feat(linux.net): DHCP server selection method

kura/org.eclipse.kura.linux.net/src/main/java/org/eclipse/kura/linux/net/dhcp/DhcpServerManager.java

@@ -1,12 +1,12 @@
 /*******************************************************************************
- * Copyright (c) 2011, 2023 Eurotech and/or its affiliates and others
- * 
+ * Copyright (c) 2011, 2024 Eurotech and/or its affiliates and others
+ *
  * This program and the accompanying materials are made
  * available under the terms of the Eclipse Public License 2.0
  * which is available at https://www.eclipse.org/legal/epl-2.0/
- * 
+ *
  * SPDX-License-Identifier: EPL-2.0
- * 
+ *
  * Contributors:
  *  Eurotech
  *******************************************************************************/
@@ -58,7 +58,8 @@ public DhcpServerManager(CommandExecutorService service) {
 
     public static DhcpServerTool getTool() {
         if (dhcpServerTool == DhcpServerTool.NONE) {
-            if (LinuxNetworkUtil.toolExists(DhcpServerTool.DNSMASQ.getValue())) {
+            if (LinuxNetworkUtil.toolExists(DhcpServerTool.DNSMASQ.getValue())
+                    && LinuxNetworkUtil.systemdSystemUnitExists(DhcpServerTool.DNSMASQ.getValue() + ".service")) {
                 dhcpServerTool = DhcpServerTool.DNSMASQ;
             } else if (LinuxNetworkUtil.toolExists(DhcpServerTool.UDHCPD.getValue())) {
                 dhcpServerTool = DhcpServerTool.UDHCPD;

kura/org.eclipse.kura.linux.net/src/main/java/org/eclipse/kura/linux/net/util/LinuxNetworkUtil.java

@@ -1,12 +1,12 @@
 /*******************************************************************************
- * Copyright (c) 2011, 2022 Eurotech and/or its affiliates and others
- * 
+ * Copyright (c) 2011, 2024 Eurotech and/or its affiliates and others
+ *
  * This program and the accompanying materials are made
  * available under the terms of the Eclipse Public License 2.0
  * which is available at https://www.eclipse.org/legal/epl-2.0/
- * 
+ *
  * SPDX-License-Identifier: EPL-2.0
- * 
+ *
  * Contributors:
  *  Eurotech
  *******************************************************************************/
@@ -17,6 +17,8 @@
 import java.io.File;
 import java.io.FileReader;
 import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
 import java.net.UnknownHostException;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -26,6 +28,13 @@
 import java.util.Optional;
 import java.util.Set;
 import java.util.StringTokenizer;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+import java.util.function.Consumer;
 
 import org.apache.commons.io.Charsets;
 import org.eclipse.kura.KuraErrorCode;
@@ -44,12 +53,9 @@
 
 public class LinuxNetworkUtil {
 
-    public static final String ACCESS_POINT_INTERFACE_SUFFIX = "_ap";
-
-    private static final String ETHTOOL_COMMAND = "ethtool";
-
     private static final Logger logger = LoggerFactory.getLogger(LinuxNetworkUtil.class);
 
+    public static final String ACCESS_POINT_INTERFACE_SUFFIX = "_ap";
     private static Map<String, LinuxIfconfig> ifconfigs = new HashMap<>();
     private static final String[] IGNORE_IFACES = { "can", "sit", "mon.wlan" };
     private static final ArrayList<String> TOOLS = new ArrayList<>();
@@ -65,13 +71,12 @@ public class LinuxNetworkUtil {
     private static final String IFCONFIG = "ifconfig";
     private static final String IWCONFIG = "iwconfig";
     private static final String IP = "ip";
-
     private static final String LINE_MSG = "line: {}";
-
     private static final String ERR_EXECUTING_CMD_MSG = "error executing command --- {} --- exit value={}";
-
     private static final String FAKE_MAC_ADDRESS = "12:34:56:78:ab:cd";
-
+    private static final String ETHTOOL_COMMAND = "ethtool";
+    private static final String[] DEFAULT_PATH = new String[] { "/sbin/", "/usr/sbin/", "/bin/", "/usr/bin/" };
+    private static final ProcessBuilder PROCESS_BUILDER = new ProcessBuilder();
     private final CommandExecutorService executorService;
     private final WifiOptions wifiOptions;
 
