C++ Udp Broadcast empfangen und antworten

void * udpbroadcast(void * param){

  sockaddr_in si_me, si_other;

  int s;

  assert((s=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP))!=-1);

  int port=6000;

  int broadcast=1;

  std::string recv;

  char *ip;

  setsockopt(s, SOL_SOCKET, SO_BROADCAST,

              &broadcast, sizeof broadcast);

  memset(&si_me, 0, sizeof(si_me));

  si_me.sin_family = AF_INET;

  si_me.sin_port = htons(port);

  si_me.sin_addr.s_addr = INADDR_ANY;

  assert(::bind(s, (sockaddr *)&si_me, sizeof(sockaddr))!=-1);

  while(1)

  {

      char buf[10000];

      unsigned slen=sizeof(sockaddr);

      recvfrom(s, buf, sizeof(buf)-1, 0, (sockaddr *)&si_other, &slen);

      recv = buf;

      ip = inet_ntoa(si_other.sin_addr);

      if(recv.compare("HELLO DEVICE") == 0){

        std::cout << "UDP Broadcast from: " << ip << "\n";

        //Antwort

      }

  }

}