From 073a8ae3b34ed85619dd22bba0d4fb6b6e8e14d1 Mon Sep 17 00:00:00 2001
From: oddlama <oddlama@oddlama.org>
Date: Fri, 22 Dec 2023 01:47:12 +0100
Subject: [PATCH] feat: add interface naming module

---
 flake.nix                    |  2 +-
 modules/default.nix          |  6 ++++-
 modules/interface-naming.nix | 50 ++++++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+), 2 deletions(-)
 create mode 100644 modules/interface-naming.nix

diff --git a/flake.nix b/flake.nix
index d3022ad..ed1eec0 100644
--- a/flake.nix
+++ b/flake.nix
@@ -25,7 +25,7 @@
     ...
   }:
     {
-      nixosModules.extra-modules = import ./modules nixpkgs;
+      nixosModules.extra-modules = import ./modules;
       nixosModules.default = self.nixosModules.extra-modules;
     }
     // flake-utils.lib.eachDefaultSystem (system: rec {
diff --git a/modules/default.nix b/modules/default.nix
index 0967ef4..0b4b850 100644
--- a/modules/default.nix
+++ b/modules/default.nix
@@ -1 +1,5 @@
-{}
+{
+  imports = [
+    ./interface-naming.nix
+  ];
+}
diff --git a/modules/interface-naming.nix b/modules/interface-naming.nix
new file mode 100644
index 0000000..64ca85b
--- /dev/null
+++ b/modules/interface-naming.nix
@@ -0,0 +1,50 @@
+# Provides an option to easily rename interfaces by their mac addresses.
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}: let
+  inherit
+    (lib)
+    attrValues
+    concatStringsSep
+    duplicates
+    flip
+    mapAttrsToList
+    mkOption
+    types
+    ;
+
+  cfg = config.networking.renameInterfacesByMac;
+
+  interfaceNamesUdevRules = pkgs.writeTextFile {
+    name = "interface-names-udev-rules";
+    text = concatStringsSep "\n" (
+      flip mapAttrsToList cfg
+      (name: mac: ''SUBSYSTEM=="net", ACTION=="add", ATTR{address}=="${mac}", NAME:="${name}"'')
+    );
+    destination = "/etc/udev/rules.d/01-interface-names.rules";
+  };
+in {
+  options.networking.renameInterfacesByMac = mkOption {
+    default = {};
+    example = {lan = "11:22:33:44:55:66";};
+    description = "Allows naming of network interfaces based on their physical address";
+    type = types.attrsOf types.str;
+  };
+
+  config = lib.mkIf (cfg != {}) {
+    assertions = let
+      duplicateMacs = duplicates (attrValues cfg);
+    in [
+      {
+        assertion = duplicateMacs == [];
+        message = "Duplicate mac addresses found in network interface name assignment: ${concatStringsSep ", " duplicateMacs}";
+      }
+    ];
+
+    services.udev.packages = [interfaceNamesUdevRules];
+    boot.initrd.services.udev.packages = [interfaceNamesUdevRules];
+  };
+}