/*server.c*/
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <netinet/in.h>
#define SERVPORT 3333
#define BACKLOG 10
#define MAX_CONNECTED_NO 10
#define MAXDATASIZE 5
int main()
{
struct sockaddr_in server_sockaddr,client_sockaddr;
int sin_size,recvbytes;
int sockfd,client_fd;
char buf[MAXDATASIZE];
/*建立socket连接*/
if((sockfd = socket(AF_INET,SOCK_STREAM,0)) == -1){
perror("socket");
exit(1);
}
printf("socket success! sockfd = %d\n", sockfd);
/*设置sockaddr_in结构体相关参数*/
server_sockaddr.sin_family = AF_INET;
server_sockaddr.sin_port = htons(SERVPORT);
server_sockaddr.sin_addr.s_addr = INADDR_ANY;
bzero(&(server_sockaddr.sin_zero),8);
/*绑定函数bind*/
if(bind(sockfd,(struct sockaddr *)&server_sockaddr,sizeof(struct sockaddr)) == -1)
{
perror("bind");
exit(1);
}
printf("bind success!\n");
/*调用listen函数*/
if(listen(sockfd,BACKLOG) == -1)
{
perror("listen");
exit(1);
}
printf("listening...\n");
/*调用accept函数*/
if((client_fd = accept(sockfd,(struct sockaddr *)&client_sockaddr,&sin_size)) == -1)
{
perror("accept");
exit(1);
}
/*调用recv函数接收客户端的请求*/
if((recvbytes = recv(client_fd,buf,MAXDATASIZE,0)) == -1)
{
perror("recv");
exit(1);
}
printf("received a connection : %s\n",buf);
close(sockfd);
}

/*client.c*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#define SERVPORT 3333
#define MAXDATASIZE 100
int main(int argc,char **argv)
{
int sockfd,sendbytes;
char buf[MAXDATASIZE];
struct hostent *host;
struct sockaddr_in serv_addr;
if(argc < 2)
{
fprintf(stderr,"Please enter the sercer‘s hostname!\n");
exit(1);
}
/*地址解析函数*/
if((host = (struct hostent *)gethostname(argv[1]))==NULL){
perror("gethostname");
exit(1);
}
/*创建socket*/
if((sockfd = socket(AF_INET, SOCK_STREAM,0)) == -1)
{
perror("socket");
exit(1);
}
/*设置sockaddr_in结构体相关参数*/
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(SERVPORT);
serv_addr.sin_addr=*((struct in_addr *)host->h_addr);
bzero(&(serv_addr.sin_zero),8);
/*调用connect函数主动发起对服务端的连接*/
if(connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(struct sockaddr)) == -1)
{
perror("connect");
exit(1);
}
/*发送消息给服务器*/
if((sendbytes = send(sockfd,"hello",5,0)) == -1){
perror("send");
exit(1);
}
close(sockfd);
}