Created attachment 37583 [details]
patch for WsWebSocketContainer.java 8.5.37 fd leaks

An attempt to create a new websocket connection with WebSocketContainer.connectToServer to an unresolvable host raises java.nio.channels.UnresolvedAddressException, but leaves some socket resources allocated. This can be verified by putting the above connect method in a loop and monitoring the open files of the java process.
On linux this can be done with e.g. lsof: the number of socket fd increase on every iteration up to the OS limit, then "Too many open files" IOExceptions are raised.

Browsing the org.apache.tomcat.websocket.WsWebSocketContainer.connectToServerRecursive() code
I found that the call

        // Open the connection
        Future<Void> fConnect = socketChannel.connect(sa);

raises the UnresolvedAddressException, leaving the socketChannel object opened.

I think the same problem could arise with a proxy server that return a status code != 200, handled in lines 313-317.

I tried to solve extending the try block to include the above call, changing the corresponding finally block to cover extra cases.