TCP套接字網絡程式設計(三)
利用select函數的多路複用機制實作用戶端和伺服器的聊天,這樣的好處時不用循環進行收發函數,隻需要循環select就可以了,select來監聽是否有讀寫操作,有的話會進行讀寫操作,沒有的話根據設定的select等待時間來進行阻塞或是非阻塞操作,這樣可以節省背景資源。
1.server部分
/*
* 檔案:select_server.c
* 題目:
* 注:編譯用如下指令:
* gcc -Wall select_server.c -o server
* gcc -Wall select_client.c -o client
* 運作用如下指令:
* ./server 7838 1
* ./client 127.0.0.1 7838
*/
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define MAXBUF 1024
int main(int argc,char** argv)
{
int sockfd,new_fd;
socklen_t len;
struct sockaddr_in my_addr,their_addr;
unsigned int myport,lisnum;
char buf[MAXBUF+1];
fd_set rfds;
struct timeval tv;
int retval,maxfd = -1;
if(argv[1] && argc >= 2)
myport = atoi(argv[1]);
else
myport = 7838;
if (argv[2] && argc >= 3)
lisnum = atoi(argv[2]);
else
lisnum = 2;
if((sockfd = socket(PF_INET,SOCK_STREAM,0)) == -1)
{
perror("socket");
exit(1);
}
bzero(&my_addr,sizeof(my_addr));
my_addr.sin_family = PF_INET;
my_addr.sin_port = htons(myport);
if(argv[3] && argc >= 4)
my_addr.sin_addr.s_addr = inet_addr(argv[3]);
else
my_addr.sin_addr.s_addr = INADDR_ANY;
if(bind(sockfd,(struct sockaddr*)&my_addr,sizeof(struct sockaddr)) == -1)
{
perror("bind");
exit(1);
}
if(listen(sockfd,lisnum) == -1)
{
perror("listen");
exit(1);
}
while(1)
{
printf("\n----等待新的連接配接到來開始新一輪聊天......\n");
len = sizeof(struct sockaddr);
if ((new_fd = accept(sockfd,(struct sockaddr*)&their_addr,&len))==-1)
{
perror("accept");
exit(errno);
}
else
printf("server:got connection from %s,port %d,socket %d\n",inet_ntoa(their_addr.sin_addr),ntohs(their_addr.sin_port),new_fd);
//開始處理每個新連接配接上的資料接收
printf("\n準備就緒,可以開始新的聊天了......直接輸入消息回車即可發消息給對方\n");
while(1)
{
FD_ZERO(&rfds);
FD_SET(0,&rfds);
maxfd = 0;
FD_SET(new_fd,&rfds);
if(new_fd > maxfd)
maxfd = new_fd;
tv.tv_sec = 1;
tv.tv_usec = 0;
retval = select(maxfd + 1,&rfds,NULL,NULL,&tv);
if(retval == -1)
{
printf("即将退出,select出錯!%s",strerror(errno));
break;
}
else if(retval == 0)
{
printf("沒有任何消息到來,使用者也沒有按鍵,繼續等待......\n");
continue;
}
else
{
if(FD_ISSET(0,&rfds))
{
bzero(buf,MAXBUF + 1);
fgets(buf,MAXBUF,stdin);
if(!strncasecmp(buf,"quit",4))
{
printf("自己請求終止聊天!\n");
break;
}
len = send(new_fd,buf,strlen(buf) - 1,0);
if(len > 0)
printf("消息:%s\t發送成功,共發送了%d個位元組!\n",buf,len);
else
{
printf("消息'%s'發送失敗!錯誤代碼是%d,錯誤資訊是'%s'\n",buf,errno,strerror(errno));
break;
}
}
if(FD_ISSET(new_fd,&rfds))
{
bzero(buf,MAXBUF+1);
len = recv(new_fd,buf,MAXBUF,0);
if(len > 0)
printf("接收消息成功:'%s',共%d個位元組的資料\n",buf,len);
else
{
if(len < 0)
printf("接收消息失敗!錯誤代碼是%d,錯誤資訊是'%s'\n",errno,strerror(errno));
else
printf("對方退出了,聊天終止\n");
break;
}
}
}
}
close(new_fd);
