Linux下socket异步通讯聊天程序（转）
网络课的project 1能用到的资料，程序结构比较清晰，转来学习一下
什么是异步通讯？
就是通讯任意一方可以任意发送消息，有消息来到时会收到系统提示去接收消息。
这里要用到select函数。使用步骤如下：
1、设置一个集合变量，用来存放所有要判断的句柄（file descriptors：即我们建立的每个socket、用open打开的每个文件等）
2、把需要判断的句柄加入到集合里
3、设置判断时间
4、开始等待，即select
5、如果在设定的时间内有任何句柄状态变化了就马上返回，并把句柄设置到集合里
服务器端源代码如下：
#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 <unistd.h>#include <arpa/inet.h>#include <sys/time.h>#include <sys/types.h>?#define MAXBUF 1024/************关于本文档*********************************************filename: async-server.c*purpose: 演示网络异步通讯，这是服务器端程序*wrote by: zhoulifa(zhoulifa@163.com) 周立发(http://zhoulifa.bokee.com)Linux爱好者 Linux知识传播者 SOHO族 开发者 最擅长C语言*date time:2007-01-25 21:22*Note: 任何人可以任意复制代码并运用这些文档，当然包括你的商业用途* 但请遵循GPL*Thanks to: Google.com*Hope:希望越来越多的人贡献自己的力量，为科学技术发展出力* 科技站在巨人的肩膀上进步更快！感谢有开源前辈的贡献！*********************************************************************/?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])????????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 = 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----等待新的连接到来开始新一轮聊天……\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);?????????/* 开始处理每个新连接上的数据收发 */????????printf????????????("\n准备就绪，可以开始聊天了……直接输入消息回车即可发信息给对方\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;????????????/* 开始等待 */????????????retval = select(maxfd + 1, &rfds, NULL, NULL, &tv);????????????if (retval == -1) {????????????????printf("将退出，select出错！ %s", strerror(errno));????????????????break;????????????} else if (retval == 0) {????????????????/* printf???????????????????("没有任何消息到来，用户也没有按键，继续等待……\n"); */????????????????continue;????????????} else {????????????????if (FD_ISSET(0, &rfds)) {????????????????????/* 用户按键了，则读取用户输入的内容发送出去 */????????????????????bzero(buf, MAXBUF + 1);????????????????????fgets(buf, MAXBUF, stdin);????????????????????if (!strncasecmp(buf, "quit", 4)) {????????????????????????printf("自己请求终止聊天！\n");????????????????????????break;????????????????????}????????????????????len = send(new_fd, buf, strlen(buf) - 1, 0);????????????????????if (len > 0)????????????????????????printf????????????????????????????("消息:%s\t发送成功，共发送了%d个字节！\n",?????????????????????????????buf, len);????????????????????else {????????????????????????printf????????????????????????????("消息'%s'发送失败！错误代码是%d，错误信息是'%s'\n",?????????????????????????????buf, errno, strerror(errno));????????????????????????break;????????????????????}????????????????}????????????????if (FD_ISSET(new_fd, &rfds)) {????????????????????/* 当前连接的socket上有消息到来则接收对方发过来的消息并显示 */????????????????????bzero(buf, MAXBUF + 1);????????????????????/* 接收客户端的消息 */????????????????????len = recv(new_fd, buf, MAXBUF, 0);????????????????????if (len > 0)????????????????????????printf????????????????????????????("接收消息成功:'%s'，共%d个字节的数据\n",?????????????????????????????buf, len);????????????????????else {????????????????????????if (len < 0)????????????????????????????printf????????????????????????????????("消息接收失败！错误代码是%d，错误信息是'%s'\n",?????????????????????????????????errno, strerror(errno));????????????????????????else????????????????????????????printf("对方退出了，聊天终止\n");????????????????????????break;????????????????????}????????????????}????????????}????????}????????close(new_fd);????????/* 处理每个新连接上的数据收发结束 */????????printf("还要和其它连接聊天吗？(no->退出)");????????fflush(stdout);????????bzero(buf, MAXBUF + 1);????????fgets(buf, MAXBUF, stdin);????????if (!strncasecmp(buf, "no", 2)) {????????????printf("终止聊天！\n");????????????break;????????}????}?????close(sockfd);????return 0;}客户端源代码如下：
