create DB struct

This is step one in detaching the Database layer from Headscale (h). The
ultimate goal is to have all function that does database operations in
its own package, and keep the business logic and writing separate.

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

hscontrol/util/addr.go

@@ -0,0 +1,42 @@
+package util
+
+import (
+	"net/netip"
+	"reflect"
+
+	"go4.org/netipx"
+)
+
+func GetIPPrefixEndpoints(na netip.Prefix) (netip.Addr, netip.Addr) {
+	var network, broadcast netip.Addr
+	ipRange := netipx.RangeOfPrefix(na)
+	network = ipRange.From()
+	broadcast = ipRange.To()
+
+	return network, broadcast
+}
+
+func StringToIPPrefix(prefixes []string) ([]netip.Prefix, error) {
+	result := make([]netip.Prefix, len(prefixes))
+
+	for index, prefixStr := range prefixes {
+		prefix, err := netip.ParsePrefix(prefixStr)
+		if err != nil {
+			return []netip.Prefix{}, err
+		}
+
+		result[index] = prefix
+	}
+
+	return result, nil
+}
+
+func StringOrPrefixListContains[T string | netip.Prefix](ts []T, t T) bool {
+	for _, v := range ts {
+		if reflect.DeepEqual(v, t) {
+			return true
+		}
+	}
+
+	return false
+}