[Pan 3238] Fix rlpx startup (#114)

Signed-off-by: Meredith Baxter <meredith.baxter@consensys.net>

ethereum/p2p/src/main/java/org/hyperledger/besu/ethereum/p2p/rlpx/RlpxAgent.java

@@ -125,7 +125,19 @@ public class RlpxAgent {
     }
 
     setupListeners();
-    return connectionInitializer.start();
+    return connectionInitializer
+        .start()
+        .thenApply(
+            (socketAddress) -> {
+              LOG.info("P2P RLPx agent started and listening on {}.", socketAddress);
+              return socketAddress.getPort();
+            })
+        .whenComplete(
+            (res, err) -> {
+              if (err != null) {
+                LOG.error("Failed to start P2P RLPx agent.", err);
+              }
+            });
   }
 
   public CompletableFuture<Void> stop() {

ethereum/p2p/src/main/java/org/hyperledger/besu/ethereum/p2p/rlpx/connections/ConnectionInitializer.java

@@ -17,6 +17,7 @@ package org.hyperledger.besu.ethereum.p2p.rlpx.connections;
 import org.hyperledger.besu.ethereum.p2p.peers.Peer;
 import org.hyperledger.besu.ethereum.p2p.rlpx.ConnectCallback;
 
+import java.net.InetSocketAddress;
 import java.util.concurrent.CompletableFuture;
 
 public interface ConnectionInitializer {
@@ -25,9 +26,9 @@ public interface ConnectionInitializer {
    * Start the connection initializer. Begins listening for incoming connections. Start allowing
    * outbound connections.
    *
-   * @return The port on which we're listening for incoming connections.
+   * @return The address on which we're listening for incoming connections.
    */
-  CompletableFuture<Integer> start();
+  CompletableFuture<InetSocketAddress> start();
 
   /**
    * Shutdown the connection initializer. Stop listening for incoming connections and stop

ethereum/p2p/src/main/java/org/hyperledger/besu/ethereum/p2p/rlpx/connections/netty/NettyConnectionInitializer.java

@@ -14,8 +14,6 @@
  */
 package org.hyperledger.besu.ethereum.p2p.rlpx.connections.netty;
 
-import static com.google.common.base.Preconditions.checkState;
-
 import org.hyperledger.besu.crypto.SECP256K1.KeyPair;
 import org.hyperledger.besu.ethereum.p2p.config.RlpxConfiguration;
 import org.hyperledger.besu.ethereum.p2p.discovery.DiscoveryPeer;
@@ -48,12 +46,9 @@ import io.netty.channel.socket.SocketChannel;
 import io.netty.channel.socket.nio.NioServerSocketChannel;
 import io.netty.channel.socket.nio.NioSocketChannel;
 import io.netty.util.concurrent.SingleThreadEventExecutor;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
 
 public class NettyConnectionInitializer implements ConnectionInitializer {
 
-  private static final Logger LOG = LogManager.getLogger();
   private static final int TIMEOUT_SECONDS = 10;
 
   private final KeyPair keyPair;
@@ -95,8 +90,8 @@ public class NettyConnectionInitializer implements ConnectionInitializer {
   }
 
   @Override
-  public CompletableFuture<Integer> start() {
-    final CompletableFuture<Integer> listeningPortFuture = new CompletableFuture<>();
+  public CompletableFuture<InetSocketAddress> start() {
+    final CompletableFuture<InetSocketAddress> listeningPortFuture = new CompletableFuture<>();
     if (!started.compareAndSet(false, true)) {
       listeningPortFuture.completeExceptionally(
           new IllegalStateException(
@@ -114,19 +109,17 @@ public class NettyConnectionInitializer implements ConnectionInitializer {
         future -> {
           final InetSocketAddress socketAddress =
               (InetSocketAddress) server.channel().localAddress();
+          if (!future.isSuccess() || socketAddress == null) {
             final String message =
                 String.format(
-                  "Unable start up P2P network on %s:%s.  Check for port conflicts.",
+                    "Unable start listening on %s:%s. Check for port conflicts.",
                     config.getBindHost(), config.getBindPort());
-
-          if (!future.isSuccess()) {
-            LOG.error(message, future.cause());
+            listeningPortFuture.completeExceptionally(
+                new IllegalStateException(message, future.cause()));
+            return;
           }
-          checkState(socketAddress != null, message);
 
-          LOG.info("P2P network started and listening on {}", socketAddress);
-          final int listeningPort = socketAddress.getPort();
-          listeningPortFuture.complete(listeningPort);
+          listeningPortFuture.complete(socketAddress);
         });
 
     return listeningPortFuture;

ethereum/p2p/src/test/java/org/hyperledger/besu/ethereum/p2p/rlpx/connections/MockConnectionInitializer.java

@@ -18,6 +18,7 @@ import org.hyperledger.besu.ethereum.p2p.peers.Peer;
 import org.hyperledger.besu.ethereum.p2p.rlpx.ConnectCallback;
 import org.hyperledger.besu.util.Subscribers;
 
+import java.net.InetSocketAddress;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -52,8 +53,10 @@ public class MockConnectionInitializer implements ConnectionInitializer {
   }
 
   @Override
-  public CompletableFuture<Integer> start() {
-    return CompletableFuture.completedFuture(NEXT_PORT.incrementAndGet());
+  public CompletableFuture<InetSocketAddress> start() {
+    InetSocketAddress socketAddress =
+        new InetSocketAddress("127.0.0.1", NEXT_PORT.incrementAndGet());
+    return CompletableFuture.completedFuture(socketAddress);
   }
 
   @Override