#!/bin/execlineb -P
# SPDX-License-Identifier: EUPL-1.2+
# SPDX-FileCopyrightText: 2020-2021 Alyssa Ross <hi@alyssa.is>

importas -Si INTERFACE

ifte

{
  # This interface is connected to another VM.

  # The other VM's IP is encoded in the NIC-specific portion of the
  # interface's MAC address.
  backtick -E CLIENT_IP {
    awk -F: "{printf \"100.64.%d.%d\\n\", \"0x\" $5, \"0x\" $6}"
    /sys/class/net/${INTERFACE}/address
  }

  if { ip address add 169.254.0.1/32 dev $INTERFACE }
  if { ip link set $INTERFACE up }
  ip route add $CLIENT_IP dev $INTERFACE
}

{
  if { test $INTERFACE != lo }
  # This is a physical connection to a network device.
  background { s6-rc -bu change connman }
  if { s6-rc -bu change nftables }
  if {
    forx -pE module { nft_counter nft_masq }
    modprobe $module
  }
  nft add rule ip nat postrouting oifname $INTERFACE counter masquerade
}

grep -iq ^02:01: /sys/class/net/${INTERFACE}/address