NPE when Future.cancel happens before channel is attached, close AsyncHttpClient#762

Author: Stephane Landelle

src/main/java/com/ning/http/client/providers/netty/future/NettyResponseFuture.java

@@ -129,8 +129,11 @@ public boolean cancel(boolean force) {
         if (isCancelled.getAndSet(true))
             return false;
 
-        Channels.setDiscard(channel);
-        Channels.silentlyCloseChannel(channel);
+        // cancel could happen before channel was attached
+        if (channel != null) {
+            Channels.setDiscard(channel);
+            Channels.silentlyCloseChannel(channel);
+        }
 
         if (!onThrowableCalled.getAndSet(true)) {
             try {
@@ -371,6 +374,12 @@ public void setConnectAllowed(boolean allowConnect) {
     }
 
     public void attachChannel(Channel channel, boolean reuseChannel) {
+
+        // future could have been cancelled first
+        if (isDone()) {
+            Channels.silentlyCloseChannel(channel);
+        }
+
         this.channel = channel;
         this.reuseChannel = reuseChannel;
     }