bgpd: Fix display when using missing-as-worst

The usage of the `bgp bestpath med missing-as-worst` command was being accepted and applied during bestpath, but during output of the routes affected by this it would not give any indication that this was happening or what med value was being used. Fixes: FRRouting#15718 Signed-off-by: Donald Sharp <[email protected]>
donaldsharp · Apr 15, 2024 · bc9885b · bc9885b
1 parent 572b6f3
commit bc9885b
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Showing 5 changed files with 65 additions and 38 deletions.
diff --git a/bgpd/bgp_route.c b/bgpd/bgp_route.c
@@ -553,6 +553,15 @@ void bgp_path_info_unset_flag(struct bgp_dest *dest, struct bgp_path_info *pi,
 	bgp_pcount_adjust(dest, pi);
 }
 
+static bool use_bgp_med_value(struct attr *attr, struct bgp *bgp)
+{
+	if (attr->flag & ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC) ||
+	    CHECK_FLAG(bgp->flags, BGP_FLAG_MED_MISSING_AS_WORST))
+		return true;
+
+	return false;
+}
+
 /* Get MED value.  If MED value is missing and "bgp bestpath
    missing-as-worst" is specified, treat it as the worst value. */
 static uint32_t bgp_med_value(struct attr *attr, struct bgp *bgp)
@@ -9407,14 +9416,16 @@ void route_vty_out(struct vty *vty, const struct prefix *p,
 	}
 
 	/* MED/Metric */
-	if (attr->flag & ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC))
+	if (use_bgp_med_value(attr, path->peer->bgp)) {
+		uint32_t value = bgp_med_value(attr, path->peer->bgp);
+
 		if (json_paths)
-			json_object_int_add(json_path, "metric", attr->med);
+			json_object_int_add(json_path, "metric", value);
 		else if (wide)
-			vty_out(vty, "%7u", attr->med);
+			vty_out(vty, "%7u", value);
 		else
-			vty_out(vty, "%10u", attr->med);
-	else if (!json_paths) {
+			vty_out(vty, "%10u", value);
+	} else if (!json_paths) {
 		if (wide)
 			vty_out(vty, "%*s", 7, " ");
 		else
@@ -9535,7 +9546,7 @@ void route_vty_out(struct vty *vty, const struct prefix *p,
 }
 
 /* called from terminal list command */
-void route_vty_out_tmp(struct vty *vty, struct bgp_dest *dest,
+void route_vty_out_tmp(struct vty *vty, struct bgp *bgp, struct bgp_dest *dest,
 		       const struct prefix *p, struct attr *attr, safi_t safi,
 		       bool use_json, json_object *json_ar, bool wide)
 {
@@ -9594,10 +9605,11 @@ void route_vty_out_tmp(struct vty *vty, struct bgp_dest *dest,
 					&attr->mp_nexthop_global_in);
 			}
 
-			if (attr->flag
-			    & ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC))
-				json_object_int_add(json_net, "metric",
-						    attr->med);
+			if (use_bgp_med_value(attr, bgp)) {
+				uint32_t value = bgp_med_value(attr, bgp);
+
+				json_object_int_add(json_net, "metric", value);
+			}
 
 			if (attr->flag & ATTR_FLAG_BIT(BGP_ATTR_LOCAL_PREF))
 				json_object_int_add(json_net, "locPrf",
@@ -9637,13 +9649,15 @@ void route_vty_out_tmp(struct vty *vty, struct bgp_dest *dest,
 				else
 					vty_out(vty, "%*s", len, " ");
 			}
-			if (attr->flag
-			    & ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC))
+
+			if (use_bgp_med_value(attr, bgp)) {
+				uint32_t value = bgp_med_value(attr, bgp);
+
 				if (wide)
-					vty_out(vty, "%7u", attr->med);
+					vty_out(vty, "%7u", value);
 				else
-					vty_out(vty, "%10u", attr->med);
-			else if (wide)
+					vty_out(vty, "%10u", value);
+			} else if (wide)
 				vty_out(vty, "       ");
 			else
 				vty_out(vty, "          ");
@@ -10640,11 +10654,13 @@ void route_vty_out_detail(struct vty *vty, struct bgp *bgp, struct bgp_dest *bn,
 		vty_out(vty, "      Origin %s",
 			bgp_origin_long_str[attr->origin]);
 
