+
+#ifdef MULTICAST
+/*
+ * Set the IP multicast options in response to user setsockopt().
+ */
+int
+ip_setmoptions(optname, imop, m)
+ int optname;
+ struct ip_moptions **imop;
+ struct mbuf *m;
+{
+ register int error = 0;
+ u_char loop;
+ register int i;
+ struct in_addr addr;
+ register struct ip_mreq *mreq;
+ register struct ifnet *ifp;
+ register struct ip_moptions *imo = *imop;
+ struct route ro;
+ register struct sockaddr_in *dst;
+
+ if (imo == NULL) {
+ /*
+ * No multicast option buffer attached to the pcb;
+ * allocate one and initialize to default values.
+ */
+ imo = (struct ip_moptions*)malloc(sizeof(*imo), M_IPMOPTS,
+ M_WAITOK);
+
+ if (imo == NULL)
+ return (ENOBUFS);
+ *imop = imo;
+ imo->imo_multicast_ifp = NULL;
+ imo->imo_multicast_ttl = IP_DEFAULT_MULTICAST_TTL;
+ imo->imo_multicast_loop = IP_DEFAULT_MULTICAST_LOOP;
+ imo->imo_num_memberships = 0;
+ }
+
+ switch (optname) {
+
+ case IP_MULTICAST_IF:
+ /*
+ * Select the interface for outgoing multicast packets.
+ */
+ if (m == NULL || m->m_len != sizeof(struct in_addr)) {
+ error = EINVAL;
+ break;
+ }
+ addr = *(mtod(m, struct in_addr *));
+ /*
+ * INADDR_ANY is used to remove a previous selection.
+ * When no interface is selected, a default one is
+ * chosen every time a multicast packet is sent.
+ */
+ if (addr.s_addr == INADDR_ANY) {
+ imo->imo_multicast_ifp = NULL;
+ break;
+ }
+ /*
+ * The selected interface is identified by its local
+ * IP address. Find the interface and confirm that
+ * it supports multicasting.
+ */
+ INADDR_TO_IFP(addr, ifp);
+ if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0) {
+ error = EADDRNOTAVAIL;
+ break;
+ }
+ imo->imo_multicast_ifp = ifp;
+ break;
+
+ case IP_MULTICAST_TTL:
+ /*
+ * Set the IP time-to-live for outgoing multicast packets.
+ */
+ if (m == NULL || m->m_len != 1) {
+ error = EINVAL;
+ break;
+ }
+ imo->imo_multicast_ttl = *(mtod(m, u_char *));
+ break;
+
+ case IP_MULTICAST_LOOP:
+ /*
+ * Set the loopback flag for outgoing multicast packets.
+ * Must be zero or one.
+ */
+ if (m == NULL || m->m_len != 1 ||
+ (loop = *(mtod(m, u_char *))) > 1) {
+ error = EINVAL;
+ break;
+ }
+ imo->imo_multicast_loop = loop;
+ break;
+
+ case IP_ADD_MEMBERSHIP:
+ /*
+ * Add a multicast group membership.
+ * Group must be a valid IP multicast address.
+ */
+ if (m == NULL || m->m_len != sizeof(struct ip_mreq)) {
+ error = EINVAL;
+ break;
+ }
+ mreq = mtod(m, struct ip_mreq *);
+ if (!IN_MULTICAST(ntohl(mreq->imr_multiaddr.s_addr))) {
+ error = EINVAL;
+ break;
+ }
+ /*
+ * If no interface address was provided, use the interface of
+ * the route to the given multicast address.
+ */
+ if (mreq->imr_interface.s_addr == INADDR_ANY) {
+ ro.ro_rt = NULL;
+ dst = (struct sockaddr_in *)&ro.ro_dst;
+ dst->sin_len = sizeof(*dst);
+ dst->sin_family = AF_INET;
+ dst->sin_addr = mreq->imr_multiaddr;
+ rtalloc(&ro);
+ if (ro.ro_rt == NULL) {
+ error = EADDRNOTAVAIL;
+ break;
+ }
+ ifp = ro.ro_rt->rt_ifp;
+ rtfree(ro.ro_rt);
+ }
+ else {
+ INADDR_TO_IFP(mreq->imr_interface, ifp);
+ }
+ /*
+ * See if we found an interface, and confirm that it
+ * supports multicast.
+ */
+ if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0) {
+ error = EADDRNOTAVAIL;
+ break;
+ }
+ /*
+ * See if the membership already exists or if all the
+ * membership slots are full.
+ */
+ for (i = 0; i < imo->imo_num_memberships; ++i) {
+ if (imo->imo_membership[i]->inm_ifp == ifp &&
+ imo->imo_membership[i]->inm_addr.s_addr
+ == mreq->imr_multiaddr.s_addr)
+ break;
+ }
+ if (i < imo->imo_num_memberships) {
+ error = EADDRINUSE;
+ break;
+ }
+ if (i == IP_MAX_MEMBERSHIPS) {
+ error = ETOOMANYREFS;
+ break;
+ }
+ /*
+ * Everything looks good; add a new record to the multicast
+ * address list for the given interface.
+ */
+ if ((imo->imo_membership[i] =
+ in_addmulti(&mreq->imr_multiaddr, ifp)) == NULL) {
+ error = ENOBUFS;
+ break;
+ }
+ ++imo->imo_num_memberships;
+ break;
+
+ case IP_DROP_MEMBERSHIP:
+ /*
+ * Drop a multicast group membership.
