Get UP/DOWN status of network interface in Linux

interfaceStatus.cc

#include <iostream>
#include <netinet/in.h>
#include <string.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <unistd.h>

int is_interface_online(std::string interface)
{
    int fd = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (fd < 0)
    {
        return -1;
    }

    struct ifreq ethreq;
    memset(&ethreq, 0, sizeof(ethreq));
    strncpy(ethreq.ifr_name, interface.c_str(), IFNAMSIZ);

    int res = ioctl(fd, SIOCGIFFLAGS, &ethreq);
    if (res < 0)
    {
        return res;
    }

    if (ethreq.ifr_flags & IFF_RUNNING)
    {
        close(fd);
        return 0;
    }
    close(fd);
    return 1;
}

int main(int argc, char *argv[])
{
    int result = is_interface_online(argv[1]);
    if (result == 0)
    {
        std::cout << "TRUE\n";
    }
    else
    {
        std::cout << "FALSE\n";
    }
    return 0;
}