#!/bin/bash

function error 
{
	echo $1 >&2
	killall pltap-ovs 2>/dev/null || true
	exit 1
}

function is_switch_running
{
	ovs-appctl version >/dev/null 2>&1
}

if [ -z "$1" ]; then
	error "Usage: ${0##*/} <IP/PREFIX>"
fi

# TODO: check paramether validity

IP=${1%/*}
PREFIX=${1#*/}

set -e

# ensure ovs-vswitchd is running
if ! is_switch_running; then
	echo "ovs-vswitchd not running" >&2
	exit 1
fi
	

# check whether the address is already assigned
set -e
TAPNAME=$(ip addr show to "$IP/32" | perl -ne '/^\s*\d+:\s*([\w-]+):/ && print $1')
if [ ! -z "$TAPNAME" ]; then
    if ovs-vsctl br-exists "$TAPNAME"; then
		echo $TAPNAME
		exit 0
    fi
    error "$IP already assigned to $TAPNAME"
fi

TAPNAME=$(pltap-ovs)
vsysc vif_up << EOF
	$TAPNAME
	$IP
	$PREFIX
EOF
while ! ip link show up | egrep -q "^[0-9]+: +$TAPNAME:"; do
	echo "Waiting for $TAPNAME to come UP..." >&2
	sleep 1
done
ovs-vsctl add-br $TAPNAME -- set bridge $TAPNAME datapath_type=planetlab
echo $TAPNAME