TCP套接字测试2

//client.c 客户端
#include<stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include<unistd.h>
#include <netdb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#define SERVPORT 3333
#define MAXDATASIZE 100
int main(int argc, char *argv[])
{
    int sockfd, recvbytes;
    char buf[MAXDATASIZE];
    char s[50];
    struct hostent *host;
    struct sockaddr_in serv_addr;
    if(argc < 2) 
     {
	  fprintf(stderr,"Please enter the server's hostname!\n");
	  exit(1);	
     }
    if((host=gethostbyname(argv[1]))==NULL)
     {
	  herror("gethostbyname error！");	
	  exit(1);	
     }
    if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)//建立socket --
     { 
	  perror("socket create error！");	
	  exit(1);	
     }
    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);
    if(connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(struct sockaddr)) == -1) //请求连接 --
     {
	  perror("connect error！");
	  exit(1);
     }
    //successful connection
    if((recvbytes=recv(sockfd, buf, MAXDATASIZE, 0)) ==-1)//接收数据 --
     {
	  perror("connect 出错！");
	  exit(1);
     }
    buf[recvbytes] = '\0';
    printf("收到: %s",buf);
    //send another piece of message to server
    send(sockfd, "liu", 3, 0);
    //receive a piece of message "Bingo" or "incorrect username" from server
    int nbytes = recv(sockfd, s, 100, 0);
    s[nbytes] = '\0';
    printf("%s", s);
    close(sockfd);//关闭连接 --
}
 

//server.c 服务端
#include<stdio.h>
#include<stdlib.h>
#include<errno.h>
#include<unistd.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <arpa/inet.h> 
#define SERVPORT 3333
#define BACKLOG 10
int main()
{	
    int sockfd,client_fd;
    int sin_size;
    char s[50];
    struct sockaddr_in my_addr;    
    struct sockaddr_in remote_addr; 
    sockfd = socket(AF_INET, SOCK_STREAM, 0);//建立socket --
    my_addr.sin_family=AF_INET;//AF_INET地址族
    my_addr.sin_port=htons(SERVPORT);//设定端口号(host -> networks)
    my_addr.sin_addr.s_addr = INADDR_ANY;//32位IPv4地址
    bzero(&(my_addr.sin_zero),8); //置前8个字节为0
    if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr)) == -1) 
     {
  	  perror("bind 出错！");		
	  exit(1);	
     }
    if (listen(sockfd, BACKLOG) == -1) //监听socket连接，设置队列中最多拥有连接个数为10  --
     {	
	  perror("listen 出错！");	
        exit(1);     
     }
    while(1)
     {
	  sin_size = sizeof(struct sockaddr_in);//记录sockaddr_in结构体所占字节数
	  if ((client_fd = accept(sockfd, (struct sockaddr *)&remote_addr, &sin_size)) == -1) //accept()缺省是阻塞函数，阻塞到有连接请求为止 --
          {	
	      perror("accept error");		
	      continue;		
	  }
	  printf("收到一个连接来自： %s\n", inet_ntoa(remote_addr.sin_addr));
	  if (!fork()) 
          { 
		if (send(client_fd, "连接上了 \n", 26, 0) == -1) //--		
		    perror("send 出错！");	  
		//receive a piece of message from host
		int nbytes = recv(client_fd, s, 100, 0);
		s[nbytes] = '\0';
		if(s[0] == 'l' && s[1] == 'i' && s[2] == 'u' && nbytes == 3)
		{
		     //send the message "Bingo" to host
		     send(client_fd, "Bingo\n" ,6, 0);
		}
		else
		{
		     //send the message "incorrect username" to host
		     send(client_fd, "incorrect username\n", 26, 0);
		}
            close(client_fd);	
            exit(0);		
          }
	  close(client_fd);
     }
}