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Fix assign{Ips,Macs} #2

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Fix assign{Ips,Macs} #2

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e81b403
Fix flip import
GeoffreyFrogeye Apr 7, 2025
9eaab91
assign{Ips,Macs}: Fix integer overflow
GeoffreyFrogeye Apr 7, 2025
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15 changes: 9 additions & 6 deletions nix/net-extensions.nix
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@ let
;

inherit (lib.trivial)
flip
min
warnIf
;
Expand All @@ -35,10 +36,6 @@ let
assertMsg
;

inherit (lib.debug)
flip
;

# NOTE: from <https://github.com/oddlama/nixos-extra-modules/blob/ba53e1a0becde25b0644fbf886234669c9b285e3/lib/misc.nix>

# Calculates base^exp, but careful, this overflows for results > 2^62
Expand Down Expand Up @@ -242,6 +239,8 @@ in {
#
# > net.cidr.assignIps "192.168.100.1/24" [202 "192.168.100.74"] ["a" "b" "c"]
# { a = "192.168.100.203"; b = "192.168.100.75"; c = "192.168.100.226"; }
#
# WARN: Does not work on IPv6 addresses with Lix 2.91+ and Nix.25+ as they ban integer overflow.
assignIps = net: reserved: hosts: let
cidrSize = libNet.cidr.size net;
capacity = libNet.cidr.capacity net;
Expand Down Expand Up @@ -269,7 +268,8 @@ in {
# Generates a hash (i.e. offset value) for a given hostname
hashElem = x:
builtins.bitAnd (capacity - 1)
(hexToDec (builtins.substring 0 16 (builtins.hashString "sha256" x)));
# 15 characters is as many hexToDec can handle (60 bits)
(hexToDec (builtins.substring 0 15 (builtins.hashString "sha256" x)));
# Do linear probing. Returns the first unused value at or after the given value.
probe = avoid: value:
if elem value avoid
Expand Down Expand Up @@ -336,6 +336,8 @@ in {
#
# > net.mac.assignMacs "11:22:33:00:00:00" 24 ["11:22:33:1b:bd:ca"] ["a" "b" "c"]
# { a = "11:22:33:1b:bd:cb"; b = "11:22:33:39:59:4a"; c = "11:22:33:50:7a:e2"; }
#
# WARN: Does not work with Lix 2.91+ and Nix.25+ as they ban integer overflow.
assignMacs = base: size: reserved: hosts: let
capacity = pow 2 size;
baseAsInt = libNet.mac.diff base "00:00:00:00:00:00";
Expand All @@ -356,7 +358,8 @@ in {
# Generates a hash (i.e. offset value) for a given hostname
hashElem = x:
builtins.bitAnd (capacity - 1)
(hexToDec (substring 0 16 (builtins.hashString "sha256" x)));
# 15 characters is as many hexToDec can handle (60 bits)
(hexToDec (substring 0 15 (builtins.hashString "sha256" x)));
# Do linear probing. Returns the first unused value at or after the given value.
probe = avoid: value:
if elem value avoid
Expand Down