@@ -264,22 +269,66 @@ private boolean isWifiLinkUpInternal(String ifaceName) throws KuraException {
     }
 
     public static boolean toolExists(String tool) {
-        boolean ret = false;
-        final String[] searchFolders = new String[] { "/sbin/", "/usr/sbin/", "/bin/", "/usr/bin/" };
+        return getToolPath(tool).isPresent();
+    }
 
-        if (TOOLS.contains(tool)) {
-            ret = true;
+    public static Optional<String> getToolPath(String tool) {
+        Optional<String> optionalToolPath = getCachedTool(tool);
+        if (optionalToolPath.isPresent()) {
+            return optionalToolPath;
         } else {
-            for (String folder : searchFolders) {
-                File fTool = new File(folder + tool);
-                if (fTool.exists()) {
-                    TOOLS.add(tool);
-                    ret = true;
-                    break;
+            for (String folder : DEFAULT_PATH) {
+                String toolPath = folder + tool;
+                File toolFile = new File(toolPath);
+                if (toolFile.exists()) {
+                    TOOLS.add(toolPath);
+                    return Optional.of(toolPath);
                 }
             }
         }
-        return ret;
+        return Optional.empty();
+    }
+
+    private static Optional<String> getCachedTool(String tool) {
+        return TOOLS.stream().filter(item -> {
+            return item.endsWith(tool);
+        }).findFirst();
+    }
+
+    /**
+     * Checks if the given Systemd system unit is installed.
+     * The result is based on the exit code of "systemctl status <unitName>"
+     * as presented in https://www.man7.org/linux/man-pages/man1/systemctl.1.html#EXIT_STATUS
+     *
+     * @param unitName
+     *            the name of the Systemd system unit
+     * @return true if the unit is installed
+     */
+    public static boolean systemdSystemUnitExists(String unitName) {
+        Optional<String> optionalSystemctlPath = getToolPath("systemctl");
+        if (!optionalSystemctlPath.isPresent()) {
+            logger.debug("Systemctl command not found in default paths");
+            return false;
+        }
+        PROCESS_BUILDER.command(optionalSystemctlPath.get(), "status", unitName);
+        Process process;
+        try {
+            process = PROCESS_BUILDER.start();
+            StreamGobbler streamGobbler = new StreamGobbler(process.getInputStream(), logger::debug);
+            ExecutorService executor = Executors.newSingleThreadExecutor();
+            Future<?> future = executor.submit(streamGobbler);
+
+            int exitCode = process.waitFor();
+            future.get(10, TimeUnit.SECONDS);
+            return exitCode < 4;
+        } catch (IOException | ExecutionException | TimeoutException e) {
+            logger.error(String.format("Cannot check %s unit existence", unitName), e);
+            return false;
+        } catch (InterruptedException e1) {
+            Thread.currentThread().interrupt();
+            logger.error(String.format("Cannot check %s unit existence", unitName), e1);
+            return false;
+        }
     }
 
     /**
@@ -1124,7 +1173,7 @@ public void createApNetworkInterface(String ifaceName, String dedicatedApInterfa
             return;
         }
 
-        CommandStatus status = this.executeCommand(formIwDevIfaceInterfaceAddAp(ifaceName, dedicatedApInterface));
+        CommandStatus status = executeCommand(formIwDevIfaceInterfaceAddAp(ifaceName, dedicatedApInterface));
 
         if (!status.getExitStatus().isSuccessful()) {
             throw new KuraException(KuraErrorCode.OS_COMMAND_ERROR,
@@ -1137,7 +1186,7 @@ public void setNetworkInterfaceMacAddress(String ifaceName) throws KuraException
             return;
         }
 
