环境：linux C
功能：UDP循环服务器
/*server.c*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define port 5001
int main()
{
int fd = -1;
if((fd = socket(AF_INET,SOCK_DGRAM,0)) < 0)
{
perror("socket");
exit(-1);
}
//填充sockaddr_in 结构体
struct sockaddr_in sin;
bzero(&sin,sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_port = htons(port);
sin.sin_addr.s_addr = htonl(INADDR_ANY);
//绑定
if(bind(fd,(const struct sockaddr *)&sin,sizeof(sin)) < 0)
{
perror("bind");
exit(-1);
}
//udp 无需建立连接 所以没有listen() accept()
//直接recvfrom()
char buf[BUFSIZ];
struct sockaddr_in cin;
socklen_t addrlen = sizeof(cin);
while(1)
{
if(recvfrom(fd,buf,BUFSIZ,0,(struct sockaddr *)&cin,&addrlen) < 0 )
{
perror("recvfrom");
continue;
}
char ipv4_addr[16];
if(!inet_ntop(AF_INET,(void *)&cin.sin_addr.s_addr,ipv4_addr,sizeof(cin)))
{
perror("inet_ntop");
continue;
}
if(strncasecmp(buf,"quit\n",4) != 0)
printf("client(%s:%d):%s",ipv4_addr,ntohs(cin.sin_port),buf);
else
printf("client is exiting\n");
}
close(fd);
return 0;
}
/*client.c*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
int main(int argc, char * argv[])
{
if(argc != 3)
{
printf("usage: %s <server_ip> <server_port>\n",argv[0]);
exit(-1);
}
int fd = -1;
if((fd = socket(AF_INET,SOCK_DGRAM,0)) < 0)
{
perror("socket");
exit(-1);
}
struct sockaddr_in sin;
bzero(&sin,sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_port = htons(atoi(argv[2]));
sin.sin_addr.s_addr = inet_addr(argv[1]);
char buf[BUFSIZ];
while(1)
{
bzero(buf,BUFSIZ);
if(fgets(buf,BUFSIZ,stdin) == NULL)
{
perror("fgets");
continue;
}
if(sendto(fd,buf,strlen(buf),0,(const struct sockaddr *)&sin,sizeof(sin)) == -1)
{
perror("sendto");
continue;
}
if(!strncasecmp(buf,"quit\n",4))
break;
}
close(fd);
return 0;
}