使用C语言编写的局域网文件传输程序，基于UDP实现了自己的应用层协议，使用多线程，文件传输速度很快，自带拥塞控制，模拟了TCP的选择重传机制-Using the C language of the LAN file transfer program, based on UDP to achieve its own application layer protocol, using multi-threaded, file transfer is fast, bring their own con