close ServerSocket after testing availablity

Signed-off-by: stefan.pingel@consensys.net <stefan.pingel@consensys.net>

besu/src/main/java/org/hyperledger/besu/cli/BesuCommand.java

@@ -2555,11 +2555,12 @@ public class BesuCommand implements DefaultCommandValues, Runnable {
         .forEach(
             port -> {
               if (port.equals(p2PDiscoveryOptionGroup.p2pPort)
-                  && !NetworkUtility.isPortAvailable(port)) {
+                  && (NetworkUtility.isPortUnavailableForTcp(port)
+                      || NetworkUtility.isPortUnavailableForUdp(port))) {
                 unavailablePorts.add(port);
               }
               if (!port.equals(p2PDiscoveryOptionGroup.p2pPort)
-                  && !NetworkUtility.isPortAvailableForTcp(port)) {
+                  && NetworkUtility.isPortUnavailableForTcp(port)) {
                 unavailablePorts.add(port);
               }
             });

util/src/main/java/org/hyperledger/besu/util/NetworkUtility.java

@@ -160,41 +160,39 @@ public class NetworkUtility {
   }
 
   /**
-   * Is port available for tcp.
+   * Is this port unavailable for tcp.
    *
    * @param port the port
-   * @return the boolean
+   * @return true if the port is unavailable for tcp
    */
-  public static boolean isPortAvailableForTcp(final int port) {
+  public static boolean isPortUnavailableForTcp(final int port) {
     try (final ServerSocket serverSocket = new ServerSocket()) {
       serverSocket.setReuseAddress(true);
       serverSocket.bind(new InetSocketAddress(port));
-      return true;
+      serverSocket.close();
+      return false;
     } catch (IOException ex) {
       LOG.trace(String.format("Failed to open port %d for TCP", port), ex);
     }
-    return false;
+    return true;
   }
 
-  private static boolean isPortAvailableForUdp(final int port) {
+  /**
+   * Is this port unavailable for udp.
+   *
+   * @param port the port
+   * @return true if the port is unavailable for udp
+   */
+  public static boolean isPortUnavailableForUdp(final int port) {
     try (final DatagramSocket datagramSocket = new DatagramSocket(null)) {
       datagramSocket.setReuseAddress(true);
       datagramSocket.bind(new InetSocketAddress(port));
-      return true;
+      datagramSocket.close();
+      return false;
     } catch (IOException ex) {
       LOG.trace(String.format("failed to open port %d for UDP", port), ex);
     }
-    return false;
+    return true;
-  }
-
-  /**
-   * Is port available.
-   *
-   * @param port the port
-   * @return the boolean
-   */
-  public static boolean isPortAvailable(final int port) {
-    return isPortAvailableForTcp(port) && isPortAvailableForUdp(port);
   }
 
   /**

util/src/test/java/org/hyperledger/besu/util/NetworkUtilityTest.java

@@ -17,6 +17,7 @@ package org.hyperledger.besu.util;
 import static org.assertj.core.api.Assertions.assertThat;
 
 import java.io.IOException;
+import java.net.DatagramSocket;
 import java.net.InetSocketAddress;
 import java.net.ServerSocket;
 
@@ -35,12 +36,19 @@ public class NetworkUtilityTest {
   }
 
   @Test
-  public void assertPortIsNotAvailable() throws IOException {
+  public void assertTcpPortIsNotAvailable() throws IOException {
     final ServerSocket serverSocket = new ServerSocket(8541);
-    assertThat(!NetworkUtility.isPortAvailable(8541)).isEqualTo(true);
+    assertThat(NetworkUtility.isPortUnavailableForTcp(8541)).isEqualTo(true);
     serverSocket.close();
   }
 
+  @Test
+  public void assertUdpPortIsNotAvailable() throws IOException {
+    final DatagramSocket datagramSocket = new DatagramSocket(8541);
+    assertThat(NetworkUtility.isPortUnavailableForUdp(8541)).isEqualTo(true);
+    datagramSocket.close();
+  }
+
   @Test
   public void assertLocalhostIdentification() {
     assertThat(NetworkUtility.isLocalhostAddress("127.0.0.1")).isTrue();