Zebra: Ensure we compare prefix and NHs when checking if NH changed

In nexthop tracking, the code currently compares the nexthop state of the
resolved_route for a prefix with the previous nexthop state. However, if
the resolved route itself changes, we can end up comparing the RIBs of
unrelated prefixes and assuming that nothing has changed. To fix this, we
need to store and compare the new resolved route with the previously
resolved route. If this has changed, assume the NH associated with a route
has changed.

Signed-off-by: Dinesh G Dutt <ddutt@cumulusnetworks.com>
Reviewed-by:   Vivek Venkataraman <vivek@cumulusnetworks.com>

diff --git a/lib/prefix.c b/lib/prefix.c
index dbfdc83012d564f830b797dc5ad115c42242d0f7..739764842d0784df9276b401409a9dd6bb77e655 100644 (file)
--- a/lib/prefix.c
+++ b/lib/prefix.c
@@ -278,6 +278,12 @@ prefix_copy (struct prefix *dest, const struct prefix *src)
 int
 prefix_same (const struct prefix *p1, const struct prefix *p2)
 {
+  if ((p1 && !p2) || (!p1 && p2))
+    return 0;
+
+  if (!p1 && !p2)
+    return 1;
+
   if (p1->family == p2->family && p1->prefixlen == p2->prefixlen)
     {
       if (p1->family == AF_INET)

diff --git a/zebra/zebra_rnh.c b/zebra/zebra_rnh.c
index 9b1c978ef7cd773fdc63d227eaab17e3df368d3a..380d06522b24a53d7f0c951d90f00aaef26f840f 100644 (file)
--- a/zebra/zebra_rnh.c
+++ b/zebra/zebra_rnh.c
@@ -266,6 +266,7 @@ zebra_evaluate_rnh_table (int vrfid, int family, int force)
   char bufs[INET6_ADDRSTRLEN];
   struct route_node *static_rn;
   struct nexthop *nexthop;
+
   ntable = lookup_rnh_table(vrfid, family);
   if (!ntable)
     {
@@ -312,7 +313,21 @@ zebra_evaluate_rnh_table (int vrfid, int family, int force)
 
       state_changed = 0;
 
-      if (compare_state(rib, rnh->state))
+      /* Ensure prefixes we're resolving over have stayed the same */
+      if (!prefix_same(&rnh->resolved_route, &prn->p))
+       {
+         if (rib)
+           UNSET_FLAG(rib->status, RIB_ENTRY_NEXTHOPS_CHANGED);
+
+         if (prn)
+           prefix_copy(&rnh->resolved_route, &prn->p);
+         else
+           memset(&rnh->resolved_route, 0, sizeof(struct prefix));
+
+         copy_state(rnh, rib, nrn);
+         state_changed = 1;
+       }
+      else if (compare_state(rib, rnh->state))
        {
          if (rib)
            UNSET_FLAG(rib->status, RIB_ENTRY_NEXTHOPS_CHANGED);

diff --git a/zebra/zebra_rnh.h b/zebra/zebra_rnh.h
index af56d36aaa88afb6859130bce1536f642a2732c9..f18679dad335f920dbc6d594aaa275422bd2539d 100644 (file)
--- a/zebra/zebra_rnh.h
+++ b/zebra/zebra_rnh.h
@@ -33,6 +33,7 @@ struct rnh
 #define ZEBRA_NHT_CONNECTED    0x1
 #define ZEBRA_NHT_DELETED       0x2
   struct rib *state;
+  struct prefix resolved_route;
   struct list *client_list;
   struct list *zebra_static_route_list; /* static routes dependent on this NH */
   struct route_node *node;