printf("還要和其它連接配接聊天嗎?(no退出)");
fflush(stdout);
bzero(buf,MAXBUF+1);
fgets(buf,MAXBUF,stdin);
if(!strncasecmp(buf,"no",2))
{
printf("終止聊天!\n");
break;
}
}
close(sockfd);
return 0;
}
2.client部分
/*
* 檔案:select_client.c
* 題目:
* 注:編譯用如下指令:
* gcc -Wall select_server.c -o server
* gcc -Wall select_client.c -o client
* 運作用如下指令:
* ./server 7838 1
* ./client 127.0.0.1 7838
*/
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define MAXBUF 1024
int main(int argc,char** argv)
{
int sockfd,len;
struct sockaddr_in dest;
char buffer[MAXBUF+1];
fd_set rfds;
struct timeval tv;
int retval,maxfd = -1;
if(argc != 3)
{
printf("參數格式錯誤!正确用法如下:\n\t\t%sIP位址 端口\n\t比如:\t%s127.0.0.1 80\n此程式用來從某個IP位址的伺服器某個端口接收最多MAXBUF個位元組消息",argv[0],argv[0]);
exit(0);
}
if((sockfd = socket(AF_INET,SOCK_STREAM,0)) < 0)
{
perror("socket");
exit(errno);
}
bzero(&dest,sizeof(dest));
dest.sin_family = AF_INET;
dest.sin_port = htons(atoi(argv[2]));
if(inet_aton(argv[1],(struct in_addr*)&dest.sin_addr.s_addr) == 0)
{
perror(argv[1]);
exit(errno);
}
if(connect(sockfd,(struct sockaddr*)&dest,sizeof(dest))!=0)
{
perror("connect");
exit(errno);
}
printf("\n準備就緒,可以開始聊天了......直接輸入消息回車即可發消息給對方\n");
while(1)
{
FD_ZERO(&rfds);
FD_SET(0,&rfds);
maxfd = 0;
FD_SET(sockfd,&rfds);
if(sockfd > maxfd)
maxfd = sockfd;
tv.tv_sec = 1;
tv.tv_usec = 0;
retval = select(maxfd + 1,&rfds,NULL,NULL,&tv);
if(retval == -1)
{
printf("将退出,select出錯!%s",strerror(errno));
break;
}
else if(retval == 0)
{
printf("沒有任何消息到來,使用者也沒有按鍵,繼續等待......\n");
continue;
}
else
{
if(FD_ISSET(sockfd,&rfds))
{
bzero(buffer,MAXBUF+1);
len = recv(sockfd,buffer,MAXBUF,0);
if(len > 0)
printf("接收消息成功:'%s',共%d個位元組的資料\n",buffer,len);
else
{
if(len < 0)
printf("消息接收失敗!錯誤代碼是%d,錯誤資訊是'%s'\n",errno,strerror(errno));
else
printf("對方退出了,聊天終止!\n");
break;
}
}
if(FD_ISSET(0,&rfds))
{
bzero(buffer,MAXBUF+1);
fgets(buffer,MAXBUF,stdin);
if(!strncasecmp(buffer,"quit",4))
{
printf("自己請求終止聊天!\n");
break;
}
len = send(sockfd,buffer,strlen(buffer)-1,0);
if(len < 0)
{
printf("消息'%s'發送失敗!錯誤代碼是%d,錯誤資訊是'%s'\n",buffer,errno,strerror(errno));
break;
}
else
printf("消息:%s\t發送成功,共發送了%d個位元組\n",buffer,len);
}
}
}
close(sockfd);
return 0;
}
結果:
![](https://img.laitimes.com/img/_0nNw4CM6IyYiwiM6ICdiwiI0gTMx81dsQWZ4lmZf1GLlpXazVmcvwFciV2dsQXYtJ3bm9CX9s2RkBnVHFmb1clWvB3MaVnRtp1XlBXe0xCMy81dvRWYoNHLwEzX5xCMx8FesU2cfdGLwMzX0xiRGZkRGZ0Xy9GbvNGLpZTY1EmMZVDUSFTU4VFRR9Fd4VGdsYTMfVmepNHLrJXYtJXZ0F2dvwVZnFWbp1zczV2YvJHctM3cv1Ce-cmbw5CM0kjN5UDO4UTY3UmYxQ2YyYzXxUTO1QTMyEzLcdDMyIDMy8CXn9Gbi9CXzV2Zh1WavwVbvNmLvR3YxUjLyM3Lc9CX6MHc0RHaiojIsJye.png)