?001002003004005006007008009010011012013014015016017018019020021022023024025026027028029030031032033034035036037038039040041042043044045046047048049050051052053054055056057058059060061062063064065066067068069070071072073074075076077078079080081082083084085086087088089090091092093094095096097098099100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131#include <stdio.h>#include <string.h>#include <errno.h>#include <sys/socket.h>#include <resolv.h>#include <stdlib.h>#include <netinet/in.h>#include <arpa/inet.h>#include <unistd.h>#include <sys/time.h>#include <sys/types.h>?#define MAXBUF 1024/************关于本文档********************************************// *filename: ssync-client.c*purpose: 演示网络异步通讯，这是客户端程序*wrote by: zhoulifa(zhoulifa@163.com) 周立发(http://zhoulifa.bokee.com)Linux爱好者 Linux知识传播者 SOHO族 开发者 最擅长C语言*date time:2007-01-25 21:32*Note: 任何人可以任意复制代码并运用这些文档，当然包括你的商业用途* 但请遵循GPL*Thanks to: Google.com*Hope:希望越来越多的人贡献自己的力量，为科学技术发展出力* 科技站在巨人的肩膀上进步更快！感谢有开源前辈的贡献！*********************************************************************/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????????????("参数格式错误！正确用法如下：\n\t\t%s IP地址 端口\n\t比如:\t%s 127.0.0.1 80\n此程序用来从某个 IP 地址的服务器某个端口接收最多 MAXBUF 个字节的消息",?????????????argv[0], argv[0]);????????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);????}?????/* 连接服务器 */????if (connect(sockfd, (struct sockaddr *) &dest, sizeof(dest)) != 0) {????????perror("Connect ");????????exit(errno);????}?????printf????????("\n准备就绪，可以开始聊天了……直接输入消息回车即可发信息给对方\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sockfd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("将退出，select出错！ %s", strerror(errno));????????????break;????????} else if (retval == 0) {????????????/* printf???????????????("没有任何消息到来，用户也没有按键，继续等待……\n"); */????????????continue;????????} else {????????????if (FD_ISSET(sockfd, &rfds)) {????????????????/* 连接的socket上有消息到来则接收对方发过来的消息并显示 */????????????????bzero(buffer, MAXBUF + 1);????????????????/* 接收对方发过来的消息，最多接收 MAXBUF 个字节 */????????????????len = recv(sockfd, buffer, MAXBUF, 0);????????????????if (len > 0)????????????????????printf????????????????????????("接收消息成功:'%s'，共%d个字节的数据\n",?????????????????????????buffer, len);????????????????else {????????????????????if (len < 0)????????????????????????printf????????????????????????????("消息接收失败！错误代码是%d，错误信息是'%s'\n",?????????????????????????????errno, strerror(errno));????????????????????else????????????????????????printf("对方退出了，聊天终止！\n");????????????????????break;????????????????}????????????}????????????if (FD_ISSET(0, &rfds)) {????????????????/* 用户按键了，则读取用户输入的内容发送出去 */????????????????bzero(buffer, MAXBUF + 1);????????????????fgets(buffer, MAXBUF, stdin);????????????????if (!strncasecmp(buffer, "quit", 4)) {????????????????????printf("自己请求终止聊天！\n");????????????????????break;????????????????}????????????????/* 发消息给服务器 */????????????????len = send(sockfd, buffer, strlen(buffer) - 1, 0);????????????????if (len < 0) {????????????????????printf????????????????????????("消息'%s'发送失败！错误代码是%d，错误信息是'%s'\n",?????????????????????????buffer, errno, strerror(errno));????????????????????break;????????????????} else????????????????????printf????????????????????????("消息：%s\t发送成功，共发送了%d个字节！\n",?????????????????????????buffer, len);????????????}????????}????}????/* 关闭连接 */????close(sockfd);????return 0;}编译用如下命令：
gcc -Wall async-server.c -o server
gcc -Wall async-client.c -o client
运行用如下命令：
./server 7838 1
./client 127.0.0.1 7838