mac-learning: Refactor to increase generality.

In an upcoming commit I want to store a pointer in MAC learning entries
in the bridge, instead of an integer port number.  The MAC learning library
has other clients, and the others do not gracefully fit this new model, so
in fact the data will have to become a union.  However, this does not fit
well with the current mac_learning API, since mac_learning_learn()
currently initializes and compares the data.  It seems better to break up
the API so that only the client has to know the data's format and how to
initialize it or compare it.  This commit makes this possible.

This commit doesn't change the type of the data stored in a MAC learning
entry yet.

As a side effect this commit has the benefit that clients that don't need
gratuitous ARP locking don't have to specify any policy for it at all.

1 files changed, 45 insertions, 20 deletions

diff --git a/lib/mac-learning.h b/lib/mac-learning.h
index 89a4e909..c5c94bb3 100644
--- a/lib/mac-learning.h
+++ b/lib/mac-learning.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2009, 2010 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010, 2011 Nicira Networks.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@
 #include "list.h"
 #include "packets.h"
 #include "tag.h"
+#include "timeval.h"
 
 #define MAC_HASH_BITS 10
 #define MAC_HASH_MASK (MAC_HASH_SIZE - 1)
@@ -35,12 +36,6 @@
  * relearning based on a reflection from a bond slave. */
 #define MAC_GRAT_ARP_LOCK_TIME 5
 
-enum grat_arp_lock_type {
-    GRAT_ARP_LOCK_NONE,
-    GRAT_ARP_LOCK_SET,
-    GRAT_ARP_LOCK_CHECK
-};
-
 /* A MAC learning table entry. */
 struct mac_entry {
     struct list hash_node;      /* Element in a mac_learning 'table' list. */
@@ -55,6 +50,27 @@ struct mac_entry {
 
 int mac_entry_age(const struct mac_entry *);
 
+/* Returns true if mac_learning_insert() just created 'mac' and the caller has
+ * not yet properly initialized it. */
+static inline bool mac_entry_is_new(const struct mac_entry *mac)
+{
+    return !mac->tag;
+}
+
+/* Sets a gratuitous ARP lock on 'mac' that will expire in
+ * MAC_GRAT_ARP_LOCK_TIME seconds. */
+static inline void mac_entry_set_grat_arp_lock(struct mac_entry *mac)
+{
+    mac->grat_arp_lock = time_now() + MAC_GRAT_ARP_LOCK_TIME;
+}
+
+/* Returns true if a gratuitous ARP lock is in effect on 'mac', false if none
+ * has ever been asserted or if it has expired. */
+static inline bool mac_entry_is_grat_arp_locked(const struct mac_entry *mac)
+{
+    return time_now() >= mac->grat_arp_lock;
+}
+
 /* MAC learning table. */
 struct mac_learning {
     struct list free;           /* Not-in-use entries. */
@@ -66,23 +82,32 @@ struct mac_learning {
     unsigned long *flood_vlans; /* Bitmap of learning disabled VLANs. */
 };
 
+/* Basics. */
 struct mac_learning *mac_learning_create(void);
 void mac_learning_destroy(struct mac_learning *);
+
+void mac_learning_run(struct mac_learning *, struct tag_set *);
+void mac_learning_wait(struct mac_learning *);
+
+/* Configuration. */
 bool mac_learning_set_flood_vlans(struct mac_learning *,
                                   unsigned long *bitmap);
-tag_type mac_learning_learn(struct mac_learning *,
-                            const uint8_t src[ETH_ADDR_LEN], uint16_t vlan,
-                            uint16_t src_port, enum grat_arp_lock_type
-                            lock_type);
-int mac_learning_lookup(const struct mac_learning *,
-                        const uint8_t dst[ETH_ADDR_LEN], uint16_t vlan,
-                        bool *is_grat_arp_locked);
-int mac_learning_lookup_tag(const struct mac_learning *,
-                            const uint8_t dst[ETH_ADDR_LEN],
-                            uint16_t vlan, tag_type *tag,
-                            bool *is_grat_arp_locked);
+
+/* Learning. */
+bool mac_learning_may_learn(const struct mac_learning *,
+                            const uint8_t src_mac[ETH_ADDR_LEN],
+                            uint16_t vlan);
+struct mac_entry *mac_learning_insert(struct mac_learning *,
+                                      const uint8_t src[ETH_ADDR_LEN],
+                                      uint16_t vlan);
+tag_type mac_learning_changed(struct mac_learning *, struct mac_entry *);
+
+/* Lookup. */
+struct mac_entry *mac_learning_lookup(const struct mac_learning *,
+                                      const uint8_t dst[ETH_ADDR_LEN],
+                                      uint16_t vlan, tag_type *);
+
+/* Flushing. */
 void mac_learning_flush(struct mac_learning *);
-void mac_learning_run(struct mac_learning *, struct tag_set *);
-void mac_learning_wait(struct mac_learning *);
 
 #endif /* mac-learning.h */