Check if the connectFuture has completed successfully properly. (#293)

Avoids throwing java.util.concurrent.ExecutionException when handling other framing errors in DeFramer.

ethereum/p2p/src/main/java/tech/pegasys/pantheon/ethereum/p2p/netty/DeFramer.java

@@ -125,7 +125,7 @@ final class DeFramer extends ByteToMessageDecoder {
             : throwable;
     if (cause instanceof FramingException) {
       LOG.debug("Invalid incoming message", throwable);
-      if (connectFuture.isDone()) {
+      if (connectFuture.isDone() && !connectFuture.isCompletedExceptionally()) {
         connectFuture.get().disconnect(DisconnectReason.BREACH_OF_PROTOCOL);
         return;
       }
@@ -135,7 +135,7 @@ final class DeFramer extends ByteToMessageDecoder {
     } else {
       LOG.error("Exception while processing incoming message", throwable);
     }
-    if (connectFuture.isDone()) {
+    if (connectFuture.isDone() && !connectFuture.isCompletedExceptionally()) {
       connectFuture.get().terminateConnection(DisconnectReason.TCP_SUBSYSTEM_ERROR, false);
     } else {
       connectFuture.completeExceptionally(throwable);

ethereum/p2p/src/test/java/tech/pegasys/pantheon/ethereum/p2p/netty/DeFramerTest.java

@@ -52,4 +52,22 @@ public class DeFramerTest {
 
     verify(peerConnection).disconnect(DisconnectReason.BREACH_OF_PROTOCOL);
   }
+
+  @Test
+  public void shouldHandleFramingExceptionWhenFutureCompletedExceptionally() throws Exception {
+    connectFuture.completeExceptionally(new Exception());
+
+    deFramer.exceptionCaught(ctx, new DecoderException(new FramingException("Test")));
+
+    verify(ctx).close();
+  }
+
+  @Test
+  public void shouldHandleGenericExceptionWhenFutureCompletedExceptionally() throws Exception {
+    connectFuture.completeExceptionally(new Exception());
+
+    deFramer.exceptionCaught(ctx, new DecoderException(new RuntimeException("Test")));
+
+    verify(ctx).close();
+  }
 }