+
+ if (multicast_iface_index != -1) {
+ ip_mreqn mr;
+ memset(&mr, 0, sizeof(mr));
+ mr.imr_ifindex = multicast_iface_index;
+ if (setsockopt(sock, IPPROTO_IP, IP_MULTICAST_IF, &mr, sizeof(mr)) == -1) {
+ log_perror("setsockopt(IP_MULTICAST_IF)");
+ }
+ if (setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_IF, &multicast_iface_index, sizeof(multicast_iface_index)) == -1) {
+ log_perror("setsockopt(IPV6_MULTICAST_IF)");
+ }
+ }