pimd: fixup join desired handling to match the RFC defined macro

This commit includes the following changes -
1. kat needs to be included when evaluting join desired on a (S,G)
   entry.
2. there were cases where we were adding OIF based on joindesired
   being true for unrelated reasons (on other OIFs). cleaned up those
   cases.
3. make all calls to pim_upstream_switch conditional on the JoinDesired
   macro.

Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>

4 files changed, 126 insertions, 64 deletions

diff --git a/pimd/pim_ifchannel.c b/pimd/pim_ifchannel.c
index 77104dc81..ac53808af 100644
--- a/pimd/pim_ifchannel.c
+++ b/pimd/pim_ifchannel.c
@@ -252,6 +252,7 @@ void pim_ifchannel_ifjoin_switch(const char *caller, struct pim_ifchannel *ch,
 {
 	enum pim_ifjoin_state old_state = ch->ifjoin_state;
 	struct pim_interface *pim_ifp = ch->interface->info;
+	struct pim_ifchannel *child_ch;
 
 	if (PIM_DEBUG_PIM_EVENTS)
 		zlog_debug(
@@ -295,23 +296,12 @@ void pim_ifchannel_ifjoin_switch(const char *caller, struct pim_ifchannel *ch,
 					if (!c_oil)
 						continue;
 
-					if (!pim_upstream_evaluate_join_desired(
-						    pim_ifp->pim, child)) {
-						pim_channel_del_oif(
-							c_oil, ch->interface,
-							PIM_OIF_FLAG_PROTO_STAR,
-							__func__);
-						pim_upstream_update_join_desired(
-							pim_ifp->pim, child);
-					}
-
 					/*
 					 * If the S,G has no if channel and the
 					 * c_oil still
 					 * has output here then the *,G was
 					 * supplying the implied
 					 * if channel.  So remove it.
-					 * I think this is dead code now. is it?
 					 */
 					if (c_oil->oil.mfcc_ttls
 						    [pim_ifp->mroute_vif_index])
@@ -332,8 +322,14 @@ void pim_ifchannel_ifjoin_switch(const char *caller, struct pim_ifchannel *ch,
 							child->sg_str,
 							up->sg_str);
 
-					if (pim_upstream_evaluate_join_desired(
-						    pim_ifp->pim, child)) {
+					/* check if the channel can be
+					 * inherited into the SG's OIL
+					 */
+					child_ch = pim_ifchannel_find(
+							ch->interface,
+							&child->sg);
+					if (pim_upstream_eval_inherit_if(
+						    child, child_ch, ch)) {
 						pim_channel_add_oif(
 							child->channel_oil,
 							ch->interface,
@@ -905,14 +901,18 @@ void pim_ifchannel_join_add(struct interface *ifp, struct in_addr neigh_addr,
 			pim_ifchannel_ifjoin_switch(__PRETTY_FUNCTION__, ch,
 						    PIM_IFJOIN_JOIN);
 			PIM_IF_FLAG_UNSET_S_G_RPT(ch->flags);
-			if (pim_upstream_evaluate_join_desired(pim_ifp->pim,
-							       ch->upstream)) {
+			/* check if the interface qualifies as an immediate
+			 * OIF
+			 */
+			if (pim_upstream_evaluate_join_desired_interface(
+						ch->upstream, ch,
+						NULL /*starch*/)) {
 				pim_channel_add_oif(ch->upstream->channel_oil,
-						    ch->interface,
-						    PIM_OIF_FLAG_PROTO_PIM,
-							__func__);
+						ch->interface,
+						PIM_OIF_FLAG_PROTO_PIM,
+						__func__);
 				pim_upstream_update_join_desired(pim_ifp->pim,
-								 ch->upstream);
+						ch->upstream);
 			}
 		}
 		break;
@@ -1113,8 +1113,7 @@ int pim_ifchannel_local_membership_add(struct interface *ifp,
 				pim_channel_add_oif(child->channel_oil, ifp,
 						    PIM_OIF_FLAG_PROTO_STAR,
 							__func__);
-				pim_upstream_switch(pim, child,
-						    PIM_UPSTREAM_JOINED);
+				pim_upstream_update_join_desired(pim, child);
 			}
 		}
 
