pimd: Implement rpf lookup mode as a list

Add the support to store lookup modes as a sorted list.
List is non-unique and sorts mode with both lists < modes with one list < global mode (no lists).
This way, when finding the right mode, we will match a lookup using a prefix list before the global mode.
Add passing group address into all lookups (using nht cache and/or synchronous lookup).
Many areas don't have a group address, use PIMADDR_ANY if no valid group is needed.

Signed-off-by: Nathan Bahr <nbahr@atcorp.com>

10 files changed, 403 insertions, 93 deletions

diff --git a/pimd/pim_bsr_rpdb.c b/pimd/pim_bsr_rpdb.c
index 02e7a69ff..860009312 100644
--- a/pimd/pim_bsr_rpdb.c
+++ b/pimd/pim_bsr_rpdb.c
@@ -417,7 +417,7 @@ void pim_crp_nht_update(struct pim_instance *pim, struct pim_nexthop_cache *pnc)
 	rp = bsr_crp_rps_find(scope->ebsr_rps, &ref);
 	assertf(rp, "addr=%pPA", &ref.addr);
 
-	ok = pim_nht_pnc_is_valid(pim, pnc);
+	ok = pim_nht_pnc_is_valid(pim, pnc, PIMADDR_ANY);
 	if (ok == rp->nht_ok)
 		return;
 
diff --git a/pimd/pim_cmd.c b/pimd/pim_cmd.c
index 30baa6a2a..a1ad26186 100644
--- a/pimd/pim_cmd.c
+++ b/pimd/pim_cmd.c
@@ -3296,7 +3296,7 @@ DEFUN (show_ip_rib,
 		return CMD_WARNING;
 	}
 
-	if (!pim_nht_lookup(vrf->info, &nexthop, addr, 0)) {
+	if (!pim_nht_lookup(vrf->info, &nexthop, addr, PIMADDR_ANY, false)) {
 		vty_out(vty,
 			"Failure querying RIB nexthop for unicast address %s\n",
 			addr_str);
diff --git a/pimd/pim_igmp_mtrace.c b/pimd/pim_igmp_mtrace.c
index ad6f26510..f0fbb2bbf 100644
--- a/pimd/pim_igmp_mtrace.c
+++ b/pimd/pim_igmp_mtrace.c
@@ -59,7 +59,8 @@ static bool mtrace_fwd_info_weak(struct pim_instance *pim,
 
 	memset(&nexthop, 0, sizeof(nexthop));
 
-	if (!pim_nht_lookup(pim, &nexthop, mtracep->src_addr, 1)) {
+	/* TODO Is there any valid group address to use for lookup? */
+	if (!pim_nht_lookup(pim, &nexthop, mtracep->src_addr, PIMADDR_ANY, true)) {
 		if (PIM_DEBUG_MTRACE)
 			zlog_debug("mtrace not found neighbor");
 		return false;
@@ -354,7 +355,8 @@ static int mtrace_un_forward_packet(struct pim_instance *pim, struct ip *ip_hdr,
 
 	if (interface == NULL) {
 		memset(&nexthop, 0, sizeof(nexthop));
-		if (!pim_nht_lookup(pim, &nexthop, ip_hdr->ip_dst, 0)) {
+		/* TODO Is there any valid group address to use for lookup? */
+		if (!pim_nht_lookup(pim, &nexthop, ip_hdr->ip_dst, PIMADDR_ANY, false)) {
 			if (PIM_DEBUG_MTRACE)
 				zlog_debug(
 					"Dropping mtrace packet, no route to destination");
@@ -535,8 +537,11 @@ static int mtrace_send_response(struct pim_instance *pim,
 			zlog_debug("mtrace response to RP");
 	} else {
 		memset(&nexthop, 0, sizeof(nexthop));
-		/* TODO: should use unicast rib lookup */
-		if (!pim_nht_lookup(pim, &nexthop, mtracep->rsp_addr, 1)) {
+		/* TODO: should use unicast rib lookup
+		 *		NEB 10/30/24 - Not sure why this needs the unicast rib...right now it will look up per the rpf mode
+		 * Are any of the igmp_mtrace addresses a valid group address to use for lookups??
+		 */
+		if (!pim_nht_lookup(pim, &nexthop, mtracep->rsp_addr, PIMADDR_ANY, true)) {
 			if (PIM_DEBUG_MTRACE)
 				zlog_debug(
 					"Dropped response qid=%ud, no route to response address",
diff --git a/pimd/pim_instance.h b/pimd/pim_instance.h
index 7f022111b..7aa9d857d 100644
--- a/pimd/pim_instance.h
+++ b/pimd/pim_instance.h
@@ -18,6 +18,7 @@
 #include "pim_upstream.h"
 #include "pim_mroute.h"
 #include "pim_autorp.h"
+#include "pim_nht.h"
 
 enum pim_spt_switchover {
 	PIM_SPT_IMMEDIATE,
@@ -116,7 +117,7 @@ struct pim_instance {
 	char *register_plist;
 
 	struct hash *nht_hash;
-	enum pim_rpf_lookup_mode rpf_mode;
+	struct pim_lookup_mode_head rpf_mode;
 
