pimd: compute inherited_olist before checking for (S,G,rpt) prune decision

Problem description:
1) In some corner cases in PIM, incorrect (S,G,rpt) prunes were sent causing
   traffic blackholing to downstream receivers.
2) The inherited_olist emptiness check was performed before the list was
   computed due to lazy population of channel_oil, causing it to incorrectly
   appear empty and prune is incorrectly propogated.

Fix:
Ensure inherited_olist is computed before checking for emptiness during
(S,G,rpt) prune decision.

Signed-off-by: harini <[email protected]>

Author: hnattamaisub

pimd/pim_ifchannel.c

@@ -1039,6 +1039,8 @@ void pim_ifchannel_prune(struct interface *ifp, pim_addr upstream,
 				PIM_IF_FLAG_SET_S_G_RPT(ch->flags);
 
 			ch->ifjoin_state = PIM_IFJOIN_PRUNE_PENDING;
+			pim_upstream_inherited_olist_decide(pim_ifp->pim, ch->upstream);
+
 			if (listcount(pim_ifp->pim_neighbor_list) > 1)
 				jp_override_interval_msec =
 					pim_if_jp_override_interval_msec(ifp);

tests/topotests/pim_prune/__init__.py

@@ -0,0 +1 @@
+# SPDX-License-Identifier: ISC

tests/topotests/pim_prune/host11/frr.conf

@@ -0,0 +1,18 @@
+! -*- conf -*-
+!
+! Host11 Configuration (Source and Receiver host)
+! Note: host11 is NOT a PIM router - it just generates source traffic
+! and receives multicast via IGMP
+!
+interface lo
+ ip address 10.0.0.5/32
+!
+interface host11-eth0
+ ip address 10.0.14.5/24
+!
+interface host11-eth1
+ ip address 10.0.18.5/24
+ ip igmp
+!
+ip route 0.0.0.0/0 10.0.14.3
+!

tests/topotests/pim_prune/host_rp/frr.conf

@@ -0,0 +1,13 @@
+! -*- conf -*-
+!
+! host_rp Router Configuration (source on RP pod - like hd31 in SSIM)
+!
+interface lo
+ ip address 10.0.0.8/32
+!
+interface host_rp-eth0
+ ip address 10.0.20.8/24
+!
+! Static route to reach multicast network
+ip route 0.0.0.0/0 10.0.20.1
+!

tests/topotests/pim_prune/rp/frr.conf

@@ -0,0 +1,29 @@
+! -*- conf -*-
+!
+! RP Router Configuration
+!
+interface lo
+ ip address 10.0.0.1/32
+!
+interface rp-eth0
+ ip address 10.0.10.1/24
+ ip pim
+!
+interface rp-eth1
+ ip address 10.0.11.1/24
+ ip pim
+!
+! Interface to host_rp (source on RP pod - like hd31 in SSIM)
+interface rp-eth2
+ ip address 10.0.20.1/24
+ ip pim
+ ip igmp
+!
+router rip
+ network 10.0.0.0/8
+ redistribute connected
+!
+router pim
+ rp 10.0.0.1
+ join-prune-interval 60
+!

tests/topotests/pim_prune/spine1/frr.conf

@@ -0,0 +1,27 @@
+! -*- conf -*-
+!
+! Spine1 Router Configuration
+!
+interface lo
+ ip address 10.0.0.2/32
+!
+interface spine1-eth0
+ ip address 10.0.10.2/24
+ ip pim
+!
+interface spine1-eth1
+ ip address 10.0.12.2/24
+ ip pim
+!
+interface spine1-eth2
+ ip address 10.0.19.2/24
+ ip pim
+!
+router rip
+ network 10.0.0.0/8
+ redistribute connected
+!
+router pim
+ rp 10.0.0.1
+ join-prune-interval 60
+!

tests/topotests/pim_prune/spine2/frr.conf

@@ -0,0 +1,35 @@
+! -*- conf -*-
+!
+! Spine2 Router Configuration
+!
+interface lo
+ ip address 10.0.0.7/32
+!
+interface spine2-eth0
+ ip address 10.0.11.7/24
+ ip pim
+!
+interface spine2-eth1
+ ip address 10.0.16.7/24
+ ip pim
+!
+interface spine2-eth2
+ ip address 10.0.17.7/24
+ ip pim
+!
+! Access list to match source network
+access-list MATCH_SOURCE permit 10.0.14.0 0.0.0.255
+!
+router rip
+ network 10.0.0.0/8
+ redistribute connected
+ ! Make torc21 path less preferred for SOURCE routes
+ offset-list MATCH_SOURCE in 5 spine2-eth2
+ ! Make RP path less preferred for SOURCE routes
+ ! spine2 should learn source routes from torc11 directly (spine2-eth1), not via RP
+ offset-list MATCH_SOURCE in 5 spine2-eth0
+!
+router pim
+ rp 10.0.0.1
+ join-prune-interval 60
+!