#!/bin/bash
# $1 : OpenVPN Config File
# $2 : Astaro .apc to create
# $3 : username
# $4 : password

if [ $# -lt 2 ] || [ $# -gt 4 ]
then
  echo
  echo Usage:
  echo ${0} openvpn-config.ovpn  output.apc [username] [password]
  echo username and password are optional and may be entered by the user
  echo The config file needs to contain the ca, cert and key directives
  echo that point to the corresponding files.
  exit
fi
if [ $# -gt 2 ] && [ $# -lt 4 ] # username only
then
  user=${3}
  echo "Please enter your password: "
  read pass
elif [ $# -gt 3 ] # username and password
then
  user=${3}
  pass=${4}
else	# read username and password from commandline
  user=`echo $1 | cut -d '@' -f1`
  if [ ${user} = ${1} ]
  then
    echo "Enter username: "
    read user
  fi
  echo "Please enter your password: "
  read pass
fi

# Read the filenames from the config-file
ca=`grep "^ca " ${1} | cut -d ' ' -f2 |tr -d '\n'`
key=`grep "^key " ${1} | cut -d ' ' -f2 |tr -d '\n'`
cert=`grep "^cert " ${1} | cut -d ' ' -f2 |tr -d '\n'`
# Write .apc header
printf "\x04\x06\x041234\x04\x04\x04\x08\x03\x0c\x00\x00\x00\x0a" > $2
# Extract protocol (UDP/TCP) from config file
var=`grep "^proto " ${1} | cut -d ' ' -f2 |tr -d '\n'`
# Determine length of the protocol and convert it to hex
varlen=`echo ${var} | tr -d '\n' | wc -c`
varlen=`echo "obase=16; ${varlen}" | bc -q`
# Write length to output file
printf "\x${varlen}" >> ${2}
# Write protocol to output file
echo $var | tr -d '\n' >> ${2}
# Write fix information to output file
printf "\x08\x00\x00\x00" >> ${2}
echo protocol >>${2}

# And so on...
var=`grep "^auth " ${1} | cut -d ' ' -f2 |tr -d '\n'`
varlen=`echo ${var} | tr -d '\n' | wc -c`
varlen=`echo "obase=16; ${varlen}" | bc -q`
printf "\x${varlen}" >> ${2}
echo $var | tr -d '\n' >> ${2}
printf "\x18\x00\x00\x00" >> ${2}
echo authentication_algorithm | tr -d '\n' >> ${2}

# Determine length of certifcate file
varlen=`cat ${cert} | wc -c` # Length decimal
hex=`echo "obase=16; ${varlen}" | bc -q`   # Lengthe hexadecimal
num=`echo "obase=16; ${varlen}" | bc -q | tr -d '\n' | wc -c` # Length of the hex-number
odd=`expr ${num} % 2` # hex-number: even or odd?
# TODO: Add a check for bigger hex-number (more than 4 digits)
if [ ${odd} -eq 0 ]
then  # even: swap AABB > BBAA
  varlen1=`echo "obase=16; ${varlen}" | bc -q | cut -b 3,4`
  varlen2=`echo "obase=16; ${varlen}" | bc -q | cut -b 1,2`
else  # odd: swap AAB > AB 0A
  varlen1=`echo "obase=16; ${varlen}" | bc -q | cut -b 2,3`
  varlen2=`echo "obase=16; ${varlen}" | bc -q | cut -b 1`
fi

printf "\x1\x${varlen1}\x${varlen2}\x0\x0" >> ${2}
cat ${cert} >> ${2}
printf "\xb\x0\x0\x0" >> ${2}
echo "certificate" | tr -d '\n' >> ${2}


varlen=`cat ${ca} | wc -c`
hex=`echo "obase=16; ${varlen}" | bc -q`
num=`echo "obase=16; ${varlen}" | bc -q | tr -d '\n' | wc -c`
odd=`expr ${num} % 2`
if [ ${odd} -eq 0 ]
then
  varlen1=`echo "obase=16; ${varlen}" | bc -q | cut -b 3,4`
  varlen2=`echo "obase=16; ${varlen}" | bc -q | cut -b 1,2`
else
  varlen1=`echo "obase=16; ${varlen}" | bc -q | cut -b 2,3`
  varlen2=`echo "obase=16; ${varlen}" | bc -q | cut -b 1`
fi

