UDP网络编程实例

这个程序用来实现两个两个系统之间的udp通信，跨平台的，比如两个arm开发板之间，pc和开发板之间。

#include <sys/types.h> 
#include <sys/socket.h> 
#include <arpa/inet.h> 
#include <stdio.h> 
#define BUFLEN 255 
int main(int argc, char **argv) 
{ 
	struct sockaddr_in peeraddr, /*存放谈话对方IP和端口的socket地址*/ 
	localaddr;/*本端socket地址*/ 
	int sockfd; 
	char recmsg[BUFLEN+1]; 
	int socklen, n; 
	if(argc!=5)
	{ 
		printf("%s <dest IP address><dest port><source IP address><source port>\n", argv[0]); 
		exit(0); 
	} 
	sockfd = socket(AF_INET, SOCK_DGRAM, 0); 
	if(sockfd<0)
	{ 
		printf("socket creating err in udptalk\n"); 
		exit(1); 
	} 
	socklen = sizeof(struct sockaddr_in); 
	memset(&peeraddr, 0, socklen); 
	peeraddr.sin_family=AF_INET; 
	peeraddr.sin_port=htons(atoi(argv[2]));

	if(inet_pton(AF_INET, argv[1], &peeraddr.sin_addr)<=0)
	{ 
		printf("Wrong dest IP address!\n"); 
		exit(0); 
	} 
	memset(&localaddr, 0, socklen); 
	localaddr.sin_family=AF_INET;
	if(inet_pton(AF_INET, argv[3], &localaddr.sin_addr)<=0)
	{ 
		printf("Wrong source IP address!\n"); 
		exit(0); 
	} 
	localaddr.sin_port=htons(atoi(argv[4])); 
	if(bind(sockfd, &localaddr, socklen)<0)
	{ 
		printf("bind local address err in udptalk!\n"); 
		exit(2); 
	} 
	if(fgets(recmsg, BUFLEN, stdin) == NULL) exit(0); 
	if(sendto(sockfd, recmsg, strlen(recmsg), 0, &peeraddr, socklen)<0)
	{ 
		printf("sendto err in udptalk!\n"); exit(3); 
	} 

	for(;;)
	{ /*recv&send message loop*/ 
		n = recvfrom(sockfd, recmsg, BUFLEN, 0, &peeraddr, &socklen); 
	if(n<0)
	{ 
		printf("recvfrom err in udptalk!\n"); exit(4); 
	}
	else
	{ /*成功接收到数据报*/ 
		recmsg[n]=0; 
		printf("peer:%s", recmsg); 
	} 
	if(fgets(recmsg, BUFLEN, stdin) == NULL) exit(0); 
	if(sendto(sockfd, recmsg, strlen(recmsg), 0, &peeraddr, socklen)<0)
	{ 
		printf("sendto err in udptalk!\n"); exit(3); 
	} 
	} 
}

编译后，这样使用：

比如主机ip为192.168.1.231，开发板ip为192.168.1.1

在主机上：

./udptak 192.168.1.1 2000 192.168.1.231 2000

在开发板上：

./udptak 192.168.1.231 2000 192.168.1.1 2000

注：2000是端口号

然后你就可以发送数据了。

比如