From 05a5979906ef181644ee4db71bcbbd90ca7c8cca Mon Sep 17 00:00:00 2001
From: Ihar Hrachyshka <ihar.hrachyshka@gmail.com>
Date: Sun, 10 Aug 2025 21:19:51 -0400
Subject: [PATCH] networking: add dhcpClientId option to set DHCP Client ID

---
 modules/networking/default.nix                | 19 +++++++++++++++++++
 release.nix                                   |  1 +
 ...king-networkservices-no-dhcp-client-id.nix | 14 ++++++++++++++
 tests/networking-networkservices.nix          |  3 +++
 4 files changed, 37 insertions(+)
 create mode 100644 tests/networking-networkservices-no-dhcp-client-id.nix

diff --git a/modules/networking/default.nix b/modules/networking/default.nix
index e75e234..44af42e 100644
--- a/modules/networking/default.nix
+++ b/modules/networking/default.nix
@@ -18,6 +18,9 @@ let
         *${lib.escapeShellArg srv}*)
           networksetup -setdnsservers ${lib.escapeShellArgs ([ srv ] ++ (emptyList cfg.dns))}
           networksetup -setsearchdomains ${lib.escapeShellArgs ([ srv ] ++ (emptyList cfg.search))}
+          ${optionalString (cfg.dhcpClientId != null) ''
+            networksetup -setdhcp ${lib.escapeShellArgs [ srv cfg.dhcpClientId ]}
+          ''}
           ;;
       esac
     '') cfg.knownNetworkServices}
@@ -133,6 +136,21 @@ in
       '';
     };
 
+    networking.dhcpClientId = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      example = "my-client-id";
+      description = ''
+        The DHCP client identifier to use when requesting an IP address from a DHCP server.
+
+        If this option is set, it will be used by the system when requesting an IP address.
+        If not set, no changes will be made.
+
+        Set to the string "empty" to clear any previously configured client ID
+        and restore the system default behavior.
+      '';
+    };
+
     networking.dns = mkOption {
       type = types.listOf types.str;
       default = [];
@@ -162,6 +180,7 @@ in
     warnings = [
       (mkIf (cfg.knownNetworkServices == [] && cfg.dns != []) "networking.knownNetworkServices is empty, dns servers will not be configured.")
       (mkIf (cfg.knownNetworkServices == [] && cfg.search != []) "networking.knownNetworkServices is empty, dns searchdomains will not be configured.")
+      (mkIf (cfg.knownNetworkServices == [] && cfg.dhcpClientId != null) "networking.knownNetworkServices is empty, dhcp client ID will not be configured.")
     ];
 
     system.activationScripts.networking.text = ''
diff --git a/release.nix b/release.nix
index 160c642..b8a1d6b 100644
--- a/release.nix
+++ b/release.nix
@@ -88,6 +88,7 @@ in {
   tests.networking-firewall = makeTest ./tests/networking-firewall.nix;
   tests.networking-hostname = makeTest ./tests/networking-hostname.nix;
   tests.networking-networkservices = makeTest ./tests/networking-networkservices.nix;
+  tests.networking-networkservices-no-dhcp-client-id = makeTest ./tests/networking-networkservices-no-dhcp-client-id.nix;
   tests.nix-enable = makeTest ./tests/nix-enable.nix;
   tests.nixpkgs-overlays = makeTest ./tests/nixpkgs-overlays.nix;
   tests.programs-gnupg = makeTest ./tests/programs-gnupg.nix;
diff --git a/tests/networking-networkservices-no-dhcp-client-id.nix b/tests/networking-networkservices-no-dhcp-client-id.nix
new file mode 100644
index 0000000..2a37425
--- /dev/null
+++ b/tests/networking-networkservices-no-dhcp-client-id.nix
@@ -0,0 +1,14 @@
+{ config, lib, ... }:
+
+{
+  networking.knownNetworkServices = [ "Wi-Fi" "Thunderbolt Ethernet" ];
+  networking.dns = [ "8.8.8.8" "8.8.4.4" ];
+
+  test = ''
+    echo checking dhcp client ID is not configured in /activate >&2
+    if grep -q "networksetup -setdhcp" ${config.out}/activate; then
+      echo "unexpected dhcp client ID configuration in /activate" >&2
+      exit 1
+    fi
+  '';
+}
diff --git a/tests/networking-networkservices.nix b/tests/networking-networkservices.nix
index a657342..7e6f744 100644
--- a/tests/networking-networkservices.nix
+++ b/tests/networking-networkservices.nix
@@ -3,11 +3,14 @@
 {
   networking.knownNetworkServices = [ "Wi-Fi" "Thunderbolt Ethernet" ];
   networking.dns = [ "8.8.8.8" "8.8.4.4" ];
+  networking.dhcpClientId = "test-client-id";
 
   test = ''
     echo checking dns settings in /activate >&2
     grep "networksetup -setdnsservers ${lib.escapeShellArgs [ "Wi-Fi" "8.8.8.8" "8.8.4.4" ]}" ${config.out}/activate
     grep "networksetup -setdnsservers ${lib.escapeShellArgs [ "Thunderbolt Ethernet" "8.8.8.8" "8.8.4.4" ]}" ${config.out}/activate
+    grep "networksetup -setdhcp ${lib.escapeShellArgs [ "Wi-Fi" "test-client-id" ]}" ${config.out}/activate
+    grep "networksetup -setdhcp ${lib.escapeShellArgs [ "Thunderbolt Ethernet" "test-client-id" ]}" ${config.out}/activate
     echo checking empty searchdomain settings in /activate >&2
     grep "networksetup -setsearchdomains ${lib.escapeShellArgs [ "Wi-Fi" "empty" ]}" ${config.out}/activate
     grep "networksetup -setsearchdomains ${lib.escapeShellArgs [ "Thunderbolt Ethernet" "empty" ]}" ${config.out}/activate