/***sever***/  
#include <sys/types.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <arpa/inet.h> 
#include <unistd.h> 
#include <sys/select.h> 
#include <stdlib.h> 
#include <stdio.h> 
#include <string.h> 
#define PORT 1234 
#define MAXSOCKFD 10 
void main() 
{ 
 
int sockfd,newsockfd,is_connected[MAXSOCKFD],fd; 
 
struct sockaddr_in addr; 
 
int addr_len = sizeof(struct sockaddr_in); 
 
fd_set readfds; 
 
char buffer[256]; 
 
char msg[ ] ="Welcome to server!"; 
 
pid_t pid; 
 
if ((sockfd = socket(AF_INET,SOCK_STREAM,0))<0) 
 
{ 
 
 
perror("socket"); 
 
 
exit(1); 
 
} 
 
bzero(&addr,sizeof(addr)); 
 
addr.sin_family =AF_INET; 
 
addr.sin_port = htons(PORT); 
 
addr.sin_addr.s_addr = htonl(INADDR_ANY); 
 
if(bind(sockfd,&addr,sizeof(addr))<0) 
 
{ 
 
 
perror("connect"); 
 
 
exit(1); 
 
} 
 
if(listen(sockfd,3)<0) 
 
{ 
 
 
perror("listen"); 
 
 
exit(1); 
 
} 
 
while(1) 
 
{ 
 
 
FD_ZERO(&readfds); 
 
 
if((newsockfd = accept (sockfd,&addr,&addr_len))<0)  
 
 
{ 
 
 
 
perror("accept"); 
 
 
 
continue;  
 
 
}  
 
 
 
if ((pid = fork()) != 0) 
 
 
{ 
 
 
 
close(newsockfd); 
 
 
 
 
continue;  
 
 
}  
 
 
FD_SET(newsockfd, &readfds);  
 
 
printf("cnnect from %s\n",inet_ntoa(addr.sin_addr)); 
 
 
printf("pid = %d, ppid = %d\n", getpid(), getppid()); 
 
 
write(newsockfd,msg,sizeof(msg)); 
 
 
while(1) 
  
  
{ 
  
 
 
 
/*
描述符無變化，資料將阻塞
*/ 
 
 
 
if (!select(MAXSOCKFD, &readfds, NULL, NULL, 0)) 
 
 
 
{ 
 
 
 
 
continue; 
 
 
 
} 
 
 
 
if(read(newsockfd,buffer,sizeof(buffer))<=0) 
 
 
 
{ 
 
 
 
 
printf("connect closed.\n"); 
 
 
 
 
close(newsockfd); 
 
 
 
 
break; 
 
 
 
} 
 
 
 
else 
 
 
 
{ 
 
 
 
 
printf("From client: %d\n",buffer[0]); 
 
 
 
 
if (write(newsockfd, buffer, strlen(buffer)) < 0) 
 
 
 
 
 
perror("write"); 
 
 
 
 
printf("To client: %d\n\n",buffer[0]); 
 
 
 
} 
 
 
 
 
 
} 
 
 
} 
} 
 
  
/****client****/ 
#include <sys/stat.h> 
#include <fcntl.h> 
#include <unistd.h> 
#include <sys/types.h>  
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <arpa/inet.h> 
#include <stdlib.h> 
#include <stdio.h> 
#define PORT 1234  
#define SERVER_IP "127.0.0.1" 
main() 
{ 
 
int s; 
 
struct sockaddr_in addr; 
 
char buffer[256]; 
 
static int flag = 1; 
 
if((s = socket(AF_INET,SOCK_STREAM,0))<0) 
 
{ 
 
 
perror("socket"); 
 
 
exit(1); 
 
} 
 
/* 
填寫
sockaddr_in
結構
*/ 
 
bzero(&addr,sizeof(addr)); 
 
addr.sin_family = AF_INET; 
 
addr.sin_port=htons(PORT); 
 
addr.sin_addr.s_addr = inet_addr(SERVER_IP); 
 
/* 
嘗試連線
*/ 
 
if(connect(s,&addr,sizeof(addr))<0) 
 
{ 
 
 
perror("connect"); 
 
 
exit(1); 
 
} 
 
/* 
接收由
server
端傳來的資訊
*/ 
 
recv(s,buffer,sizeof(buffer),0); 
 
printf("%s\n",buffer); 
 
while(1) 
 
{ 
 
 
bzero(buffer,sizeof(buffer)); 
 
 
/* 
從標準輸入裝置取得字串
*/ 
 
 
if (flag == 1) 
 
 
{ 
 
 
 
read(STDIN_FILENO,buffer,sizeof(buffer)); 
 
 
 
printf("Insert data:%s\n", buffer); 
 
 
 
 
flag = 0; 
 
 
} 
 
 
else 
  
  
{ 
  
 
 
 
read(s,buffer,sizeof(buffer)); 
 
 
 
 
printf("From sever: %d\n\n", buffer[0]); 
  
 
 
}  
 
 
/* 
將字串傳給
server
端
*/ 
 
 
sleep(2);  
 
 
buffer[0] += 1;  
 
 
if(write(s,buffer,sizeof(buffer))<0) 
 
 
{ 
 
 
 
perror("send"); 
 
 
 
exit(1); 
 
 
}  
 
 
printf("To sever: %d\n", buffer[0]); 
  
 
}  
}