 	void *ssm_info; /* per-vrf SSM configuration */
 
diff --git a/pimd/pim_mroute.c b/pimd/pim_mroute.c
index 93bdd8dac..6c13e1324 100644
--- a/pimd/pim_mroute.c
+++ b/pimd/pim_mroute.c
@@ -567,7 +567,8 @@ int pim_mroute_msg_wrvifwhole(int fd, struct interface *ifp, const char *buf,
 			 * setting the SPTBIT to true
 			 */
 			if (!(pim_addr_is_any(up->upstream_register)) &&
-			    pim_nht_lookup(pim_ifp->pim, &source, up->upstream_register, 0)) {
+			    pim_nht_lookup(pim_ifp->pim, &source, up->upstream_register, up->sg.grp,
+					   false)) {
 				pim_register_stop_send(source.interface, &sg,
 						       pim_ifp->primary_address,
 						       up->upstream_register);
@@ -580,7 +581,8 @@ int pim_mroute_msg_wrvifwhole(int fd, struct interface *ifp, const char *buf,
 							__func__);
 		} else {
 			if (I_am_RP(pim_ifp->pim, up->sg.grp)) {
-				if (pim_nht_lookup(pim_ifp->pim, &source, up->upstream_register, 0))
+				if (pim_nht_lookup(pim_ifp->pim, &source, up->upstream_register,
+						   up->sg.grp, false))
 					pim_register_stop_send(
 						source.interface, &sg,
 						pim_ifp->primary_address,
diff --git a/pimd/pim_msdp.c b/pimd/pim_msdp.c
index 5e5ee5e91..46d5f4881 100644
--- a/pimd/pim_msdp.c
+++ b/pimd/pim_msdp.c
@@ -706,7 +706,7 @@ bool pim_msdp_peer_rpf_check(struct pim_msdp_peer *mp, struct in_addr rp)
 	}
 
 	/* check if the MSDP peer is the nexthop for the RP */
-	if (pim_nht_lookup(mp->pim, &nexthop, rp, 0) &&
+	if (pim_nht_lookup(mp->pim, &nexthop, rp, PIMADDR_ANY, false) &&
 	    nexthop.mrib_nexthop_addr.s_addr == mp->peer.s_addr) {
 		return true;
 	}
diff --git a/pimd/pim_nht.c b/pimd/pim_nht.c
index 5830ca14b..1e9ea24b2 100644
--- a/pimd/pim_nht.c
+++ b/pimd/pim_nht.c
@@ -34,6 +34,176 @@
 #include "pim_register.h"
 #include "pim_vxlan.h"
 
