rings: RingZeroPrefix()/RingZeroAddress()

Ring zero corresponds to the backbone that connects all zones.

Signed-off-by: Alejandro Mery <amery@jpi.io>

pkg/rings/rings.go

@@ -19,6 +19,8 @@ const (
 	// when its a gateway connected to Ring 0 (backbone).
 	NodeZeroMax = (1 << 8) - 1
 
+	// RingZeroBits indicates the size of the prefix on the ring 0 (backbone) network.
+	RingZeroBits = 16
 	// RingOneBits indicates the size of the prefix on the ring 1 (lan) network.
 	RingOneBits = 20
 )

pkg/rings/zero.go

@@ -0,0 +1,40 @@
+package rings
+
+import "net/netip"
+
+// RingZeroPrefix represents the backbone that connects gateways
+// of the different Ring 1 networks.
+//
+// The ring 0 network corresponds to what would be ring 2 for region_id 0.
+// 10.0.0.0-10.0.255.255
+func RingZeroPrefix(region RegionID, zone ZoneID) (cidr netip.Prefix, err error) {
+	switch {
+	case !region.Valid():
+		err = ErrOutOfRange(region, "region")
+	case !zone.Valid():
+		err = ErrOutOfRange(zone, "zone")
+	default:
+		addr := AddrFrom4(10, 0, uint(region)<<4+uint(zone), 0)
+		cidr = netip.PrefixFrom(addr, RingZeroBits)
+	}
+
+	return cidr, err
+}
+
+// RingZeroAddress returns a Ring 0 address for a particular node.
+//
+// A ring 0 address looks like 10.0.(region_id << 4 + zone_id).(node_id)/20
+func RingZeroAddress(region RegionID, zone ZoneID, node NodeID) (addr netip.Addr, err error) {
+	switch {
+	case !region.Valid():
+		err = ErrOutOfRange(region, "region")
+	case !zone.Valid():
+		err = ErrOutOfRange(zone, "zone")
+	case !node.ValidZero():
+		err = ErrOutOfRange(node, "node")
+	default:
+		addr = AddrFrom4(10, 0, uint(region)<<4+uint(zone), uint(node))
+	}
+
+	return addr, err
+}