[New] Added new NetworkHelper.streamStrolchNetworkInterface()

This now streams over all interfaces, no matter if it is running or not.

utils/src/main/java/li/strolch/utils/helper/NetworkHelper.java

@@ -1,12 +1,19 @@
 package li.strolch.utils.helper;
 
-import java.net.Inet4Address;
-import java.net.InetAddress;
-import java.net.NetworkInterface;
-import java.net.SocketException;
-import java.util.ArrayList;
-import java.util.Enumeration;
-import java.util.List;
+import java.io.File;
+import java.io.IOException;
+import java.net.*;
+import java.nio.file.Path;
+import java.util.*;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
+import static java.nio.file.Files.readAllLines;
+import static java.nio.file.Files.readString;
+import static java.util.Spliterator.ORDERED;
+import static java.util.Spliterators.spliteratorUnknownSize;
 
 public class NetworkHelper {
 
@@ -33,6 +40,15 @@ public class NetworkHelper {
 		return inet4Addresses;
 	}
 
+	public static String formatMacAddress(NetworkInterface networkInterface) {
+		try {
+			return formatMacAddress(networkInterface.getHardwareAddress());
+		} catch (SocketException e) {
+			throw new IllegalStateException(
+					"Failed to get hardware address for network interface " + networkInterface.getDisplayName(), e);
+		}
+	}
+
 	public static String formatMacAddress(byte[] bytes) {
 		StringBuilder sb = new StringBuilder(17);
 		for (byte b : bytes) {
@@ -42,4 +58,83 @@ public class NetworkHelper {
 		}
 		return sb.toString();
 	}
+
+	public static void main(String[] args) throws IOException {
+
+		Stream<StrolchNetworkInterface> interfaceStream = streamStrolchNetworkInterface();
+
+		interfaceStream.forEach(t -> System.out.printf("%20s: %s%n", t.name(), t.hwAddress()));
+	}
+
+	public static Stream<StrolchNetworkInterface> streamStrolchNetworkInterface() {
+
+		if (!System.getProperty("os.name").equals("Linux")) {
+			Enumeration<NetworkInterface> interfaces = null;
+			try {
+				interfaces = NetworkInterface.getNetworkInterfaces();
+			} catch (SocketException e) {
+				throw new IllegalStateException("Failed to read network interfaces ", e);
+			}
+			return StreamSupport.stream(spliteratorUnknownSize(interfaces.asIterator(), ORDERED), false).map(ni -> {
+				try {
+					List<InetAddress> addresses = Collections.list(ni.getInetAddresses());
+					if (addresses.isEmpty())
+						addresses = List.of(Inet4Address.getByName("0.0.0.0"));
+					return new StrolchNetworkInterface(ni.getName(), formatMacAddress(ni), addresses);
+				} catch (UnknownHostException e) {
+					throw new IllegalStateException("Failed to read information for device " + ni.getName(), e);
+				}
+			});
+		}
+
+		// Read all available device names
+		Pattern pattern = Pattern.compile("^ *(.*):");
+		List<String> kernelInterfaceLines;
+		try {
+			kernelInterfaceLines = readAllLines(Path.of("/proc/net/dev"));
+		} catch (IOException e) {
+			throw new IllegalStateException("Failed to read /proc/net/dev", e);
+		}
+
+		return kernelInterfaceLines.stream().map(line -> {
+			Matcher m = pattern.matcher(line);
+			if (m.find())
+				return m.group(1).trim();
+			return null;
+		}).filter(Objects::nonNull).filter(device -> {
+			if (device.startsWith("br-"))
+				return false;
+			if (device.startsWith("veth"))
+				return false;
+			if (device.startsWith("docker"))
+				return false;
+			return true;
+		}).map(device -> {
+			try {
+				String hwAddress = readString(Path.of("/sys/class/net/" + device + "/address")).trim();
+				File operStateFile = new File("/sys/class/net/" + device + "/operstate");
+				File carrierFile = new File("/sys/class/net/" + device + "/carrier");
+				boolean hasNoCarrier;
+				if (operStateFile.exists()) {
+					hasNoCarrier = operStateFile.exists() && readString(operStateFile.toPath()).trim().equals("down");
+				} else {
+					hasNoCarrier = readString(carrierFile.toPath()).trim().equals("0");
+				}
+				if (hasNoCarrier)
+					return new StrolchNetworkInterface(device, hwAddress, List.of(Inet4Address.getByName("0.0.0.0")));
+
+				NetworkInterface ni = NetworkInterface.getByName(device);
+				if (ni.isLoopback() || ni.isPointToPoint() || ni.isVirtual())
+					return null;
+
+				List<InetAddress> addresses = Collections.list(ni.getInetAddresses());
+				if (addresses.isEmpty())
+					addresses = List.of(Inet4Address.getByName("0.0.0.0"));
+				return new StrolchNetworkInterface(ni.getName(), hwAddress, addresses);
+
+			} catch (IOException e) {
+				throw new IllegalStateException("Failed to read information for device " + device, e);
+			}
+		}).filter(Objects::nonNull);
+	}
 }

utils/src/main/java/li/strolch/utils/helper/StrolchNetworkInterface.java

@@ -0,0 +1,12 @@
+package li.strolch.utils.helper;
+
+import java.net.InetAddress;
+import java.util.List;
+
+public record StrolchNetworkInterface(String name, String hwAddress, List<InetAddress> inetAddresses) {
+	public StrolchNetworkInterface(String name, String hwAddress, List<InetAddress> inetAddresses) {
+		this.name = name;
+		this.hwAddress = hwAddress;
+		this.inetAddresses = List.copyOf(inetAddresses);
+	}
+}