fix(commons): handle missing MAC addresses

hugegraph-commons/hugegraph-common/src/main/java/org/apache/hugegraph/license/MachineInfo.java

@@ -57,20 +57,19 @@ public List<String> getMacAddress() {
         if (this.macAddressList != null) {
             return this.macAddressList;
         }
-        this.macAddressList = new ArrayList<>();
+        List<String> list = new ArrayList<>();
         List<InetAddress> inetAddresses = this.getLocalAllInetAddress();
         if (inetAddresses != null && !inetAddresses.isEmpty()) {
             // Get the Mac address of all network interfaces
-            List<String> list = new ArrayList<>();
             Set<String> uniqueValues = new HashSet<>();
             for (InetAddress inetAddress : inetAddresses) {
-                String macByInetAddress = this.getMacByInetAddress(inetAddress);
-                if (uniqueValues.add(macByInetAddress)) {
+                String macByInetAddress = this.getMacByInetAddress(inetAddress, false);
+                if (macByInetAddress != null && uniqueValues.add(macByInetAddress)) {
                     list.add(macByInetAddress);
                 }
             }
-            this.macAddressList = list;
         }
+        this.macAddressList = list;
         return this.macAddressList;
     }
 
@@ -99,6 +98,10 @@ public List<InetAddress> getLocalAllInetAddress() {
     }
 
     public String getMacByInetAddress(InetAddress inetAddr) {
+        return this.getMacByInetAddress(inetAddr, true);
+    }
+
+    private String getMacByInetAddress(InetAddress inetAddr, boolean required) {
         byte[] mac;
         try {
             mac = NetworkInterface.getByInetAddress(inetAddr)
@@ -108,6 +111,12 @@ public String getMacByInetAddress(InetAddress inetAddr) {
                       "Failed to get mac address for inet address '%s'",
                       inetAddr));
         }
+        if (mac == null) {
+            if (required) {
+                throw new IllegalStateException("Network interface has no hardware address");
+            }
+            return null;
+        }
 
         StringBuilder sb = new StringBuilder();
         for (int i = 0; i < mac.length; i++) {

hugegraph-commons/hugegraph-common/src/test/java/org/apache/hugegraph/unit/license/MachineInfoTest.java

@@ -18,10 +18,14 @@
 package org.apache.hugegraph.unit.license;
 
 import java.net.InetAddress;
-import java.net.UnknownHostException;
+import java.net.NetworkInterface;
+import java.net.SocketException;
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.regex.Pattern;
 
+import org.junit.Assume;
 import org.junit.Test;
 
 import org.apache.hugegraph.license.MachineInfo;
@@ -73,15 +77,89 @@ public void testGetLocalAllInetAddress() {
     }
 
     @Test
-    public void testGetMacByInetAddress() throws UnknownHostException {
+    public void testGetMacByInetAddress() throws Exception {
         List<InetAddress> addressList = machineInfo.getLocalAllInetAddress();
         for (InetAddress address : addressList) {
-            String mac = machineInfo.getMacByInetAddress(address);
-            Assert.assertTrue(MAC_PATTERN.matcher(mac).matches());
+            byte[] hardwareAddress = NetworkInterface.getByInetAddress(address)
+                                                     .getHardwareAddress();
+            if (hardwareAddress == null) {
+                Throwable exception = Assert.assertThrows(RuntimeException.class,
+                                                          () -> machineInfo.getMacByInetAddress(address));
+                Assert.assertFalse(exception instanceof NullPointerException);
+            } else {
+                String mac = machineInfo.getMacByInetAddress(address);
+                Assert.assertTrue(MAC_PATTERN.matcher(mac).matches());
+            }
         }
         InetAddress address = InetAddress.getByAddress(new byte[]{0, 0, 0, 0});
-        Assert.assertThrows(RuntimeException.class, () -> {
-            machineInfo.getMacByInetAddress(address);
-        });
+        Throwable exception = Assert.assertThrows(RuntimeException.class,
+                                                  () -> machineInfo.getMacByInetAddress(address));
+        Assert.assertFalse(exception instanceof NullPointerException);
+    }
+
+    @Test
+    public void testGetMacAddressWithoutMac() throws SocketException {
+        InetAddress loopback = InetAddress.getLoopbackAddress();
+        Assume.assumeTrue(NetworkInterface.getByInetAddress(loopback)
+                                          .getHardwareAddress() == null);
+        MachineInfo info = new MachineInfo() {
+            @Override
+            public List<InetAddress> getLocalAllInetAddress() {
+                return Collections.singletonList(loopback);
+            }
+        };
+        Throwable exception = Assert.assertThrows(RuntimeException.class,
+                                                  () -> info.getMacByInetAddress(loopback));
+        Assert.assertFalse(exception instanceof NullPointerException);
+        Assert.assertEquals("Network interface has no hardware address", exception.getMessage());
+        List<String> addresses = info.getMacAddress();
+        Assert.assertTrue(addresses.isEmpty());
+        Assert.assertSame(addresses, info.getMacAddress());
+    }
+
+    @Test
+    public void testGetMacAddressSkipsMissingAndDuplicateMac() throws SocketException {
+        InetAddress loopback = InetAddress.getLoopbackAddress();
+        Assume.assumeTrue(NetworkInterface.getByInetAddress(loopback)
+                                          .getHardwareAddress() == null);
+        InetAddress addressWithMac = null;
+        for (InetAddress address : machineInfo.getLocalAllInetAddress()) {
+            if (NetworkInterface.getByInetAddress(address).getHardwareAddress() != null) {
+                addressWithMac = address;
+                break;
+            }
+        }
+        Assume.assumeNotNull(addressWithMac);
+        InetAddress address = addressWithMac;
+        MachineInfo info = new MachineInfo() {
+            @Override
+            public List<InetAddress> getLocalAllInetAddress() {
+                return Arrays.asList(loopback, address, loopback, address);
+            }
+        };
+        List<String> addresses = info.getMacAddress();
+        Assert.assertEquals(1, addresses.size());
+        Assert.assertTrue(addresses.contains(machineInfo.getMacByInetAddress(address)));
+        Assert.assertSame(addresses, info.getMacAddress());
+    }
+
+    @Test
+    public void testGetMacAddressRetriesAfterLookupFailure() {
+        RuntimeException failure = new RuntimeException("Controlled interface enumeration failure");
+        int[] attempts = {0};
+        MachineInfo info = new MachineInfo() {
+            @Override
+            public List<InetAddress> getLocalAllInetAddress() {
+                if (++attempts[0] == 1) {
+                    throw failure;
+                }
+                return Collections.emptyList();
+            }
+        };
+        Assert.assertSame(failure, Assert.assertThrows(RuntimeException.class, info::getMacAddress));
+        List<String> addresses = info.getMacAddress();
+        Assert.assertTrue(addresses.isEmpty());
+        Assert.assertSame(addresses, info.getMacAddress());
+        Assert.assertEquals(2, attempts[0]);
     }
 }