#!/usr/bin/env bash
set -ex

EASY_RSA_LOC="/etc/openvpn/easyrsa"
SERVER_CERT="${EASY_RSA_LOC}/pki/issued/server.crt"

OVPN_SRV_NET=${OVPN_SERVER_NET:-172.16.100.0}
OVPN_SRV_MASK=${OVPN_SERVER_MASK:-255.255.255.0}

OVPN_PASSWD_AUTH=${OVPN_PASSWD_AUTH:-false}
OVPN_2FA=false
GOOGLE_2FA_AUTH_DIR="/etc/google-auth"

if [ ${OVPN_2FA} = "true" ]; then
  TARGETARCH=$(dpkg --print-architecture) 
  
  mkdir -p $EASY_RSA_LOC  
  sudo apt update -y
  
  sudo apt install -y openvpn iptables
  
  if [ ! -f "/usr/local/bin/easyrsa" ]; then
    sudo apt install easy-rsa
    sudo ln -sf /usr/share/easy-rsa/easyrsa /usr/local/bin/easyrsa
  fi
  
  if [ ! -f "/usr/local/bin/openvpn-user" ]; then
    cd /tmp
    wget "https://github.com/pashcovich/openvpn-user/releases/download/v1.0.4/openvpn-user-linux-${TARGETARCH}.tar.gz" -O - | sudo tar xz -C /usr/local/bin
  fi
  
  if [ -f "/usr/local/bin/openvpn-user-${TARGETARCH}" ]; then
    sudo ln -sf /usr/local/bin/openvpn-user-${TARGETARCH} /usr/local/bin/openvpn-user
  fi
fi

cd $EASY_RSA_LOC

if [ -e "$SERVER_CERT" ]; then
  echo "Found existing certs - reusing"
else
  if [ ${OVPN_ROLE:-"master"} = "slave" ]; then
    echo "Waiting for initial sync data from master"
    while [ $(wget -q localhost/api/sync/last/try -O - | wc -m) -lt 1 ]
    do
      sleep 5
    done
  else
    echo "Generating new certs"
    easyrsa init-pki
    cp -R /usr/share/easy-rsa/* $EASY_RSA_LOC/pki
    echo "ca" | easyrsa build-ca nopass
    easyrsa build-server-full server nopass
    easyrsa gen-dh
    openvpn --genkey --secret ./pki/ta.key
  fi
fi
easyrsa gen-crl

iptables -t nat -D POSTROUTING -s ${OVPN_SRV_NET}/${OVPN_SRV_MASK} ! -d ${OVPN_SRV_NET}/${OVPN_SRV_MASK} -j MASQUERADE || true
iptables -t nat -A POSTROUTING -s ${OVPN_SRV_NET}/${OVPN_SRV_MASK} ! -d ${OVPN_SRV_NET}/${OVPN_SRV_MASK} -j MASQUERADE

mkdir -p /dev/net
if [ ! -c /dev/net/tun ]; then
    mknod /dev/net/tun c 10 200
fi

if [ ${OVPN_2FA} = "true" ]; then
  cp -f /home/ubuntu/ovpn-admin/setup/openvpn.conf /etc/openvpn/openvpn.conf
else
  cp -f /etc/openvpn/setup/openvpn.conf /etc/openvpn/openvpn.conf
fi

if [ ${OVPN_PASSWD_AUTH} = "true" ]; then
  mkdir -p /etc/openvpn/scripts/
  cp -f /etc/openvpn/setup/auth.sh /etc/openvpn/scripts/auth.sh
  chmod +x /etc/openvpn/scripts/auth.sh
  echo "auth-user-pass-verify /etc/openvpn/scripts/auth.sh via-file" | tee -a /etc/openvpn/openvpn.conf
  echo "script-security 2" | tee -a /etc/openvpn/openvpn.conf
  echo "verify-client-cert require" | tee -a /etc/openvpn/openvpn.conf
  openvpn-user db-init --db.path=$EASY_RSA_LOC/pki/users.db
fi

[ -d $EASY_RSA_LOC/pki ] && chmod 755 $EASY_RSA_LOC/pki
[ -f $EASY_RSA_LOC/pki/crl.pem ] && chmod 644 $EASY_RSA_LOC/pki/crl.pem

if [ ${OVPN_2FA} = "true" ]; then
  if [ ! -f "/usr/local/lib/security/pam_google_authenticator.so" ]; then
    apt update && apt install -y \
    build-essential \
    linux-headers-$(uname -r) \
    autoconf \
    automake \
    libtool \
    cmake \
    make \
    git \
    libpam0g-dev \
    libpam-google-authenticator \
    qrencode
  
    cd /tmp
    rm -rf google-authenticator-libpam
    git clone https://github.com/google/google-authenticator-libpam
    cd google-authenticator-libpam/
    ./bootstrap.sh
    ./configure
    make
    make install
    rm -rf google-authenticator-libpam
  fi
  
  if [ ! -f "/etc/pam.d/openvpn" ]; then
    bash -c 'cat > /etc/pam.d/openvpn <<EOF
    auth    requisite       /usr/local/lib/security/pam_google_authenticator.so secret=/etc/google-auth/\${USER}  user=root
    account    required     pam_permit.so'
  fi
  
  if [ ! -f "/etc/openvpn/google-auth.sh" ]; then
    sudo mkdir -p /etc/google-auth
    sudo chown -R root /etc/google-auth
  
    sudo bash -c 'cat > /etc/openvpn/google-auth.sh <<EOF
    #!/bin/bash
    
    CLIENT=\$1
    HOST=\$(hostname)
    R="\e[0;91m"
    G="\e[0;92m"
    W="\e[0;97m"
    B="\e[1m"
    C="\e[0m"
    
    google-authenticator -t -d -f -r 3 -R 30 -W -C -s "\${GOOGLE_2FA_AUTH_DIR}/\${CLIENT}" || { echo -e "\${R}\${B}error generating QR code\${C}"; exit 1; }
    secret=\$(head -n 1 "\${GOOGLE_2FA_AUTH_DIR}/\${CLIENT}")
    qrencode -t PNG -o "\${GOOGLE_2FA_AUTH_DIR}/\${CLIENT}.png" "otpauth://totp/\${CLIENT}@\${HOST}?secret=\${secret}&issuer=openvpn" || { echo -e "\${R}\${B}Error generating PNG\${C}"; exit 1; }'
    
    sudo chmod +x $GOOGLE_2FA_AUTH_DIR/google-auth.sh
  fi
fi

mkdir -p /etc/openvpn/ccd

openvpn --config /etc/openvpn/openvpn.conf --client-config-dir /etc/openvpn/ccd --port 1194 --proto tcp --management 127.0.0.1 8989 --dev tun0 --server ${OVPN_SRV_NET} ${OVPN_SRV_MASK}