From 5a06ab74bbbf2f119c5b388b1544442b18b76d19 Mon Sep 17 00:00:00 2001
From: Bruno BELANYI <bruno@belanyi.fr>
Date: Sat, 24 Apr 2021 23:08:43 +0000
Subject: [PATCH] lib: ip: add 'nth' utility to 'parseSubnet4'

---
 lib/ip.nix | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/lib/ip.nix b/lib/ip.nix
index f499072..40c40c0 100644
--- a/lib/ip.nix
+++ b/lib/ip.nix
@@ -75,9 +75,22 @@ rec {
             "which will get masked to ${prettyIp4 baseIp},"
             "which should be used instead"
           ]);
+      nth = n:
+        let
+          result = nthInRange4 range n;
+          try =
+            if check result
+            then id
+            else
+              warn (concatStringsSep " " [
+                "nth call with n = ${toString n}"
+                "is out of range for subnet ${str}"
+              ]);
+        in
+        try result;
     in
     try {
-      inherit baseIp check cidr mask range;
+      inherit baseIp check cidr mask nth range;
     };
 
   # Pretty print a parsed IPv4 address into a human readable form