zones: add helpers to compose and parse wg0/wg1 addresses

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

pkg/zones/address.go

@@ -0,0 +1,49 @@
+package zones
+
+import "net/netip"
+
+// ParseRingZeroAddress extracts zone and node ID from a wg0 [netip.Addr]
+func ParseRingZeroAddress(addr netip.Addr) (zoneID int, nodeID int, ok bool) {
+	if addr.IsValid() {
+		a4 := addr.As4()
+
+		if a4[0] == 10 && a4[1] == 0 {
+			return int(a4[2]), int(a4[3]), true
+		}
+	}
+	return 0, 0, false
+}
+
+// RingZeroAddress returns a wg0 IP address
+func RingZeroAddress(zoneID, nodeID int) netip.Addr {
+	c := zoneID
+	d := nodeID
+
+	return netip.AddrFrom4([4]byte{
+		10, 0, uint8(c), uint8(d),
+	})
+}
+
+// ParseRingOneAddress extracts zone and node ID from a wg1 [netip.Addr]
+func ParseRingOneAddress(addr netip.Addr) (zoneID int, nodeID int, ok bool) {
+	if addr.IsValid() {
+		a4 := addr.As4()
+
+		if a4[0] == 10 && a4[2] == 0 {
+			zoneID = int(a4[1] >> 4)
+			nodeID = int(a4[3])
+			return zoneID, nodeID, true
+		}
+	}
+	return 0, 0, false
+}
+
+// RingOneAddress returns a wg1 IP address
+func RingOneAddress(zoneID, nodeID int) netip.Addr {
+	b := zoneID << 4
+	d := nodeID
+
+	return netip.AddrFrom4([4]byte{
+		10, uint8(b), 0, uint8(d),
+	})
+}