#!/usr/bin/env bash

# This script will update given netcup domain dns record with the actual ip of the calling service
# Parameters:
# IPVERSION: 4 or 6
# DOMAIN_NAME: the zone name eg. test.com
# DNS_RECORD_ID: the id of the dns record that should be updated
# HOSTNAMERECORD: the hostname in domain
# NC_Apikey: Api Key from your netcup account
# NC_Apipw: Api password from your netcup account
# NC_CID: Customer ID from your netcup account

IPVERSION=$1
DOMAIN_NAME=$2
DNS_RECORD_ID=$3
HOSTNAMERECORD=$4
NC_Apikey=$5
NC_Apipw=$6
NC_CID=$7
NC_ENDPOINT='https://ccp.netcup.net/run/webservice/servers/endpoint.php?JSON'
CACHE_PATH="/var/cache/update_netcup_ddns"

usage() {
  #
  # Displays usage of script
  #
  #   returns usage
  #

  echo
  echo "./update_netcup_ddns.sh <IPVERSION> <DOMAIN_NAME> <DNS_RECORD_ID> <HOSTNAMERECORD> <NC_Apikey> <NC_Apipw> <NC_CID>"
  echo
}

query_ip_address() {
  #
  # Queries the IP address in use
  #
  #   returns IP address or exits with log message
  #

  local IPVERSION=$1
  local CACHE_PATH=$2

  case $IPVERSION in
    4)
      QUERY_ADDRESS=$(curl -s -4 -q v4.ident.me | grep -oE '((1?[0-9][0-9]?|2[0-4][0-9]|25[0-5])\.){3}(1?[0-9][0-9]?|2[0-4][0-9]|25[0-5])')
      STATEFILE="$CACHE_PATH/ddns_state_ipv"$IPVERSION"_$DOMAIN_NAME.txt"
      ;;
    6)
      QUERY_ADDRESS=$(curl -s -6 -q v6.ident.me | grep -oE '^([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$')
      STATEFILE="$CACHE_PATH/ddns_state_ipv"$IPVERSION"_$DOMAIN_NAME.txt"
      ;;
    *)
      usage
      exit 1
      ;;
  esac

  if [ ! -d $CACHE_PATH ]; then mkdir -p $CACHE_PATH; fi
  if [ ! -f $STATEFILE ]; then touch $STATEFILE; fi

  if [ ! -z $QUERY_ADDRESS ]; then
    echo $QUERY_ADDRESS
  else
    logger -t $(basename $0) -p user.err "Unable to query IP address"
    exit 255;
  fi
}

get_auth_token() {
  #
  # Get auth token
  #
  #   returns auth_token
  #

  echo $(curl -s -X POST \
      $NC_ENDPOINT \
      --header 'Accept: */*' \
      --header 'Content-Type: application/json' \
      --data-raw '{
      "action":"login",
      "param":{
          "apikey": "'$NC_Apikey'",
          "apipassword": "'$NC_Apipw'",
          "customernumber": "'$NC_CID'"
      }
  }')
}

determine_record_type() {
  #
  # Determine dns record type
  #
  #   returns dns record type (currently support A and AAAA)
  #

  local IPVERSION=$1

  if [ $IPVERSION -eq 4 ]; then
    RECORDTYPE="A"
  elif [ $IPVERSION -eq 6 ]; then
    RECORDTYPE="AAAA"
  else
    logger -t $(basename $0) -p user.err "Could not determine IP version. Exiting"
    exit 1
  fi

  echo $RECORDTYPE
}

get_ip_from_state() {
  #
  # Get IP address currently set in DNS
  #
  #   returns address set in DNS
  #

#  local IPVERSION=$1
#  local CACHE_PATH=$2
#
#  STATEFILE="$CACHE_PATH/ddns_state_ipv"$IPVERSION"_$DOMAIN_NAME.txt"
#  LAST_ADDRESS=$(<$STATEFILE)
#
#  echo $LAST_ADDRESS

  sid=$(get_auth_token | tr '{}' '\n' | grep apisessionid | cut -d '"' -f 4)
  curl -s -X POST \
      $NC_ENDPOINT \
      --header 'Accept: */*' \
      --header 'Content-Type: application/json' \
      --data-raw '{
      "action":"infoDnsRecords",
      "param":{
          "apikey": "'$NC_Apikey'",
          "apisessionid": "'$sid'",
          "customernumber": "'$NC_CID'",
          "clientrequestid": "",
          "domainname": "'$DOMAIN_NAME'"
      }
  }' | jq -r '.responsedata.dnsrecords[] | select(.id == "'$DNS_RECORD_ID'") | .destination'
}

update_dns_record() {
  #
  # Update DNS record
  #
  #   returns the IP address updated in DNS
  #

  update=$(curl -s -X POST \
      $NC_ENDPOINT \
      --header 'Accept: */*' \
      --header 'Content-Type: application/json' \
      --data-raw '{
      "action":"updateDnsRecords",
      "param":{
          "apikey": "'$NC_Apikey'",
          "apisessionid": "'$sessionid'",
          "customernumber": "'$NC_CID'",
          "clientrequestid": "",
          "domainname": "'$DOMAIN_NAME'",
          "dnsrecordset": {
          "dnsrecords": [
              {
                "id": "'$DNS_RECORD_ID'",
                "hostname": "'$HOSTNAMERECORD'",
                "type": "'$(determine_record_type $IPVERSION)'",
                "destination": "'$QUERIED_ADDRESS'"
              }
            ]
        }
      }
  }')

  echo $update | jq -r '.responsedata.dnsrecords[] | select(.id == "'$DNS_RECORD_ID'") | .destination'
}

QUERIED_ADDRESS=$(query_ip_address $IPVERSION "$CACHE_PATH")
LAST_ADDRESS=$(get_ip_from_state)

# If IP address hasn't changed, exit, otherwise save the new IP
if [ "$QUERIED_ADDRESS" == "$LAST_ADDRESS" ]; then
  logger -t $(basename $0) -p user.notice "No update necessary for $HOSTNAMERECORD.$DOMAIN_NAME ($(determine_record_type $IPVERSION))!"
  exit 0
fi

echo $QUERIED_ADDRESS > "$CACHE_PATH/ddns_state_ipv"$IPVERSION"_$DOMAIN_NAME.txt"

sessionid=$(get_auth_token | tr '{}' '\n' | grep apisessionid | cut -d '"' -f 4)
if [ "$sessionid" = "" ]; then
    logger -t $(basename $0) -p user.err "SessionID was empty. Login failed."
    exit 1
fi
logger -t $(basename $0) -p user.notice "Successfully logged in"
logger -t $(basename $0) -p user.notice "Try registering new IP for FQDN $HOSTNAMERECORD.$DOMAIN_NAME ($QUERIED_ADDRESS - $(determine_record_type $IPVERSION))"

update=$(update_dns_record)

if [ "$update" == "$QUERIED_ADDRESS" ]; then
  logger -t $(basename $0) -p user.notice "Finished updating domain $DOMAIN_NAME"
else
  logger -t $(basename $0) -p user.err "Could not update $HOSTNAMERECORD.$DOMAIN_NAME ($QUERIED_ADDRESS - $(determine_record_type $IPVERSION))"
fi