-	if (attr->flag & ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC)) {
+	if (use_bgp_med_value(attr, bgp)) {
+		uint32_t value = bgp_med_value(attr, bgp);
+
 		if (json_paths)
-			json_object_int_add(json_path, "metric", attr->med);
+			json_object_int_add(json_path, "metric", value);
 		else
-			vty_out(vty, ", metric %u", attr->med);
+			vty_out(vty, ", metric %u", value);
 	}
 
 	if (attr->flag & ATTR_FLAG_BIT(BGP_ATTR_LOCAL_PREF)) {
@@ -14288,7 +14304,7 @@ show_adj_route(struct vty *vty, struct peer *peer, struct bgp_table *table,
 							json_ar, json_net,
 							"%pFX", rn_p);
 				} else
-					route_vty_out_tmp(vty, dest, rn_p,
+					route_vty_out_tmp(vty, bgp, dest, rn_p,
 							  &attr, safi, use_json,
 							  json_ar, wide);
 				bgp_attr_flush(&attr);
@@ -14351,11 +14367,15 @@ show_adj_route(struct vty *vty, struct peer *peer, struct bgp_table *table,
 									"%pFX",
 									rn_p);
 						} else
-							route_vty_out_tmp(
-								vty, dest, rn_p,
-								&attr, safi,
-								use_json,
-								json_ar, wide);
+							route_vty_out_tmp(vty,
+									  bgp,
+									  dest,
+									  rn_p,
+									  &attr,
+									  safi,
+									  use_json,
+									  json_ar,
+									  wide);
 						(*output_count)++;
 					} else {
 						(*filtered_count)++;
@@ -14393,9 +14413,10 @@ show_adj_route(struct vty *vty, struct peer *peer, struct bgp_table *table,
 							json_ar, json_net,
 							"%pFX", rn_p);
 				} else
-					route_vty_out_tmp(
-						vty, dest, rn_p, pi->attr, safi,
-						use_json, json_ar, wide);
+					route_vty_out_tmp(vty, bgp, dest, rn_p,
+							  pi->attr, safi,
+							  use_json, json_ar,
+							  wide);
 				(*output_count)++;
 			}
 		}

diff --git a/bgpd/bgp_route.h b/bgpd/bgp_route.h
@@ -845,10 +845,10 @@ extern void route_vty_out(struct vty *vty, const struct prefix *p,
 extern void route_vty_out_tag(struct vty *vty, const struct prefix *p,
 			      struct bgp_path_info *path, int display,
 			      safi_t safi, json_object *json);
-extern void route_vty_out_tmp(struct vty *vty, struct bgp_dest *dest,
-			      const struct prefix *p, struct attr *attr,
-			      safi_t safi, bool use_json, json_object *json_ar,
-			      bool wide);
+extern void route_vty_out_tmp(struct vty *vty, struct bgp *bgp,
+			      struct bgp_dest *dest, const struct prefix *p,
+			      struct attr *attr, safi_t safi, bool use_json,
+			      json_object *json_ar, bool wide);
 extern void route_vty_out_overlay(struct vty *vty, const struct prefix *p,
 				  struct bgp_path_info *path, int display,
 				  json_object *json);

diff --git a/bgpd/bgp_updgrp_adv.c b/bgpd/bgp_updgrp_adv.c
@@ -328,15 +328,16 @@ static void subgrp_show_adjq_vty(struct update_subgroup *subgrp,
 			}
 			if ((flags & UPDWALK_FLAGS_ADVQUEUE) && adj->adv &&
 			    adj->adv->baa) {
-				route_vty_out_tmp(
-					vty, dest, dest_p, adj->adv->baa->attr,
-					SUBGRP_SAFI(subgrp), 0, NULL, false);
+				route_vty_out_tmp(vty, bgp, dest, dest_p,
+						  adj->adv->baa->attr,
+						  SUBGRP_SAFI(subgrp), 0, NULL,
+						  false);
 				output_count++;
 			}
 			if ((flags & UPDWALK_FLAGS_ADVERTISED) && adj->attr) {
-				route_vty_out_tmp(vty, dest, dest_p, adj->attr,
-						  SUBGRP_SAFI(subgrp), 0, NULL,
-						  false);
+				route_vty_out_tmp(vty, bgp, dest, dest_p,
+						  adj->attr, SUBGRP_SAFI(subgrp),
+						  0, NULL, false);
 				output_count++;
 			}
 		}

diff --git a/bgpd/bgp_vpn.c b/bgpd/bgp_vpn.c
@@ -191,7 +191,7 @@ int show_adj_route_vpn(struct vty *vty, struct peer *peer,
 				}
 				rd_header = 0;
 			}
-			route_vty_out_tmp(vty, rm, bgp_dest_get_prefix(rm),
+			route_vty_out_tmp(vty, bgp, rm, bgp_dest_get_prefix(rm),
 					  attr, safi, use_json, json_routes,
 					  false);
 			output_count++;

diff --git a/doc/user/bgp.rst b/doc/user/bgp.rst
@@ -425,6 +425,11 @@ Route Selection
 
    Disabled by default.
 
+.. clicmd:: bgp bestpath med missing-as-worst
+
+   If the paths MED value is missing and this command is configured
+   then treat it as the worse possible value that it can be.
+
 .. clicmd:: maximum-paths (1-128)
 
    Sets the maximum-paths value used for ecmp calculations for this