LwIP development | socket | UDP

** Reference resources ：**https://blog.csdn.net/Chuangke_Andy/article/details/113116289

** significance ：** Improve each platform lwip TCP/UDP Programming compatibility , Portability

Environmental Science :
1.freertos
2. Turn on LWIP_SOCKET
3. Bgi, HC32F4A0( Compatible )

Code programming

#if LWIP_SOCKET 
 /******socket_udp_server.c******/
#include "lwip/opt.h"
#include <lwip/sockets.h>
#include "lwip/sys.h"
#include "lwip/api.h"
#include "string.h"

#define SERVER_PORT (6666UL)
#define BUFF_SIZE (1024UL)

static char ReadBuff[BUFF_SIZE];

void vUdpServerTask(void){
    
  int sockfd, n, i;
  struct sockaddr_in server_addr, client_addr;
  socklen_t	client_addr_len;
	
  // Create packet socket (UDP) 
  sockfd = socket(AF_INET, SOCK_DGRAM, 0);         
	
  // Fill in address information 
  server_addr.sin_family = AF_INET;
  server_addr.sin_port = htons(SERVER_PORT);
  server_addr.sin_addr.s_addr = htonl(INADDR_ANY); // In itself IP
	
  // binding socket
  bind(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr));
  client_addr_len = sizeof(client_addr);
	
  while(1){
    
	  
	// Waiting for the client to send data 
	n = recvfrom(sockfd,ReadBuff,BUFF_SIZE,0,(struct sockaddr *)&client_addr, &client_addr_len);
	// Write back to the client 
	write(sockfd,ReadBuff,n);
  }
	
}
#endif