Get MAC address on Linux

macaddr.cc

int getMacAddr(std::string ifname, char *macaddr) {
  // need to open a socket to read the mac address
  int sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
  if (sock == -1) {
    auto err = std::string(strerror(errno));
    return Status::UnknownError("failed to open socket" + err);
  }

  struct ifreq ifr;
  strcpy(ifr.ifr_name, ifname.c_str());
  int err = ioctl(sock, SIOCGIFHWADDR, &ifr);
  if (err != 0) {
    return err;
  }

  sprintf(macaddr, "%02x:%02x:%02x:%02x:%02x:%02x\0",
          ifr.ifr_addr.sa_data[0], ifr.ifr_addr.sa_data[1], ifr.ifr_addr.sa_data[2],
          ifr.ifr_addr.sa_data[3], ifr.ifr_addr.sa_data[4], ifr.ifr_addr.sa_data[5]);

  return 0;
}