STM32F4怎么用LWIP协议栈里面的TFTP协议上传文件

第一步：用tftpserver.c中的err_t tftp_send_message(struct udp_pcb *upcb, struct ip_addr *to_ip, int to_port, char *buf, int buflen)向指定地址发送写文件请求；

第二步：用tftpserver.c中的void process_tftp_request(struct pbuf *pkt_buf, struct ip_addr *addr, u16_t port)函数处理回应，如果接收到回应后，process_tftp_request函数中的int tftp_process_write(struct udp_pcb *upcb, struct ip_addr *to, int to_port, char *FileName)函数发送数据文件。

基本流程就是上述所说，但是tftp_send_message()函数中的参数struct udp_pcb *upcb，数据结构非常复杂

struct udp_pcb {

/* Common members of all PCB types */

IP_PCB;

/* Protocol specific PCB members */

struct udp_pcb *next;

u8_t flags;

/* ports are in host byte order */

u16_t local_port, remote_port;

#if LWIP_IGMP

/* outgoing network interface for multicast packets */

struct ip_addr multicast_ip;

#endif /* LWIP_IGMP */

#if LWIP_UDPLITE

/* used for UDP_LITE only */

u16_t chksum_len_rx, chksum_len_tx;

#endif /* LWIP_UDPLITE */

/* receive callback function

* addr and port are in same byte order as in the pcb

* The callback is responsible for freeing the pbuf

* if it's not used any more.

*

* ATTENTION: Be aware that 'addr' points into the pbuf 'p' so freeing this pbuf

* makes 'addr' invalid, too.

*

* @param arg user supplied argument (udp_pcb.recv_arg)

* @param pcb the udp_pcb which received data

* @param p the packet buffer that was received

* @param addr the remote IP address from which the packet was received

* @param port the remote port from which the packet was received

*/

void (* recv)(void *arg, struct udp_pcb *pcb, struct pbuf *p,

struct ip_addr *addr, u16_t port);

/* user-supplied argument for the recv callback */

void *recv_arg;

};