3.TCP回响服务器实现及源码分析上

1.tcp_echoserver.c 移植

文件目录

C:\Users\Think\STM32Cube\Repository\STM32Cube_FW_F4_V1.24.1\Projects\STM324xG_EVAL\Applications\LwIP\LwIP_TCP_Echo_Server\Src

地址是本机的，端口号是7

2.实验分析

1.移植tcp_echoserver.c文件

2.main.c添加tcp_echoserver_init

3.编译烧写

4.使用NC命令进行连接

5.发送任意数据等待回响

3.tcp_echoserver 业务分析

static struct tcp_pcb *tcp_echoserver_pcb;

/* ECHO protocol states */
enum tcp_echoserver_states
{
  ES_NONE = 0,
  ES_ACCEPTED,
  ES_RECEIVED,
  ES_CLOSING
};

/* structure for maintaing connection infos to be passed as argument 
   to LwIP callbacks*/
struct tcp_echoserver_struct
{
  u8_t state;             /* current connection state */
  u8_t retries;
  struct tcp_pcb *pcb;    /* pointer on the current tcp_pcb */
  struct pbuf *p;         /* pointer on the received/to be transmitted pbuf */
};

void tcp_echoserver_init(void);
static err_t tcp_echoserver_accept(void *arg, struct tcp_pcb *newpcb, err_t err);
static err_t tcp_echoserver_recv(void *arg, struct tcp_pcb *tpcb, struct pbuf *p, err_t err);
static void tcp_echoserver_error(void *arg, err_t err);
static err_t tcp_echoserver_poll(void *arg, struct tcp_pcb *tpcb);
static err_t tcp_echoserver_sent(void *arg, struct tcp_pcb *tpcb, u16_t len);
static void tcp_echoserver_send(struct tcp_pcb *tpcb, struct tcp_echoserver_struct *es);
static void tcp_echoserver_connection_close(struct tcp_pcb *tpcb, struct tcp_echoserver_struct *es);