keepalive心跳包

static int setup_ip_heartbeat(int fd)
{
    int ret = -1;
    // open keepalive on fd
    int alive = 1;
    ret = setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &alive, sizeof(alive));
    if(ret < 0) {
        perror("setsockopt:");
        return -1;
    }

    // 60s no socket data, send heartbeat package
    int idle = 60;
    ret = setsockopt(fd, SOL_TCP, TCP_KEEPIDLE, &idle, sizeof(idle));
    if(ret < 0) {
        perror("setsockopt:");
        return -1;
    }

    // if without any respond, 30s later resend package
    int intv = 3;
    ret = setsockopt(fd, SOL_TCP, TCP_KEEPINTVL, &intv, sizeof(intv));
    if(ret < 0) {
        perror("setsockopt:");
        return -1;
    }
    
    //try to send 3 times, without any response,mean connect lose
    int cnt = 1;
    ret = setsockopt(fd, SOL_TCP, TCP_KEEPCNT, &cnt, sizeof(cnt));
    if(ret < 0) {
        perror("setsocket:");
        return -1;
    }

}

#include <netinet/tcp.h>
#include <sys/socket.h>