select同时处理普通数据及带外数据

古城微笑少年丶 2022-07-26 00:16 140阅读 0赞

select系统调用，同时处理普通数据及带外数据程序源码：

#include <sys/types.h>
    #include <sys/socket.h>
    #include <arpa/inet.h>
    #include <netinet/in.h>
    #incldue <assert.h>
    #include <stdio.h>
    #include <unistd.h>
    #include <errno.h>
    #include <string.h>
    #include <fcntl.h>
    #include <stdlib.h>
    
    int main(int argc, char* argv[])
    {
        if(argc <= 2){
            printf("args err");
            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);
    
        int listenfd = socket(PF_INET, SOCK_STREAM, 0);
        assert(ret != -1);
        ret = listen(listenfd, 5);
        assert(ret != -1);
    
    
        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:%d", errno);
            close(listenfd);
        }
    
        char buf[1024];
        fd_set read_fds;
        fd_set exception_fds;
        FD_ZERO(&read_fds);
        FD_ZERO(&exception_fds);
    
        while(1)
        {
            memset(buf, '\0', sizeof(buf));
            /*
            *每次调用select前都要重新在read_fds和exception_fds中设置文件描述符connfd，
            *因为事件发生后，文件描述符集合将被内核修改。
            **/
            FD_SET(connfd, &read_fds);
            FD_SET(connfd, &exception_fds);
    
            ret = select(connfd+1, &read_fds, NULL, &exception_fds, NULL);
            if(ret < 0){
                printf("selection failure\n");
                break;
            }
    
            if(FD_ISSET(connfd, &read_fds))
            {
                //可读事件，采用普通recv函数读取数据
                ret = recv(connfd, buf, sizeof(buf)-1, 0);//最后一个参数为0
                if(ret < 0){
                    break;
                }
                printf("获取%d的数据:%s\n", ret, buf);
            }
            else if(FD_ISSET(connfd, &exception_fds))//
            {
                //异常事件，采用带MSG_OOB标志的recv函数读取带外数据
                ret = recv(connfd, buf, sizeof(buf)-1, MSG_OOB);//最后一个参数为MSG_OOB
                if(ret <= 0){
                    break;
                }
                printf("获取%d的数据:%s\n", ret, buf);
            }
        }
    
        close(connfd);
        close(listenfd);
    
        return 0;
    }

代码来自：《Linux高性能服务器编程》