LINUX C UDP协议

简介

UDP协议是面向无连接的协议，一般用于一些实时性比较强的或正确率要求不高的通信中。

流程

上一节当中讲了linux下socket TCP编程，有了TCP的基础，UDP就好理解多了。

接收端

1. 创建socket
2. 绑定ip和端口

3. 等待接收
   使用recvfrom函数

   /* Read N bytes into BUF through socket FD.   If ADDR is not NULL, fill in *ADDR_LEN bytes of it with tha address of   the sender, and store the actual size of the address in *ADDR_LEN.   Returns the number of bytes read or -1 for errors.   This function is a cancellation point and therefore not marked with   __THROW.  */extern ssize_t recvfrom (int __fd, void * __buf, size_t __n,             int __flags, __SOCKADDR_ARG __addr,             socklen_t * __addr_len);

4. close(fd) 关闭SOCKET

　发送端

1. 创建socket

2. 发送
   使用sendto()函数

   /* Send N bytes of BUF on socket FD to peer at address ADDR (which is   ADDR_LEN bytes long).  Returns the number sent, or -1 for errors.   This function is a cancellation point and therefore not marked with   __THROW.  */extern ssize_t sendto (int __fd, const void *__buf, size_t __n,               int __flags, __CONST_SOCKADDR_ARG __addr,               socklen_t __addr_len);

3. close(fd) 关闭SOCKET