Add port conflict exception

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

@@ -180,6 +180,7 @@
 import org.hyperledger.besu.services.SecurityModuleServiceImpl;
 import org.hyperledger.besu.services.StorageServiceImpl;
 import org.hyperledger.besu.services.kvstore.InMemoryStoragePlugin;
+import org.hyperledger.besu.util.InvalidConfigurationException;
 import org.hyperledger.besu.util.Log4j2ConfiguratorUtil;
 import org.hyperledger.besu.util.NetworkUtility;
 import org.hyperledger.besu.util.PermissioningConfigurationValidator;
@@ -1972,7 +1973,7 @@ private void issueOptionWarnings() {
 
   private void configure() throws Exception {
     checkPortClash();
-
+    checkIfRequiredPortsAreAvailable();
     syncMode = getDefaultSyncModeIfNotSet(syncMode);
 
     ethNetworkConfig = updateNetworkConfig(network);
@@ -3126,6 +3127,25 @@ private void checkPortClash() {
             });
   }
 
+  private void checkIfRequiredPortsAreAvailable() {
+    List<Integer> unavailablePorts = new ArrayList<>();
+    getEffectivePorts().stream()
+        .filter(Objects::nonNull)
+        .filter(port -> port > 0)
+        .forEach(
+            port -> {
+              if (!NetworkUtility.isPortAvailable(port)) {
+                unavailablePorts.add(port);
+              }
+            });
+    if (!unavailablePorts.isEmpty()) {
+      throw new InvalidConfigurationException(
+          "Port(s) '"
+              + unavailablePorts.toString()
+              + "' already in use. Check for other processes using the port(s).");
+    }
+  }
+
   /**
    * * Gets the list of effective ports (ports that are enabled).
    *

besu/src/test/java/org/hyperledger/besu/cli/BesuCommandTest.java

@@ -100,6 +100,7 @@
 import java.io.File;
 import java.io.IOException;
 import java.math.BigInteger;
+import java.net.ServerSocket;
 import java.net.URI;
 import java.net.URL;
 import java.nio.file.Files;
@@ -5371,4 +5372,17 @@ public void posBlockCreationMaxTimeOutOfAllowedRange() {
     assertThat(commandErrorOutput.toString(UTF_8))
         .contains("--Xpos-block-creation-max-time must be positive and ≤ 12000");
   }
+
+  @Test
+  public void portInUseReportsError() throws IOException {
+    final ServerSocket serverSocket = new ServerSocket(8545);
+
+    parseCommand("--rpc-http-enabled");
+
+    assertThat(commandOutput.toString(UTF_8)).isEmpty();
+    assertThat(commandErrorOutput.toString(UTF_8))
+        .contains("Port(s) '[8545]' already in use. Check for other processes using the port(s).");
+
+    serverSocket.close();
+  }
 }

ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/jsonrpc/JsonRpcHttpService.java

@@ -219,6 +219,7 @@ public CompletableFuture<?> start() {
 
     final CompletableFuture<?> resultFuture = new CompletableFuture<>();
     try {
+
       // Create the HTTP server and a router object.
       httpServer = vertx.createHttpServer(getHttpServerOptions());
 

ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/jsonrpc/websocket/WebSocketService.java

@@ -104,7 +104,6 @@ public CompletableFuture<?> start() {
         "Starting Websocket service on {}:{}", configuration.getHost(), configuration.getPort());
 
     final CompletableFuture<?> resultFuture = new CompletableFuture<>();
-
     httpServer =
         vertx
             .createHttpServer(

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

@@ -14,20 +14,27 @@
  */
 package org.hyperledger.besu.util;
 
+import java.io.IOException;
+import java.net.DatagramSocket;
 import java.net.Inet6Address;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.NetworkInterface;
+import java.net.ServerSocket;
 import java.net.SocketException;
 import java.net.UnknownHostException;
 import java.util.function.Supplier;
 
 import com.google.common.base.Suppliers;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 public class NetworkUtility {
   public static final String INADDR_ANY = "0.0.0.0";
   public static final String INADDR6_ANY = "0:0:0:0:0:0:0:0";
 
+  private static final Logger LOG = LoggerFactory.getLogger(NetworkUtility.class);
+
   private NetworkUtility() {}
 
   private static final Supplier<Boolean> ipv6Available =
@@ -98,4 +105,31 @@ public static void checkPort(final int port, final String portTypeName) {
               "%s port requires a value between 1 and 65535. Got %d.", portTypeName, port));
     }
   }
+
+  public static boolean isPortAvailableForTcp(final int port) {
+    try (final ServerSocket serverSocket = new ServerSocket()) {
+      serverSocket.setReuseAddress(true);
+      serverSocket.bind(new InetSocketAddress(port));
+      return true;
+    } catch (IOException ex) {
+      LOG.trace(String.format("Failed to open port %d for TCP", port), ex);
+    }
+    return false;
+  }
+
+  public static boolean isPortAvailableForUdp(final int port) {
+    try (final DatagramSocket datagramSocket = new DatagramSocket(null)) {
+      datagramSocket.setReuseAddress(true);
+      datagramSocket.bind(new InetSocketAddress(port));
+      return true;
+    } catch (IOException ex) {
+      LOG.trace(String.format("failed to open port %d for UDP", port), ex);
+    }
+    return false;
+  }
+
+  public static boolean isPortAvailable(final int port) {
+    if (isPortAvailableForTcp(port) && isPortAvailableForUdp(port)) return true;
+    return false;
+  }
 }