Fix feasibility distance maintenance

3 files changed, 56 insertions, 47 deletions

diff --git a/ffd/announce.c b/ffd/announce.c
index e1f7ae0..8911feb 100644
--- a/ffd/announce.c
+++ b/ffd/announce.c
@@ -28,20 +28,6 @@
 #include "neigh.h"
 
 
-bool ffd_is_feasible(const ffd_announce_t *announce, ffd_metric_seqno_t ms) {
-	if (FFD_IS_INFINITY(ms) || FFD_IS_INFINITY(announce->feasibility_distance))
-		return true;
-
-	int16_t seqno_diff = ms.seqno - announce->feasibility_distance.seqno;
-
-	if (seqno_diff < 0)
-		return true;
-	if (seqno_diff == 0 && ms.metric < announce->feasibility_distance.metric)
-		return true;
-
-	return false;
-}
-
 static ffd_nexthop_t* select_nexthop(const ffd_announce_t *announce) {
 	uint16_t ret_metric = 0xffff;
 	ffd_nexthop_t *ret = NULL;
@@ -62,7 +48,7 @@ static ffd_nexthop_t* select_nexthop(const ffd_announce_t *announce) {
 	return ret;
 }
 
-ffd_metric_seqno_t ffd_announce_get_metric(const ffd_announce_t *announce) {
+ffd_metric_seqno_t get_metric(const ffd_announce_t *announce) {
 	if (announce->selected) {
 		uint32_t metric = announce->selected->metric_seqno.metric + ffd_neigh_get_cost(announce->selected->neigh);
 
@@ -75,6 +61,7 @@ ffd_metric_seqno_t ffd_announce_get_metric(const ffd_announce_t *announce) {
 
 static inline void update_selected(ffd_announce_t *announce) {
 	announce->selected = select_nexthop(announce);
+	announce->metric = get_metric(announce);
 }
 
 void ffd_announce_update(ffd_announce_t *announce, ffd_nexthop_t *nexthop, ffd_metric_seqno_t ms, uint16_t interval) {
@@ -90,7 +77,7 @@ void ffd_announce_update(ffd_announce_t *announce, ffd_nexthop_t *nexthop, ffd_m
 ffd_announce_t* ffd_announce_new(void) {
 	ffd_announce_t *a = calloc(1, sizeof(ffd_announce_t));
 
-	a->feasibility_distance.metric = 0xffff;
+	a->metric.metric = a->feasibility_distance.metric = 0xffff;
 
 	a->next = announce_list;
 	announce_list = a;
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);
 
diff --git a/ffd/send.c b/ffd/send.c
index 142d07a..ac5b250 100644
--- a/ffd/send.c
+++ b/ffd/send.c
@@ -164,13 +164,11 @@ static bool add_update(ffd_packet_t *packet, size_t max_len, ffd_node_id_t *node
 		return false;
 	}
 
-	ffd_metric_seqno_t metric = ffd_announce_get_metric(announce);
-
 	update->flags = 0;
 	update->reserved = 0;
 	update->interval = htons(FFD_UPDATE_INTERVAL);
-	update->seqno = htons(metric.seqno);
-	update->metric = htons(metric.metric);
+	update->seqno = htons(announce->metric.seqno);
+	update->metric = htons(announce->metric.metric);
 	update->type = htons(announce->type);
 	update->key = htons(announce->key);
 
@@ -182,7 +180,8 @@ static bool add_update(ffd_packet_t *packet, size_t max_len, ffd_node_id_t *node
 		}
 	}
 
-	announce->feasibility_distance = metric;
+	if (ffd_is_metric_better(announce->metric, announce->feasibility_distance))
+	    announce->feasibility_distance = announce->metric;
 
 	return true;
 }