聊天室服务器程序

多进程服务器，一个子进程处理一个客户连接，同时将所有客户socket连接的读缓存设计为一块共享内存。

#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <assert.h>#include <stdio.h>#include <unistd.h>#include <errno.h>#include <string.h>#include <fcntl.h>#include <stdlib.h>#include <sys/epoll.h>#include <signal.h>#include <sys/wait.h>#include <sys/mman.h>#include <sys/stat.h>#include <fcntl.h>#define USER_LIMIT 5#define BUFFER_SIZE 1024#define FD_LIMIT 65535#define MAX_EVENT_NUMBER 1024#define PROCESS_LIMIT 65536/** * 处理一个客户端连接必要的数据 */struct client_data {sockaddr_in address;//客户端Socket地址int connfd;//Socket文件描述符pid_t pid;//处理这个连接的子进程的PIDint pipefd[2];//和父进程通信的管道};static const char* shm_name = "/my_shm";int sig_pipefd[2];int epollfd;int listenfd;int shmfd;char* share_mem = 0;//客户连接数组，进程用客户连接的编号来索引这个数组，即可取得相关的客户连接数据client_data* users = 0;//子进程和客户连接的映射关系表，用进程的PID来索引这个数组，即可取得该进程所处理的客户连接int* sub_process = 0;//当前客户数量int user_count = 0;bool stop_child = false;int setnonblocking(int fd) {int old_option = fcntl(fd, F_GETFL);int new_option = old_option | O_NONBLOCK;fcntl(fd, F_SETFL, new_option);return old_option;}void addfd(int epollfd, int fd) {epoll_event event;event.data.fd = fd;event.events = EPOLLIN | EPOLLET;epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &event);setnonblocking(fd);}void sig_handler(int sig) {int save_errno = errno;int msg = sig;send(sig_pipefd[1], (char*) &msg, 1, 0);errno = save_errno;}void addsig(int sig, void(*handler)(int), bool restart = true) {struct sigaction sa;memset(&sa, '\0', sizeof(sa));sa.sa_handler = handler;if (restart) {sa.sa_flags |= SA_RESTART;}sigfillset(&sa.sa_mask);assert( sigaction( sig, &sa, NULL ) != -1 );}void del_resource() {close(sig_pipefd[0]);close(sig_pipefd[1]);close(listenfd);close(epollfd);shm_unlink(shm_name);delete[] users;delete[] sub_process;}//停止一个子进程void child_term_handler(int sig) {stop_child = true;}/** * 子进程运行的函数。参数idx指出该子进程处理的客户连接的编号，users时保存所有客户连接 * 数据的数组，参数share_mem指出共享内存的起始地址 */int run_child(int idx, client_data* users, char* share_mem) {epoll_event events[MAX_EVENT_NUMBER];/* * 子进程使用I/O复用技术来同时监听两个文件描述符，客户端连接Socket，与父进程通信的管道文件 * 描述符 */int child_epollfd = epoll_create(5);assert( child_epollfd != -1 );int connfd = users[idx].connfd;addfd(child_epollfd, connfd);int pipefd = users[idx].pipefd[1];addfd(child_epollfd, pipefd);int ret;//子进程需要设置自己的信号处理函数addsig(SIGTERM, child_term_handler, false);while (!stop_child) {int number = epoll_wait(child_epollfd, events, MAX_EVENT_NUMBER, -1);if ((number < 0) && (errno != EINTR)) {printf("epoll failure\n");break;}for (int i = 0; i < number; i++) {int sockfd = events[i].data.fd;//本子进程负责的客户连接有数据到达if ((sockfd == connfd) && (events[i].events & EPOLLIN)) {memset(share_mem + idx * BUFFER_SIZE, '\0', BUFFER_SIZE);/** * 将客户数据读取到对应的数据缓存中，该读缓存时共享内存的一段，它开始于idx*BUFFER_SIZE 处，长度为BUFFER_SIZE字节，因此，各个客户连接的读缓存时共享的*/ret = recv(connfd, share_mem + idx * BUFFER_SIZE,BUFFER_SIZE - 1, 0);if (ret < 0) {if (errno != EAGAIN) {stop_child = true;}} else if (ret == 0) {stop_child = true;} else {//成功读取客户数据后就通知主进程（通过管道）来处理send(pipefd, (char*) &idx, sizeof(idx), 0);}//主进程通知本进程（通过管道）将第client个客户的数据发送到本进程负责的客户端} else if ((sockfd == pipefd) && (events[i].events & EPOLLIN)) {int client = 0;//接收主进程发送来的数据，即有客户数据到达的连接的编号ret = recv(sockfd, (char*) &client, sizeof(client), 0);if (ret < 0) {if (errno != EAGAIN) {stop_child = true;}} else if (ret == 0) {stop_child = true;} else {send(connfd, share_mem + client * BUFFER_SIZE, BUFFER_SIZE,0);}} else {continue;}}}close(connfd);close(pipefd);close(child_epollfd);return 0;}int main(int argc, char* argv[]) {if (argc <= 2) {printf("usage: %s ip_address port_number\n", basename(argv[0]));return 1;}const char* ip = argv[1];int port = atoi(argv[2]);int ret = 0;struct sockaddr_in address;bzero(&address, sizeof(address));address.sin_family = AF_INET;inet_pton(AF_INET, ip, &address.sin_addr);address.sin_port = htons(port);listenfd = socket(PF_INET, SOCK_STREAM, 0);assert( listenfd >= 0 );ret = bind(listenfd, (struct sockaddr*) &address, sizeof(address));assert( ret != -1 );ret = listen(listenfd, 5);assert( ret != -1 );user_count = 0;users = new client_data[USER_LIMIT + 1];sub_process = new int[PROCESS_LIMIT];for (int i = 0; i < PROCESS_LIMIT; ++i) {sub_process[i] = -1;}epoll_event events[MAX_EVENT_NUMBER];epollfd = epoll_create(5);assert( epollfd != -1 );addfd(epollfd, listenfd);ret = socketpair(PF_UNIX, SOCK_STREAM, 0, sig_pipefd);assert( ret != -1 );setnonblocking(sig_pipefd[1]);addfd(epollfd, sig_pipefd[0]);addsig(SIGCHLD, sig_handler);addsig(SIGTERM, sig_handler);addsig(SIGINT, sig_handler);addsig(SIGPIPE, SIG_IGN);bool stop_server = false;bool terminate = false;//创建共享内存，作为所有客户socket连接的读缓存shmfd = shm_open(shm_name, O_CREAT | O_RDWR, 0666);assert( shmfd != -1 );ret = ftruncate(shmfd, USER_LIMIT * BUFFER_SIZE);assert( ret != -1 );share_mem = (char*) mmap(NULL, USER_LIMIT * BUFFER_SIZE,PROT_READ | PROT_WRITE, MAP_SHARED, shmfd, 0);assert( share_mem != MAP_FAILED );close(shmfd);while (!stop_server) {int number = epoll_wait(epollfd, events, MAX_EVENT_NUMBER, -1);if ((number < 0) && (errno != EINTR)) {printf("epoll failure\n");break;}for (int i = 0; i < number; i++) {int sockfd = events[i].data.fd;//新的客户连接到来if (sockfd == listenfd) {struct sockaddr_in client_address;socklen_t client_addrlength = sizeof(client_address);int connfd = accept(listenfd,(struct sockaddr*) &client_address, &client_addrlength);if (connfd < 0) {printf("errno is: %d\n", errno);continue;}if (user_count >= USER_LIMIT) {const char* info = "too many users\n";printf("%s", info);send(connfd, info, strlen(info), 0);close(connfd);continue;}//保存第user_count个客户连接的相关数据users[user_count].address = client_address;users[user_count].connfd = connfd;//在主进程和子进程间建立管道，以传递必要的数据ret = socketpair(PF_UNIX, SOCK_STREAM, 0,users[user_count].pipefd);assert( ret != -1 );pid_t pid = fork();if (pid < 0) {close(connfd);continue;} else if (pid == 0) {close(epollfd);close(listenfd);close(users[user_count].pipefd[0]);close(sig_pipefd[0]);close(sig_pipefd[1]);run_child(user_count, users, share_mem);munmap((void*) share_mem, USER_LIMIT * BUFFER_SIZE);exit(0);} else {close(connfd);close(users[user_count].pipefd[1]);addfd(epollfd, users[user_count].pipefd[0]);users[user_count].pid = pid;//记录新的客户连接在数组users中的索引值，建立进程PID和该索引值之间的映射关系sub_process[pid] = user_count;user_count++;}//处理信号事件} else if ((sockfd == sig_pipefd[0])&& (events[i].events & EPOLLIN)) {int sig;char signals[1024];ret = recv(sig_pipefd[0], signals, sizeof(signals), 0);if (ret == -1) {continue;} else if (ret == 0) {continue;} else {for (int i = 0; i < ret; ++i) {switch (signals[i]) {//子进程退出，表示有某个客户端关闭了连接case SIGCHLD: {pid_t pid;int stat;while ((pid = waitpid(-1, &stat, WNOHANG)) > 0) {//用子进程的PID取得被关闭的客户连接的编号int del_user = sub_process[pid];sub_process[pid] = -1;if ((del_user < 0) || (del_user > USER_LIMIT)) {printf("the deleted user was not change\n");continue;}//清除第del_user个客户连接使用的相关数据epoll_ctl(epollfd, EPOLL_CTL_DEL,users[del_user].pipefd[0], 0);close(users[del_user].pipefd[0]);users[del_user] = users[--user_count];sub_process[users[del_user].pid] = del_user;printf("child %d exit, now we have %d users\n",del_user, user_count);}if (terminate && user_count == 0) {stop_server = true;}break;}case SIGTERM://结束服务器程序case SIGINT: {printf("kill all the clild now\n");//addsig( SIGTERM, SIG_IGN );//addsig( SIGINT, SIG_IGN );if (user_count == 0) {stop_server = true;break;}for (int i = 0; i < user_count; ++i) {int pid = users[i].pid;kill(pid, SIGTERM);}terminate = true;break;}default: {break;}}}}//某个子进程向父进程写入了数据} else if (events[i].events & EPOLLIN) {int child = 0;//读取管道数据，child变量记录了是哪个客户连接有数据到达ret = recv(sockfd, (char*) &child, sizeof(child), 0);printf("read data from child accross pipe\n");if (ret == -1) {continue;} else if (ret == 0) {continue;} else {//向除负责处理第child个客户连接的子进程之外的其他子进程发送消息，通知它们有客户数据要写for (int j = 0; j < user_count; ++j) {if (users[j].pipefd[0] != sockfd) {printf("send data to child accross pipe\n");send(users[j].pipefd[0], (char*) &child,sizeof(child), 0);}}}}}}del_resource();return 0;}