+ * Group must be a valid IP multicast address.
+ */
+ if (m == NULL || m->m_len != sizeof(struct ip_mreq)) {
+ error = EINVAL;
+ break;
+ }
+ mreq = mtod(m, struct ip_mreq *);
+ if (!IN_MULTICAST(ntohl(mreq->imr_multiaddr.s_addr))) {
+ error = EINVAL;
+ break;
+ }
+ /*
+ * If an interface address was specified, get a pointer
+ * to its ifnet structure.
+ */
+ if (mreq->imr_interface.s_addr == INADDR_ANY)
+ ifp = NULL;
+ else {
+ INADDR_TO_IFP(mreq->imr_interface, ifp);
+ if (ifp == NULL) {
+ error = EADDRNOTAVAIL;
+ break;
+ }
+ }
+ /*
+ * Find the membership in the membership array.
+ */
+ for (i = 0; i < imo->imo_num_memberships; ++i) {
+ if ((ifp == NULL ||
+ imo->imo_membership[i]->inm_ifp == ifp) &&
+ imo->imo_membership[i]->inm_addr.s_addr ==
+ mreq->imr_multiaddr.s_addr)
+ break;
+ }
+ if (i == imo->imo_num_memberships) {
+ error = EADDRNOTAVAIL;
+ break;
+ }
+ /*
+ * Give up the multicast address record to which the
+ * membership points.
+ */
+ in_delmulti(imo->imo_membership[i]);
+ /*
+ * Remove the gap in the membership array.
+ */
+ for (++i; i < imo->imo_num_memberships; ++i)
+ imo->imo_membership[i-1] = imo->imo_membership[i];
+ --imo->imo_num_memberships;
+ break;
+
+ default:
+ error = EOPNOTSUPP;
+ break;
+ }
+
+ /*
+ * If all options have default values, no need to keep the mbuf.
+ */
+ if (imo->imo_multicast_ifp == NULL &&
+ imo->imo_multicast_ttl == IP_DEFAULT_MULTICAST_TTL &&
+ imo->imo_multicast_loop == IP_DEFAULT_MULTICAST_LOOP &&
+ imo->imo_num_memberships == 0) {
+ free(*imop, M_IPMOPTS);
+ *imop = NULL;
+ }
+
+ return (error);
+}
+
+/*
+ * Return the IP multicast options in response to user getsockopt().
+ */
+int
+ip_getmoptions(optname, imo, mp)
+ int optname;
+ register struct ip_moptions *imo;
+ register struct mbuf **mp;
+{
+ u_char *ttl;
+ u_char *loop;
+ struct in_addr *addr;
+ struct in_ifaddr *ia;
+
+ *mp = m_get(M_WAIT, MT_SOOPTS);
+
+ switch (optname) {
+
+ case IP_MULTICAST_IF:
+ addr = mtod(*mp, struct in_addr *);
+ (*mp)->m_len = sizeof(struct in_addr);
+ if (imo == NULL || imo->imo_multicast_ifp == NULL)
+ addr->s_addr = INADDR_ANY;
+ else {
+ IFP_TO_IA(imo->imo_multicast_ifp, ia);
+ addr->s_addr = (ia == NULL) ? INADDR_ANY
+ : IA_SIN(ia)->sin_addr.s_addr;
+ }
+ return (0);
+
+ case IP_MULTICAST_TTL:
+ ttl = mtod(*mp, u_char *);
+ (*mp)->m_len = 1;
+ *ttl = (imo == NULL) ? IP_DEFAULT_MULTICAST_TTL
+ : imo->imo_multicast_ttl;
+ return (0);
+
+ case IP_MULTICAST_LOOP:
+ loop = mtod(*mp, u_char *);
+ (*mp)->m_len = 1;
+ *loop = (imo == NULL) ? IP_DEFAULT_MULTICAST_LOOP
+ : imo->imo_multicast_loop;
+ return (0);
+
+ default:
+ return (EOPNOTSUPP);
+ }
+}
+
+/*
+ * Discard the IP multicast options.
+ */
+void
+ip_freemoptions(imo)
+ register struct ip_moptions *imo;
+{
+ register int i;
+
+ if (imo != NULL) {
+ for (i = 0; i < imo->imo_num_memberships; ++i)
+ in_delmulti(imo->imo_membership[i]);
+ free(imo, M_IPMOPTS);
+ }
+}
+
+/*
+ * Routine called from ip_output() to loop back a copy of an IP multicast
+ * packet to the input queue of a specified interface. Note that this
+ * calls the output routine of the loopback "driver", but with an interface
+ * pointer that might NOT be &loif -- easier than replicating that code here.
+ */
+static void
+ip_mloopback(ifp, m, dst)
+ struct ifnet *ifp;
+ register struct mbuf *m;
+ register struct sockaddr_in *dst;
+{
+ register struct ip *ip;
+ struct mbuf *copym;
+
+ copym = m_copy(m, 0, M_COPYALL);
+ if (copym != NULL) {
+ /*
+ * We don't bother to fragment if the IP length is greater
+ * than the interface's MTU. Can this possibly matter?
+ */
+ ip = mtod(copym, struct ip *);
+ ip->ip_len = htons((u_short)ip->ip_len);
+ ip->ip_off = htons((u_short)ip->ip_off);
+ ip->ip_sum = 0;
+ ip->ip_sum = in_cksum(copym, ip->ip_hl << 2);
+ (void) looutput(ifp, copym, (struct sockaddr *)dst);
+ }
+}
+#endif
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