printf "\x1\x${varlen1}\x${varlen2}\x0\x0" >> ${2}
cat ${ca} >> ${2}

printf "\x7\x0\x0\x0" >> ${2}
echo "ca_cert" | tr -d '\n' >> ${2}

varlen=`cat ${key} | wc -c`
hex=`echo "obase=16; ${varlen}" | bc -q`
num=`echo "obase=16; ${varlen}" | bc -q | tr -d '\n' | wc -c`
odd=`expr ${num} % 2`
if [ ${odd} -eq 0 ]
then
  varlen1=`echo "obase=16; ${varlen}" | bc -q | cut -b 3,4`
  varlen2=`echo "obase=16; ${varlen}" | bc -q | cut -b 1,2`
else
  varlen1=`echo "obase=16; ${varlen}" | bc -q | cut -b 2,3`
  varlen2=`echo "obase=16; ${varlen}" | bc -q | cut -b 1`
fi

printf "\x1\x${varlen1}\x${varlen2}\x0\x0" >> ${2}
cat ${key} >> ${2}

printf "\x3\x0\x0\x0" >> ${2}
echo "key" >> ${2}

varlen=`echo ${user} | tr -d '\n' | wc -c`
varlen=`echo "obase=16; ${varlen}" | bc -q`
printf "\x${varlen}" >>${2}
echo ${user} | tr -d '\n' >> ${2}

printf "\x08\x00\x00\x00" >> ${2}
echo username | tr -d '\n' >> ${2}


var=`grep "^comp-lzo" ${1}|tr -d '\n'`
if [ ${var} = "comp-lzo" ]
then
  printf "\x0a\x01\x31\x0b\x0\x0\x0" >> ${2}
else
  printf "\x0a\x01\x31\x0b\x0\x0\x0" >> ${2}
fi
echo compression >> ${2}

var=`grep "^cipher " ${1} | cut -d ' ' -f2 |tr -d '\n'`
varlen=`echo ${var} | tr -d '\n' | wc -c`
varlen=`echo "obase=16; ${varlen}" | bc -q`
printf "\x${varlen}" >> ${2}
echo $var | tr -d '\n' >>${2}
printf "\x14\x00\x00\x00" >> ${2}

echo encryption_algorithm >> ${2}

varlen=`echo ${pass} | tr -d '\n' | wc -c`
varlen=`echo "obase=16; ${varlen}" | bc -q`
printf "\x${varlen}" >> ${2}
echo ${pass} | tr -d '\n' >> ${2}
printf "\x08\x00\x00\x00" >> ${2}
echo password >> ${2}

var=`grep "^tls-remote " ${1} | cut -d '"' -f2 |tr -d '\n'`
temp=`echo ${var} | grep "^tls-remote "`
if [ "${temp}" = "${var}" ]
then
  var=`grep "^tls-remote " ${1} | cut -d ' ' -f2 |tr -d '\n'`
fi
varlen=`echo ${var} | tr -d '\n' | wc -c`
varlen=`echo "obase=16; ${varlen}" | bc -q`
printf "\x${varlen}" >> ${2}
echo $var | tr -d '\n' >> ${2}
printf "\x09\x00\x00\x00" >> ${2}
echo server_dn >> ${2}

var=`grep "^remote " ${1} | cut -d ' ' -f3 |tr -d '\n'`
varlen=`echo ${var} | tr -d '\n' | wc -c`
varlen=`echo "obase=16; ${varlen}" | bc -q`
printf "\x${varlen}" >> ${2}
echo $var | tr -d '\n' >>${2}
printf "\x0b\x00\x00\x00" >> ${2}
echo server_port >> ${2}

var=`grep "^remote " ${1} | cut -d ' ' -f2 |tr -d '\n'`
varlen=`echo ${var} | tr -d '\n' | wc -c`
varlen=`echo "obase=16; ${varlen}" | bc -q`
printf "\x${varlen}" >> ${2}
echo $var | tr -d '\n' >> ${2}
printf "\x0e\x00\x00\x00" >> ${2}
echo server_address| tr -d '\n' >> ${2}