UDP server/client实例

#include<stdio.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<string.h>

#define SIZE 300

int main(int argc,char *argv[])
{
	int server_sock,r;
	struct sockaddr_in server_addr,client_addr;
	socklen_t len;
	char buf[SIZE];
	if(argc!=2)
	{
		printf("need port\n");
		return 1;
	}
	server_sock = socket(AF_INET,SOCK_DGRAM,0);
	memset(&server_addr,0,sizeof server_addr);
	server_addr.sin_family=AF_INET;
	server_addr.sin_addr.s_addr=htonl(INADDR_ANY);
	server_addr.sin_port=htons(atoi(argv[1]));
	if(-1 == bind(server_sock, (struct sockaddr*)&server_addr,sizeof(server_addr)))
	{
		printf(" bind error\n");
		return -1;
	}
	
 // printf("new client ip:%s, port:%d\n",inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port));	
	while(1)
	{
	    memset(buf,0,sizeof(buf));
	    r = recvfrom(server_sock,buf,sizeof(buf),0,(struct sockaddr*)&client_addr,&len);
		if(r <0)
		{
		    printf("recv error\n");
		 	return 3;
		}	   
		buf[r]='\0';
		printf("recvfrom client ip:%s, port:%d  len=%d, %s\n",inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port),r,buf);
		r = sendto(server_sock,buf,r,0,(struct sockaddr*)&client_addr,len);
		if(r != strlen(buf))
		{
		    printf("sendto error\n");
		 	return 3;
		}
		printf("write len=%d\n",r);       
	}
	close(server_sock);
	
	return 0;
}

#include<stdio.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<string.h>

#define SIZE 300

int main(int argc,char *argv[])
{
	char buf[SIZE];
	if(argc!=3)
	{
		printf("ip + port\n");
		return 1;
	}
	int sock,r;
	struct sockaddr_in addr;
	memset(&addr,0,sizeof(addr));
	socklen_t len;
	sock=socket(AF_INET,SOCK_DGRAM,0);
	
	addr.sin_family=AF_INET;
	addr.sin_addr.s_addr=inet_addr(argv[1]);
	addr.sin_port=htons(atoi(argv[2]));
	
	len=sizeof addr;

	
	//printf("new client ip:%s, port:%d\n",inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port));	
	while(1)
	{
	    memset(buf,0,sizeof(buf));
		printf("input:");
		scanf("%s",buf);
		
		r = sendto(sock,buf,strlen(buf),0,(struct sockaddr*)&addr,len);
		if(r != strlen(buf))
		{
		    printf("sendto error\n");
		 	return 3;
		}
		printf("write len=%d\n",r);  
		
	    r = recvfrom(sock,buf,sizeof(buf),0,NULL,NULL);
		if(r <0)
		{
		    printf("recv error\n");
		 	return 3;
		}	   
		buf[r]='\0';
		printf("recvfrom len=%d,%s\n",r,buf);
		     
	}
	close(sock);
	
	return 0;
}