I/O复用的高级应用二：聊天室程序

chat_client.cc

#define _GNU_SOURCE 1   //为了在poll.h中得到POLLRDHUP标志位的定义
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <poll.h>
#include <fcntl.h>

#define BUFFER_SIZE 64

int main(int argc, char* argv[]){
    if(argc < 2){
        printf("usage: %s ip port\n", basename(argv[0]));
        return 1;
    }
    const char* ip = argv[1];
    int port = atoi(argv[2]);

    struct sockaddr_in server_address;
    bzero(&server_address, sizeof(server_address));
    server_address.sin_family = AF_INET;
    inet_pton(AF_INET, ip, &server_address.sin_addr);
    server_address.sin_port = htons(port);

    int sockfd = socket(PF_INET, SOCK_STREAM, 0);
    assert(sockfd >= 0);
    if(connect(sockfd, (struct sockaddr*)&server_address, sizeof(server_address)) < 0){
        printf("connection failed\n");
        close(sockfd);
        return 1;
    }

    pollfd fds[2];
    fds[0].fd = 0;
    fds[0].events = POLLIN;
    fds[0].revents = 0;
    fds[1].fd = sockfd;
    fds[1].events = POLLIN | POLLRDHUP;
    fds[1].revents = 0;

    char read_buf[BUFFER_SIZE];
    int  pipefd[2];
    int ret = pipe(pipefd);
    assert(ret != -1);

    while(1){
        ret = poll(fds, 2, -1);
        if(ret < 0){
            printf("poll failure\n");
            break;
        }
        if(fds[1].revents & POLLRDHUP){
            printf("server close the connection\n");
            break;
        }
        else if(fds[1].revents & POLLIN){
            memset(read_buf, '\0', BUFFER_SIZE);
            recv(fds[1].fd, read_buf, BUFFER_SIZE-1, 0);
            printf("%s\n",read_buf);
        }
        if(fds[0].revents & POLLIN){
            ret = splice(0, NULL, pipefd[1], NULL, 32768, SPLICE_F_MORE | SPLICE_F_MOVE);
            ret = splice(pipefd[0], NULL, sockfd, NULL, 32768, SPLICE_F_MORE | SPLICE_F_MOVE);
        }
    }
    close(sockfd);
    return 0;
}

chat_server.cc

#define _GUN_SOURCE 1
#include <sys/types.h>
#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 <poll.h>

#define USER_LIMIT      5
#define BUFFER_SIZE     64
#define FD_LIMIT        65535

struct client_data{
    sockaddr_in address;
    char* write_buf;
    char buf[BUFFER_SIZE];
};

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;
}

int main(int argc, char* argv[]){
    if(argc <= 2){
        printf("usage: %s ip port\n", basename(argv[0]));
        return 1;
    }
    const char* ip = argv[1];
    int port = atoi(argv[2]);

    struct sockaddr_in server_address;
    bzero(&server_address, sizeof(server_address));
    server_address.sin_family = AF_INET;
    inet_pton(AF_INET, ip, &server_address.sin_addr);
    server_address.sin_port = htons(port);

    int listenfd = socket(PF_INET, SOCK_STREAM, 0);
    assert(listenfd >= 0);

    int ret = bind(listenfd, (struct sockaddr*)&server_address, sizeof(server_address));
    assert(ret != -1);

    ret = listen(listenfd, USER_LIMIT);
    assert(ret != -1);

    client_data* users = new client_data[FD_LIMIT];

    pollfd fds[USER_LIMIT+1];
    int user_counter = 0;
    for(int i = 1; i <= USER_LIMIT; i++){
        fds[i].fd = -1;
        fds[i].events = 0;
    }
    fds[0].fd = listenfd;
    fds[0].events = POLLIN | POLLERR;
    fds[0].revents = 0;

    while(1){
        ret = poll(fds, user_counter+1, -1);
        if(ret < 0){
            printf("poll failure\n");
            break;
        }
        for(int i = 0; i < user_counter+1; ++i){
            if((fds[i].fd == listenfd) && (fds[i].revents & POLLIN)){
                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", errno);
                    continue;
                }
                if(user_counter >= USER_LIMIT){
                    const char* info = "too many user\n";
                    printf("%s", info);
                    send(connfd, info, strlen(info), 0);
                    close(connfd);
                    continue;
                }
                user_counter++;
                users[connfd].address = client_address;
                setnonblocking(connfd);
                fds[user_counter].fd = connfd;
                fds[user_counter].events = POLLIN | POLLRDHUP | POLLERR;
                fds[user_counter].revents = 0;
                printf("comes a new user, now have %d users\n", user_counter);
            }
            else if(fds[i].revents & POLLERR){
                printf("get an error from %d\n", fds[i].fd);
                char errors[100];
                memset(errors, '\0', 100);
                socklen_t length = sizeof(errors);
                if(getsockopt(fds[i].fd, SOL_SOCKET, SO_ERROR, &errors, &length) < 0){
                    printf("get socket option failure\n");
                }
                continue;
            }
            else if(fds[i].revents & POLLRDHUP){
                users[fds[i].fd] = users[fds[user_counter].fd];
                close(fds[i].fd);
                fds[i] = fds[user_counter];
                user_counter--;
                printf("a client left\n");
            }
            else if(fds[i].revents & POLLIN){
                int connfd = fds[i].fd;
                memset(users[connfd].buf, '\0', BUFFER_SIZE);
                ret = recv(connfd, users[connfd].buf, BUFFER_SIZE-1, 0);
                printf("get %d bytes of client data %s from %d\n", ret, users[connfd].buf, connfd);
                if(ret < 0){
                    if(errno != EAGAIN){
                        close(connfd);
                        users[fds[i].fd] = users[fds[user_counter].fd];
                        fds[i] = fds[user_counter];
                        i--;
                        user_counter--;
                    }
                }
                else if(ret == 0){}
                else{
                    for(int j = 1; j <= user_counter; ++j){
                        if(fds[j].fd == connfd)continue;

                        fds[j].events &= ~POLLIN;
                        fds[j].events |= POLLOUT;
                        users[fds[j].fd].write_buf = users[connfd].buf;
                    }
                }
            }
            else if(fds[i].revents & POLLOUT){
                int connfd = fds[i].fd;
                if(!users[connfd].write_buf){
                    continue;
                }
                ret = send(connfd,users[connfd].write_buf,strlen(users[connfd].write_buf),0);
                users[connfd].write_buf = NULL;
                fds[i].events &= ~POLLOUT;
                fds[i].events |= POLLIN;
            }
        }
    }
    delete []users;
    close(listenfd);
    return 0;
}