Function carp_multicast_setup

freebsd/netinet/ip_carp.c:1376–1471

* Setup multicast structures. */

 * Setup multicast structures.
 */
static int
carp_multicast_setup(struct carp_if *cif, sa_family_t sa)
{
	struct ifnet *ifp = cif->cif_ifp;
	int error = 0;

	switch (sa) {
#ifdef INET
	case AF_INET:
	    {
		struct ip_moptions *imo = &cif->cif_imo;
		struct in_mfilter *imf;
		struct in_addr addr;

		if (ip_mfilter_first(&imo->imo_head) != NULL)
			return (0);

		imf = ip_mfilter_alloc(M_WAITOK, 0, 0);
		ip_mfilter_init(&imo->imo_head);
		imo->imo_multicast_vif = -1;

		addr.s_addr = htonl(INADDR_CARP_GROUP);
		if ((error = in_joingroup(ifp, &addr, NULL,
		    &imf->imf_inm)) != 0) {
			ip_mfilter_free(imf);
			break;
		}

		ip_mfilter_insert(&imo->imo_head, imf);
		imo->imo_multicast_ifp = ifp;
		imo->imo_multicast_ttl = CARP_DFLTTL;
		imo->imo_multicast_loop = 0;
		break;
	   }
#endif
#ifdef INET6
	case AF_INET6:
	    {
		struct ip6_moptions *im6o = &cif->cif_im6o;
		struct in6_mfilter *im6f[2];
		struct in6_addr in6;

		if (ip6_mfilter_first(&im6o->im6o_head))
			return (0);

		im6f[0] = ip6_mfilter_alloc(M_WAITOK, 0, 0);
		im6f[1] = ip6_mfilter_alloc(M_WAITOK, 0, 0);

		ip6_mfilter_init(&im6o->im6o_head);
		im6o->im6o_multicast_hlim = CARP_DFLTTL;
		im6o->im6o_multicast_ifp = ifp;

		/* Join IPv6 CARP multicast group. */
		bzero(&in6, sizeof(in6));
		in6.s6_addr16[0] = htons(0xff02);
		in6.s6_addr8[15] = 0x12;
		if ((error = in6_setscope(&in6, ifp, NULL)) != 0) {
			ip6_mfilter_free(im6f[0]);