+DEFINE_MTYPE_STATIC(PIMD, PIM_LOOKUP_MODE, "PIM RPF lookup mode");
+DEFINE_MTYPE_STATIC(PIMD, PIM_LOOKUP_MODE_STR, "PIM RPF lookup mode prefix list string");
+
+static void pim_update_rp_nh(struct pim_instance *pim, struct pim_nexthop_cache *pnc);
+static int pim_update_upstream_nh(struct pim_instance *pim, struct pim_nexthop_cache *pnc);
+
+static int pim_lookup_mode_cmp(const struct pim_lookup_mode *l, const struct pim_lookup_mode *r)
+{
+	/* Let's just sort anything with both lists set above those with only one list set,
+	 * which is above the global where neither are set
+	 */
+
+	/* Both are set on right, either lower or equal */
+	if (l->grp_plist != NULL && l->src_plist != NULL)
+		return (r->grp_plist == NULL || r->src_plist == NULL) ? -1 : 0;
+
+	/* Only one set on the left */
+	if (!(l->grp_plist == NULL && l->src_plist == NULL)) {
+		/* Lower only if both are not set on right */
+		if (r->grp_plist == NULL && r->src_plist == NULL)
+			return -1;
+		/* Higher only if both are set on right */
+		if (r->grp_plist != NULL && r->src_plist != NULL)
+			return 1;
+		/* Otherwise both sides have at least one set, so equal */
+		return 0;
+	}
+
+	/* Neither set on left, so equal if neither set on right also */
+	if (r->grp_plist == NULL && r->src_plist == NULL)
+		return 0;
+
+	/* Otherwise higher */
+	return 1;
+}
+
+DECLARE_SORTLIST_NONUNIQ(pim_lookup_mode, struct pim_lookup_mode, list, pim_lookup_mode_cmp);
+
+static void pim_lookup_mode_free(struct pim_lookup_mode *m)
+{
+	if (m->grp_plist)
+		XFREE(MTYPE_PIM_LOOKUP_MODE_STR, m->grp_plist);
+	if (m->src_plist)
+		XFREE(MTYPE_PIM_LOOKUP_MODE_STR, m->src_plist);
+	XFREE(MTYPE_PIM_LOOKUP_MODE, m);
+}
+
+static void pim_lookup_mode_list_free(struct pim_lookup_mode_head *head)
+{
+	struct pim_lookup_mode *m;
+
+	while ((m = pim_lookup_mode_pop(head)))
+		pim_lookup_mode_free(m);
+}
+
+enum pim_rpf_lookup_mode pim_get_lookup_mode(struct pim_instance *pim, pim_addr group,
+					     pim_addr source)
+{
+	struct pim_lookup_mode *m;
+	struct prefix_list *plist;
+	struct prefix p;
+
+	frr_each_safe (pim_lookup_mode, &(pim->rpf_mode), m) {
+		if (!pim_addr_is_any(group) && m->grp_plist) {
+			/* Match group against plist, continue if no match */
+			plist = prefix_list_lookup(PIM_AFI, m->grp_plist);
+			if (plist == NULL)
+				continue;
+			pim_addr_to_prefix(&p, group);
+			if (prefix_list_apply(plist, &p) == PREFIX_DENY)
+				continue;
+		}
+
+		if (!pim_addr_is_any(source) && m->src_plist) {
+			/* Match source against plist, continue if no match */
+			plist = prefix_list_lookup(PIM_AFI, m->src_plist);
+			if (plist == NULL)
+				continue;
+			pim_addr_to_prefix(&p, source);
+			if (prefix_list_apply(plist, &p) == PREFIX_DENY)
+				continue;
+		}
+
+		/* If lookup mode has a group list, but no group is provided, don't match it */
+		if (pim_addr_is_any(group) && m->grp_plist)
+			continue;
+
+		/* If lookup mode has a source list, but no source is provided, don't match it */
+		if (pim_addr_is_any(source) && m->src_plist)
+			continue;
+
+		/* Match found */
+		return m->mode;
+	}
+
+	/* This shouldn't happen since we have the global mode, but if it's gone,
+	 * just return the default of no config
+	 */
+	if (PIM_DEBUG_PIM_NHT)
+		zlog_debug("%s: No RPF lookup matched for given group %pPA and source %pPA",
+			   __func__, &group, &source);
+
+	return MCAST_NO_CONFIG;
+}
+
+static bool pim_rpf_mode_changed(enum pim_rpf_lookup_mode old, enum pim_rpf_lookup_mode new)
+{
+	if (old != new) {
+		/* These two are equivalent, so don't update in that case */
+		if (old == MCAST_NO_CONFIG && new == MCAST_MIX_MRIB_FIRST)
+			return false;
+		if (old == MCAST_MIX_MRIB_FIRST && new == MCAST_NO_CONFIG)
+			return false;
+		return true;
+	}
+	return false;
+}
+
+struct pnc_mode_update_hash_walk_data {
+	struct pim_instance *pim;
+	struct prefix_list *grp_plist;
+	struct prefix_list *src_plist;
+};
+
+static int pim_nht_hash_mode_update_helper(struct hash_bucket *bucket, void *arg)
+{
+	struct pim_nexthop_cache *pnc = bucket->data;
+	struct pnc_mode_update_hash_walk_data *pwd = arg;
+	struct pim_instance *pim = pwd->pim;
+	struct prefix p;
+
+	pim_addr_to_prefix(&p, pnc->addr);
+
+	/* Make sure this pnc entry matches the prefix lists */
+	/* TODO: For now, pnc only has the source address, so we can only check that */
+	if (pwd->src_plist &&
+	    (pim_addr_is_any(pnc->addr) || prefix_list_apply(pwd->src_plist, &p) == PREFIX_DENY))
+		return HASHWALK_CONTINUE;
+
+	/* Otherwise the address is any, or matches the prefix list, or no prefix list to match, so do the updates */
+	/* TODO for RP, there are groups....but I don't think we'd want to use those */
+	if (listcount(pnc->rp_list))
+		pim_update_rp_nh(pim, pnc);
+
+	/* TODO for upstream, there is an S,G key...can/should we use that group?? */
+	if (pnc->upstream_hash->count)
+		pim_update_upstream_nh(pim, pnc);
+
+	if (pnc->candrp_count)
+		pim_crp_nht_update(pim, pnc);
+
+	return HASHWALK_CONTINUE;
+}
+
+static void pim_rpf_mode_changed_update(struct pim_instance *pim, const char *group_plist,
+					const char *source_plist)
+{
+	struct pnc_mode_update_hash_walk_data pwd;
+
+	/* Update the refresh time to force new lookups if needed */
+	pim_rpf_set_refresh_time(pim);
+
+	/* Force update the registered RP and upstreams for all cache entries */
+	pwd.pim = pim;
+	pwd.grp_plist = prefix_list_lookup(PIM_AFI, group_plist);
+	pwd.src_plist = prefix_list_lookup(PIM_AFI, source_plist);
+
+	hash_walk(pim->nht_hash, pim_nht_hash_mode_update_helper, &pwd);
+}
+
 /**
  * pim_sendmsg_zebra_rnh -- Format and send a nexthop register/Unregister
  *   command to Zebra.
@@ -106,9 +276,10 @@ static struct pim_nexthop_cache *pim_nexthop_cache_add(struct pim_instance *pim,
 	return pnc;
 }
 
-static bool pim_nht_pnc_has_answer(struct pim_instance *pim, struct pim_nexthop_cache *pnc)
+static bool pim_nht_pnc_has_answer(struct pim_instance *pim, struct pim_nexthop_cache *pnc,
+				   pim_addr group)
 {
-	switch (pim->rpf_mode) {
+	switch (pim_get_lookup_mode(pim, group, pnc->addr)) {
 	case MCAST_MRIB_ONLY:
 		return CHECK_FLAG(pnc->mrib.flags, PIM_NEXTHOP_ANSWER_RECEIVED);
 
@@ -133,25 +304,28 @@ static bool pim_nht_pnc_has_answer(struct pim_instance *pim, struct pim_nexthop_
 }
 
 static struct pim_nexthop_cache_rib *pim_pnc_get_rib(struct pim_instance *pim,
-						     struct pim_nexthop_cache *pnc)
+						     struct pim_nexthop_cache *pnc, pim_addr group)
 {
 	struct pim_nexthop_cache_rib *pnc_rib = NULL;
+	enum pim_rpf_lookup_mode mode;
 
