Merge branch 'pr-amery-regions' into next-amery

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

pkg/rings/decode.go

@@ -0,0 +1,74 @@
+package rings
+
+import (
+	"net/netip"
+)
+
+// DecodeAddress extracts ring address fields from a given 10.0.0.0/8
+// address.
+//
+// revive:disable:function-result-limit
+func DecodeAddress[T ~uint | NodeID](addr netip.Addr) (RingID, RegionID, ZoneID, T) {
+	// revive:enable:function-result-limit
+	if addr.IsValid() {
+		if addr.Is4In6() {
+			addr = addr.Unmap()
+		}
+
+		if addr.Is4() {
+			a4 := addr.As4()
+			return unsafeDecodeAddress[T](a4[0], a4[1], a4[2], a4[3])
+		}
+	}
+
+	return UnspecifiedRingID, 0, 0, 0
+}
+
+// revive:disable:function-result-limit
+func unsafeDecodeAddress[T ~uint | NodeID](a, b, c, d byte) (RingID, RegionID, ZoneID, T) {
+	// revive:enable:function-result-limit
+	switch {
+	case a != 10:
+		return UnspecifiedRingID, 0, 0, 0
+	case b == 0x00:
+		// 10.00.RZ.dd
+		k := RingZeroID
+		r := RegionID(c >> 4)
+		z := ZoneID(c & 0xf)
+		n := T(d)
+
+		return k, r, z, n
+	case b&0xf0 != 0:
+		// 10.Rb.cc.dd
+		k := RingThreeID
+		r := RegionID(b >> 4)
+
+		n2 := T(b & 0x0f)
+		n1 := T(c)
+		n0 := T(d)
+		n := n0 + n1<<8 + n2<<16
+
+		return k, r, 0, n
+	case c&0xf0 != 0:
+		// 10.0R.Zc.dd
+		k := RingOneID
+		r := RegionID(b)
+		z := ZoneID(c >> 4)
+
+		n1 := T(c & 0x0f)
+		n0 := T(d)
+		n := n0 + n1<<8
+
+		return k, r, z, n
+	default:
+		// 10.0R.0c.dd
+		k := RingTwoID
+		r := RegionID(b)
+
+		n1 := T(c & 0x0f)
+		n0 := T(d)
+		n := n0 + n1<<8
+
+		return k, r, 0, n
+	}
+}

pkg/rings/rings.go

@@ -11,6 +11,17 @@ import (
 )
 
 const (
+	// UnspecifiedRingID is the zero value of RingID and not considered
+	// valid.
+	UnspecifiedRingID RingID = iota
+	RingZeroID               // RingZeroID is the RingID for RingZero (backbone)
+	RingOneID                // RingOneID is the RingID for RingOne (local zone)
+	RingTwoID                // RingTwoID is the RingID for RingTwo (region services)
+	RingThreeID              // RingThreeID is the RingID for RingThree (region cluster pods)
+
+	// RingMax indicates the highest [Ring] identifier
+	RingMax = RingThreeID
+
 	// RegionMax indicates the highest number that can be used for a [RegionID].
 	RegionMax = (1 << 4) - 1
 	// ZoneMax indicates the highest number that can be used for a [ZoneID].
@@ -33,6 +44,21 @@ const (
 	RingThreeBits = 12
 )
 
+// RingID identifies a Ring
+type RingID int
+
+// Valid tells a [RingID] is within the valid range.
+func (n RingID) Valid() bool { return n > 0 && n <= RingMax }
+
+func (n RingID) String() string {
+	return idString(n)
+}
+
+// A Ring identifies what ring an address belongs to
+type Ring interface {
+	ID() RingID
+}
+
 // RegionID is the identifier of a region, valid between 1 and [RegionMax].
 type RegionID int