TCP数据包的填充并发送，考虑到课设并没有严格要求我们成功发送到目的地，所以利用函数sendto（）来实现数据包的发送，这种方式不可靠，只能保证数据是否从源地发送出去，至于有没有到达目的地就不管了。-TCP packet and send the filled, taking into account the lessons did not set strict demands of our success is sent to the destination, so the use of function sendto () to achieve the data packet to send, this method is unreliable and can only guarantee that the data from source sent out, as have not reach their destinations on and go on.