vpnclient_ynh/conf/scripts/route-up.d/20-vpnclient-set-dns

#!/bin/bash

is_dns_set() {
  if [[ "$ynh_dns_method" != "custom" ]]; then
    return 0
  fi

  current_dns=$(grep -o -P '^\s*nameserver\s+\K[a-fA-F\d.:]+$' /etc/resolv.dnsmasq.conf | sort | uniq)
  wanted_dns=$(echo "${ynh_dns}" | sed 's/,/\n/g'  | sort | uniq)
  [[ -e /etc/dhcp/dhclient-exit-hooks.d/ynh-vpnclient ]] \
  && [[ "$current_dns" == "$wanted_dns" ]]
}

ynh_dns_method=$(yunohost app setting vpnclient dns_method)
ynh_dns=$(yunohost app setting vpnclient nameservers)

# Set host DNS resolvers
if ! is_dns_set; then
  resolvconf=/etc/resolv.dnsmasq.conf

  cp -fa "${resolvconf}" "${resolvconf}.ynh"
  if [[ "$ynh_dns_method" == "custom" ]]; then
    cat << EOF > /etc/dhcp/dhclient-exit-hooks.d/ynh-vpnclient
echo "${ynh_dns}" | sed 's/,/\n/g' | sort | uniq | sed 's/^/nameserver /g' > ${resolvconf}
EOF
    bash /etc/dhcp/dhclient-exit-hooks.d/ynh-vpnclient
  fi
fi

if is_dns_set; then
  echo "[ OK ] Host DNS correctly set"
else
  echo "[FAIL] No host DNS set" >&2
  exit 1
fi