From 7601e582848ef68c565f3d88ab1265e4c86d5ac0 Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Sat, 6 Oct 2012 04:13:01 +0200
Subject: Fix feasibility distance maintenance

---
 ffd/ffd.h | 75 +++++++++++++++++++++++++++++++++++++++++----------------------
 1 file changed, 49 insertions(+), 26 deletions(-)

(limited to 'ffd/ffd.h')

diff --git a/ffd/ffd.h b/ffd/ffd.h
index 0b1c296..f498f4e 100644
--- a/ffd/ffd.h
+++ b/ffd/ffd.h
@@ -50,35 +50,11 @@ typedef struct __attribute__((packed)) _ffd_node_id_t {
 	uint8_t id[8];
 } ffd_node_id_t;
 
-
-#define FFD_NODE_ID_UNSPEC ((ffd_node_id_t){})
-
-
-static inline bool ffd_is_node_id_unspec(const ffd_node_id_t *node) {
-	const uint8_t *id = node->id;
-
-	if (id[0]||id[1]||id[2]||id[3]||id[4]||id[5]||id[6]||id[7])
-		return false;
-	else
-		return true;
-}
-
-static inline bool ffd_are_node_ids_equal(const ffd_node_id_t *id1, const ffd_node_id_t *id2) {
-	const uint8_t *a = id1->id;
-	const uint8_t *b = id2->id;
-
-	return (a[0]==b[0] && a[1]==b[1] && a[2]==b[2] && a[3]==b[3]
-		&& a[4]==b[4] && a[5]==b[5] && a[6]==b[6] && a[7]==b[7]);
-}
-
-
 typedef struct _ffd_metric_seqno_t {
 	uint16_t metric;
 	uint16_t seqno;
 } ffd_metric_seqno_t;
 
-#define FFD_IS_INFINITY(m) ((m).metric == 0xffff)
-
 typedef struct _ffd_nexthop_t {
 	struct _ffd_nexthop_t *next;
 
@@ -96,6 +72,7 @@ typedef struct _ffd_announce_t {
 	uint16_t type;
 	uint16_t key;
 
+	ffd_metric_seqno_t metric;
 	ffd_metric_seqno_t feasibility_distance;
 
 	ffd_nexthop_t *selected;
@@ -147,8 +124,54 @@ extern int sockfd;
 extern struct timespec now;
 
 
-bool ffd_is_feasible(const ffd_announce_t *announce, ffd_metric_seqno_t ms);
-ffd_metric_seqno_t ffd_announce_get_metric(const ffd_announce_t *announce);
+#define FFD_NODE_ID_UNSPEC ((ffd_node_id_t){})
+
+
+static inline bool ffd_is_node_id_unspec(const ffd_node_id_t *node) {
+	const uint8_t *id = node->id;
+
+	if (id[0]||id[1]||id[2]||id[3]||id[4]||id[5]||id[6]||id[7])
+		return false;
+	else
+		return true;
+}
+
+static inline bool ffd_are_node_ids_equal(const ffd_node_id_t *id1, const ffd_node_id_t *id2) {
+	const uint8_t *a = id1->id;
+	const uint8_t *b = id2->id;
+
+	return (a[0]==b[0] && a[1]==b[1] && a[2]==b[2] && a[3]==b[3]
+		&& a[4]==b[4] && a[5]==b[5] && a[6]==b[6] && a[7]==b[7]);
+}
+
+#define FFD_IS_INFINITY(m) ((m).metric == 0xffff)
+
+/* returns true if ms1 is better than ms2 */
+static inline bool ffd_is_metric_better(ffd_metric_seqno_t ms1, ffd_metric_seqno_t ms2) {
+	if (FFD_IS_INFINITY(ms1))
+		return false;
+
+	if (FFD_IS_INFINITY(ms2))
+		return true;
+
+	int16_t seqno_diff = ms2.seqno - ms1.seqno;
+
+	if (seqno_diff < 0)
+		return true;
+	if (seqno_diff == 0 && ms1.metric < ms2.metric)
+		return true;
+
+	return false;
+}
+
+static inline bool ffd_is_feasible(const ffd_announce_t *announce, ffd_metric_seqno_t ms) {
+	if (FFD_IS_INFINITY(ms))
+		return true;
+
+	return ffd_is_metric_better(ms, announce->feasibility_distance);
+}
+
+
 void ffd_announce_update(ffd_announce_t *announce, ffd_nexthop_t *nexthop, ffd_metric_seqno_t ms, uint16_t interval);
 ffd_announce_t* ffd_announce_new(void);
 
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