual logging: might throw exception if things go wrong */
+    private static void doLogging() throws IOException {
+        StringBuilder msg = new StringBuilder();
+        for (NetworkInterface nic : NetworkUtils.getInterfaces()) {
+            msg.append(System.lineSeparator());
+
+            // ordinary name
+            msg.append(nic.getName());
+            msg.append(System.lineSeparator());
+            
+            // display name (e.g. on windows)
+            if (!nic.getName().equals(nic.getDisplayName())) {
+                msg.append(INDENT);
+                msg.append(nic.getDisplayName());
+                msg.append(System.lineSeparator());
+            }
+            
+            // addresses: v4 first, then v6
+            List<InterfaceAddress> addresses = nic.getInterfaceAddresses();
+            for (InterfaceAddress address : addresses) {
+                if (address.getAddress() instanceof Inet6Address == false) {
+                    msg.append(INDENT);
+                    msg.append(formatAddress(address));
+                    msg.append(System.lineSeparator());
+                }
+            }
+            
+            for (InterfaceAddress address : addresses) {
+                if (address.getAddress() instanceof Inet6Address) {
+                    msg.append(INDENT);
+                    msg.append(formatAddress(address));
+                    msg.append(System.lineSeparator());
+                }
+            }
+            
+            // hardware address
+            byte hardware[] = nic.getHardwareAddress();
+            if (hardware != null) {
+                msg.append(INDENT);
+                msg.append("hardware ");
+                for (int i = 0; i < hardware.length; i++) {
+                    if (i > 0) {
+                        msg.append(":");
+                    }
+                    msg.append(String.format(Locale.ROOT, "%02X", hardware[i]));
+                }
+                msg.append(System.lineSeparator());
+            }
+             
+            // attributes
+            msg.append(INDENT);
+            msg.append(formatFlags(nic));
+            msg.append(System.lineSeparator());
+        }
+        logger.debug("configuration:" + System.lineSeparator() + "{}", msg.toString());
+    }
+    
+    /** format internet address: java's default doesn't include everything useful */
+    private static String formatAddress(InterfaceAddress interfaceAddress) throws IOException {
+        StringBuilder sb = new StringBuilder();
+        
+        InetAddress address = interfaceAddress.getAddress();
+        if (address instanceof Inet6Address) {
+            sb.append("inet6 ");
+            sb.append(address.toString().substring(1));
+            sb.append(" prefixlen:");
+            sb.append(interfaceAddress.getNetworkPrefixLength());
+        } else {
+            sb.append("inet ");
+            sb.append(address.toString().substring(1));
+            int netmask = 0xFFFFFFFF << (32 - interfaceAddress.getNetworkPrefixLength());
+            sb.append(" netmask:" + InetAddress.getByAddress(new byte[] {
+                    (byte)(netmask >>> 24), 
+                    (byte)(netmask >>> 16 & 0xFF), 
+                    (byte)(netmask >>> 8 & 0xFF), 
+                    (byte)(netmask & 0xFF) 
+            }).toString().substring(1));
+            InetAddress broadcast = interfaceAddress.getBroadcast();
+            if (broadcast != null) {
+                sb.append(" broadcast:" + broadcast.toString().substring(1));
+            }
+        }
+        if (address.isLoopbackAddress()) {
+            sb.append(" scope:host");
+        } else if (address.isLinkLocalAddress()) {
+            sb.append(" scope:link");
+        } else if (address.isSiteLocalAddress()) {
+            sb.append(" scope:site");
+        }
+        return sb.toString();
+    }
+    
+    /** format network interface flags */
+    private static String formatFlags(NetworkInterface nic) throws SocketException {
+        StringBuilder flags = new StringBuilder();
+        if (nic.isUp()) {
+            flags.append("UP ");
+        }
+        if (nic.supportsMulticast()) {
+            flags.append("MULTICAST ");
+        }
+        if (nic.isLoopback()) {
+            flags.append("LOOPBACK ");
+        }
+        if (nic.isPointToPoint()) {
+            flags.append("POINTOPOINT ");
+        }
+        if (nic.isVirtual()) {
+            flags.append("VIRTUAL ");
+        }
+        flags.append("mtu:" + nic.getMTU());
+        flags.append(" index:" + nic.getIndex());
+        return flags.toString();
+    }
+}

core/src/main/java/org/elasticsearch/common/network/NetworkService.java

@@ -82,6 +82,7 @@ public class NetworkService extends AbstractComponent {
     @Inject
     public NetworkService(Settings settings) {
         super(settings);
+        IfConfig.logIfNecessary();
         InetSocketTransportAddress.setResolveAddress(settings.getAsBoolean("network.address.serialization.resolve", false));
     }