zones: introduce ValidZoneID() and ValidNodeID()

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

pkg/zones/address.go

@@ -1,49 +0,0 @@
-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),
-	})
-}

pkg/zones/rings.go

@@ -0,0 +1,84 @@
+package zones
+
+import "net/netip"
+
+const (
+	// MaxZoneID indicates the highest ID allowed for a Zone
+	MaxZoneID = 0xf
+	// MaxNodeID indicates the highest Machine ID allowed within a Zone
+	MaxNodeID = 0xff - 1
+)
+
+// ValidZoneID checks if the given zoneID is a valid 4 bit zone number.
+//
+// 0 is reserved, and only allowed when composing CIDRs.
+func ValidZoneID(zoneID int) bool {
+	switch {
+	case zoneID < 0 || zoneID > MaxZoneID:
+		return false
+	default:
+		return true
+	}
+}
+
+// ValidNodeID checks if the given nodeID is a valid 8 bit number.
+// nodeID is unique within a Zone.
+// 0 is reserved, and only allowed when composing CIDRs.
+func ValidNodeID(nodeID int) bool {
+	switch {
+	case nodeID < 0 || nodeID > MaxNodeID:
+		return false
+	default:
+		return true
+	}
+}
+
+// ParseRingZeroAddress extracts zone and node ID from a wg0 [netip.Addr]
+// wg0 addresses are of the form `10.0.{{zoneID}}.{{nodeID}}`
+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, bool) {
+	switch {
+	case !ValidZoneID(zoneID) || !ValidNodeID(nodeID):
+		return netip.Addr{}, false
+	default:
+		a4 := [4]uint8{10, 0, uint8(zoneID), uint8(nodeID)}
+		return netip.AddrFrom4(a4), true
+	}
+}
+
+// ParseRingOneAddress extracts zone and node ID from a wg1 [netip.Addr]
+// wg1 addresses are of the form `10.{{zoneID << 4}}.{{nodeID}}`
+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, bool) {
+	switch {
+	case !ValidZoneID(zoneID) || !ValidNodeID(nodeID):
+		return netip.Addr{}, false
+	default:
+		a4 := [4]uint8{10, 0, uint8(zoneID << 4), uint8(nodeID)}
+		return netip.AddrFrom4(a4), true
+	}
+}