24-keepalive-holepunch

Added the ability to hole punch NAT

pkg/lib/hashing.go

@@ -0,0 +1,46 @@
+package lib
+
+import (
+	"hash/fnv"
+	"sort"
+)
+
+type consistentHashRecord[V any] struct {
+	record V
+	value  int
+}
+
+func HashString(value string) int {
+	f := fnv.New32a()
+	f.Write([]byte(value))
+	return int(f.Sum32())
+}
+
+// ConsistentHash implementation. Traverse the values until we find a key
+// less than ours.
+func ConsistentHash[V any](values []V, client V, keyFunc func(V) int) V {
+	if len(values) == 0 {
+		panic("values is empty")
+	}
+
+	vs := Map(values, func(v V) consistentHashRecord[V] {
+		return consistentHashRecord[V]{
+			v,
+			keyFunc(v),
+		}
+	})
+
+	sort.SliceStable(vs, func(i, j int) bool {
+		return vs[i].value < vs[j].value
+	})
+
+	ourKey := keyFunc(client)
+
+	for _, record := range vs {
+		if ourKey < record.value {
+			return record.record
+		}
+	}
+
+	return vs[0].record
+}