-	if (pim->rpf_mode == MCAST_MRIB_ONLY)
+	mode = pim_get_lookup_mode(pim, group, pnc->addr);
+
+	if (mode == MCAST_MRIB_ONLY)
 		pnc_rib = &pnc->mrib;
-	else if (pim->rpf_mode == MCAST_URIB_ONLY)
+	else if (mode == MCAST_URIB_ONLY)
 		pnc_rib = &pnc->urib;
-	else if (pim->rpf_mode == MCAST_MIX_MRIB_FIRST || pim->rpf_mode == MCAST_NO_CONFIG) {
+	else if (mode == MCAST_MIX_MRIB_FIRST || mode == MCAST_NO_CONFIG) {
 		if (pnc->mrib.nexthop_num > 0)
 			pnc_rib = &pnc->mrib;
 		else
 			pnc_rib = &pnc->urib;
-	} else if (pim->rpf_mode == MCAST_MIX_DISTANCE) {
+	} else if (mode == MCAST_MIX_DISTANCE) {
 		if (pnc->mrib.distance <= pnc->urib.distance)
 			pnc_rib = &pnc->mrib;
 		else
 			pnc_rib = &pnc->urib;
-	} else if (pim->rpf_mode == MCAST_MIX_PFXLEN) {
+	} else if (mode == MCAST_MIX_PFXLEN) {
 		if (pnc->mrib.prefix_len >= pnc->urib.prefix_len)
 			pnc_rib = &pnc->mrib;
 		else
@@ -161,23 +335,151 @@ static struct pim_nexthop_cache_rib *pim_pnc_get_rib(struct pim_instance *pim,
 	return pnc_rib;
 }
 
-
 void pim_nht_change_rpf_mode(struct pim_instance *pim, const char *group_plist,
 			     const char *source_plist, enum pim_rpf_lookup_mode mode)
 {
-	/* TODO */
-}
+	struct pim_lookup_mode *m;
+	bool found = false;
+	bool update = false;
+	const char *glist = NULL;
+	const char *slist = NULL;
+
+	/* Prefix lists may be passed in as empty string, leave them NULL instead */
+	if (group_plist && strlen(group_plist))
+		glist = group_plist;
+	if (source_plist && strlen(source_plist))
+		slist = source_plist;
+
+	frr_each_safe (pim_lookup_mode, &(pim->rpf_mode), m) {
+		if ((m->grp_plist && glist && strmatch(m->grp_plist, glist)) &&
+		    (m->src_plist && slist && strmatch(m->src_plist, slist))) {
+			/* Group and source plists are both set and matched */
+			found = true;
+			if (mode == MCAST_NO_CONFIG) {
+				/* MCAST_NO_CONFIG means we should remove this lookup mode
+				 * We don't know what other modes might match, or if only the global, so we need to
+				 * update all lookups
+				 */
+				pim_lookup_mode_del(&pim->rpf_mode, m);
+				pim_lookup_mode_free(m);
+				glist = NULL;
+				slist = NULL;
+				update = true;
+			} else {
+				/* Just changing mode */
+				update = pim_rpf_mode_changed(m->mode, mode);
+				m->mode = mode; /* Always make sure the mode is set, even if not updating */
+			}
+
+			if (update)
+				pim_rpf_mode_changed_update(pim, glist, slist);
+			break;
+		}
 
+		if ((m->grp_plist && glist && strmatch(m->grp_plist, glist)) &&
+		    (!m->src_plist && !slist)) {
+			/* Only group list set and matched */
+			found = true;
+			if (mode == MCAST_NO_CONFIG) {
+				/* MCAST_NO_CONFIG means we should remove this lookup mode
+				 * We don't know what other modes might match, or if only the global, so we need to
+				 * update all lookups
+				 */
+				pim_lookup_mode_del(&pim->rpf_mode, m);
+				pim_lookup_mode_free(m);
+				glist = NULL;
+				slist = NULL;
+				update = true;
+			} else {
+				/* Just changing mode */
+				update = pim_rpf_mode_changed(m->mode, mode);
+				m->mode = mode; /* Always make sure the mode is set, even if not updating */
+			}
+
+			if (update)
+				pim_rpf_mode_changed_update(pim, glist, slist);
+			break;
+		}
+
+		if ((!m->grp_plist && !glist) &&
+		    (m->src_plist && slist && strmatch(m->src_plist, slist))) {
+			/* Only source list set and matched */
+			found = true;
+			if (mode == MCAST_NO_CONFIG) {
+				/* MCAST_NO_CONFIG means we should remove this lookup mode
+				 * We don't know what other modes might match, or if only the global, so we need to
+				 * update all lookups
+				 */
+				pim_lookup_mode_del(&pim->rpf_mode, m);
+				pim_lookup_mode_free(m);
+				glist = NULL;
+				slist = NULL;
+				update = true;
+			} else {
+				/* Just changing mode */
+				update = pim_rpf_mode_changed(m->mode, mode);
+				m->mode = mode; /* Always make sure the mode is set, even if not updating */
+			}
+
+			if (update)
+				pim_rpf_mode_changed_update(pim, glist, slist);
+			break;
+		}
+
+		if (!m->grp_plist && !glist && !m->src_plist && !slist) {
+			/* No prefix lists set, so this is the global mode */
+			/* We never delete this mode, even when set back to MCAST_NO_CONFIG */
+			update = pim_rpf_mode_changed(m->mode, mode);
+			m->mode = mode; /* Always make sure the mode is set, even if not updating */
+			if (update)
+				pim_rpf_mode_changed_update(pim, glist, slist);
+			found = true;
+			break;
+		}
+	}
+
+	if (!found) {
+		/* Adding a new lookup mode with unique prefix lists, add it */
+		m = XCALLOC(MTYPE_PIM_LOOKUP_MODE, sizeof(struct pim_lookup_mode));
+		m->grp_plist = XSTRDUP(MTYPE_PIM_LOOKUP_MODE_STR, glist);
+		m->src_plist = XSTRDUP(MTYPE_PIM_LOOKUP_MODE_STR, slist);
+		m->mode = mode;
+		pim_lookup_mode_add(&(pim->rpf_mode), m);
+		pim_rpf_mode_changed_update(pim, glist, slist);
+	}
+}
 
