[ovs-dev] [learning v2 18/19] ofproto-dpif: Introduce an enum for the number of tables.

[Ben Pfaff]

It seems reasonable that someone might want to reduce this number, so
make it an enum to simplify that.

If someone does reduce the number then rule_dpif_lookup() needs to validate
the table_id, so add code to do that too.
---
 ofproto/ofproto-dpif.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
index bbd9b6a..43e236d 100644
--- a/ofproto/ofproto-dpif.c
+++ b/ofproto/ofproto-dpif.c
@@ -65,6 +65,9 @@ COVERAGE_DEFINE(facet_unexpected);
  * flow translation. */
 #define MAX_RESUBMIT_RECURSION 16
 
+/* Number of implemented OpenFlow tables.  Must be between 1 and 255. */
+enum { N_TABLES = 255 };
+
 struct ofport_dpif;
 struct ofproto_dpif;
 
@@ -473,7 +476,7 @@ construct(struct ofproto *ofproto_, int *n_tablesp)
 
     ofproto->has_bundle_action = false;
 
-    *n_tablesp = 255;
+    *n_tablesp = N_TABLES;
     return 0;
 }
 
@@ -2613,6 +2616,10 @@ static struct rule_dpif *
 rule_dpif_lookup(struct ofproto_dpif *ofproto, const struct flow *flow,
                  uint8_t table_id)
 {
+    if (table_id >= N_TABLES) {
+        return NULL;
+    }
+
     return rule_dpif_cast(rule_from_cls_rule(
                               classifier_lookup(&ofproto->up.tables[table_id],
                                                 flow)));
-- 
1.7.4.4