Nest: Fix race condition during reconfiguration

If export filter is changed during reconfiguration and a route disappears
between reconfiguration and refeed (e.g., if the route is a static route
also removed during the reconfiguration), the route is not withdrawn.
The patch fixes that by adding tx reconfiguration timestamp.

3 files changed, 16 insertions, 10 deletions

diff --git a/nest/proto.c b/nest/proto.c
index 552d53ae..565b238f 100644
--- a/nest/proto.c
+++ b/nest/proto.c
@@ -433,10 +433,17 @@ proto_reconfigure(struct proto *p, struct proto_config *oc, struct proto_config
   if (p->proto->multitable)
     return 1;
 
+  int import_changed = ! filter_same(nc->in_filter, oc->in_filter);
+  int export_changed = ! filter_same(nc->out_filter, oc->out_filter);
+
+  /* We treat a change in preferences by reimporting routes */
+  if (nc->preference != oc->preference)
+    import_changed = 1;
+
   /* Update filters and limits in the main announce hook
      Note that this also resets limit state */
   if (p->main_ahook)
-    {  
+    {
       struct announce_hook *ah = p->main_ahook;
       ah->in_filter = nc->in_filter;
       ah->out_filter = nc->out_filter;
@@ -445,6 +452,9 @@ proto_reconfigure(struct proto *p, struct proto_config *oc, struct proto_config
       ah->out_limit = nc->out_limit;
       ah->in_keep_filtered = nc->in_keep_filtered;
       proto_verify_limits(ah);
+
+      if (export_changed)
+	ah->last_out_filter_change = now;
     }
 
   /* Update routes when filters changed. If the protocol in not UP,
@@ -452,13 +462,6 @@ proto_reconfigure(struct proto *p, struct proto_config *oc, struct proto_config
   if ((p->proto_state != PS_UP) || (type == RECONFIG_SOFT))
     return 1;
 
-  int import_changed = ! filter_same(nc->in_filter, oc->in_filter);
-  int export_changed = ! filter_same(nc->out_filter, oc->out_filter);
-
-  /* We treat a change in preferences by reimporting routes */
-  if (nc->preference != oc->preference)
-    import_changed = 1;
-
   if (import_changed || export_changed)
     log(L_INFO "Reloading protocol %s", p->name);
 
diff --git a/nest/protocol.h b/nest/protocol.h
index 5aca9a4e..4fb76e2b 100644
--- a/nest/protocol.h
+++ b/nest/protocol.h
@@ -471,6 +471,7 @@ struct announce_hook {
   struct proto_stats *stats;		/* Per-table protocol statistics */
   struct announce_hook *next;		/* Next hook for the same protocol */
   int in_keep_filtered;			/* Routes rejected in import filter are kept */
+  bird_clock_t last_out_filter_change;	/* Last time when out_filter _changed_ */
 };
 
 struct announce_hook *proto_add_announce_hook(struct proto *p, struct rtable *t, struct proto_stats *stats);
diff --git a/nest/rt-table.c b/nest/rt-table.c
index 28fe5baa..07bb0b12 100644
--- a/nest/rt-table.c
+++ b/nest/rt-table.c
@@ -426,13 +426,15 @@ rt_notify_basic(struct announce_hook *ah, net *net, rte *new0, rte *old0, int re
    * reconfiguration and the end of refeed - if a newly filtered
    * route disappears during this period, proper withdraw is not
    * sent (because old would be also filtered) and the route is
-   * not refeeded (because it disappeared before that).
+   * not refeeded (because it disappeared before that). Therefore,
+   * we also do not try to run the filter on old routes that are
+   * older than the last filter change.
    */
 
   if (new)
     new = export_filter(ah, new, &new_free, &tmpa, 0);
 
-  if (old && !refeed)
+  if (old && !(refeed || (old->lastmod <= ah->last_out_filter_change)))
     old = export_filter(ah, old, &old_free, NULL, 1);
 
   if (!new && !old)