socket.setBroadcast(flag)
flag<boolean>
设置或清除 SO_BROADCAST 套接字选项。
当设置为 true 时,UDP 数据包可能会被发送到本地接口的广播地址。
如果在未绑定的套接字上调用此方法将抛出 EBADF。
flag<boolean>
Sets or clears the SO_BROADCAST socket option. When set to true, UDP
packets may be sent to a local interface's broadcast address.
This method throws EBADF if called on an unbound socket.