#!/bin/bash

export PATH="$PATH:/sbin:/usr/sbin"

usage () {
    echo -e "Usage:\t$0 -a -b <BRIDGE NAME> [ -u <OWNER> ]"
    echo -e "\t\t-d -b <BRIDGE NAME> -t <TAP NAME>"
    exit 1
}

tap2brigde () {
    local bridge_id=$1
    local user_name=$2
    tap_id=$( tunctl -u "$user_name" -b )
    ip link set $tap_id up
    sleep 0.5
    brctl addif $bridge_id $tap_id
    echo $tap_id
}

removetap () {
    local bridge_id=$1
    local tap_id=$2
    brctl delif $bridge_id $tap_id
    sleep 0.5
    tunctl -d $tap_id
}

[ $# -eq 0 ] && usage

# parse options
while getopts ":adb:t:u:" opt; do
  case $opt in
    a)
      addtap=1
      ;;
    d) 
      deltap=1
      ;;
    b)
      bridge_id="$OPTARG"
      ;;
    t)
      tap_id="$OPTARG"
      ;;
    u)
      owner="$OPTARG"
      ;;
    \?)
      usage
      ;;
    :)
      echo "Option -$OPTARG requires an argument." >&2
      usage
      ;;
  esac
done

[ -z "$owner" ] && owner="root"

if [ -n "$addtap" ]; then
    tap2brigde "$bridge_id" "$owner"
elif [ -n "$deltap" ]; then
    removetap "$bridge_id" "$tap_id"
fi