-        CommandStatus status = this.executeCommand(formIpLinkSetAddress(ifaceName, FAKE_MAC_ADDRESS));
+        CommandStatus status = executeCommand(formIpLinkSetAddress(ifaceName, FAKE_MAC_ADDRESS));
 
         if (!status.getExitStatus().isSuccessful()) {
             throw new KuraException(KuraErrorCode.OS_COMMAND_ERROR,
@@ -1150,7 +1199,7 @@ public void setNetworkInterfaceLinkUp(String ifaceName) throws KuraException {
             return;
         }
 
-        CommandStatus status = this.executeCommand(formIpLinkSetStatus(ifaceName, "up"));
+        CommandStatus status = executeCommand(formIpLinkSetStatus(ifaceName, "up"));
 
         if (!status.getExitStatus().isSuccessful()) {
             throw new KuraException(KuraErrorCode.OS_COMMAND_ERROR, "Failed to set link up for interface " + ifaceName);
@@ -1162,7 +1211,7 @@ public void setNetworkInterfaceLinkDown(String ifaceName) throws KuraException {
             return;
         }
 
-        CommandStatus status = this.executeCommand(formIpLinkSetStatus(ifaceName, "down"));
+        CommandStatus status = executeCommand(formIpLinkSetStatus(ifaceName, "down"));
 
         if (!status.getExitStatus().isSuccessful()) {
             throw new KuraException(KuraErrorCode.OS_COMMAND_ERROR, "Failed to set link up for interface " + ifaceName);
@@ -1178,4 +1227,20 @@ private CommandStatus executeCommand(String[] commandString) {
         return this.executorService.execute(command);
     }
 
+    private static class StreamGobbler implements Runnable {
+
+        private final InputStream inputStream;
+        private final Consumer<String> consumer;
+
+        public StreamGobbler(InputStream inputStream, Consumer<String> consumer) {
+            this.inputStream = inputStream;
+            this.consumer = consumer;
+        }
+
+        @Override
+        public void run() {
+            new BufferedReader(new InputStreamReader(this.inputStream)).lines().forEach(this.consumer);
+        }
+    }
+
 }

kura/test/org.eclipse.kura.linux.net.test/src/test/java/org/eclipse/kura/linux/net/dhcp/DhcpServerManagerTest.java

@@ -1,12 +1,12 @@
 /*******************************************************************************
- * Copyright (c) 2017, 2023 Eurotech and/or its affiliates and others
- * 
+ * Copyright (c) 2017, 2024 Eurotech and/or its affiliates and others
+ *
  * This program and the accompanying materials are made
  * available under the terms of the Eclipse Public License 2.0
  * which is available at https://www.eclipse.org/legal/epl-2.0/
- * 
+ *
  * SPDX-License-Identifier: EPL-2.0
- * 
+ *
  * Contributors:
  *  Eurotech
  ******************************************************************************/
@@ -27,9 +27,12 @@
 import org.eclipse.kura.linux.net.dhcp.server.DnsmasqLeaseReader;
 import org.eclipse.kura.linux.net.dhcp.server.UdhcpdConfigConverter;
 import org.eclipse.kura.linux.net.dhcp.server.UdhcpdLeaseReader;
+import org.eclipse.kura.linux.net.util.LinuxNetworkUtil;
+import org.junit.After;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.TemporaryFolder;
+import org.mockito.MockedStatic;
 import org.mockito.Mockito;
 
 public class DhcpServerManagerTest {
@@ -50,6 +53,8 @@ public class DhcpServerManagerTest {
     private Optional<DhcpServerConfigConverter> returnedConfigConverter;
     private Optional<DhcpServerLeaseReader> returnedLeaseReader;
     private Exception occurredException;
+    private MockedStatic<LinuxNetworkUtil> mockedLinuxNetworkUtil;
+    private DhcpServerTool tool;
 
