feat: Working impl with offer / ack

util.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"encoding/binary"
+	"net"
+)
+
+func int2ip(nn uint32) net.IP {
+	ip := make(net.IP, 4)
+	binary.BigEndian.PutUint32(ip, nn)
+	return ip
+}
+
+func u32tob(u uint32) []byte {
+	buf := make([]byte, 4)
+	binary.BigEndian.PutUint32(buf, u)
+	return buf
+}