bgpd: fix several issues in sourcing AIGP attribute

Fix several issues in sourcing AIGP attribute:

1) AIGP should not be set as default for a redistributed route or a
   static network. It should be set by config instead.

2) AIGP sourced by "set aigp-metric igp-metric" in a route-map does
   not set the correct value for a redistributed route.

3) When redistribute a connected route like loopback, the AGIP (with
   value 0) is sourced by "set aigp-metric igp-metric", but the
   attribute is not propagated as the attribute flag is not set.

Signed-off-by: Enke Chen <enchen@paloaltonetworks.com>

bgpd/bgp_attr.h

@@ -593,9 +593,7 @@ static inline uint64_t bgp_attr_get_aigp_metric(const struct attr *attr)
 static inline void bgp_attr_set_aigp_metric(struct attr *attr, uint64_t aigp)
 {
 	attr->aigp_metric = aigp;
-
-	if (aigp)
-		SET_FLAG(attr->flag, ATTR_FLAG_BIT(BGP_ATTR_AIGP));
+	SET_FLAG(attr->flag, ATTR_FLAG_BIT(BGP_ATTR_AIGP));
 }
 
 static inline uint64_t bgp_aigp_metric_total(struct bgp_path_info *bpi)

bgpd/bgp_route.c

@@ -6754,9 +6754,6 @@ void bgp_static_update(struct bgp *bgp, const struct prefix *p,
 	if (afi == AFI_IP)
 		attr.mp_nexthop_len = BGP_ATTR_NHLEN_IPV4;
 
-	if (bgp_static->igpmetric)
-		bgp_attr_set_aigp_metric(&attr, bgp_static->igpmetric);
-
 	if (bgp_static->atomic)
 		attr.flag |= ATTR_FLAG_BIT(BGP_ATTR_ATOMIC_AGGREGATE);
 
@@ -9020,9 +9017,6 @@ void bgp_redistribute_add(struct bgp *bgp, struct prefix *p,
 	attr.distance = distance;
 	attr.tag = tag;
 
-	if (metric)
-		bgp_attr_set_aigp_metric(&attr, metric);
-
 	afi = family2afi(p->family);
 
 	red = bgp_redist_lookup(bgp, afi, type, instance);
@@ -9032,10 +9026,8 @@ void bgp_redistribute_add(struct bgp *bgp, struct prefix *p,
 		/* Copy attribute for modification. */
 		attr_new = attr;
 
-		if (red->redist_metric_flag) {
+		if (red->redist_metric_flag)
 			attr_new.med = red->redist_metric;
-			bgp_attr_set_aigp_metric(&attr_new, red->redist_metric);
-		}
 
 		/* Apply route-map. */
 		if (red->rmap.name) {

bgpd/bgp_routemap.c

@@ -3524,19 +3524,15 @@ route_set_aigp_metric(void *rule, const struct prefix *pfx, void *object)
 {
 	const char *aigp_metric = rule;
 	struct bgp_path_info *path = object;
-	uint32_t aigp = 0;
+	uint32_t aigp;
 
-	if (strmatch(aigp_metric, "igp-metric")) {
-		if (!path->nexthop)
-			return RMAP_NOMATCH;
-
-		bgp_attr_set_aigp_metric(path->attr, path->nexthop->metric);
-	} else {
+	/* Note: the metric is stored as MED for a locally redistributed. */
+	if (strmatch(aigp_metric, "igp-metric"))
+		aigp = path->nexthop ? path->nexthop->metric : path->attr->med;
+	else
 		aigp = atoi(aigp_metric);
-		bgp_attr_set_aigp_metric(path->attr, aigp);
-	}
 
-	path->attr->flag |= ATTR_FLAG_BIT(BGP_ATTR_AIGP);
+	bgp_attr_set_aigp_metric(path->attr, aigp);
 
 	return RMAP_OKAY;
 }