 int pim_lookup_mode_write(struct pim_instance *pim, struct vty *vty)
 {
-	/* TODO */
-	return 0;
+	int writes = 0;
+	struct pim_lookup_mode *m;
+
+	frr_each_safe (pim_lookup_mode, &(pim->rpf_mode), m) {
+		if (m->mode == MCAST_NO_CONFIG)
+			continue;
+
+		++writes;
+		vty_out(vty, " rpf-lookup-mode %s",
+			m->mode == MCAST_URIB_ONLY	  ? "urib-only"
+			: m->mode == MCAST_MRIB_ONLY	  ? "mrib-only"
+			: m->mode == MCAST_MIX_MRIB_FIRST ? "mrib-then-urib"
+			: m->mode == MCAST_MIX_DISTANCE	  ? "lower-distance"
+							  : "longer-prefix");
+
+		if (m->grp_plist)
+			vty_out(vty, " group-list %s", m->grp_plist);
+
+		if (m->src_plist)
+			vty_out(vty, " source-list %s", m->src_plist);
+
+		vty_out(vty, "\n");
+	}
+	return writes;
 }
 
-bool pim_nht_pnc_is_valid(struct pim_instance *pim, struct pim_nexthop_cache *pnc)
+bool pim_nht_pnc_is_valid(struct pim_instance *pim, struct pim_nexthop_cache *pnc, pim_addr group)
 {
-	switch (pim->rpf_mode) {
+	switch (pim_get_lookup_mode(pim, group, pnc->addr)) {
 	case MCAST_MRIB_ONLY:
 		return CHECK_FLAG(pnc->mrib.flags, PIM_NEXTHOP_VALID);
 
@@ -289,6 +591,7 @@ bool pim_nht_find_or_track(struct pim_instance *pim, pim_addr addr, struct pim_u
 {
 	struct pim_nexthop_cache *pnc;
 	struct listnode *ch_node = NULL;
+	pim_addr group = PIMADDR_ANY;
 
 	/* This will find the entry and add it to tracking if not found */
 	pnc = pim_nht_get(pim, addr);
@@ -303,10 +606,12 @@ bool pim_nht_find_or_track(struct pim_instance *pim, pim_addr addr, struct pim_u
 	}
 
 	/* Store the upstream if provided and not currently in the list */
-	if (up != NULL)
+	if (up != NULL) {
 		(void)hash_get(pnc->upstream_hash, up, hash_alloc_intern);
+		group = up->sg.grp;
+	}
 
-	if (pim_nht_pnc_is_valid(pim, pnc)) {
+	if (pim_nht_pnc_is_valid(pim, pnc, group)) {
 		if (out_pnc)
 			memcpy(out_pnc, pnc, sizeof(struct pim_nexthop_cache));
 		return true;
@@ -329,7 +634,7 @@ bool pim_nht_candrp_add(struct pim_instance *pim, pim_addr addr)
 
 	pnc = pim_nht_get(pim, addr);
 	pnc->candrp_count++;
-	return pim_nht_pnc_is_valid(pim, pnc);
+	return pim_nht_pnc_is_valid(pim, pnc, PIMADDR_ANY);
 }
 
 static void pim_nht_drop_maybe(struct pim_instance *pim, struct pim_nexthop_cache *pnc)
@@ -462,7 +767,7 @@ bool pim_nht_bsr_rpf_check(struct pim_instance *pim, pim_addr bsr_addr,
 	lookup.addr = bsr_addr;
 
 	pnc = hash_lookup(pim->nht_hash, &lookup);
-	if (!pnc || !pim_nht_pnc_has_answer(pim, pnc)) {
+	if (!pnc || !pim_nht_pnc_has_answer(pim, pnc, PIMADDR_ANY)) {
 		/* BSM from a new freshly registered BSR - do a synchronous
 		 * zebra query since otherwise we'd drop the first packet,
 		 * leading to additional delay in picking up BSM data
@@ -479,9 +784,8 @@ bool pim_nht_bsr_rpf_check(struct pim_instance *pim, pim_addr bsr_addr,
 		int num_ifindex;
 
 		memset(nexthop_tab, 0, sizeof(nexthop_tab));
-		num_ifindex = zclient_lookup_nexthop(
-			pim, nexthop_tab, router->multipath, bsr_addr,
-			PIM_NEXTHOP_LOOKUP_MAX);
+		num_ifindex = zclient_lookup_nexthop(pim, nexthop_tab, router->multipath, bsr_addr,
+						     PIMADDR_ANY, PIM_NEXTHOP_LOOKUP_MAX);
 
 		if (num_ifindex <= 0)
 			return false;
@@ -521,7 +825,7 @@ bool pim_nht_bsr_rpf_check(struct pim_instance *pim, pim_addr bsr_addr,
 		return false;
 	}
 
