Fix mkReverseRecord for ::1 and 1:: being twice as long

Author: SuperSandro2000

dns/util/default.nix

@@ -37,7 +37,13 @@ let
   # Returns the record of the ipv6 as a list
   mkRecordAux = v6:
     let
-      splitted = lib.splitString ":" v6;
+      v6' = if lib.hasPrefix "::" v6 then
+        "0${v6}"
+      else if lib.hasSuffix "::" v6 then
+        "${v6}0"
+      else
+        v6;
+      splitted = lib.splitString ":" v6';
       n = 8 - builtins.length (lib.filter (x: x != "") splitted);
     in
       lib.stringToCharacters (lib.concatMapStrings (align4BytesOrExpand n) splitted);