Add port conflict exception

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

@@ -219,6 +219,8 @@ public CompletableFuture<?> start() {
 
     final CompletableFuture<?> resultFuture = new CompletableFuture<>();
     try {
+      NetworkUtility.checkPortsAvailable(config.getPort());
+
       // Create the HTTP server and a router object.
       httpServer = vertx.createHttpServer(getHttpServerOptions());
 

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

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

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

@@ -23,6 +23,7 @@
 import org.hyperledger.besu.ethereum.api.jsonrpc.websocket.subscription.SubscriptionManager;
 import org.hyperledger.besu.metrics.BesuMetricCategory;
 import org.hyperledger.besu.plugin.services.MetricsSystem;
+import org.hyperledger.besu.util.NetworkUtility;
 
 import java.net.InetSocketAddress;
 import java.util.Optional;
@@ -104,7 +105,7 @@ public CompletableFuture<?> start() {
         "Starting Websocket service on {}:{}", configuration.getHost(), configuration.getPort());
 
     final CompletableFuture<?> resultFuture = new CompletableFuture<>();
-
+    NetworkUtility.checkPortsAvailable(configuration.getPort());
     httpServer =
         vertx
             .createHttpServer(

ethereum/api/src/test/java/org/hyperledger/besu/ethereum/api/jsonrpc/JsonRpcHttpServiceTest.java

@@ -15,6 +15,7 @@
 package org.hyperledger.besu.ethereum.api.jsonrpc;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.doReturn;
@@ -2083,4 +2084,19 @@ public void handleResponseWithOptionalExistingValue() throws Exception {
       rpcMethods.remove(method.getName());
     }
   }
+
+  @Test
+  public void failWhenPortIsAlreadyInUse() throws Exception {
+    final JsonRpcConfiguration config = createJsonRpcConfig();
+    config.setHost("0.0.0.0");
+    config.setPort(8545);
+    final JsonRpcHttpService firstServiceToAllocatePort = createJsonRpcHttpService(config);
+    final JsonRpcHttpService secondServiceToAllocatePort = createJsonRpcHttpService(config);
+    firstServiceToAllocatePort.start().join();
+
+    assertThatIllegalArgumentException()
+        .isThrownBy(() -> secondServiceToAllocatePort.start())
+        .withMessageContaining(
+            "Port 8545 is already in use. Check for other processes using this port.");
+  }
 }

ethereum/api/src/test/java/org/hyperledger/besu/ethereum/api/jsonrpc/websocket/WebSocketServiceTest.java

@@ -15,6 +15,7 @@
 package org.hyperledger.besu.ethereum.api.jsonrpc.websocket;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.reset;
 import static org.mockito.Mockito.spy;
@@ -385,4 +386,25 @@ public void handleResponseWithOptionalExistingValue(final TestContext context) {
     async.awaitSuccess(VERTX_AWAIT_TIMEOUT_MILLIS);
     async.handler((result) -> websocketMethods.remove(method.getName()));
   }
+
+  @Test
+  public void failWhenPortIsAlreadyInUse() {
+    websocketConfiguration = WebSocketConfiguration.createDefault();
+    websocketConfiguration.setHost("0.0.0.0");
+    websocketConfiguration.setPort(8546);
+    final WebSocketService firstWebSocketService =
+        new WebSocketService(
+            vertx, websocketConfiguration, webSocketMessageHandlerSpy, new NoOpMetricsSystem());
+
+    firstWebSocketService.start().join();
+
+    final WebSocketService secondWebSocketService =
+        new WebSocketService(
+            vertx, websocketConfiguration, webSocketMessageHandlerSpy, new NoOpMetricsSystem());
+
+    assertThatIllegalArgumentException()
+        .isThrownBy(() -> secondWebSocketService.start())
+        .withMessageContaining(
+            "Port 8546 is already in use. Check for other processes using this port.");
+  }
 }

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

@@ -14,20 +14,26 @@
  */
 package org.hyperledger.besu.util;
 
+import java.io.IOException;
 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 +104,23 @@ 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 void checkPortsAvailable(final int tcpPort) {
+    if (!isPortAvailableForTcp(tcpPort)) {
+      throw new InvalidConfigurationException(
+          String.format(
+              "Port %d is already in use. Check for other processes using this port.", tcpPort));
+    }
+  }
 }