#!/usr/bin/env bash

set -eu

DIR=$(cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd)
MACADDR_FILE="$DIR/tinc-macaddr"
if [ -e "$MACADDR_FILE" ]; then
  echo "Skip generating MAC: '$MACADDR_FILE' does already exists."
  exit 1
else
  # Locally Administered Address Ranges:
  #x2-xx-xx-xx-xx-xx
  #x6-xx-xx-xx-xx-xx
  #xA-xx-xx-xx-xx-xx
  #xE-xx-xx-xx-xx-xx
  # Replacing x with any hex value.
  printf '02:1F:%02X:%02X:%02X:%02X\n' \
    $[RANDOM%256] $[RANDOM%256] $[RANDOM%256] $[RANDOM%256] \
    > "$MACADDR_FILE"
fi
cat $MACADDR_FILE