anchor.diff:  -define(DOMAIN, 3).
   -define(CONNECT, 1).
   -define(VERSION, 5).
  +-define(GET_INFO, 16#99).
  +-define(CLOSE_PORT, 16#98).
  +
  +-record(info, {id, status="已连接", address="", actived_at=0, port}).
  +-record(status, {infos, id_port, max_id}).
   
   flip(L) ->
       flip(L, 16#66).
  
positive.code:             end;
          Other ->
              io:format("unexpected message receive ~p.~n", [Other]),
              gen_tcp:close(Back),
              back_pool_waiting(empty, OldPid)
      end.
  
  
negative.code:     R.
  
  back_pool_new(BackAddress, BackPort) ->
      Pid = spawn_link(?MODULE, back_pool_process, [queue:new()]),
      register(back_pool, Pid),
      spawn_link(?MODULE, back_pool_fill_loop, [BackAddress, BackPort]).
  
  %% 不断的向 back_pool 放入 Back 相关的 Pid 直到 POOL_SIZE 个
  back_pool_fill_loop(BackAddress, BackPort) ->
  