org.argeo.api.uuid/src/org/argeo/api/uuid/MacAddressUuidFactory.java

   1 package org.argeo.api.uuid;
   2
   3 import java.net.InetAddress;
   4 import java.net.NetworkInterface;
   5 import java.net.SocketException;
   6 import java.net.UnknownHostException;
   7 import java.util.Enumeration;
   8 import java.util.UUID;
   9
  10 /**
  11  * An {@link UUID} factory whose node id (for time based UUIDs) is the hardware
  12  * MAC address as specified in RFC4122.
  13  *
  14  * @see "https://datatracker.ietf.org/doc/html/rfc4122.html#section-4.1.6"
  15  */
  16 public class MacAddressUuidFactory extends ConcurrentUuidFactory {
  17         public MacAddressUuidFactory() {
  18                 this(0, localHardwareAddressAsNodeId());
  19         }
  20
  21         public MacAddressUuidFactory(long initialClockRange) {
  22                 this(initialClockRange, localHardwareAddressAsNodeId());
  23         }
  24
  25         public MacAddressUuidFactory(byte[] hardwareAddress) {
  26                 this(0, hardwareAddress);
  27         }
  28
  29         public MacAddressUuidFactory(long initialClockRange, byte[] hardwareAddress) {
  30                 super(initialClockRange, hardwareAddress);
  31         }
  32
  33         private static byte[] localHardwareAddressAsNodeId() {
  34                 InetAddress localHost;
  35                 try {
  36                         localHost = InetAddress.getLocalHost();
  37                         NetworkInterface nic = NetworkInterface.getByInetAddress(localHost);
  38                         if (nic != null && nic.getHardwareAddress() != null)
  39                                 return hardwareAddressToNodeId(nic);
  40                         Enumeration<NetworkInterface> netInterfaces = null;
  41                         netInterfaces = NetworkInterface.getNetworkInterfaces();
  42                         if (netInterfaces == null || !netInterfaces.hasMoreElements())
  43                                 throw new IllegalStateException("No interfaces");
  44                         while (netInterfaces.hasMoreElements()) {
  45                                 // TODO find out public/physical interfaces
  46                                 nic = netInterfaces.nextElement();
  47                                 if (nic.getHardwareAddress() != null)
  48                                         return hardwareAddressToNodeId(nic);
  49                         }
  50                         throw new IllegalStateException("No interfaces with a MAC address");
  51                 } catch (UnknownHostException | SocketException e) {
  52                         throw new IllegalStateException(e);
  53                 }
  54
  55         }
  56
  57         public static byte[] hardwareAddressToNodeId(NetworkInterface nic) throws IllegalStateException {
  58                 try {
  59                         byte[] hardwareAddress = nic.getHardwareAddress();
  60                         final int length = 6;
  61                         byte[] arr = new byte[length];
  62                         for (int i = 0; i < length; i++) {
  63                                 arr[i] = hardwareAddress[length - 1 - i];
  64                         }
  65                         return arr;
  66                 } catch (SocketException e) {
  67                         throw new IllegalStateException("Cannot retrieve hardware address from NIC", e);
  68                 }
  69         }
  70
  71 }