From: Donald Sharp <sharpd@cumulusnetworks.com>
Date: Tue, 29 Aug 2017 13:46:12 +0000 (-0400)
Subject: pimd: Match on longest prefix when searching for RP
X-Git-Tag: frr-4.0-dev~275^2~1
X-Git-Url: https://git.puffer.fish/?a=commitdiff_plain;h=b77b155068fccde782700e342d745f2090886223;p=mirror%2Ffrr.git

pimd: Match on longest prefix when searching for RP

When we are searching for a RP to use, amongst
many RP's and separate prefix-lists, Match on
the longest prefix specified to choose the
correct RP.

Example:
ip pim rp 4.3.2.1 prefix-list A
ip pim rp 4.3.2.2 prefix-list B
ip pim rp 4.3.2.3 prefix-list C

ip prefix-list A seq 5 permit 225.0.0.0/8
ip prefix-list B seq 5 permit 225.1.0.0/16
ip prefix-list C seq 5 permit 225.1.1.0/24

Old behavior:  Group 225.1.1.14 comes in and
we need to find the RP to use, we would match
on the first prefix-list A( since we are searching
based on a sorted link list of RP address ) and
select 4.3.2.1 as our RP

New behavior:  Group 225.1.1.14 comes in and
we need to find theRP to use, we now will
match on C( longest prefix match ) and select
4.3.2.3 as our RP.

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

diff --git a/pimd/pim_rp.c b/pimd/pim_rp.c
index ff89a1bdd2..423d49a1b9 100644
--- a/pimd/pim_rp.c
+++ b/pimd/pim_rp.c
@@ -198,23 +198,35 @@ static struct rp_info *pim_rp_find_match_group(struct pim_instance *pim,
 					       struct prefix *group)
 {
 	struct listnode *node;
+	struct rp_info *best = NULL;
 	struct rp_info *rp_info;
 	struct prefix_list *plist;
+	struct prefix *p, *bp;
 
 	for (ALL_LIST_ELEMENTS_RO(pim->rp_list, node, rp_info)) {
 		if (rp_info->plist) {
 			plist = prefix_list_lookup(AFI_IP, rp_info->plist);
 
-			if (plist
-			    && prefix_list_apply(plist, group) == PREFIX_PERMIT)
-				return rp_info;
+			if (prefix_list_apply_which_prefix(plist, &p, group) == PREFIX_DENY)
+				continue;
+
+			if (!best) {
+				best = rp_info;
+				bp = p;
+				continue;
+			}
+
+			if (bp->prefixlen < p->prefixlen) {
+				best = rp_info;
+				bp = p;
+			}
 		} else {
 			if (prefix_match(&rp_info->group, group))
 				return rp_info;
 		}
 	}
 
-	return NULL;
+	return best;
 }
 
 /*