pimd: Do not create upstream state when not DR for igmp request

When we receive a IGMP report on an interface, do not create upstream
state for that request, unless we are the DR for the incoming interface.

This will prevent a interface on a LAN segment from causing traffic
to flow to itself.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>

diff --git a/pimd/pim_zebra.c b/pimd/pim_zebra.c
index a58dfcdd5f0e5bc85e34b5f66b336fa3a15d1e7e..eddb4c7763cfa556faed6a6bef61be91291287c7 100644 (file)
--- a/pimd/pim_zebra.c
+++ b/pimd/pim_zebra.c
@@ -868,6 +868,7 @@ void igmp_source_forward_reevaluate_all(struct pim_instance *pim)
 void igmp_source_forward_start(struct pim_instance *pim,
                               struct igmp_source *source)
 {
+       struct pim_interface *pim_oif;
        struct igmp_group *group;
        struct prefix_sg sg;
        int result;
@@ -893,10 +894,20 @@ void igmp_source_forward_start(struct pim_instance *pim,
        }
 
        group = source->source_group;
+       pim_oif = group->group_igmp_sock->interface->info;
+       if (!pim_oif) {
+               if (PIM_DEBUG_IGMP_TRACE) {
+                       zlog_debug(
+                                  "%s: multicast not enabled on oif=%s ?",
+                                  __PRETTY_FUNCTION__,
+                                  source->source_group->group_igmp_sock
+                                  ->interface->name);
+               }
+               return;
+       }
 
        if (!source->source_channel_oil) {
                struct in_addr vif_source;
-               struct pim_interface *pim_oif;
                struct prefix nht_p, src, grp;
                struct pim_nexthop_cache out_pnc;
                struct pim_nexthop nexthop;
@@ -983,19 +994,6 @@ void igmp_source_forward_start(struct pim_instance *pim,
                  source and receiver attached to the same interface. See TODO
                  T22.
                */
-               pim_oif =
-                       source->source_group->group_igmp_sock->interface->info;
-               if (!pim_oif) {
-                       if (PIM_DEBUG_IGMP_TRACE) {
-                               zlog_debug(
-                                       "%s: multicast not enabled on oif=%s ?",
-                                       __PRETTY_FUNCTION__,
-                                       source->source_group->group_igmp_sock
-                                               ->interface->name);
-                       }
-                       return;
-               }
-
                if (input_iface_vif_index == pim_oif->mroute_vif_index) {
                        /* ignore request for looped MFC entry */
                        if (PIM_DEBUG_IGMP_TRACE) {
@@ -1036,12 +1034,15 @@ void igmp_source_forward_start(struct pim_instance *pim,
                return;
        }
 
+       if (!(PIM_I_am_DR(pim_oif)))
+               return;
+
        /*
          Feed IGMPv3-gathered local membership information into PIM
          per-interface (S,G) state.
         */
        if (!pim_ifchannel_local_membership_add(
-                   group->group_igmp_sock->interface, &sg)) {
+                                               group->group_igmp_sock->interface, &sg)) {
                if (PIM_DEBUG_MROUTE)
                        zlog_warn("%s: Failure to add local membership for %s",
                                  __PRETTY_FUNCTION__, pim_str_sg_dump(&sg));