{
  liminix
, busybox
, writeShellScript
, serviceFns
} :
let
  inherit (liminix.services) longrun;
in
interface: { ... } @ args:
let
  name = "${interface.device}.udhcp";
  script = writeShellScript "udhcp-notify" ''
    . ${serviceFns}
    action=$1

    set_address() {
        ip address replace $ip/$mask dev $interface
        (in_outputs ${name}
         for i in lease mask ip router siaddr dns serverid subnet opt53 interface ; do
            echo ''${!i} > $i
         done)
    }
    case $action in
      deconfig)
        ip address flush $interface
        ip link set up dev $interface
        ;;
      bound)
        # this doesn't actually replace, it adds a new address.
        set_address
        ;;
      renew)
        set_address
        ;;
      nak)
        echo "received NAK on $interface"
        ;;
    esac
  '';
in longrun {
  inherit name;
  run = "${busybox}/bin/udhcpc -f -i ${interface.device} -s ${script}";
  dependencies = [ interface ];
}

# lease=86400
# mask=24
# ip=10.0.2.15
# router=10.0.2.2
# siaddr=10.0.2.2
# dns=10.0.2.3
# serverid=10.0.2.2
# subnet=255.255.255.0
# SHLVL=2
# opt53=05
# interface=eth0
# PATH=/nix/store/npy692wik809z3vdwrkrj2wixjkr33kp-busybox-mips-unknown-linux-musl-1.35.0/bin:/nix/store/
# pj0b27l5728cypa5mmagz0q8ibzpik0h-execline-mips-unknown-linux-musl-2.9.0.1-bin/bin:/nix/store/rfjiw4dnv29daqc9971qmica1h86l0s0-s6-linux-init-mips-unknown-linux-musl-1.0.8.0-bin/bin:/nix/store/4wn3jm7yy2gfi0is0yy75lifbq5zjwz7-s6-rc-mips-unknown-linux-musl-0.5.3.2-bin/bin:/usr/bin:/bin
# _=/nix/store/npy692wik809z3vdwrkrj2wixjkr33kp-busybox-mips-unknown-linux-musl-1.35.0/bin/env
# /