Linux下select异步通讯如何实现

1.服务器端

/*select_server.c 2011.9.2 by yyg*/ #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <netinet/in.h> #include <sys/socket.h> #include <sys/wait.h> #include <pthread.h> #include <sys/wait.h> #include <sys/time.h> #include <arpa/inet.h> #include <unistd.h> #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（argv[1]){ myport = atoi(argv[1]); } else myport = 7838; if(argv[2]){ 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]) 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----waiting for new connecting to start new char----\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,socked %d\n",\ inet_ntoa(their_addr.sin_addr),\ ntohs(their_addr.sin_port),new_fd); /*开始处理每个新连接上的数据收发*/ //printf("\n---ready to go.now you can chatting...input enter,then you can chat---\n"); while(1){ /*把集合清空*/ FD_ZERO(&rfds); /*把标准输入句柄0加入到集合中*/ FD_SET(0,&rfds); maxfd = 0; /*把当前连接句柄new_fd加入到集合中*/ FD_SET(new_fd,&rfds); if(new_fd > maxfd) maxfd = new_fd; /*设置最大等待时间*/ tv.tv_sec = 1; tv.tv_usec = 0; retval = select(maxfd+1,&rfds,NULL,NULL,&tv); if(retval == -1){ printf("select error!%s\n",strerror(errno)); break; } else if(retval == 0){ //printf("no message come,user no press the button,please wait...\n"); continue; } else{ if(FD_ISSET(new_fd,&rfds)){ /*连接的socket 上有消息则接收并显示*/ bzero(buf,MAXBUF+1); /*接收对方发过来的消息，最多MAXBUF字节*/ len = recv(new_fd, buf, MAXBUF, 0); if(len > 0) printf("recv msg success:%s! %d bytes rcv.\n ",buf,len); else{ if(len < 0){ printf("recv msg fail.the errno is:%d,error info is %s.\n",errno,strerror(errno)); } else printf("quit.\n"); break; } }// FD_ISSET = sockfd情况 if(FD_ISSET(0,&rfds)){ /*用户有输入了，则读取其内容并发送*/ bzero(buf, MAXBUF+1); fgets(buf, MAXBUF, stdin); if(!strncasecmp(buf, "quit", 4)){ printf("self request to quit the chating\n"); break; } /*发消息给服务器*/ len = send(new_fd, buf, strlen(buf)-1 , 0); if(len < 0){ printf("mgs:%s send fail!errno is:%d,error info is:%s\n", buf, errno, strerror(errno)); break; }else{ printf("msg: %s\t send success, send %d bytes!\n", buf, len); } }//FD_ISSET = 0 }//select 处理结束 }/*内while*/ close(new_fd); /*处理每个新连接上的数据收发结束*/ printf("would you want to chatting with another one?(no->quit)"); fflush(stdout); bzero(buf,MAXBUF+1); fgets(buf,MAXBUF,stdin); if(!strncasecmp(buf,"no",2)){ printf("quit the chatting!\n"); break; } }/*外while*/ close(sockfd); return 0; }

2.客户端

/*select_client.c 2011.9.2 by yyg*/ #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <netinet/in.h> #include <sys/socket.h> #include <sys/wait.h> #include <pthread.h> #include <sys/time.h> #include <arpa/inet.h> #include <unistd.h> #include <resolv.h> #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（argc != 3){ printf("the param style wrong!\n"); exit(0); } /*创建一个socket用于tcp通信*/ if((sockfd = socket(AF_INET,SOCK_STREAM,0)) < 0){ perror("socket"); exit(errno); } /*初始化服务器端(对方)的地址和端口信息*/ 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); } /*conect to the server*/ if(connect(sockfd,(struct sockaddr*)&dest,sizeof(dest)) !=0){ perror("connect"); exit(errno); } printf("\n---ready to chatting...---\n"); while(1){ /*把集合清空*/ FD_ZERO(&rfds); /*把标准输入句柄0加入到集合中*/ FD_SET(0,&rfds); maxfd = 0; /*把当前连接句柄socket 加入到集合中*/ FD_SET(sockfd,&rfds); if(sockfd > maxfd) maxfd = sockfd; /*设置最大等待时间*/ tv.tv_sec = 1; tv.tv_usec = 0; /*开始等待*/ retval = select(maxfd+1,&rfds,NULL,NULL,&tv); if(retval == -1){ printf("select error,quit!\n"); break; }else if(retval == 0){ continue; }else{ if(FD_ISSET(sockfd,&rfds)){ /*连接的socket 上有消息则接收并显示*/ bzero(buffer,MAXBUF+1); /*接收对方发过来的消息，最多MAXBUF字节*/ len = recv(sockfd, buffer, MAXBUF, 0); if(len > 0) printf("recv msg success:%s! %d bytes rcv.\n ",buffer,len); else{ if(len < 0){ printf("recv msg fail.the errno is:%d,error info is %s.\n",errno,strerror(errno)); } else printf("quit.\n"); break; } }// FD_ISSET = sockfd情况 if(FD_ISSET(0,&rfds)){ /*用户有输入了，则读取其内容并发送*/ bzero(buffer, MAXBUF+1); fgets(buffer, MAXBUF, stdin); if(!strncasecmp(buffer, "quit", 4)){ printf("self request to quit the chating\n"); break; } /*发消息给服务器*/ len = send(sockfd, buffer, strlen(buffer)-1 , 0); if(len < 0){ printf("mgs:%s send fail!errno is:%d,error info is:%s\n", buffer, errno, strerror(errno)); break; }else{ printf("msg: %s\t send success, send %d bytes!\n", buffer, len); } }//FD_ISSET = 0 }//select 处理结束 }//处理聊天的while 循环 /*关闭连接*/ close(sockfd); return 0; }

运行结果：

终端1：服务器端

[root@localhost net]# ./select_server 7838 ----waiting for new connecting to start new char---- server:got connection from 172.31.100.236,port 59462,socked 4 recv msg success:kfldsjfk! 8 bytes rcv. 456354 msg: 456354 send success, send 6 bytes! recv msg success:453455! 6 bytes rcv.

终端2：客户端

[root@localhost net]# ./select_client 172.31.100.236 7838 ---ready to chatting...--- kfldsjfk msg: kfldsjfk send success, send 8 bytes! recv msg success:456354! 6 bytes rcv. 453455 msg: 453455 send success, send 6 bytes!

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