【select&poll】

1.select客户端

#include 
#include 
#include 
#include 
#include 

#define PORT 9999
#define IP "192.168.125.216"

int main() {
    int cfd = socket(AF_INET,SOCK_STREAM,0);
    if (cfd == -1)
    {
        perror("socket");
        return -1;
    }
    struct sockaddr_in cin;
    cin.sin_family = AF_INET;
    cin.sin_port = htons(PORT);
    cin.sin_addr.s_addr = inet_addr(IP);

    if (connect(cfd,(struct sockaddr*)&cin,sizeof(cin)) == -1)
    {
        perror("connect");
        return -1;
    }

    fd_set readfds;
    FD_ZERO(&readfds);
    FD_SET(0,&readfds);
    FD_SET(cfd,&readfds);

    while (1)
    {
        fd_set tempfds = readfds;
        int res = select(cfd+1,&tempfds,NULL,NULL,NULL);
        if (res == -1)
        {
            perror("select");
            return -1;
        }else if (res == 0)
        {
            printf("timeout\n");
        }
        

        if (FD_ISSET(0,&tempfds))
        {
            char buf[128];
            fgets(buf,sizeof(buf),stdin);
            buf[strlen(buf) -1] = 0;
            if (send(cfd,buf,sizeof(buf),0) == -1 )
            {
                perror("send");
                return -1;
            }

            if (strcmp(buf,"exit") == 0)
            {
                break;
            }
        }

        if (FD_ISSET(cfd,&tempfds))
        {
            char buf[128];
            int res = recv(cfd,buf,sizeof(buf),0);
            if (res == 0)
            {
                printf("服务器已下线\n");
                break;
            }
            printf("%s\n",buf);
            
        }
    }
    return 0;
}

2.poll服务器

#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define PORT 9999
#define MAX_CLIENTS 10

int main() {
    int sfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sfd == -1) {
        perror("socket");
        return -1;
    }

    struct sockaddr_in sin;
    sin.sin_family = AF_INET;
    sin.sin_port = htons(PORT);
    sin.sin_addr.s_addr = INADDR_ANY;

    if (bind(sfd, (struct sockaddr*)&sin, sizeof(sin)) == -1) {
        perror("bind");
        close(sfd);
        return -1;
    }

    if (listen(sfd, MAX_CLIENTS) == -1) {
        perror("listen");
        close(sfd);
        return -1;
    }

    struct pollfd fds[MAX_CLIENTS + 1];
    memset(fds, 0, sizeof(fds));

    fds[0].fd = sfd;
    fds[0].events = POLLIN;

    int nfds = 1;  // 当前监视的文件描述符数量

    printf("Server is listening on port %d...\n", PORT);

    while (1) {
        int numReady = poll(fds, nfds, -1);
        if (numReady == -1) {
            perror("poll");
            break;
        }

        // 处理监听套接字的事件
        if (fds[0].revents & POLLIN) {
            int cfd = accept(sfd, NULL, NULL);
            if (cfd == -1) {
                perror("accept");
            } else {
                printf("New client connected\n");
                fds[nfds].fd = cfd;
                fds[nfds].events = POLLIN;
                nfds++;
            }
            numReady--;
        }

        // 处理已连接套接字的事件
        for (int i = 1; i < nfds && numReady > 0; i++) {
            if (fds[i].revents & POLLIN) {
                char buf[128];
                int bytesRead = recv(fds[i].fd, buf, sizeof(buf) - 1, 0);
                if (bytesRead <= 0) {
                    if (bytesRead == 0) {
                        printf("Client disconnected\n");
                    } else {
                        perror("recv");
                    }
                    close(fds[i].fd);
                    // 将该套接字从监视列表中移除
                    fds[i] = fds[nfds - 1];
                    nfds--;
                } else {
                    buf[bytesRead] = '\0';
                    printf("Received from client: %s\n", buf);
                }
                numReady--;
            }
        }
    }

    // 关闭监听套接字
    close(sfd);

    return 0;
}