Bugfix for check overlap flag

We didn't detect flow-mod conflict when adding a finer granularity
flow which conflicts with an installed, coarser granularity flow.

Thanks Justin for pointing this out :
https://mailman.stanford.edu/pipermail/openflow-dev/2009-November/000529.html

udatapath/switch-flow.c

@@ -105,6 +105,21 @@ flow_matches_desc(const struct sw_flow_key *t, const struct sw_flow_key *d,
     return flow_matches_1wild(t, d);
 }
 
+/* Returns nonzero if 't' (the table entry's key) and 'd' (the key
+ * describing the match) match, that is, if their fields are
+ * equal modulo 't' or 'd' wildcards, zero otherwise.  If 'strict' is nonzero, the
+ * wildcards must match in both 't_key' and 'd_key'.  Note that the
+ * table's wildcards are ignored unless 'strict' is set. */
+int
+flow_matches_2desc(const struct sw_flow_key *t, const struct sw_flow_key *d,
+        int strict)
+{
+    if (strict && d->wildcards != t->wildcards) {
+        return 0;
+    }
+    return flow_matches_2wild(t, d);
+}
+
 void
 flow_extract_match(struct sw_flow_key* to, const struct ofp_match* from)
 {

udatapath/switch-flow.h

@@ -81,6 +81,8 @@ int flow_matches_1wild(const struct sw_flow_key *, const struct sw_flow_key *);
 int flow_matches_2wild(const struct sw_flow_key *, const struct sw_flow_key *);
 int flow_matches_desc(const struct sw_flow_key *, const struct sw_flow_key *, 
                      int);
+int flow_matches_2desc(const struct sw_flow_key *, const struct sw_flow_key *,
+                     int);
 int flow_has_out_port(struct sw_flow *flow, uint16_t out_port);
 struct sw_flow *flow_alloc(size_t);
 void flow_setup_actions(struct sw_flow *, const struct ofp_action_header *, int);

udatapath/table-hash.c

@@ -133,7 +133,7 @@ static int table_hash_has_conflict(struct sw_table *swt,
     if (key->wildcards == 0) {
         struct sw_flow **bucket = find_bucket(swt, key);
         struct sw_flow *flow = *bucket;
-        if (flow && flow_matches_desc(&flow->key, key,strict)
+        if (flow && flow_matches_2desc(&flow->key, key,strict)
                 && (flow->priority == priority)) {
             return true;
         }
@@ -143,7 +143,7 @@ static int table_hash_has_conflict(struct sw_table *swt,
         for (i = 0; i <= th->bucket_mask; i++) {
             struct sw_flow **bucket = &th->buckets[i];
             struct sw_flow *flow = *bucket;
-            if (flow && flow_matches_desc(&flow->key, key, strict)
+            if (flow && flow_matches_2desc(&flow->key, key, strict)
                     && (flow->priority == priority)) {
                 return true;
             }

udatapath/table-linear.c

@@ -127,7 +127,7 @@ static int table_linear_has_conflict(struct sw_table *swt,
     struct sw_flow *flow;
 
     LIST_FOR_EACH (flow, struct sw_flow, node, &tl->flows) {
-        if (flow_matches_desc(&flow->key, key, strict)
+        if (flow_matches_2desc(&flow->key, key, strict)
                 && (flow->priority == priority)) {
             return true;
         }