一个简单的服务器客服端通信

/*client.cpp*/
#include <iostream>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <errno.h>
#include <string.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netdb.h>

using namespace std;

int main(int argc,char *argv[])
{
int sockfd;
char buffer[1024];
sockaddr_in server_addr;
hostent *host;
int portNumber,nbytes;

if(argc!=3)
{
cout<<"Usage:"<<argv[0]<<" hostname portnumber"<<endl;
exit(1);
}

if((host=gethostbyname(argv[1]))==NULL)
{
cout<<"Get hostname error"<<endl;
exit(1);
}

if((portNumber=atoi(argv[2]))<0)
{
cout<<"Usage:"<<argv[0]<<" hostname portnumber"<<endl;
exit(1);
}

/*客户开始建立sockfd描述符*/
if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)
{
cout<<"Socket error: "<<strerror(errno)<<endl;
exit(1);
}

/*客户程序填充服务端的资料*/
bzero(&server_addr,sizeof(server_addr));
server_addr.sin_family=AF_INET;
server_addr.sin_port=htons(portNumber);
server_addr.sin_addr=*((in_addr*)host->h_addr);

/*客户程序发起连接请求*/
if(connect(sockfd,(sockaddr*)(&server_addr),sizeof(sockaddr))==-1)
{
cout<<"Connect error:"<<strerror(errno)<<endl;
exit(1);
}

/*连接成功了*/
if((nbytes=read(sockfd,buffer,1024))==-1)
{
cout<<"Read error: "<<strerror(errno)<<endl;
exit(1);
}
buffer[nbytes]='\0';
cout<<"I nave received:"<<buffer<<endl;

/*结束通讯*/
close(sockfd);
exit(0);
}

/*server.cpp*/
#include <iostream>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <errno.h>
#include <string.h>
#include <arpa/inet.h>
#include <unistd.h>
using namespace std;

int main(int argc,char *argv[])
{
int sockfd,new_fd; //socket 描述符
struct sockaddr_in server_addr;
struct sockaddr_in client_addr;
int portNumber;
socklen_t sin_size;
char hello[]="Hello!Are You Fine?\n";

if(argc!=2)
{
cout<<"Usage:"<<argv[0]<<" portNumber"<<endl;
exit(1);
}

if((portNumber=atoi(argv[1]))<0)
{
cout<<"Usage:"<<argv[0]<<" portNumber"<<endl;
exit(1);
}

/*服务器端开始建立socket描述符*/
if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)
{
cout<<"Socket error:"<<strerror(errno)<<endl;
exit(1);
}

/*服务器填充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socket描述符*/
if(bind(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))==-1)
{
cout<<"Bind error:"<<strerror(errno);
exit(1);
}

/*监听sockfd描述符*/
if(listen(sockfd,5)==-1) //5为套接字排队的最大连接个数
{
cout<<"Listen error:"<<strerror(errno)<<endl;
exit(1);
}

while(1)
{
/*服务器阻塞，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)
{
cout<<"Accept error:"<<strerror(errno)<<endl;
exit(1);
}
cout<<"Server get connection from "<<inet_ntoa(client_addr.sin_addr)<<endl;
if(write(new_fd,hello,strlen(hello))==-1)
{
cout<<"Write error:"<<strerror(errno)<<endl;
exit(1);
}

/*这个通讯已经结束*/
close(new_fd);

/*循环下一个*/
}
close(sockfd);
exit(0);
}