Avoid SSL deadlock

This patch works around deadlocks that occur when sending data
bidirectionally using Erlang SSL sockets. It is possible that both sides
send enough data to fill up the buffers and block, without either side
being able to read data to empty the other side's buffer.  This is
typically avoided by having different processes handle the reading and
writing duties. But the Erlang SSL library uses a single gen_fsm for
both.

lib/ssl/src/tls_connection.erl

@@ -2355,9 +2355,21 @@ write_application_data(Data0, From, #state{socket = Socket,
 				    renegotiation = {true, internal}});
 	false ->
 	    {Msgs, ConnectionStates} = ssl_record:encode_data(Data, Version, ConnectionStates0),
-	    Result = Transport:send(Socket, Msgs),
-	    {reply, Result,
-	     connection, State#state{connection_states = ConnectionStates}, get_timeout(State)}
+        Active = case erlang:port_info(Socket, queue_size) of
+                     Size when Size > 8192 ->
+                         {ok, [{active, A}]} = inet:getopts(Socket, [active]),
+                         inet:setopts(Socket, [{active,true}]),
+                         A;
+                     _ ->
+                         undefined
+                 end,
+        Result = Transport:send(Socket, Msgs),
+        case Active of
+            undefined -> ok;
+            _ -> inet:setopts(Socket, [{active,Active}])
+        end,
+        {reply, Result,
+         connection, State#state{connection_states = ConnectionStates}, get_timeout(State)}
     end.
 
 time_to_renegotiate(_Data, #connection_states{current_write =