@@ -1421,8 +1420,8 @@ void pim_ifchannel_set_star_g_join_state(struct pim_ifchannel *ch, int eom,
 					child->upstream->channel_oil,
 					ch->interface, PIM_OIF_FLAG_PROTO_STAR,
 					__func__);
-				pim_upstream_switch(pim, child->upstream,
-						    PIM_UPSTREAM_JOINED);
+				pim_upstream_update_join_desired(pim,
+						child->upstream);
 				pim_jp_agg_single_upstream_send(
 					&child->upstream->rpf, child->upstream,
 					true);
diff --git a/pimd/pim_mroute.c b/pimd/pim_mroute.c
index a2e6aabcf..7b8ea5f7f 100644
--- a/pimd/pim_mroute.c
+++ b/pimd/pim_mroute.c
@@ -277,8 +277,7 @@ static int pim_mroute_msg_wholepkt(int fd, struct interface *ifp,
 			pim_upstream_keep_alive_timer_start(
 				up, pim_ifp->pim->keep_alive_time);
 			pim_upstream_inherited_olist(pim_ifp->pim, up);
-			pim_upstream_switch(pim_ifp->pim, up,
-					    PIM_UPSTREAM_JOINED);
+			pim_upstream_update_join_desired(pim_ifp->pim, up);
 
 			if (PIM_DEBUG_MROUTE)
 				zlog_debug("%s: Creating %s upstream on LHR",
diff --git a/pimd/pim_upstream.c b/pimd/pim_upstream.c
index d841d10a0..c79e85cd0 100644
--- a/pimd/pim_upstream.c
+++ b/pimd/pim_upstream.c
@@ -952,6 +952,36 @@ struct pim_upstream *pim_upstream_add(struct pim_instance *pim,
 /*
  * Passed in up must be the upstream for ch.  starch is NULL if no
  * information
+ * This function is copied over from
+ * pim_upstream_evaluate_join_desired_interface but limited to
+ * parent (*,G)'s includes/joins.
+ */
+int pim_upstream_eval_inherit_if(struct pim_upstream *up,
+						 struct pim_ifchannel *ch,
+						 struct pim_ifchannel *starch)
+{
+	/* if there is an explicit prune for this interface we cannot
+	 * add it to the OIL
+	 */
+	if (ch) {
+		if (PIM_IF_FLAG_TEST_S_G_RPT(ch->flags))
+			return 0;
+	}
+
+	/* Check if the OIF can be inherited fron the (*,G) entry
+	 */
+	if (starch) {
+		if (!pim_macro_ch_lost_assert(starch)
+		    && pim_macro_chisin_joins_or_include(starch))
+			return 1;
+	}
+
+	return 0;
+}
+
+/*
+ * Passed in up must be the upstream for ch.  starch is NULL if no
+ * information
  */
 int pim_upstream_evaluate_join_desired_interface(struct pim_upstream *up,
 						 struct pim_ifchannel *ch,
@@ -970,8 +1000,14 @@ int pim_upstream_evaluate_join_desired_interface(struct pim_upstream *up,
 	 * joins (*,G)
 	 */
 	if (starch) {
+		/* XXX: check on this with donald
+		 * we are looking for PIM_IF_FLAG_MASK_S_G_RPT in
+		 * upstream flags?
+		 */
+#if 0
 		if (PIM_IF_FLAG_TEST_S_G_RPT(starch->upstream->flags))
 			return 0;
+#endif
 
 		if (!pim_macro_ch_lost_assert(starch)
 		    && pim_macro_chisin_joins_or_include(starch))
@@ -981,56 +1017,76 @@ int pim_upstream_evaluate_join_desired_interface(struct pim_upstream *up,
 	return 0;
 }
 
-/*
-  Evaluate JoinDesired(S,G):
-
-  JoinDesired(S,G) is true if there is a downstream (S,G) interface I
-  in the set:
-
-  inherited_olist(S,G) =
-  joins(S,G) (+) pim_include(S,G) (-) lost_assert(S,G)
-
-  JoinDesired(S,G) may be affected by changes in the following:
-
-  pim_ifp->primary_address
-  pim_ifp->pim_dr_addr
-  ch->ifassert_winner_metric
-  ch->ifassert_winner
-  ch->local_ifmembership
-  ch->ifjoin_state
-  ch->upstream->rpf.source_nexthop.mrib_metric_preference
-  ch->upstream->rpf.source_nexthop.mrib_route_metric
-  ch->upstream->rpf.source_nexthop.interface
-
-  See also pim_upstream_update_join_desired() below.
+/* Returns true if immediate OIL is empty and is used to evaluate
+ * JoinDesired. See pim_upstream_evaluate_join_desired.
  */
-int pim_upstream_evaluate_join_desired(struct pim_instance *pim,
+static bool pim_upstream_empty_immediate_olist(struct pim_instance *pim,
 				       struct pim_upstream *up)
 {
 	struct interface *ifp;
-	struct pim_ifchannel *ch, *starch;
-	struct pim_upstream *starup = up->parent;
-	int ret = 0;
+	struct pim_ifchannel *ch;
 
