Fix Websocket ping after close. Fix Websocket unhandled exception.

Fix for quarkusio#99 where a Websocket ping was responded after session was marked closed and other messages were dropped.

Fix for unhandled exceptions in Websocket channel pipeline. FrameHandler catches them
and passes to onError instead of ignoring and running in default logger / stack trace printing by DefaultChannelPipeline.TailContext.

websocket/core/src/main/java/io/undertow/websockets/FrameHandler.java

@@ -51,6 +51,7 @@
 import io.netty.handler.codec.http.websocketx.PongWebSocketFrame;
 import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
 import io.netty.handler.codec.http.websocketx.WebSocketFrame;
+import io.netty.util.ReferenceCountUtil;
 import io.undertow.websockets.util.ClassUtils;
 
 /**
@@ -130,15 +131,27 @@ protected void channelRead0(ChannelHandlerContext ctx, WebSocketFrame msg) throw
         processFrame(msg);
     }
 
+    /**
+     * Catch unhandled channel pipeline exceptions and avoid default handler with stack trace print.
+     * Pass to OnError to enable implementation to handle that exception.
+     * This might occur for example on unexpected client connection close.
+     */
+    @Override
+    public void exceptionCaught(final ChannelHandlerContext ctx, final Throwable cause) {
+        try {
+            invokeOnError(cause);
+        } finally {
+            ReferenceCountUtil.release(cause);
+        }
+    }
+
     private void processFrame(WebSocketFrame msg) throws IOException {
         if (msg instanceof CloseWebSocketFrame) {
             onCloseFrame((CloseWebSocketFrame) msg);
         } else if (msg instanceof PongWebSocketFrame) {
             onPongMessage((PongWebSocketFrame) msg);
         } else if (msg instanceof PingWebSocketFrame) {
-            byte[] data = new byte[msg.content().readableBytes()];
-            msg.content().readBytes(data);
-            session.getAsyncRemote().sendPong(ByteBuffer.wrap(data));
+            onPingFrame(msg);
         } else if (msg instanceof TextWebSocketFrame) {
             onText(msg, ((TextWebSocketFrame) msg).text());
         } else if (msg instanceof BinaryWebSocketFrame) {
@@ -152,6 +165,18 @@ private void processFrame(WebSocketFrame msg) throws IOException {
         }
     }
 
+    void onPingFrame(final WebSocketFrame message) throws IOException {
+        if (session.isSessionClosed()) {
+            //to bad, the channel has already been closed
+            //we just ignore messages that are received after we have closed, as the endpoint is no longer in a valid state to deal with them
+            //this this should only happen if a message was on the wire when we called close()
+            return;
+        }
+        byte[] data = new byte[message.content().readableBytes()];
+        message.content().readBytes(data);
+        session.getAsyncRemote().sendPong(ByteBuffer.wrap(data));
+    }
+
     void onCloseFrame(final CloseWebSocketFrame message) {
         if (session.isSessionClosed()) {
             //we have already handled this when we sent the close frame