server.c

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <netinet/in.h>
#include <arpa/inet.h>   
int main(int argc, char *argv[]) 
{ 
 int sockfd,new_fd; 
 struct sockaddr_in server_addr; 
 struct sockaddr_in client_addr; 
 int sin_size,portnumber; 
 char hello[]="Hello! Are You Fine?\n"; 

 if(argc!=2) 
 { 
  fprintf(stderr,"Usage:%s portnumber\a\n",argv[0]); 
  exit(1); 
 } 
  
 if((portnumber=atoi(argv[1]))<0) 
 { 
    fprintf(stderr,"Usage:%s portnumber\a\n",argv[0]); 
    exit(1); 
 } 

/* 服务器端开始建立socket描述符 */ 
 if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)   
 { 
        fprintf(stderr,"Socket error:%s\n\a",strerror(errno)); 
        exit(1); 
 } 

/* 服务器端填充 sockaddr结构  */  
 bzero(&server_addr,sizeof(struct sockaddr_in)); 
 server_addr.sin_family=AF_INET; 
 server_addr.sin_addr.s_addr=htonl(INADDR_ANY); 
 server_addr.sin_port=htons(portnumber); 
  
/* 捆绑sockfd描述符  */  
 if(bind(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))==-1) 
 { 
        fprintf(stderr,"Bind error:%s\n\a",strerror(errno)); 
        exit(1); 
 } 
  
/* 监听sockfd描述符  */ 
 if(listen(sockfd,5)==-1) 
 { 
        fprintf(stderr,"Listen error:%s\n\a",strerror(errno)); 
        exit(1); 
 } 
 printf("listen ok \n");
 while(1) 
 { 
        /* 服务器阻塞,直到客户程序建立连接  */ 
    sin_size=sizeof(struct sockaddr_in); 
    new_fd=accept(sockfd,(struct sockaddr*)(&client_addr),&sin_size);
    printf("accept ok \n");
    if((-1) == new_fd) 
    { 
        fprintf(stderr,"Accept error:%s\n\a",strerror(errno)); 
        exit(1); 
    } 
    printf("accept ok \n");
    char string[40]; 
    strcpy(string, "Hello, world!\n");
    if(write(new_fd,string,strlen(string))==-1) 
    { 
        fprintf(stderr,"Write Error:%s\n",strerror(errno)); 
        exit(1); 
    } 
/* 这个通讯已经结束     */ 
    close(new_fd); 
/* 循环下一个     */   
  } 
   close(sockfd); 
   exit(0); 
}