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rings: RingOnePrefix()/RingOneAddress()

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Ring one designates the (virtual) local network of a zone
within a region.

Signed-off-by: Alejandro Mery <amery@jpi.io>
This commit is contained in:
Alejandro Mery
2024-05-25 21:22:33 +00:00
parent a4276c9907
commit 01fd2f35a3
2 changed files with 106 additions and 0 deletions
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pkg/rings/rings.go
+52
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@@ -3,6 +3,7 @@
package rings
import (
"net/netip"
"syscall"
"darvaza.org/core"
@@ -18,6 +19,9 @@ const (
// NodeZeroMax indicates the highest number that can be used for a [NodeID]
// when its a gateway connected to Ring 0 (backbone).
NodeZeroMax = (1 << 8) - 1
// RingOneBits indicates the size of the prefix on the ring 1 (lan) network.
RingOneBits = 20
)
// RegionID is the identifier of a region, valid between 1 and [RegionMax].
@@ -47,3 +51,51 @@ func (n NodeID) ValidZero() bool { return n > 0 && n <= NodeZeroMax }
func ErrOutOfRange[T ~int | ~uint32](value T, field string) error {
return core.Wrap(syscall.EINVAL, "%s out of range (%v)", field, value)
}
// RingOnePrefix represents a (virtual) local network of a zone.
//
// Ring 1 is `10.(region_id).(zone_id << 4).(node_id)/20` network
// grouped under what would be Ring 2 for region_id 0.
// There are 12 bits worth of nodes but nodes under 255 are special
// as they also get a slot on Ring 0.
func RingOnePrefix(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 := unsafeRingOneAddress(region, zone, 0)
cidr = netip.PrefixFrom(addr, RingOneBits)
}
return cidr, err
}
// RingOneAddress returns a Ring 1 address for a particular node.
//
// A ring 1 address is `10.(region_id).(zone_id << 4).(node_id)/20`
// but the node_id can take up to 12 bits.
func RingOneAddress(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.Valid():
err = ErrOutOfRange(node, "node")
default:
addr = unsafeRingOneAddress(region, zone, node)
}
return addr, err
}
func unsafeRingOneAddress(region RegionID, zone ZoneID, node NodeID) netip.Addr {
r := uint(region)
z := uint(zone)
n := uint(node)
n1 := n >> 8
n0 := n >> 0
return AddrFrom4(10, r, z<<4+n1, n0)
}