-	if (pim_nht_pnc_is_valid(pim, pnc)) {
+	if (pim_nht_pnc_is_valid(pim, pnc, PIMADDR_ANY)) {
 		/* if we accept BSMs from more than one ECMP nexthop, this will cause
 		 * BSM message "multiplication" for each ECMP hop.  i.e. if you have
 		 * 4-way ECMP and 4 hops you end up with 256 copies of each BSM
@@ -529,7 +833,7 @@ bool pim_nht_bsr_rpf_check(struct pim_instance *pim, pim_addr bsr_addr,
 		 *
 		 * so...  only accept the first (IPv4) valid nexthop as source.
 		 */
-		struct pim_nexthop_cache_rib *rib = pim_pnc_get_rib(pim, pnc);
+		struct pim_nexthop_cache_rib *rib = pim_pnc_get_rib(pim, pnc, PIMADDR_ANY);
 
 		for (nh = rib->nexthop; nh; nh = nh->next) {
 			pim_addr nhaddr;
@@ -768,14 +1072,17 @@ static bool pim_ecmp_nexthop_search(struct pim_instance *pim, struct pim_nexthop
 	pim_addr nh_addr;
 	pim_addr grp_addr;
 	struct pim_nexthop_cache_rib *rib;
+	pim_addr group;
+
+	group = pim_addr_from_prefix(grp);
 
 	/* Early return if required parameters aren't provided */
-	if (!pim || !pnc || !pim_nht_pnc_is_valid(pim, pnc) || !nexthop || !grp)
+	if (!pim || !pnc || !pim_nht_pnc_is_valid(pim, pnc, group) || !nexthop || !grp)
 		return false;
 
 	nh_addr = nexthop->mrib_nexthop_addr;
 	grp_addr = pim_addr_from_prefix(grp);
-	rib = pim_pnc_get_rib(pim, pnc);
+	rib = pim_pnc_get_rib(pim, pnc, group);
 
 	/* Current Nexthop is VALID, check to stay on the current path. */
 	if (nexthop->interface && nexthop->interface->info &&
@@ -948,6 +1255,9 @@ bool pim_nht_lookup_ecmp(struct pim_instance *pim, struct pim_nexthop *nexthop,
 	uint32_t hash_val = 0;
 	uint32_t mod_val = 0;
 	uint32_t num_nbrs = 0;
+	pim_addr group;
+
+	group = pim_addr_from_prefix(grp);
 
 	if (PIM_DEBUG_PIM_NHT_DETAIL)
 		zlog_debug("%s: Looking up: %pPA(%s), last lookup time: %lld", __func__, &src,
@@ -955,12 +1265,12 @@ bool pim_nht_lookup_ecmp(struct pim_instance *pim, struct pim_nexthop *nexthop,
 
 	pnc = pim_nexthop_cache_find(pim, src);
 	if (pnc) {
-		if (pim_nht_pnc_has_answer(pim, pnc))
+		if (pim_nht_pnc_has_answer(pim, pnc, group))
 			return pim_ecmp_nexthop_search(pim, pnc, nexthop, src, grp, neighbor_needed);
 	}
 
 	memset(nexthop_tab, 0, sizeof(struct pim_zlookup_nexthop) * router->multipath);
-	num_ifindex = zclient_lookup_nexthop(pim, nexthop_tab, router->multipath, src,
+	num_ifindex = zclient_lookup_nexthop(pim, nexthop_tab, router->multipath, src, group,
 					     PIM_NEXTHOP_LOOKUP_MAX);
 	if (num_ifindex < 1) {
 		if (PIM_DEBUG_PIM_NHT)
@@ -1065,7 +1375,7 @@ bool pim_nht_lookup_ecmp(struct pim_instance *pim, struct pim_nexthop *nexthop,
 }
 
 bool pim_nht_lookup(struct pim_instance *pim, struct pim_nexthop *nexthop, pim_addr addr,
-		    int neighbor_needed)
+		    pim_addr group, bool neighbor_needed)
 {
 	struct pim_zlookup_nexthop nexthop_tab[router->multipath];
 	struct pim_neighbor *nbr = NULL;
@@ -1101,7 +1411,7 @@ bool pim_nht_lookup(struct pim_instance *pim, struct pim_nexthop *nexthop, pim_a
 			   &addr, nexthop->last_lookup_time, pim->last_route_change_time);
 
 	memset(nexthop_tab, 0, sizeof(struct pim_zlookup_nexthop) * router->multipath);
-	num_ifindex = zclient_lookup_nexthop(pim, nexthop_tab, router->multipath, addr,
+	num_ifindex = zclient_lookup_nexthop(pim, nexthop_tab, router->multipath, addr, group,
 					     PIM_NEXTHOP_LOOKUP_MAX);
 	if (num_ifindex < 1) {
 		if (PIM_DEBUG_PIM_NHT)
@@ -1363,36 +1673,6 @@ void pim_nexthop_update(struct vrf *vrf, struct prefix *match, struct zapi_route
 		pim_crp_nht_update(pim, pnc);
 }
 
