[Live-devel] multicast & linux information

[PROMONET Michel]

            Hi Ross,

We discussed several times about this subject and I would like to share what I understood from exchanges with RedHat support.

It seems that kernel maintainers chose to keep the backward compatibility with a default that cause receiving data from all multicast groups and not only from joined multicast group.
But they add since kernel 2.6.31 an option that allow to avoid this.

In a test program, I tryied adding
#if defined(__linux__) && !defined(IP_MULTICAST_ALL)
            #warning linux is not able to filter multicast group that share same port without IP_MULTICAST_ALL option
#endif
#ifdef IP_MULTICAST_ALL
  int mc_all = 0;
  if ((setsockopt(sock, IPPROTO_IP, IP_MULTICAST_ALL,  (void*) &mc_all, sizeof(mc_all))) < 0) {
    perror("setsockopt() failed");
    exit(1);
  }
#endif
After this, multicast filter works "normally" (like windows & FreeBSD)

Do you think it could be possible to set this option in socketJoinGroup in a future release of live555 ?

Best Regards,

            Michel.


[@@ THALES GROUP INTERNAL @@]

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