Linux服务器、客户端

#include <stdio.h>         //标准输入输出头文件
#include <sys/socket.h>    //与套接字相关的函数声明和结构定义
#include <netinet/in.h>    //某些结构体声明、宏定义
#include <arpa/inet.h>    //某些函数声明
#include <errno.h>      //查看错误代码
/*以上为包含必要的头文件，其中几个头文件是几乎每一个网络程序所必需的，如<sys/socket.h>，<netinet/in.h>等*/

int main(int argc,char *argv[])
{
 printf("=======================================\n");
 printf("=       My first server program       =\n");
 printf("=======================================\n");

 int sockfd,new_fd;
 struct sockaddr_in server_addr;
 struct sockaddr_in client_addr;
 int sin_size,portnumber;
 char hello[]="Hello, The Network! This is my first Server.\n";

 if (argc!=2){
   fprintf(stderr,"Usage:%s  portnumber \a\n",argv[0]);
   exit(1);  //程序出现错误结束
 }

if ((portnumber=atoi(argv[1]))<0){
   fprintf(stderr,"Usage:%s  portnumber \a\n",argv[0]);
   exit(1);
 }   //atoi()将字符型转化为整型

 //建立socket描述符（intnet协议簇，流套接字，使用默认协议）
 if ((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1){
   fprintf(stderr,"Socket error:%s \a\n",strerror(errno));
   exit(1);
 }
//填充服务器的套接字地址结构sockaddr
 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);

 //开始捆绑sockfd描述符
 if (bind(sockfd,(struct sockaddr *)(&server_addr),sizeof (struct sockaddr))==-1){
   fprintf(stderr,"Bind error:%s \a\n",strerror(errno));
   exit(1);
 }

 //监听sockfd描述符
if (listen(sockfd,5)==-1){
   //fprintf(stderr,"Listen error:%s \a\n",strerror(errno));
   exit(1);
 } 

 while(1) {
//阻塞服务器，直到客户程序建立连接
   sin_size=sizeof (struct sockaddr_in);
   if ((new_fd=accept(sockfd,(struct sockaddr*)(&client_addr),&sin_size))==-1){
     //fprintf(stderr,"Accept error:%s \a\n",strerror(errno));
     exit(1);
   }

     fprintf(stderr,"Server get connection from %s :\n",inet_ntoa(client_addr.sin_addr));
     if (write(new_fd,hello,strlen(hello))==-1){
       //fprintf(stderr,"Write error:%s \a\n",strerror(errno));
       exit(1);    
     }
     //通信结束,继续循环执行
     close(new_fd);
/*当服务器处理完这个客户机请求后，关闭连接套接字*/ 
}
//关闭监听套接字描述符
 close(sockfd);
 exit(0);
   
}

#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <netdb.h>     /*包括结构hostent（主机环境），获得主机信息的几个函数*/

int main(int argc,char *argv[])
{
 printf("=======================================\n");
 printf("=       My first client program!      =\n");
 printf("=======================================\n");

 int sockfd,new_fd;
 struct sockaddr_in server_addr;
 struct hostent *host;
 int nbytes,portnumber;
 char buffer[1024];

 if (argc!=3){
   fprintf(stderr,"Usage:%s hostname portnumber \a\n",argv[0]);
   exit(1);
 }

//获得服务器地址
 if ((host=gethostbyname(argv[1]))==NULL){
   fprintf(stderr,"HostName Erro!");
   exit(1);
 }

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

 //建立客户端Sockfd描述符
 if ((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1){
   fprintf(stderr,"Socket error:%s \a\n",strerror(errno));
   exit(1);
 }

//调用函数connect之前，需要指定服务器进程的套接字地址
//填充sockaddr结构
 bzero(&server_addr,sizeof (struct sockaddr_in));
 server_addr.sin_family=AF_INET;
 server_addr.sin_port=htons(portnumber);
// server_addr.sin_addr= *((struct in_addr *) host->h_addr);

//发起连接请求与远程服务器建立一个连接
 if (connect(sockfd,(struct sockaddr *)(&server_addr),sizeof (struct sockaddr))==-1){
   fprintf(stderr,"Bind error:%s \a\n",strerror(errno));
   exit(1);
 }

 //进行读写数据操作，将数据显示到标准输出上
 if ((nbytes=read(sockfd,buffer,1024))==-1){
   fprintf(stderr,"Read error: %s  \n",strerror(errno));
   exit(1);
 }
 
 buffer[nbytes]=‘\\‘;
   printf("收到: %s \n",buffer);
//结束通信
//关闭连接
 close(sockfd);
 exit(0);
   
}