嵌入式学习L6网络编程D5UDP编程

网络编程

UDPclient端

/*udp demo */
/* usage:
 * ./client serv_ip serv_port 
*/
#include "net.h"
void usage(char *s)
{
	printf("\nThis is udp demo!\n");
	printf("\nUsage:\n\t %s serv_ip serv_port",s);
	printf("\n\t serv_ip: udp server ip address");
	printf("\n\t serv_port: udp server port(serv_port > 5000)\n\n");
}

int main(int argc, char *argv[])
{
	int fd = -1;
	int port = SERV_PORT;
	
	port = atoi(argv[2]);
	if(port < 0 || (port >0 && port <= 5000)) {
		usage(argv[0]);
		exit(1);
	}
        struct sockaddr_in sin;
	if(argc !=3) {
		usage(argv[0]);
		exit(1);
	}        

	/* 1. 创建socket fd*/
        if( (fd = socket(AF_INET,SOCK_DGRAM, 0)) < 0) { //UDP编程
                perror("socket");
                exit(1);
        }

	/*2.1 填充struct sockaddr_in结构体变量 */
        bzero(&sin,sizeof(sin));

        sin.sin_family = AF_INET;
        sin.sin_port = htons(SERV_PORT); //网络字节序的端口号
#if 0
        sin.sin_addr.s_addr = inet_addr(argv[1]);
#else
        if( inet_pton(AF_INET, argv[1], (void *)&sin.sin_addr) != 1) {
                perror("inet_pton");
                exit(1);
        }
#endif	
	printf("UDP client started!\n");
	char buf[BUFSIZ];
	while(1) {
		fprintf(stderr,"pls input string:");
		bzero(buf, BUFSIZ);
		if( fgets(buf, BUFSIZ-1, stdin) ==NULL) {
			perror("fgets");
			continue;
		}
		
		sendto(fd, buf, strlen(buf), 0, (struct sockaddr *)&sin, sizeof(sin)); 
		
		if( !strncasecmp(buf, QUIT_STR, strlen(QUIT_STR))) {  //用户输入了quit字符
                        printf("Client is exited!\n");
                        break;
                }
	
	}
	close(fd);
	return 0;
}

主要步骤：

serve

#include "net.h"

int main(void)
{

	int fd = -1;
 	struct sockaddr_in sin;
        
	/* 1. 创建socket fd */
        if ((fd = socket (AF_INET, SOCK_DGRAM, 0)) < 0) { //udp程序
                perror ("socket");
                exit (1);
        }

	/* 2. 允许绑定地址快速重用 */
        int b_reuse = 1;
        setsockopt (fd, SOL_SOCKET, SO_REUSEADDR, &b_reuse, sizeof (int));

	        /*2. 绑定 */
        /*2.1 填充struct sockaddr_in结构体变量 */
        bzero (&sin, sizeof (sin));
        sin.sin_family = AF_INET;
        sin.sin_port = htons (SERV_PORT);       //网络字节序的端口号

        /* 让服务器程序能绑定在任意的IP上 */
#if 1
        sin.sin_addr.s_addr = htonl (INADDR_ANY);
#else
        if (inet_pton (AF_INET, SERV_IP_ADDR, (void *) &sin.sin_addr) != 1) {
                perror ("inet_pton");
                exit (1);
        }
#endif
        /*2.2 绑定 */
        if (bind (fd, (struct sockaddr *) &sin, sizeof (sin)) < 0) {
                perror ("bind");
                exit (1);
        }
	
	char buf[BUFSIZ];
	struct sockaddr_in cin;
	socklen_t addrlen = sizeof(cin);
	printf("\nUDP server started!\n");
	while(1) {
		bzero(buf, BUFSIZ);
		if( recvfrom(fd, buf, BUFSIZ-1, 0,(struct sockaddr *)&cin, &addrlen ) < 0) {
			perror("recvfrom");
			continue;
		}
		
		 char ipv4_addr[16];
                if (!inet_ntop (AF_INET, (void *) &cin.sin_addr, ipv4_addr, sizeof (cin))) {
                                perror ("inet_ntop");
                                exit (1);
 	        }

		printf("Recived from(%s:%d), data:%s",ipv4_addr, ntohs(cin.sin_port), buf);
		
		if (!strncasecmp (buf, QUIT_STR, strlen (QUIT_STR))) {  //用户输入了quit字符
                       printf ("Client(%s:%d) is exiting!\n", ipv4_addr, ntohs(cin.sin_port));
                }

	}

	close(fd);

	return 0;
}

对比