-static int pim_nht_hash_mode_update_helper(struct hash_bucket *bucket, void *arg)
-{
-	struct pim_nexthop_cache *pnc = bucket->data;
-	struct pnc_hash_walk_data *pwd = arg;
-	struct pim_instance *pim = pwd->pim;
-
-	if (listcount(pnc->rp_list))
-		pim_update_rp_nh(pim, pnc);
-
-	if (pnc->upstream_hash->count)
-		pim_update_upstream_nh(pim, pnc);
-
-	if (pnc->candrp_count)
-		pim_crp_nht_update(pim, pnc);
-
-	return HASHWALK_CONTINUE;
-}
-
-void pim_nht_mode_changed(struct pim_instance *pim)
-{
-	struct pnc_hash_walk_data pwd;
-
-	/* Update the refresh time to force new lookups if needed */
-	pim_rpf_set_refresh_time(pim);
-
-	/* Force update the registered RP and upstreams for all cache entries */
-	pwd.pim = pim;
-	hash_walk(pim->nht_hash, pim_nht_hash_mode_update_helper, &pwd);
-}
-
 /* Cleanup pim->nht_hash each node data */
 static void pim_nht_hash_clean(void *data)
 {
@@ -1432,11 +1712,19 @@ static bool pim_nht_equal(const void *arg1, const void *arg2)
 void pim_nht_init(struct pim_instance *pim)
 {
 	char hash_name[64];
+	struct pim_lookup_mode *global_mode;
 
 	snprintf(hash_name, sizeof(hash_name), "PIM %s NHT Hash", pim->vrf->name);
 	pim->nht_hash = hash_create_size(256, pim_nht_hash_key, pim_nht_equal, hash_name);
 
-	pim->rpf_mode = MCAST_NO_CONFIG;
+	pim_lookup_mode_init(&(pim->rpf_mode));
+
+	/* Add the default global mode */
+	global_mode = XCALLOC(MTYPE_PIM_LOOKUP_MODE, sizeof(*global_mode));
+	global_mode->grp_plist = NULL;
+	global_mode->src_plist = NULL;
+	global_mode->mode = MCAST_NO_CONFIG;
+	pim_lookup_mode_add(&(pim->rpf_mode), global_mode);
 
 	if (PIM_DEBUG_ZEBRA)
 		zlog_debug("%s: NHT hash init: %s ", __func__, hash_name);
@@ -1446,4 +1734,7 @@ void pim_nht_terminate(struct pim_instance *pim)
 {
 	/* Traverse and cleanup nht_hash */
 	hash_clean_and_free(&pim->nht_hash, (void *)pim_nht_hash_clean);
+
+	pim_lookup_mode_list_free(&(pim->rpf_mode));
+	pim_lookup_mode_fini(&(pim->rpf_mode));
 }
diff --git a/pimd/pim_nht.h b/pimd/pim_nht.h
index 56132a65c..671fa8720 100644
--- a/pimd/pim_nht.h
+++ b/pimd/pim_nht.h
@@ -16,6 +16,15 @@
 #include "pim_rp.h"
 #include "pim_rpf.h"
 
+PREDECL_SORTLIST_NONUNIQ(pim_lookup_mode);
+
+struct pim_lookup_mode {
+	char *grp_plist;
+	char *src_plist;
+	enum pim_rpf_lookup_mode mode;
+	struct pim_lookup_mode_item list;
+};
+
 /* PIM nexthop cache value structure. */
 struct pim_nexthop_cache_rib {
 	/* IGP route's metric. */
@@ -54,6 +63,13 @@ struct pnc_hash_walk_data {
 	struct interface *ifp;
 };
 
+/* Find the right lookup mode for the given group and/or source
+ * either may be ANY (although source should realistically always be provided)
+ * Find the lookup mode that has matching group and/or source prefix lists, or the global mode.
+ */
+enum pim_rpf_lookup_mode pim_get_lookup_mode(struct pim_instance *pim, pim_addr group,
+					     pim_addr source);
+
 /* Change the RPF lookup config, may trigger updates to RP's and Upstreams registered for matching cache entries */
 void pim_nht_change_rpf_mode(struct pim_instance *pim, const char *group_plist,
 			     const char *source_plist, enum pim_rpf_lookup_mode mode);
@@ -62,7 +78,7 @@ void pim_nht_change_rpf_mode(struct pim_instance *pim, const char *group_plist,
 int pim_lookup_mode_write(struct pim_instance *pim, struct vty *vty);
 
 /* Verify that we have nexthop information in the cache entry */
-bool pim_nht_pnc_is_valid(struct pim_instance *pim, struct pim_nexthop_cache *pnc);
+bool pim_nht_pnc_is_valid(struct pim_instance *pim, struct pim_nexthop_cache *pnc, pim_addr group);
 
 /* Get (or add) the NH cache entry for the given address */
 struct pim_nexthop_cache *pim_nht_get(struct pim_instance *pim, pim_addr addr);
@@ -116,7 +132,7 @@ bool pim_nht_lookup_ecmp(struct pim_instance *pim, struct pim_nexthop *nexthop,
  * a synchronous lookup. No ECMP decision is made.
  */
 bool pim_nht_lookup(struct pim_instance *pim, struct pim_nexthop *nexthop, pim_addr addr,
-		    int neighbor_needed);
+		    pim_addr group, bool neighbor_needed);
 
 /* Performs a pim_nht_lookup_ecmp and returns the mroute VIF index of the nexthop interface */
 int pim_nht_lookup_ecmp_if_vif_index(struct pim_instance *pim, pim_addr src, struct prefix *grp);
@@ -124,9 +140,6 @@ int pim_nht_lookup_ecmp_if_vif_index(struct pim_instance *pim, pim_addr src, str
 /* Tracked nexthop update from zebra */
 void pim_nexthop_update(struct vrf *vrf, struct prefix *match, struct zapi_route *nhr);
 
