IO复用之select

 
#include <sys/select.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
int select(int nfds, fd_set *readfds, fd_set *writefds,
fd_set *exceptfds, struct timeval *timeout);

参数：
nfds：最大文件描述符+1
readfds：读文件描述符集合，可设置为NULL
writefds：写文件描述符集合，可设置为NULL
exceptfds：异常文件描述符集合，可设置为NULL
timeout：超时时间，设置为NULL为阻塞模式
返回值：
成功：返回检测到的文件描述符数量
失败：返回-1，设置errno
超时：返回0

 
#include <sys/select.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
//设置fd对应位图位置为0
void FD_CLR(int fd, fd_set *set);
//判断fd对应位图位置是否为1
int FD_ISSET(int fd, fd_set *set);
//设置fd对应位图位置为1
void FD_SET(int fd, fd_set *set);
//整个位图清零
void FD_ZERO(fd_set *set);

 
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/select.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define LISTEN_BACKLOG (5)
#define BUF_SIZE (1500)
#define ACK_STR "ack ok"
void usage(void) {
    printf("*********************************\n");
    printf("./server 本端ip 本端端口\n");
    printf("*********************************\n");
}
int main(int argc, char *argv[]){
    struct sockaddr_in local;
    struct sockaddr_in peer;
    int sock_fd = 0, new_fd = 0;
    int ret = 0;
    socklen_t addrlen = 0;
    char send_buf[BUF_SIZE] = {0};
    char recv_buf[BUF_SIZE] = {0};
    if (argc != 3) {
        usage();
        return -1;
    }
    char *ip = argv[1];
    unsigned short port = atoi(argv[2]);
    printf("ip:port->%s:%u\n", argv[1], port);
    sock_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (sock_fd == -1) {
        perror("socket error");
        return -1;
    }
    memset(&local, 0, sizeof(struct sockaddr_in));
    local.sin_family = AF_INET;
    local.sin_addr.s_addr = inet_addr(ip);
    local.sin_port = htons(port);
    ret = bind(sock_fd, (struct sockaddr *)&local, sizeof(struct sockaddr));
    if (ret == -1) {
        close(sock_fd);
        perror("bind error");
        return -1;
    }
    ret = listen(sock_fd, LISTEN_BACKLOG);
    if (ret == -1) {
        close(sock_fd);
        perror("listen error");
        return -1;
    }
    fd_set rfds;
    fd_set rfds_storage;
    FD_ZERO(&rfds_storage);
    FD_SET(sock_fd, &rfds_storage);
    int max_fd = sock_fd;
    while (1) {
        rfds = rfds_storage;
        struct  timeval tv = {.tv_sec = 5, .tv_usec = 0};
        ret = select(max_fd + 1, &rfds, NULL, NULL, &tv);
        if (ret == -1) {
            perror("select error");
            break;
        } else if (ret == 0) {
            printf("select timeout\n");
            continue;
        } else {
            printf("select ok\n");
        }
        for (int fd = 0; fd < max_fd + 1; fd++) {
            if (FD_ISSET(fd, &rfds)) {
                if (fd == sock_fd) {
                    addrlen = sizeof(peer);
                    new_fd = accept(sock_fd, (struct sockaddr *)&peer, &addrlen);
                    if (new_fd == -1) {
                        perror("accept error");
                        continue;
                    }
                    FD_SET(new_fd, &rfds_storage);
                    max_fd = (new_fd <= max_fd) ? max_fd : new_fd;
                    printf("accept success new fd:%d\n", new_fd);
                } else {
                    memset(recv_buf, 0, BUF_SIZE);
                    ret = recv(fd, recv_buf, BUF_SIZE, 0);
                    if (ret <= 0) {
                        close(fd);
                        FD_CLR(fd, &rfds_storage);
                    } else {
                        printf("recv len:%d, %s\n", ret, recv_buf);
                    }
                }
            }
        }
    }
    for (int fd = 0; fd < max_fd + 1; fd++) {
        if (FD_ISSET(fd, &rfds)) {
            printf("clsoe fd:%d\n", fd);
            close(fd);
        }
    }
    FD_ZERO(&rfds);
    FD_ZERO(&rfds_storage);
    return 0;
}

 
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define LISTEN_BACKLOG (5)
#define BUF_SIZE (1500)
#define REQUEST_STR "tcp pack"
void usage(void) {
    printf("*********************************\n");
    printf("./client 对端ip 对端端口\n");
    printf("*********************************\n");
}
int main(int argc, char *argv[]){
    struct sockaddr_in client;
    struct sockaddr_in server;
    int sock_fd = 0;
    int ret = 0;
    socklen_t addrlen = 0;
    char send_buf[BUF_SIZE] = {0};
    char recv_buf[BUF_SIZE] = {0};
    if (argc != 3) {
        usage();
        return -1;
    }
    char *ip = argv[1];
    unsigned short port = atoi(argv[2]);
    printf("ip:port->%s:%u\n", argv[1], port);
    sock_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (sock_fd == -1) {
        perror("socket error");
        return -1;
    }
    memset(&server, 0, sizeof(struct sockaddr_in));
    server.sin_family = AF_INET;
    server.sin_addr.s_addr = inet_addr(ip);
    server.sin_port = htons(port);
    ret = connect(sock_fd, (struct sockaddr *)&server,
sizeof(struct sockaddr));
    if (ret == -1) {
        close(sock_fd);
        perror("connect error");
        return -1;
    }
    int seq = 0;
    while(1) {
        memset(send_buf, 0, BUF_SIZE);
        sprintf(send_buf, "%s:%d", REQUEST_STR, seq++);
        send(sock_fd, send_buf, strlen(send_buf), 0);
        printf("send %s\n", send_buf);
        sleep(1);
    }
    close(sock_fd);
    return 0;
}