cs: fix beacon metadata core x-over, validate config

Fix the intra-AS metadata included for cross-over from up-segments
to core-segments, to match the documented scheme (see scionproto#3963).
Concretely, the core segments now contain no data for cross-over.
Instead, the up/down segments now contain cross-over information to
_all_ core interfaces (previously only a subset).
Previously, core-segments were handled just like down segments, without
taking into account that cross-over to the _ingress_ interface of the
core-segment beacon also needs to be ensured; consequently, the data for
the cross-over between the up- and core-segment was missing.

Also, add some validation/convenience functionality for the
configuration read from the staticInfoConfig.json file. Specifically,
this extends missing information from the "Intra" sections to be
symmetric (symmetry is an assumption of the system).

Closes scionproto#3972

GitOrigin-RevId: d1cea6572623ea0f63ace7b7a9fc777dcf43d0ba

go/cs/beaconing/staticinfo_config.go

@@ -99,12 +99,104 @@ func ParseStaticInfoCfg(file string) (*StaticInfoCfg, error) {
 		return nil, serrors.WrapStr("failed to parse static info config: ",
 			err, "file ", file)
 	}
-	// TODO(matzf): validate that there are no entries for 0 the interface ID.
-	// TODO(matzf): the interface-to-interface ("Intra") entries in the json file
-	// are (expected to be!) symmetric. Check & fill in the symmetric entries.
+	cfg.clean()
 	return &cfg, nil
 }
 
+// clean checks or corrects the entries in the static info configuration.
+// In particular, it will
+//  - ensure there are no entries for the 0 interface ID (as this is invalid
+//    and the beacon extender code uses 0 as the interface number for
+//    originating/terminating beacons), and
+//  - ensure the symmetry of the interface-to-interface ("Intra") entries,
+//    allowing to specify them in only one direction.
+func (cfg *StaticInfoCfg) clean() {
+
+	delete(cfg.Latency, 0)
+	for _, s := range cfg.Latency {
+		delete(s.Intra, 0)
+	}
+	delete(cfg.Bandwidth, 0)
+	for _, s := range cfg.Bandwidth {
+		delete(s.Intra, 0)
+	}
+	delete(cfg.LinkType, 0)
+	delete(cfg.Geo, 0)
+	delete(cfg.Hops, 0)
+	for _, s := range cfg.Hops {
+		delete(s.Intra, 0)
+	}
+
+	symmetrizeLatency(cfg.Latency)
+	symmetrizeBandwidth(cfg.Bandwidth)
+	symmetrizeHops(cfg.Hops)
+}
+
+// symmetrizeLatency makes the Intra latency values symmetric
+func symmetrizeLatency(latency map[common.IFIDType]InterfaceLatencies) {
+	for i, sub := range latency {
+		delete(sub.Intra, i) // Remove loopy entry
+		for j, v := range sub.Intra {
+			if _, ok := latency[j]; !ok {
+				continue
+			}
+			if latency[j].Intra == nil {
+				latency[j] = InterfaceLatencies{
+					Inter: latency[j].Inter,
+					Intra: make(map[common.IFIDType]util.DurWrap),
+				}
+			}
+			vTransposed, ok := latency[j].Intra[i]
+			// Set if not specified or pick more conservative value if both are specified
+			if !ok || v.Duration > vTransposed.Duration {
+				latency[j].Intra[i] = v
+			}
+		}
+	}
+}
+
+// symmetrizeBandwidth makes the Intra bandwidth values symmetric
+func symmetrizeBandwidth(bandwidth map[common.IFIDType]InterfaceBandwidths) {
+	for i, sub := range bandwidth {
+		delete(sub.Intra, i) // Remove loopy entry
+		for j, v := range sub.Intra {
+			if _, ok := bandwidth[j]; !ok {
+				continue
+			}
+			if bandwidth[j].Intra == nil {
+				bandwidth[j] = InterfaceBandwidths{
+					Inter: bandwidth[j].Inter,
+					Intra: make(map[common.IFIDType]uint64),
+				}
+			}
+			vTransposed, ok := bandwidth[j].Intra[i]
+			// Set if not specified or pick more conservative value if both are specified
+			if !ok || v < vTransposed {
+				bandwidth[j].Intra[i] = v
+			}
+		}
+	}
+}
+
+// symmetrizeHops makes the Intra hops values symmetric
+func symmetrizeHops(hops map[common.IFIDType]InterfaceHops) {
+	for i, sub := range hops {
+		delete(sub.Intra, i) // Remove loopy entry
+		for j, v := range sub.Intra {
+			if _, ok := hops[j]; !ok {
+				hops[j] = InterfaceHops{
+					Intra: make(map[common.IFIDType]uint32),
+				}
+			}
+			vTransposed, ok := hops[j].Intra[i]
+			// Set if not specified or pick more conservative value if both are specified
+			if !ok || v < vTransposed {
+				hops[j].Intra[i] = v
+			}
+		}
+	}
+}
+
 // Generate creates a StaticInfoExtn struct and
 // populates it with data extracted from the configuration.
 func (cfg StaticInfoCfg) Generate(intfs *ifstate.Interfaces,
@@ -240,10 +332,16 @@ func (cfg StaticInfoCfg) generateGeo(ifType map[common.IFIDType]topology.LinkTyp
 func includeIntraInfo(ifType map[common.IFIDType]topology.LinkType,
 	ifid, ingress, egress common.IFIDType) bool {
 
+	isCoreIngress := (ifType[ingress] == topology.Core || ingress == 0)
+	isCoreEgress := (ifType[egress] == topology.Core || egress == 0)
+	isCoreSeg := isCoreIngress && isCoreEgress
+	if isCoreSeg {
+		return ifid == ingress
+	}
 	t := ifType[ifid]
 	return ifid == ingress ||
 		t == topology.Child && ifid > egress ||
-		t == topology.Core && (egress == 0 || ingress == 0) && ifid > egress ||
+		t == topology.Core ||
 		t == topology.Peer
 }