     /*
      * Scenarios
@@ -268,6 +273,63 @@ public void shouldReturnLeaseReaderForNone() throws NoSuchFieldException {
         thenReturnedLeaseReaderIsEmpty();
     }
 
+    @Test
+    public void shouldGetDnsmasqToolIfBinaryAndUnitArePresent() throws NoSuchFieldException {
+        givenLinuxNetworkUtil("dnsmasq", Optional.of("dnsmasq.service"));
+        givenDhcpServerManager(DhcpServerTool.NONE);
+
+        whenGetTool();
+
+        thenToolIs(DhcpServerTool.DNSMASQ);
+    }
+
+    @Test
+    public void shouldNotGetDnsmasqToolIfOnlyBinaryIsPresent() throws NoSuchFieldException {
+        givenLinuxNetworkUtil("dnsmasq", Optional.empty());
+        givenDhcpServerManager(DhcpServerTool.NONE);
+
+        whenGetTool();
+
+        thenToolIs(DhcpServerTool.NONE);
+    }
+
+    @Test
+    public void shouldGetDhcpdTool() throws NoSuchFieldException {
+        givenLinuxNetworkUtil("dhcpd", Optional.empty());
+        givenDhcpServerManager(DhcpServerTool.NONE);
+
+        whenGetTool();
+
+        thenToolIs(DhcpServerTool.DHCPD);
+    }
+
+    @Test
+    public void shouldGetUdhcpdTool() throws NoSuchFieldException {
+        givenLinuxNetworkUtil("udhcpd", Optional.empty());
+        givenDhcpServerManager(DhcpServerTool.NONE);
+
+        whenGetTool();
+
+        thenToolIs(DhcpServerTool.UDHCPD);
+    }
+
+    @Test
+    public void shouldNotGetAnyTool() throws NoSuchFieldException {
+        givenLinuxNetworkUtil("", Optional.empty());
+        givenDhcpServerManager(DhcpServerTool.NONE);
+
+        whenGetTool();
+
+        thenToolIs(DhcpServerTool.NONE);
+    }
+
+    @After
+    public void deregisterStaticMocks() {
+        if (this.mockedLinuxNetworkUtil != null) {
+            this.mockedLinuxNetworkUtil.close();
+        }
+    }
+
     /*
      * Steps
      */
@@ -281,7 +343,16 @@ private void givenDhcpServerManager(DhcpServerTool dhcpServerTool) throws NoSuch
 
         TestUtil.setFieldValue(new DhcpServerManager(null), "dhcpServerTool", dhcpServerTool);
 
-        this.dhcpServerManager = new DhcpServerManager(executorMock);
+        this.dhcpServerManager = new DhcpServerManager(this.executorMock);
+    }
+
+    private void givenLinuxNetworkUtil(String toolName, Optional<String> unitName) {
+        this.mockedLinuxNetworkUtil = Mockito.mockStatic(LinuxNetworkUtil.class);
+        this.mockedLinuxNetworkUtil.when(() -> LinuxNetworkUtil.toolExists(toolName)).thenReturn(true);
+        if (unitName.isPresent()) {
+            this.mockedLinuxNetworkUtil.when(() -> LinuxNetworkUtil.systemdSystemUnitExists(unitName.get()))
+                    .thenReturn(true);
+        }
     }
 
     /*
@@ -328,6 +399,14 @@ private void whenGetLeaseReader() {
         }
     }
 
+    private void whenGetTool() {
+        try {
+            this.tool = DhcpServerManager.getTool();
+        } catch (Exception e) {
+            this.occurredException = e;
+        }
+    }
+
     /*
      * Then
      */
@@ -364,4 +443,7 @@ private void thenReturnedLeaseReaderIs(Class<?> dhcpServerLeaseReader) {
         assertEquals(dhcpServerLeaseReader, this.returnedLeaseReader.get().getClass());
     }
 
+    private void thenToolIs(DhcpServerTool expectedTool) {
+        assertEquals(expectedTool, this.tool);
+    }
 }