+static void do_mgroup_join(int fd, int family, int socktype, int protocol, const char *mgroup)
+{
+ struct addrinfo hints, *res0, *res;
+ struct ip_mreq mreq;
+ struct ipv6_mreq m6req;
+ int gerr;
+
+ memset(&hints, 0, sizeof(hints));
+
+ hints.ai_flags |= AI_PASSIVE;
+ hints.ai_family = family;
+ hints.ai_socktype = socktype;
+ hints.ai_protocol = protocol;
+
+ if ((gerr = getaddrinfo(mgroup, NULL, &hints, &res0)) != 0) {
+ fprintf(stderr, "getaddrinfo(): %s\n", gai_strerror(gerr));
+ return;
+ }
+
+ for (res = res0; res; res = res->ai_next) {
+ if (AF_INET == family) {
+ memset(&mreq, 0, sizeof(mreq));
+ mreq.imr_multiaddr = ((struct sockaddr_in *)res->ai_addr)->sin_addr;
+ if (setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) == -1) {
+ fprintf(stderr, "setsockopt(IP_ADD_MEMBERSHIP): %s\n", strerror(errno));
+ continue;
+ }
+ break;
+ } else if (AF_INET6 == family) {
+ memset(&m6req, 0, sizeof(m6req));
+ m6req.ipv6mr_multiaddr = ((struct sockaddr_in6 *)res->ai_addr)->sin6_addr;
+ if (setsockopt(fd, IPPROTO_IPV6, IPV6_JOIN_GROUP, &m6req, sizeof(m6req)) == -1) {
+ fprintf(stderr, "setsockopt(IPV6_JOIN_GROUP): %s\n", strerror(errno));
+ continue;
+ }
+ break;
+ } else {
+ fprintf(stderr, "unknown family during multicast group bind!\n");
+ break;
+ }
+ }
+
+ freeaddrinfo(res0);
+}
+
+