From ac4bfcc965cdfac64b563874529a2b8135663e47 Mon Sep 17 00:00:00 2001
From: Christoph Heiss <christoph@c8h4.io>
Date: Sat, 21 Dec 2024 16:31:11 +0100
Subject: [PATCH] nixos/initrd-network: add option for enabling udhcpc6 support

Currently, having stage1 get an IPv6 address from a DHCPv6 server is not
possible, which esp. presents itself as an problem in IPv6
networks/deployments.

Signed-off-by: Christoph Heiss <christoph@c8h4.io>
---
 nixos/modules/system/boot/initrd-network.nix | 38 ++++++++++++++++++--
 1 file changed, 35 insertions(+), 3 deletions(-)

diff --git a/nixos/modules/system/boot/initrd-network.nix b/nixos/modules/system/boot/initrd-network.nix
index 17929761936726..9b7ebf6aa7a5cf 100644
--- a/nixos/modules/system/boot/initrd-network.nix
+++ b/nixos/modules/system/boot/initrd-network.nix
@@ -15,8 +15,9 @@ let
     lib.filterAttrs (iface: v: v.useDHCP == true) (config.networking.interfaces or { })
   );
   doDhcp = cfg.udhcpc.enable || dhcpInterfaces != [ ];
+  doDhcp6 = cfg.udhcpc6.enable || dhcpInterfaces != [ ];
   dhcpIfShellExpr =
-    if config.networking.useDHCP || cfg.udhcpc.enable then
+    if config.networking.useDHCP || cfg.udhcpc.enable || cfg.udhcpc6.enable then
       "$(ls /sys/class/net/ | grep -v ^lo$)"
     else
       lib.concatMapStringsSep " " lib.escapeShellArg dhcpInterfaces;
@@ -48,6 +49,7 @@ let
   '';
 
   udhcpcArgs = toString cfg.udhcpc.extraArgs;
+  udhcpc6Args = toString cfg.udhcpc6.extraArgs;
 
 in
 
@@ -108,6 +110,25 @@ in
       '';
     };
 
+    boot.initrd.network.udhcpc6.enable = mkOption {
+      default = false;
+      type = types.bool;
+      description = ''
+        Enables the udhcpc6 service during stage 1 of the boot process. This
+        defaults to `false`.
+      '';
+    };
+
+    boot.initrd.network.udhcpc6.extraArgs = mkOption {
+      default = [ ];
+      type = types.listOf types.str;
+      description = ''
+        Additional command-line arguments passed verbatim to udhcpc6 if
+        {option}`boot.initrd.network.enable` and
+        {option}`boot.initrd.network.udhcpc6.enable` are enabled.
+      '';
+    };
+
     boot.initrd.network.postCommands = mkOption {
       default = "";
       type = types.lines;
@@ -141,14 +162,16 @@ in
           done
         ''
 
-        # Otherwise, use DHCP.
-        + optionalString doDhcp ''
+        + optionalString (doDhcp || doDhcp6) ''
           # Bring up all interfaces.
           for iface in ${dhcpIfShellExpr}; do
             echo "bringing up network interface $iface..."
             ip link set dev "$iface" up && ifaces="$ifaces $iface"
           done
+        ''
 
+        # Otherwise, use DHCP ..
+        + optionalString doDhcp ''
           # Acquire DHCP leases.
           for iface in ${dhcpIfShellExpr}; do
             echo "acquiring IP address via DHCP on $iface..."
@@ -156,6 +179,15 @@ in
           done
         ''
 
+        # .. and/or DHCPv6
+        + optionalString doDhcp6 ''
+          # Acquire DHCP leases.
+          for iface in ${dhcpIfShellExpr}; do
+            echo "acquiring IP address via DHCP on $iface..."
+            udhcpc6 --quit --now -i $iface --script ${udhcpcScript} ${udhcpc6Args}
+          done
+        ''
+
         + cfg.postCommands
       )
     );