-/* RPF lookup mode changed via configuration */
-void pim_nht_mode_changed(struct pim_instance *pim);
-
 /* NHT init and finish funcitons */
 void pim_nht_init(struct pim_instance *pim);
 void pim_nht_terminate(struct pim_instance *pim);
diff --git a/pimd/pim_zlookup.c b/pimd/pim_zlookup.c
index febc595ad..4ffb5bac1 100644
--- a/pimd/pim_zlookup.c
+++ b/pimd/pim_zlookup.c
@@ -375,12 +375,16 @@ static int zclient_rib_lookup(struct pim_instance *pim, struct pim_zlookup_nexth
 
 static int zclient_lookup_nexthop_once(struct pim_instance *pim,
 				       struct pim_zlookup_nexthop nexthop_tab[], const int tab_size,
-				       pim_addr addr)
+				       pim_addr addr, pim_addr group)
 {
-	if (pim->rpf_mode == MCAST_MRIB_ONLY)
+	enum pim_rpf_lookup_mode mode;
+
+	mode = pim_get_lookup_mode(pim, group, addr);
+
+	if (mode == MCAST_MRIB_ONLY)
 		return zclient_rib_lookup(pim, nexthop_tab, tab_size, addr, SAFI_MULTICAST);
 
-	if (pim->rpf_mode == MCAST_URIB_ONLY)
+	if (mode == MCAST_URIB_ONLY)
 		return zclient_rib_lookup(pim, nexthop_tab, tab_size, addr, SAFI_UNICAST);
 
 	/* All other modes require looking up both tables and making a choice */
@@ -420,15 +424,14 @@ static int zclient_lookup_nexthop_once(struct pim_instance *pim,
 	/* Both tables have results, so compare them. Distance and prefix length are the same for all
 	 * nexthops, so only compare the first in the list
 	 */
-	if (pim->rpf_mode == MCAST_MIX_DISTANCE &&
+	if (mode == MCAST_MIX_DISTANCE &&
 	    mrib_tab[0].protocol_distance > urib_tab[0].protocol_distance) {
 		if (PIM_DEBUG_PIM_NHT_DETAIL)
 			zlog_debug("%s: addr=%pPAs(%s), URIB has shortest distance", __func__,
 				   &addr, pim->vrf->name);
 		memcpy(nexthop_tab, urib_tab, sizeof(struct pim_zlookup_nexthop) * tab_size);
 		return urib_num;
-	} else if (pim->rpf_mode == MCAST_MIX_PFXLEN &&
-		   mrib_tab[0].prefix_len < urib_tab[0].prefix_len) {
+	} else if (mode == MCAST_MIX_PFXLEN && mrib_tab[0].prefix_len < urib_tab[0].prefix_len) {
 		if (PIM_DEBUG_PIM_NHT_DETAIL)
 			zlog_debug("%s: addr=%pPAs(%s), URIB has lengthest prefix length", __func__,
 				   &addr, pim->vrf->name);
@@ -459,15 +462,13 @@ void zclient_lookup_read_pipe(struct event *thread)
 		return;
 	}
 
-	zclient_lookup_nexthop_once(pim, nexthop_tab, 10, l);
+	zclient_lookup_nexthop_once(pim, nexthop_tab, 10, l, PIMADDR_ANY);
 	event_add_timer(router->master, zclient_lookup_read_pipe, zlookup, 60,
 			&zlookup_read);
 }
 
-int zclient_lookup_nexthop(struct pim_instance *pim,
-			   struct pim_zlookup_nexthop nexthop_tab[],
-			   const int tab_size, pim_addr addr,
-			   int max_lookup)
+int zclient_lookup_nexthop(struct pim_instance *pim, struct pim_zlookup_nexthop nexthop_tab[],
+			   const int tab_size, pim_addr addr, pim_addr group, int max_lookup)
 {
 	int lookup;
 	uint32_t route_metric = 0xFFFFFFFF;
@@ -480,8 +481,7 @@ int zclient_lookup_nexthop(struct pim_instance *pim,
 		int first_ifindex;
 		pim_addr nexthop_addr;
 
-		num_ifindex = zclient_lookup_nexthop_once(pim, nexthop_tab,
-							  tab_size, addr);
+		num_ifindex = zclient_lookup_nexthop_once(pim, nexthop_tab, tab_size, addr, group);
 		if (num_ifindex < 1) {
 			if (PIM_DEBUG_PIM_NHT_DETAIL)
 				zlog_debug(
diff --git a/pimd/pim_zlookup.h b/pimd/pim_zlookup.h
index c9461eb7e..720cc4fca 100644
--- a/pimd/pim_zlookup.h
+++ b/pimd/pim_zlookup.h
@@ -27,10 +27,8 @@ struct pim_zlookup_nexthop {
 void zclient_lookup_new(void);
 void zclient_lookup_free(void);
 
-int zclient_lookup_nexthop(struct pim_instance *pim,
-			   struct pim_zlookup_nexthop nexthop_tab[],
-			   const int tab_size, pim_addr addr,
-			   int max_lookup);
+int zclient_lookup_nexthop(struct pim_instance *pim, struct pim_zlookup_nexthop nexthop_tab[],
+			   const int tab_size, pim_addr addr, pim_addr group, int max_lookup);
 
 void pim_zlookup_show_ip_multicast(struct vty *vty);