From 46275b41edaa6063bdfb3ba040421b79ebd27b35 Mon Sep 17 00:00:00 2001
From: tv <tv@krebsco.de>
Date: Tue, 11 Dec 2018 21:37:52 +0100
Subject: [PATCH] lib.krebs.genipv6: can compute suffix from name
---
lib/krebs/genipv6.nix | 38 ++++++++++++++++++++++++++++++++++----
1 file changed, 34 insertions(+), 4 deletions(-)
diff --git a/lib/krebs/genipv6.nix b/lib/krebs/genipv6.nix
index 27df8bf55..8e105ab49 100644
--- a/lib/krebs/genipv6.nix
+++ b/lib/krebs/genipv6.nix
@@ -1,7 +1,7 @@
lib:
with lib;
let {
- body = netname: subnetname: suffix: rec {
+ body = netname: subnetname: suffixSpec: rec {
address = let
suffix' =
if hasEmptyGroup (parseAddress suffix)
@@ -28,15 +28,45 @@ let {
inherit subnetname;
subnetCIDR = "${subnetAddress}/${toString subnetPrefixLength}";
subnetAddress = joinAddress subnetPrefix "::";
- subnetHash = hash subnetname;
+ subnetHash = simplify (hash 4 subnetname);
subnetPrefix = joinAddress netPrefix subnetHash;
subnetPrefixLength = netPrefixLength + 16;
- inherit suffix;
+ suffix = getAttr (typeOf suffixSpec) {
+ set =
+ concatMapStringsSep
+ ":"
+ simplify
+ (stringToGroupsOf 4 (hash (suffixLength / 8) suffixSpec.hostName));
+ string = suffixSpec;
+ };
suffixLength = addressLength - subnetPrefixLength;
};
- hash = s: head (match "0*(.+)" (substring 0 4 (hashString "sha256" s)));
+ # Split string into list of chunks where each chunk is at most n chars long.
+ # The leftmost chunk might shorter.
+ # Example: stringToGroupsOf "123456" -> ["12" "3456"]
+ stringToGroupsOf = n: s: let
+ acc =
+ foldl'
+ (acc: c: if stringLength acc.chunk < n then {
+ chunk = acc.chunk + c;
+ chunks = acc.chunks;
+ } else {
+ chunk = c;
+ chunks = acc.chunks ++ [acc.chunk];
+ })
+ {
+ chunk = "";
+ chunks = [];
+ }
+ (stringToCharacters s);
+ in
+ filter (x: x != []) ([acc.chunk] ++ acc.chunks);
+
+ simplify = s: head (match "0*(.+)" s);
+
+ hash = n: s: substring 0 n (hashString "sha256" s);
dropLast = n: xs: reverseList (drop n (reverseList xs));
takeLast = n: xs: reverseList (take n (reverseList xs));