 	FOR_ALL_INTERFACES (pim->vrf, ifp) {
 		if (!ifp->info)
 			continue;
 
 		ch = pim_ifchannel_find(ifp, &up->sg);
-
-		if (starup)
-			starch = pim_ifchannel_find(ifp, &starup->sg);
-		else
-			starch = NULL;
-
-		if (!ch && !starch)
+		if (!ch)
 			continue;
 
-		ret += pim_upstream_evaluate_join_desired_interface(up, ch,
-								    starch);
+		/* If we have even one immediate OIF we can return with
+		 * not-empty
+		 */
+		if (pim_upstream_evaluate_join_desired_interface(up, ch,
+					    NULL /* starch */))
+			return false;
 	} /* scan iface channel list */
 
-	return ret; /* false */
+	/* immediate_oil is empty */
+	return true;
+}
+
+static bool pim_upstream_is_kat_running(struct pim_upstream *up)
+{
+	return (up->t_ka_timer != NULL);
+}
+
+/*
+ *   bool JoinDesired(*,G) {
+ *       if (immediate_olist(*,G) != NULL)
+ *           return TRUE
+ *       else
+ *           return FALSE
+ *   }
+ *
+ *   bool JoinDesired(S,G) {
+ *       return( immediate_olist(S,G) != NULL
+ *           OR ( KeepaliveTimer(S,G) is running
+ *           AND inherited_olist(S,G) != NULL ) )
+ *   }
+ */
+int pim_upstream_evaluate_join_desired(struct pim_instance *pim,
+				       struct pim_upstream *up)
+{
+	bool empty_imm_oil;
+	bool empty_inh_oil;
+
+	empty_imm_oil = pim_upstream_empty_immediate_olist(pim, up);
+
+	/* (*,G) */
+	if (up->sg.src.s_addr == INADDR_ANY)
+		return !empty_imm_oil;
+
+	/* (S,G) */
+	if (!empty_imm_oil)
+		return true;
+	empty_inh_oil = pim_upstream_empty_inherited_olist(up);
+	if (!empty_inh_oil &&
+			(pim_upstream_is_kat_running(up) ||
+			 I_am_RP(pim, up->sg.grp)))
+		return true;
+
+	return false;
 }
 
 /*
@@ -1257,6 +1313,9 @@ struct pim_upstream *pim_upstream_keep_alive_timer_proc(
 	/* source is no longer active - pull the SA from MSDP's cache */
 	pim_msdp_sa_local_del(pim, &up->sg);
 
+	/* JoinDesired can change when KAT is started or stopped */
+	pim_upstream_update_join_desired(pim, up);
+
 	/* if entry was created because of activity we need to deref it */
 	if (PIM_UPSTREAM_FLAG_TEST_SRC_STREAM(up->flags)) {
 		pim_upstream_fhr_kat_expiry(pim, up);
@@ -1319,6 +1378,8 @@ void pim_upstream_keep_alive_timer_start(struct pim_upstream *up, uint32_t time)
 	/* any time keepalive is started against a SG we will have to
 	 * re-evaluate our active source database */
 	pim_msdp_sa_local_update(up);
+	/* JoinDesired can change when KAT is started or stopped */
+	pim_upstream_update_join_desired(up->pim, up);
 }
 
 /* MSDP on RP needs to know if a source is registerable to this RP */
@@ -1669,9 +1730,9 @@ int pim_upstream_inherited_olist(struct pim_instance *pim,
 	 * switch on a stick so turn on forwarding to just accept the
 	 * incoming packets so we don't bother the other stuff!
 	 */
-	if (output_intf)
-		pim_upstream_switch(pim, up, PIM_UPSTREAM_JOINED);
-	else
+	pim_upstream_update_join_desired(pim, up);
+
+	if (!output_intf)
 		forward_on(up);
 
 	return output_intf;
diff --git a/pimd/pim_upstream.h b/pimd/pim_upstream.h
index 3925bdf4a..815896a7d 100644
--- a/pimd/pim_upstream.h
+++ b/pimd/pim_upstream.h
@@ -262,6 +262,9 @@ int pim_upstream_evaluate_join_desired(struct pim_instance *pim,
 int pim_upstream_evaluate_join_desired_interface(struct pim_upstream *up,
 						 struct pim_ifchannel *ch,
 						 struct pim_ifchannel *starch);
+int pim_upstream_eval_inherit_if(struct pim_upstream *up,
+						 struct pim_ifchannel *ch,
+						 struct pim_ifchannel *starch);
 void pim_upstream_update_join_desired(struct pim_instance *pim,
 				      struct pim_upstream *up);